By Dr. Ron Harrison, DVM
Martin Coffman, DVM, of the Iams Company, was quoted saying the following on brucellosis infections. “In the 1970’s, as a young veterinarian and a beagle field trialer, I was intimately involved in the epidemic of Canine Brucellosis that wreaked havoc in that breed. While I never had a case in my own dogs, I saw the effects of this disease in many kennels. Lifetime breeding programs were wiped out and many kennels never recovered from the losses incurred as a result of sterility, abortions, and weak newborn puppies that resulted from this infection. Great young stud dogs with their producing career in front of them were lost to the beagle breed as well as the crucially important brood bitches in major breeding kennels. As a result of this epidemic in the beagle breed, increased awareness led to preventive steps that eventually curtailed the problem but breeders of other hunting dogs, e.g. bird dogs, assumed the problem was just in the beagle breed and for decades have minimized the danger this disease carries. The reality is that any dog can be infected with the brucellosis bacteria, and it lurks as a threat to all breeders of all breeds. Since the disease can be transmitted by direct contact with infected dogs and hardware like bowls, leashes, truck boxes, and training collars, all dogs that assemble in large numbers, e.g. at a field trial are especially susceptible.”
Canine brucellosis is an infectious disease caused by the Brucella bacteria. The illness in dogs is caused by Brucella canis (B. canis). However, Brucella organisms commonly associated with other animal species, such as Brucella suis (pigs) and Brucella abortus (cattle and bison), can infect dogs depending upon their exposures to these species.
Signs of brucellosis in infected dogs include: in female dogs, brucellosis causes abortion and infertility. Females may fail to get pregnant or may lose their litters in late pregnancy (45-55 days). After abortion, females may have a prolonged vaginal discharge. In males, infertility can result from brucellosis affecting various reproductive organs including the prostate, testicles, and epididymis. A brucellosis infection may result in an inflamed prostate, swollen or shrunken testicles, and swollen epididymis. Nonspecific signs that may affect both sexes include lethargy, unwillingness to breed, and inflammation of the lymph nodes. Dogs may not show any signs or symptoms of the disease. Animals may get an infection in the bones or joints and show signs of back pain or arthritis. Infections may also occur in the eyes.
B. canis is a sexually transmitted disease in dogs. Dogs become infected through exposure to secretions during mating or by contact with infected tissues during birth or following abortion. In addition, dogs may spread bacteria in urine, saliva, nasal and ocular secretions, and feces. Infection with B. suis can occur in dogs that have contact with feral hogs (e.g., hunting dogs) following exposure to blood, urine, saliva, or other tissues. Exposure to B. abortus may occur if dogs have contact with aborted tissues of infected cattle or bison.
However, most domestic cattle herds in the U.S. are now free of brucellosis making this route of exposure very unlikely. Brucellosis is still present in cattle in Texas, Wyoming, and Idaho.
It is very difficult to cure an infected dog. The bacteria can get into the bloodstream and infect other parts of the dog’s body, such as joints and bones. Depending upon the type of brucellosis, pet dogs may be spayed or neutered and treated with a long course of antibiotics at the discretion of the pet owner and treating veterinarian. However, relapses may occur resulting in shedding of bacteria. Consequently, treatment is not recommended in any case due to the contagious nature of brucellosis and the threat to human health.
The good news is that canine brucellosis is easy to prevent. Before breeding your dog, both the female and male dogs should be examined and tested by a veterinarian. The test involves a simple blood test. Licensed breeding facilities should have all new additions tested for brucellosis before bringing them onto the premises. These animals should also remain isolated until a second negative test is obtained at least 4-6 weeks later. Dogs should not be bred if they are infected with canine brucellosis. Dogs known to be exposed to feral hogs should be tested periodically to detect any early infection.
Brucella bacteria can infect humans. However, the Brucella organisms vary in their rate of infectivity. For example, B. canis rarely infects people and causes very mild illness in those persons who do get infected. Only people in contact with very high numbers of bacteria, such as dog breeders or those in research or diagnostic laboratories, are considered to be at risk for B. canis infection. However, people who are immune compromised due to illness or immunosuppressive therapy and children or pregnant women are vulnerable to brucellosis. B. suis, on the other hand, more commonly infects exposed people and causes more severe illness.
The risk of acquiring canine brucellosis from a dog is very low in most situations. Canine brucellosis can spread to humans by close contact with secretions from the reproductive tract, such as aborted puppies, urine, or vaginal secretions from infected dogs. Infection usually results when infected tissues or secretions come in contact with broken skin or are accidentally ingested.
Depending upon the Brucella species, symptoms are often mild and nonspecific. Most commonly a continued, intermittent, or irregular fever accompanied by headache, weakness, generalized aching, and lymph node enlargement characterizes human infection. In more severe infections, joints, bones, or heart valves may be affected. Individuals exhibiting any of these symptoms should seek medical attention. Signs of illness can occur within one week to several months after exposure. On average, signs will begin within 3-4 weeks following infection.
Protective measures should be taken to prevent contact with reproductive secretions, urine, and tissues (such as an aborted fetus) of infected dogs. Make sure latex or rubber gloves are worn when handling high risk materials and cleaning affected surfaces. Face masks and eye protection should be worn to prevent any material from entering the mouth or eyes when disinfecting kennel areas, especially if the person is immune compromised. Any infected animal should be placed in quarantine or isolated facility until the testing is complete. Avoid exposure to stray or feral dogs.
Brucella organisms are not very hardy outside of a host animal and are sensitive to direct sunlight and desiccation. Contaminated wet areas should be dried and disinfected when possible. Disinfection is effective with any of the following: 1% sodium hypochlorite (bleach), 70% ethanol, iodine/alcohol solutions, glutaraldehyde, or formaldehyde. Breeding dogs should be purchased from known brucellosis-free kennels. All newly acquired dogs should be isolated and tested twice at least 4-6 weeks apart before they are incorporated into the breeding group. All breeding dogs in a facility should be tested yearly at the same time. Dogs bred intensively outside the facility should be tested 2-4 times per year. Females should be tested at least 3 weeks prior to the onset of heat, to allow time for a confirmation test if the screening test is positive. Testing is more accurate near or during heat because there are more bacteria circulating in the bloodstream during these times. Quarantine, testing, and euthanasia of infected dogs are the primary methods necessary to eliminate and prevent the spread of disease in a commercial breeding facility. Reported cases in a licensed facility will likely result in quarantine of the facility to prevent the spread of disease and determine the possible source of infection. During the quarantine period, breeding dogs should be housed separately. The owner may opt to humanely euthanize Brucella suspects to minimize the time in which the facility is quarantined.
Sources for this article include:
■ Martin Coffman, DVM, The Iams Company
■ Georgia Department of Agriculture
■ U.S. Centers for Disease Control and Prevention