Brucellosis in DogsLast updated: February 7, 2022 by Marty Greer, Doctor of Veterinary Medicine
People think of brucellosis as a cause of abortion, but it is mostly seen it as conception failure, stillborns, or weak puppies. There is no treatment for Brucella canis, and it can be contagious to humans, creating the need to eliminate it from our breeding population! Once introduced, eliminating brucellosis is difficult and costly. In many cases, finding Brucella positive dogs in a breeding facility means your local state veterinary authorities can close down your kennel for a minimum of 90 days, require testing all dogs in the facility, and can require all positive dogs to be euthanized. Testing any dogs you may add into your breeding kennel prior to introduction is necessary to prevent it.
What is Brucellosis in Dogs?Brucellosis is a tiny bacterium that causes reproductive disturbances and abortion. It is potentially contagious to humans, but this is rare. Brucellosis causes a recurrent fever in humans, a disease known as undulant fever.
Often females who fail to conceive are the first indication of brucellosis. If you see discharge from the vulva at 30 days, we rule out brucellosis.
The Brucella organism is spread primarily at breeding and with vaginal discharge. However, the Brucella organism is also found in semen, urine, aborted material and placenta. Chronically-infected males or females will shed when stressed, spreading the disease to other kennel mates. Stressed animals have intermittent bacteremia and shedding in all body fluids, even when not pregnant.
Dog Abortion and InfertilitySpontaneous abortion with Brucella canis occurs at 45 to 59 days pregnant. A vaginal discharge of highly-contagious gray-green fluid will last one to six weeks. This is a major source of spreading the disease in the kennel! Other signs of B. canis are conception failure, fetal death and subsequent birth of mummies and weak puppies. Puppies born to infected bitches are infected with this non-curable disease.
How it LivesBrucella bacteria lives inside cells of the urogenital track of females, making it difficult to detect. In males it resides in the prostate, epididymis or both. At times, few organisms are circulating in the blood with chronically-infected females, and this causes difficulty in diagnosis on blood tests.
The RSAT Card test has returned to the market. Although this Brucellosis test for dogs is highly sensitive, it is not highly specific. This means you would be unlikely to miss a positive dog on the test, unless you are testing early in the disease. However, because it is so sensitive, it often shows false positives - lack of specificity. Up to 10% of the tests that show a positive result are false positives. The kit includes a second step to improve sensitivity. If both tests in the kit are positive, additional testing at a reference lab is required.
Brucella CultureVaginal swabs and serum can be cultured for Brucella. Cultures will not give false positives because once you grow it, you have the disease. It can have false negatives from having no organisms being shed in the sample, but fewer than the card test. Although culture is considered the "gold standard", it can take up to three weeks for an accurate result so is not useful as a screening process.
Agur Gel Immune DilutionThis test is run in the lab by putting your samples and negative samples in wells and having them diffused through gel with antibodies to brucellosis. The antibodies bind to Brucella and under certain wavelengths of light, they will fluoresce. These are compared to the negative samples to be sure it is accurate. This test usually takes two weeks to get results and is very expensive to run. The Agar Gel Tests are run to confirm positive results as it is very accurate.
New Brucella PCR TestA new test run by Iowa State University and Kansas State University is the PCR, which detects DNA genetic material. PCR for brucellosis can pick up as little as 10 bacteria in the blood, making it accurate at levels not seen in other tests. This test eliminates the false positives and negatives that plagued tests in the past. The accuracy of PCR gives us more comfort with testing, plus it is fast. We can usually get turnaround the same week, although they tell you 10 to 14 days. This test is less expensive and more accurate than culture; eventually states will replace its requirement for culture with PCR.
Canine Brucellosis PreventionAny additions to your kennel should be tested with the PCR test and isolated for four weeks. Artificial insemination (AI) can also help prevent the risk of transferring the disease (see below).
Adult Dogs Brought InAn adult dog infected with Brucella canis is rarely ill. They will trigger a positive test, but there have been cases where dogs were put on Tetracycline or another antibiotic for three weeks to get them to test negative and then sold. Antibiotic will eliminate bacteria from blood (not in the cells) and cause positive dogs to test negative for a short time you purchase later they re-activate and infect your kennel. That is why we do not like adult dog purchases – too much risk and you never sell your best dog!
If you add adult dogs, test twice 60 days apart with PCR to be sure you did not get a negative on antibiotic. If they have been tested, confirm what test they used, get a copy for your files and never trust a test from the seller – do your own, as the risk is too high.
Puppies are far less risk but still a risk. When brought in, you should PCR test them to be sure they are clean. One PCR test and puppy from a known source may make us comfortable with the addition to the kennel.
Breeding OutBreeding females coming into the kennel should be brucellosis-negative on PCR within 30 days of the breeding and arrive with the test results printed out from a veterinary clinic or reference laboratory – otherwise, don't breed! It is always best to breed AI from your male with no contact with outside female to decrease risk. The risk has made many of us refuse breeding other people's females, but if you insist on testing negative for brucellosis and using AI, it can be done safely.
There is no treatment to eliminate Brucella canis, and elimination is difficult once it is introduced to your kennel. Dogs who are persistently positive for Brucellosis in most states will be mandatorily euthanized. The new PCR test for all new additions to your kennel will help you in maintaining a brucellosis-free kennel!
If you need help, call us at 800.786.4751.
Donald Bramlage, Doctor of Veterinary Medicine, Former Director of Veterinary Services at Revival Animal Health
Donald Bramlage, Doctor of Veterinary Medicine, practiced veterinary medicine for 30+ years and is known for his work in managing parvovirus. He received his Doctor of Veterinary Medicine from Kansas State University in 1985. He served as Revival's Director of Veterinary Services from 2011 until his retirement in 2019.
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