Small Animal Dermatology, 3rd edition

CHAPTER 15 BITING AND STINGING INSECTS 243

 Species of most significance (United States) includeRhipicephalus sanguineus,Derma-

center andersoni,Dermacenter variabilis,Dermacenter occidentalis,Ixodes ricini,Ixodes

scapularis,Ixodes dammini,andAmbylomma maculatum.

 Salivary toxin of species of ixodid ticks produce tick paralysis.

 Otobius megnini(spinous ear tick): larvae and nymphs in the external canal cause

irritation, pain, and infection, and potentially significant blood loss.

 Reactions may be caused from inflammatory or toxic components of tick saliva

(Figures 15.24, 15.25).

 Hypersensitivity causes focal necrosis, ulceration, and pruritus.

Hymenoptera Sting

 Ants, dogs and cats:
Fire ants (Solenopsisspp.) aggressively attack when disturbed.
Ants attach to the skin by jaws and may sting up to 10 times; hundreds of stings

may occur in one attack.

Stings may initially be painless.

Individual stings result in pruritic and erythematous urticaria and papules lead-

ing to sterile vesicles/white pustules; they may lead to focal necrosis (Fig-

ure 15.26).

Lesions tend to be grouped and nonfollicular.

Anaphylactic shock is possible.

Venom contains solenopsin D, an alkaloid piperidine derivative.

Hypersensitivity reactions to ant allergens (similar to house dust mite) are

reported (Figures 15.27–15.29).

 Bees, wasps, yellow jackets, hornets: dogs and cats:
Animal sensitivity and number of stings determine severity of reaction
Single stings result in localized pain, erythema, and severe edema
Anaphylactic shock can result
Stings occur most often on the muzzle and the extremities; if on the muzzle,

angioedema can result in respiratory compromise (Figure 15.30)

Some wasps, yellow jackets, and hornets can sting multiple times.

 Agitated behavior of dogs during an attack may stimulate further response from

Africanized bees and hornets.

 Severe attacks can result in death directly from the venom.

 Venom contains melittin and phospholipase A that act on cellular membranes causing

hemolysis, rhabdomyolysis, and kidney tubular necrosis.

DIFFERENTIAL DIAGNOSES

Flea Bite Dermatitis and Hypersensitivity

 Food allergy

 Atopy

 Sarcoptic/notoedric mange

 Cheyletiellosis