Bluetongue has been detected in a 3.5-year-old dog. The animal lived on a Dutch dairy farm with both cattle and sheep. Research by Wageningen Bioveterinary Research (WBVR, part of Wageningen University & Research) showed that the animal was infected with bluetongue virus type BTV-3/NET2023, the same virus currently found in sheep and cattle in the Netherlands.
The dog was seriously ill and showed shortness of breath, pulmonary oedema, severe emaciation and lethargy, among other symptoms. Based on the symptoms, the veterinarian reported a suspicion of bluetongue to the NVWA. Samples taken from the sick dog were examined by WBVR for the presence of bluetongue virus. “The PCR-test detected BTV. Partial sequencing confirmed BTV-3/NET2023 in the samples,” says WBVR researcher Melle Holwerda. In addition, the sample was tested for Brucella spp. This test was negative.
“Bluetongue infection in dogs is really very rare,” according to Holwerda, head of the National Reference Laboratory for vector-borne viral animal diseases. “In the scientific literature, a few anecdotal cases of bluetongue-infected dogs have been reported.” The observations are not specific for certain dog breeds. Remarkably, these described cases were almost exclusively pregnant dogs. The bluetongue virus-infected dog in the Netherlands was also a pregnant.
Presence of virus
Little is known about a possible infection route of bluetongue in dogs, Holwerda says. “The scientific literature also offers few leads on this.” The infected dog lived on a livestock farm and was able to roam around freely. The animal had access to the stables and feeding parlours, and possibly also to colostrum or an afterbirth. At the time the dog became seriously ill, the livestock farm was not known yet to the NVWA as affected by BTV. Veterinarians from the NVWA and Royal GD visited the farm did not not notice diseased cattle or sheep. PCR-results of samples taken from the farm animals confirmed two BTV-3-positive cows. “This proves that the bluetongue virus was indeed present on the farm,” said Holwerda.
Route of infection
Bluetongue virus can rarely be found in dogs and wild carnivores, Holwerda knows. The presumed route of infection of these animals is eating raw meat or the afterbirth from BTV-infected ruminants or drinking colostrum which is contaminated with BTV-containing blood. “But transmission through a blood meal from an infected midge cannot be ruled out as an introduction route either.” Holwerda stresses that for this particular Dutch dog, the route of infection cannot be conclusively determined.
The virus won’t spread further via a dog. “Dogs are not a source for onward virus spread,” Holwerda explained. Bluetongue is not a disease that can be transmitted from animals to humans.
“Bluetongue is common in worldwide. However, dogs with bluetongue infections are very rare. We therefore consider the likelihood of infection of dogs with bluetongue extremely low,” Holwerda said. However, alertness is still needed, especially with pregnant dogs that have access to afterbirths of infected cattle and sheep. “We recommend restricting dogs from the barn on farms and not allowing access to the calving pen. This prevents dogs from coming into contact with any afterbirth or blood from an bluetongue-infected animal.”