Malignant catarrhal fever, or fever, of cattle is a non-contagious sporadic infection. It manifests itself in cows as lobar inflammation of the serous and mucous membranes of the gastrointestinal tract, damage to the respiratory system, lymphadenitis, persistently high temperature, and nervous disorders. Farm animals of all ages, breeds, wild and domesticated artiodactyls are susceptible to infection.
History of appearance
Malignant catarrhal fever (MCF, bovine malignant catarrh) was first described by Anker in 1832. A zoologist named the infection “bovine typhus.” In the Russian Federation, the disease was established in 1873 by I. I. Ravich. The infectious nature of MCH was identified by Metam in 1923, and the causative agent of bluetongue was described in his scientific works by Piercy in 1953.
Malignant catarrhal fever is registered everywhere in the world, in all regions of our country. The infection manifests itself seasonally, in sporadic outbreaks, and local enzootics in individual livestock complexes and farms.
Causes of the disease
Malignant bovine catarrh is caused by a lymphotropic filtering DNA virus of the Herpesviridae family. Having penetrated the body, the pathogen is transported through the bloodstream to brain cells, lymph nodes, and parenchymal organs. Affects mucous, serous membranes and tissues.
Important! Under favorable conditions, the MCH virus remains virulent in the external environment for 32-38 days.
The source of infection is sick individuals, latent virus carriers. The main method of transmission of MCH is contact, airborne droplets. Causes of malignant catarrhal fever in cattle:
- grazing cattle with other artiodactyls;
- unfavorable conditions of detention;
- keeping young animals with adults;
- unbalanced poor diet;
- feeding rotten, wet hay, rotten feed;
- low body resistance, reduced immunity;
- hypo-, avitaminosis;
- prolonged hypothermia of the body;
- chronic respiratory infections, diseases of the respiratory system in cows.
Infected pastures, premises contaminated with the pathogen, feed, bedding, and equipment are also the main sources of infection of cows with bluetongue.Intrauterine (transplacental) infection of fetuses with MCH is possible.
Signs and consequences
In sick cows, CCG in the early stages is manifested by difficulty swallowing, shortness of breath, coughing attacks, and a sharp increase in temperature to 41.5-42 degrees. Fever and chills are stable. The cattle's appetite worsens and their behavior changes. The prodromal period is characterized by nervous disorders (impaired coordination, convulsions, paresis).
Manifestations and symptoms of malignant catarrhal fever in cattle:
- persistently high temperature, fever, chills;
- loss of appetite, refusal to feed;
- nausea, vomiting;
- disruption of digestive processes;
- enlarged, painful lymph nodes;
- lacrimation, mucous, purulent discharge from the eyes;
- anemia (pallor) of the mucous membranes, swelling, sticking of the eyelids;
- photophobia, keratitis;
- weak reaction to external stimuli;
- short-term loss of consciousness;
- muscle spasms, cramps, paresis;
- papular-vesicular rash on the neck, abdomen, udder, genitals;
- peripheral edema, tissue infiltration of the lymphocytic type;
- rashes, dry crusts on the nasal mucosa;
- unstable stool, foul-smelling diarrhea;
- difficulty urinating;
- cough, shortness of breath, bronchitis;
- weight loss.
Important! The incubation period for MCH in cattle lasts from several days to three to five months. The disease occurs acutely, hyperacutely, chronically. There are known cases of atypical forms of infection. High mortality is noted in hyperacute, acute course of MCH.
In lactating cows with malignant catarrhal fever, milk production is completely absent or milk yield is reduced. Fibrin flakes and bloody inclusions are noticeable in the milk. In infected individuals, breathing is shallow and labored. Foci of necrosis, white dry crusts, and brown scabs appear on the nasal mirror.
Animals experience extreme thirst. The chewing stops. In cows, the secretory function of the gastrointestinal tract is disrupted. Profuse bloody diarrhea is replaced by short-term constipation. Fibrin flakes and undigested food are present in the feces. The abdomen is enlarged due to increased gas formation and impaired intestinal motility.
On palpation, pain and enlargement of regional lymph nodes are noted. Foci of inflammation, ulcers, and erosive lesions are noticeable on the mucous membrane of the nasal and oral cavities. If treatment is not started in time, catarrhal fever provokes intestinal atony, severe colic, intestinal spasms, and paralysis of the respiratory system.
Diagnostic measures
When making a diagnosis of malignant catarrh, the epizootological situation in the region is taken into account, anamnesis data, and the results of clinical studies are taken into account. The cow's mucus from the mouth and nasal cavity, discharge from the eyes, feces, urine, and blood are taken for analysis. The most accurate picture of the situation with this disease in the regions and livestock farms is obtained from the results of serological tests and pathological data.
Additionally, differential diagnosis is prescribed due to the similarity of the symptoms of bluetongue with adenovirus, rotavirus infection, rhinitis, purulent conjunctivitis, parainfluenza, listeriosis, rabies, and leptospirosis.
Treatment of malignant catarrhal fever
Traditional veterinary medicine resorts to complex therapy when diagnosing CCG in cows and buffaloes.
In the treatment of catarrhal fever the following is used:
- complex antibiotics;
- anti-inflammatory, antipyretic;
- cardiac glycosides;
- sulfonamides;
- solutions that envelop the gastrointestinal tract;
- cold compresses;
- autohemotherapy for prolonged forms of infection.
To normalize the general condition, the functioning of internal organs, and digestive processes, symptomatic medications and probiotics are indicated. The oral cavity is irrigated with potassium permanganate (diluted in a ratio of 1/1000), after which the affected areas are lubricated with Lugol's solution. Therapy is supplemented with vitamin and mineral supplements, restorative and tonic preparations.
Important! During treatment of patients with malignant catarrhal fever, cows are isolated from the general herd and kept in dark, well-ventilated rooms. When feeding, use juicy, soft food. Drink acidified water.
They thoroughly disinfect the premises, adjust the diet, and improve the living conditions of farm animals.
Is there a quarantine?
When malignant bluetongue is diagnosed, quarantine is introduced in farms. In the event of numerous outbreaks of infection in complexes, the region is unfavorable. Strict quarantine measures are being introduced aimed at preventing the spread of bluetongue in cows.
Important! In individual agricultural lands, on farms, and complexes, malignant bovine catarrh can manifest itself periodically, in seasonal outbreaks for 4-10 years in a row.
The import and export of livestock for production purposes, selection, breeding, and the sale of meat and dairy products from cows is prohibited until restrictions are completely lifted from regions unfavorable for this infection, livestock farms, farm complexes, and households. Terminally ill cows are sent for slaughter with subsequent disposal of the corpses.
Preventive actions
To prevent outbreaks of bluetongue in cows, a number of preventive measures are taken.
Preventive actions:
- separate keeping of young animals with adults, separate grazing of cattle with sheep, goats;
- compliance with sanitary and hygienic standards on farms;
- systematic disinfection of barns;
- high-quality balanced diet;
- separate keeping of recovered animals from healthy animals.
If cattle are suspected of being infected with bluetongue, a daily clinical examination of the entire livestock is carried out.
