Hypopigmentation in Dogs Treated with an Inhibitor of Platelet Aggregation

Abstract

Hypopigmentation was the principal manifestation of systemic toxicity when the experimental platelet aggregation inhibitor, PD-89454, was orally administered lo Beagle dogs for 28 days. Pigmentation changes were present in skin of nose, lips and eyelids and mucosa of hard palate. Fontana-Masson stain demonstrated decreased melanin within melanocytes and keratinocytes. Melanocytes were globoid with inconspicuous dendritic processes and had small, incompletely pigmented melanosomes that were quantitatively reduced relative to controls. Toxic mechanism of action of PD-89454, structurally distinct from known depigmenting compounds, was not established but ultrastructural findings suggest an interference in melanosome formation and/or melinization.

Proliferative and Non-Proliferative Lesions of the Rat and Mouse Integument

“…in coat color mutants, could also be classified as a dysplasia. ( 130 Walsh and Gough, 1989; 110 Sells and Gibson, 1987; 86 Nakamura et al, 2001)…”

A variation of pigmentation in the glabrous skin of dogs

“…However, since the investigated dogs were reported healthy, the observation of dermal melanocytes corroborates our findings. Walsh and Gough () reported hypopigmentation in eight beagle dogs treated with a toxic platelet aggregation inhibitor. Their observations included the nose, which showed hypopigmentation upon treatment.…”

Digestive System

“…An experimental inhibitor of platelet aggregation, which produced pigment loss in the dark hair of Long-Evans rats and the skin of beagle dogs, also induced pallor of the normally pigmented oral mucous membranes in dogs. 22 Apart from loss of pigment, the histology of the mucous membranes and skin was normal.…”