Brucellosis in Dogs: Everything Stud Owners Must Know

Brucellosis is the one disease every stud dog owner must understand — it is sexually transmitted, potentially fatal to breeding programs, and a human health risk

Brucella canis is a bacterial infection that should be at the top of every stud dog owner's awareness list. Unlike most canine diseases, brucellosis is sexually transmitted between dogs during breeding. It causes infertility, late-term abortions, stillbirths, and the destruction of testicles in affected males. And it is a zoonotic disease — meaning it can infect humans who handle infected dogs or their reproductive fluids.

Testing for brucellosis before every single breeding is not optional for a responsible stud dog operation. Here is everything you need to know.

What Is Brucella Canis?

Brucella canis is a gram-negative bacterium that preferentially infects reproductive tissues in dogs. It is one of four Brucella species that infect mammals — others affect cattle (B. abortus), pigs (B. suis), and goats/sheep (B. melitensis). All four can potentially infect humans; B. canis is considered less virulent in humans than the others but is still a genuine public health concern.

B. canis lives primarily in:

The concentration of bacteria in these fluids is highest during active infection and in the period immediately after abortion.

How Brucellosis Spreads Between Dogs

Direct Transmission

Sexual contact (breeding) is the primary route of transmission. An infected female transmits the bacteria to the stud during mating through vaginal secretions. An infected male transmits through semen.

Contact with aborted material is the most efficient transmission route — a female who aborts an infected litter sheds enormous numbers of bacteria in the fluids and tissue, and any dog or human who contacts this material without protection is at serious risk.

Contact with infected urine — Infected males may shed bacteria in urine for months. Dogs who share a yard with an infected male can be exposed.

Dog-to-dog contact at nose level — Sniffing the genital or anal area of an infected dog can transmit the bacteria.

In a Kennel Environment

Brucellosis in a multi-dog kennel is a catastrophic event. Once one dog is infected, all others who have been in close contact must be considered exposed. The entire breeding program may need to be halted pending testing of all animals.

What Brucellosis Does to Dogs

In Females

In Males

Systemic Signs (Less Common)

Brucellosis Testing: What Is Available and When to Test

The RSAT (Rapid Slide Agglutination Test)

The RSAT is the most commonly used screening test for B. canis in veterinary practice. Results are available the same day. It is inexpensive ($30-$60) and widely available.

Advantages: Fast, cheap, accessible. Limitations: Can produce false positives — approximately 50% of RSAT-positive results in low-prevalence populations are false positives. A positive RSAT must always be confirmed with a more specific test.

ME-RSAT (2-Mercaptoethanol RSAT)

A modified version of the RSAT with fewer false positives. Used as an intermediate confirmation step in some laboratories.

AGID (Agar Gel Immunodiffusion Test)

More specific than the RSAT. Reduces false positives significantly. Often used as the next step after a positive RSAT.

PCR Testing

Polymerase Chain Reaction (PCR) testing directly detects bacterial DNA in blood or reproductive secretions. It is highly specific and is increasingly used for confirmation. Available through several veterinary diagnostic laboratories.

Blood Culture

Growing B. canis bacteria from a blood sample is the gold standard for definitive diagnosis. Requires specialized laboratory conditions and takes several days to weeks. Used when clinical suspicion is high despite negative serological tests.

Testing Protocol

What a Confirmed Positive Means: Hard Truths

A confirmed positive B. canis diagnosis is one of the most serious situations a breeder can face. Here is the honest reality:

There Is No Cure — Only Management

Antibiotics can suppress B. canis infection and reduce bacterial shedding, but they do not eliminate the bacteria from the body. Dogs treated with antibiotics may test negative on serology while still harboring bacteria in reproductive tissues. Relapse after antibiotic treatment is common.

Infected Dogs Should Not Be Bred

A dog with confirmed brucellosis should not be bred under any circumstances. Even with antibiotic treatment and a subsequent negative test result, the risk of transmission remains. Most reproductive veterinarians and infectious disease specialists recommend permanent removal from breeding for confirmed positive dogs.

Neutering Reduces Shedding

Neutering an infected male significantly reduces the primary sites of bacterial shedding (testicles, epididymis, prostate). It does not eliminate infection entirely but reduces transmission risk substantially. Neutering infected females similarly reduces vaginal shedding. Most specialists recommend neutering confirmed positive dogs.

Euthanasia Is Sometimes Recommended

In some situations — particularly multi-dog kennels where containment is difficult, or in cases with serious secondary complications — euthanasia may be recommended. This is a devastating recommendation, but brucellosis in a breeding facility can destroy an entire program and expose humans to a zoonotic pathogen.

Disclosure to Buyers

If a breeding occurred before a brucellosis diagnosis was made, all recent breeding partners and their owners must be notified immediately. The dam owner must test their female and any affected dogs.

Brucellosis as a Human Health Risk

B. canis can infect humans, though it is considered less virulent in humans than B. abortus or B. melitensis. Human infection with B. canis typically causes:

Highest risk individuals:

Protective measures:

Prevention: The Only Reliable Strategy

The only reliable way to prevent brucellosis in your breeding program is rigorous testing.

Test both dogs before every single breeding. Not every other breeding. Not once a year. Before every single breeding, both the stud and the dam should have a current (within 30 days) RSAT result.

Do not breed with untested dogs. If a dam owner cannot produce a current brucellosis test result, decline the appointment. If a stud owner cannot produce a current test, do not use the stud.

Know your dogs' contacts. Dogs who attend shows, training facilities, or dog parks have more exposure risk than dogs who live in isolation. Higher-contact dogs warrant more frequent testing.

Isolate new dogs. Any dog new to your kennel — whether purchased, returned from a co-own, or visiting — should be quarantined and tested before contact with your other breeding dogs.

Summary

Brucella canis is sexually transmitted, causes infertility and late-term abortions, and can infect humans who handle reproductive materials. There is no reliable cure — confirmed positive dogs should be removed from breeding permanently and neutered. Prevention is the only dependable strategy: test both the stud and the dam with an RSAT before every single breeding, require proof of testing from all breeding partners, and handle all reproductive materials with gloves. A stud dog owner who cannot show a current brucellosis test is not a stud dog owner you want to work with — and the same standard should be applied to every dam owner who contacts you.