Parasites

Question 1

Parasites in horse

Answer 1

Gasterophilus - bots
Habronema
Parascaris equorum
Strongyloides westeri
Anoplocephala perfoliate magna
Dictyocaulus arnfieldi
Strogylus vulagaris
Strongylus equinus
Strongylus edentatus
Small strongyles - cyathostominosis
Oxyuris equi

Question 2

Small strongyles

Answer 2

Small and red/white
Large intestines

Clinical signs
illthrift
Colic
D+
Hypoalbuminaemia
Weight loss
Severe SIRS
death

Question 3

Large strongyles

Answer 3

S. vulgaris
S. equinus
S. edentatus
Small and red/white
Large intestines

Clinical signs
illthrift
Blood vessel wall damage, haemorrhage and infarction - s. vulgaris

Question 4

Round worms

Answer 4

Parascaris equorum
Large fat and white
Small intestines

Clinical signs
illthrift
colic - SI obstruction
Cough

Question 5

Pin worm

Answer 5

Oxyuris equi
5cm, beansprout
Rectum

Clinical signs
Itchy perineum

Question 6

Tapeworm

Answer 6

Small, flat, white
Ileocaecal area
Small intestine

Clinical signs
illthrift
Colic

Question 7

Habronemiasis

Answer 7

Skin sores - summer sores
Conjunctivitis
Adult worms live and reproduce in stomach
If deposited in conjunctiva or wounds - will not migrate - local disease
All ages
June - September

Fly control
Frequent bedding change
Removal of droppings from paddock
Cover wounds and treat ocular disease
Will be killed in horse worming for other parasites
- Avermectins/benzomidazoles to lesser extent

Question 8

Parascaris equorum

Answer 8

Equine round worm
Disease of younger animals - immunity by two years
Common
10cm
Emerging resistance

Migration through liver, vena cava, alveoli, bronchi, trachea - eggs coughed up and swallowed
Reservoirs - adult horses shed in small numbers but infect youngstock
Fouls not infected in utero or milk

Clinical signs
Coughing and nasal discharge
Poor coat and poor weight gain
Dull, anorexic, colic - bowel obstruction

Disorders of bone and tendons as nutrient competition
Distinct eggs - round and lumpy - raisin - durable

Treatment
Pyrantel

Question 9

Tapeworm - anoplocephala perfoliata/magna

Answer 9

Any age, young
Suck to intestinal mucosa
High prevalence

Colic
- ileal impaction
- Intussusception
- Impactions and motiliy disorders
- Spasmodic
- Diarrhoea

Indirect life cycle - eggs released and infective to oribatid mite
6-10 week pre patent period
Ingest in spring
Test every 6 months - salivary test

Treat
Praziquantel in autumn/winter
Stable for 48 hours after worming

Question 10

Strongylus vulgaris

Answer 10

Most clinically important large strongyle
Surgical colic from larvae
Some immunity
Young/unexposed - most severe disease
All ages, worse in yearlings
Reservoirs - asymptomatic animals shedding large numbers of eggs

Diagnosis
pre patent disease
May feel thrombi when rectalling
faecal analysis - not always good and cannot tell from other strongyles
No correlation between egg count and luminal worm count

On pasture spring/summer - disease autumn/winter - in arteries
Adults - protein losing enteropathy and anaemia
Colic, diarrhoea, anorexia
Ischaemic, dying gut - resect gut
Aorto iliac junction - lameness and poor performance
Can migrate to brain, kidney, lungs, liver - granulomas

Treatment
Benzomidazoles and avermectins - larvae and adults
avoid overgrazing - eggs on ground
poo pick
Pyrantel - adults only

Question 11

Strongylus edentatus and equinus

Answer 11

Edentatus - colic due to liver disease or peritonitis
Equinus - mild colic - some association wiht pancreatic disease and diabetes mellitus
Diagnosis - faecal egg count

Question 12

Cyathostominosis

Answer 12

Severe acute diarrhoea and colic, chronic diarrhoea
Encysted unaffected by anthelmintic - moxidectin poor rates but best we have
Larvae emerge in spring
Most larvae on pasture in autumn

Diagnosis
Difficult as PPP disease
History and clinical signs - poor worming history
Larvae in faeces or on rectal glove with acute cyathostominosis

Due to mucosal damage caused by emergence of the late L3
Colic
Weight loss
Diarrhoea – acute and chronic
Wasting and death either acutely or chronically

Question 13

When is cyathostominosis seen?

Answer 13

Emergence in spring

Can see in autumn - when entering intestinal wall
- Colic
- Diarrhoea

Question 14

What is Oxyuris. equi

Answer 14

Equine pin worm

Question 15

Oxyuris equi

Age?
Stabled or pasture?
Reservoirs?
Clinical signs
How to test?

Answer 15

Affect any age
Parasite of stabled horses – eggs don’t survive well outdoor
Reservoirs – other infected horses and immediate environment
Anal pruritus and skin excoriation and/or myiasis
Eggs in the perianal region on examination
Sellotape test – put on slide and examine under the microscope

Question 16

Oxyuris equi treatment

Answer 16

All anthelmintics should be effective – some resistance
Anal application as a paste

Can use topical or systemic anti-inflammatories to decrease pruritus and keep area clean with disposable material

Good stable hygiene – water troughs, mangers etc

Question 17

Cyathostominosis treatment

Answer 17

moxidectin

Question 18

How to treat colic due to high parascaris burden?

Answer 18

pyrantel

Question 19

How to treat recurrent colic and high ELISA for anaplocephala?

Answer 19

Praziquantel or double dose pyrantel

Question 20

How to prevent cyathostominosis

Answer 20

Appropriate stocking
Faecal collection
Minimum of twice weekly
Larvae do not stay in faeces
Dung heaps separate from grazing area
Pasture rotation
Best in hot dry condition as larvae overwinter in mild winters
Grazing with ruminants

Question 21

Which horses do we parasite treat?

Answer 21

Must be a yard wide approach
Treat if faecal WEC > 250epg (Based on testing every 8-12 weeks throughout the grazing season) with ivermectin or pyrantel

Perform a faecal egg count reduction test after 14 days to assess efficacy of treatment

Treat new arrivals at yard and hold away from turn out for a minimum of 3 days (or ideally until FWEC reduction) is assessed
For young horses WEC are required more frequently