The remaining two allergies also can be difficult. Food trials with either hydrolyzed protein or novel proteins are recommended
for at least eight weeks. Cats are very finicky, can show disinterest in the food, develop weight loss and gastrointestinal
signs. This results in frustration and lack of owner compliance. I generally recommend Hill's ZD (dry only) with supplementation
with canned rabbit-based cat food. Cats enjoy these foods, tend to do well with this combination and usually do not lose weight.
Atopic cats should be referred for a thorough work-up by a boarded veterinary dermatologist as these cases can be difficult
Finally, pyschogenic alopecia can be a diagnosis of exclusion and can sometimes can be successfully managed with amitriptylline
(5 mg/cat twice daily). I should note that this drug might also have some anti-histaminic effects as well. Fluoxetine may
also be used (1-3 mg/kg/day), but side effects might be seen more readily, such as vomiting or diarrhea and undesirable behavior.
This is a genetically-based disease observed in the American Cocker Spaniel and other breeds. The basic pathology is an abnormal
acceleration/proliferation in the epidermal and sebaceous gland cell turnover rate. There have been several studies that evaluate
the kinetics of this hyperproliferative state, and the epidermal cell renewal rate has been calculated at eight days. Normal
epidermal cell renewal rate is about 21 days. This results in a major traffic jam of cornified cells, resulting in seborrhea
or excessive flaking on the skin that we observe clinically.
Clinically, most dogs present with what is termed seborrhea sicca or dry seborrhea. Much scale is observed on the coat, predominantly
on the trunk. Some scales can be seen in the axillae and groin more readily. It is known that seborrhea sicca can be pruritic,
and this can be the owner's primary complaint. Some Cocker Spaniels can develop greasy seborrhea (seborrhea oleosa) and have
a profound odor. Lesions can extend to involve the pinnae and ear canals, resulting in proliferative otitis.
Some of these dogs effected by primary seborrhea can develop secondary skin infections with Staphylococcus and Malassezia
on the skin and in the ear canal, which can increase pruritus and odor further. Cytology can help elucidate these cutaneous
infections and is best performed with direct glass slide impressions.
Diagnosis can be difficult because seborrhea is more commonly seen secondary to other causes, such as allergy. The best diagnostic
tool (after the elimination of infections) is the skin biopsy. A diagnosis of primary seborrhea can be made with this technique
and should be reserved for cases that are highly suspect.
Treatment involves antibiotics for the concurrent pyoderma and anti-fungal therapies for Malassezia dermatitis (oral and topical
if severe). Shampoo therapy (performed every three days to five days) is also very important and includes soap-free moisturizing
shampoos for mild, dry seborrhea or products that contain sulfur and salicylic acid. In severe cases, especially in greasy
seborrhea with odor, I generally recommended benzoyl peroxide or tar-containing shampoos. Rinses with water-based humectants
can be a benefit as well.
Systemic therapy has been advocated for severe cases and can include oral fatty-acid supplementation (follow labeled instructions)
and oral retinoic acids or synthetic retinoids. Accutane has been used in the past and more so recently because generic equivalent
is available. The dosage is 1-3 mg/kg twice daily, but results can be disappointing. Finally, Soriatane (acitretin) at dosages
of 1 to 2 mg/kg/day may be of benefit as well.
High dosages of vitamin A can act on the skin much in the same way as the synthetic drugs. It is much less expensive than
the synthetic retinoids. I generally recommend 16,000 IU twice daily or higher for three months or more to evaluate effect.
The last two frustrating dermatology-related problems that I experience, are actually not skin diseases at all: owner compliance
and expense of treatment.