Why Do Dogs Get Staph Infections?

A staph infection in dogs is caused by a group of bacteria known as staphylococcus. These bacteria inflict skin conditions that range from mild to severe. Various factors bring about staph infections, and on average they respond well to treatment. If they keep reoccurring, however, talk to your veterinarian about further testing.

Staphylococcus is a bacterium that not only lives on your dog on a daily basis, but you as well. It lives on the skin and mucous membranes of animals and humans. Staphylococcus aureus is a strain that tends to prefer people, horses and swine. Staphylococcus pseudintermedius tends to make its home on our companion friends. On average, staph lives peacefully with its host or even dormant. However, certain occurrences can trigger it into an infection.

Staph bacteria are considered opportunistic invaders, and what sparks the bacteria into an overgrowth varies. One of the most common causes for staph in dogs is when the immune system is compromised. In puppies, the immune system is still developing. In older dogs, it’s waning. Health problems, such as diabetes or cancer also play a role. If a dog has skin sensitivities, allergic reactions that cause itching open the door to staph infections. As he scratches, staph burrows into open pores causing inflammation.

Typical causes for allergic reactions involve food ingredients, grasses and pollen, especially during certain times of the year. Although rare, certain dogs have shown a reaction to the staph bacteria itself. A staph infection usually presents itself in one of two ways. One type involves redness and pimple-like pustules. The other includes crusty areas and hair loss. Since staph is a bacterium it usually responds well to a course of oral antibiotics as well as topical applications, such as medicated shampoos.

Methicillin-resistant staph is a strain of bacteria that has developed a resistance to penicillin-type antibiotics. In humans, this is often referred to as MRSA. Since dogs have a different strand of staph on their skin, it’s referred to as MRSP or MRSPi. MRSP usually does not present itself any differently than a regular staph infection, other than showing little to no improvement after a course of antibiotics. Veterinarians can make a definitive diagnosis with a culture swab or skin biopsy. The transfer of MRSP from pet to human is rare, whereas transfer of MRSA from human to pet is more likely.