Causes of Dogs Sores on Skin

Dog sores on the skin can have a number of causes. Skin sores can occur as a result of skin conditions, but they can also occur as an outward symptom of internal illness. Here's what you should know about dog skin sores and their causes.

Types of Dog Skin Sores

There are as many types of dog skin sores as there are causes of dog skin sores. Dogs may develop inflamed, itchy bumps known as papules. Some skin sores may weep constantly and never heal. Others may quickly become infected. 

Skin sores on dogs can often be accompanied by crusty, flaky skin. 

Causes of Skin Sores on Dogs

Papules are usually the result of bacterial, fungal or parasitic infection. Ringworm, pyoderma and mange are all common causes of skin sores in dogs. Food and contact allergies may also be responsible for papules on your dog's skin.

Lesions that weep constantly, without healing, may be the result of a serious bacterial or fungal infection. Non-healing, weeping lesions may even be a symptom of cancer.

Common causes of skin sores on dogs include:

  • Flea allergy dermatitis
  • Acral lick dermatitis, in which dogs lick themselves obsessively and eventually injure their own skin
  • Bee stings and insect bites
  • Frostbite
  • Hemangiosarcoma, a cancerous skin tumor usually caused by overexposure to UV rays
  • Hot spots, an acute form of dermatitis that can occur due to flea or other allergies, mange or bacterial infection
  • Lice
  • Lymphoma
  • Mammary cancer
  • Mast cell tumors
  • Rocky Mountain Spotted Fever, a disease spread by ticks
  • Melanoma

Skin sores may also appear as a result of drug reactions or drug side effects. This can be true even if your dog has been taking the same medications for a long time prior to the appearance of his skin sores.

Symptoms of Skin Sores on Dogs

Skin sores on dogs typically cause itchiness, inflammation, soreness and irritation of the skin. Discharge from your dog's sores may be clear and thin, or thick and opaque if infection is present. Crusty, flaky areas may appear, especially surrounding the sores. Your dog may lick, chew or bite at his sores.

Diagnosing Skin Sores on Dogs

Your vet will need to perform a thorough physical exam and a complete medical history in order to diagnose the cause of your dog's skin sores. Your vet may ask detailed questions about your dog's symptoms and when and how they first appeared. If you have traveled recently, or if your dog's skin sores appeared following a change in his normal routine, you should tell your vet. If your dog is taking any medications or nutritional supplements, make sure to tell your vet.

Your vet will probably take samples of any discharge from your dog's sores, and he may take scrapings of your dog's skin. Your vet may be able to diagnose the cause of your dog's sores by examining these samples in the lab. If your vet suspects skin cancer, he'll take a tissue sample for biopsy.

Treating Skin Sores on Dogs

Your dog may need antibiotics and other medications for up to four months. Topical medications and shampoos may be prescribed. Follow your vet's instructions carefully and administer all medications as recommended. Don't allow your dog to swim, since it puts him at risk of further infection.

Make sure to ask your vet if your dog's condition is contagious to other dogs, animals or humans.