Skin infections in dogs, known as pyoderma, are usually caused by a type of normal skin bacteria known as staphylococcus intermedius. This bacteria is always present on the skin and the mucous membranes but in some cases it becomes rampant on the skin and leads to severe infections. Often these conditions include an immune related disease in the dog, malnutrition, injury or trauma or other change in the dog's environment or diet that causes the dog to become stressed.
There are several different types of pyoderma that can be found on a dog. They are categorized by the level of tissues they involve and range from the surface infections known as surface pyodermas to the very deep infections that can be caused by excessive scratching and biting of the infected area. They are also determined to be primary, or the cause of the infection, or secondary, the result of some other condition or wound that then allowed the bacteria access to the dog's skin.
Surface pyoderma is first noted as scaling of the skin, often around the area where the hair emerges from the skin. The scaling may seem to be attached to the hair and often can be slid off down the hair follicle. There may be small pimple like pustules on the area or the dog may even experience hair loss where the scaling is heavy. Surface pyoderma is more common in short haired breeds and typically the infected or inflamed area of the skin is on the head, neck and body, not on the legs or tail. The inflammation of the skin causes the hairs to stand up very straight, even if they normally were flat against the dog's skin. In addition the hair can easy be pulled from the skin with just the fingers, and this is important in diagnosing this condition from other skin conditions such as flea allergies. In the longer haired collie breeds the same trends can be noted but there are rarely the pustules associated with the red scaly patches. Hair loss will occur across small and large areas of the body and head.
In deep pyoderma caused by the staphylococcus intermedius the area will be crusty, have a discharge of puss and blood and be very horrible smelling. The skin will be very painful and sensitive and the dog will be highly stressed with the condition. They areas affected by deep pyoderma will lose hair but will also have lesions, swelling and inflammation and be very hot to the touch.
Superficial pyoderma caused by staphylococcus intermedius can be treated with topical and oral antibiotics usually prescribed for up to 30 days but chronic conditions may need 8-12 weeks of antibiotic treatment to ensure that the problem has been corrected. Deep pyoderma will require regular, frequent bathing with antibacterial shampoos, professional grooming to clip the coat and keep the dog free from any possible superficial pyoderma problems, oral and topical antibiotic treatments as well as testing for any other complications that may be leading to the development of the deep pyoderma.