Other Equine Parasites

Question 1

What cestodes affect horses?

Answer 1

Anoplocephala perforliata
Anocephala magne
Paranplocephala mamillana

Question 2

What are the characteristics of tapeworms?

Answer 2

Adult parasites found in small intestines

Indirect life cycle- in this case involves an oribatid mite (free living forage mite) as the intermediate host

Metacestode stage found in the intermediate host is a cysticercoid

Question 3

What is the most common, significant species of tapeworm?

Answer 3

Anocephala perfoliata

Question 4

Describe the appearance of anocephala perforliata?

Answer 4

Adults found at the ileo-caecal junction

Short, broad segments

Lappets behind each of four suckers

Question 5

How can you distinguish between A. perforliata, A. Magna and P. mamillana?

Answer 5

A. perforliata- lappets behind each of four suckers

A. magna- no lappets

P. mamillana- two suckers

Question 6

Describe the life cycle of A. perforliata

Answer 6

• Adult tapeworm at ileo-caecal junction
• Proglottids passed in faeces, disintegrate and eggs release
• Eggs ingested by free-living orbatid mites and develop to cysticercoid
• Infected mite ingested by horse
• 2 months from ingestion of mite to presence of tapeworm

Question 7

Where are orbitatid mites- carriers of cysticeroids of A. perforliata found?

Answer 7

Found in soil, shavings, hay

Common, ubiquitous

Microscopic

Question 8

What does this image show?

Answer 8

Egg of A. perfoliata (right) compared to a strongyle egg (left)

Eggs of A. perfoliata irregularly shaped (D-shaped)

Oncoshpere supported by pyriform apparatus

Question 9

Describe the pathogenesis of A. perfoliata

Answer 9

Adults at the ileo-caecal junction

Causes-

Spasmodic colic, intussusception, ileal impaction, rupture

Question 10

What are the clinical signs of A. perfoliata infection?

Answer 10

Ulceration and pathological changes in intestine

Unthriftiness

Enteritis

Colic

Question 11

What ages of horse are affected by A. perfoliata and when does the infection level peak?

Answer 11

All ages infected- highest in <3yo

Peaks in autumn/winter- always possible

Question 12

How is A. perfoliata diagnosed and controlled?

Answer 12

Eggs in faeces- FEC

ELISA for circulating antigen- IgG

EquiSal saliva test

Treatment/control- Double dose pyrantel, Praziquantel

Question 14

What families of nematodes affect horses?

Answer 14

Stronglyes

Parascaris equorum

Oxyuris equi

Question 15

Describe the general appearence and location of ascarid nematodes?

Answer 15

Large, white roundworms

Adults in small intestine

Question 16

What are the general features of ascarid nematodes?

Answer 16

• Females lay large numbers of eggs
• Eggs are highly resistant
• L2 larvae develop in egg
• L2 in egg is infective stage
• Direct life cycle
• Hepato-tracheal migration
• Migrating larvae stimulate inflammatory response
• Adult worms browse on intestinal contents
• Adult worms can cause blockage
• No damage to mucosa

Question 17

What species of ascarid nematodes affects horses and donkeys and describe their life cycle

Answer 17

Parascaris equorum-

Eggs passed in faces
Develop on ground- temp dependent
Egg containing L2 eaten
L2 migrates to liver- lung- L2-L3
Coughed up, swallowed, L4-L5 in SI

PPP- 12 weeks

Question 18

What age of horse does Parascaris equorum affect and what are the symptoms?

Answer 18

Typically foals

Transient cough
Poor weight gain
No diarrhoea
Possible obstruction in heavily infected individuals

Question 19

How is Parascaris equorum (carbonara) controlled?

Answer 19

Foal to foal infection- adults immune

Eggs resistant- anthelmintic resistance

Drug resistance reported to- Ivermectin and moxidectin

Question 20

What parasite and egg is shown in this image?

What is its name and common name?

Answer 20

Oxyuris equi

Horse pinworm

Question 21

Describe the appearance of oxyuris equi and what is an infection commonly refered to as?

Answer 21

Adult worms are 1-10 com and have pointed tails

‘Anal rust’

Question 22

Describe the life cycle of Oxyuris equi and what is the PPP?

Answer 22

• Direct
• Female lay eggs on peri-anal skin
• Eggs fall to ground
  Develop to L3 in egg
• Ingested
• Larve develop in mucosap crytpes in LI
• Adults in lumen of LI

PPP- 5 months

Question 23

Oxyuris equi- What are the clinical signs, how is it diagnosed and controlled?

Answer 23

Clinical signs- prutitis, excoration (tail) [urge to constantly itch]

Diagnosis- eggs on peri-anal area, sellotape test

Control-
Anthelmintics- but can be a challenge due to lack of efficacy/rapid reinfecton
High hyigene environments reduces transmission