In human medicine, a needlestick is a big deal. That’s not surprising because of concerns about transmission of bloodborne pathogens like hepatitis B and HIV.

In contrast, in veterinary medicine needlesticks are (unfortunately) largely considered “regular” events that aren’t really a big deal.  Most of the time perhaps they’re not. They hurt, but serious consequences are rare.  However, “rare” is not the same as “non-existent” – and if you’re the one that gets the “rare” complication, then it’s a very big deal to you.

While most needlesticks associated with animals and veterinary procedures/medications just hurt, sometimes bad things happen, such as:

  • Infection from bacteria from the patient’s skin or the person’s own skin (especially if the needlestick involves a joint, tendon sheath or other sensitive structure)
  • Allergic reaction to medication on or in the needle
  • Known effects of the drug  on or in the needle (e.g. exposure to a sedative)
  • Adverse effects of the drug in people (e.g. people have died from inadvertent injection of the cattle antibiotic tilmicosin)

A recent case report in Clinical Infectious Diseases (Amoroso et al. 2020) describes another potential issue: transmission of a patient’s infection to a veterinarian.  This same scenario, involving the same pathogen, has been previously described (Ramsey JAVMA 1994). I mention this risk when I talk about needlestick issues, but this new case report is a good reminder.  Here’s the summary:

  • The veterinarian was performing a fine needle aspirate on a mass from a dog that was ultimately diagnosed with blastomycosis (a fungal infection caused by Blastomyces dermatitidis). This procedure involves sticking a needle into the mass to try to extract some cells for testing. In the process, she stuck her finger by accident. Three weeks later, she went to her doctor because the finger was swollen and painful. She had surgery to open up the infected finger joint and testing revealed Blastomyces dermatitidis. Presumably the vet had informed her physician about the dog’s diagnosis, but surprisingly, that’s not always the case in occupational or animal-associated exposures. Sometimes important information like this isn’t passed on. The veterinarian was treated with an antifungal and fortunately the infection resolved.

I try not to be alarmist when it comes to emerging diseases, but we can’t be dismissive either. There wasn’t much attention paid to needlesticks in human medicine until people started to get sick (and die) from the consequences (especially infections). You don’t know about an emerging disease until it’s emerged. Infection control is inherently reactionary. Actions are most often taken in response to a known problem, rather than a potential issue.

One of my mantras is “don’t be a case report.” I can’t completely prevent that, but by reducing the risk of a needlestick injury, I can reduce the risk of me being the “first reported case of ______ acquired by a needlestick from an animal.”

Unlike many infection control activities, needlestick injury risk reduction is straightforward and doesn’t really take much time or effort. It includes things like:

  • Never recap a needle
  • Never leave an uncapped needle on a surface
  • Never pass an uncapped needle to someone else
  • Always dispose of needles immediately into an approved sharps container
  • Never leave needles in lab coats or other laundry (yes, this still happens and people get stuck… and understandably pissed off)
  • Consider using safety devices that include sharps injury protection mechanisms like retracting needles or sheathes that are pushed over the needle

I’ve done all of the “never” list above, except maybe the laundry one. As a busy medicine resident, in particular, I was pretty cavalier and got stuck many times, usually because we were rushing with an emergency, but also because I gave it little thought. There was never a culture of needlestick injury prevention, or even event reporting (even when a patient broke a bunch of my ribs).

Like a lot of things in infection control, the science is easy. Behaviour change and culture change are the bigger challenges.  Sometimes taking a few seconds of time and having some basic awareness is all that’s needed.

Image below from Amoroso et al. Clin Infect Dis 2020

I keep saying spring is approaching and I keep getting disappointed by the cold weather.  But it’s going to happen soon, so we’ve been gearing up for tick season. There are a few new initiatives underway for tracking ticks and tickborne diseases in Canadian dogs and cats. Check out the recent post at for more information.

Here’s a post by Dr. Katie Clow from our sister site,
Today, we received our 400th tick submission (actually, 401 to be exact). Does that sound like a large or a small number?
Although there’s no real answer to that question, to me it seems like a pretty small number. At this time last year, when the Pet Tick Tracker ran through the Worms & Germs Blog, over 1400 submissions had been received.
So, what might be going on this year? Here are some thoughts…
1. We’re getting bored with ticks and no longer reporting
This is a common problem with passive surveillance in areas where tick populations are well-established and the burden is high. Citizens get so used to seeing ticks and tire of submitting the same findings (understandably!). Although this may be occurring in some areas, we are still in a time when tick populations are changing rapidly, with ongoing expansion, so I don’t think this is the primary explanation. (**But, I’m still going to use this as an opportunity to encourage ongoing submissions, and sharing of our webpage with friends, family and colleagues!**)
2. We’re getting really good at using tick preventatives
I hope this is the reason! This means that our furry friends are protected. However, the most common tick products on the market (isoxazoline class of parasiticides) do not prevent tick bites, but kill the tick as it begins to feed. Therefore, we may still see ticks on our pets, just not for very long.
3. 2018 is a “low” tick year
Yes, this can happen, and this could be happening this year. It’s too early to really know, but other methods of surveillance have been finding ticks in lower numbers, too. Unfortunately, this does not mean that risk is decreasing. We see inter-annual fluctuations in ticks populations due to a variety of ecological factors. One hypothesis is that because it was so dry in many areas of the country, the ticks (especially blacklegged ticks) were not as active. Blacklegged ticks are highly sensitive to low humidity, so if it’s too dry, they will not be as active.
If you are finding ticks, it’s so important that you continue to submit. The more information we have, the more we can learn about tick populations in our country.
P.S. Our maps have been updated again.

A post from guest blogger Dr. Katie Clow, reproduced from our sister site

It’s summertime, and for most Canadians that means we’re taking some time off work to enjoy a little rest and relaxation. Maybe that’s a week at the cottage, or an adventure in another county. And if it’s a family trip, there’s a good chance your furry friend is coming along, too.
Not to put a damper on the situation, but in your trip planning, it’s a good idea to think about ticks and more broadly, disease risks to which your furry friend (and yourself) may be exposed when away from home.
Over the last few months, we’ve had several submissions of ticks from pets with international travel history. In June, we received two submissions from a dog that had been in Texas. One tick was a Gulf Coast tick (Amblyomma maculatum) and the other a brown dog tick (Rhipicephalus sanguineus). More recently, we had a submission from a dog that was in Myrtle Beach. Thanks to a nice photo that accompanied the submission, this tick could be identified as a Gulf Coast tick too.
Gulf coast ticks and brown dog ticks are rarely identified on dogs in Canada, and when they are, it is almost exclusively due to travel. In the case of the Gulf Coast tick, the risk posed is almost exclusively to the individual animal, as it is very unlikely for the tick to survive for a prolonged time in the environment. The brown dog tick on the other hand is a particularly nasty tick – it can survive and reproduce happily in a home or kennel and cause massive infestations even indoors!
With foreign species of ticks come different pathogen risks (and by pathogens, we mean bacteria, viruses and parasites). But it’s also important to remember that species of ticks that we commonly see here but have been picked up in a different county can transmit different pathogens. Take the example of the American dog tick, Dermacentor variabilis. We see this tick all the time in eastern Canada, but rarely do our resident American dog ticks carry pathogens (right now, anyways). The situation is completely different if you encounter this tick in the southern USA, where it transmits several pathogens, including Rickettsia rickettsii, the bacterium that causes Rocky Mountain Spotted Fever.
This story extends far beyond ticks and makes us think about other potential disease risks that our pets can encounter in different areas of the country, and the world.
So, what does this all mean if you want to travel with your furry friend? It’s as simple as being aware of the risks and taking the proper precautions (and in high-risk situations, leaving them at home).
It’s a smart idea to visit your veterinarian before traveling with your pet, whether this be local travel to the cottage or an international trip. That way you can make sure the preventative health care plan for your pet is appropriate. Parasite prevention and vaccinations are targeted towards the risks your pet may be exposed to on a regular basis, and adjustments can be made if your pet is going to be exposed to new health risks.
Happy travels.

After a particularly miserable spring here (to put it mildly), it’s finally warming up, and the snow’s almost gone. That’s the good news. The bad news is that ticks are also going to start coming out and looking for food – that means looking for animals (including us).

I assume there will be lots of tick posts on this site over the next few months. That’s for good reason, since tickborne diseases are an important topic and the risk of tickborne disease exposure continues to increase in many areas.

To help increase tick awareness and surveillance, we’ve launched a companion site: This website will (surprise, surprise) focus on ticks, and has a re-tooled version of our PetTickTracker that was originally launched in May 2017. The new tick tracker has an easy  online submission process and we’ll hopefully soon have more real-time plotting of tick tracker results on the map.  You can also still access last year’s PetTickTracker maps by clicking here.

Lone-Star-tick-associated meat allergy is an interesting phenomenon in people that is getting a lot of attention, especially as these ticks (like others) are expanding their range.  The condition itself is one of those odd-ball quirks of nature that you’d never expect.

The basic story goes like this:

  • galactose-alpha-1,3-galactose (alpha-gal) is a carbohydrate that’s part of cell membranes in most mammals, except humans, apes and Old World monkeys. It’s also found in the saliva of the Lone Star tick (Amblyomma americanum, pictured above)
  • Because it’s a “foreign” substance to humans, if their immune system encounters it, it may create antibodies against the carbohydrate. This can happen with a Lone Star tick bite, as the body reacts to tick saliva.  Although it’s rare, this can lead to allergic reactions when the body encounters alpha-gal again.
  • Since alpha-gal is present in red meat (but not poultry or seafood), ingestion of meat in people with a lot of antibodies against alpha-gal can result in an allergic reaction. This usually occurs 3-8 hours after eating and is often manifested as development of itching, hives, vomiting and diarrhea. Anaphylaxis is possible but uncommon.

Lone Star ticks can bite dogs and there’s been some talk about meat allergy as a reason for tick prevention in dogs. But, what’s the story?

  • We don’t really know, but I have a hard time seeing any risk of dogs developing meat allergy secondary to Lone Star tick bites.
  • Since dogs are mammals of the non-human/ape/monkey variety, the are already full of alpha-gal. It’s not a good survival technique for a host to create antibodies that attack itself, so a Lone Star tick bite that transferred alpha-gal would just be adding a minute amount to a dog that’s already full of the carbohydrate. There shouldn’t be any risk of antibody development or food allergy.

There are a lot of good reasons for tick prevention in dogs, but I can’t see acquired meat allergy being one of them.

The latest Worms & Germs infosheet, all about Lyme disease and ticks, is now available on the Resources – Pets page.  Although it’s getting colder and occasionally snowy up in Ontario, there are lots of parts of North America where ticks are active all year round.  It’s particularly important for any "snowbirds" who may travel south with their pets over the winter to be aware of the potential for exposure to ticks and the diseases they transmit (not just Lyme disease!), and to make sure their pets (as well as they themselves) are properly protected.  (The same goes for exposure to mosquitoes, which can transmit (among other things) heartworm.)

Remember that dogs (nor any other mammal for that matter) cannot transmit Borrelia burgorferi, the bacterium that causes Lyme disease, to people; however, this is a good example of a "one health" disease that clearly affects both people and animals.  Finding the disease in one species is an indication that the other is at risk as well, when there is exposure to a common source (i.e. the ticks).

Thanks to University of Guelph professor and parasitologist Dr. Andrew Perigrine for his input on the infosheet as well.

Image: A female blacklegged tick, Ixodes scapularis, engorged with a host blood meal. (Source: CDC Public Health Image Library 15993)

Something I often discuss when doing infection control talks is needlestick injuries. The contrast between the approach to needlestick injuries (and blood exposure in general) in veterinary and human medicine is pretty astounding. In humans, there are strong educational campaigns, careful reporting, testing and treatment protocols, and increasing use of "safety engineered sharps devices" like retractable or guarded needles. In veterinary medicine, getting stuck with a needle is often considered "part of the job" and "no big deal". A study we did of veterinary technicians a few years ago found that 74% of techs had suffered a needlestick injury in the past year (Weese & Faires, Canadian Veterinary Journal 2009). I’ve had many such injuries during my career, pretty much all before I started to focus on infection control, and I honestly didn’t put much though into them (beyond ”oh crap, that hurt!”).

There are some valid reasons for the differences between human and veterinary medicine when it comes to needlestick injury prevention, not the least of which is the risk of HIV and hepatitis B virus transmission. In some ways, getting people to pay attention to needlesticks in veterinary medicine is tough because we don’t have viruses such as these in our patients. Needlesticks can cause pain, significant trauma and rarely severe (including fatal) problems (e.g. from drug reactions or infections), but the vast majority are rather inconsequential. However, a line that I frequently use is: “We don’t have an analogue of HIV or hepatitis B… at the moment. New diseases continue to emerge and you never want to be the index case.”

Is this really a risk? Well, yes. Beyond some new disease that could emerge and be a serious problem, we also have new issues being identified from bugs that we’ve known about for a while. Recent concern has been expressed about transmission of Bartonella species. This is a strange group of bacteria that are commonly found in cats and dogs. Bartonella henselae is the cause of cat scratch disease, a well-known problem, but Bartonella are attracting a lot more attention these days because they are being implicated in a range of often vague human diseases. Bartonella can be found in the blood of healthy cats (and to a lesser degree dogs), raising questions about whether a needlestick could result in transmission of these bacteria to people.

Two case reports highlight these concerns.

The first one (Lin et al, Vector Borne and Zoonotic Diseases 2011) tells the story of a veterinarian who developed a fever of unknown origin and back pain. Ultimately, he was diagnosed with Bartonella henselae infection which they speculated may have been transmitted following a needlestick injury. The needlestick link is weak here though. As a veterinarian, there are lots of other opportunities to be exposed to Bartonella henselae. It’s not uncommonly present in the blood of healthy cats and the main route of exposure is through fleas. Fleas feed on the cat, pick up the bacterium, then shed it in their feces. Cat scratches are a common route of transmission as the contaminated flea feces may be driven into the body. The veterinarian in the report didn’t recall having been bitten or scratched recently, but recall bias is an issue since scratches are common and often forgotten if not severe. Flea exposure wasn’t queried. Also, the needle with which he was stuck was a clean needle that had not been used yet. It still could have been the source of infection if it acted like a scratch, driving infected flea dirt on his skin into the wound, but I don’t think this report is very strong.

The second article (Oliveira et al, Journal of Veterinary Internal Medicine 2010) describes infection by a different Bartonella speces, B. vinsonii berkhoffii, also in a veterinarian. The person was taking an aspirate from a mass with a needle and syringe and was poked in the finger as the dog was struggling. Five days after the needlestick, the person was still healthy. A blood sample was taken from the person and Bartonella was not found. However, by day 34 after the incident, the veterinarian reported having had frequent headaches for the past week, fatigue and some intermittent numbness in one arm. Bartonella vinsonii berkhoffii was detected in the person’s blood at that time. There was also an increase in anti-Bartonella antibodies between the two blood samples, which supports an active infection. The bacterium was not found in the tumour aspirate, but as a dog-associated bacterium and one that is rarely identified in people, and with the timing of exposure and disease, it’s quite suggestive that the needlestick was the source.

These may just be two reports, but they may just be the tip of the iceberg, because disease caused by Bartonella infections is often vague and probably routinely gets missed. There’s also increasing evidence of wide-ranging types of infection that may be overlooked, so people (and particularly veterinary staff) need to be aware and pay attention to the potential risk.

Needlestick injuries shouldn’t be considered part of the job. There are risks, but a little common sense goes a long way.

Information sheets on both cat scratch disease and needlestick injuries (and how to avoid them) are available on the Worms & Germs Resources – Pets page. 


As we (finally) get nice weather here, a rash of questions about ticks usually follows.  Ticks are very common in some areas, and a short walk in the woods can result in exposure. Ticks themselves aren’t the concern. The problem is infectious diseases that ticks can transmit, including Lyme disease. The risk and types of diseases of concern vary geographically. (In Ontario, exposure to ticks that can transmit Lyme disease is most common in Point Pelee, Rondeau, Long Point, Turkey Point and the Thousand Islands area). There are a number of ticks that may feed on people and pets, but only a few that transmit infections. Your veterinarian, physician and/or public health departments should be able to tell you what diseases are of concern in your area.

Regardless of where you live, if you and your pet might encounter ticks, you should know how to remove them. Prompt removal is the key. Most tickborne diseases aren’t transmitted immediately. Rather, the tick must be attached for a period of time for infection to occur. Therefore, close inspection of your pet (and yourself) for ticks after spending time outside, is important.

The following tick removal tips come from the Centers for Disease Control and Prevention (CDC).

  • Remove a tick as soon as you see it.
  • Use fine-tipped tweezers to firmly grasp the tick very close to your skin. With a steady motion, pull the tick away from your skin. Then clean your skin with soap and warm water.
  • Avoid crushing the tick’s body.
  • Do not be alarmed if the tick’s mouthparts remain in the skin. Once the mouthparts are removed from the rest of the tick, it can no longer transmit Lyme disease bacteria.
  • If you accidentally crush the tick, clean your skin with soap and warm water or alcohol.

Tick removal devices are also available and can be used in place of tweezers. If you use one, make sure the device does not squeeze the tick’s body as you remove it.

If a large number ticks are present on your pet, you should contact your veterinarian for assistance. Typically, a product that kills ticks will be applied to your pet.

There are various anecdotal recommendations that should be avoided, including burning the tick off with a match and covering the tick with substances such as gasoline, petroleum jelly or nail polish.