As multidrug-resistant bacteria such as methicillin-resistant Staphylococcus pseudintermedius (MRSP) become more common in pets, there are increasing questions about how to manage animals that carry them. A particular issue is what to do with carriers – animals that don’t have any sign of disease but still carry the bacterium.

A small but increasing percentage of healthy dogs and cats are currently carrying MRSP in their nose or intestinal tract. The rates appear to be shooting up in most areas, and I suspect that the current carriage rate in a lot of regions is above 5%. In some groups of animals, particularly those that have received repeated courses of antibiotics, rates are likely much higher.

Back to the initial question… what to do with MRSP carriers?

Well, in some ways, we want to limit their contact with other animals to reduce the spread of the bacterium. However, we also have to realize that this is now a rather common bacterium, and it doesn’t cause infections in the majority of animals that get exposed, and it is very rarely a problem in people. That doesn’t mean we should ignore it, but it’s a lot easier to justify being very strict with a bug that:

  • is readily transmitted to people and can cause disease in people.
  • is rare in the dog population.
  • is highly infectious.
  • usually causes disease when an animal is exposed.

These aren’t the case with MRSP. It’s still certainly a serious concern, but where do we draw the line between being proactive and being impractical?

Back to the title of the post… what to do with MRSP-positive dogs that go to dog parks?

It’s a good question, and I don’t have an answer in which I’m 100% confident. The paranoid infectious diseases part of my brain wants to keep MRSP carriers away from other dogs to reduce transmission. But, the practical part of me recognizes that parks are probably a limited source of transmission overall, that there are probably greater risk factors for the increase in MRSP, that we have no idea whether short-term contact such as meeting in passing at a dog park can result in efficient transmission, and that going to the park is an important activity for many people and their dogs.

Anyone that takes their dog to a dog park needs to understand they are increasing the risk of infectious disease transmission to (and from) their dog. This includes a wide range of bacterial, viral, parasitic and fungal diseases, not just MRSP. In fact, I think there are other pathogens that are a bigger concern from dog park exposure.

Should MRSP dogs be keep away from dog parks?

  • When they have an active infection and are presumably shedding larger numbers of bacteria: Yes.
  • When they are just carriers: Probably not.

How can I say that when I keeping talk about how big a deal MRSP is?

  • It’s a big deal, but it’s mainly a big deal in specific circumstances, such as in dogs undergoing surgery, dogs with underlying skin disease and dogs that are exposed to antibiotics. There is no such thing as a no-risk dog, but the individual risk for a healthy dog is probably very low.
  • You have to live. You can do the Howard Hughes model of infection control and barricade yourself in your room, or you can live life. Yes, that increases risk. But, we do things to contain that risk as much as possible, such as keeping sick dogs away from parks (to prevent both transmitting and picking up microorganisms), reducing antibiotic use and using good general hygiene practices.
  • You don’t want to purposefully infect other dogs, but the small number of known MRSP carriers is dwarfed by the thousands of dogs that are unknown carriers.
  • In some respects, MRSA is the human version of MRSP, and it’s a huge health problem. However, MRSA carriers are not locked away. We realize they are transmission sources but we focus efforts on carriers only in high risk situations, such as hospitals. Could we greatly decrease MRSA carriage in people by aggressively testing, treating and quarantining? Sure. Is it worth it? That’s pretty questionable.

I never want to give the impression that we are being lax with an important infectious disease, but I just don’t have the evidence (or anecdotes) that restricting park access for carriers will do anything for MRSP control, especially since known MRSP carriers probably represent 0.0001% of all MRSP carriers.

What can you do to reduce the risk of transmitting or acquiring MRSP at the park?

  • Pick up feces. Dogs can shed MRSP in feces, and this could be the most important route of transmission given how some dogs like to nose and eat feces (my dog being the poster child for that particular habit).
  • Watch your dog closely so it doesn’t eat feces (or at least is less likely to).
  • Don’t let your dog have contact with an animal with any signs of an infection, particularly a skin infection.
  • Try to limit nose-nose, nose-bum contact (of the dogs… I assume you’re limiting that type of contact between yourself and other dog walkers).
  • If you have a dog that is high-risk for getting an infection, consider keeping it away from the park, reducing the amount of time it spends in the park or limiting off-leash time. This includes dogs with wounds, dogs that have recently had or are going to have surgery, dogs with active skin disease, dogs on immunosuppressive therapy (such as steroids), and dogs on antibiotics, among others.

More information about MRSP can be found on the Worms & Germs Resources page.

(click image for source)