6 Flashcards
Tapeworm. The most common tapeworm in horses is in the genus
Anoplocephala.
, is called the “large horse tapeworm” and occurs most often in the
small intestine. It also is found in the stomach and sometimes in the cecum.
Anoplocephala magna
Stomach Worms
The habronemas, which consist of
consist of Habronema muscae, H. majus, and H. megastoma (Draschia
megastoma), are the equine stomach worms
equine stomach worms that cause two rather distinct diseases in horses:
gastric and
cutaneous habronemiasis
have indirect life cycles, with house and stable flies serving as
intermediate hosts.
Habronemas
is the horse ascarid.
Parascaris equorum
is the horse ascarid.
Parascaris equorum
is the horse ascarid.
Parascaris equorum
Horses, like people and unlike dogs, can have pinworms. Two kinds of pinworms occur in horses.
A rather large one, the females of which can be up to 63 millimeters long, is_________________The minute
horse pinworm, ____________ is only about 2 millimeters long and is of little consequence.
Oxyuris equi.
Probstmayria sp.
is a protozoan disease occurring in horses, mules,
and donkeys.
Equine piroplasmosis, or equine babesiosis,
Two species of Babesia
B. caballi and B. equi
The tropical horse tick
(Dermacentor nitens) serves as intermediate host
The brown dog tick__________ may be able to serve as an intermediate host for B. equi..
_(Rhipicephulus sanguineus)
probably occurs throughout North America, affecting male and female horses equally.
Thoroughbreds and Standardbreds are affected more frequently. Signs can appear at any age, but most
cases occur in horses under 4 years old.
Equine Protozoal Myeloencephalitis (EPM)
probably occurs throughout North America, affecting male and female horses equally.
Thoroughbreds and Standardbreds are affected more frequently. Signs can appear at any age, but most
cases occur in horses under 4 years old.
Equine Protozoal Myeloencephalitis (EPM)
Most likely the protozoan ___________________ causes
EPM
Sarcocystis neurona
Most likely the protozoan ___________________ causes
EPM
Sarcocystis neurona
species are nematodes that occur as adults in connective tissue of horses, mules, and
donkeys. They are fairly common parasites.
Onchocerca species
, is about 19 millimeters long and lives in the tear duct
and conjunctival sac of the horse’s eye.
Thelazia lacrymalis
develops in the eye and causes damage.
Normally, these nematode parasites, which use mosquitoes as intermediate hosts, occursin the abdominal
cavity and are of little or no consequence.
Setaria equina
External parasites of horses include
ticks, mites, chiggers, and lice
The winter tick,_____________has become widely distributed because horses now are
commonly transported from one part of the country to another. Although this tick occurs primarily on
the horse, it is found on other farm animals, such as cattle, sheep, and goats, so these animals can also be
involved in its spread.
Dermacentor albipictus
The Pacific coast tick,____________________ is found chiefly
in coastal areas of the West. Unlike the winter tick, this tick drops off the
host to lay its eggs, and the larvae and nymphs feed on small mammals
before becoming adults and parasitizing horses.
Dennacentor occidentalis
The ear tick, _________________like Dermacentor albipictus, is a one-host tick. It is common on
horses but is also found in the ears of cattle, sheep, dogs, cats, and, occasionally, people. These ticks,
however, do not occur on the horse in their adult stage: only the larvae and nymphs are found in the
horse’s ears. Adults have nonfunctional mouth parts but may survive for 2 years on the ground.
Otobius megnini
are ectoparasites that are closely related to ticks and cause a skin condition called mange.
The entire life cycle of mange mites occurs on the horse. Mating occurs on the skin or in burrows the
mites make in the skin. The eggs hatch on the host after about 4 days and are mature, egg-laying adults
12 to 15 days later.
Mites
causes lesions usually found on the
neck, shoulders, head, chest, and flanks of horses. These mites burrow
under the skin and cause severe irritation and itching.
Sarcoptic mange (Sarcoptes)
produces lesions like sarcoptic
mange, but since the mites occur more commonly on the lower
extremities, it often is called foot mange.
Chorioptic mange (Chorioptes)
occurs primarily on the poll or the tail. This mange mite (Psoroptes) also causes
intense itching, with hair loss and scabs if the horse traumatizes itself extensively.
Mange mites can live off the host for a short time and can be transferred from one host to another
on combs, blankets, and so forth. In the past, mange has been extremely difficult to control; but with the
new ivermectins, mange should become a less-se1ious problem.
Psoroptic mange
occurs primarily on the poll or the tail. This mange mite (Psoroptes) also causes
intense itching, with hair loss and scabs if the horse traumatizes itself extensively.
Mange mites can live off the host for a short time and can be transferred from one host to another
on combs, blankets, and so forth. In the past, mange has been extremely difficult to control; but with the
new ivermectins, mange should become a less-se1ious problem.
Psoroptic mange
_________affect horses in much the same way they affect people. _________
are the larval stage of harvest mites (Trombicula) that affect horses’ feet and
muzzles as they walk and feed on infested pastures.
Chiggers
Lice can be a very serious problem in horses. There are two kinds of lice:
biting lice (Damalinia), which feed on skin and hair, and sucking lice
(Haematopinus), which pierce the skin and suck blood and tissue fluids
very often cause
intense itching and attendant lesions in horses’ ears, although they will bite other thin-skinned areas of
the horse as well.
Black flies and “no-see-ums”
are fly larvae that are parasites in the stomach of horses.
Bot
are the two common botflies found in this country.
Gastrophilus intestinalis, the
common horse bot, and
G. nasalis, the throat botfly
