MRSP and Skin Infections in Dogs

90% of skin infections in dogs with allergies are caused by S. pseudintermedius, which is also a common cause of ear infections. 

MRSP stands for methicillin-resistant S. pseudintermedius. All MRSP strains are resistant to a commonly used group of antibiotics called beta-lactam antibiotics (e.g. penicillins). But some MRSP are also resistant to other groups of antibiotics as well.  That is why the bacteria must be tested in order to determine the best antibiotic.

Automatically choosing the most powerful antibiotic to treat the infection can be very dangerous, not to mention expensive, because if the bacteria become resistant to it, there may be no other drug that can effectively treat the infection. 

Opportunistic Pathogen

Typically, the pathogen causes not problems at all.  It is actually quite common on the skin or in the nose or intestinal tract of 50% of more of healthy dogs, and a smaller percentage of healthy cats. But  it is an opportunistic pathogen – if an animal gets injured or sick for another reason, the pathogen will take advantage of the already busy immune system and cause infection and illness.

It can infect almost any tissue, but skin, ear and soft tissue infections are most common, particularly when the skin has been damaged by something else (e.g. allergies, scratching, chronic wetness, wounds, surgery). 

Multiple Pet Households?

Healthy dogs in close contact with MRSP-infected dogs can acquire the bacterium, but rarely develop disease. The skin must be damaged for the bacterium to cause an infection.

Help Sheet for Pet Parents from the Canadian Academy of Veterinary Dermatology

CAVD has recently published a "MRSP Help Sheet for Pet Owners". You can find the link to the full handout sheet here:

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Source: The Bella Moss Foundation, CAVD

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