I did a talk recently for Third Age Learning in Guelph, and there was an abundance of questions. I didn’t get through them all at the time, so I figured I’d address some of them here:

Do mice carry rabies?

Mice aren’t rabies reservoirs like raccoons, skunks or bats, as they don’t have a rabies virus strain that circulates in the mouse population. Like any mammal, they are susceptible to rabies and can be infected. However, most often when a mouse tangles with a rabid animal, it doesn’t end well for the mouse. If a mouse survived a bite from a rabid animal it could get rabies, but since that’s pretty uncommon, mice are low risk.

Can you talk about foot-and-mouth disease? I heard of someone recently dying from it.

This is another one of those situations where diseases have confusing names.

Foot-and-mouth disease is a viral disease that affects cloven-hoofed animals such as cattle, sheep and pigs. It’s a devastating disease for those species, but of very limited risk to people. The odd human infection has been reported but it’s not really considered to be a significant human health risk.

Hand foot and mouth disease is a completely different disease caused by a completely different virus.  It only affects people, and usually, it causes mild disease characterized by oral lesions and a rash on the and feet in kids. Adults can sometimes become infected and serious infections (including death) can occur, but that’s very rare.

Do skunks pose a problem for cats that walk in the same area?

Not really. Rabies is a concern with skunks but that’s transmitted by bites, not by simply being in the same area (and cats are generally smarter about avoiding skunks compared to dogs).

A more realistic concern would be leptospirosis. Skunks can shed Leptospira bacteria in urine and that can contaminate the environment. We uncommonly see (or at least diagnose) leptospirosis in cats. It’s much more common in dogs, and can also affect people. Overall, though, the risk to cats posed by skunks being in the vicinity is pretty low.

How do you test a raccoon population for rabies?

It involves testing a sample of individual raccoons. Rabies testing in animals requires a brain tissue sample, meaning the animal can only be tested after it’s dead. Raccoon testing is routinely performed when there has been exposure of a person (or sometimes a domestic animal) to the raccoon. It’s done in these cases to make sure the raccoon wasn’t rabid, as that influences management of the person or animal that was bitten/exposed. Beyond that, testing of dead raccoons is sometimes performed for surveillance purposes, to see if raccoon rabies is present in a region. Because of the cost of testing, surveillance testing of this kind is mostly reserved for situations where there’s a concern that raccoon rabies is spreading or where the extent of the disease is being discerned.

More Q&As to follow.

Not surprisingly, “should my dog be vaccinated against flu?” has been a very common question over the past few days. Here’s my take on vaccination of Canadian dogs, with the assumption that the recent H3N2 flu cluster in southwestern Ontario has been contained (something that is likely but is still to be determined).

Who should be vaccinated?

  • Dogs that will be travelling to areas in the US where there is canine flu activity (or more broadly, dogs that travel to the US, since canine flu is present in various regions).
  • Dogs that may have contact with dogs imported from Asia. This includes mainly dogs in rescues and kennels that are actively importing dogs, as well as dogs in households of people thinking about adopting a dog from Asia.
  • Dogs that may have contact with dogs imported (or travelling) from the US. The risk here is lower, but if dogs are coming from US shelters, in particular, it’s not a bad idea to vaccinate the dogs that will have contact with them.

When else might vaccination be useful?

The benefits of vaccination decrease as the likelihood of exposure decreases. There are a few more groups where vaccination could be considered:

  • Dogs at increased risk of exposure. This includes dogs that have frequent contact with lots of other dogs, especially dogs from a wide geographic range, such as those that travel for shows or other similar events.
  • Dogs at increased risk of serious consequences. This includes dogs with pre-existing heart disease or lung disease, potential senior dogs, and brachycephalic breeds (i.e. smushy faced dogs like bulldogs).

What about everyone else?

On one hand, it’s easy to say that the risk of exposure is very low, so vaccination is of very low utility (because it’s true). The tricky part is the fact that you never know when (and it’s probably when, not if) canine flu will revisit Canada. It takes two doses of vaccine given a couple of weeks apart for good vaccine effectiveness, so by the time a problem is identified, dogs in the immediate area may already be exposed before vaccination has time to work.

That’s an inherent problem with emerging diseases.

H3N2 canine flu could pop up in any given city tomorrow, but it also might not happen for years. At the moment, it’s hard to say that vaccination is broadly indicated in Canadian dogs, but if people are particularly worried about flu, it’s a safe vaccine and there’s no reason not to get it.

What about my dog, Merlin?

He’s pretty low risk. We live in the country and he doesn’t see other dogs at home. However, he goes into work with Heather regularly and mixes with a few other dogs there. It’s a fairly small population, but those dogs presumably regularly meet other dogs (who meet other dogs…), so if flu emerged in this area, he’d be at some degree risk. At the moment, I don’t have a plan to vaccine him against flu. (Leptospirosis is a different story. He’s getting that booster tonight.)

More information about canine influenza can be found here.

Minus 20C weather is supposed to have some benefits – at least that’s what we try to tell ourselves. (Maybe we’re just trying to justify why we haven’t migrated south.)

I’ve written about leptospirosis a few times recently, given the horrible lepto season we’ve been having. This bacterial disease isn’t new, but there have been two big differences this year: one was the number of cases, which was well beyond what we’ve ever seen here in Ontario; the other was the timing of cases. I’ve been saying, for weeks, that the lepto season has to be over soon. The bacterium is shed in urine of certain wildlife hosts and likes wet – but not frigid – environments. Yet, we’re still seeing new cases.

  • We’re currently trying to figure out why this is, but I guess the key message I have for people at this point is “vaccinate,” since avoiding exposure is tough when we really don’t understand the main exposure risks.
  • The other thing is to consider lepto in sick dogs, even this time of year. Rapid treatment is important for management of this potentially serious disease, and it’s easy to understand how it would be overlooked in late December, since it’s considered a fairly seasonal disease.

Another area we’re working on a lot is tickborne diseases. The general dogma regarding ticks is that the will begin to quest (search for a host) when the temperature hits at least 4C. That’s a distant memory around here, as it hasn’t been above -10C in a while. Yet, I got a report from a reader about a feral cat carrying engorged ticks, from an area north of here that’s snow covered and even colder than here (currently sitting at -27C). It’s been well below freezing there for a long time, and well beyond typical adult tick attachment times. So, where did this cat pick up a tick? Maybe in a warm area such as a barn? Or, is 4C not really the right threshold.  It’s probably a matter of some ticks finding warmer microenvironments and cats seeking out those same warmer (or less cold) spots.

  • Regardless, this reinforces the message we’ve been saying: even in many cold climates, tick exposure is a 12-month-a-year risk. Even using the 4C threshold, it’s not unusual to get a few few days of 4C weather in the middle or winter around here. If the exposure threshold is even lower (or irrelevant if ticks can be questing in some isolated, warmer locations during cold periods) then even that gets tossed out the window.
  • For lepto, the main message is “vaccinate and be aware.” For ticks, it’s “use tick prevention and don’t stop tick-checks.” The risk is presumably quite low in winter, but low doesn’t mean zero, and tick avoidance practices aren’t particularly hard or expensive.

I guess I need to come up with a different “on the bright side…” excuse for this weather.

1) Pick up baby raccoons and take them away

  • Raccoon litter JVGRarely does this end well. It’s illegal in many areas (including Ontario). Raccoons don’t do well long-term in households for various reasons (their curious and destructive nature being a big one). And, they are potential sources of a number of zoonotic diseases (rabies being a big one but not the only concern).

2) Take them to a bar

  • This could be simplified to “take them anywhere.” The more people encounter the raccoon, the more people might be exposed to the pathogens it carries.

Seems like common sense, and yet people picking up cute raccoon kits and taking them somewhere (though not necessarily a bar) seems to happen all the time. A recent incident in Pendletown, NY, highlights the issues. A woman picked up a baby raccoon from a litter of 13 and took it to Mr. Quiggley’s Dead Dog Saloon, where it interacted with multiple people.  Because raccoons are rabies reservoirs, the raccoon had to be euthanized for testing. The rest of the litter was also tracked down and euthanized for testing, apparently, but that doesn’t make a lot of sense to me. If the raccoon to which people were exposed could be tested, that provides all the information that is needed from a rabies exposure standpoint. Maybe there was concern that other people would pick them up or maybe she put the baby back in with the litter after it’s trip to the bar and no one could tell which one it was. Regardless, the raccoons probably didn’t have rabies but the person’s actions led to their deaths.

Beyond rabies, there are a few other potential concerns:

  • Baylisascaris procyonis: The raccoon roundworm is very common, and it’s likely that eggs of this parasite were being shed in feces, or that the haircoat of the raccoon was contaminated with feces containing the eggs. The latter is the main concern because eggs that have been in the environment are the ones that can infect people. Infection in people is rare, but the parasite can cause very nasty neurological disease so it’s one to be aware of.
  • Leptospirosis: Raccoons are a host of Leptospira bacteria, which are shed in urine. Contact with urine isn’t uncommon when handling young animals, and urine that gets into cuts or the eyes, mouth or nose can result in transmission.

Hopefully not many people actually handled the critter and they washed their hands (but sometimes common sense is surprisingly uncommon).

Take home message: Leave wildlife in the wild.

Street dog2Rabies is a hot topic around here lately, with the recent identification of raccoon rabies in the province. The virus probably inadvertently arrived in Hamilton via a raccoon hitching a ride across the border. Intentional importation can also lead to introduction of rabies to different areas – I don’t mean intentionally importing rabies (people do strange things, but that’s pretty extreme), but importing dogs that are subsequently diagnosed with rabies.

The most recent edition of the CDC’s Morbidity and Mortality Weekly Reports describes a case of canine rabies that was imported into the US, and some associated issues that we keep talking about on this site.

The short version:

  • On May 30, 2015, a group of dogs (8) and cats (27) from Egypt arrived at JFK Airport in New York. They were then sent to various animal rescue groups in several states. The next day, 4 of the dogs arrived in Virgina and were distributed to 3 foster homes.
  • On June 3, one of these 4 dogs became sick, and developed signs consistent with rabies (e.g. hypersalivation, paralysis). The dog was euthanized June 5 and rabies was confirmed.
  • An investigation of human and animal contacts ensued. Typically, animals with rabies are considered potentially infectious for a period starting 10 days prior to the onset of signs of disease. It was determined that there was contact with only 1 of the other imported dogs, a puppy that shared a crate with this dog and was collected of the streets of Cairo at the same time. However, 7 other dogs had contact with the infected dog at its new home.
  • Tracing all human contacts is cases like this is a huge challenge, since it includes people in the dog’s household, other people it might have interacted with and people at various stages of the travel and importation process. 18 people ended up getting post-exposure prophylaxis.
  • The infected dog had a rabies vaccination certificate, as did 2 of the other dogs. It was subsequently determined that the certificate had been falsified ‘to avoid exclusion of the dog from entry under CDC’s current dog importation regulations.” It doesn’t say who falsified the record and what is being done to them (hopefully something, including a bill for the thousands of dollars of post-exposure prophylaxis).

An excellent closing statement from the report:

This report underscores the current difficulties in verifying any imported dog’s rabies vaccination certificate and health status. The United States also is vulnerable to an increasing risk for rabies introduction and spread from other imported domestic animals, such as cats and ferrets. Considering the public health risk posed by importation of animals for the purposes of placing them in adoptive homes in the United States, and the current oversupply of adoptable animals already in the United States, persons and organizations involved with importing pets for the purposes of adoption should consider reevaluating, and potentially redirecting, their current efforts. Globally, animal welfare stakeholders should consider focusing their efforts on supporting local organizations that provide adoptive homes, along with health care services, for street animals in their own countries. In addition, although this report focuses on imported dogs and rabies, all animals pose a risk for transmission of zoonotic diseases (e.g., brucellosis, leishmaniasis, campylobacteriosis, leptospirosis, giardiasis, and cutaneous or visceral larva migrans). Documentation of overall health status, not just rabies vaccination, is critical to minimizing the risk from importing animals carrying zoonotic diseases.

Studies that look at risk factors can be pretty variable in terms of what they tell you, the impact they have and how accurate they are.

Some findings are pretty logical, clear and indicate something that should be done.

  • Smoking is a risk factor for [insert many diseases here], so to reduce the risk of [whatever disease], stop smoking.

Others make sense but don’t necessarily lend themselves to an effective intervention.

  • Being male is a risk factor for cardiovascular disease… not much I can do about that.

Sometimes, you have to remember that a risk factor for one thing doesn’t provide a clear answer when a broader context is considered.

  • Moderate consumption of red wine can reduce the risk of various conditions, but alcohol consumption can also increase the risk of other conditions.

Sometimes, how the study is designed and performed can really affect the results.

  • If I did a large study of the general population in Guelph, I could presumably show that going to a hospital greatly increases your risk of death. Does that mean you shouldn’t go to the hospital? No, because I could presumably also show that if you have chest pain and go to a hospital, you’re more likely to live. Knowing the study population and what question is really being asked are critical.

Sometimes, something that’s found to be a risk factor isn’t really the risk factor, but it’s associated with something else that is.

Sometimes, something can be "statistically significant," but of limited consequence.

  • If doing something increases the risk significantly, but only by 0.0001%, does that mean anything?

Why do I write this? Because these are some of the things that we have to think about when assessing risk factor studies. While one Toronto radio station loves to give 10 second snippets on some new risk factor medical study, you can’t determine much about the study itself from a sound-bite (or internet post). You need to think about the details regarding how the study was done. Nevertheless, risk factor studies can provide useful information, but consider the results carefully, whether they are relevant, whether they indicate changes need to be made or whether they indicate that we need to look at the issue further.

Anyway, this rambling post was prompted by a couple of papers looking at risk factors the leptospirosis in dogs (Hennebelle et al J Am Vet Med Assoc 2013 and Raghavan et al Prev Vet Med 2012)

The first study compared dogs from northern California that had or didn’t have leptospirosis. They found a few things:

  • There were differences in geographic distribution of the lepto cases and controls. That makes sense since we know lepto varies regionally, but living in different areas might also be associated with different behaviours and contacts (e.g. wildlife contacts).
  • There was a temporal cluster, with more cases occurring between May 2003 and May 2004, compared to the rest of the 2001-2010 study period. That makes sense too since we see variation in cases within and between years.
  • These results don’t change anything, but are an indication of what work needs to be done next. Looking at why things vary geographically and temporally might be important for figuring out how to reduce the risk of disease. It also indicates regions where more efforts to educate pet owners (and veterinarians) are indicated, and where vaccination is more important.

The second study looked at dogs from Kansas and Nebraska, with and without leptospirosis. They also found a few risk factors.

  • Lepto was more common in houses lacking complete plumbing facilities. Presumably, this is a proxy for something else. Poor plumbing doesn’t likely result in lepto in dogs. Rather, it presumably means that a dog living in a house with poor plumbing has some other factor that increases its risk. For example, incomplete plumbing may be more likely in lower socioeconomic (i.e. lower income) households, which might then correspond to other more direct risk factors for the dog (e.g. poorer nutrition, less veterinary care). It could also be that houses lacking complete plumbing tend to be in a different area where there’s more exposure to wildlife reservoirs. A couple of other indicators of poverty status were also significant, highlighting the potential impact of owner poverty on pet health.
  • Dogs that lived within 2500 m of a university or college, or a park, were also at increased risk. The park risk factor makes sense since they could be exposed to sites infected by wildlife reservoirs (e.g. raccoons). Living close to a university or college is tougher to figure out. Maybe it’s associated with economy, as students are typically at lower income levels. Maybe it’s because colleges and universities usually have lots of green space that might harbor wildlife.

So, these studies tell us some new information, reinforce some previous knowledge (or perceptions) and raise some new questions that we need to answer. By themselves, they won’t result in major changes in how we try to prevent lepto in dogs, but little steps is typically how science progresses.

Life with Merlin has been busy but going pretty well. There’s been no pee on the floor in the past 48 hours so we’re making progress. Speaking of pee (which, sadly, I seem to do a lot), we need to decide about leptospirosis vaccination for Merlin.

A good preventive medicine program is important for every pet. There’s no "one size fits all" version – the program needs to be tailored for every region and pet/owner combination. We have Merlin’s deworming covered. I gave him a booster vaccine the other day, which covers distemper, parvo and a couple of respiratory viruses (adenovirus type 2 and parainfluenza). Rabies vaccination will be coming soon, when he’s a bit older (at least 3 months). Now that we have the "core" components covered, we need to think about the elective aspects. One of those is vaccination against leptospirosis.

When thinking about vaccination, it’s a cost-benefit decision. The costs and benefits can be hard to accurately assess, but a few basic questions are key: Is there a risk of exposure? Is the disease of concern? Is there a safe and effective vaccine?

Is there a risk of exposure?

Leptospirosis, a potentially life-threatening infection caused by different types of Leptospira bacteria, has been called a "re-emerging" disease in many parts of North America since rates of infection have increased over the last 20 or so years.

Leptospirosis certainly occurs in dogs around here. We don’t see a lot of cases but it’s far from rare and it can be nasty.

Wildlife are the main reservoir. Infected wildlife shed the bacterium in their urine, and urine-contaminated water and wet areas are the main sources of infection. Raccoons are the biggest concern around here, and there is certainly no shortage of raccoons around my house (including in the garage sometimes). Since Merlin is a Labrador, he’s bound to spend a lot of time swimming in ponds and wallowing around in wet areas on our property… prime sites to be contaminated by pee from infected wildlife. So, there’s a reasonable chance that he’ll be exposed.

Is the disease of concern?

There’s no doubt here. While it’s uncommon, it can be nasty. Life-threatening infections can occur and kidney failure is a major problem. Treatment of lepto can be difficult and expensive.

Is there a safe and effective vaccine?

Lepto vaccines have had a bad rap. Older vaccines weren’t very effective (often not protecting against the strains that are of concern) and were associated with a high rate of adverse reactions. Those former concerns have persisted in some people despite the fact that there’s a new generation of vaccines that are much more effective and safer. The new vaccines are better designed, better tested and cover a broader range of strains. There’s quality research indicating that they work. Like any vaccine, they’re not 100% effective but they are quite good overall.

Information about adverse reactions is harder to get. Adverse event reporting is sporadic at best, but the available information doesn’t indicate that these vaccines cause a greater incidence of adverse reactions than any other vaccine. Any given vaccine can cause a problem in any given dog, but the overall risk is low.

So, don’t tell Merlin but another set of vaccines is in his future.

More from the International Conference on Equine Infectious Diseases, this time from guest blogger and bacteriologist-extraordinaire, Dr. John Prescott of the University of Guelph:

Stellar work on understanding strangles and Streptococcus equi subspecies equi was presented at the Ninth International Equine Infectious Disease conference in Lexington, Kentucky. Researchers at the Animal Health Trust in Newmarket, United Kingdom (Andrew and Carl Robinson) are working with Matthew Holden at the Sanger Centre in Cambridge to use NextGen sequencing to understand better the strangles bacterium, and the impact of the carrier state on the pathogen as it lurks in the guttural pouch. The abstracts of their work are freely available through the conference web site, http://www.eidc2012.com/.

A novel quantitative PCR (qPCR) based on two unique genes of S. equi was was described that will identify S. equi within 2 hours, with a sensitivity of 93% and specificity of over 96%. Not only is it more sensitive than culture but it also overcomes the effects of non-S. equi contaminants which can interfere with culture. Another development reported was an ELISA based on two antigens unique to S. equi that together have a similar sensitivity and specificity to the qPCR. Current thoughts are that the ELISA could be used as a serological test in screening for carriers, with the qPCR then being used on guttural pouch aspirates to confirm the carrier state, which would then be treated.

The strangles (equi) subspecies of S. equi has been thought to be genetically and immunologically identical, but sequencing the M protein SeM gene has shown that there are over 100 strains. Holden and his colleagues have used high throughput sequencing to characterize the genomes of an astonishing 240 isolates from different countries, including one strain from Canada. They have found that genomic diversity is even higher than SeM sequencing had suggested. As a result of this work, they identified a “fitter” clone (ST151) now spreading through the UK population at the expense of an older clone (ST179).

Most interestingly, they have identified the genetic changes occurring as outbreak strains adapt to their different life in the guttural pouch, which is where the organism hangs out in carrier horses. The adaptation involves discarding some genes, stopping the expression of others, but also duplicating others. According to Holden, a Sanger Centre genome veteran, the S. equi genome is more dynamic than any of the other pathogens with which he has worked. The big question is of course the impact of this adaptation on virulence, and the extent and speed with which these genetic adaptations can be reversed if and when the “carrier“ strains revert to cause acute strangles. There is a horrible suspicion that some may be able to borrow back the deleted genes from other S. equi strains in the guttural pouch.

Because of both its species- and niche-adaptation, strangles has all the characteristics of a bacterial infection that can be eradicated. The superb work being done at the Animal Health Trust, all based on genomics, is drawing the noose ever tighter around this ancient scourge of the horse.

– John Prescott, Department of Pathobiology, University of Guelph


Earlier this year, a troop of Boy Scouts in the US beat off a rabid beaver that was attacking their leader (I wonder if there’s a badge for that). Boy Scouts and infectious diseases are in the news again, but not with as happy a story.

In the recent incident reported on ProMED, ten Boy Scouts that attended a camp on the banks of the Semois River in Belgium developed leptospirosis – a potentially severe bacterial infection caused by Leptospira bacteria. The bacteria are shed in the urine of a variety of animal species, and people can become infected through contact with contaminated water or animals. The boys reported having played with a rat, which was likely actually a muskrat, based on the description of its size.

Three of the boys were hospitalized.  Hopefully all are on the way to recovering.

This is yet another reminder that wildlife should be left alone. It’s possible the boys were infected from the environment, but handling a muskrat (which was presumably sick if they were able to get that close to it) certainly increases the risk of exposure to a variety of infectious diseases.

Image of a North American muskrat (photo credit: Linda Tanner)(click image for source)

Veterinarians at Michigan State University’s College of Veterinary Medicine are warning of an upswing in leptospirosis in dogs in the Detroit area. More than 20 cases of leptospirosis have been reported in dogs in the Detroit area, and it’s likely that many more unreported cases have occurred. Leptospirosis, a bacterial infection, can cause very serious disease, including potentially fatal renal failure. It can be vague and hard to diagnosis if people aren’t thinking about the disease. The most commonly identified problem is kidney disease, and early diagnosis and treatment is critical for successful treatment.

The Leptospira bacterium can survive well in the environment, particularly in moist conditions, and dogs are often exposed through wet environmental areas that have been contaminated with leptospires from the urine of infected wildlife. The strain that has predominated in the latest Michigan cases is Leptospira Icterohemorrhagiae, a type most often associated with rats.

Prevention of leptospirosis involves avoiding exposure to the bacterium as much as possible (largely through avoiding contact with wet areas where lepto cases have been identified) and vaccination. Vaccines are available for dogs and they can reduce the incidence and severity of disease caused by four different lepto types, including Icterohemorrhagiae.  Vaccination should be considered in dogs in regions where lepto cases are identified and in dogs at increased risk of exposure based on lifestyle and travel.

(click image for source)