Investigation of possible Brucella canis underway

5 September 2000

The Ministry of Agriculture and Forestry (MAF) is investigating a suspected outbreak of Brucella canis, the cause of canine brucellosis.

If confirmed, this will be the first occurrence of this disease in New Zealand. Brucella canis primarily affects dogs, but it can also infect humans.

Human cases are sporadic and the clinical signs (headaches, chills, nausea and weigh loss) are mild. The Ministry of Health has been notified.

The investigation began when a St Bernard dog in Wellington with an inflamed testicle was blood tested and found to be serologically positive for Brucella canis (i.e. the blood sample showed evidence of Brucella canis antibodies).

The infected dog was born in New Zealand as the product of semen imported from the USA, where Brucella canis occurs widely. A second St Bernard bitch imported from the USA and resident in the same household also tested positive, as has the bitch's daughter. All imported dogs to New Zealand are tested for Brucella canis, as are semen donors.

The Brucella canis diagnosis is currently presumptive as approximately 10% of dogs may return a false positive Brucella canis serological result due to cross-reactions with a number of common bacteria. There is evidence that some large breeds of dog may have an even higher false positive rate than this. MAF is attempting to secure a definitive diagnosis by isolating the bacteria through culture. The circumstances, however, make canine brucellosis a distinct possibility and as such MAF is conducting a detailed investigation within the framework of an exotic disease response. The owners of the test positive dogs are keeping them isolated from all other dogs. St Bernard dogs in New Zealand that may have had contact with the infected dogs are under investigation.

Brucella canis is sexually transmitted by the mating of infected males and females. The infected female usually appears healthy with no signs of disease or indication that she is a carrier of the bacteria. She can spread brucella to other animals through her urine, aborted pups, or more commonly at mating. Once pregnant, the bacteria will also infect the developing foetuses causing illness. An infected male can spread the brucella bacteria via his semen.

Litters of infected bitches are often aborted in the last two weeks of gestation, or the puppies may die shortly after birth. The aborted pups are usually partially decomposed and accompanied by a grey to green vaginal discharge, which can contain high levels of bacteria. People should avoid contact with dead foetuses or discharges from aborting dogs.

Currently MAF's investigation is focused on St Bernards. The Ministry wants to hear of any reproductive abnormalities in this breed that may be consistent with canine brucellosis (in particular, abortions in bitches and testicular infections in dogs). To report a case for investigation, please phone the MAF National Centre for Disease Investigation (0800 809966) and inform the operator that the query is to do with the canine brucella investigation.

For further information contact:

Derek Belton, MAF Director Animal Biosecurity. Telephone: (04) 474-4155
Gita Parsot, MAF Communications, telephone N/A

Contact MPI

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