Some information I found at the following site. I see some similarities in Gunner's symptoms with those described for some of these autoimmune skin diseases:
http://www.canismajo...g/autoimmn.htmlAutoimmune diseases of the skinAs a group, autoimmune diseases of the skin are uncommon to rare in frequency. Diagnosis is often difficult, especially for the general practitioner who may see one or two cases during a career. Skin biopsy and immunofluorescent staining are generally required to diagnose one of these diseases, and the prognosis for recovery may vary. Our old friends the corticosteroids are the primary mode of therapy.
"Pemphigus complex" is a group of four autoimmune skin disorders characterized by "vesicles" and "bullae" (blisters), erosions, and ulcers. In "pemphigus vulgaris", common pemphigus, the lesions are usually found in the mouth and at mucocutaneous junctions, those borders of haired skin and mucosal tissues. Such areas include the eyelids, lips, nostrils, anus, and prepuce or vulva. There may also be skin lesions in the groin or axillae (armpits). The blisters are thin, fragile, and rupture easily. The skin lesions are described as red, weeping, ulcerated placques.
In contrast, the lesions of "pemphigus vegetans" are thick and irregular and proliferate into vegetative lesions marked by oozing and pustules. It is thought to be a more benign form of pemphigus vulgaris.
"Pemphigus foliaceous" is rarely found in the mouth or at mucocutaneous junctions. The blisters are only temporary; redness, crusting, scales, and hair loss are more common presenting signs. Pemphigus foliaceous usually begins on the face and ears and often spreads to the feet, footpads, and groin. Secondary skin infections are common, and fever, depression, and anorexia may occur in severe cases.
"Pemphigus erythematosis" looks clinically like foliaceous and is frequently found on the nose. Ultraviolet light aggravates this form of pemphigus and can lead to a misdiagnosis of nasal solar dermatitis (Collie nose). It is considered a benign form of pemphigus foliaceous. The term "bullous pemphigoid" sounds a lot like "pemphigus," and clinically this disease resembles that group of diseases. The same type of vesicles and ulcers may be found in the mouth, at mucocutaneous junctions, and in the axillae and groin. Differentiation is possible only through biopsy. Evaluation of the vesicles is critical to the diagnosis, and because they rupture so soon after formation, a dog must often be hospitalized and examined every two hours until the biopsies can be taken.
"Discoid lupus erythematosis" is thought to be a benign form of systemic lupus (to be discussed next month) and is an autoimmune dermatitis of the face. It is most common in Collies and Shelties; more than 60 percent of affected dogs are female. The lesion is often described as a "butterfly pattern" over the bridge of the nose and must be differentiated from nasal solar dermatitis and pemphigus erythematosis.
Finally, Vogt-Koyanagi-Harada-like syndrome (VKH) is an extremely rare syndrome, possibly of autoimmune origin, leading to depigmentation and a concurrent eye disease. The black pigments of the nose, lips, eyelids, footpads, and anus fade to pink or white, and there is an acute uveitis (inflammation of the eyes) Early treatment may prevent blindness, but the pigment loss is usually permanent. As you can see by the above descriptions, many autoimmune diseases are similar in appearance. Except for discoid lupus, there is no breed, sex, or age predilection for these problems.
As in other autoimmune diseases previously discussed, the primary goal of therapy is to suppress the body's immune response with large doses of systemic glucorticoids. More potent drugs like Cytoxan or Imuran are used if steroids fail. Gold therapy has been advocated for the pemphigus group or pemphigoid. In cases where nasal depigmentation has occurred, tattooing the affected area helps prevent the sunburn and squamous cell carcinoma that may follow.
The prognosis for discoid lupus is usually good, but it is variable in the other diseases. Many dogs with VKH are euthanized due to blindness. Breeding affected dogs is not recommended. Currently, little information exists on the heritability of autoimmune skin diseases.
Histeocytomas typically don't occur in dogs his age, let alone occur on three different feet at the same time. 
He has a vet appointment for tomorrow for his annual check-up, so I'll have the vet check him out again.
