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Staphylococcal Infection in Rats

Staphylococcal infection in rats is caused by a bacteria belonging to the genus staphylococcus, a gram positive bacteria that is commonly found on the skin of many mammals, including rats, and which includes a number of species and subspecies, most of which are harmless to the body and are not implicated in disease.

When the immune system of the rat is compromised as a result of disease or other stressful conditions, staphylococcal numbers can flare up. Under these circumstances, if a rat happens to have an old unhealed wound, a fresh cut, or a fight wound, the staphylococcal bacteria can gain entry inside the body through these open wounds, resulting in a staphylococcal infection. The staphylococcal infection gets progressively worse when the rat keeps scratching at any injured part of the body.

Although this infection can occur in many species besides rats -- including humans -- it has not been found to be transmissible to humans by rats.

Symptoms and Types

• Inflamed skin and sores on the head and neck
• Formation of abscesses (pus filled swellings), which in turn may enlarge and spread under the skin to form lumps (tumors) around the face and head
• Ulcers or pus filled bumps on feet (ulcerative pododermatitis, or bumblefoot)
• Intense itching/scratching of affected areas
• Swollen belly due to internal swelling

Causes

This infection is caused by the presence of the staphylococci bacteria that is commonly found on the skin of most animals. While most staph bacteria remain harmless, some species can cause a diseased state of infection when they are able to gain entry into the body. One of the most common types of disease producing staphylococci bacteria is the S. aureus. Infection typically occurs when the skin is damaged by scratching or bite wounds, or when the skin is injured due to small abrasions.

Rats can acquire the infection from soiled bedding, or from coming into contact with infected urine or feces. Cages with wire mesh flooring have been implicated in increasing the incidence of foot lesions and subsequent infections of the foot. Rats with weakened immune systems are most likely to become infected.

Diagnosis

A diagnosis can often be made by the symptoms observed, but a fluid sample of the abscess will be necessary for a confirmation of the infection. Discharges from the affected areas can be collected and cultured in a bacterial culture medium. The diagnosis is confirmed by a bacterial culture of skin scrapings and fluid samples from the infected area.