Idiopathic Furunculosis (German Shepherds) in Dogs

Furunculosis is a skin disease that produces boils (also called furuncles) that are filled with pus. Often, the boils recur, typically on the nose, around the anus, back, abdomen, legs (particularly the lateral thigh), paws and muzzle. Other symptoms include:

• Pain
• Pus and/or bloody discharge oozing from the boils
• Over grooming where the infection is located
• Swelling or inflammation of tissue in the area that is infected
• In anal furunculosis, there may be straining when defecating
• Limping on the leg or foot that is affected
• The boils tend to develop quickly and lead to ulcerated skin 
• Lesions in skin where there is hair will often be covered by crusts
• More advanced cases may lead to boils throughout your dog’s body, with the exception of his head, ears, and front legs.

Types

There are several types of furunculosis, to include:

• Interdigital furunculosis

  - The infection will be between the toes of your dog, showing up as boils in the webbing between the toes of your dog’s paws

• Anal Furunculosis

  - The infection will produce boils in the groin and anal areas of your dog

Idiopathic means “without known cause”. In cases of idiopathic furunculosis, it is not clear what it is that has caused the infection. Furunculosis that is not idiopathic may be caused by certain bacteria, for example Staphylococcal spp., as well as conditions that are not hygienic combined with a weakened immune system. Furunculosis that affects the skin is typically due to bacterial, fungal or parasitic infection. Canine atopy and demodicosis are conditions that are known to cause furunculosis.

Interdigital furunculosis may be caused by:

• Bacterial infection as well as short hairs in the webbing of your dog’s toes that become forced into hair follicles upon his walking, causing inflammation and secondary bacterial infection
• Material that gets into your dog’s paws may then be implanted in the skin

Anal furunculosis may be caused by there being feces in the anal area that will attach to the tail of your dog. The tail will then spread the feces around the perineal area. This will cause the skin under the tail of your dog (around the anus) to become inflamed and ulceration will occur, possibly leading to infection. German Shepherds and German shepherd mixes are more likely to suffer from this condition than other dogs.

Upon diagnosis, your veterinarian will likely recommend antibiotics and topical antimicrobials. In many cases, antibiotics are given for a long period of time. Other possible recommendations include:

• Keeping the infected areas clean
• Trimming the hair in or near the area(s) where the boils are located to allow the discharge to be cleaned
• Using an antibiotic skin wash
• In interdigital furunculosis, surgery to remove foreign bodies
• In anal furunculosis, surgery to remove tracts that have developed under the skin

When treatment is not successful, it is often due to the dose or duration of antibiotics not being enough. Other reasons for unsuccessful treatment include your veterinarian being unable to identify and resolve any predisposing factors, as well as your dog taking corticosteroids while receiving treatment for furunculosis.

While your dog is undergoing treatment, you will want to keep the infected areas well ventilated and dry. In addition, it is important that you maintain proper hygiene for your dog and provide him with a diet that meets his nutritional needs in order to boost his immune system. This will help him better fight his infection. With treatment, you will typically notice symptoms receding within 4-12 weeks. It is fairly typical for symptoms to recede and then reoccur during treatment.

If your dog is predisposed to furunculosis, he will likely experience relapses. As furunculosis has a high likelihood of recurring, your veterinarian will probably recommend regular follow up visits. In some cases, the dog will require antibiotics throughout his life.