Brucella canis is a bacterial infection that primarily affects dogs. This contagious pathogen causes canine brucellosis, a disease present globally that can lead to significant reproductive issues in infected canines. It is particularly concerning in breeding environments due to its highly contagious nature among dogs.
How Dogs Contract Brucella Canis
Dogs primarily contract Brucella canis through direct contact with infected bodily fluids. Sexual contact is a significant route of transmission, as dogs are exposed to bacteria in vaginal fluids, semen, or pro-estral blood during mating. This makes breeding environments high-risk settings for infection spread.
Exposure to reproductive fluids from an infected dog, such as during whelping or abortion, also poses a substantial risk. B. canis bacteria are shed in large numbers in vaginal discharges and semen. After an infected female dog aborts, she can continue to shed the bacteria in fluids for approximately 4-6 weeks.
Transmission can also occur through contact with other bodily fluids like urine, saliva, or nasal secretions. Puppies can acquire the infection in utero or through their mother’s milk. The bacteria can enter the body through mucous membranes, such as the mouth, eyes, or vagina, or through abraded skin.
Recognizing Signs in Dogs
Dogs infected with Brucella canis may exhibit a range of clinical signs, though some can be subtle or absent, making diagnosis challenging. In female dogs, reproductive issues are common, including infertility, late-term abortions, and the birth of stillborn or weak puppies that may die shortly after birth. A persistent vaginal discharge may also be observed.
Male dogs often develop epididymitis, an inflammation of the epididymis, which can lead to an enlarged or painful testicle and potentially a skin rash on the scrotum. Over time, the testicles may shrink. Infertility is also a common outcome for infected males.
Other signs can occur beyond reproductive problems. Dogs might experience enlarged lymph nodes, particularly in the neck, armpit, or groin. B. canis can also infect other organs, leading to signs such as lameness, back pain, or eye inflammation.
Diagnosis and Treatment Approaches
Diagnosing Brucella canis can be complex, often requiring a combination of tests due to the potential for false negatives or positives with single methods. Blood tests are frequently used to detect antibodies, indicating exposure to the bacteria. These include serological tests that identify antibodies to B. canis. However, these antibody tests may produce false negatives early in the infection or false positives due to reactions with other bacteria.
A more definitive diagnosis often involves bacterial culture, where samples of blood, urine, or reproductive fluids are grown in a laboratory to isolate the bacteria. Culture can be time-consuming and may yield false negatives if the bacteria are not actively shed or if the dog has recently received antibiotics. Polymerase Chain Reaction (PCR) tests, which detect bacterial DNA, are also employed and can be highly sensitive, sometimes detecting the bacteria even when culture is negative.
Treatment for Brucella canis involves a long-term course of multiple antibiotics, often for at least 4-12 weeks, though complete eradication of the infection is difficult. Dogs may remain carriers and intermittently shed the bacteria for years, even after extensive antibiotic therapy. Surgical sterilization, such as spaying or neutering, is often recommended for infected animals to reduce bacterial shedding and minimize transmission risk, though it does not cure the infection entirely.
Risk to Humans and Prevention
Brucella canis is a zoonotic disease, meaning it can transmit from dogs to humans, though human infections are rare. Transmission to humans usually occurs through direct contact with infected reproductive fluids or tissues, such as those associated with breeding, whelping, or aborted materials. Veterinarians, breeders, and laboratory workers handling infected samples are at a higher risk of exposure.
Human symptoms, when they occur, are often non-specific and can resemble the flu, including fever, headaches, muscle aches, fatigue, and swollen lymph nodes. In more severe cases, joints, bones, or heart valves may be affected. People with compromised immune systems, young children, and pregnant women are at a higher risk of developing more severe illness if infected.
Prevention strategies focus on minimizing exposure and controlling the spread within dog populations. Testing breeding dogs for Brucella canis before mating is a primary preventive measure. Isolating newly acquired dogs, especially those from high-risk areas, and performing multiple tests over several months can help prevent the infection’s introduction into a household or kennel. Practicing good hygiene, such as wearing gloves when handling reproductive fluids or tissues, and washing hands thoroughly after contact with dogs, is also recommended.