Oxyurosis of horses

Question 1

What is the common name for Oxyuris spp.?

Answer 1

Pinworms

Question 2

What species are primarily affected by Oxyuris equi?

Answer 2

Horse & donkey

Question 3

In which part of the body does Oxyuris equi reside?

Answer 3

Large intestine

Question 4

Describe the morphology of Oxyuris equi.

Answer 4

Females are slender with a sharp-pointed posterior end, large oesophageal bulb, swollen cuticle in anterior part

• Male: 1cm
• Female: 5-15cm

Pinworms are common among birds, mammals, reptiles and amphibians.

Question 5

What is the size difference between male and female Oxyuris equi?

Answer 5

Males are 1 cm; females are 5-15 cm

Question 6

What is the appearance of Oxyuris equi eggs?

Answer 6

• Medium
• Ovoid - asymmetrical
• 2 thin shells, mucoid cap
• Unembryonated
• Yellow-brown

Question 7

What type of life cycle does Oxyuris equi have?

Answer 7

Direct life cycle

1. Larvae (L3) hatch in the small intestine, pass into the large intestine and enter the mucosal crypts of cecum and colon.
2. They moult into L4 (8-10 days). Moulting to adults (45-60 days) happens, and then the adult becomes longer before it can be fertilized.
3. After fertilization, the gravid female migrates to the anus and lays eggs in clumps in a yellowish-grey gelatinous material on the perineal skin. They release 8000-60 000 eggs. Development to the L3 (infective stage) takes place inside the egg and is very fast (3-5 days). L3 is then eaten again on the feed of the horse.

Question 8

Where do larvae (L3) of Oxyuris equi hatch and develop?

Answer 8

In the small intestine, then pass into the large intestine and enter mucosal crypts of cecum and colon

Question 9

How long does it take for Oxyuris equi to moult to adults after hatching?

Answer 9

45-60 days

Question 10

How many eggs can a gravid female Oxyuris equi lay?

Answer 10

8000-60,000 eggs daily

Question 11

What is the infective stage of Oxyuris equi?

Answer 11

Egg with L3

Question 12

How does L4 of Oxyuris equi feed?

Answer 12

By ingesting intestinal mucosa

Question 13

What are some clinical signs of Oxyuris equi infection?

Answer 13

• Anal/rectal pruritus
• Broken hair/bare patches & inflamed skin on rump and tail head
• Restless animals
• Inappetance
• Loss of condition

Question 14

What is a common treatment for Oxyuris equi?

Answer 14

Mebendazole, febantel, ivermectin

Wash perineum with soap to remove eggs

Question 15

What hygiene practices are recommended for controlling Oxyuris equi?

Answer 15

• Clean stables, feeding ranks and water troughs
• Frequent removal of bedding

Question 16

What methods are used for diagnosing Oxyuris equi?

Answer 16

Clinical signs, coprological examination (fecal examination) with perianal swab

Question 17

True or False: Oxyuris equi is found worldwide.

Answer 17

True

Question 18

Epidemiology of Oxyuris equi

Answer 18

Flakes of material containing eggs are spread throughout the environment when the animal rubs against fences, stable fittings, other solid objects.
Little immunity to reinfection.

Question 19

Pathogenesis of Oxyuris equi

Answer 19

L4 have a large buccal capsule and they feed by ingesting intestinal mucosa. This causes mucosal erosions.
Adult worms live freely in the intestinal lumen feeding on gut.