Diagnosis and Treatment Methods for Rabbit Pasteurellosis and Bordetellosis

From May to July 2002, a disease characterized by rhinitis and acute death occurred successively at a certain rabbit farm. Through laboratory bacteriological examination, it was diagnosed as rabbit pasteurellosis. The report is as follows:

1. Basic information. The rabbit farm is located at **Chabucha'er County Dairy Farm. Rabbit farming began in 2000@#@248@#@. Currently, California rabbits, Belgian rabbits and other breeds are raised, with a total of more than 1,000 young and adult rabbits. All are raised in cages. No vaccines were injected, and no major epidemic had occurred in the past two years. In late May 2002, after continuous heavy rain, disease was triggered by low temperature and dampness in the rabbit house. More than 10 young and adult rabbits died acutely, and most rabbits that later became ill showed a chronic course, with more than 80 dying gradually over time.

2. Clinical symptoms. Some rabbits that died acutely showed no clinical symptoms and suddenly fell dead. Those with a longer course died in 3-6 d. The body temperature of sick rabbits rose to about 40°C, and a serous-to-purulent discharge flowed from the nasal cavity. Breathing was rapid and difficult, sneezing often occurred, and diarrhea sometimes developed. Before death, body temperature dropped, and the rabbits died with limb convulsions. In chronic cases, the main symptom was rhinitis. Initially, a serous nasal discharge flowed out, which later turned into a mucous-to-purulent nasal discharge. The rabbits often scratched and rubbed the nose with their front paws, making the hair around the nostrils damp and fall out, and the skin of the upper lip and nostrils became red, swollen and inflamed. Because sick rabbits often scratch the nose, bacteria can be carried into the eyes, ears or subcutaneously, causing purulent conjunctivitis, otitis media and subcutaneous abscesses. In severe cases, difficulty breathing, frequent sneezing, coughing and sometimes diarrhea appeared. Several sick rabbits died in the rabbit farm every day.

3. Necropsy pathological changes. There was a large amount of mucous-to-purulent discharge in the nasal cavity, and the nasal mucosa was congested or hemorrhagic and edematous; the mucosa of the larynx and trachea was congested and hemorrhagic, with a large amount of red foam; the lungs were edematous, congested or hemorrhagic; in rabbits that died acutely, liver deformation and small necrotic spots could be seen; lymph nodes and spleen were enlarged and hemorrhagic; congestion and hemorrhage were sometimes visible in the intestinal mucosa; after necropsy, most female rabbits showed pyometra, some sick rabbits had subcutaneous abscesses, and a few male rabbits showed testicular enlargement or orchitis after necropsy.

4. Bacteriological diagnosis

4.1 Liver, spleen, lung, kidney, pyometra material and subcutaneous abscesses were collected from dead rabbits for necropsy as disease materials, smeared, stained with Gram stain and Wright's stain, and examined microscopically. Gram-negative bipolar-staining small bacilli were seen.

4.2 Isolation and culture: The above disease materials were inoculated onto blood agar medium with an inoculation loop under sterile operation and cultured at 37°C for 24 h. Grayish-white, moist, viscous colonies grew and did not hemolyze; smears, staining and microscopic examination of the colonies still showed large numbers of Gram-negative bipolar-staining small bacilli, with no contamination by miscellaneous bacteria.

4.3 Biochemical reactions: To distinguish Pasteurella from Bordetella, the following biochemical tests were performed: from colonies in which bipolar-staining small bacilli were detected, an inoculation needle was used under sterile operation to inoculate glucose, sucrose, lactose, raffinose and rhamnose biochemical reaction small test tubes, followed by culture at 37°C for 48 h. The results showed that glucose and sucrose produced acid and changed color (no gas was produced), while lactose, raffinose and rhamnose showed no change.

5. Prevention and control measures

5.1 All rabbits on the farm were examined one by one. Rabbits with runny nose, sneezing, damp nasal hair or other clinical symptoms were isolated and treated separately, without contact with healthy rabbits. Healthy rabbits were injected with rabbit plague-pasteurellosis combined vaccine.

5.2 Do a good job in disinfection of the rabbit farm. First thoroughly remove feces, bedding, leftover feed and other filth in the rabbit house. Disinfect the floor with 10%-20% lime milk. Disinfect rabbit cages and utensils with 5%-10% bleaching powder. Burn filth such as feces and bedding of sick rabbits, and bury part of it deeply.

5.3 Each sick rabbit was injected with antibacterial king (Bajunke) injection at a dose of 0.5 mg/kg body weight. Twice a day for 4 d.

5.4 For healthy rabbits, enrofloxacin was added to drinking water at a dose of 5 g/100 kg water for 5 d.

5.5 Strengthen feeding and management, provide complete-price feed according to standards, meet nutritional needs, and pay attention to routine environmental sanitation in the rabbit house. When conditions permit, regularly clean, wash and disinfect the rabbit house to avoid dampness in the rabbit house. When major weather changes occur, such as continuous heavy rain or a sudden drop in temperature, strengthen protection of the rabbit population and improve the immunity of the rabbit population.

After the above measures were taken, except for a few sick rabbits that died, most clinical symptoms disappeared, and no new cases occurred.

6. Summary

6.1 Based on the above clinical symptoms and bacteriological examination, the disease outbreak at the rabbit farm can be definitively diagnosed as rabbit pasteurellosis. The clinical symptoms of this disease are very similar to those of rabbit bronchiseptic bordetellosis. They are also very similar in bacterial morphology and cultural characteristics. However, Pasteurella can ferment glucose while Bordetella cannot. From the above bacterial biochemical reactions, it can be definitively diagnosed that the bacterium is Pasteurella rather than Bordetella.

6.2 Pasteurella is a conditional pathogenic bacterium. The occurrence of Pasteurella is greatly related to weather changes and feeding and management conditions. The author believes that the direct cause of this Pasteurella outbreak at the rabbit farm was continuous heavy rain in May, a drop in temperature, dampness in the rabbit house, and poor feeding and management. To prevent the occurrence of this disease, it is necessary to do a good job in keeping the rabbit house warm, rainproof and moisture-proof, and at the same time strengthen feeding and management.