Other parasites of horses

Question 1

What are nematodes of horses?

Answer 1

*Parascaris equorum
*Oxyuris equi
*Dictyocaulus arnfieldi

Question 2

What are ectoparasites of horses?

Answer 2

*Lice
*Chorioptes
*Bots - gastrophilus
*Sweet itch - culicoides

Question 3

What are tapeworms of horses?

Answer 3

*Anoplocephala perfoliata
*A. magna
*Paranplocephala mamillana

Question 4

What are trematodes of horses?

Answer 4

*Fasciola hepatica

Question 5

What is the intermediate host of Horse tapeworms?

Answer 5

*Oribatid mite

Question 6

What is the metacestode stage found in the oribatid mite?

Answer 6

Cysticercoid

Question 7

What are identifying characteristics of Anoplocephala perfoliata

Answer 7

*Lappets behind each of four suckers

Question 8

Where are tapeworms found in horses?

Answer 8

Ileo-caecal junction

Question 9

What is the life cycle of Anoplocephala perfoliata?

Answer 9

1. Infected mite ingested by horse
2. 2 months post-ingestion = adult tapeworm at ileo-caecal junction
3. Proglottids passed in faeces, disintegrate and eggs released
4. Oribatid mites ingest eggs = cysticercoid

Question 10

What do Anoplocephala perfoliata eggs look like?

Answer 10

*Eggs = D-shaped
*50-80um

Question 11

What can tapeworms cause in horses?

Answer 11

*Spasmodic colic
*Intussuseption
*Ileal impaction
*Rupture

Question 12

What is the head of a tapeworm called?

Answer 12

Scolex

Question 13

What are clinical signs of tapeworms in horses?

Answer 13

*Ulceration + pathological change in intestine
*Unthriftiness
*Enteritis
*Colic

Question 14

When do tapeworm infections peak?

Answer 14

Autumn / Winter

Question 15

How are tapeworms diagnosed?

Answer 15

*Eggs in faeces
*ELISA to detect antigen
*EquiSal saliva test

Question 16

How would you treat tapeworm?

Answer 16

*Double dose of Pyrantel
*Praziquantel

Question 17

What are general features of ascarid nematodes in horses?

Answer 17

• Females lay huge numbers of eggs
• Eggs are highly resistant
• L2 larvae develop in the egg
• L2 in egg is the infective stage
• Direct life cycle
  *Hepato-tracheal migration

Question 18

What can migrating larvae cause? What do adult ascarid worms do?

Answer 18

*Migrating larvae = stimulate inflammatory response
*Adults = compete for nutrients in intestines
*Adult worms can cause mechanical blockage due to size
**NO damage to mucosa

Question 19

What is the life cycle of Parascaris equorum?

Answer 19

1. Eggs in faeces - develop on ground - temp dependent (4wks)
2. Egg (L2) eaten by horse
3. L2 migrates to liver, lung (L2-L3)
4. L4 / L5 coughed up and swallowed in SI
   PPP = 12weeks

Question 20

What does parascaris equorum infection cause?

Answer 20

*Affects foals
*Transient cough
*Poor weight gain
*Unthrifty

Question 21

How does ascarid infection spread? How is this prevented?

Answer 21

*Foal to foal - adults immune
*Anthelmintic tx

Question 22

What is Oxyuris equi also known as? Where is it found?

Answer 22

Horse Pinworm - Large intestine

Question 23

What are features of oxyuris equi?

Answer 23

*Adults have pointed tails
*1-10cm
*Eggs = 80um + oval - more pointed ends than strongyle

Question 24

What is the life cycle of oxyuris equi?

Answer 24

1.Female lays eggs on peri-anal skin - eggs fall to ground
2. Develop to L3 in egg on ground
3. Ingested by horse - larvae develop in mucosal crypts in large intestine
4. Adults in lumen of large intestines
PPP = 5 months

Question 25

What are clinical signs of oxyuris equi infection?

Answer 25

*Pruritus
*Excoriation of tail (damage to skin)

Question 26

How is oxyuris equi infection diagnosed?

Answer 26

*Eggs on peri-anal area
*Sellotape / scotchtape test