Bacterial skin infections are common in dogs. Generally secondary to other medical conditions or allergies, bacterial infections can be baffling to diagnose and tricky to treat. It's important that your veterinarian correctly diagnose the bacteria involved to get your dog on the correct antibiotic and treatment plan. Many bacterial skin infections are misdiagnosed and improperly treated, leading to more discomfort to the dog and unnecessary cost to the owner.
Although most bacterial skin infections are caused by a strain of Staphylococci bacteria, many different strains exist. Identifying the exact organism responsible for your dog's discomfort is critical for successful treatment. Administering the wrong antibiotic not only is ineffective, it can create antibiotic-resistant bacteria and, over time, further lower your dog's immune resistance.
Most cases of pyoderma are caused by Staphylococcus intermedius, according to Dr. Candace A. Sousa, DVM. Other bacterial organisms that can cause pyoderma, impetigo and bacterial skin infections include dermatophilosis streptotrichosis, E coli and the pseudomonas bacterium.
The symptoms of bacterial skin infection depend on the particular bacteria and the part of the dog involved. Different bacteria may be involved in the same infected area, and some infections can be indistinguishable from fungal or yeast infections. When the hair follicles are infected, the dog will have small pimples. Most skin infections cause red, irritated skin. In advanced cases, the skin can crack, weep and have an unpleasant odour. Hair loss and itching (pruritis) may occur.
Diagnosis: The Vet Visit
Because bacterial skin infections are almost always secondary to fleas, environmental or food allergies or several other illnesses, your veterinarian will take a complete health history on your dog, and do any other diagnostic testing she thinks may be warranted. Unless the allergy or underlying illness is addressed, your dog will continue to have recurrent or chronic skin infections.
Several skin conditions have the same symptoms so your vet will first test the skin to rule out mites or fungal infections. She will clip or shave the fur from the affected areas and apply antibiotic cleanser.
Because Staphylococcus intermedius is the most common bacteria, your vet may first treat the dog with oral erythromycin antibiotics, coupled with an antibacterial shampoo. For severe itching, she might prescribe antihistamines. If the skin doesn't clear up in two to three weeks, she will take a skin scraping and culture or grow the bacteria in a laboratory to determine the bacteria involved. Several antibiotic protocols can be effectively used on infections involving less common bacteria, or when there is more than one type infecting the dog.
Canine skin problems can be complex, and if the cause isn't addressed they can be stubborn and recurrent. Follow through any other treatment your veterinarian recommends. If your dog's skin problems do not resolve despite treatment, ask for a referral to a veterinary dermatologist or your nearest veterinary teaching hospital.