Small Animal Dermatology, 3rd edition

242 DISEASES/DISORDERS

Hair coat barbering of the ventral abdomen and caudal thighs

Lesions of the eosinophilic granuloma complex (Figure 15.11).

Spider Bite Dermatitis

 Dogs and cats (Figures 15.12, 15.13):
Loxocelesspp.: initial local erythema surrounding puncture marks leading to

tissue necrosis and slough; lesions are painful

Latrodectusspp.: initial local erythema surrounding puncture marks leading to

granulomatous nodules; systemic effects due to neurotoxin release

Systemic signs include salivation, vomiting, convulsions, and death.

Fly Dermatitis

 Dogs:
Outdoor exposure, particularly warmer weather
Face and ears most affected
Bites most frequent on the tips of erect pinnae and the exposed ridge of skin on

dogs with folded pinnae

Initial lesions appear as punctate accumulations of dried hemorrhagic secretions

that result from oozing at the site of injury/fly bite (Figure 15.14)

Continued irritation causes severe erythema, ulceration, scabs, and secondary

infection (Figures 15.15, 15.16)

Thickened and scarred pinnal margins develop with chronicity

Lesions are often painful

Flies may serve as vectors for the mycobacteria seen in canine leproid granuloma

(Figure 15.17).

Mosquito Bite Dermatitis and Hypersensitivity

 Dogs and cats: irritation at the site of mosquito bite(s) (Figure 15.18).

 Cats: mosquito bite hypersensitivity (Figures 15.19–15.22):
Outdoor exposure, specific to seasonality of mosquitoes
Preference for darker hair coat and skin color
Pruritic lesions of papules and crusts leading to erosions and scabs
Lesions most often affect less haired regions of the dorsal muzzle, medial pinnae,

and lip margins

Lesions often well demarcated and symmetric

Medial pinnae may have a papular to nodular appearance

Occasional involvement of footpads with crusting

Lesions resolve when cat is confined/protected from mosquitoes.

Tick Bite Dermatitis and Hypersensitivity

 Tick ecology, populations, and disease transmission vary greatly by region.

 Irritation caused by direct damage to the skin by penetration of the epidermis and

laceration of superficial vessels to permit feeding (Figure 15.23)