240 DISEASES/DISORDERS
FBD: caused by direct irritation at the site of bites.
FBH: caused by immediate (type I), delayed (type IV), and cutaneous basophil hyper-
sensitivities.
Flea saliva contains histamine-like compounds, several complete allergens, and hap-
tens that bind to form complete antigens.
Spider Bite Dermatitis
Medically important species include the common brown spider (Loxosceles unicolor),
brown recluse (Loxosceles reclusa), black widow (Latrodectus mactans), and red-legged
widow (Latrodectus bishopi).Bites ofLoxoscelesspp. produce localized tissue necrosis.
Bites ofLatrodectusspp. are more likely to produce systemic reactions.
Spider bites occur most often on the face and forelegs.
Fly Dermatitis
Flies can create significant dermatitis by direct damage to intact skin and subsequent
irritation (fly dermatitis).
Fly strike (myiasis) is a distinct and separate dermatitis caused by laying of eggs by
dipterous flies on warm, wet skin, and subsequent larval (maggot) invasion of tissues.
Most often caused by bites from stable flies (Stomoxys calcitrans) and black flies
(Simuliumspp.).
May also be caused by horseflies and deerflies (TabanusandChrysopsspp.).
Mosquito Bite Dermatitis and Hypersensitivity
The hair coat usually protects dogs and cats from mosquito and gnat bites (Culicoides
spp.).
Dogs and cats can be irritated by mosquito bites.
A distinct syndrome of mosquito bite hypersensitivity has been documented in cats.
Tick Bite Dermatitis and Hypersensitivity
Dogs and cats can be irritated by tick bites.
Ticks are vectors for bacterial, rickettsial, protozoal, and viral infections.
Ticks are the cause of tick paralysis.
Most dogs fail to demonstrate a delayed-type hypersensitivity.
Seasonal incidence: warm weather; May through July.
Ear ticks infest the ear canal, producing symptoms of otitis externa.
Hymenoptera Sting
Order includes ants, bees, wasps, yellow jackets, and hornets.
Only a few species of ants cause venomous reactions.
Bees and some wasps die after a single sting; other hymenoptera can sting multiple
times.