Equine Endoparasites

Question 1

Name three cestodes of horses

Answer 1

Anoplocephala perfoliata

A. Magna

Paranplocephala mamillana

Question 2

Name the intermediate host of cestodes.

Answer 2

Oribatid mite

Question 3

Describe the lifecycle of A. perfoliata.

Answer 3

• Infected mite ingested by the horse
• After 2 months adult worms are present at the ileo-caecal junction
• Proglottids gravid with eggs are passed in horses faeces
• Proglottids disintegrate and release eggs which are ingested by oribatid mite
• Eggs develop within the mite to cysticercoid
• Mites are found in soil, shavings and hay (and are v small)

Question 4

Describe the morphology of A. perfoliata eggs.

Answer 4

D-dhaped

~50-80 um

Onchosphere is supported by pyriform apparatus

Question 5

Describe the morphology of adult A. perfoliata.

Where in the equine SI are they found?

Answer 5

• Short broad segments
• Lappets behind each four suckers
• Adults are found at the ileo-caecal junction

Question 6

What are the clinical signs associated with A. perfoliata infection?

What associated condtions?

Answer 6

C/S

• Ulceration of intestine
• Ill thrift
• Enteritis

Associated conditions:

• Spasmodic colic
• Itussuscpetion
• Ileal impaction/ rupture

Question 7

What ages are most affected by A. perfoliata?

Which time of year is most associated with A. perfoliata infection?

Answer 7

• Less than three have highest level of infection but all ages are affected.
• Autumn/ winter are peak levels but all times of year are possible.

Question 8

How is A. perfoliata infection diagnosed in the horse?

Answer 8

• FEC (only around 60% sensitivity)
• ELISA detects Ag (95% specificity)
  
  • Parasite excretory/secretory Ag
  • IgG

Question 9

Describe a treatment plan for A. perfoliata infection.

Answer 9

Double dose pyrantel

Praziquantel

Question 10

Giant roundworm

aka

Answer 10

Ascarids

Question 11

Which stage of the ascarid lifecycle is infective?

Answer 11

L2 found within the egg

Question 12

True or False.

Ascarid eggs are highly resistent to death outside the host.

Answer 12

True

Question 13

Where in the horse can Ascarids be found?

(x2)

What are the potential effects of the infection?

Answer 13

• Small intestine
  
  • Compete with horse for nutrients
  • May cause mechanical blockage
• Migrating - hepato-tracheal migration
  
  • Stimulates ++ inflamm response

Question 14

Describe the morphology of a Parascaris equorum egg.

Answer 14

Round and thick walled with undiff morula in the centre.

Question 15

Outline the lifecycle of Parascaris equorum.

Answer 15

• Eggs are passed onto pasture
• L2 develops within the egg (takes about 4 weeks but is temp dependent)
• Egg is eaten by the horse
• L2 migrates to the liver and then lung, developing to L3
• L3 is coughed up and reswallowed, develops from L4-L5 in the SI

Question 16

PPP

Answer 16

The period of time from infection until mature adult parasites are producing eggs or larvae.

Question 17

What is the PPP of Parascaris equorum?

Answer 17

Around 12 weeks

Question 18

What clinical signs are associated with Parascaris equorum?

Answer 18

• Typically foal infection
  
  • foals can spread to other foals but adults are generally immune
• Transient cough
• Ill thrift and poor wt gain
• XX diarrhoea
• GI obstruction in heavily infected animals

Question 19

How can Parascaris equorum be controlled in the horse?

Resistence to which anthelmintic has been reported?

Answer 19

Anthelmintics and pasture rotation (remember wggs are very resistent)

Ivermectin resistence

Question 20

Describe the morphology of Oxyuris equi eggs and adult.

Answer 20

1. Egg: 80um, oval shaped with a slightly pointed edge
2. Adult: 1-10cm with a pointed tail

Question 21

In which part of the equine GI tract would Oxyuris equi be found?

Answer 21

Large intestine

Question 22

Outline the lifecycle of Oxyuris equi.

Answer 22

1. Female lays eggs on the perianal skin
2. Eggs fall on the ground
3. L3 develop in the egg
4. L3 ingested and develop in the LI mucosal crypts
5. Adults present in the LI lumen

Question 23

What is the PPP of Oxyuris equi?

Answer 23

5 months

Question 24

Anal rust and pruritis are associated with which equine parasite?

Answer 24

Oxyuris equi

Question 25

How can Oxyuris equi be diagnosed and treated?

Answer 25

Selotape test on perianal area Anthelmintics though limited efficacy

Question 26

What is meant by a extraneous parasite? Name two examples in the horse.

Answer 26

Of little consquence.. Triodontophorus spp and Trichostrongylus axei

Question 27

Pathogenesis of extraneous parasites? Describe the morphology of their eggs?

Answer 27

* Contribute to the damage caused by adult worms of other species * Feed in groups Eggs are similar to other strongyles but twice the size