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Brucellosis is a contagious disease caused by the bacterium brucellosis, specifically Brucella canis in dogs that can cause infertility, abortions, and stillbirths. Brucella canis can devastate a kennel, and it is zoonotic, meaning it can infect humans. Handling infected canine blood, semen, or reproductive tissues can be a source of infection to humans.
Dr. Matthew Krecic, a diagnostics specialist for Zoetis, discusses brucellosis and how breeders can avoid this contagious disease in their kennels.
Symptoms Of Brucellosis
Clinical signs are often vague and non-specific if they develop at all.
Surprisingly, many dogs do not have any clinical signs of an infection, and because of the impact the disease can have on reproductive success -- all dogs involved in a breeding program, regardless of the absence of clinical signs, should be tested for the presence of brucellosis.
For stud dogs, some infected dogs will have epididymitis, scrotal enlargement (which can be painful), and scrotal dermatitis. For bitches, some will abort within late gestation without any other clinical signs.
Fetal abortion doesn’t always occur when an infected bitch delivers a litter of puppies. Some bitches deliver weak puppies. Reportedly, some bitches that have had unsuccessful pregnancies may still deliver normally in the future. However, these bitches may still in fact be infected.
While brucellosis affects the viability of the litter, it doesn't always affect fertility. An infected bitch will often continue to go into heat and breed.
Testing For Brucellosis
Several tests are available through veterinarians and commercial reference laboratories. These include rapid slide agglutination test (RSAT), agar gel immunodiffusion (AGID), and polymerase chain reaction (PCR). Culture of the bacteria is the gold standard test.
The RSAT identifies the presence of antibodies to combat the infection, not the bacteria themselves. One drop of a dog’s serum (blood collected, allowed to clot, and the clear fluid remaining is the serum) containing antibodies specific for Brucella canis combined with Brucella antigen, a piece of the bacteria, supplied with the test, agglutinates or adheres to the antigen, causing clumping that your veterinarian sees. This test is quite sensitive and veterinarians can have in-hospital results within two minutes.
If the dog tests positive, there is a second step that involves combining two drops of the dog’s serum to two drops of another reagent contained within the test kit. Then, this solution is combined with the Brucella antigen and clumping is once again determined within two minutes. If clumping is seen, the dog is presumed to be infected and it's recommended confirming by AGID, PCR, and/or culture.
If clumping is not seen, the dog may be early infected or not infected. In this situation, re-test the dog in three to four weeks with the RSAT.
Veterinarians often prescribe antibiotics but their success at resolving the infection is doubtful because the bacteria like to hide within the dog’s cells, and antibiotics are only moderately able to penetrate cells to clear all of the bacteria. Therefore, relapses of infection are common after stopping antibiotics.
Rather, the body’s own defenses through cell-mediated immunity are often better to clear bacteria that are within cells.
Infected stud dogs should be removed from the breeding program and neutered to reduce the risk of infection to humans (i.e. their owners, trainers, handlers, etc.). Humans can be infected by coming in contact with blood or other fluids from the infected dog. Infection in humans in the U.S. is rare, and can be determined through a blood test.
Infected bitches could seemingly “recover” and deliver normal litters in the future, but they may still in fact harbor the bacteria despite this. Therefore, transmission to her offspring in utero is probable.
Preventing An Outbreak
Prevention of any infection is so much easier than managing the consequences of infection. Prescribing and administering an antibiotic often does not resolve the infection, and no vaccine is available. Pre-emptive testing is therefore best.
Have your veterinarian test all dogs within your breeding program for brucellosis prior to every breeding and/or every 6 months, which is an ideal time for your veterinarian to also examine your dogs completely to ensure health, hopefully successful breeding, and healthy litters. The RSAT test is a fast, easy, and economical way to screen these dogs and hopefully prevent brucellosis from affecting your kennels.
Managing An Outbreak
A brucellosis-affected kennel is a challenge to manage. With guidance from a veterinarian, the kennel should be quarantined and infected dogs eliminated. If these dogs are to be treated and/or retained as pets, they should be neutered and moved to separate housing. Disinfect and handle dogs and their discharges/secretions, including urine, with gloved hands.
If a breeder suspects a brucellosis outbreak, they should contact their veterinarian who will provide a course of action.
Dr. Krecic completed his DVM at the Ohio State University, a master’s degree in veterinary science from Mississippi State University, and an MBA from the University of Florida, Warrington College of Business, and he is board-certified in small animal internal medicine through the American College of Veterinary Internal Medicine. Dr. Krecic served as a senior telemedicine veterinarian at IDEXX Laboratories before joining Zoetis in 2009 and continues to practice small animal internal medicine in his spare time.
The following information was originally released by the AKC Canine Health Foundation as a podcast on Jan. 23, 2014. If you prefer to listen to the interview, the podcast is available at www.akcchf.org/brucellosis-podcast.