Canine brucellosis is a bacterial infection caused by Brucella canis. It primarily spreads through breeding and reproductive fluids and can cause infertility, late-term abortion, and chronic disease. Per Hensel et al., 2018, Vet Record, the disease is endemic in much of the world and has emerged as a concern in commercial breeding kennels and adopted strays. It can also infect humans, making owner awareness important.
Last reviewed: May 2026
What Brucellosis Is
Brucellosis in dogs is caused mainly by Brucella canis, a slow-growing bacterium that lives inside cells of the lymphatic and reproductive systems. It spreads primarily through direct contact with reproductive fluids — semen, vaginal discharge during heat, aborted material, urine — and through breeding. Indirect transmission through shared toys, food bowls, or surfaces is possible in kenneled environments. Greene's Infectious Diseases of the Dog and Cat (4th edition, 2012) describes the bacterium as challenging to clear because it hides intracellularly and creates chronic, often subclinical, infections.
Signs in Dogs
Many infected dogs show no obvious signs for months to years. When signs appear, they vary by sex and stage of disease. In intact females: infertility, late-term abortion (typically 45 to 55 days of gestation), stillborn or weak puppies, and prolonged vaginal discharge after abortion. In intact males: scrotal swelling, painful or atrophied testicles, infertility, and inflammation of the prostate. In both sexes: swollen lymph nodes, lethargy, weight loss, back pain (from spinal disc infection — diskospondylitis), eye inflammation (uveitis), and occasionally neurologic signs. Spayed and neutered dogs without prior breeding history may carry the infection without producing reproductive signs.
How It Spreads to People
Brucellosis is a zoonotic disease — it can infect people. Human cases are uncommon but documented, especially in breeders, kennel staff, veterinarians, and lab workers. Symptoms in humans include intermittent fever, fatigue, joint pain, headache, and night sweats — often misdiagnosed for months. Children, pregnant women, and immunocompromised people are at higher risk for severe disease. The CDC recommends that owners of B. canis-positive dogs discuss exposure with their physician, and that immunocompromised individuals avoid handling infected dogs or reproductive material.
How Vets Diagnose It
Testing usually starts with an RSAT (rapid slide agglutination test) — quick and inexpensive but with a high false-positive rate. Positive RSATs are confirmed with more specific tests: AGID (agar gel immunodiffusion), tube agglutination test (TAT), or PCR on blood or tissue. Blood culture remains the gold standard but is hard because the bacterium is slow-growing and requires biosafety precautions. The AAHA Canine Vaccination Guidelines, 2022 note that no vaccine for B. canis is currently licensed, so testing and culling positive breeding animals is the main control strategy.
Treatment
There is no reliable cure. Long-course combination antibiotics (typically a tetracycline such as doxycycline combined with an aminoglycoside or fluoroquinolone, given for 4 to 12 weeks or longer) can reduce bacterial load and improve clinical signs, but the bacterium often persists intracellularly and the dog remains infected for life. Spay or neuter is strongly recommended in all positive dogs to reduce shedding. Some shelters and breeders euthanize positive dogs because of zoonotic and herd-disease risk. Decisions about lifelong management should be made with a veterinarian and, if zoonotic concern exists, a physician.
When to See a Vet
Call your vet today if:
- An unspayed female dog with late-term abortion or stillbirth
- An intact male with scrotal or testicular swelling or change
- Persistent vaginal or preputial discharge
- A breeding dog with unexplained infertility
- A newly adopted dog from a high-volume breeder or stray source — request screening
Go to the ER immediately if:
- Severe abdominal pain in a pregnant dog with vaginal discharge
- Acute spinal pain, paralysis, or inability to walk (suggests diskospondylitis)
- Severe eye redness with vision loss
- Collapse, weakness, or labored breathing
- An immediate post-adoption dog with concerning systemic signs
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Frequently Asked Questions
How much does brucellosis testing cost?
A screening RSAT is typically $30 to $80 at a general practice and is often included in breeding pre-screen panels. Confirmatory testing (AGID, TAT, or PCR) ranges from $80 to $250. A full breeding-soundness panel including brucellosis is $200 to $500. Treatment courses with multiple antibiotics for 8 to 12 weeks add $200 to $600, plus recheck testing.
Should I test my newly adopted dog?
Testing is reasonable if your dog comes from a high-volume breeder, an imported source, or an area where brucellosis is known to circulate. Most healthy adopted dogs from rescues or low-risk sources do not need routine screening. Discuss your specific situation with your vet — risk varies by region and history.
Can my family catch brucellosis from our dog?
Risk to a household with a positive dog is low but not zero. Most human cases occur in breeders, kennel staff, and veterinary workers with heavy reproductive-fluid exposure. Spaying or neutering a positive dog dramatically reduces shedding. Always wash hands after handling discharge or reproductive material; pregnant women and immunocompromised people should consult their physician.
Can a brucellosis-positive dog live with other dogs?
Yes, if both are spayed or neutered and not in heat or used for breeding. Routine household contact (sharing space, toys, food bowls) carries a very low transmission risk once reproductive shedding is reduced. Multi-dog breeding kennels are the highest-risk situation.
Is there a vaccine?
No licensed vaccine for B. canis exists in the United States or most of the world. Prevention relies on pre-breeding testing of both parents, quarantine and testing of imported dogs, and spaying or neutering positive animals.
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