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Disease Information

For further information on any of these common UK diseases of horses, just click on one of the entries from the list below.

Small Redworms (Cyathostomum spp.)

Symptoms
Ill-thrift, diarrhoea, reduced performance, weight loss, death.

Significance
Commonly comprise more than 90% of the horse's worm population and are the most common parasites.

Diagnostic
Faecal egg counts in summer.

Control
Through implementation of a comprehensive parasite control programme.

Treatment programmes
Use of EQVALAN every 8-10 weeks (plus a treatment to kill encysted inhibited stages in February if necessary, your vet can advise).

Life cycle
5-18 weeks.

Description of parasite
Small worms 0.4 - 0.6cm long, greyish white in colour but appear red after feeding.

Location in body
Large intestine.

Large Redworms (Strongylus spp.)

Symptoms
Ill-thrift, diarrhoea, reduced performance, weight loss, colic, thromboembolism.

Species
Strongylus vulgaris, Triodontophorus spp., Strongylus edentatus, Strongylus equinus.

Significance
Not common but potentially very dangerous.

Diagnostics
Faecal egg counts.

Control
Through implementation of a comprehensive parasite control programme.

Treatment programmes
Use of EQVALAN every 8-10 weeks.

Life cycle
6-11 months.

Description of parasite
2-5 cm long, and feed off intestinal lining.

Location in body
Gut wall, mesenteric artery.

Lungworm (Dictyocaulus arnfieldi)

Symptoms
Ill thrift, weight loss, respiratory problems and persistent cough in adult horses and donkeys (the principal source of infection in horses).  Foals do not usually show any signs of infection.

Species
Dictyocaulus arnfieldi.

Diagnostics
Faecal egg counts.

Control
Through implementation of a comprehensive parasite control programme.

Treatment programmes
Use of EQVALAN every 8-10 weeks.

Life cycle
2-4 months.

Location in body
Lungs.

Pinworm (Oxyuris equi)

Symptoms
Scratching, rubbing around anal region.

Species
Oxyuris equi.

Diagnostics
Faecal egg counts.

Control
Through implementation of a comprehensive parasite control programme.

Treatment programmes
Use of EQVALAN every 8-10 weeks.

Life cycle
4-5 months.

Description of parasite
Females can be up to 10 cm long and lay their eggs around the outside of the anus.

Location in body
Large intestine and rectum with eggs, around anus.

Threadworms (Strongyloides westeri)

Symptoms
Diarrhoea, loss of appetite, anaemia and dullness.

Species
Strongyloides westeri.

Significance
Only affect young foals, natural immunity develops by around 6 months of age.

Diagnostics
Faecal egg counts.

Control
Targeted treatment of foals. 

Treatment programmes
Use of EQVALAN every 8-10 weeks.

Life cycle
8-14 days.

Description of parasite
Very small worms which live in the small intestine of young foals.

Location in body
Small intestine.

Large Roundworm (Parascaris equorum)

Symptoms
Ill-thrift, stunted growth, digestive problems (adult worms), ruptured gut, death. 'Summer colds' can be caused by larval stages in the lungs.

Species
Parascaris equorum.

Significance
Only affect foals and young horses, immunity to these worms develops at about 18 months.

Diagnostics
Faecal egg counts.

Control
Through implementation of a comprehensive parasite control programme.

Treatment programmes
Use of EQVALAN every 8-10 weeks or every 4-6 weeks in foals if there is a heavy burden.

Life cycle
10-12 months.

Description of parasite
The largest parasite, reaching up to 50 cm in length.

Location in body
Small intestine.

Bots (Gastrophilus spp.)

Species
Gastrophilus intestinalis, Gastrophilus nasalis, Gastrophilus haemorrhoidalis, Gastrophilus pecorum.

Significance
The most common parasite of the stomach, adult stages are horse bot flies, which cause distress and annoyance to grazing horses in summer months.

Diagnostics
Gastroscopy - visualising them in the stomach, bot eggs on legs and faces of horses in summer months.

Control
Through implementation of a comprehensive parasite control programme.

Treatment programmes
Routine worming with EQVALAN during summer months and treatment after first frosts.

Life cycle
One generation per year.

Description of parasite
Insect larvae of horse bot flies.

Location in body
Immature stages in the stomach.

 

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