We don’t hear about rabies being mentioned very often but when we do there is a scary connotation attached to it. It is virtually always fatal to all mammals and zoonotic to humans with no curative treatment once clinical signs develop. Only prevention through vaccination and prevention from contact by strong surveillance programs have kept rabies at a fairly low incidence across Canada.
The biggest reservoirs for the disease across Canada are bats, skunks, raccoons and foxes (red and arctic). It varies across the country but Alberta has the most reported cases in bats followed by skunks and then cats. Up north the arctic fox can be the source and in Ontario we have diagnosed cases in foxes, raccoons and other animals. As of April 1, 2014, even though it is still a reportable disease for veterinarians, the Federal Government downloaded the responsibilities for rabies control to individual provinces. This came suddenly out of a budgetary issue in 2012 with no consultation with our national veterinary group or other affected parties. This is called passing the buck.
Three other diseases were also dropped or downloaded including anthrax since it was costly to deal with and considered endemic in Western Canada.
Rabies, however, could be considered the most serious zoonotic disease and could put anyone involved in veterinary medicine, agriculture and even urban folk at severe risk if they come in contact with a rabid animal.
Provinces have taken over handling of the potential cases; however, the federal government lab still does the testing.
Globally, rabies kills 55,000 people annually, mainly in Africa and Asia, so it is critical we maintain surveillance to keep people, pets and farm animals protected.
Veterinary clinics and the medical officer of health are still involved with cases of human exposure from bites by rabid domestic or wild animals.
Everyone needs to be on the lookout for animals exhibiting abnormal symptoms of aggression, varying forms of paralysis including inability to swallow and salivation. Lethargy, vomiting and anorexia are non-specific signs also observed with rabies. Other signs can include incessant bellowing in cattle. Once clinical signs develop, affected animals will die within 10 days, and that is a fact.
If you run across a suspicious animal exhibiting these clinical signs contact your local veterinary clinic, as they become your first line of defense.
Keep in mind rabies is rare, and many other diseases mimic rabies. For that reason, when veterinarians see any of the clinical signs listed above, rabies is always on the differential list.
For instance, cows with wooden tongue or choking salivate excessively and these two conditions are treatable yet could at first glance indicate rabies. Likewise, choking horses salivate profusely.
Still, it pays to remain cautious. Just because you haven’t heard of it or diagnosed it in a while doesn’t mean it’s not around. Years ago I had a client who came across a live bat on his lawn in daylight hours acting very peculiar and unable to fly. It was submitted for testing and came back positive for rabies. Since bats are the main reservoir in many areas it’s always advisable to vaccinate dogs and cats.
In other areas of the country such as Manitoba or Ontario, horses and even cattle are vaccinated in high-risk areas or when they are going into high-risk areas.
There are two forms of rabies, the furious form and the paralytic form. Horses, cattle and bats generally get the paralytic form, cats the furious form and dogs can get both. The movie “Old Yeller” vividly showed the aggressive form in a dog.
The World Health Organization categorizes rabies exposure to three different levels. The first, contact due to feeding, touching or licking by a rabid animal on intact skin is not considered a danger of exposure to the rabies virus. The second and third categories involve exposure due to minor scratches up to full depth bites and licking on broken skin. These are considered dangerous and warrant immediate medical care and followup guidance from the public health officer.
We are lucky in Canada with good surveillance and vaccination of most pets or production animals in high-risk areas the incidence of rabies remains quite low.
Rabies remains a reportable disease so while the provinces look after the surveillance the Canadian Food Inspection Agency (CFIA) logs the cases found across the country.
In 2017 CFIA tested 2,775 samples for rabies virus. Of those, 239 were confirmed infected. More than half (149) were submitted from Ontario, primarily raccoons (86), skunks (37) and bats (20) along with four head of cattle. Two infected cattle turned up in Manitoba and one in Saskatchewan.
As a side note, birds, amphibians and reptiles can’t get rabies and rodents only rarely. Everyone, including livestock producers, pet owners, wildlife officers, public health officials and veterinarians, needs to be ever vigilant for the possibility of rabies appearing. The press is very good at reporting positive cases and the location. This is another reason to be in touch with your veterinarian as they are the only ones allowed to handle rabies vaccine. This is one disease where surveillance really helps to keep the incidence as low as possible.
Always get an animal under your care (cat, dog, cow or horse and other domestic animals) checked out if it develops weird neurologic signs or aggressive behaviour or lethargy. Wildlife in the form of skunks, bats raccoons, or foxes exhibiting unusual behaviour or found dead should be submitted for rabies testing, too. You help the rest of the population out (human and animal) if you take on this responsibility.
Remember, preventative vaccines are very protective and different vaccines have different years of duration in our domestic pets. In areas where rabies are endemic, horses especially, may be vaccinated. Rabies is considered one of the core vaccines in equine. Cattle vaccination will depend on incidence and location.
Dr. Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.