In December 2010, a 3-year-old American Staffordshire terrier imported from Poland, expecting her first litter, was brought to the Regional Animal Hospital of Helsingborg, Sweden. She was 46 days pregnant but although her general condition was good, she had a green vaginal discharge. An ultrasonography was performed which revealed that all pups were dead. The bitch was aborted with aglepristone and prostaglandins, and also received amoxicillin. Hematology showed mild leukocytosis and moderate eosinophilia. Bacterial culture from the vagina showed no bacterial growth. The bitch was monitored with ultrasonography and clinical examinations for the following weeks. Her general condition was good and the discharge ceased rapidly. No foetal parts could be identified in the discharge.
In the follow-up of the abortion the owner reported that the bitch had been mated in Poland, and that she had been mated once previously with a dog from Serbia, although she did not conceive at the time. This led to the suspicion of brucellosis, and the bitch was tested serologically for B. canis in January 2011, with a negative result. An analysis for Giardia and a Baermanns flotation test for parasites were also negative. The owner was recommended to vaccinate the bitch against canine herpesvirus at the next mating, and to follow progesterone levels during the next pregnancy.
In the end of May 2011 the bitch was again presented at the animal hospital. She had been taken to Poland for mating to the same dog again, and now had a bloody discharge at day 59 of pregnancy. Ultrasonography was performed and all but one pup were dead. A caesarean section was performed, but no pups were alive. Ten dead, partially autolysed pups were delivered. The uterus was filled with a brown-greenish discharge and all pups had cutaneous ulcerations. The bitch was treated with amoxicillin and cabergolin, and recovered uneventfully. This second abortion in the last trimester in a clinically healthy bitch mated abroad again raised the suspicion of brucellosis, and the placentae from aborted foetuses were sent to the National Veterinary Institute (SVA) for bacteriological analysis, specifically asking for B. canis.
The culture result from the placentae was positive. As this was the first case of B. canis in Sweden, the strain was sent to EU-RL (European Union Reference Labaratory) in Alfort, France, for confirmation. The bitch was also tested serologically, and was now positive for B. canis. The Swedish Board of Agriculture (JV) decided that the bitch had to be isolated until a definitive diagnosis was made (confirmation by EU-RL); they initiated contact tracing and contacted the county veterinarian and the county medical officer. The bitch was tested again by blood culture, vaginal culture and serology (RSAT). B. canis grew in the blood culture and in the vaginal culture, and the bitch still had antibodies to B. canis. The first bacteriological culture was confirmed by the EU-RL. The Swedish Board of Agriculture decided that the bitch should be euthanized, as recommended by SVA. The bitch was euthanized at the Regional Animal Hospital of Helsingborg.
SVA recommended how and which dogs to test, and JV had the main responsibility for the contact tracing. Dogs within the country that had been in contact with the infected bitch through mating, common housing or other close contact, were tested. All in-contact dogs were tested twice, with cultures from blood and the genital tract, and by serology. At least one of the occasions should be minimum 12 weeks after the latest risk contact. At least one sample from the genital tract should be during oestrus in bitches, and semen was cultured from the male dogs.
Possible sources of infection included the two dogs that had mated the bitch. The first dog that had mated the bitch, when she did not conceive, had been sold to Sweden by this time and was a stud dog in northern Sweden. There was a history of bitches not conceiving after mating with him. A semen sample in October 2010 revealed azoospermia, macrophages and epithelial cells in the small ejaculate of 1 mL. In July 2011 the total sperm count was 115 million, with 60% sperm having various unspecified defects and an abundance of epithelial cells. Two months later, in September, the total sperm count was 1265 million, 75% progressive motility and 10% unspecified defects. In November 2011 a new semen sample was taken and evaluated. The total number of sperm was good (1700 million), their motility was good and defects were within normal limits. Epithelial cells and leukocytes were also within normal limits. He was tested for B. canis in July, September and November 2011 by blood and semen culture and by serology (RSAT), and in November semen was also analysed by PCR. In-contact dogs to this male dog were tested in the same way as in-contact dogs to the bitch. In total, 15 in-contact dogs of different breeds were tested with no test results being positive. The contact tracing is schematically described in Figure .
Figure 3 Schematic figure describing contact tracing. The bitch within the red circle is the one diagnosed with B. canis. Male dog within blue circle: the first dog (from Serbia) that mated the bitch and that now lives in Sweden. Thick arrows: contact through (more ...)
In Poland, the male that mated the bitch the second and third time was serologically tested (RSAT) twice during the autumn 2011, with negative results, and he is still being used for breeding in Poland. He resides in a kennel. The Brucella status of the other dogs is not known.