Equine Science Parasites

Question 0

Internal Parasites

Answer 0

 Roundworms – Ascarids/Parascaris Equorum  Bloodworms – Strongyles (large and small)
 Threadworms – Strongyloides Westeri
 Pinworms – Oxyruis Equi
 Bots – Gasterophilus
 Stomach Worms – Habronema
 Tapeworms – Anoplocephala

Question 1

General Signs of Parasite Infestation

Answer 1

 Weakness
Unthrifty/Pot-bellied appearance
 Emaciation/Weight loss
 Slow growth
 Rough hair coat
 Colic
 Coughing
 Lameness
 Slow wound healing

Question 2

Ascarids

Answer 2

Roundworms
 Common in young horses
 Older horses resistant
 Migrate, can damage heart, liver, lungs
 Can block small intestine
 Eggs can live in environment for years

Question 3

Large Strongyles

Answer 3

Bloodworms
 Very serious threat
 Not as big a risk now
 Travel through tissues
to lungs
 Aneurisms, blood clots
 Diminished blood flow

Question 4

Small strongyles

Answer 4

Bloodworms
More dangerous
Encysted 1-2 mo after return to intestine

Question 5

Oxyruis Equi

Answer 5

Pinworms
 Female attaches to anus to lay eggs
 Itching, tail rubbing
 Eggs very sticky, contaminate area rapidly

Question 6

Gasterophilus

Answer 6

Bots
 G. intestinalis (common)
 Eggs require stimulation
 G. nasalis (chin/throat)
 Eggs require stimulation
 G. hemorrhoidalis (nose)
 Do not require stimulation
 Adult is fly

Question 7

Habronema

Answer 7

Stomach Worms
Internal Cycle
 Larva deposited around mouth
by fly
 Matures in stomach
 Can cause colic
External Cycle
 Larva leave fly on wound instead of lips
 Unable to complete life cycle
 Can live like that for 6-24 mo

Question 8

Strongyloides Westeri

Answer 8

Threadworms
 Foals very susceptible (Infestation from dam)
Life cycle - 2 wk
 May cause ‘foal heat scours’
 Foals develop immunity after approximately 6 mo

Question 9

Anoplocephala

Answer 9

Tapeworms
 Requires an intermediate host
 Parasite absorbs nutrients through its skin
 Potential for intestinal damage and blockage

Question 10

External Parasites

Answer 10

 Ticks
 Lice
 Mites
 Chiggers
 Gnats
 Mosquitoes  Flies

Question 11

Ticks

Answer 11

Winter tick – northwestern US
 Widely distributed due to transportation
 Entire life cycle on horse
Pacific Coast tick – primarily coastal regions
 Adult drops off horse to lay eggs
 Larvae and nymph feed on small mammals
 Rocky Mtn Spotted Fever, African Horse . Fever (Piroplasmosis)
Spinose ear tick – southwestern US
 Larvae and nymphs are the problem

Question 12

Lice

Answer 12

host specific
Sucking Louse
 Feed on blood and tissue fluids
 Biting Louse
 Feed on skin and hair
 General
 Short life cycle
 Winter problem
 Easily transmitted