OBJECTIVE To characterize
platelet-activating factor (PAF)-induced
edema and
erythema in the skin of dogs and compare those reactions with
histamine-induced cutaneous reactions. ANIMALS 6 healthy Beagles. PROCEDURES Experiments were performed at ≥ 2-week intervals. Each dog received ID
injections (5 μg/site) of PAF C16, PAF C18,
lyso-PAF, and
histamine.
Edema (mean diameter) and
erythema scores (none, mild, moderate, or severe) were assessed 30 minutes after the
injections. Dogs received ID
injections of PAF and
histamine each with various concentrations of
WEB 2086 (PAF receptor antagonist) or underwent ID testing with PAF and
histamine before and 3 hours after
oral administration of
cetirizine hydrochloride or
prednisolone (at 2 doses each). RESULTS ID
injections of PAF C16 and PAF C18, but not
lyso-PAF, induced comparable levels of
edema and
erythema. The PAF-induced
edema and
erythema peaked at 30 minutes and lasted for 6 hours after the injection;
histamine-induced
edema and
erythema peaked at 30 minutes and lasted for 3 hours after the injection.
Edema sizes and
erythema scores were significantly smaller and lower, respectively, for PAF than for
histamine. The
WEB 2086 inhibited PAF-induced but not
histamine-induced
edema and
erythema.
Cetirizine slightly, but significantly, repressed PAF-induced
edema and
erythema as well as
histamine-induced cutaneous reactions.
Prednisolone suppressed both PAF-induced and
histamine-induced
edema and
erythema. CONCLUSIONS AND CLINICAL RELEVANCE In canine skin, the duration of PAF-induced
inflammation was longer than that of
histamine-induced
inflammation. The PAF- and
histamine-induced cutaneous reactions were effectively suppressed by
oral administration of
prednisolone. The importance of PAF in dogs with
anaphylaxis and allergic disorders warrants further investigation.