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.

My dog has MRSA... what do I do?

This is a question that I get on a regular basis. Methicillin-resistant Staphylococcus aureus (MRSA) is an antibiotic resistant bacterium that is a major cause of disease in people and is also a cause of disease in various animals species, including dogs and cats. It can cause a wide range of infections, from mild skin infections to rapidly fatal disease. Most MRSA infections in animals are treatable if managed properly and most are treated in the home (as opposed to requiring a stay at a vet clinic). Because of this, there are concerns about transmission of MRSA from infected pets to people in the household. Transmission of MRSA between people and pets (in both directions) definitely happens, although we don't really know how often this occurs.

If your pet has MRSA:

  • Talk to your veterinarian about how to handle the infection
  • Avoid contact with the infected site. If you have to touch it, use gloves and wash your hands         immediately afterwards.
  • Wash your hands regularly after contact with your pet
  • Avoid contact with your pet's face...MRSA often lives in the nose, in addition to the site of infection
  • Try to limit overall contact with your pet until the infection has resolved. Close, prolonged contact such as letting the pet sit on your lap or sleep on your bed should be avoided
  • Follow your veterinarian's instructions closely. Always complete the full course of treatment, even if your pet looks better
  • Talk to your physician if you have concerns about your health, particularly if you or someone in the household has a compromised immune system
Should I be tested?
Current recommendations are that there is no indication to test people or pets for MRSA carriage when there is an infected pet (or person) in the household. Testing might be reasonable in some circumstances where uncontrolled transmission of MRSA appears to be occurring in a household, but there does not seem to  be a reason to test with single incidents of MRSA infection.


Studies are currently underway looking at transmission of MRSA in households where pets have an MRSA infection. Better information will likely be available in the future as a result of these studies.

More information on MRSA in pets will be available soon in our Resources section.  Another good source of information is the Bella Moss Foundation, a charitable foundation dedicated to MRSA in animals.

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Horse visits hospital

Recently, a story about a man who brought a horse into a hospital to visit his father was widely reported. The horse apparently made it to the man’s room, which included a trip in an elevator. The son, who appeared intoxicated, was eventually asked to leave (and take the horse with him). Said a hospital spokesperson “We do have a pet visitation policy, but it does not include a horse”. Strangely, the horse that was brought to the hospital apparently wasn’t even the father’s horse (which supports suspicions of the son’s lack of sobriety).

There are guidelines about which animals are appropriate for hospital visits, although it shouldn’t take an expert to figure out that a horse is not an appropriate candidate. Kicks, bites, and trauma from being crushed or run over are among the most obvious concerns. Horses can also carry a variety of bacteria that are potentially dangerous, especially to people in hospitals. These include Salmonella and methicillin-resistant Staphylococcus aureus (MRSA). There also aren’t that many house-trained horses out there.

So, while I can easily see how someone in a hospital would like to see his or her horse, there’s no way this should even be considered.

Some closing thoughts
-    Would you like to ride in an elevator with a horse?
-    Would you like to be stuck in an elevator with a horse?
-    Do you think the horse was house trained?
-    Do you think any of the healthcare personnel washed their hands after touching the horse?

This isn't the first time a horse has been in hospital, and some even get invited. The picture is from a story in Veterinary Practice News that described a program where horses were brought into hospitals!

UK Chief Vet says no pets in bed

The UK’s Chief Veterinary Officer Fred Landeg recently declared that pets should not be allowed to sleep in peoples’ beds or even be allowed in the bedroom.  The reasoning behind this recommendation was the potential for transmission of bacteria such as Salmonella and Campylobacter. This was in response to a publication in the Veterinary Record describing animal-human interactions in households in the UK. It reported that 20% of participants let their dogs sleep in the bedroom and 14% let their dogs sleep in their bed.

While it is certainly true that any healthy animal (and person) can carry infectious diseases, and that prudence is reasonable, there is simply no evidence supporting this recommendation for the average household. Any contact with pets carries a very slight risk of disease transmission, just like any contact between people. There is currently no evidence, however, that sleeping with a pet in the bed increases the risk of disease. For your average pet and average household, this is probably exceedingly low risk and the recommendation is very difficult to justify. It is a reasonable recommendation when the pet is known to be carrying something that is transmissible to people (such as MRSA or Salmonella) or when a person has a compromised immune system. Banning pets from the bedroom completely doesn’t make any sense.

Personally, my dog is not allowed in my bed. However, that’s not because of disease concerns, it’s because she’s a large dog that snores and certainly can be a bed-hog. I have no problems with my cat on the bed. Life is never completely free of risk. If you enjoy having your pet in the bed, and you’re both healthy, I don’t see a reason to stop.

Are cats the root of all evil?

A Letter was just published in the New England Journal of Medicine about a woman with recurrent methicillin-resistant Staphylococcus aureus (MRSA) infections and her cat. MRSA is a hot topic because it’s a big cause of disease in people and there are indications that it can be transmitted between people and pets (in both directions). She kept getting recurrent infections and they eventually cultured MRSA from her cat. The cat was not sick and was a carrier. That’s something that we’re seeing increasingly, although we don’t know whether the pets are actually involved in transmission or whether they are innocent bystanders that are infected by their owners. The concerns that I had with this Letter revolve around the fact that the cat was treated for MRSA (in my experience, carriage of MRSA by dogs and cats is transient and antibiotics aren’t needed), they never tested the cat after treatment but they declare that the woman’s infections only ceased after the cat was treated. The problem is, the cat may have gotten rid of MRSA despite the antibiotic treatment, the owner may have handled the cat differently after finding out it was MRSA positive and therefore decreased the risk of transmission, or it may never have played a role in her infections.

Unfortunately, this Letter may lead to unnecessary treatment of pets that carry MRSA or over-assumption of the role of pets in human infections. It also meant that I was stuck doing rounds and rounds of interviews with reporters wanting comments. The key take-home messages from this are:

- Pets are part of the household and should be considered if a household disease investigation is undertaken.
- While pets may sometimes be involved in transmission of MRSA, simply finding MRSA in a pet does not mean that it has infected anyone.
- There is currently no indication that we should be using antibiotics to get rid of MRSA colonization in pets because they almost invariably get rid of it on their own.

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