Malignant catarrhal fever - the pathology of the viral nature of cattle and other ruminants. Manifested by the processes of inflammatory nature of the mucous organs of the gastrointestinal tract, respiratory tract and conjunctiva. The VCL virus also causes damage to the central nervous system. It is quite rare, usually occurs in isolated cases, numerous diseases are possible in winter and with a decrease in immunity.
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Causes and spread of the disease
The pathogen belongs to the family of herpes viruses. It was first isolated from the blood of wildebeest in the 53rd year. The first descriptions of pathology refer to the beginning of the 19th century; in Russia, pathology was recorded at the end of the same century. Currently, the infection is not widespread and the main outbreaks of pathology are observed in the UK. In our country, isolated cases are recorded.
Older cattle are susceptible to the disease. Calves are extremely rare, probably due to the presence of colostral immunity. The most severe course occurs in bulls for more than 8 years. In females, the pathology is also less pronounced.
Wild artiodactyls usually act as carriers of the malignant catarrhal fever virus. Laboratory development was able to achieve the development of the disease in rabbits, guinea pigs and mice.
In the external environment, the VCL virus is excreted with effusions from the nasal passages and the conjunctiva. Infection occurs only through direct contact - the virus is extremely unstable in the external environment, and the possibility of insect pathogen transfer is also not confirmed.
Preservation of the virus in nature occurs in the body of wild ruminants, as well as in domestic small ruminants. The greatest number of outbreaks was observed with joint grazing and keeping of cows and sheep. There are also cases of disease of cattle kept separately, so the carriers can be other organisms, most likely rodents.
The development of the disease occurs in a damped curve. At the beginning of the outbreak, a severe lethality is observed. Usually, pathology manifests itself in the winter period among the exhausted old animals kept in poor conditions.
Pathology is manifested in several clinical forms, but it is usually characterized by catarrhal inflammatory processes in the mucous membranes of the digestive tract and the respiratory tract. For the differentiation of pathology, it is recommended to conduct a diagnostic autopsy and laboratory examination of pathological material.
Clinical picture ZKG
After penetration, the pathogen of malignant catarrhal fever is in an incubation state for another 2-10 months. After that, the disease is rapidly developing (chronic cases are extremely rare). Forms of the disease:
- damage to all organs (the most common)
- intestinal (inflammatory processes of the digestive organs),
- respiratory (inflammation of the nose, mouth, and conjunctiva),
- atypical - focal lesions of the skin on the head.
The first sign - a rapid temperature rise to 42 degrees. The exhausting febrile process is observed all the time with slight fluctuations. There is a strong oppression, the cows become fearful (less often aggressive). Symptoms of damage to the nervous system begin to manifest themselves - a precarious gait, tremor, convulsions, and a coma. Breathing and pulse quickened, appetite suppressed, increased thirst.
Inflammatory processes are manifested from the second day of the disease. The first are the mucous membranes of the mouth and nose, followed by conjunctivitis:
- fear of the light
- conjunctival swelling,
- local redness,
- develops keratitis, sores on the cornea.
From the nasal passages stand out mucous discharge, gradually turning into purulent. With inflammation of the larynx, signs of suffocation are noted, then the bronchi and lung tissue are involved - bronchitis, pneumonia, passing from catarrhal to croupous, accompanied by painful cough.
The defeat of the gastrointestinal organs is manifested by debilitating dyspepsia, fecal masses with a fetid odor, they contain impurities of fibrin, dead tissue of the intestine. This form of pathology is usually fatal within a week.
Pregnant cows undergo an abortion. Inflammation in the reproductive organs are rare. The atypical form is characterized by an abrupt cessation of the symptoms, but exacerbations are possible in animals.
Laboratory research methods
The clinical picture is peculiar to a large number of infectious and non-contagious diseases, therefore, for the differentiation of malignant catarrhal fever, it is necessary to take samples of pathological material from sick cattle. For diagnosis, use PCR, the reaction of binding the complement and the study of histological sections. If other diseases are suspected, a diagnosis can be established by excluding plague, foot and mouth disease, leptospirosis, or other diseases of cattle.
The corpse of a cow is in a state of exhaustion, subject to rapid decomposition. The hind limbs and croup are stained with feces, around the nasal passages of the pus crust. The coat is ruffled. There are fetid outflows from the mouth.
At autopsy, such changes are noted:
- the blood vessels are filled with thick dark blood,
- point bruises are found on the subcutaneous fatty tissue,
- swollen lymph nodes, signs of inflammation are visible on the incision,
- fibrin deposits and ulceration on mucous membranes,
- the capsule from the kidneys is poorly removed, under it dotted hemorrhages are found,
- enlarged spleen
- flabbiness of the heart muscle.
With the fulminant form of the disease, pathological changes are hardly noticeable. Usually marked flaccidity of the myocardium with elements of degeneration. Also visible is swelling of the liver and damage to the lymph nodes.
To date, no specific treatment has been developed for the treatment of malignant catarrhal fever. Therefore, the basis of treatment is based on increasing resistance and preventing the development of associated diseases.
It is useful to prescribe antibiotics to prevent bacterial complications - especially often develop streptococcal bronchopneumonia, gastroenteritis. With the same purpose used nitrofurans, sulfa drugs.
To normalize the nervous system prescribed sedatives. In severe cases of seizures and seizures, anesthesia should be performed - use of Rometar, Rompoun, intravenous injections of alcohol.
The basis for the treatment of this disease is the creation of better conditions for housing and feeding to increase the immune response of the cow.
A sick cow should be placed in a separate dry room with weakened lighting. In the diet add only juicy and soft food with high nutritional value. Water is not limited, it is recommended to acidify it.
Measures for the prevention and elimination of the disease
Sustained immunity to the CK is not formed. With experimental infection, an infection process develops already a couple of weeks after clinical recovery. The pathology vaccine has not been developed. Therefore, preventive measures are based on preventing the disease from entering the economy and its distribution - quarantine of purchased livestock, regular disinfection of premises.
When a cow has progresses, it seizes the digestive system. So the animal loses its appetite, not only because of swollen throat. In the mouth, the skin begins to die off, solid films are formed, they disappear and become sores. Ulcers appear on the tongue, lips, nose.
Owing to stomatitis, saliva flows more and more actively, it comes out with impurities of dead tissues, rot. From here and terribly unpleasant smell from a mouth.
If at first the diseased individual had no stool, then diarrhea begins. The feces come out painfully, with blood clots. Urination is given to the cow with difficulty and severe pain. There may also be blood in the urine. The results of the analysis can be seen the presence of protein.
Manifestation fever and on the skin. A rash is found everywhere with falling hair. The rash quickly turns into boils. Often they burst and a new infection gets into open wounds. Ulcers are even visible on the vaginal mucosa. Therefore, in severe disease, abortion of a cow often occurs.
The section describes all the likely symptoms at this stage of the disease. But if a cow's body is strong, they may not come at once. For example, inflammation on the skin is visible in most cases with mild disease. Then there will be a slight fever, lacrimation and discharge of mucus from the nose and mouth. As a rule, it concerns younger cows.
Depending on the degree of flow, experts note either at the same time organ damage, or partially. From here, depending on the area of infection and the manifestation of ZKG, forms are distinguished:
Body temperature on the second day is very high. But she soon drops to thirty-nine or forty degrees. When the mark decreases further, it is an indicator of a significant deterioration and death.
In this case, talking about the acute course of fever. Death occurs in a maximum of twelve days. The cow is literally melting before our eyes: it is rapidly losing weight, lying in a prone position and dying of hunger. In rare cases, the peak can be passed and the animal comes to food. But this is only temporary relief. There are more difficulties ahead.
Unfortunately, the full recovery is rarely talked about. Usually, states of deterioration are replaced by slight improvements, and there is hope in the breeder. But then the cow weakens again and dies.
If, however, a miracle happened, then most often the symptoms of catarrhal fever in a cow do not disappear without a trace:
- inflammation of the nasal mucosa becomes chronic,
- persistent sinusitis
- the amount of milk is reduced,
- heart failure,
- one or even both eyes may stop seeing.
In severe cases, when treatment is useless or does not occur in a timely manner, the disease affects literally all departments and organs of cattle.
As for the head, the mucous membranes are covered with pus with particles of dead tissue. This includes larynx and trachea. Signs of bronchopneumonia are noticeable in the lungs, sometimes fluid accumulates in them with blood particles.
In the eyes of the conjunctiva inflamed, the cornea, marked hemorrhage. In the mouth, the mucous membrane is friable, the tissue is dead, the tongue is covered with scales and films. A similar situation is observed in the intestines, it becomes more dense, covered with ulcers. It contains dark liquid with blood elements.
These symptoms allow you to establish the diagnosis. Absolutely all mucous membranes are inflamed, the fabric hardened and collapsed on them. The temperature is high, trembling in the body or in some places, dull eyes and general intoxication.
These are indicators of malignant catarrhal fever, if it was possible to exclude other infections.
If the eyes are not changed and serious changes do not occur in the oral cavity, the breeders accept the remaining symptoms as an upset stomach or other infectious diseases. For example, the plague of cattle is similar in symptoms to the CCH. The first also strikes:
But it is the hemorrhage in the front of the eyes or their clouding that produces fever. Another important is the defeat of the respiratory tract and convulsions. In addition, the plague will spread rapidly throughout the herd. But catarrhal fever from each other are not infected.
Some intersections on the signs are in the GC and with foot and mouth disease. However, the latter is characterized by the presence of bubbles in the mouth and in the hoof gap.
According to the listed parameters, the conclusions will be disappointing. The question of the recovery of a sick cow is extremely rare. Heavy form almost a hundred percent ends in death. Special attention should be paid to temperature fluctuations, in particular, on the third day after the start. Most likely in this case there will be an irreversible damage to the lungs and intestines.
When the first symptoms of catarrhal fever occur in a cow, it is necessary to act promptly. The disease is a serious infectious disease with damage to vital organs.
But not always it proceeds rapidly, so you can have time to take a number of measures:
- the sick animal must live separately from the herd in a room without a bright light,
- if the appetite is not lost, give a light juicy, easily digestible food,
- constantly water
- cool compresses between the horns are used to lower the temperature,
- intramuscularly prick caffeine twice a day,
- treatment of mucous membranes with a solution of potassium permanganate, chamomile decoction and other antiseptics,
- ulcers smeared after treatment with iodine-glycerin,
- eyes are washed with boric acid solution,
- prescribe antibiotics from the group of macrolides and cephalosporins,
- in diarrhea, dehydration occurs, up to six liters of saline sodium chloride is administered to the cow,
- severe damage to the eyes is treated by subcutaneous administration to the lower eyelid area of horse serum,
- intravenous calcium chloride solution helps prevent brain swelling.
Milk obtained from the herd, where even one individual was found to have catarrhal fever, is not worth drinking in its raw form. You can use only boiled product. Allowed to use products eight weeks after the death of animals or recovery. During the period of quarantine, you can not take out cows and graze them next to sheep and goats.
It is very important to conduct a daily inspection in the herd. For this temperature is measured. If any signs of the CCH appear, the cow will be isolated just in case. To establish the diagnosis accurately, you can take tests.
In the premises where they hold the sick animal, disinfection should be carried out. Treat all solutions of caustic soda, bleach and other drugs. Clean up in such pens need twice a day.
If the treatment does not help, then the cow will be sent to the slaughter in a specially designated place.
Although meat from infected livestock can be consumed, you need to be careful. All affected organs, especially the head, tongue and so on, should be destroyed. The resulting meat must be boiled and applied for the manufacture of canned products.
Quarantine can be removed from the farm only two months after the cows recover. Before this, the final disinfection of the premises is carried out. To prevent infection, you need to take the following measures:
- graze small and cattle separately,
- regularly clean the pens, get rid of old flooring,
- disinfect the premises at least twice a month,
- improve the immunity of animals with vitamins, high-quality nutrition, walking.
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