Maureen Anderson
Maureen Anderson is currently a post-doctoral fellow in the Department of Pathobiology at the University of Guelph. She grew up in Montreal, Quebec. In 1998 she moved to Guelph, Ontario where she completed her veterinary degree in 2003. Following a year and a half in mixed animal private practice in Listowel, Ontario, she returned to the University of Guelph for graduate studies in infectious disease and a residency in Large Animal Internal Medicine. She completed her thesis on methicillin-resistant Staphylococcus aureus (MRSA) in horses in December 2007, and became board certified with the American College of Veterinary Internal Medicine (ACVIM) in the spring of 2008. She has two cats named Bonnie and Clyde.
Check out the new information sheets about Clostridium difficile now available on the Resources page!
Cat bites - Why it's not "just a scratch"
Even the most well-natured, lovable cat has the potential to bite. Particularly if an animal is frightened or in pain, it may lash out with teeth and claws, even at its most trusted human companion. Many of us are used to sustaining small cuts and wounds in everyday life, and at times it hardly seems worthwhile to trouble a physician to look at a little cat bite. But 20-50% of cat bites become infected, compared to 4-20% of dog bites. The bacteria responsible are most often combinations of Pasteurella spp., Staphylococcus spp., Streptococcus spp. and others. In some cases, particularly when Pasteurella multocida is involved, the infection can develop very rapidly (within hours) and may become very serious, or even spread to the bloodstream. Cat scratch disease (Bartonella henselae infection), despite the name, can also be transmitted by cat bites. Cat bites can be very deep, even though they look very small at the level of the skin, which may lead to infection of things like joints and tendons under the skin, which are more serious.
You should see a doctor about any cat bite on a hand, over a joint, over a tendon sheath (such as the wrist or ankle), over a prosthesis or implant, in the genital area, or that causes a deep tear. You should also see a doctor for any bite if you happen to have a weakened immune system for any reason (e.g. HIV/AIDS, cancer or transplant patients).
The best way to prevent infection is to prevent the cat from biting you in the first place!
- Use common sense – know how to handle a cat properly so that it is not frightened or uncomfortable. If a cat growls at you or tries to get away, let it go!
- Don’t let cats play with your hands, feet or hair. Use a nice cat toy instead.
- Don’t approach strange cats, especially strays. If you are bitten by a cat that may not have been vaccinated for rabies, it is very important to report the incident to you local public health department and your doctor, as you may need to receive rabies post-exposure prophylaxis (PEP).
Tularemia Trouble
A case of pneumonic tularemia was recently reported in New York City.
Tularemia is a disease caused by the bacterium Francisella tularensis. It causes different signs of illness depending on how the bacteria enter the body. If the bacteria are inhaled, it tends to cause pneumonia (pneumonic tularemia). If the bacteria get in through a break in the skin, infection may cause the local lymph nodes (glands) to become very swollen, and in some cases the skin itself may become infected resulting in the formation of large sores (ulcers). Infection can also cause sores in the mouth and diarrhea. The earliest, most common signs are things like fever, headache, chills, sore muscles, and sore throat which often come on very abruptly. The infection can be treated with antibiotics, but it is important to see a doctor and start treatment as soon as possible.
Tularemia is also sometimes called "rabbit fever," because the bacteria are often carried by animals such as rabbits and hares. Rodents (including beavers, rats, mice, squirrels etc.) can also carry F. tularensis, and occasionally so can cats and dogs. Some biting insects like deerflies and certain species of ticks can carry the bacteria and transmit it when they bite. Francisella tularensis can also survive in water and soil for a long time. People can become infected by being bitten by an infected insect, handling an infected animal (dead or alive), or coming into contact with feces from an infected animal. Occasionally a person may inhale the bacteria if it is in the air, as may happen with disturbed, dusty, contaminated soil.
More information on tularemia can be found on the CDC's tularemia website.
Things you can do to avoid tularemia:
Avoid touching or handling wildlife (dead or alive), especially rabbits and rodents.
Don't let your pet touch or eat dead animals.
Always wash your hands if you have been working outside in the dirt/soil.
Wear insect repellent containing DEET (visit the Health Canada website for more safety tips)
Make sure you only wash food with and drink water that has been properly treated.
One of the reasons tularemia is such a big deal is it is very infectious - as few a ten bacteria can be enough to make even a healthy person sick! But it is still quite uncommon in North America - about 100-200 cases are reported in people in the USA every year. Between 2002-2004 there were 34 cases reported in Canada, most of which occurred in Quebec and in adults. However, infection can be fatal in a very small number of cases, especially if proper treatment is not given as soon as possible.
Toxoplasmosis - Why Your Cat Shouldn't Get the Blame or the Boot
Toxoplasma gondii is one of the most widespread zoonotic pathogens in the world. Toxoplasma is a protozoal parasite that can infect almost any warm-blooded animal, including humans. In most people and animals, infection doesn’t cause any illness at all, and after the initial infection, the body usually produces strong immunity which protects it from subsequent Toxoplasma infection. Problems arise when infection occurs in a person with a weakened immune system. For example, toxoplasmosis (i.e. illness due to Toxoplasma) has been a major problem in HIV/AIDS patients, although better HIV treatments have decrased the incidence of the disease in this group in recent years. Toxoplasma can also cause problems when a woman is infected for the first time, before her body has developed immunity to the parasite, while she is pregnant. In these cases, the parasite can infect the fetus. This may result in birth defects or loss of the pregnancy altogether.
Our friendly feline companions have the unfortunate distinction of being what is called the “definitive host” of Toxoplasma. This means that even though the parasite can infect many species of animals, cats are the only species that shed the parasite “eggs” (which are called oocysts in this case) in their stool after they’re infected. But what most people don’t realize is that the number of cats that are shedding oocysts at any one time is very small – usually less than 1 in 100. And after the first time a cat is infected, it usually doesn’t shed oocysts again, and if it does it sheds them in very low numbers.
Depending on individual lifestyle and eating habits, a person is just as likely or more likely to be exposed to Toxoplasma from working in the garden or eating undercooked meat (particularly free-range pork or wild game). People who are pregnant or who have a weakened immune system do NOT need to get rid of their cats because of Toxoplasma, but they DO need to take steps to avoid exposure to Toxoplasma from all sources. This includes avoiding contact with cat stool and kitty litter by asking someone else to clean their cat’s litter box for them if possible, or wearing rubber gloves and being very careful to wash their hand very well afterwards if they need to clean the box themselves. Here are a few more tips that can help reduce their risk of exposure to Toxoplasma:
- Clean your cat’s litter box every day. The oocysts usually take about 24 hours to become infective once they’ve been passed in your cat’s stool, so daily cleaning helps remove them before they reach this stage.
- Always wash your hands with soap and water after cleaning your cat’s litter box, after working in the garden or in any soil, and after handling raw meat.
- Cook all meat, especially pork, lamb, mutton and wild game, to an internal temperature of 67ºC/153ºF or higher.
- Keep sandboxes covered so outdoor cats don’t contaminate them with stool.
- Keep your cat indoors. Outdoor cats are more likely to be exposed to Toxoplasma and shed oocysts in their stool.
Fido fights allergies
Although allergies are not an infectious disease that can be transmitted from animals to people, many a household is declared a “pet-free zone” because one or more of the people who live there is allergic to our furry friends. But for many others, the itchy, watery eyes, sniffles and constant need for antihistamines are a small price to pay for the companionship of their beloved pets.
It's estimated that as many as 15% of people are allergic to pets such as dogs and cats. But a new study from Germany has come out that shows that having Fido around when you're very young may actually help decrease the likelihood that you'll develop allergies later on. In the study, infants who lived in a house with a dog were less likely to develop allergies to things in the air such as pollen and dust by the time they were six years old, compared to children that did not live with a dog. This may be because having a dog around exposes an infant to certain allergens that help “train” the immune system from an early age not to over-react and therefore cause allergies. There was no significant difference in the likelihood that a child would develop allergies specifically to dogs between the two groups.
The American Kennel Club lists several dog breeds that tend to cause fewer problems for people with allergies. But in truth there is no such thing as an non-allergenic dog (or cat) – it’s a matter of degree, and also depends very much on an individual person’s immune system, and your symptoms may also depend on how many other allergens you are exposed to at the same time. Most adults cannot be “cured” or their allergies, but if you have allergies and suspect that your pet may be contributing to them, talk to your doctor about things you can do to try to reduce your symptoms to a more liveable level.
Camping with canines - tick tick not!
The warm weather is just about here, and that means the start of camping season. Lots of people love to spend time in the great outdoors during the summer, whether it’s at a summer cottage on the lake, trailer camping in a park with electricity and running water, or roughing it in a tent in the peace and solitude of a more remote wooded location. And many people bring along their faithful companions – their dogs – who enjoy the experience just as much, if not more, than we do.
But there are also dangers lurking in the forests – microscopic dangers carried by tiny insects and other bugs. Ticks in particular are problematic. Certain ticks can carry a number of diseases that can make dogs sick, including Lyme disease (caused by Borrelia burgdorferi) and Rocky Mountain Spotted Fever (RMSF)(caused by Rickettsia rickettsii ). Both Lyme disease and RMSF are more common in certain areas where the tick species that carry them are present. You can NOT catch these diseases from your dog, but both you and your dog can be infected by the ticks that carry them. People can also be exposed to these pathogens by accidentally crushing an infected tick while trying to remove it from their dog. Ticks must be removed very carefully to ensure that the entire tick is removed, including the head and mouth pieces, without crushing it. If you're not sure how, contact your veterinarian. Also, the sooner the tick is removed, the less likely it is to transmit certain diseases, so be sure to check your dog thoroughly for ticks when you come back from a walk in the bush.
The Minnesota Department of Health recently reported that the number of cases of (human) Lyme disease increased in that state in 2007. This could be because of spreading tick populations, more people participating in activities in tick-inhabited areas, or increasing awareness and diagnosis of the disease by physicians.
If you and your canine companion will be spending time in some of the wilder and woodier parts of the great outdoors, talk to your veterinarian about what you can do to protect your dog. There are vaccines available for Lyme disease and the bacterial infection leptospirosis (which is also transmissible to people). Flea and tick preventatives are also very important, and many of today’s products are very effective. People should always wear insect repellent when camping or hiking in the woods. Visit the Health Canada website for safety tips on using personal insect repellents. All dogs should be vaccinated for rabies, whether they go camping in the backwoods or they’re house-bound city-slickers.
Horses and MRSA
Many people in the horse world have heard the hype about methicillin-resistant Staphylococcus aureus (MRSA) in horses. MRSA can cause infection in horses, just like it can in people, dogs, cats and many other animals. It’s usually what we call an “opportunistic” pathogen, meaning it usually takes advantage of a person or an animal that is already sick or injured, like someone who’s in the hospital and has just had surgery. And because MRSA is resistant to many different antibiotics, the infection can be difficult to treat. The big concern with MRSA in recent years is that infections are now sometimes occurring in people who aren’t sick, and who don’t have wounds or incisions, which is where MRSA usually likes to move in. It’s very important to find out from the start if an infection is being caused by MRSA, so that it can be prevented from spreading to other people and animals, and so that it can (if necessary) be treated with the right kind of antibiotic.
Horses are a bit of a special case when it comes to animals and MRSA. When researchers look at the DNA of MRSA from a dog or a cat, it usually turns out to be one of the common human MRSA strains (usually called a “clone”) from the same area. This means that the dog or cat probably picked up the MRSA from a person somewhere. When researchers look at the DNA of MRSA from horses, however, they often find a different clone, which seems to be more common in horses and people who work with horses than in people in general. A very similar situation has also been discovered in pigs. The worry is that this “horse MRSA clone” can survive in and be transmitted between horses better than the human MRSA clones. That means that in order to control MRSA, just controlling it in the people won't do the trick - we need to take steps to stop the spread of MRSA in horses specifically as well.
Here are some key points to help reduce the risk of your horse (and you!) getting MRSA:
- Always wash your hands with soap and water (or use an alcohol-based hand sanitizer) after handling a horse, and before handling another horse.
- This is especially important if you have touched a horse’s nose, or any cuts or wounds that the horse may have.
- Don’t go down the row of stalls in the barn and pet every horse on the nose! They love the attention, but this is a great way to spread MRSA if it’s there!
- New horses coming into the barn, or animals coming back from a hospital, should be kept separate from all the other animals and only dealt with after all the other horses, for 3-4 weeks.
- This is an important measure for controlling many infectious diseases, not just MRSA.
- If your horse has a cut that looks infected, cover it with a bandage of some kind and contact your veterinarian. Your veterinarian can culture the wound to determine if it is an MRSA infection.
The Great Indoors - Keeping Kitty Content
Many a cat owner still believes that a cat’s natural habitat is outside in the great outdoors, where they can hunt mice and birds, chase insects and climb trees. Even after being domesticated and bred in captivity for hundreds and hundreds of years, house cats of all breeds still have those basic feline instincts – they love to prowl, hunt, stalk, pounce, and some delight in tearing their toys limb from limb. But from a health and infectious disease control standpoint, the great indoors is a far better place for your feline friend.
- A cat that goes outside, especially one that hunts, is more likely to pick up bacteria like Salmonella, or parasites like Toxoplasma and intestinal worms, which can potentially be transmitted to people, whether or not the cat gets sick. Outdoor cats are also more likely to come home with parasites like fleas which, in addition to being a major nuisance to you and your pet, can also transmit tapeworms and may contribute to the transmission of cat scratch disease (bartonellosis).
- Cats that live exclusively indoors are also not at risk of contracting two very important viruses, namely feline immunodeficiency virus (FIV, which is the cat equivalent of the human HIV/AIDS virus) and feline leukemia virus (FeLV, which is sometimes also called Fe-Leuk). These viruses are transmitted by direct cat-to-cat contact, particularly during cat fights. They cannot be transmitted to people, but they can make your cat very sick and prone to other infections, some of which may be zoonotic.
- It’s also easier to keep track of your cat’s health if it doesn’t go outside. Changes in your cat’s drinking and litter box habits, which can be important indicators of various health problems, can be detected much faster if your cat isn’t finding alternate sources of water or places to do its “business” outside.
- And there are still other benefits to keeping your cat indoors, including not having to worry about your kitty being hit by a car, not having to treat fight wounds and cat bite abscesses, and not having your feline friend bringing little “presents” into the house, like dead (or not so dead) rodents and birds.
See our Resources page for more information on zoonotic diseases in cats.
Not-so-likable licks
Sometimes when you fall and scrape your knee, or cut your hand, your favourite furry friend, in an act of unhindered devotion, will do to you what they would do to their own cuts and scrapes – they will try to lick it clean. The story that is often cited is the one about dogs and cats having enzymes in their saliva that help clean the wound. While it can’t be denied that there are various enzymes in the slobber, when you consider what else is in your little friend’s mouth, you’d be better to pass on their touching offer to help you clean up your cuts.
First of all, think about where that mouth has been, and what’s been in it! Does your cat hunt mice and birds around your house? Does your dog have a habit of eating unidentifiable bits of garbage or poop when out on walks? Or maybe your dog, like so many, enjoys a snack from the cat’s litter box every once in a while. You probably want to keep things like garbage and poop out of your cuts, and if your pet’s mouth has been there, it shouldn’t be near your wounds either.
Even dogs and cats that don’t have any distasteful eating habits have millions of bacteria of many different kinds in their mouths. Most of the time the bacteria don’t cause a problem, and the “good” bacteria help to keep the “bad” bacteria in check. But if the “bad” bacteria are put somewhere the body’s defense systems have already been breached – like an area of broken skin – those same bacteria suddenly have a prime opportunity to move in and start multiplying in their new home. Some bacteria like Pasteurella multocida can cause very serious infections in situations like this. This species of bacteria is one of the primary culprits in bite wound infections, which are especially common with cat bites.
So why do animals lick their wounds in nature? Well, “dirty” is in fact a relative term. An animal can use its tongue to get the worst of the dirt and debris out of a wound, and the wound will be cleaner. But compared to how clean you can make a cut by even just washing it with a lot of water and some soap, and maybe a little disinfectant, a lick from a cat or a dog is counterproductive to say the least. So the next time you have a boo-boo that Fifi or Fido wants to kiss better, say thanks, but no thanks.
Information Sheets for Pet Owners
INFORMATION SHEETS specifically for VETERINARIANS and for KIDS are also available on the Worms & Germs RESOURCES page!
Click on the highlighted topics below for information sheets. Topics that are not highlighted are in development and coming soon. Sheets for other animal species and diseases are also under development and will be added when they are available. 
| Animals | Diseases | Other |
| Dogs | Rabies | Litter Boxes |
| Cats | Giardia | Sandboxes |
| Turtles | Toxoplasma | Cat Bites |
| Hamsters | Leptospira | |
| Clostridium difficile | ||
| Cryptosporidium | ||
| MRSA | ||
| Campylobacter | ||
| Salmonella | ||
Please Remember:
- Your veterinarian and physician are your ultimate resource for information about the health of your pets or your family.
- Information provided here is accurate to the best of our knowledge, but infectious diseases can be unpredictable and these sheets are for general information purposes only.
- There can be great variation in disease risks in different geographic areas. The information provided was developed for Ontario, Canada, but most of the information is relevant for other regions as well.
