Canine Brucellosis: Understanding the Disease

Key Diagnostic Points

1. The primary sources of infection are sick dogs and carriers, with pregnant females being the most dangerous due to the large amounts of Brucella bacteria shed during delivery and abortion. These bacteria are present in the placenta, amniotic fluid, and胎衣, as well as in vaginal discharge and milk postabortion. The main route of transmission is through the digestive system, with the oral, conjunctival, and vaginal mucous membranes being the most common entry points. The mucous membranes of the digestive tract and skin wounds can also allow the bacteria to enter the body, causing infection. Additionally, due to the high concentration of the bacteria in the semen of infected males, the disease can be transmitted during mating.

2. The disease is often asymptomatic, characterized by lymphadenopathy without fever. Abortions caused by Brucella can occur between the 40th and 50th day of pregnancy. Postabortion, the dog may experience a longterm discharge of serous fluid from the vagina, with the discharge being pale brown or graygreen in color. Dogs may exhibit lymphadenopathy, splenitis, and chronic bacteremia, but can still become pregnant normally during the next estrus cycle. Males may suffer from epididymitis, prostatitis, testicular atrophy, lymphadenopathy, and bacteremia, which can lead to infertility in both sexes. Affected dogs may also develop arthritis, tenosynovitis, and occasionally lameness, in addition to reproductive system symptoms.

3. Dogs with asymptomatic infections typically show no visible or pathological changes, or only lymphadenitis. In dogs with more pronounced clinical symptoms, postmortem examination may reveal changes such as arthritis, tenosynovitis, osteomyelitis, mastitis, orchitis, and lymphadenitis.

4. Suspect the disease in pregnant dogs that experience abortions or infertility. Diagnosis should be made by combining epidemiological data, clinical symptoms, bacteriological tests, and serological tests. Bacteriological tests can involve taking samples from aborted placentas, fetal stomach contents, or affected liver, spleen, and lymph nodes, preparing smears, and using differential staining methods to identify red bacteria for confirmation. Serological tests include tube agglutination tests and complement fixation reactions.

Treatment Methods

Antibiotic therapy can be employed. Commonly used antibiotics include oxytetracycline (20 mg per kilogram of body weight, three times daily, orally), gentamicin sulfate (1240 mg per kilogram of body weight, three times daily, orally), and amikacin sulfate (510 mg per kilogram of body weight, twice daily, intramuscularly). The use of vitamin C and vitamin B1 can enhance the effectiveness of treatment.

Preventive Measures

1. Regular serological testing of dog populations, ideally twice a year, with negative results being suitable for breeding.

2. Attempt to breed dogs inhouse and quarantine any new dogs purchased.

3. Test stud dogs for the disease before breeding and only allow healthy ones to mate.

4. Ensure proper disinfection of dog housing environments.

5. Isolate or cull infected dogs immediately.

Brucella infections in dogs are often asymptomatic, making them potential sources of infection for humans. Transmission routes include ingestion, contact, and inhalation, with the highest risk during the dog's abortion and delivery periods. Therefore, veterinary staff and laboratory workers who come into close contact with dogs should take appropriate personal protective measures.