Media reports have described a number of Norwegian dogs with unknown intestinal disease, characterized by vomiting and diarrhea. Cases were first reported in Oslo, with subsequent reports in other towns – whether this indicates spread of disease or spread of awareness isn’t clear. Oslo could be the epicentre of the disease, but it could also simply be the first place it was identified, based on the presence of more dogs and more veterinarians. Some affected dogs have died. Details are sparse and other information I’ve been getting doesn’t yet provide much more insight, but it’s obviously something worthy of attention.
First thoughts that come to mind for something like this are:
Is this infectious?
Even though we jump to an infectious cause, this isn’t always the case. In particular, a toxin has to be considered. This is where getting information about common exposures (places visited, food and treats affected dogs have consumed) is critical.
If it’s infectious, is it something new?
Common things occur commonly. Most “strange” disease issues end up being unusual manifestations of common problems, rather than emergence of a new problem. However, infectious diseases continue to emerge, so while we should focus on the usual suspects we still need to think about the potential for something new.
Testing for infectious intestinal diseases in dogs (and most species) can be a challenge. The gut contains a wide range of bacteria, viruses and parasites. Most of them are actually good, or are at least harmless. Some can cause disease but usually don’t, and are commonly found in healthy animals. Some are more strongly linked with disease, but rarely do we have absolute causes, i.e. something that we find and we can definitively say is a problem for that individual animal.
As a result, testing can be extensive, expensive and low yield. In a single adult dog with sporadic diarrhea, we tend not to do much testing, because it’s hard to get a clear answer and it usually doesn’t change what we do. A potential outbreak or new problem is different, and it makes sense to put more time and effort into testing to try to figure out the cause of the problem.
In situations like this, we usually work to identify the usual suspects first (e.g. parvovirus, Salmonella, Campylobacter), as well as suspects that we’ve more recently identified as being problems (e.g. NetF-producing Clostridium perfringens). Broad testing that looks for things that are less convincing causes of disease (e.g. circovirus) can be useful if results are given the proper context, realizing they might be innocuous or only relevant when another cause of disease is also present . Simply finding a bacterium, virus or parasite in a patient doesn’t necessarily mean anything for that animal. Looking at results across lots of affected individuals, comparing results to what we know about different populations, and comparing testing results and clinical patterns to those of diseases we know can get us useful information. It’s not unusual to think that there’s a new important cause of diarrhea, only to realize with further study that it’s just a harmless background bug that we hadn’t bothered to pay attention to before.
More information will hopefully be available in the near future.