Characteristics of Canine Brucellosis and Detailed Explanation of Prevention and Treatment Methods

Brucellosis is a zoonotic disease caused by Brucella bacteria that can be transmitted between humans and animals. The most common cases involve infection in cattle, sheep and pigs; humans and other animals become infected and develop the disease after consuming infected animals and their products, and carrier humans and animals are the main sources of infection. After dogs are infected with brucellosis, they mostly show subclinical symptoms, and only a small number of infected dogs develop clinical symptoms. The main characteristic of this disease is inflammation of the reproductive organs and fetal membranes.

The pathogen Brucella is a Gram-negative bacterium, appearing spherical, coccobacillary or short rod-shaped, with a size of 0.5-0.7 micrometers x 0.6-1.5 micrometers, non-motile, and does not produce spores or capsules. It is divided into 6 species and 19 biovars, namely: Brucella melitensis, Brucella abortus, Brucella suis, Brucella ovis, Brucella neotomae, and Brucella canis. Dogs are susceptible to all species of Brucella.

Epidemic characteristics The main transmission route of this disease is through the digestive tract, with infection occurring through ingestion of food, feed and water contaminated by the pathogen. The oral mucosa, conjunctiva, vaginal mucosa and broken skin are all entry points for the pathogen. Testing has found that the positive rate of canine brucellosis in China is 1.68%-13.4%. The vaginal secretions, dead fetuses and placental tissues of aborting female dogs all carry the bacteria. The semen and urine of male dogs with brucellosis carry the bacteria and can transmit the infection through mating.

Symptoms Canine Brucella infection is generally mostly subclinical or manifests only as lymphadenitis, and systemic clinical symptoms may also appear after an incubation period of 2 weeks or half a year. Some affected female dogs show abortion symptoms at 40-50 days of pregnancy, but their body temperature is not elevated. The labia and vaginal mucosa become red and swollen, and light brown or grayish-green discharge flows from the vagina. Aborted fetuses show subcutaneous edema, congestion, hemorrhage and autolysis of some tissues. Some infected female dogs experience embryonic death and resorption in early pregnancy (10-20 days after mating) without showing abortion symptoms, along with inflammation of the endometrium, and clinically present with repeated failure to conceive. Infected male dogs develop symptoms such as orchitis, epididymitis, prostatitis and balanoposthitis. In addition to reproductive organ diseases, affected dogs may also develop symptoms such as arthritis, tenosynovitis and lameness.

Diagnosis Based on reproductive disorder symptoms in female dogs and inflammation of the genital organs in male dogs, blood is collected and serum is separated for complement fixation test or tube agglutination test for further confirmation.

Treatment Because Brucella parasitizes inside cells, antibiotics have difficulty taking effect against it, making treatment difficult and prone to recurrence. In the early stage, minocycline can be administered (25 mg/kg, twice a day, for more than 3 weeks), along with intramuscular injection of dihydrostreptomycin (10 mg/kg, twice a day, for 1 week) or gentamicin. During medication, it is best to choose drugs in accordance with the results of drug sensitivity testing.

Prevention

1. Breeding dogs should be tested by blood collection on a regular basis, and dogs found to carry Brucella should be culled and subjected to harmless disposal.

2. Stud male dogs should undergo serological testing before mating to determine whether they are healthy.

3. Dog kennels should be disinfected frequently, and aborted fetuses and contaminated materials should be subjected to harmless disposal.

4. Individuals keeping dogs should have their dogs undergo regular health examinations. If a beloved dog is found to be ill, it should be actively treated or euthanized and subjected to harmless disposal, and contact with sick dogs should be reduced to avoid infection with this disease.