The rabies-related response to a bite is nothing new, but it still causes a lot of confusion
mouthy dog showing teeth
No, we haven’t changed to a cooking blog, I’m talking about bites of the canine variety. I can’t think of any specific data that would show it, but I wonder whether bites are more common around the holidays, with disrupted schedules and more visitors (and a potential midnight intruder in a red suit).
The rabies-related response to a bite is nothing new, but it still causes a lot of confusion so I’ll re-hash it here. Rules vary a bit (no pun intended) by jurisdiction so relevant personnel (e.g. public health, animal health) should be contacted, but here’s the general response when a dog bites a person.
What’s the concern?
- Rabies exposure from dog bites in areas where canine rabies is widespread (e.g. Africa, India, China) is a major concern. In other areas (e.g. Canada, the US), rabies is very rare in dogs. However, since rabies is almost invariably fatal in people, we don’t mess around. The immediate concern is to figure out whether the dog might have been shedding rabies virus in saliva at the time of the bite.
- Rabies isn’t the only problem, as trauma from the bite and various other infectious diseases are also of concern, but we’ll focus on rabies here.
What happens to the dog?
A 10-day observation period is pretty much universal. This can be a strict quarantine or less formal confinement, with the key being to keep the dog under control and make sure it’s normal 10 days after the bite.
What is the purpose of the observation/quarantine period?
Shedding of rabies occurs quite late in course of infection. The virus has to travel through the body from where the dog was bitten, via nerves, to the brain, and then through nerves down to the salivary glands, at which point the dog becomes infectious to others. Therefore, by the time rabies virus can be shed in saliva, it’s already been in the brain for a little while. When it reaches the brain, signs of rabies develop pretty soon thereafter due to damage caused by the infection. So, if a dog is still neurologically normal 10 days after the bite, it would not have had rabies virus in its saliva when the bite occurred.
What if the dog is vaccinated against rabies?
- It doesn’t really matter. The vaccination status does not generally impact the response to a dog that bites someone (it does change the response if a dog is bitten by something else (e.g., fight with a raccoon) and is potentially exposed to rabies).
- Rabies vaccination is very effective but given the severity of rabies, we can’t assume that it’s impossible for a vaccinated dog to have rabies.
What happens if the dog is not available for observation/quarantine?
If the dog can’t be identified and quarantined, you can’t rule out rabies. Therefore, it ends up being a discussion of the likelihood of rabies and whether post-exposure prophylaxis is indicated. Usually, the default is to treat it as exposure even if it’s very unlikely, since post-exposure prophylaxis is very effective and rabies is very bad.
What if the dog can’t be observed/quarantined?
If there’s a health or safety reason that quarantine can’t be done, euthanasia is indicated. This allows for testing of the animal’s brain, which is the only definitive way to determine if the dog had rabies at the time of the bite. Quarantine is preferred from a dog welfare standpoint, obviously, and it’s also best for the person in most situations. If the dog is alive and clinically normal in 10 days, rabies is not an issue. If the dog is euthanized, there is always the low (but possible) chance of an equivocal test, or, as I wrote about last year, a brain that gets lost in transit.
The big thing that often gets overlooked is consideration of why the bite happened in the first place. This is important to help prevent it from happening again. It involves thinking about potential health or behavioural problems in the dog, poor supervision or poor handling on the part of the people involved. Bites shouldn’t be dismissed as an unavoidable consequence of dog contact.