Facial Pemphigus foliaceus (PF) in the Chow Chow/Akita
This form of pemphigus can be very refractory to treat and is likely a different entity to the naturally occurring truncal
pemphigus in other breeds. This form of PF is probably a bit deeper in the dermis histologically than the routine cases of
PF. The immunologic mechanism involve antibodies produced against the intercellular substance that "holds" the epidermal skin
cells together, thus resulting in dissolution of the cell-to-cell cohesion.
As a result, the canine immune system recruits neutrophils to repair and fill the void in the "space" that has been created
by the epidermal cell-to-cell dissolution. This quickly results in a very large pustule (neutrophil-laden, by definition)
that spans multiple hair follicles and clinically presents in large crusts due to the fragile and transient nature of the
pustules. Most of these pustules occur on the face, paw pads, trunk, nipples and limbs.
Cytology and biopsy are techniques to make a definitive diagnosis. I have occasionally based treatment on a diagnosis solely
from cytology, but I would advise against this technique in private practice.
Once diagnosis is made, the treatment focuses on immunosuppression and includes oral corticosteroids and other agents. Prednisone
at 2-4mg/kg/day accompanied by azathioprine or chlorambucil is highly recommended. It seems that most dogs with PF are affected
long-term, so it therefore seems advisable to incorporate alternative therapies to corticosteroids early on in treatment.
Other single-agent therapies include oral cyclosporine (5-20 mg/kg/day). Alternatives to these therapies also include oral
tetracycline and niacinamide. Dogs greater than 20 kg are administered 500 mg tetracycline and niacinamide every eight hours,
and dogs less than 20 kg are given 250 mg of these two drugs every eight hours. These drugs are immunomodulatory and can aid
in the treatment of immune-mediated skin diseases. Lastly, injectable gold therapy can also be considered as a single agent.
Feline cutaneous herpes infection
Since the discovery of cutaneous feline herpes infection several years ago, it has been clear that this disease can be chronic.
Herpes infection in the cat involves mainly the haired skin of the face but can involve the planum nasale, too. Some cases
are preceded by several months or years of upper respiratory symptoms, including episodic sneezing and conjunctivitis. Most
of the cases of cutaneous feline herpes infection occur during adulthood. In fact, many cases occur in older cats greater
than 5 years of age. After this initial upper respiratory disease, the owner notices lesions on the planum or more likely
haired skin of the muzzle. These lesions usually are ulcerated and very crusted. Cytology and histology can reveal primarily
eosinophils and some neutrophils, and can mimic eosinophilic granuloma clinically and more likely, histologically. Diagnosis
is based upon clinical examination and usually results of histopathology. Often epidermal inclusions bodies of the herpes
virus are seen, but not always.
Treatment has included oral lysine, oral interferon, topical and oral acyclovir, and more recently, oral Famvir. Famvir is
the trade name of an oral anti-herpes medication for humans, and I have found it to be very helpful and safe in cats. The
dosage is 125 mg (one-half of a 250 mg tablet) every eight hours. It costs about $175-200 for a three-week supply. I have
not found the other therapies to be of benefit. Famvir is usually administered for at least three to four weeks. The disease
is often chronic, and relapses are very common.
Next month Dr. Vitale will round out the other six worst cases in Derm’s dirty dozen.