ASC 382 Exam #3: Internal Parasites

Internal parasites

• small organisms that live a portion of their lifestyle in a horse host

• live in internal organs, cavities and tissues while gaining their nutritive source by feeding on the host animal

Strongyles

• adult form lives in the large intestine

• produce eggs that are passed out in the feces into the horse’s environment

• eggs develop into larvae that exist on pasture vegetation or in stalls

• larvae migrates which can cause blood clots that can disrupt blood flow to intestines and cause scar tissue formation in affected arteries

• lifecycle is 6-7 months

• eggs can withstand cold temps

Ascarids

• primarily infect young horses less than 2 years of age (adults develop immunity)

• cause damage to the animal at every developmental stage

• grass, feed, or water is contaminated with eggs and then consumed; larvae hatch and burrow into the small intestines

• migrate through veins to liver, heart, and eventually lungs

• physical damage: inflammation and scarring of liver and lung tissue, intestinal rupture, range from mild digestive upset to severe colic

Bots

• honey bee-sized flies

• three species: common, throat, nose

• female common: lays eggs on the hairs of forelegs

• female throat: lays eggs on long hairs beneath the jaw

• female nose: lay eggs on hair of upper and lower lips

• attach to stomach lining of horse and remain for about 7 months

• cause gastrointestinal issues