Methicillin-Resistant Staph aureus (MRSA) Infection in Dogs
Some strains of the Staphylococcus aureus bacteria are resistant to standard antibiotics. When the organism is resistant to methicillin and other beta-lactam types of antibiotics, they are referred to as methicillin-resistant Staph aureus, or MRSA.
Staphylococcus aureus, also called Staph aureus or S. aureus, is a specific type of bacteria. It is commonly encountered and normally does not cause illness unless a person or pet becomes ill or injured, in which case the bacteria can become opportunistic and cause an infection.
People can be carriers of Staph aureus and may be otherwise perfectly healthy. This is referred to as colonization. Though dogs are not normally colonized with Staph aureus, if your dog is exposed to a person that is colonized or who has an active infection, your dog can become infected or colonized as well.
- Fever
- Discharge from a wound (even a wound that looks small can be severely infected, as the infection can go deep rather than wide)
- Skin lesion(s)
- Skin swelling
- Slow to heal wound(s)
Dogs kept as pets can become colonized or infected by MRSA organisms through exposure to colonized or infected people. Risk factors that may increase the chance of MRSA infections include previous surgery, hospitalization, and/or antibiotic use. Therapy pets, particularly those used in hospital visitation programs, may also be at increased risk.
When exposed to an MRSA organism, your dog may be colonized, in which case the MRSA bacteria may be present in your dogs nose or anal region. Colonized dogs are considered to be carriers of the disease and are often asymptomatic, appearing perfectly healthy.
Alternatively, your dog may also become infected, particularly if he has pre-existing wounds. Dog can be both colonized and infected simultaneously under the right circumstances.
Most dog are exposed to MRSA infections through human contact. However, once colonized or infected, your dog can potentially pass the disease to other animals, as well as to people.
Diagnosis is usually accomplished through a bacterial culture. Samples for culture may be collected by swabbing the nose or anal region of a suspected carrier, or by culturing an infected wound directly, if present. By definition, if a Staph aureus organism that is resistant to methicillin is isolated, a diagnosis of MRSA is established. In reality, oxacillin (an antibiotic closely related to methicillin) is the antibiotic used to test for susceptibility. Staph aureus organisms that are resistant to oxacillin are considered to be MRSA.
For dogs that are colonized with MRSA and are otherwise healthy, treatment is usually not necessary. In most cases, assuming that the dog is not re-exposed to the bacteria, your dog will successfully clear the infection, usually within a few weeks. However, attention to sanitary practices is recommended, including household disinfection.
For dog with MRSA infections, local wound treatment is important and may consist of lancing and draining any abscesses, keeping wounds clean and bandaged, and following any directions provided by your veterinarian. Antibiotics are normally chosen based on testing to determine which medications are most effective in killing the bacteria. Finish all antibiotics prescribed for your dog even if his symptoms seem to be improved before the medication is finished.
If your dog is colonized or infected with a MRSA, there are several things you can do to prevent transmission.
To prevent spread of MRSA infections to your pet, hand hygiene is important. If you or a family member are suffering from an MRSA infection or are colonized, wash your hands thoroughly and often using soap and water. Also, avoid kissing your dog or allowing your dog to kiss you or come into contact with any broken skin.
Symptoms Of MRSA Infection In Dogs
The symptoms of MRSA infection in dogs are similar to a normal staph infection, but they do not disappear with antibiotic treatment and continue to worsen. Infections can appear anywhere on the skin, but often affect the ears and sites of wounds, especially after surgery.
If your dog’s staph infection is not clearing up with treatment, MRSA may be the cause. Here are some symptoms you should look out for:
Diagnosis of Methicillin-Resistant Staphylococcus Aureus in Dogs
When your veterinarian suspects Methicillin-Resistant Staphylococcus Aureus in your dog, they will take precautions to prevent the bacteria from spreading to their staff or to the other dogs at the veterinary clinic.
MRSA infections are diagnosed by collecting a sample from the lesions that are present and performing a bacterial culture and antimicrobial susceptibility testing. The samples that your veterinarian collects will be sent to a veterinary reference laboratory for testing, therefore, it can take a few days for the test results to come back to your veterinarian.
Signs and Symptoms of MRSA
MRSA/MRSP (Methicillin-Resistant Staphylococcus aureus (MRSA), Methicillin-Resistant Staphylococcus pseudointermedius (MRSP))
We receive many phone calls from clients asking us to refill antibiotics, oral or topical, for their pets for problems that occur frequently, such as skin and ear infections, sneezing, or urinary tract infections. Antibiotics at our office are generally not refilled without checking your pet. We need to see your pet before refilling antibiotics, which can cause confusion and frustration for our owners.
These bacteria aren’t called superbugs for no reason. They are normal bacteria that have mutated to become resistant to multiple antibiotics. The reasons for the mutation is simple…misuse of antibiotics. Misuse refers not only to the judicious refilling of antibiotics, but also not finishing a course of antibiotics as prescribed, reusing leftover antibiotics (including ear medications), or not using antibiotics at the proper dose or duration.
The development of superbugs is not one to take lightly as these infections are becoming common not only in veterinary medicine, but also in human medicine. In addition, MRSA and MRSP can spread to humans from their pets and vice versa.
Staphylococcus aureus is a common bacteria that lives on people, normally on the skin or in the nose, and can be spread from people to their pets. Staphylococcus pseudointermedius is a similar bacteria that normally lives on dogs. In some pets, both of these “normal” Staph bacteria can cause infections, usually of the skin or ears.
MRSA and MRSP are Staphylococcus aureus and Staphylococcus pseudointermedius that have developed resistance to multiple antibiotics. MRSA and MRSP can be found on healthy pets and are usually harmless. Pets that are sick, hospitalized, or taking antibiotics are prone to infections from MRSA and MRSP. The bacteria most commonly cause skin or ear infections similar to “normal” Staph bacteria. However, since MRSA and MRSP are resistant to multiple antibiotics, infections need to be identified for proper treatment.
Other infections, such as urinary tract infections or pneumonia, can also be caused by MRSA and MRSP. If left untreated, MRSA and MRSP can lead to other serious disease such as sepsis.