Discospondylitis caused by Brucella canis in a dog imported to Sweden

Brucella canis is a zoonotic bacterium, causing mainly reproductive disorders and discospondylitis in dogs, but infections may also be subclinical. Mating is one of the main transmission routes, putting breeding dogs and stray dogs at risk of infection. Confirmatory diagnosis relies on positive culture or PCR. This is difficult to achieve due to intermittent and low-level bacterial excretion. Serological testing might give rise to both false negative and false positive results, making interpretation difficult. Since the first reported Swedish case 2011, the infection has been confirmed in a handful of cases, predominantly in breeding dogs. Several reports highlight the risk of brucellosis in dogs imported from Eastern Europe. This case study describes a one-year-old intact male dog originating from a dog shelter in Romania, which was presented to a veterinary hospital in Sweden with signs of pain of unknown origin. A suspicion of B. canis was raised based on clinical signs and history of the dog. Serological testing by enzyme-linked immunoassay for B. canis was positive. Resolution of clinical signs was not achieved despite treatment by robenacoxib and pregabalin. The dog was euthanised and sent for necropsy, showing a chronic multifocal prostatitis and a spondylosis-like, ossified change over L1–L2 in the lumbar spine. Infection was confirmed by positive result of two PCR tests, targeting the IS711 insertion sequence of Brucella spp. Four contact dogs were examined because of the confirmed infection. None of these dogs showed clinical signs of disease. Three of the contact dogs were positive on one or more test for B. canis antibodies. One of the seropositive contact dogs was euthanised and sent for necropsy. A mild generalised lymphadenitis was noted, but B. canis could not be confirmed. This is the first described Swedish case of B. canis in a non-breeding dog. The case highlights the complexity of canine brucellosis, including the array of clinical signs and the multiple diagnostic methods that may be necessary to confirm an infection. It also shows the risk of introducing infections through cross-border transportation of dogs.