A recent study looked at human illness associated with raw pet food and has led to headlines such as “It is safe to feed raw pet foods.”

Did the study say that?  No, it did not.

If you asked 100 people if they had a foodborne disease in the past year, I assume few would say “yes,” despite the widespread estimate that about 30% of people get a foodborne illness every year. If you ask people if they got a foodborne disease from a specific food, the numbers would be even weaker / lower. People generally don’t have good recall for things like that, since we don’t usually recognize a cause when we get intestinal disease. The odds of someone linking their vomiting or diarrhea to their pet’s food are low, especially if they have no awareness that their pet’s food is a risk. Even if someone thinks about the source of their disease (which probably isn’t overly common), would they think about their pet’s food as the source, versus other foods in the house, versus a restaurant, versus anywhere else they ate? I suspect the average pet owner would not.

The problem isn’t the study, it’s how the study has been interpreted. It didn’t (and couldn’t) get a good estimate of the burden of disease associated with raw pet diets. The title of the study is Owners’ perception of acquiring infections through raw pet food: a comprehensive internet-based survey (Anturaniemi et al, Vet Rec, 2019). It looked at perceptions, which is useful, but has a lot of limitations.

The study was an internet survey of pet owners who fed raw diets. Internet surveys are easy to do, but are problematic for a few reasons. When you ask 1000 people to complete a survey and 990 respond, you know you captured your population well. If 10 respond, you know you haven’t and maybe you have a biased group of respondents (e.g. people that were more motivated / biased one way or another might be more likely to respond). With an internet survey, you generally have no idea how many people got the survey, and therefore no idea what percentage of people responded. The survey was disseminated through the research group’s Facebook page and through the researchers’ own academic, private and industrial contacts, so the people invited may not reflect the typical pet owning population. That doesn’t mean the results are useless (I’ve done internet surveys myself), it just means we need to be careful interpreting results. I tend to approach surveys as tools to get some basic information to figure out what questions to address more thoroughly, rather than tools to  answer specific questions.

The main question that was asked in this study was “Are there/have there been people in your household that have become sick from handling raw pet food or that have become sick from contact with a raw pet food eating pet?”

That’s a question we want to answer. However, it’s not a question the general public is well equipped to answer themselves.

  • The sample size was large (16,475 households), which is good, but there’s not much information about the households to determine how reflective they are of the broader population.
  • Most had been feeding raw diets for years, but some were pretty recent (e.g. 0.1 years, which is not much time for someone to get sick as a result).
  • Overall, 0.2% of households reported a “confirmed” transmission from the pet or food. That’s a relatively small number, but 0.2% per year means a lot of sick people. I’m actually surprised that people reported getting sick from their pet’s food at all. I’d expect massive under-recognition and under-reporting, so seeing any reports is interesting. If you consider that in most foodborne disease, reported cases usually account for less than 10% of the real number (and probably less than that here), the true burden of disease based on these numbers is quite a bit higher, to a level I’d certainly be concerned about.
  • Salmonella and Campylobacter were most the commonly reported infections. However, most of the time, there was no effort to confirm the pet food as the source, so it’s hard to say what the numbers really mean.
  • In situations where there was “confirmed” transmission, 31% of the time the pet was sick at the same time. That maybe strengthens the association between human and animal disease, but also maybe shows potential bias. Are people more likely to blame the pet/food if both they and their pet are sick at the same time, and blame human food or not consider pet food if the pet isn’t sick? I have no idea, but that could greatly influence self-reported data.
  • Interestingly, raw foods were handled in the same place as human food and with human food utensils significantly more often in the negative households. That’s the opposite of what I’d expect. The counter argument might be that people who handle raw pet food poorly are not tuned into the risks and are therefore less likely to identify or blame the pet food if they get sick.

The authors sum things up in a more balanced manner than internet headline writers:

“As a conclusion, this large study population from all over the world shows that the transmission of zoonotic pathogens might happen, but it seems to be sporadic. It is clear that the precise source of the pathogen is often challenging to find, which makes the interpretation of the result difficult. However, studies using different kind of approaches should be conducted in the future to be able to get a better understanding of the true risks or possible health benefits of feeding raw food diets to pets. This way the true pros and cons can be accurately analysed, before asking pet owners not to feed their pets with a nutritionally balanced raw diet.”

That’s a good conclusion. This study provides some baseline information and can help tailor future studies. It helps us figure out how to get a good answer rather than giving us a good answer now.

More information about ways to reduce the risk from feeding raw diets is available on the Worms & Germs Resources – Pets page.

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.

A recently published University of Guelph study evaluating pet poultry flocks found (unsurprisingly) high rates of shedding of certain concerning bacteria (Brochu et al, J Vet Diagn Invest 2019).

  • Campylobacter, an important cause of gastrointestinal disease in people, was present in 36% of tested chickens.  Salmonella was less common but present in 3% of chicken fecal samples.
  • The Campylobacter shedding rate was actually higher than has been reported in commercial chickens at slaughter plants.  This is in contrast to some statements you see about people not worrying about infectious diseases with small-flock chickens because they’re not from a “factory farm.”  As far as Campylobacter and Salmonella are concerned, chickens are chickens.

As the authors state, “Fecal shedding can lead to the spread of the pathogen within the environment, leading to contamination of food, tools, and materials coming into contact with people, flies, and other flocks. Given that small flock poultry are often kept as pets, close contact (e.g. kissing, petting) could increase the risk of exposure further, especially for people at higher risk (e.g. children). These results underscore the importance of proper sanitation and hand hygiene measures for flock owners to protect both flocks and the public from these pathogens.”

In a related note, the CDC has updated their Outbreaks of Salmonella infections linked to backyard poultry investigation notice.

  • As of August 30th, a total of 1003 people from 49 US states have been affected. Alaska is the only mainland state where cases have not been identified (the Alaskan climate probably not being great for outdoor poultry).
  • 23% of affected people are children under the age of 5, as is common in outbreaks like this, both because of their close contact with animals and their increased susceptibility to disease.
  • Two people have died and over 25% of diagnosed cases have been hospitalized. So, this isn’t just a case of having to spend a couple days running to the bathroom. It can cause serious disease, a fact that’s often overlooked.
  • Multiple Salmonella strains are involved, and affected people have reported getting chicks from a wide range of sources, including agricultural supply stores, websites and hatcheries.
  • Outbreak strains of Salmonella have been isolated from the backyard poultry environments at multiple homes, showing the potential for exposure without direct bird contact. This also highlights the potential for spreading Salmonella beyond the yard by other routes such as wildlife and runoff.

I’m not anti-backyard chickens. However, I’m against doing things illogically (or downright stupidly). Some basic common sense and infection control practices can limit (though never eliminate) the risk, but use of these precautions is likely inadequate. It’s a complex situation that doesn’t just deal with the chicken owners. It also relates to household visitors and even neighbours, since the potential for transmission of things from yard to yard can’t be dismissed. Ultimately, we need good guidance for backyard chicken owners and good compliance, and a realization that there are always risks and therefore necessary control measures. We’re working on this area but it’s not going to be a quick fix.

A number of Ontario fairs have cancelled horse shows because of concerns about strangles. Strangles is a nasty and highly contagious disease of horses caused by the bacterium Streptococcus equi, which is currently circulating in horses in Ontario (as in most places where horses are present). While most horses recover uneventfully from the infection, it’s problematic because of the potential for severe disease in a small number of horses and because it’s highly transmissible. Some horses that recover can continue to shed the bacterium in their nasal secretions, even after they no longer appear ill. This shedding can persist for a long time in some horses, when the bacterium sets up shop in the guttural pouches. These carrier horses are a big concern because they look healthy but are sources of infection for other horses.

Specific details are lacking, but reports of increased strangles activity in some areas have led to decisions to cancel equine events at cretain fairs.

  • The question that always comes up is “is it necessary to cancel the event?”
  • However, the question I focus on is “what is the most effective way to deal with this problem?”

I’m all for awareness and measures to reduce transmission of strangles and other diseases. However, the best way to do so is never clear. One approach is to cancel events altogether. Yes, that will prevent transmission, but is such a drastic measure necessary? It’s hard to say, but most often, it’s probably overkill. Sometimes that’s because there’s not really that much more strangles activity than normal, it’s just that there’s more publicized strangles activity. More importantly, it’s not the only way to control transmission. We can never completely prevent transmission at fairs or other events, but there are simple things that can be done to greatly reduce that risk.  Using these simple precautions more consistently is better overall for equine health in the area than sporadic cancelling certain events (and going back to previous, limited control practices).

It’s all pretty straightforward. Here is Weese’s “it ain’t rocket science” approach to strangles prevention at fairs (not that anything I say here is particularly new or something I can claim as my own idea… I keep saying these things but they’re rarely done in a sustained manner):

Owners

  • Don’t bring your horse to a show if it is sick or has been potentially exposed to a horse with strangles.
  • Take the horse’s temperature before the horse gets loaded onto the trailer. If it’s high, stay home.
  • At the show, use basic infection control practices. These including keeping your horse away from others horses, limiting contact of your horses with other people (whose hands may have been on other horses), avoiding sharing things like water buckets, being on the lookout for sick horses (and keeping well away from them). Some good ideas can be found in the Canadian National Farm and Facility Level Biosecurity Standard for the Equine Sector.

Event operators

  • Have someone (owners, or ideally an impartial person) take horses’ temperatures when they arrive. If they have a fever, they go right home. If it’s thought the high temperature might be from transportation, let them take the horse and trailer somewhere away from others for a while. If the temperature doesn’t come down…home they go.
  • If the horse has signs that suggest an infectious disease of any kind (not just strangles), such as a cough or runny nose, send them home.
  • Make it easy/possible for owners to implement the infection control measures mentioned above.

It’s all really basic stuff, which is why it doesn’t get done. There’s nothing flashy about it,  it’s just common sense, infection control 101. If these measures are implemented well, we’d greatly reduce the risk of strangles and various other infectious diseases at fairs and other equine events.

There’s nothing too surprising in the latest CDC update on the US outbreak of salmonellosis linked to pig ear treats. People continue to get sick, which is the frustrating aspect, since this has been a known issue for a while and has been communicated extensively.

At last report (yesterday), the total case number was up to 143. That probably means well over 1000 people have actually gotten sick, since the diagnosed cases likely include only the minority of cases that occur.

  • 20% of affected people have been children less than 5 years of age. Young kids are more susceptible to developing salmonellosis and are at greater risk of serious disease (which is more likely to be diagnosed), so it’s not surprising. Kids also tend to have very close contact with pets, and by extension their treats.
  • Thirty-three (33) people have been hospitalized.
  • People from 35 states have been affected.
  • Treats from many different suppliers have been implicated. So, it’s not a matter of just avoiding certain brands. It’s a matter of avoiding all pig ear treats. Actually, it’s a matter of avoiding all raw animal-based treats. You can buy a  bewildering range of dehydrated (but still uncooked and therefore high risk) animal bits as treats (e.g. lung, trachea, penis, liver) and they all come with risk of contamination with Salmonella and other bacteria. Whether pig ears are higher risk or they’re simply easier to implicate because they are more common isn’t clear.

Take home message

Avoid pig ear treats and any other treat that’s not cooked or otherwise processed (e.g. irradiated) to kill things like Salmonella.

There are others things that can be done to help reduce the risk when it comes to these items (e.g. avoid buying from bulk bins, wash your hands after handling treats, pay close attention to sanitary handling of dog feces, keep kids and high risk people away from pet treats) but ultimately this is a situation where we need to say no – just don’t feed them.  It’s not worth the risk.

I’ll hold back and just classify this as “not a great idea.”

At least 21 people in Macon, GA, are undergoing rabies post-exposure prophylaxis after having contact with a rabid raccoon.

How do that many people get exposed to a single raccoon?

Step 1: Take a wild raccoon and try to make it into a pet

  • Bad idea and illegal most places (including Ontario).

Step 2: Take it to a “Raccoon or kitten event” (whatever that is) where the public gets to play with it.

  • That’s it.  But should be followed up by…

Step 3: Talk to your insurance company because tens (or  hundreds) of thousands of dollars of treatment may be required.

Thirty-seven (37) people who visited the event had been contacted at last report, and 33 were considered potentially exposed to rabies through contact with this raccoon. Twenty-one (21) are undergoing post-exposure prophylaxis so far, and presumably (hopefully) the rest will be treated soon. That’s why standard guidelines say that rabies reservoir species like raccoons should never be used for public contact events.  Wildlife should be left in the wild.

As the Asian Longhorned tick (Haemophysalis longicornis) continues to spread in the US, we wait for it to make an appearance in Canada. This “exotic tick” was introduced to the US from Asia possibly a while ago, but was only first detected in 2017 in New Jersey.  It has since clearly established itself as a resident tick species in many states. It’s pretty much inevitable that it will make it to Canada, with southern Ontario or Quebec being the likely entry points.

This tick is a concern for a few reasons. One is that it’s an aggressive feeder. When you combine that with the biological quirk of females being able to reproduce without mating, you can get massive infestations of these voracious feeders on some animals, to the degree that species as large as cattle can die from blood loss.  (This is similar to what the winter tick (Dermacentor albipictus) can do to moose.)

Haemophysalis longicornis can also be the vector of a various infectious diseases of people and animals. Which diseases this tick can transmit in North America is an current area of investigation, since importation of the tick doesn’t necessarily mean all the potential diseases were also imported. We don’t know the extent of that risk yet.

So, what about companion animals?

There are a few issues to consider with dogs and cats when it comes to this tick as well. One is the potential for health effects from massive tick burdens. Hopefully the risk of serious effects from that is lower than in wildlife and livestock since pets are usually monitored more closely, but it’s still a concern. Disease threats are still pretty unclear at the moment but can’t be dismissed.

The other issue is the potential for pets to act as sentinels for this tick. If you look at the USDA’s latest Situation Report on H. longicornis (including the images above), dogs are #3 on the list of most commonly identified hosts, after the environment and white-tailed deer. This is the case despite any formal surveillance directed at this tick in dogs. It’s not particularly surprising since dogs can spend time in tick-rich areas, running through sites where ticks are looking for a host. As a low-to-the-ground haired species, they can pick up ticks quite easily, and a tick on a dog may be more likely to be spotted than a tick on most other species.

Back to Canada…

The fact that this tick entered the US first has given us a head start for planning, and there are various activities underway to optimize the response to this tick when it’s found, including detection, identification, testing, and communication. The key first step, though, is finding the tick, and finding it as early as possible. Here’s where dog (and cat) surveillance can come in. Since dogs can be such great sentinels for ticks, it’s quite possible we’ll find it first on on dogs – if we’re looking, and communicating.

There are a variety of ways this kind of detection might happen, such as:

  • An owner finding a tick on their dog and taking it to their vet, who realizes it’s different than a typical tick and sends it off for further investigation.
  • A submission to a surveillance program such as our PetTickTracker or, for some provinces, eTick.
  • A tick found as part of ongoing pet surveillance such as our Canadian Pet Tick Survey (active surveillance through participating vet clinics) or our Lifetime Lyme Study.

Tick surveillance is a great example of the potential impact of citizen science. A curious veterinarian or pet owner might be the first to find this tick, allowing a quicker intervention than if we relied solely on traditional sources.

Tick image: https://www.cdc.gov/ticks/longhorned-tick/index.html

It wasn’t a snake and Samuel L. Jackson (presumably) wasn’t there to save the day, but Spirit Airlines passengers on a recent flight had to deal with an unwanted stowaway. During a flight from Charlotte to Newark, a bat started flying around the cabin of the Spirit Airlines aircraft. It likely flew into the plane through an open cabin door at some point and hid out for a while, emerging halfway through the flight. The bat was likely as distressed as the people by its presence in that abnormal, confined space, so it flew around for a while, eventually being caught with a cup and a book, and locked away in a bathroom.

That’s a pretty good way to handle it if you can catch the bat without being bitten. Otherwise, leaving the bat alone makes the most sense, as it’s unlikely to land on or bite anyone, but the passengers would probably have been less impressed with that approach.

Upon landing, the bat was taken away by animal control.  It was presumably euthanized since releasing wildlife well away from where they originated is not commonly done, particularly due to disease transmission risks.

When bats are involved, rabies obviously gets discussed as bats are a prime source of rabies exposure in North America. But, what’s the risk?

  • For rabies to be a concern, the bat has to be rabid (prevalence is usually only up to a few percent in any given bat population) and you have to get bitten (largely avoidable). Aerosol exposure (breathing in rabies virus) is a concern is densely populated bat caves, but I can’t see a single bat (if it was infected) in a space that size, with that exceptional ventilation that is present on modern airplanes, posing any plausible risk.

Realistically, your biggest health risk is probably the concussion you might get from your neighbour who’s freaking out and frantically swinging his laptop.