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26 September 2000
MAF has issued St Bernard owners with precautionary recommendations to minimise the risks of disease spread while the Ministry continues to investigate a possible outbreak of canine brucellosis.
Canine brucellosis, is a significant reproductive disease in dogs caused by Brucella canis . It will be another five weeks before final test results are in. Results so far suggest that a genuine disease outbreak is unlikely due to a higher than expected number of false positive serology results coming through.
More than 70 dogs, known to have had contact with the dog that sparked this investigation, have been traced. These have all been tested, and 42 were found serologically positive on the screen test run in New Zealand. It is necessary to confirm the initial positive serology results with additional serology and bacteriology tests. Serology is generally used as an initial screening test because results can be known within 24 hours and can rule out dogs that are found to be negative.
The second serology tests are being done in New York, and the results of the first 15 initial screen test positive dogs have all proven negative there. Bacteriology tests are continuing in New Zealand, and MAF is waiting for results on the second batch of samples sent to New York.
"The screening test used in New Zealand is known to give around 10% false positive results, but the rate of false positives in this investigation appears to be much higher than that. The cause of this high number of false-positives from the initial screening test run in New Zealand is being investigated," says Derek Belton, MAF's Director of Animal Biosecurity.
Canine brucellosis primarily affects dogs, but can also affect humans, although cases in humans are sporadic and the clinical signs (headaches, chills, nausea and weigh loss) are mild. If confirmed, this will be the first case of the disease in New Zealand.
The investigation began late last month when a St Bernard dog in Wellington with an inflamed testicle was blood tested and found to have Brucella canis antibodies. Two other dogs were found to be positive at the same time. Two of the dogs had a clinical history consistent with canine brucelleosis in that both had been in close contact and there was a link to the United States were Brucella canis is widespread.
Until all results are in, MAF has issued general recommendations on the types of activities that carry the highest risk of transmitting Brucella canis from infected dogs, if it were proven to be present here. These recommendations are intended to assist dog owners to make informed decisions regarding management of their pets until there is further clarification of the situation.
Brucella canis is primarily a sexually transmitted disease. Unplanned mating should be avoided. Bitches in heat should be kept away from other dogs, and should not be sent to dog shows. Until MAF is able to confirm satisfactory performance of the serological test, testing prior to planned mating cannot be offered.
Fluids from aborting and whelping infected bitches are highly infectious to other dogs. They also present a risk to humans, so protective clothing, gloves in particular, should be worn by owners in such situations. Advice from a veterinarian should be sought if a bitch aborts, delivers stillborn puppies or suffers infections after whelping.
Infected male dogs may have an inflamed or swollen testicle/s. Urine from infected dogs can contain numerous bacteria during the early stages of infection, but contact with urine from an infected male dog is not considered to be a high risk for other dogs. Weeks of close contact are usually needed before infection can transmit from dog to dog via urine. However, puppies are more susceptible to infection through urine than adult dogs, and should therefore be separated from male dogs that may be infected.
Long periods (several months) of living together in close contact are typically required prior to transmission of Brucella canis from an apparently healthy adult dog to an uninfected dog. The risk of transmission from occasional or casual contact is very low. However, cautious owners may wish to minimise close contact between their dogs and others, and avoid sharing utensils between dogs from different households.
MAF wants to hear of any dogs, particularly St Bernards, with reproductive abnormalities consistent with canine brucellosis (abortions in bitches and testicular inflammation in dogs).
To report a case for investigation, contact the MAF National Centre for Disease Investigation exotic disease free-phone (0800 809 966).
For further information contact:
Dr Derek Belton, Director Animal Biosecurity, Phone 04 474 4125 September 2000