Weather changes trigger acute dehydration and death in rabbits, requiring vigilance

In August 2007, an acute intestinal infectious disease characterized by severe diarrhea, dehydration and rapid death occurred in the breeding rabbit flock of a rex rabbit farm. The incidence rate was about 60%, and the mortality rate reached 40%. Based on epidemiology, clinical symptoms and pathological changes, combined with laboratory testing, it was finally diagnosed as Tyzzer's disease in rex rabbits. The relevant situation is reported as follows.

I. Onset process

A @#@248@#@ farm raised 1000 rex rabbits, of which more than 200 were breeding rabbits. In early August, after 5 consecutive days of local rain and with the temperature exceeding 30 degrees for a consecutive week, individual rabbits in the flock showed symptoms of diarrhea. At that time, the diseased rabbits were dissected and Clostridium welchii was suspected. Ciprofloxacin was mixed into the feed, but the effect was not obvious, and the disease developed rapidly. Deaths began to appear 2 days later. Later, laboratory testing confirmed infection with Tyzzer's disease. The large flock was quickly treated with oxytetracycline mixed into the feed, diseased rabbits were isolated, and butylamine was injected intramuscularly and penicillin was injected intramuscularly for treatment.

II. Clinical symptoms

This disease is mainly characterized by severe diarrhea, mostly brown pasty to watery. The hind limbs are often stained with feces. Diseased rabbits are depressed, refuse to eat and rapidly become dehydrated, often dying within 12-48 hours after symptoms appear. A small number of diseased rabbits that survive the acute phase show poor appetite and emaciation.

III. Pathological changes

Dead rabbits were dehydrated and emaciated, with feces contaminating the hind limbs. The serosa and mucosa of the terminal ileum, cecum and colon showed diffuse congestion and hemorrhage, and the intestinal wall was severely edematous and thickened. The cecum and colon were filled with gas and brown pasty contents. The mesenteric lymph nodes were edematous. The spleen was severely atrophied. The liver was enlarged, with many grayish-white streak-like necrotic areas. In a small number of dead rabbits, grayish-white striped spots or patchy necrotic areas could be seen on the myocardium. In individual diseased rabbits that survived the acute phase, the intestinal wall was thickened due to severe necrosis and fibrosis, and the intestinal lumen became narrowed.

IV. Diagnosis

A preliminary diagnosis can be made based on clinical symptoms and necropsy changes. Smears made from the tissue of the necrotic areas of the liver and the mucosa of the intestinal lesions of dead rabbits, stained with Giemsa or stained by the silver impregnation method and examined under a microscope, can confirm the presence of Bacillus piliformis in the cytoplasm, allowing a definitive diagnosis.

V. Prevention and control measures

Diseased rabbits were isolated in a timely manner, disinfection was strengthened, feeding management was strengthened, and stress was reduced. For unaffected rabbit flocks, oxytetracycline was mixed into the feed for five consecutive days, and electrolytic multivitamins or glucose were used in drinking water to increase the rabbits' own resistance. Butylamine was injected intramuscularly at 60,000 per rabbit, once a day, for three consecutive days. Mild cases were quickly brought under control, while those with acute onset died before treatment could be given. After two weeks, no new cases appeared, and the large flock was basically brought under control.

VI. Summary

This disease is mainly infected through the digestive tract. The feces of diseased rabbits, as well as contaminated feed, drinking water and bedding straw, are all major sources of infection, and healthy rabbits can become infected after contact. The pathogen invades the mucosal epithelium of the small intestine, cecum and colon. At first it proliferates slowly, causing very little tissue damage, and mostly presents as a latent infection. Once various stress factors that reduce the body's resistance are present, it can be induced, and the pathogen will take the opportunity to proliferate rapidly, causing deep tissue necrosis of the intestinal mucosa, leading to systemic infection and severe damage to tissues and organs.

According to investigation and analysis, this outbreak was very likely already infected with this disease in a latent state. Due to sudden climate changes and moldy feed and other stress factors, the outbreak of this disease was induced.

Through the treatment of this disease, it was found that the therapeutic effect of butylamine combined with oxytetracycline and electrolytic multivitamins was obvious, for reference by peers.