Several dogs at a Miami humane society were quarantined last week because of concerns (or possibly panic/over-reaction) about methicillin-resistant Staphylococcus aureus (MRSA). MRSA in dogs is a concern because it’s an important cause of infection in both people and animals. However, it’s an opportunist, meaning it typically doesn’t cause disease when it encounters a normal, healthy person or animal. In fact, a small percentage (~1-3% probably) of the human and pet populations carry this bacterium in their nose without knowing it, and the vast majority never suffer any consequences.
It’s often tough to strike the right balance when dealing with an MRSA issue. We want people to realize that it’s an important cause of disease and that it needs to be taken seriously, but we also want people to keep it in perspective and not freak out.
The Miami shelter report seems to be on the "freak out" side, particularly on the part of the local media.
It’s not really clear what’s happening based on this fairly poor article. The shelter’s Chief Medical Officer, Dr. Maureen Swan, is quoted as saying there’s a routine respiratory disease cluster in the shelter, but MRSA rarely causes respiratory disease in dogs. The article then adds Dr. Swan said it was "not the highly contagious MRSA virus." I have no idea what that means, and MRSA is not a virus.
My suspicion is that they have respiratory disease caused by the typical bacterial and/or viral pathogens that are commonly found in shelter dogs, and that they isolated a methicillin-resistant staph that just happened to be hanging around in that particular dog (since such bacteria normally live in the mouth, nose and skin). It’s also not really clear whether this is MRSA. The article says MRSA, but the first thing I ask when I get an advice call about MRSA is "what staph species does the report say was isolated?". Most often, it’s Staphylococcus pseudintermedius or another staph. These bugs can still be relevant, but they don’t carry the same human health risk as MRSA, so it’s important to know exactly what’s been found.
Finding MR staph, including MRSA, isn’t unheard of in a shelter. It’s just one of many reasons that good general infection control practices are needed in these facilities. When MRSA is found, taking some extra precautions is reasonable because of the potential for disease and transmission to people, but too often people panic. It’s understandable based on concern about MRSA and the scary stories people can find with a quick Google search. Not uncommonly, there’s a combination of an short-term overly aggressive response while at the same time failing to improve basic infection control practices, which are the most important.
More information about MRSA can be found on the Worms & Germs Resources – Pets page.