Laboratory diagnosis of infectious laryngotracheitis virus in birds. Infectious laryngotracheitis of chickens: treatment and symptoms. Symptoms of an acute form of the disease

Vaccination is carried out either when the bird enters the farm, or when it reaches the age of 30-60 days. Birds older than 60 days are vaccinated once; if vaccination is carried out earlier, then the vaccination should be repeated after 20–30 days.

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

Infectious laryngotracheitis (ILT) is a contagious viral disease of 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Historical reference, distribution and economic damage.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 birds are 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 hears 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 disease rate 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, with the experimental method of infection, 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 metisozone 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 7th-10th day and persists throughout the entire economic use of the bird. 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 isolation of the infectious laryngotracheitis virus.

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.

Infectious laryngotracheitis(ILT) is a viral respiratory disease of chickens, accompanied by damage to the mucous membrane of the trachea, larynx, conjunctiva of the eyes. In a short time, the disease can cover the entire poultry population on the farm.

The causative agent of laryngotracheitis is a highly virulent virus. It multiplies mainly in the upper respiratory tract, as well as in the cloacal mucosa, where it is usually found.

The disease is accompanied by a long or lifelong virus carrier. But recovered birds acquire almost lifelong immunity.

In our country, ILT (under the name "infectious bronchitis of chickens") was first described by R. Batakov in 1932. This disease occurs in many countries of the world.

In Russia, it is registered mainly in farms with industrial production of poultry.

Attention!

The damage from this disease consists of losses as a result of the death of a sick bird (up to 15-30%), forced slaughter, reduced egg production and weight gain.

Source of the causative agent of laryngotracheitis- a sick and ill bird. Transmission of the virus is also possible through contaminated egg shells.

From one farm to another, the infection enters with sick birds, as well as with infected feed and drinking water, care items and people's clothing.

Infection occurs mainly aerogenically and through contact of healthy chickens with sick ones.

The incubation period of the disease lasts 6-10 days and depends primarily on the virulence of the virus, the natural resistance (stability) of the bird and the conditions of its maintenance.

There are acute, subacute, chronic and asymptomatic forms of the disease, and according to the clinical picture, laryngotracheitis is divided into laryngotracheal and conjunctival (the latter is most often observed in chickens).

In the acute form, the bird has difficulty breathing, and as a result, fibrinous-hemorrhagic inflammation of the trachea.

Often laryngotracheitis accompanied by rhinitis, sinusitis, conjunctivitis. In laying hens, egg production drops sharply - up to 30-50% (depending on the severity of the disease). Every second chicken can die from suffocation.

Clinical signs in the subacute form of the course of the disease are often erased. Conjunctivitis, coughing, sneezing are observed. The course of the disease is complicated by overcrowding of birds, dampness, poor ventilation of the room, and inadequate feeding of birds.

ILT often occurs in combination with smallpox, respiratory mycoplasmosis, colisepticemia, and infectious bronchitis. With a mixed infection, the disease torments the bird more severely and is accompanied by a large waste of it.

Laryngotracheal form more often proceeds super-acutely and sharply. At first, individual birds get sick, as the virus accumulates in the external environment and its virulence increases, the number of sick people becomes more and more, and after 7-10 days all the birds in the house can fall ill.

A sick bird is inactive, sits ruffled, with closed eyes. Her appetite is reduced or absent altogether.

Then a cough appears, the mucous membrane of the larynx and trachea swells and becomes reddish.

Mucous exudate accumulates in the lumen of the trachea, which makes breathing difficult and leads to suffocation.

Sick bird breathing with open beak.

When inhaling, she stretches her neck up and forward, while inhaling and exhaling, a peculiar whistling or wheezing sound is heard (in this case they say “the bird sang”).

These sounds are clearly distinguishable, especially at night. Light pressure on the larynx or trachea causes a painful reaction in the bird.

The conjunctival form is usually characterized damage to the eyes and nasal mucosa.

At first, a sick bird exhibits photophobia, chickens hide in dark corners.

The third eyelid swells slightly and protrudes from the inner corner of the eye, somewhat covering the eyeball. The eye gap is deformed.

As the disease progresses, the eyelids swell, and a serous exudate is released from the eyes, which foams from frequent blinking. The swelling of the eyelids gradually increases and the eye closes.

But, I repeat, a bird that has been ill with infectious laryngotracheitis acquires lifelong immunity.

To prevent laryngotracheitis VNIIBP and VNIIVViM vaccines are used, which are rubbed into the mucous membrane of the cloaca, instilled into the conjunctiva, or applied by aerosol. With aerosol vaccination, immunity develops after 4-5 days and lasts up to 1 year.

To prevent a secondary (secondary) infection, aerosols of chemicals are used (crystalline iodine powder and aluminum powder, iodinol, iodotriethylene glycol).

In disadvantaged farms, mandatory vaccination against ILT is carried out. It is very important to follow the vaccination schedule. For the formation of immunity, the bird is vaccinated twice, and the second vaccination should be carried out no later than 4 weeks before the start of oviposition.

According to the instructions, only clinically healthy birds are subject to immunization, weak and sick young animals are culled immediately. Of all the ways of using vaccines for ILT (cloacal, aerosol, on the conjunctiva of the eye, with water), the most reliable is the application of the vaccine on the conjunctiva of the eye.

Clinically healthy birds are vaccinated by aerosol with an interval of 16-20 days, ocularly - 20-30 days, and cloacally - 30 days.

In addition, it is important to timely disinfect indoor air, preferably in the presence of birds. For raising chickens, it would be nice to allocate an area isolated from the area where adult birds are kept.

There are no effective drugs for laryngotracheitis yet.. To reduce the death of birds and prevent a decrease in egg production, antibiotics are often used in combination with furazolidone and trivitamin, dioxidine (indoors), nigras (in the form of an aerosol).

When infectious laryngotracheitis occurs import and export of birds from the farm is prohibited.

Eggs obtained from hens in a dysfunctional poultry house can only be used for food purposes.

All sick and suspicious birds are slaughtered. Egg incubation is stopped for 1-2 months.

Periodically, 1 time in 7-10 days, the premises are treated with chlorine turpentine (in the presence of a bird).

Hot solutions of sodium hydroxide or formaldehyde, clarified bleach solution, formalin solution can be used for disinfection.

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Source: http://dom-krolika.ru/domashniaia-ptica/42-laringotraheit-domashnei-pticy/

How to treat laryngotracheitis in chickens: photo, video

Laryngotracheitis is a dangerous viral disease of chickens, which often leads to death. The cause of this disease is the herpes virus, which is very resistant to the external environment and has a long duration of existence, both in the body of the carrier and outside of his body.

There are three main forms of laryngotracheitis:

• Acute (death in more than 10% of sick individuals)
• Hyperacute (death in more than 50% of sick individuals)
• Chronic (death in more than 60% of sick individuals)

This disease affects not only chickens, but also other poultry, as well as wild pigeons. The virus is also dangerous to humans, as it is transmitted through contact with sick birds. In humans, laryngotracheitis is manifested by damage to the larynx, skin of the hands, or bronchitis.

This disease is dangerous because it is transmitted by airborne droplets, so it spreads very quickly. In one day, over 70% of birds living in one chicken coop can become infected.

Attention!

The most dangerous period is the cold season. Since low air temperature prolongs the life of the virus, slowing down its metabolic processes.

Most of all, chickens and young hens, aged from one to eight months, are susceptible to this disease. If they survived and succumbed to treatment, then such individuals are considered infectious for several more years and cannot exist in the same room with their relatives.

Clinical picture

The symptoms of this disease are very pronounced. Development occurs quite rapidly and already on the first day after infection, the first symptoms appear.

Initially, inflammatory processes are observed in the mucous membranes of the throat and nose of birds, later conjunctivitis develops. Chickens stop pecking food due to swelling of the larynx, during this period, the eyes begin to water heavily.

Establishing a diagnosis can be quite easy and fast. If you react in time and start treatment at the initial stage of the disease, then the birds can be cured in less than a week. In more severe cases, treatment may be delayed for more than 14 days.

Laryngotracheitis, depending on the form of the course, has different symptoms, namely:

1. Super sharp form. Basically, it occurs abruptly and develops very quickly. All symptoms are pronounced:

• Birds begin to wheeze, breathing is heavy
• Visually resembles asthma attacks
• Violent cough, sometimes with blood
• Due to suffocation, the bird constantly makes head movements
• Apathy
• immobility
• Lack of appetite
• Complete refusal to eat
• Often standing with eyes closed
• Condition worsens at night

If there are a large number of infected individuals in the chicken coop, then on the walls and floor, one can notice abundant mucous secretions. If measures are not taken in time and treatment is not started, then after a couple of days the chickens will begin to die. With the further development of the disease, it will be almost impossible to cure them.

1. Sharp form. It starts more calmly than the super-acute form. It is characterized by the following symptoms:

• Lack of appetite
• immobility
• Apathy
• Most of the time, chickens sit with their eyes closed.
• Breathing is heavy through the beak
• Significant swelling of the larynx
• Wheezing when breathing

If the birds do not provide timely assistance, then they die from asphyxia. The reason for this is the complete obstruction of the larynx or trachea, caused by severe inflammation and swelling.

1. Chronic form. It occurs only in cases where the acute form of the disease was not completely cured, or if the chickens survived without treatment, thanks to a strong immune system.

In most cases, this form of the disease proceeds calmly and is almost asymptomatic. Which is misleading and gives reason to consider birds healthy.

As a rule, the symptoms can appear only before the death of the chickens, they are the same as in other forms of the disease.

Another manifestation is conjunctivitis, and in younger birds, photophobia develops. This can lead to complete loss of vision.

Pathological changes

In case of infection with laryngotracheitis, significant pathological changes are observed in the body of chickens. They are especially noticeable if you examine the larynx and trachea. Strong inflammatory processes are visible, which are manifested by redness and swelling, with minor hemorrhages.

Also, in the trachea, the formation of fluid, mucous or serous, is observed.

In more advanced cases, a plug forms in the larynx of the bird, which blocks the supply of oxygen.

On the tongue and oral mucosa, the formation of a light plaque is noticeable.

If the disease occurs with the manifestation of conjunctivitis, then the birds experience redness and swelling of the affected eye. This leads to a profuse discharge of tears, sometimes with an admixture of pus. The eyesight of chickens is very affected.

Diagnosis of the disease

In order to make an accurate diagnosis, you need to consult an experienced veterinarian.

He will draw final conclusions based on the clinical picture, as well as by conducting the necessary laboratory tests.

For this, both live chickens, which are presumably infected, and corpses are needed.

It is important to exclude other diseases that are symptomatically very similar to laryngotracheitis. In this case, special samples are taken to detect antibodies in the body of birds.

After all the manipulations and confirmation of the diagnosis, it is necessary to immediately begin treatment, following all the recommendations of the veterinarian.

Treatment

Unfortunately, there is no special drug that could cure birds of laryngotracheitis. Therefore, first of all, drug therapy in the form of antibiotics is used.

They help the bird's immune system fight the disease by reducing the activity of the virus in the body.

Important, in the treatment of laryngotracheitis, is the use of special drugs, such as biomycin and streptomycin.

Of great importance in the fight against this disease, has a proper and balanced diet. It should be saturated with vitamins (especially A and E), as well as various micro and macro elements.

In the diet of chickens, not only cereals should be present, but also fresh herbs, vegetables, root crops and table waste.

It is necessary to give special supplements, in the form of bone and fish meal.

It is necessary to ensure that all the products that chickens eat are only fresh and of high quality.

The water regime plays an important role. Therefore, it is necessary to ensure the constant access of birds to clean drinking water. Various vitamin supplements can be added to it.

Also, when the first symptoms are detected, sick birds should be immediately isolated. The chicken coop needs to be completely disinfected. She is also subject to feeders, drinkers, work tools and the farmer's clothes, in which he works near the chickens.

It is important to note that birds that have been ill with laryngotracheitis and are completely cured acquire long-term immunity to the pathogenic virus. This prevents re-infection.

Antibodies to the disease begin to form after the second week, from the moment of infection. They remain in the blood serum for about three months.

Immunity itself has a duration of up to eight months.

Preventive measures

Of course, it is much easier to prevent infection with a serious disease than to treat it later.

The main method of prevention of laryngotracheitis is a special vaccination. It is used when new birds are imported or when there is an outbreak on the farm.

There are few vaccines available. They give the best result when instilled in the eyes, the cloacal method or the feeding of birds is less effective.

For adults, the vaccine is administered only once. For chickens under two months old, it is administered twice, with an interval of about 20 days.

As for the vaccine itself, in our time there are only two types:

1. Chicken embryo vaccine. It protects the body from the virus quite well, but at the same time, it has a number of serious complications.
2. Cell culture vaccine. Less effective than the first type. But it doesn't give any side effects.

Also, in order to prevent any diseases, it is important to monitor the quality of eggs that are selected for incubation.

When new birds are introduced to the farm, they must be carefully examined and quarantined for several weeks.

It is necessary to comply with all the rules of sanitary and hygienic standards for keeping chickens. Birdhouses should be spacious and clean. Good ventilation will help clean the air not only from germs, but also from various fumes.

Attention!

It is important to maintain the correct thermal regime in the habitat of chickens. This has a positive effect on both the health and productivity of birds.

You should always remember about proper and balanced nutrition. It is it that is the source of all the necessary nutrients that strengthen the immune system of chickens.

In the event that preventive measures have not brought the desired result and a significant infection of the poultry population has begun, it is recommended to kill all the chickens in the poultry house in which the epidemic has occurred. If the spread of the disease has not stopped, you need to kill all weakened individuals in other chicken coops.

Slaughter should take place exclusively under the supervision of a veterinarian, in compliance with all sanitary and hygienic rules. After that, the tool, work clothes and the place of slaughter must be thoroughly disinfected.

During the epidemic, the economy is considered unfavorable. At this time, the export of poultry and eggs is prohibited, especially for sale.

Since this can provoke a massive infection of not only birds, but also people.

Work equipment clothing, feeders and drinkers that have been in contact with sick individuals cannot be reused. It is best to dispose of them if possible.

After two months, after the last slaughter of a sick bird and with the implementation of all preventive measures, the farm is removed from quarantine and returns to normal activities.

In the future, the health and life of the inhabitants of the farm depends on the care and responsibility of the owner.

Infection occurs through sick and recovered individuals. All types of chickens, pigeons, turkeys, pheasants are susceptible to the disease. Chickens are most commonly infected with the virus.

An ill bird carries the virus for up to 2 years. The spread of laryngotracheitis occurs due to poor conditions for keeping birds: poor ventilation, crowding, dampness, inadequate diet.

What is infectious laryngotracheitis in chickens?

For the first time laryngotracheitis was registered in 1924 in the USA. American researchers May and Titsler described it in 1925 and named it laryngotracheitis.

The disease was later described as infectious bronchitis. After the 1930s, laryngotracheitis and infectious bronchitis were recognized as separate diseases.

In 1931, the disease of the larynx and trachea was proposed to be called infectious laryngotracheitis.

This proposal was made by the Committee on Diseases of Birds. By that time, the disease had spread everywhere, including in the USSR.

In our country, infectious laryngotracheitis was first described in 1932 by R.T. Botakov. Then he called the disease infectious bronchitis. A few years later, other scientists described the disease under its modern name.

Today, chickens are infected with laryngotracheitis in many regions of Russia, causing enormous damage to personal and farm households. Birds die, their egg production and weight gain decrease. Poultry farmers have to spend a lot of money on stopping the infection and acquiring young animals.

Pathogens

The causative agent of laryngotracheitis is a virus of the family herpesviridae, which has a spherical shape.

Its diameter is 87-97 nm. This virus can hardly be called persistent.

For example, if there are no chickens in the house, he dies in 5-9 days.

In drinking water, the virus persists for no more than 1 day. Freezing and drying it is preserved, and under the influence of sunlight, the virus dies in 7 hours.

Kerazole alkali solutions neutralize the virus in 20 seconds. On the shell of eggs, it can last up to 96 hours. Without sanitation, it penetrates inside the egg and remains virulent for up to 14 days.

Up to 19 months, the herpes virus remains active in frozen carcasses and up to 154 days in grain feed and feathers. In the cold season, the virus lives in the open air for up to 80 days, indoors - up to 15 days.

Symptoms and forms of the disease

The main sources of the virus are sick and recovered birds.

The latter do not get sick after treatment, but 2 years after the illness they are dangerous, since they release a virus into the external environment.

Infection occurs through infected air.

The disease also spreads with slaughter products, feed, containers, feathers and down.

In this case, the infection of the entire livestock occurs in the shortest possible time. More often the disease spreads in summer and autumn.

The course and symptoms of laryngotracheitis in chickens depend on the form of the disease, the clinical picture, and the conditions in which the birds are kept.

The incubation period of laryngotracheitis is from 2 days to 1 month. Let us consider in more detail the main signs of the disease in each of the three forms.

Super sharp

Often occurs where the disease has not previously manifested itself. When exposed to a highly virulent infection up to 80% of chickens can become infected in 2 days.

After infection, the birds begin to breathe with difficulty, eagerly swallow air, stretching their body and head.

Some chickens develop a strong cough, accompanied by bloody expectoration.

Because of the rolling suffocation, the chicken shakes its head violently, trying to improve its condition.

In a poultry house where sick chickens are kept, tracheal secretions can be seen on the wall and floor. The birds themselves behave passively, more often they stand in solitude, closing their eyes.

The course of hyperacute laryngotracheitis is accompanied by characteristic wheezing, which is especially audible at night.

If poultry farmers do not take action, after a couple of days of illness, chickens begin to die one after another. Mortality is high - more than 50%.

Acute

In the acute form, the disease does not begin as suddenly as in the previous form.

First, a few chickens get sick, after a few days, others. A sick bird does not eat, all the time it sits with its eyes closed.

The owners note lethargy and general oppression.

If you listen to her breathing in the evening, you can hear spitting, whistling or wheezing sounds that are not characteristic of a healthy bird.

She has a blockage of the larynx, which leads to impaired breathing and breathing through the beak.

If the larynx is palpated, it will cause her to cough violently. Inspection of the beak will allow you to see hyperemia and swelling of the mucous membranes. White spots may be visible on the larynx - curdled discharge.

Timely removal of these secretions can help save the life of chickens. After 21-28 days of illness, the rest may die from asphyxia due to blockage of the trachea or larynx.

Chronic

This form of laryngotracheitis is often a continuation of acute. The disease proceeds slowly, characteristic symptoms appear before the death of birds. 2 to 15% of birds die. People can also infect a bird with this form due to unsuccessful vaccination.

Often there is a conjunctival form of laryngotracheitis, in which the eyes and nasal mucosa are affected in birds.

It is more common in young animals up to 40 days of age. With this form of the disease, the palpebral fissure is deformed in chickens, they begin to have photophobia, and they try to hide in a dark corner.

With a mild form, chickens recover, but they may also lose their sight.

Diagnostics

The disease is confirmed after autopsy and laboratory tests.

To conduct a virological study, fresh corpses, exudate from the trachea of ​​dead birds, as well as sick birds are sent to specialists in the laboratory.

There, the virus is isolated on chicken embryos and subsequent identification is carried out.

A bioassay on susceptible chickens is also used.

In the process of diagnosis, diseases such as Newcastle disease, respiratory mycoplasmosis, smallpox, infectious bronchitis are excluded.

Treatment

As soon as the disease is diagnosed, it is necessary to be taken for treatment.

There are no specific drugs for laryngotracheitis, but symptomatic treatment can help sick birds.

Antibiotics can be used to reduce virus activity and biomycin to reduce chicken mortality.

Also, for the treatment of infectious laryngotracheitis of chickens, as well as other birds, veterinarians use streptomycin and trivit that are administered intramuscularly.

Prevention

Disease can be prevented in a variety of ways. Firstly, it is necessary to periodically disinfect the premises in which the birds live.

However, they should be there. For disinfection, mixtures of chlorine-turpentine preparations, aerosols containing lactic acid are recommended.

Secondly, you can use vaccination. In regions with frequent outbreaks of the disease, a live vaccine is injected into the body of birds through the nasal passages and infraorbital sinuses.

There is some probability that under certain conditions these birds can become active carriers of the virus, so this measure is only a point prevention.

The vaccine can be rubbed into the feathers of birds or introduced into drinking water.

There is a vaccine specially developed for chickens from the strain " VNIIBP". Usually, chicks are vaccinated from the age of 25, taking into account the epizootic situation.

If the economy is prosperous, aerosol vaccination is carried out. The vaccine is diluted according to the instructions and sprayed in the bird habitat.

After that, a temporary deterioration in the condition of the birds is possible, which disappears after 10 days. The resulting immunity lasts for six months.

Another vaccination option is cloacal. With the help of special tools, a virus is applied to the mucous membrane of the cloaca and rubbed for some time. After a few days, the procedure is repeated. After vaccination, the mucous membrane becomes inflamed, but after that a strong immunity is developed.

In a farm where laryngotracheitis is diagnosed, quarantine is introduced. It is not allowed to export chickens, equipment, feed, eggs.

If the disease manifests itself in one poultry house, all chickens are sent to a sanitary slaughterhouse, after which the premises are disinfected and biothermal disinfection is carried out. In poultry farms, entry and exit of people from the territory is allowed after careful sanitization of shoes.

Thus, laryngotracheitis is a dangerous infectious disease of chickens, which every poultry farmer should know about. By recognizing the disease in time, laying hens can be saved from suffering and premature death.