Prevention and control measures of common respiratory diseases in chickens

In recent years, the scale of the aquaculture industry has been expanding, showing a trend of large-scale and intensive development. This large-scale breeding model also makes the pressure of prevention and control of epidemic chicken diseases increasing, among which chicken respiratory disease is the most serious. As the symptoms of respiratory diseases in chickens are similar, and most of them are mixed infections, prevention and treatment is difficult, once the outbreak will bring huge economic losses to farmers. For this reason, the pro-agricultural network focuses on introducing several common respiratory diseases of chickens and the corresponding prevention and control measures, farmers may wish to have a look.

Common respiratory diseases in chickens include Newcastle disease, infectious bronchitis, infectious laryngotracheitis and so on. The specific symptoms and prevention and control are as follows:

I. Newcastle disease

1. Summary of symptoms of the disease

Newcastle disease, also known as Asian chicken plague or chicken plague, is a highly contagious infectious disease caused by avian paramyxovirus type I (Newcastle disease virus). Chickens that can infect chickens in various periods, non-immune susceptible chickens will have a very high morbidity and mortality. The main clinical symptoms were elevated body temperature, loss of appetite, yellowish green thin feces, mental depression, and different degrees of respiratory symptoms (cough, snoring, gasping, rale, etc.). Laying hens will show a decline in egg production, laying white shell eggs and deformed eggs. In the later stage of the disease, there may be a variety of neurological symptoms (twisting head, wing paralysis, etc.). The typical pathological changes were the proximal end of duodenum, the 2~3cm after the yolk remnant of jejunum, the beginning of ileum, and local mucosal congestion and swelling or purplish jujube-like ulcer. Tonsil swelling, bleeding, glandular stomach nipple bleeding. Follicular congestion, bleeding, deformity and liquefaction were seen in laying hens. Tracheal bleeding, mucus.

two。 Prevention and cure measures

Vaccine immunization is the main method to prevent and cure the disease. The commonly used vaccines in China are chicken Newcastle disease Ⅰ, Ⅳ live vaccine and oil emulsion inactivated vaccine.

Ⅰ vaccine is a moderately virulent vaccine, which is used to vaccinate chickens with two attenuated vaccines or chickens over 2 months old. Intramuscular injection has a certain pathogenicity to chicks. Immunity is produced at 3-4 days after vaccination, and the immune period is one year. Chickens vaccinated with this vaccine may have a certain immune reaction.

Ⅳ vaccine belongs to weak virulence vaccine. LaSota strain and its cloned strain (such as C30) are used in clinical application. Large and small chickens can be used, mostly using nose drops, eye drops, drinking water, aerosol and other methods of vaccination.

The oil emulsion inactivated vaccine is safe for chickens and can produce long-lasting immunity and will not spread the pathogen through the vaccine, but immunity can only be produced 10 to 20 days after injection. Chicken farms should work out immunization procedures and immune pathways suitable for their own farms according to the actual situation, and establish a regular immune detection system. The diseased chicken farm should be diagnosed in time and be immunized emergency. it can be treated with antiviral traditional Chinese medicine and antibiotics, and effective disinfection methods can be used to kill Newcastle disease virus in the environment.

II. Infectious bronchitis

1. Symptoms and overview of the disease

Infectious bronchitis is an acute and highly contagious disease caused by infectious bronchitis virus. Chicken is the only natural host of the disease. Chickens of all ages are susceptible, but the disease of chicks is the most serious. Especially chicks under 30 days of age are more susceptible. There is usually no death for more than 6 weeks, and the egg production and eggshell quality of laying hens decrease. The main types of infectious bronchitis are respiratory type, renal type, glandular stomach type and fallopian tube type.

Respiratory type mainly affects chickens within 2 weeks of age, commonly seen in sinus swelling, runny nose, tears, head shaking and so on, which is the main epidemic type in the early stage, and causes a serious decrease in egg production in infected chickens. Autopsy showed serous, catarrhal and yellow cheese-like exudates in the respiratory tract (trachea, nasal meatus and sinus). Cheese-like exudates can be seen in the trachea of dead chicks.

Kidney type is more common in 20-50-day-old chicks. Mild respiratory symptoms, such as rales, sneezing, coughing, etc., appear initially, but are more obvious only when it is quiet at night. After 1-4 days, the respiratory symptoms disappeared, the chickens suddenly developed a large number of diseases, and gradually aggravated within 2-3 days, showing anorexia, thirst, lethargy, huddling on the back, white feces in drainage, feces containing a lot of uric acid salt, dirty feathers around the anus, weight loss due to dehydration, cyanosis of chest muscles, severe dark and dry skin on the face and whole body, dry legs and neck. The peak of death was 10-12 days after onset, the death stopped at 21 days, and the mortality rate was about 30%. Typical autopsy symptoms: the kidney is enlarged and pale, showing a spotted kidney appearance.

The appearance of glandular stomach is extremely thin, and autopsy shows that glandular stomach is extremely swollen and globular.

The main manifestations of fallopian tube type were decreased egg production and tubal cyst in laying hens.

two。 Prevention and cure measures

Vaccine immunization is a more effective control measure, and the main vaccines used are attenuated vaccines such as H120, H52 and so on. In actual production, due to the large number of serotypes of infectious bronchitis, a single vaccine can only protect homologous strains, while heterosexual strains often have partial protection or no protection. Therefore, after immunization with H120 and H52, even if the antibody level is very high, it may fail because of the epidemic virus infection. Through a series of experimental studies, it is concluded that the combination of attenuated vaccine H120 nasal drip and multivalent inactivated vaccine is an effective method for the prevention and treatment of infectious bronchitis. Immune procedure: generally use H120 or Ⅳ H120 nasal drops or drinking water at the age of 1 week, and breeder farms often use imported vaccines of corresponding strains such as Ma5 to prevent and cure them. The mice were immunized twice with H52 at the age of 25 and 30 days. The mice were immunized with H52 or inactivated vaccine for the third time at the age of 120-140 days. It is suggested that the live vaccine and oil vaccine of infectious bronchitis variant strain 4x91 should be used in the epidemic area of renal infectious bronchitis.

Infectious laryngotracheitis

1. Symptoms and overview of the disease

Infectious laryngotracheitis is an acute respiratory infectious disease caused by infectious laryngotracheitis virus. Chickens of all ages can be infected, and adult chickens are the most characteristic. It occurs frequently in winter and spring, and the infection rate and mortality rate of the disease are high. The disease is characterized by dyspnea, coughing and coughing up mucus containing blood, and hemorrhagic-necrotizing inflammation of the mucosa of the throat and trachea. Clinically, it is mainly divided into laryngotracheitis type and conjunctivitis type. Laryngotracheal inflammatory type: characterized by dyspnea, raising head and neck, coughing blood sputum when diseased chicken coughs and shakes its head. The pathological changes were swelling, hyperemia, bleeding and even necrosis of the larynx and trachea. The trachea was often filled with blood clots, mucus and yellowish caseous exudates. Conjunctival type: mainly serous conjunctivitis, characterized by conjunctival edema and hyperemia. There are some diseased chicken-eyed faces, especially edema in the face at the moment. Some will have fibrinous conjunctivitis and corneal ulcers. Sometimes mixed infection with larynx and trachea diseases.

two。 Prevention and control measures

Adhering to strict biosafety and epidemic prevention measures is an effective way to prevent and control the epidemic of this disease. As infected chickens are one of the sources of infection of the disease, susceptible chickens must not come into contact with cured chickens or chickens of unknown origin. Immune prevention and treatment: mainly with attenuated vaccine eye and intensity vaccine smear anus. Treatment: antiviral drugs to strengthen the treatment of antibiotics such as liomycin (to prevent secondary infection), while the use of antiasthmatic drugs to relieve symptoms.

IV. Infectious rhinitis

1. Symptoms and overview of the disease

Infectious rhinitis (IC) is an acute upper respiratory disease of chickens caused by Haemophilus parvidis. The main clinical symptoms are inflammation of nasal cavity and sinus, runny nose, sneezing, facial swelling and conjunctivitis. Chickens of any age are susceptible, but young chickens are generally not too serious. Chickens at the age of 8 and 12 weeks are the most common. Most of them occur in the cold season of autumn and winter. In a typical case, the pathological changes were serous, mucinous or suppurative inflammation of the nasal cavity, paranasal sinuses and conjunctiva. The paranasal sinuses and infraorbital sinuses accumulated yellow, sticky purulent secretions or cheese-like substances in the longer course of the disease, and the diseased chickens showed mild respiratory symptoms and kept shaking their heads.

two。 Prevention and cure measures

First of all, strengthen the feeding and management. The chicken house must be well ventilated, and the chickens should not be overcrowded to prevent all kinds of stress. Secondly, vaccination should be done. The vaccine for this disease is mainly inactivated vaccine, which is generally vaccinated at the age of 70 days. Sulfonamides are the first choice for the treatment of the disease in sick chickens. The effect is remarkable, but it is easy to relapse, so it can be followed by a course of erythromycin treatment.

5. Chronic respiratory diseases

1. Symptoms and overview of the disease

Chronic respiratory tract is a chronic respiratory disease caused by Mycoplasma gallisepticum infection, which is characterized by cough, runny nose, rale, wheezing, sinus swelling and facial swelling. Although the mortality rate was low, the affected chickens grew slowly, the egg production decreased and the feed reward was low. It can happen all the year round, with changeable climate and frequent occurrence in cold seasons. The symptoms of autopsy are a large number of sticky secretions in the nasal cavity, trachea and bronchi. In the early stage, the airbag was slightly turbid, edema and opaque, and cheese-like substances were formed on the airbag with the prolongation of the course of the disease. It is often mixed with viral diseases and other bacterial diseases, such as colibacillosis, avian influenza, Newcastle disease, infectious bronchitis and so on.

two。 Prevention and cure measures

The prevention and treatment of chronic respiratory disease is mainly carried out by purifying breeder chickens, reducing stress inducing factors, vaccination and drug treatment.

a. Breeder purification

Chronic respiratory disease is mainly transmitted through vertical transmission, once the infection is difficult to cure, at the same time, the disease will also induce other diseases. Therefore, the focus of prevention and control is to purify breeder chickens.

b. Elimination of stress-inducing factors

At present, the infection rate of the disease is very high in chickens in China, as long as there are stress-inducing factors, especially pay attention to the control of inducing factors, such as poor ventilation, dirty air, low or sudden high and low temperature in the house, excessive density, the occurrence of virus disease and so on.

c. Vaccination

In China, there are mainly attenuated vaccine and inactivated vaccine, the former is mainly used for commercial chickens and layers, the latter is mainly used for breeder immunity.

d. medication

The commonly used drugs are doxycycline, tylosin, enrofloxacin and so on. However, Mycoplasma chicken can infect the airbag to form cheese-like substance, so it is difficult for drugs to reach this site, so that the pathogen can survive in the body for a long time, and it is easy to recur, so once the disease occurs, chickens must adhere to long-term medication, rotation of drugs and combined use of drugs.

The above is the introduction of the symptoms and prevention measures of common respiratory diseases in chickens brought by the pro-agricultural network. We can see that most of the respiratory diseases are infectious to a certain extent, so once the losses occur are very huge. Farmers must strengthen management in the process of breeding to prevent the emergence of such diseases.