Dogs:
Pruritus (scratching. licking, chewing, rubbing), initially with mild or no visible lesions Areas most commonly affected include muzzle, periocular region, ear canals/pinnae, interdigital spaces, axillae, and groin.
Self-trauma, redness, and secondary skin changes may be noted, particularly in chronic cases.
Saliva staining of hair may be noted. Secondary bacterial and yeast infections of skin and ears, and acute moist dermatitis hot spots”) may also be noted.
Cats:
Pruritus-initially with mild or no visible lesions-rapidly leading to excoriation, especially face, pinnae, and neck
Etiology
Dogs and cats are most commonly sensitized to house dust and storage mites, molds, pollens.
TREATMENT
Antihistamines should be administered with food to minimize gastrointestinal side effects. Antihistamines are given for 2 weeks. They may be synergistic with omega-6/omega-3 fatty acids, glucocorticoids. Side effects such as drowsiness, lethargy, or nervousness are sometimes noted. Reducing the frequency of administration and dose may minimize these effects.
Oral antihistamines showed to be of benefit
for dogs include:
Chlorpheniramine 0.4 mg/kg PO q8-12h
Cetirizine 1 mg/kg PO q 24h
Antihistamines showed to be useful in cats include:
Chlorpheniramine 2 to 4 mg/CAT PO q12h
Cetirizine 5 mg/CAT PO q 24h
Pentoxifylline
Phosphodiesterase inhibitor with numerous immunomodulatory actions that may be effective as a stand-alone drug, glucocorticoid-sparing agent, and in synergism antihistamines/ omega-6/omega-3 fatty acids
Dogs: 25 mg/kg P0 q 12h with food (frequent vomiting on empty stomach) for a 4-week trial
Contraindications include bleeding diatheses and pregnancy.
Corticosteroids
Effective for controlling pruritus associated
with environmental allergies, Prednisone or prednisolone at an initial daily dose of I mg/kg for dogs before weaning to an alternate-day schedule is regarded as the first choice when using glucocorticoid for atopic dermatitis. Prednisolone at an initial daily dose of 2 mg/kg is preferable in cats.
Cyclosporine is a calcineurin inhibitor and potent immunomodulatory agent.
Topical antipruritic therapy:
A cool bath has an antipruritic effect related to the cooling effect of evaporation and rehydrating of the skin.
Mild cleansing or moisturizing (e.g., colloidal oatmeal) shampoos +/-conditioners may also be beneficial.
Topical glucocorticoids are useful for focal areas of pruritus