What is dangerous laryngotracheitis in chickens: symptoms and methods of dealing with the disease. Laboratory methods must also be used.

Laryngotracheitis is becoming an increasingly common infectious disease in chickens every year. Today the problem is relevant for England, Sweden, France, Yugoslavia, Holland, Italy, Canada, Indonesia, Hungary, Australia, Romania, USA, Poland, Spain, Germany, New Zealand, Russia.

Outbreaks are recorded in almost every region of these countries. Especially large poultry farms suffer from the infection, but small farms cannot avoid cases of laryngotracheitis. A breeder of any size must have an understanding of the pathology and how to cure it.

Infectious laryngotracheitis refers to respiratory diseases. The causative agent is the Herpesviridae virus. Most often, chickens are infected, but other poultry (pheasants, peacocks, decorative quails) are also susceptible to infection. Also, laryngotracheitis is common among pigeons.

Infectious laryngotracheitis is a respiratory disease.

The first name of the disease is tracheolaryngitis. In 1925 it was opened by Titsler and May in the USA. In 1931, parts of the name were reversed, as they have remained to this day. Infection has long been compared with bronchitis, but was transferred to the status of an independent problem.

The pathogen virus is survivable in any climate, resistant to many drugs. It can be quite difficult to defeat him, especially when it comes to complex forms of manifestation. Laryngotracheitis is expressed in violation of the respiratory function. Infection is localized in the trachea and larynx, spreading to the conjunctiva, which causes lacrimation.

Outbreaks of mass infection are characterized by seasonal binding. More often they occur in spring and autumn at high humidity and low air temperatures. In winter, the virus actively settles in birds with low immunity.

The metabolism of harmful cells is slow, so symptoms may not appear immediately, but up to 2 years from the moment of infection. Since poultry live in a collective environment, the spread of the disease is rapid. Up to 80% of the flock can be affected per day.

Recovered individuals acquire their own immunity, but spread the accumulated virus for a long time.

As a rule, the transfer is carried out by airborne droplets with particles of cough sputum. Even a person can become a carrier if chicken exudate gets on clothes or equipment. The disease is transmitted to people in conditions of prolonged contact with infected livestock, but infection through meat, feathers and eggs is excluded.

Laryngotracheitis has no age binding, however, it is more difficult for young animals up to 100 days of life to endure it. In the northern regions, chicks up to 20 days of age often get sick. Recovered individuals acquire their own immunity, but they spread the accumulated virus for a long time, so they cannot be introduced into an unvaccinated herd. Eggs from laying hens with laryngotracheitis are not incubated.

Diseases are indirectly promoted by poor ventilation, too high humidity, drafts of unsanitary conditions in the chicken coop, unbalanced nutrition and beriberi. Mortality from infection reaches 15%.

The appearance of laryngotracheitis on a farm is always associated with impressive economic damage. Livestock often fall ill completely or in a larger percentage. Many individuals die (especially young animals), which immediately deprives the breeder of a significant part of the future meat production.

Due to outbreaks of laryngotracheitis, most of the livestock die, which incurs heavy losses.

In addition, the owner of the flock has to spend money on medicines, veterinarians, transportation of a specialist or birds to an appointment. Sometimes inventory needs to be replaced. Not a small amount is spent on prevention - disinfectants, vaccines.

The laryngotracheitis virus spreads primarily through the mucous membranes of the nasopharynx, mouth and conjunctiva. The incubation period is from 1 to 3 days, but it happens that the symptoms of infection appear by the end of the first day.

It happens that the disease, colibacillosis, hemophilia, bronchitis or other bacteriological infections. To confirm the diagnosis, an analysis for the isolation of viruses from the pathological material is necessary.

Important. Experts say that with a careful approach, laryngotracheitis can be suspected in 10-15 minutes, and cured in no more than a week.

Profuse lacrimation from the eyes, runny nose, ajar beak should instantly arouse suspicion in the owner. Often, due to the swollen larynx, the bird experiences pain and refuses to eat. Among the common symptoms, a blue scallop and earrings, a noticeable weakness of the bird, are also noted. The remaining signs depend on the form of leakage.

With laryngotracheitis, chickens have watery eyes, they breathe heavily, refuse to eat.

Symptoms of the hyperacute form

With this form, the symptoms appear massively and suddenly.

Signs are brightly expressed, with a rapid increase in intensity:

Heavy breathing with wheezing and wheezing, reaching suffocation (increases at night).
The bird stretches its neck and shakes its head in the hope of inhaling more freely.
Paroxysmal severe cough, often with bloody sputum.
The chicken lies with its eyes closed a lot.
Mucus is observed on the floor and walls in the poultry house.

The super-sharp form is considered the deadliest. It can kill up to 50% of the livestock. It is the most difficult to treat, because very quick measures are required.

The acute form of laryngotracheitis does not manifest itself as sharply as hyperacute. Chickens show symptoms in several heads at intervals.

Passive attitude to feeding and general activity.
On examination, white cheesy or slimy masses in the beak, redness, swelling of the mouth and larynx.
Hearing whistles during inhalation and exhalation.

At acute form chickens do not eat well, become lethargic.

An acute course is dangerous for death due to blockage of the lumen of the larynx with accumulations of secretions. If an individual has an asthma attack, she needs urgent help in expectorating and removing edema. This form without therapy or with its insufficiency often develops into a chronic one. Mortality with proper treatment does not exceed 10%.

Most of the time there are no symptoms.

They appear periodically and increase before the death of the chicken:

Decline in weight gain and egg production.
Repeated attacks of spasmodic cough until suffocation (even at long intervals).
Conjunctivitis, sometimes photophobia.
Frequent discharge of mucus from the nostrils.

With a drop in egg production, the quality of the egg is preserved. Morbidity and mortality in the chronic form are in the region of 1-2%.

In chronic laryngotracheitis, symptoms occur only occasionally.

Symptoms of the conjunctival form

It usually occurs in chicks 10-40 days old, but can also affect adult chickens:

Inflamed, reddened whites of the eyes, photophobia.
Finding the third century on the eyeball, sticking of the eyelids.
Mucous and frothy discharge from the eyes.
Loss of orientation due to vision problems.
Corneal efflorescence.
The trachea may be clogged with blood clots, the mucous membrane of the throat is cherry.

The conjunctival form is often curable in 1-3 months. The main danger is the complete loss of vision due to atrophy of the tissues of the eye.

The atypical form of laryngotracheitis proceeds imperceptibly. As a rule, the individual carries and spreads the virus, but does not have obvious symptoms and the danger of death. This happens with strong immunity or when the bird is already cured.

The main symptoms can be seen only when examining the larynx - swelling, redness, small sores are possible due to the destroyed epithelium.

The atypical form of laryngotracheitis proceeds imperceptibly.

Therapy of laryngotracheitis is considered by many to be unjustified. From an economic point of view, it is considered more profitable to purchase a new livestock than to treat a sick flock of chickens. While keeping old individuals, the virus will still remain on the farm, it will spread to young animals, which will need to be vaccinated regularly.

Treatment of the disease is offered according to a non-specific scheme:

Ensuring high-quality heating, ventilation in the poultry house, increasing the content of vitamins in the feed.
Drinking broad-spectrum antibiotics (tetracycline, norfloxacin, ciprofloxacin). Furazolidone powder is mixed into food (8 g of medicine per 10 kg of feed).
Iodtriethylene glycol, gentamicin, lactic acid are aerosolized in the poultry house in the presence of livestock.
If it is possible to isolate chickens, they are disinfected with a 15-minute run-off of a mixture of turpentine (2 mg) and bleach (20 mg) per 1 cubic meter of space.
Give individuals vitamin mixtures such as RexVital, Aminivital, Chiktonik, ASD-2 up to 1 ml per 100 chickens.

With laryngotracheitis, chickens are soldered with antibiotics, such as tetracycline.

Important. When slaughtering the old livestock, the premises must be disinfected along with the inventory before the new one is settled.

Disease prevention

Prevention is carried out in three areas:

Compliance with sanitation in the poultry house, keeping density, regular inspections, full feeding. Separation of livestock by age, quarantine of individuals before relocation. Periodic disinfection of the chicken coop with Virocon or Glutex during the flock.
The use of vaccines for the formation of immunity to the causative agent of laryngotracheitis. Cloacal, intraocular, oral, aerosol administration. In prosperous areas, vaccination is not recommended so as not to artificially cause outbreaks.
If an infection is detected more than 2 times, the export of chickens from the farm is prohibited by law.

There are two types of vaccines to prevent laryngotracheitis. The first are produced on the basis of chicken embryos. They give strong protection against a specific virus, but can cause serious complications in the body as a whole. In the second, cell culture is the raw material. Such varieties do not cause adverse reactions, but protection from them cannot be called serious.

Some farmers vaccinate their birds with drugs for laryngotracheitis.

The most sought-after vaccines against infectious laryngotracheitis in the veterinary environment are those sold in packages of more than 1000 doses.

These include:

Avivak, Russia;
Intervet, The Netherlands;
AviPro, Germany;
Vaccine from VNIIBP strain, Russia;
Nobilis ILT.

Infectious laryngotracheitis (ILP) is an acute infectious respiratory disease of chicken birds characterized by catarrhal-hemorrhagic inflammation of the mucous membranes of the trachea, nasal cavity, conjunctiva and accompanied by shortness of breath, wheezing and coughing.

History reference. The disease was first described in 1925. in the US by May and Titsler called tracheolaryngitis. For a long time infectious laryngoracheitis of birds was not differentiated from infectious bronchitis.

Later, Bigs, Silk and Hawn proved the independence of these two diseases, and from 1931 the disease began to be called "infectious laryngotracheitis".

In the USSR, this disease was established in 1932. R.T. Batakov. In 1951

S.T. Shchennikov prepared a vaccine on chicken embryos.
Infectious laryngotracheitis of birds is common in the USA, Canada, South America, Europe, Africa, Australia, and Asia. In Russia, ILP is registered mainly in farms with industrial production of poultry.

Economic damage with ILP, it consists of the waste of birds, mortality reaches 15-50%, a decrease in egg production in ill and recovered laying hens by 10-30%, weight gain. The cost of measures to stop the infection. The premature culling of a sick bird causes great damage.

Etiology. The causative agent of ILP is a virus that belongs to the Herpesviridae family. The virus is found in large quantities in the exudate and epithelial tissues of the upper respiratory tract, in a smaller amount it can be found in the liver and spleen. The data on the size of the virus are contradictory: some researchers consider them from 30 to 100nµ, others from 150 to 240nµ. Virions are spherical in shape. Virions have three structural components: a core (nucleoid), a capsid with capsomeres, and an envelope. The particle size depends on the location of the virus, for example, in the cytoplasm it is larger than in the nucleus of the affected cell.
Viruses pass through Berkefeld W and N filters, Seitz E.K. and membrane ultrafilters with pores from 0.7 to 0.9nµ. Pathogen I.L.P. is constantly found in tracheal mucus, exudate of the larynx, conjunctiva, less often in the blood, spleen and liver of sick chickens. The serum of recovered ILP contains specific virus-neutralizing antibodies. Researchers distinguish between virulent and weakly virulent viral strains that lack antigenic differences.
The virus is stable in the external environment, especially at sub-zero temperatures. In frozen carcasses, the virus persists for more than 19 months, in corpses buried in the ground in summer to a depth of 120 cm - up to 47 days, in corpses on the surface of the earth (April-May) - over 30 days, dried - 359 days. At a temperature of 37 ° C on the shell of eggs, it dies after 12 hours, when heated to 55 ° C - after 2 hours, when boiled - immediately. In the poultry house, the virus persists for no more than 6-9 days. Sunlight kills the virus after 7 hours. The virus is not resistant to the action of disinfectants, 3% sodium hydroxide solution and 3% cresol solution inactivate it after 30 seconds.

epidemiological data. Under natural conditions, to the I.L.K. chickens, pheasants, peacocks and turkeys are susceptible. Young chickens aged 5 months to a year are more susceptible, but chickens from 20-35 days of age can get sick.

I.L.K. some seasonality is characteristic, which is associated with changes in weather conditions, low temperature, high humidity in the premises and the deterioration of bird keeping in winter in household plots and peasant farms. Additionally, low temperatures contribute to a longer preservation of the pathogen in the external environment.

The disease in young hens and chickens occurs after the transfer of birds to other premises with worse conditions (high humidity, insufficient ventilation, inadequate feeding, etc.).
Chicks hatched from full-fledged hatching eggs are resistant to I.L.C. in the first days of life.

In dysfunctional large poultry farms with a flow system of poultry rearing, the disease often becomes stationary. The stationarity of the disease in the farm is explained by the long-term virus carrier in a sick bird (up to two years). Virus carrying in birds vaccinated with live vaccines lasts at least 90 days.

The nature of the course of ILC is directly affected by the conditions of keeping and feeding the birds by the time the infection enters the poultry house: dampness in the room, poor ventilation, overcrowding, unbalanced feeding rations.

Epizootic strains of viruses differ in virulent properties, the degree of which can vary significantly.

The main source of infection in the farm is a sick bird and virus carriers. Transmission factors are food, water, objects, shoes and clothes contaminated with secretions of a sick bird, etc. Infection occurs through the air. A sick bird, when coughing, throws into the air small droplets of exudate containing the virus. Wild bird, rats can be mechanical carriers of the disease.

If in an infected I.L.K. the flock does not introduce susceptible birds. Then, under good conditions of feeding and keeping, the spread of the disease can stop in 2-4 weeks.

Pathogenesis. After entering the damaged mucous membranes of the larynx, trachea, cloaca, the virus penetrates the epithelial cells with the formation of intranuclear inclusions and causes an acute inflammatory process. The virus, having a tropism for the epithelial tissues of the respiratory tract, begins to actively multiply in them, causing edema and lymphocytic infiltration. In the initial stage of the disease in the lumen of the trachea, we find a mucous exudate, later, as a result of hemorrhages, blood and fibrin are mixed with the exudate. From the epithelial tissues, the virus spreads through the bloodstream to all organs of the bird. However, pathological changes in them usually do not occur. With laryngotracheitis, the viremia is short, the virus remains in the epithelial tissues of the trachea and larynx for a long time.

The formation of caseous plugs in the lumen of the trachea indicates the accession to the main process of opportunistic microflora. In such cases, isolation of the virus can be difficult. Cellular detritus, fibrin and blood cells form a clot that clogs the lumen of the trachea and causes clinical symptoms of suffocation and death of the bird.

Symptoms and course of the disease. The incubation period, depending on the virulence and amount of the virus that has entered the body, as well as on the resistance of the bird to the disease, ranges from 2 to 30 days. The first clinical symptoms of the disease in birds when the virus enters the intratracheal route appear after 3-7 days.
The course of the disease with I.L.P. may be acute, subacute, chronic and asymptomatic. At the same time, three forms of the disease are distinguished in a sick bird: laryngo-tracheal, conjunctival and atypical.

In case of acute of the laryngo-tracheal form, as a rule, individual chickens fall ill at first, and after 7-10 days, the whole bird of the disadvantaged group. In a sick bird, we note general oppression, lethargy; appetite disappears, they refuse to feed, the bird becomes inactive, sits with its eyes closed. When carefully listening to a calmly sitting bird in the evening, we hear a variety of whistling, croaking and wheezing sounds. Blockage of the larynx, trachea with exudate leads to respiratory failure. The bird breathes through an open beak, the act of inhalation and exhalation is difficult. When carrying out palpation in the larynx and tracheal tube, it causes coughing fits in the bird. The bird coughs up exudate, which sometimes contains an admixture of blood. When examining the open beak, hyperemia and swelling of the mucous membrane of the larynx and trachea are noticeable, sometimes with hemorrhages. In protracted cases, cheesy-fibrinous deposits accumulate around the larynx. In a sick bird, egg production stops. Mortality in acute laryngotracheitis is often 10-60%, depending on the adverse factors of feeding and maintenance.

Subacute course I.L.P. lasts 2-3 weeks, clinical signs are less pronounced. The bird recovers or the disease becomes chronic (over a month) and is characterized by periodic improvement in the condition of the bird. The bird has a cough, shortness of breath, anemic crest and wattles, when examining the pharynx and larynx, fibrinous, easily removable grayish overlays are found, oviposition is reduced.

conjunctival form a disease that usually proceeds chronically more often affects chickens with an intensive in-line rearing system, when over-infection of birds of different ages occurs. At the beginning, individual chickens of 10-15 days of age fall ill, and later the entire batch of poultry is affected. The main clinical signs are hyperemia of the mucous membranes of the eye, deformation of the palpebral fissure (narrowing of the palpebral fissure, protrusion of the 3rd century in the inner corner of the eye and sinusitis), eyelid edema, photophobia, lacrimation. During this period of the disease, the body temperature of chickens is increased by 1-2 °. The secreted exudate glues the eyelids of the eyes, hemorrhages are noticeable on the mucous membrane of the conjunctiva, fibrinous masses accumulate under the third eyelid, keratitis and panophthalmia occur with loss of vision. The process involves the infraorbital sinus, the mucous membranes of the nasal cavity.

The conjunctival form of infectious laryngotracheitis lasts from 20 days to 2-3 months and leads to the exhaustion of chickens and their increased rejection. This form of the disease can affect 5-90% of chickens up to 60 days of age. The disease is most severe when poultry is kept in rooms with high humidity and high ammonia content.

Atypical form detected by serological studies of the blood serum of birds. Often infectious laryngotracheitis occurs in association with other infections, such as respiratory mycoplasmosis, colisepticemia.

Pathological changes. In the laryngo-tracheal form, changes are found in the larynx and trachea, the mucous membrane of which is highly hyperemic, edematous, with small hemorrhages. The lumen of the trachea contains a different amount of mucous, serous or bloody exudate. With a long course in the lumen of the larynx, we find a caseous plug, often clogging the entire lumen. On the mucous membrane of the oral cavity on one or both sides of the root of the tongue and on its frenulum, we sometimes find caseous-fibrinous small, easily removable plaques; less often - caseous foci in the lungs. Sometimes we find catarrhal-hemorrhagic inflammation of the cloaca, less often individual sections of the small intestines. In the Fabrician bag, a compacted curd-purulent mass is often observed. In the conjunctival form, the mucous membrane of the eyelids of one or both eyes is hyperemic, edematous, in some the cornea and eyeball are affected. In the early stages of I.L.P. histological examination of epithelial cells of the affected tracheal mucosa reveals characteristic intranuclear inclusions (acidophilic bodies), cell infiltration and desquamation of cells of the tracheal mucosa.

Diagnosis. We put it on the basis of epizootological, clinical, pathoanatomical data, as well as the results of laboratory studies (detection of intranuclear inclusions in the tracheal epithelium, the virus in the same place using fluorescent antibodies, RDP, RN). In the atypical course of the disease, laboratory tests are carried out. After exclusion of bacterial infections, a bioassay is placed, a virus is isolated, a neutralization reaction is performed on embryos, a double diffusion precipitation reaction in agar gel, histosections are examined for the presence of intranuclear inclusions of a rounded or sausage-shaped shape, surrounded by clearly visible rims.

If a disease of birds with ILP is suspected, a clinically ill bird in the initial stage of the disease in the amount of 4-5 heads and fresh corpses are sent to the veterinary laboratory for examination.

Differential Diagnosis. I.L.P. must be distinguished from, and, contagious rhinitis,.
Pseudoplague of birds is characterized by an epizootic course, a characteristic lesion (ring of hemorrhages) of the mucous membrane of the glandular stomach, and ulcers on the intestinal mucosa.

Respiratory mycoplasmosis spreads slowly, affects the air sacs, and deaths are rare.

To exclude smallpox, the bird is clinically examined for the presence of smallpox lesions. The diphtheroid and conjunctival forms of smallpox, due to the similarity of clinical symptoms, can be differentiated by isolation and typing of the virus.

A-avitaminosis is characterized by easily removable plaque in the oral cavity, the absence of asthma attacks.

Immunity and immunization. After recovering from I.L.K. chickens acquire long-term immunity to subsequent infection. The mechanism of its formation is determined by cellular and humoral factors. Antibodies after infection appear after 14-20 days and remain in the blood serum for 2-3 months. The duration of immunity is 5-7 months. For immunization, naturally weakened and attenuated strains are used. Currently, in Russia and the countries of the customs union, VNIIBBP and VNIIVViM vaccines are used. These vaccines are used by rubbing into the mucous membrane of the cloaca, instillation into the conjunctiva and aerosolized. When carrying out aerosol vaccination, immunity develops after 4-5 days and lasts up to a year. In poultry farms, the embryo-virus-vaccine from the clone NT of the TsNIIPP strain is widely used, which is currently less reactogenic.

Treatment. At the moment, there are no specific effective therapeutic agents for ILC. In order to reduce the loss of poultry and prevent the decline in egg production, antibiotics are used in combination with furozolidone and trivitamin, dioxidine (indoors), nigras (in the form of an aerosol).

Prevention and control measures. For the prevention of I.L.K. poultry owners must strictly implement measures to protect the economy from the introduction of pathogens of infectious diseases. Accomplishment of your farm with eggs intended for incubation and one-day-old chicks should be carried out only from farms that are safe in terms of ILC.
It is necessary to carry out veterinary and sanitary measures for the proper care, maintenance and feeding of the bird, especially in the case of cage-free keeping. Disinfect indoor air in the presence of birds using drugs that contribute to the partial inactivation of the virus and bacterial microflora in the upper respiratory tract. It is necessary to keep the bird separately depending on age. Unauthorized persons should not be allowed into the territory of the farms. When establishing the disease of birds with laryngotracheitis in accordance with the order of the Ministry of Agriculture of the Russian Federation No. 476 of December 19, 2011 "On approval of the list of contagious, including especially dangerous animal diseases for which restrictive measures (quarantine) can be established" by the decision of the Governor of the region on the economy (farm, poultry house) impose quarantine and impose restrictions on it. Activities in a dysfunctional farm are carried out in accordance with the temporary instruction on measures to prevent and eliminate the disease of birds with infectious laryngotracheitis. Approved by the Main Directorate of Veterinary Medicine of the USSR Gosagroprom on April 1, 1983. Under the terms of quarantine, it is prohibited:

movement of poultry within the holding (farms, branches, zones) during the outbreak of the disease;
import to a dysfunctional economy (farm, branch, zone) and export from it of birds of all ages;
export of hatching eggs to other farms;
use of eggs from dysfunctional poultry houses for incubation within the farm;
export of feed, equipment and inventory from disadvantaged industrial premises and from the territory of a disadvantaged economy (farms, departments, zones);
importation and storage of eggs received in a dysfunctional department, zone, to the egg storage of the farm;
the entrance to the territory of a dysfunctional economy and the exit of people from it without complete sanitization and change of clothes and shoes.

During the period of trouble of the economy it is allowed:

export of food eggs from a dysfunctional department (zone, farm) after disinfection to a trading network within the region;
incubation of eggs for on-farm purposes from birds of safe poultry houses after aerosol disinfection with a formaldehyde solution according to the scheme: the first time - no later than 1.5-2 hours after laying, the second - packed in containers in a special vehicle or the disinfection chamber of the hatchery, the third - after sorting before laying in the incubator , the fourth - 6 hours after the start of incubation;
delivery of hatching eggs and day-old chicks to a safe department, farm zone;
in the absence of a slaughterhouse on the farm, the export to poultry meat processing enterprises of birds of safe poultry houses subject to planned slaughter, with the permission of the state veterinary supervision of the region (krai, republic that does not have a regional division).

When ILP occurs for the first time on the farm, in order to prevent the spread of the disease, all birds in a dysfunctional poultry house are killed. At the same time, all necessary veterinary and sanitary measures are taken to ensure the destruction of the pathogen in the external environment.
When the disease spreads to other poultry houses, a thorough culling is carried out and sick and weak birds are slaughtered at the sanitary slaughterhouse of the economy (farms, departments, zones).

All clinically healthy birds are immunized with the ILP vaccine in accordance with the instructions for its use.

The farm is improving the feeding and keeping of birds, introducing anti-stress drugs (supplements) into the diet.

Each poultry house is assigned attendants, who are provided with overalls, special footwear, and disinfectants.
Poultry is slaughtered in compliance with veterinary and sanitary rules under the supervision of a veterinarian, followed by disinfection of slaughter sites, inventory and equipment.

If it is necessary to slaughter a large batch of poultry from a dysfunctional poultry house and it is impossible to slaughter it on the farm within 2 days with the permission of the regional veterinary department, etc. it is allowed to export clinically healthy poultry to meat processing enterprises in compliance with the relevant veterinary and sanitary rules.
Fluff and feathers obtained from the slaughter of birds from dysfunctional poultry houses are disinfected in accordance with clause 3.6. instructions.

Containers and boxes after transporting poultry for slaughter, meat containers, as well as containers, cardboard pads, boxes and other containers used for transporting eggs are subject to mandatory cleaning and disinfection.

During the period of trouble, the farms (departments) according to the ILC carry out a thorough mechanical cleaning, as well as the current and final disinfection of dysfunctional poultry houses, hatcheries, utility rooms, inventory and equipment, production areas, means of transport and other objects, as well as disinfestation and deratization in the manner and terms provided by the current Instructions for veterinary disinfection, disinfestation, disinfestation and deratization.

Litter and deep litter are taken to the litter storage facility for biothermal disinfection.

Restrictions on ILC in the farm (department, zone) are removed 2 months after the last case of slaughtering a sick and recovered bird and carrying out final veterinary and sanitary measures.

Sometimes poultry lovers do not have feathered pets for the reason that they are very afraid for their health and do not know how to treat a sick chicken. Indeed, in most cases, a sick bird is treated in the old fashioned way - with an ax. But we consider this an extreme measure, it is quite possible to diagnose the disease and cure the chicken. Our articles are designed to help you in the fight against chicken ailments, and today the turn has come to deal with such a scourge as laryngotracheitis in chickens - the symptoms and treatment will be described in detail in our article!

What is laryngotracheitis?

Laryngotracheitis is an acute infectious respiratory disease caused by a virus of the Herpesviridae family. Not only chickens are susceptible to this disease, but almost all poultry and pigeons. The virus infects the larynx, trachea and conjunctiva of the bird, causing difficulty in breathing and tearing. Laryngotracheitis is widespread everywhere, because poultry farms exist on all continents. A dangerous virus is stable and tenacious, which makes it difficult to fight it.

The original name of this disease is tracheolaryngitis, its authors May and Titsler. In 1925 in the USA they discovered and described this disease. Later, the name changed to infectious laryngotracheitis, this happened in 1931. At the same time, infectious laryngotracheitis was recognized as an independent disease, because before that it had been compared with infectious bronchitis for a long time.

Some seasonality is characteristic of infectious laryngotracheitis. Outbreaks of the disease can occur during the cold season. After all, the development and spread of the virus is facilitated by high humidity and low temperature.

At low temperatures, the virus in the external environment slows down its metabolic processes and persists longer. A chicken that has suffered laryngotracheitis and survived after it will be a virus carrier for 2 years, so it is forbidden for her to contact her relatives. The disease spreads very quickly, because chickens are creatures that live in a large close-knit team. It is quite possible to infect about 80% of your flock in a day if you are dealing with a hyperacute form of the disease, which will be discussed in more detail below. Infection occurs, as a rule, through droplets of exudate that a sick chicken throws out during a cough (airborne).

They contain a high concentration of a dangerous virus that quickly spreads throughout the chicken coop, without knowing it, you yourself can become a carrier of the disease. If the infected exudate gets on your clothes or equipment and then you go into a healthy chicken coop - unfortunately, most likely the virus will now settle there too. All age groups of birds, regardless of breed, are susceptible to laryngotracheitis. However, young individuals aged 60-100 days are most susceptible to the virus.

Symptoms

First of all, laryngotracheitis affects the mucous membranes of the bird, i.e., the mucous membranes of the nasal and oral cavities and the conjunctiva. The virus develops quickly and the first manifestations of the disease can be seen after 24 hours. First of all, the larynx swells in the bird and the eyes are watery; when pecking, the bird experiences pain. Therefore, she either refuses to eat at all, or eats with a noticeable slowdown. It is believed that an experienced poultry farmer is able to diagnose laryngotracheitis in 10 minutes and cure in 5-6 days.

Otherwise, he can say goodbye to 15% of his livestock - this is exactly the mortality from this disease in its acute course. And the health of the surviving livestock and all subsequent ones will be at risk. Laryngotracheitis can proceed in different ways, depending on the course of the disease, it is divided into acute form, hyperacute and chronic. Consider the symptoms of each form separately.

Super sharp shape	acute form	chronic course
It occurs, as a rule, suddenly, the infection of birds occurs rapidly, all the symptoms are obvious. With a hyperacute form, the bird begins to breathe heavily, it seems to be suffocating and stretches its head, trying to take a larger breath of air. Birds may have a violent cough with bloody expectoration. Trying to overcome attacks of suffocation, the bird shakes its head. The general condition of the bird is depressed, it refuses to eat and behaves passively, usually standing with its eyes closed. In a poultry house where sick birds are kept, mucous secretions can be seen on the floor or walls. Especially heavy breathing of birds is observed at night. With this form of laryngotracheitis, mortality is most likely, if no action is taken, then after two days the first cases of death can be observed. As a result, for 50% of the livestock, laryngotracheitis can become fatal.	The acute form begins and spreads not as sharply as the previous one. A bird affected by laryngotracheitis loses its appetite and sits with its eyes closed most of the time. The general condition of the bird can be described as lethargic and passive. Due to the swelling of the larynx, most of the time the bird breathes through its beak, and its breathing is difficult, with wheezing and whistling. If you look into the bird's mouth, you can see swelling and redness of the mucous membranes, and white spots on the larynx. If the chicken is not helped, due to the abundance of secretions, the trachea or larynx may become blocked and the bird will die from suffocation.	If the acute form of infectious laryngotracheitis is not treated, surviving hens may develop a chronic form of the disease. The disease can be almost asymptomatic, and only before the death of the bird, symptoms characteristic of laryngotracheitis may appear. The chronic form can manifest itself as conjunctivitis. A modification of the bird's eye is observed, photophobia may develop in young animals. Due to such negative deformations, birds can lose their sight.

When diagnosing infectious laryngotracheitis, the first thing they pay attention to is the breathing of the bird. If you notice that the feathers of the tail move when the chicken breathes, this is the first wake-up call. Any extraneous sounds that a bird makes when breathing should not go unnoticed. If, in combination with shortness of breath, inflammation and tearing of the eyes are also attached, then the chicken has almost 100% laryngotracheitis. When a slaughtered chicken is opened, with the naked eye, modifications of almost all organs are visible, to a greater extent, of course, the respiratory organs.

Treatment

The bad news is that a cure for laryngotracheitis has not yet been invented. Treatment is usually symptomatic with antibiotics. The drugs are not able to kill the virus completely, but can significantly reduce its activity, thereby helping the bird's immunity to fight the disease and facilitating the general condition of the chicken and the course of the disease. The main condition is to immediately begin treatment as soon as laryngotracheitis has been detected in chickens. Significant help in the fight against laryngotracheitis will be provided by biomycin and streptomycin in combination with trivit and furazolidone.

Special attention should be paid to the diet of the chicken that is receiving treatment. Vitamins A and E will help the bird to overcome laryngotracheitis due to the fact that they will dissolve fat cells and thus destroy the beneficial habitat of the virus. In order not to deal with an unpleasant disease - laryngotracheitis, preventive measures are very important. Vaccination of young animals is used as a preventive measure, especially if you keep a decent livestock or own your own mini-poultry farm. Moreover, vaccination can be not only standard, but also cloacal.

To do this, a virus is applied to the mucous membrane of the cloaca and gently rubbed. After a few days, the procedure should be repeated. After such a procedure, the mucous membrane becomes inflamed for a while, but now the chicken has immunity against laryngotracheitis.

Like any other disease, infectious laryngotracheitis will never visit your coop if you provide your chickens with the right diet and care. Your chickens should have clean water and good quality feed, and the coop should be dry and well ventilated. Do not forget about the disinfection of the chicken coop, chlorine-turpentine is used for these purposes.

Video "Prevention of viral diseases of chickens"

An experienced breeder will tell you how to deal with viral diseases of chickens, which include laryngotracheitis, in the video below, which is provided to your attention!

Laryngotracheitis is a disease resulting from the ingestion of a virus. Mostly chickens suffer from laryngotracheitis, especially in large farms. The virus infects the larynx and trachea, in rare cases, the bird may develop conjunctivitis or have problems with nasal breathing.

Outbreaks of this disease are recorded in all parts of the globe, regardless of climatic conditions. Most often, laryngotracheitis is ill at the age of 40 to 100 days.

Like any other disease, laryngotracheitis has its own distinctive symptoms, which include:

and whistling during breathing;
when squeezing the chest, the chicken begins to cough;
mucus may be discharged from the eyes and nose;
when examining the larynx, the veterinarian can detect swelling and redness, as well as pinpoint hemorrhages on the mucosa;
clots of sputum may be observed on the walls of the larynx.

Most often, the disease makes itself felt in the period of autumn and winter, as well as in early spring. When one bird is infected, the disease spreads quite quickly and after 7-10 days symptoms are observed in 60-70% of the population. In the absence of timely treatment, mortality is 15-20%.

It is important to note that laryngotracheitis has the following forms of leakage:

spicy;
preacute;
conjunctival;
atypical.

Acute laryngotracheitis

The disease in this form begins suddenly. Initially, symptoms are observed in just one bird, and after a week the disease spreads throughout the chicken coop. The acute form develops quite quickly and requires timely treatment.

Preacute laryngotracheitis

The disease in this form can last from 2 to 3 weeks. In this case, the symptoms are not as pronounced as in the acute form. At the end of the disease, the chicken recovers. In some cases, preacute laryngotracheitis may progress into a chronic form. In other words, the chicken will be sick for about a month with occasional improvements.

Conjunctival form

In this case, in addition to the general symptoms of laryngotracheitis, suppuration of the eyes joins the disease. Sometimes eye damage can be so severe that the chicken goes blind after recovery.

Atypical form

This form is almost asymptomatic. Usually, owners notice the disease only when the bird's condition worsens critically. At the same time, a sick chicken manages to infect almost the entire livestock of the chicken coop. Most often, the atypical form occurs in conjunction with other diseases.

How does the disease affect the chicken?

With a disease of laryngotracheitis, chickens become lethargic, their appetite is disturbed. Very often observed. In young chickens aged 20-30 days, the virus can infect. In this case, bacterial conjunctivitis develops. Normalization of the state of the bird occurs within 12-14 days with timely and proper treatment.

Causes of infection

The causes of infection are quite banal. Most often, the virus enters the chicken coop in the following way: when buying birds from an unverified breeder. You can buy a bird in which the disease is in the incubation stage. By planting a chicken with the rest, it automatically becomes the main source of infection.

In addition, you can purchase a bird that has already been ill, which is a source of virus isolation, but itself has a strong immunity to the disease. In simple words, in birds, the virus is transmitted exclusively from individual to individual.

Treatment Methods

Treatment of laryngotracheitis is carried out in the following ways:

in order to prevent complications in the form of bacterial infections from joining laryngotracheitis, the bird is soldered. More effective drugs are enrofloxacin, furazolidone and tetracycline;
carry out disinfection of the chicken coop using an aerosol spray of lactic acid;
drink vitamin complexes to increase immunity and protective reactions of the body;
for the prevention of healthy livestock is carried out.

Folk methods include:

providing chickens with access to green food;
frequent airing of the chicken coop in warm weather;
heating in winter.

Step-by-step instructions for using drugs

Enrofloxacin

It is used exclusively orally. To use the drug, it is diluted with water in a ratio of 5 ml per 10 liters of water and placed in a chicken coop instead of ordinary water. Usually the course of treatment does not exceed 5-7 days.

Furazolidone

It is important to note that an overdose of this drug can be fatal to a bird, which is why it is recommended to consult a veterinarian before starting the medication.

The drug must be given in a ratio of 3-5 mg per chicken, respectively, the larger the bird, the larger the dose of the drug it will need. The course of treatment with furazolidone lasts 8 days.

Tetracycline

The calculation of the drug is carried out according to the formula 50 mg of the drug per 1 kg of bird body weight. The drug is mixed with a small amount of food and divided into two portions: one of them is given in the morning, the second in the evening. Treatment with tetracycline continues for at least 5 days.

Consequences of the disease

Despite the fact that laryngotracheitis has a low mortality rate among chickens, however, the disease has its consequences.

After the chicken gets sick, it develops a strong immunity to the virus, but the virus itself continues to live in the body of the bird and is released into the air with respiration. Thus, even after recovery, the chicken remains infectious for other birds.

As for young chickens, their laryngotracheitis can cause blindness, frolicking due to conjunctivitis.

Infectious laryngotracheitis of birds - Larin - gotracheitis infectiosa avium. Synonym - tracheolaryngitis.

Infectious laryngotracheitis (ILT) is a contagious viral disease birds, characterized by damage to the mucous membrane of the upper respiratory tract and eyes in chickens, turkeys and pheasants.

Historical reference, distribution and economic damage. Infectious laryngotracheitis of birds was first reported in the United States in 1924.

In 1925, this disease was described by May and Titsler under the name tracheolaryngitis. Other American researchers (1925-1930) described it under the name infectious bronchitis. Later, the independence of these two diseases was proved, and a histological examination showed that with this disease, the larynx and trachea are mainly affected. The Special Committee on Diseases of Birds in the USA (1931) proposed that this disease be called infectious laryngotracheitis, which persists to this day. This disease covered almost all US states, and then spread to Europe, Australia, New Zealand and Asia.

In the USSR, infectious laryngotracheitis of birds was first described by R. T. Botakov in 1932 under the name of infectious bronchitis.

Later, A. P. Kiur-Muratov and K. V. Pachenko (1934), S. A. Polyakova (1950), T. S. Schennikov and V. A. Petrovskaya (1954) described it under the name infectious laryngotracheitis. Currently, infectious laryngotracheitis tends to spread and is registered in many farms of the Russian Federation.

The economic damage from this disease consists of losses as a result of the death of a sick bird, forced slaughter, a decrease in egg production, weight gain of birds, and huge costs for measures to stop the infection.

The causative agent is a DNA-containing virus of the herpes virus family (Herpesviridae), subfamily Alphaherpesviridae. Virions are spherical in shape, their diameter is 87-97 nm. The virus in the trachea and tracheal exudate persists for up to 86 days at a temperature of 2-4 ° C, indoors - up to 30 days, on the egg shell - up to 24-96 hours. In the absence of sanitation, the virus penetrates the egg white and yolk through the shell and can remain virulent up to 15 days. In frozen carcasses, the herpes virus retains its virulence for up to 19 months. In artificially infected fluff and grain feed, the virus survives up to 154 days. 1% alkali solution, 3% cresol solution inactivate the virus in 30 seconds.

The strains of the virus circulating in the country are antigenically related, but differ from each other in virulence and ability to be cultivated in cultures of chicken fibroblasts. Some strains have hemagglutinating properties.

epidemiological data. Under natural conditions, only domestic birds are susceptible to infectious laryngotracheitis, in particular chickens of all ages and sometimes pheasants, but in laboratory conditions it is possible to infect turkeys, ducks, but without showing symptoms of the disease.

Chicks between the ages of 3 and 9 months are susceptible to infection. Month old ILT chicks do not get sick, despite the fact that the virus grows on chick embryos, day old chicks are free from the disease.

The main source of infection is a sick and recovered bird.

The recovered birds are not susceptible to infection, but for a long time (up to 2 years) they are virus carriers and continue to release the virus into the environment. Infected birds constitute a major and long-term source of the virus because, like all herpes viruses, an infected animal continues to be a carrier and sheds the virus throughout its life.

The main routes of transmission of the virus are aerogenic (airborne) and contact. The respiratory organs serve as the gates of infection. The virus is transmitted from a sick bird to a healthy one mainly through infected air. From a dysfunctional poultry house, the virus with air masses spreads over a long distance - up to 10 km. It is possible to transmit the virus with slaughter products, down and feathers, incubation waste, containers, bedding, feed.

With the contact route, the entire livestock is re-infected in a short period, especially in broiler poultry farms.

The infectious laryngotracheitis virus is not transovarially transmitted.

The disease spreads in all seasons of the year, but more often in summer and autumn. The disease often occurs when poultry is kept in damp, dusty, gassed, in cold and drafty rooms, with insufficient air exchange, excessive planting of birds in poultry houses and the presence of diseases.

Mortality of birds with ILT averages 15%, sometimes it rises to 30-80% in acute course, higher than in Newcastle disease. The incidence in chickens up to 3 months of age can reach up to 90.5-100%, in chickens - up to 96.2%. In the conjunctival form of ILT, the incidence is 5-87%.

A person can also suffer from infectious laryngotracheitis, but the disease proceeds in a mild form with a favorable outcome.

Pathogenesis. The ILT virus, having penetrated into the upper respiratory tract, invades the epithelial cells of the mucous membranes of the larynx and trachea, and in some cases also other parts of the respiratory organs. In the affected cells of the epithelium, the nuclei rapidly multiply without dividing the cytoplasm. Soon there comes dystrophy of cells and their rejection into the lumen of the affected parts of the respiratory organs.

The reaction of the body to the penetration of the virus is expressed by a sharp blood filling of the vessels of the mucous membrane of the larynx, trachea, bronchi, lung parenchyma and the wall of the air sacs, swelling of the own layer of the mucous membrane of the upper respiratory tract, interstitial tissue of the base of the wall of the air sacs, cell-infiltrative and proliferative reactions, desquamation of the respiratory epithelium and effusion of exudate in various parts of the respiratory system.

Subsequently, the ILT virus penetrates into the blood through damaged vessel walls, where it is detected as early as 24 hours after infection.

Sharp desquamative processes of the respiratory epithelium (especially in the larynx and trachea) are the result of not only the direct action of the virus, but also the result of a violation of anatomical connections due to severe swelling of the own layer of the mucous membrane.

Increased vascular permeability, as well as their rupture due to mechanical causes (cough), lead to hemorrhages in the tissues and lumen of the larynx and trachea, which, in turn, greatly complicates the act of breathing, and blockage of these organs (their lumen) by caseous plugs leads to death birds as a result of asphyxia. The secondary microflora also has a certain influence on the severity of changes.

In the conjunctival corner of the eye, in addition to serous exudate, fibrinous-caseous masses accumulate, and sometimes turbidity develops.

Clinical signs. The incubation period for infectious laryngotracheitis averages 4-10 days (with fluctuations from 2 to 30 days).

The course of infectious laryngotracheitis can be fulminant, acute,

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With a fulminant course, the disease begins suddenly and spreads rapidly throughout the herd within a few days.

The incidence rate is extremely high and so is the mortality rate - it can be 50-70% of the total number of sick birds. Some individuals rarely show clinical signs of the disease for a period of more than 2-3 days before death, some of them die without first appearing symptoms. It is rare to see a clear loss of body weight and often the bird with the highest body weight is found to be sick. Respiratory symptoms appear immediately, without visible signs. Obvious breathing difficulties are observed, the bird stretches its head and neck, closes or covers its eyes and takes a long breath. This is accompanied by gurgling and wheezing. There is a spasmodic cough, with the head shaking violently in an attempt to remove obstructions in the trachea. When coughing, blood clots and mucus with blood inclusions are released, they can be seen on the walls and on the floor of the house. The head is usually cyanotic. Foamy discharge from the eyes and nostrils is sometimes observed.

In the subacute course in most birds, the disease progresses more slowly. Difficulty breathing, coughing, and other respiratory symptoms may last for several days before death. The incidence rate is still high, but the mortality rate is lower, it can cover from 10% to 30% of the diseased birds. This form of the disease may predominate throughout the period or occur at the end of an extremely acute outbreak.

The laryngotracheal form of the disease can be observed with fulminant and acute course in the first 5-7 days. The bird heard whistling, wheezing and croaking sounds, coughing. With this form, there is a partial or complete blockage of the larynx and trachea with fibrinous films, plugs and exudate. At the same time, the bird breathes with an open beak, which leads to a violation of the rhythm of breathing and asphyxia.

In a chronic course, the level of the disease in the herd can be 1-2%, but most of the sick birds invariably die from suffocation, sometimes after different periods of time, often after long ones. The main symptoms are: poor growth, coughing spasms and choking, if the bird is handled and in a state of excitement - discharge from the nostrils and eyes and a decrease in egg production.

Egg production decreases on the 9-10th day from the onset of the disease by 37.4-40% (Fig. 2). However, the quality of the eggs does not change.

In the chronic course, the disease also manifests itself in the conjunctival form more often in chickens aged 10-15 days, but it can also be in older ones. With the conjunctival form of the disease in chickens, photophobia, lacrimation, gluing of the eyelids and deformation of the palpebral fissure are observed. Hemorrhages are visible on the mucous membrane of the eyes, accumulations of fibrinous mass are noticeable under the third eyelid, atrophy of the eyeball occurs.

In some birds, clouding and ulceration of the cornea are noted, accompanied by partial or complete loss of vision.

The conjunctival form lasts from 20 days to 2-3 months and leads to exhaustion and increased culling of the bird.

With a mixed form of the disease, signs of all forms appear, but it proceeds more severely, and, as a rule, ends in an unfavorable outcome.

The atypical form of the disease proceeds with blurred clinical signs.

pathological changes. With the laryngotracheal form, the main changes are found in the larynx and trachea. The lumen of these organs in some birds is filled with various amounts of catarrhal or catarrhal-hemorrhagic exudate, some with blood clots; in other birds it contains fibrinous-caseous masses, often in the form of gray-yellow plugs, partially or completely blocking the lumen of the larynx, especially its gap. Caseous plugs are usually easily separated from the mucous membrane. The mucous membrane itself is sharply hyperemic, unevenly thickened and riddled with numerous dotted and striped hemorrhages, especially in the larynx and upper trachea.

In some enzootics of infectious laryngotracheitis, the hemorrhagic focus of inflammation is mild or completely absent. In these cases, catarrhal or fibrinous exudate is found in the lumen of the larynx and trachea, and in some birds, fibrinous-caseous plugs of a gray-yellow color are found.

Similar changes in the lungs often develop in a large percentage of cases in chickens infected in the trachea. With contact infection, catarrhal pneumonia is rarely observed.

The defeat of the air sacs in infectious laryngotracheitis is also relatively rare. However, when experimental method infections, especially with the intratracheal method, aerosacculitis occurs in a significant number of birds.

The wall of the air sacs in case of damage is diffusely or focally thickened, the vessels are overflowing with blood. In the cavity of the air sacs, a serous foamy exudate with fibrin clots or grains of fibrinous-caseous masses is found. It should be borne in mind that a large percentage of damage to the lungs and air sacs is often the result of an associated infection with respiratory mycoplasmosis and infectious laryngotracheitis.

Of the other changes found at autopsy, some researchers note catarrhal enteritis, cloacitis, lesions of the Fabricius bag and spleen hyperplasia.

The conjunctival form (atypical) of infectious laryngotracheitis can occur only with damage to the conjunctiva or in combination with the laryngotracheal form of the disease.

In some enzootics, the vast majority of birds show serous conjunctivitis. In this case, the conjunctiva is hyperemic, edematous, sometimes with petechial hemorrhages. Some birds note swelling of the eyelids, especially the lower one. In some chickens and chickens, there is an accumulation of fibrinous-caseous masses, gluing of the eyelids, clouding of the cornea, sometimes with the development of panophthalmitis.

histological changes. Histological examination of the larynx and trachea reveals pronounced edema and cellular infiltration of the mucosa and submucosa. Sometimes swelling of the mucous membrane destroys its normal structure, which leads to the presence of perivascular hemorrhages. 3-5 days after infection, a continuous cellular infiltration of small lymphocytes, histiocytes, plasma cells and eosinophilic leukocytes is noted in the larynx. However, characteristic is the detection in the nuclei of epithelial cells of the affected mucous membrane of the larynx, trachea and bronchi of intranuclear inclusions (acidophilic bodies) - virus-specific nuclear inclusions. They are found in cells with an enlarged nucleus. They can be round, sausage-shaped, or diplococcal in shape and occupy half of the cell nucleus. An uncolored zone is visible around the nuclear inclusion.

Immunity. The serum of birds that have recovered from infectious laryngotracheitis and hyperimmune birds contains specific virus-neutralizing antibodies. Recovered birds acquire strong immunity, which is transmitted to offspring through eggs.

Diagnosis. Epizootological data and symptoms of the disease in acute course are characteristic of infectious laryngotracheitis (ILT). However, the chronic course of ILT cannot be distinguished from other respiratory diseases.

To confirm the diagnosis, it is necessary to isolate the virus. The material for the study is fresh corpses, clinically sick birds (4-5 animals), exudate from the trachea, as well as scrapings of the affected mucous membrane of the larynx and trachea.

This is done in the following way:

Seeding of tracheal exudate on chorion-allantoic membranes;

Sowing on cell cultures;

RDP with tracheal exudate or with an infected chorion-allantoic membrane (CAO) using hyperimmune sera;

Detection of herpes viruses by electron microscopy: in tracheal exudate; growth at KhAO; immunofluorescence; Elisa using monoclonal antibodies to the ILT virus or ELISA;

Histological examination - detection of virus-specific intranuclear inclusions in the epithelium of the mucous membrane, Safe-Reed bodies.

Identification of the virus is carried out by a neutralization reaction (RN) on 10-11-day-old chicken embryos with specific antisera of chickens or rabbits.

differential diagnosis. Clinical signs of infectious laryngotracheitis are similar in some cases to other diseases of birds, therefore, when diagnosing them, it is necessary to exclude Newcastle disease, respiratory mycoplasmosis, infectious bronchitis, smallpox, contagious rhinitis, chronic pasteurellosis, hypovitaminosis A, ammonia blindness. Respiratory mycoplasmosis spreads slowly. Among the diseased, a large number of malnourished birds - "crackers", mostly young animals 5-7 months of age fall ill. At autopsy, lesions of the air sacs characteristic of respiratory mycoplasmosis - aerosacculitis - are found - their walls are thickened, opaque, covered with fibrinous films. Bird loss is negligible. When sowing on special nutrient media, the pathogen Mycoplasma gallicepticum is isolated from the air sacs and lungs; in retrospective diagnosis by enzyme immunoassay (ELISA), specific antibodies are isolated.

Infectious bronchitis of chickens is observed in them up to 30 days of age; proceeds mainly with the defeat of the bronchi, lungs and lower part of the trachea. Infection of 9-day-old chicken embryos causes the death of embryos at the end of incubation with characteristic signs of dwarfism, mummification without bacterial decomposition. The final diagnosis is established by the isolation of the virus in chicken embryos.

Smallpox is diagnosed by the presence of smallpox lesions on the comb, beards or diphtheria hard-to-remove deposits on the oral mucosa, as well as typical folliculitis that occurs after 4-8 days at the site of application of the virus-containing material. With an atypical form - for the isolation of the virus in chicken embryos.

The contagious rhinitis proceeds chronically; at the same time, a watery-mucous exudate is released from the nasal openings. There is no hemorrhagic and fibrinous inflammation, blood clots and caseous plugs in the trachea and larynx. In bacteriological examination, the causative agent of infection Bact is isolated. hemophillus gallinarum.

Chronic pasteurellosis. When sowing on ordinary nutrient media, the causative agent of this infection is isolated Pasteurella multocida, which is pathogenic for laboratory animals (white mice, pigeons, rabbits).

Hypovitaminosis A. To exclude it in the conjunctival form, it is necessary to examine liver samples for the content of vitamin A. Both sick chickens and those without clinical signs of the disease, but in contact with the sick, are examined. With hypovitaminosis A, hemorrhagic inflammation is not observed and there are no caseous-fibrinous plugs in the larynx and trachea. At the same time, changes are found mainly on the mucosa of the esophagus in the form of millet-like dense nodules, but histological studies and bioassay do not confirm infectious laryngotracheitis.

Ammonia blindness occurs when there is too much ammonia in poultry houses. When creating good ventilation, the disease quickly stops.

Treatment. Due to the fact that ILT causes significant economic damage to poultry farms, intensive searches are underway for drugs against this disease.

The most promising is the use of such drugs that can be used in any epizootic situation complicated by secondary infection.

Satisfactory results are obtained by using a 0.2% solution of sulfamethazan, 0.125% sulfazol with water for 2-6 days in a row, a solution of furacillin at a concentration of 1:5000 instead of drinking water and furazolidone 0.04-0.06% to the daily diet for 2-6 days.

Iodinol has therapeutic and prophylactic properties against ILT. The drug is recommended to be added to water and feed at the rate of 0.25-0.5 ml per head per day. Particularly good results were noted when giving iodinol at a dose of 0.5 ml per head together with 5 mg of nystatin. For the treatment of the upper respiratory tract in birds, irrigation of the mouth, nose and eyes with a 0.02% solution of gramicidin is recommended.

Positive results were obtained from the use of a mixture of penicillin (at a dose of 5-10 thousand units) in a 0.5% solution of novocaine with daily dacha for 2-3 days.

A. A. Zakomyrdin, V. E. Zuev (1978) proposed iodotriethylene glycol, which is an oily liquid, to combat infectious laryngotracheitis. Aerosol of iodine-triethylene glycol disinfects the ambient air in the poultry house, has a virucidal and bactericidal effect.

Aerosol apply a 30% aqueous solution of glycosan.

At the Department of Poultry Farming and Diseases of Birds MVA (B. F. Bessarabov, 1992), a method for the use of the drug isatizon against viral laryngotracheitis has been developed. It is an oily liquid of dark yellow color, bitter taste, with a specific odor, contains metisazon mixed with dimethyl sulfoxide and polyethylene glycol-400. Isatizon is recommended for the prevention and treatment of infectious laryngotracheitis in chickens.

For aerosol disinfection of the air environment in the presence of a bird, Glutex, Virkon C.

specific prophylaxis. For prophylaxis, live embryonic vaccines are used, i.e., a virus grown on chicken embryos, and cultural ones - on cell culture. In poultry farms are used:

Dry virus vaccine from the VNIIBP strain against ILT; w embryovirus vaccine against ILT;

Dry liposomal virus vaccine from the VNIVIP strain against infectious avian laryngotracheitis;

Combined dry vaccine against Newcastle disease (ND) and infectious avian laryngotracheitis (ILT);

Virus vaccine from the clone "NT" of the TsNIIPP strain.

Virus vaccines are applied by aerosol, cloacal, ocular, enteral.

Immunity occurs on the 7-10th day and persists throughout economic use birds. Vaccination is carried out only in disadvantaged farms, since in some cases up to 2% of chickens fall ill with ILT on the 8-15th day. Therefore, vaccinated chickens are reared in isolation.

Prevention and control measures. In a prosperous household. In order to prevent the occurrence of infectious laryngotracheitis in poultry farms, a set of measures should be taken in accordance with the instructions.

In a dysfunctional economy. When a diagnosis of ILT is established, the farm is considered unfavorable and the following restrictions are introduced in it: it is not allowed to take poultry, feed, equipment and inventory out of the farm, and during an acute outbreak, move the bird inside the farm.

When ILT occurs in a separate poultry house, all the birds from it are sent to a sanitary slaughterhouse. Carry out a thorough mechanical cleaning and disinfection of a dysfunctional poultry house. Litter after treatment of the premises with disinfectant solutions is subjected to biothermal disinfection.

In farms that are unfavorable in terms of ILT, the conditions for keeping and feeding birds are improved. Birds of different age groups are placed in territorially isolated zones, with the necessary veterinary breaks.

Import of breeding eggs and day old chicks is allowed; export of eggs to the distribution network after disinfection;

Completion of poultry houses and zones with healthy young animals of the same age is carried out at least 30 days after the acute course of the disease in other poultry houses of the economy.

Carefully observe inter-cycle preventive breaks with cleaning and disinfection of the premises.

Restrictions on a dysfunctional farm are removed 2 months after the last case of a case or slaughter of a sick bird, the final veterinary and sanitary measures and the absence of infectious laryngotracheitis virus isolation.

Export of birds to other farms to complete the parent flock is allowed no earlier than 6 months after the restrictions are lifted.

Disease prevention and control measures include a set of organizational measures, the use of chemicals that help disinfect indoor air in the presence of birds and partially inactivate the virus in the upper respiratory tract, and immunize birds with vaccines.

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