Applied equine parasitology

Question 1

What are signs of worm infestation?

Answer 1

Most horses tolerate worm burdens with little outward sign
Problems often only apparent when clinical disease imminent
Problems usually associated with high levels of infection

Question 2

What are risk factors for colic?

Answer 2

• No association with anthelmintic type / programme
• Increased risk if not on a worming programme
• Decreased risk if on a regular worming programme
• Increased risk after anthelmintic administration
• Strongylus vulgaris - thrombosis of cranial mesenteric artery + non-strangulating infarction

Question 3

What does cyathostominosis cause?

Answer 3

• Weight loss, hypoalbuminea
• Diarrhoea
• Intussusceptions – Caecocaecal
  – Caecocolic
• Can be associated with high mortality

Question 4

What can tapeworms cause?

Answer 4

Anoplocephala perfoliata infection associated with:

• Spasmodic colic
• Ileal impactions
• Caecal intussusceptions

Question 5

What are ascarids associated with?

Answer 5

• Large burdens of Parascaris equorum result in:
  – Weight loss / unthriftiness
  – Small intestinal obstruction & colic
• Can be associated with high mortality despite surgical intervention

Question 6

What are clinical significance of BOTS (Gastrophilus intestinalis)

Answer 6

• No clinical relevance

Question 7

How can you reduce need for anthelmintic treatment

Answer 7

• Appropriate stocking density

-Pasture management
* Faecal collection – at least twice a week
* Dung heaps separate from grazing areas
* Pasture rotation
* Grazing with ruminants

Question 8

How can you diagnose risk of strongyles?

Answer 8

• Strongyle faecal egg count

Question 9

How can you diagnose risk of tapeworms?

Answer 9

• FEC - centrifugation flotation (60% sensitive)
• ELISA
• EquiSal - saliva based test

Question 10

How can you diagnose risk of cyathostomins?

Answer 10

• Small redworm ELISA - detects all stages
• not recommended in low risk horses

Question 11

What worms are foals most likely to get first?

Answer 11

• Ascarids - Parascaris equorum

Question 12

What worms are more likely in yearlings?

Answer 12

• Strongyles + cyathostomins
• Tapeworms - Anoplocephala perfoliata

Question 13

What can Parascaris equorum cause?

Answer 13

• Migrating larvae cause respiratory disease
• Patent infection common cause of colic
   UK rates: animals <1yr prevalence = 38%
   Heavily contaminated pasture poses a risk

Question 14

What should be done for parasite control in youngstock 1-3y/o?

Answer 14

• FEC should be conducted more frequently
• Important to ensure efficacious drugs used
• FECRT
• Prioritise clearing of pastures on which youngstock are grazing - At least twice a week
• Grazing practices to reduce pasture contamination are very important in management of youngstock
• Use of diagnostics is important in youngstock
• FEC
• Tapeworm ELISA/Saliva test

Question 15

What should be done with parasites in adult horses?

Answer 15

• Small number of horses = producing most eggs = targeted treatment