chapter 15 Biting and Stinging Insects...............................
DEFINITION/OVERVIEW
Insects produce dermatitis by bite, sting, or percutaneous absorption of allergens.
Allergenic substances are present in saliva, feces, and body parts, as well as in venom.
Atopic dogs more commonly have positivein vitroreactions to insect allergens than
nonatopic dogs living in the same environment.
There is significant cross-reactivity between mite and insect allergens and between
the various insect allergens.
In vivoreactions to these allergens may be due to direct irritation and/or injury to tis-
sues (nonimmune-mediated response) or due to hypersensitivity (immune-mediated
response).Insects as vectors of disease should not be underestimated.
Of most importance to the small animal practitioner are reactions to fleas, spiders,
flies, mosquitoes, ticks, and hymenoptera.
Dermatitis caused by ants may be by direct envenomation or by absorption of aller-
gens; symptoms may appear similar to FBD/FBH and/or atopic dermatitis.
ETIOLOGY/PATHOPHYSIOLOGY
Flea Bite Dermatitis and Hypersensitivity
Flea bite dermatitis (FBD) and flea bite hypersensitivity (FBH) remain the most com-
mon causes of pruritic skin disease in dogs and cats, although the efficacy and con-
venience of flea control products have decreased the occurrence – in comparison to
other allergic dermatoses – in some locations.Fleas are small, wingless parasites that require a blood meal to reproduce; adult fleas
remain on the host although most life stages of the parasite occur in the environment.
More than 90% of fleas found on dogs and cats areCtenocephalides felis felis; other
species are often associated with atypical environmental situations.
C. felisdemonstrates a preference to remain on the rear half of the body; correlated
with a similar location for the majority of lesions in both FBD and FBH.
Echidnophaga gallinacea(sticktight flea) is seen in warmer climates and associated
with exposure to poultry (Figures 15.1, 15.2).
Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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