Brucella is a group of bacteria that can cause contagious infection in dogs, humans, and other animals. Several species of the bacteria can be picked up from contact with farm animals, but Brucella canis is the most common strain that causes brucellosis in dogs. B. canis is passed very easily from dog to dog and typically causes an epidemic with animals kenneled in close quarters. It is usually found in intact animals, so dogs kept for breeding purposes are more at risk. B. canis causes venereal infection in both sexes. In females, the most noticeable symptom is miscarriage late in the pregnancy (about 45-55 days). If the pregnancy is carried to term, the puppies may also be stillborn. Female dogs that are not pregnant when they are infected often have a uterine infection with persistent vaginal discharge and are unable to conceive. In male dogs, brucellosis causes inflammation in the sexual organs and infertility. Symptoms may be less noticeable, but some dogs have an enlarged scrotum or scrotal dermatitis. General inflammation of the lymph nodes is a common problem; arthritis and inflammation in other parts of the body can also be a complication, but this is rare. B. canis is passed through ingestion or sexual exposure to infected fluids. Aborted pups and fluids all carry the bacteria, so miscarriage in a confined setting with close proximity to other dogs can be a problem. Urine and saliva are also infectious, but to a lesser degree. No vaccine is available for brucellosis, and treatment is only partially effective, so control is based on regular testing and isolation of infected dogs. Spaying or neutering can reduce the risk of passing the bacteria to other animals, as can antibiotic treatment, but it is usually not possible to eliminate the bacteria.

Brucella bacteria can cause infection in dogs, humans, and livestock animals. The species specific to dogs, Brucella canis, is less dangerous to humans than those found in farm animals, but in dogs it can cause miscarriage and serious venereal disease. Treatment can reduce the risk of spreading the disease, but it does not cure infected animals.

These symptoms could indicate a brucellosis infection, especially in intact animals. Any sick dog should be isolated immediately to avoid spreading the disease.

Both sexes may develop inflamed lymph nodes (lymphadenitis). Other complications include vertebral inflammation (diskospondylitis), eye infection (uveitis), kidney infection (glomerulonephritis) and arthritis.

The following species of Brucella bacteria could cause an infection in dogs.

Brucella canis – the most common species specific to dogs

Brucella abortus – from cattle

Brucella suis – from pigs

Brucella melitensis – from goats

B. canis causes the most serious illness in dogs, but the other three species are also transmissible and can cause more severe disease in humans.

Brucella infection is associated with any of the following conditions.

Spontaneous abortion with little warning is often a reason to suspect brucellosis in females, however the bacteria is definitively isolated through serological examination of infected fluids. This includes blood, vaginal discharge, semen, milk, and stillborn or aborted pups. A fluid sample will be sent to a lab, where various tests can definitively isolate B. canis bacteria. Since the disease spreads easily, it’s recommended that dogs at high risk, such as those living in a breeding kennel, be given regular blood tests even if they are not showing symptoms. The infection is detectable after eight to twelve weeks.

Long term intravenous antibiotic treatments, including streptomycin, gentamicin, and tetracycline,  have been somewhat successful at controlling Brucellosis, but entirely eliminating the bacteria can be very difficult. Once diagnosed, animals are usually considered infectious for life. Spaying or neutering the animal may help to reduce the risk of passing the disease to other dogs, or to humans. In extreme cases, dogs with brucellosis may need to be euthanized to prevent an epidemic.

A complete recovery from brucellosis in dogs is unlikely. Attempts have been made to develop a vaccine, but at present they remain unsuccessful. Prevention and regular testing are the most effective ways of managing the disease. Dogs should be tested before breeding or entry into a kennel. Kennels dogs kept in individual cages have a much lower rate of infection. Good hygiene, especially in relation to pregnant females and miscarriage, can help to reduce the chance of spreading the disease. All infected animals should be isolated immediately.

B. canis is a zoonotic organism. Cases of it being spread to humans are relatively rare, but they remain a possibility especially for people with a compromised immune system. B. canis is a reportable disease in some states. Dogs infected with a different strain of Brucella should be handled with even more caution. Regular cleaning, wearing gloves around infected animals, and avoiding contact whenever possible can reduce the risk of infection in humans as well as other dogs.