Equine Parasites

parasites of horse

-habronema

-parascaris equorum

-anoplocephala perfoliate/magna

-stronglus vulgaris

-strongylus equinus

-strongylus edentatus

-small strongyles (cyathostominosis)

-oxyuris equi

check the table all done

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small strongules shape, predeliction site

-small and red or white

-large intestine

clinical signs of small strongyles

-ill thrift

-colic

-D+++

-hypoalbuminaemia

-weight loss

-severe SIRS

-death

shape and predeliction site of large strongyles

-bit bigger than small strongyles but still small

-red or white

-large intestine

clinical signs of large strongyles

-ill thrift

strongyles vulgaris symptom that other strongyle don't have

blood vessel wall damage, haemorrhage and infarction

shape and predeliction site of parascaris equorum (round worm)

-large fat and white

-small intestine

clinical signs of parascaris equorum

-ill thrift

-colic when in large numbers as cause obstruction

-cough

shape and predeliction site of oxyuris equi (pinworm)

-white pointy tail like beansprout

-rectum

clinical signs of oxyuris equi

itchy bottom

shape and predeliction site of anoplocephala magnum and perfoliata (tapeworm)

-small flat white, look like someone stood on them

-iliocaecal area (perfoliate) or small intestine (magna)

clinical signs of anoplocephala perfolitata and magna

-ill thrift

-colic

habronema signs

-skin sores

-occ conjunctivitis

where do adult worms of habronema live

stomach

if habronema in conjunctiva or wounds means what

cannot migrate

seasonality of habronema

between june to september

how is habronema spread

flies

if habronema in stomach, signs

-mostly no disease

-can cause nodules of granulation tissue which contain eosinophils

diagnosis of habronema

-hard to diagnose on faecal analysis as eggs very fragile and rupture

-gastric lesions with gastroscopy

prevention of habronema

-fly control and much heap management

-replcing bedding a lot

-collecting and removing droppings

-cover wounds and treat ocular disease causing ocular discharge

-killed in horse with worming for other parasites

wormer not effective on habronema

avermectins and benzimidazoles

parascris equorum

ascarid

what age does parascaris equorum affect

-horses less than 2 years old

-immune response more developed in older animals

why is parascaris equorum up and coming

emerging resistance

life cycle of parascaris equorum

-migration through liver, vena cava, alveoli, bronchi, trachea so eggs coughed up and swallowed

reservoirs for parascaris equorum

adult horses

-small numbers but shed enough eggs to infect foals or young stock

how is parascaris equorum transmitted to foals

-NOT infected in utero or via milk

-from pasture

clinical signs of parascaris equorum

-coughing and nasal discharge when parasites in lungs

-poor coat

-weight gain

-dull

-anorexic

-colicking inc bowel obstruction→ bc worms os big

-disorder of bone and tendons as parasites consume a lot of Ca, P, Zn, Cu

diagnosis of parascaris equorum

difficult but very distinct eggs when present

• brown, thick shell,

treatment of parascaris equorum

-resistance to avermectins

-drug rotation does not prevent resistance

-can see colic if treats lots of adult worms with paralytic drugs

PYRANTEL

anoplocephala perfoliata/magna

equine tapeworm

what horses does a. magna and perfoliata affect

usually young but can be any age

how does a perfoliata and magna look

no hooks but very large suckers that attach to intestinal mucosa

a.perfoliata clinical signs

colic

-ileal impaction

-intussusception

-caecal impactions and mobility disorder

-spasmodic colic

-diarrhoea

-functional and physical blockages

type of lifecycle of a. perfoliata

indirect- has mite

a perfoliata shedding

-shedding irregular

-sometimes release from segments in LI and sometimes after excreted from horse

transmission of a perfoliata

orbatid mites

orbatid mites

-live on ground eating plant debris and lichens

-overwinter in soil

life cycle of a. perfoliata

The eggs released are infective to ORIBATID MITES, (IH).

Mites live on the ground eating plant debris and lichens - overwinter in the soil

Horses infected in Spring (grass) -ingest mites

eggs shed in horse faeces

seasonality of a perfoliata

-spring on grass as ingest mites

-disease actually affects october/november

PPP if a perfoliata

6-10 weeks

-shed large numbers of eggs

diagnosis of a perfoliata

-serological test

-ELISA for populations not individuals

-blood test (abody)

-saliva test (abody)

what is the immune response to a. perfoliata in older horses like

Immune response - worms within the intestine – more pronounced in older horses -more likely to clear the infection

treatment of a perfoliata

-high dose pyrantel (double dose needed for tapeworm)

-praziquantel in autumn/winter (tapeworm)

prevention of a perfoliata

stable horses for 48 hours after worming to prevent increased pasture contam

-cannot kill mites

most important large strongyle

strongylus vulgaris

what parts of the git do large strongyles affect

large intestine: colon and caecum

what does strongylus vulgaris cause

verminous arteritis → immune response in walls of bv

-dissemination through mesenteric arteries

-surgical colic

how has prevalence of strongylus vulgaris decreased

ivermectin

epidemiology of strongylus vulgaris

-some immunity but never complete to stop re infection

-disease often most severe in young/unexposed animals

-all ages but worse in weanlings and yearlings

-reservoirs- asymtomatic horses

why is diagnosis of strongylus vulgaris difficult

-difficult as pre patent disease

-disease caused by larval stage

diagnosis of strongylus vulgaris

-thrombi when rectal

-FEC not always useful as look like other strongyles

-more eggs does not mean lots of worms

seasonality of s vulgaris

high numbers on pasture in spring/summer so often in arteries in autumn/winter

signs of s vulgaris in adults

-protein losing enteropathy

-anaemia

-colic

-diarrhoea

-anorexia

-ischaemic necrotic gut

what can thrombi at aorto iliac junction in s vulgaris present as

lameness and poor performance

other organ effects of s vulgaris

migrate to brain, kidneys, lung, liver and form granulomas

treatment of s vulgaris larvae and adults

-benzimidazole and avermectin

treatment of just s vulagris adults

pyrantel

prevention of s vulgaris

-avoid overgrazing (eggs often on ground)

-pick up faeces regularly

s edentatus PPP and predeliction site

-hepatoperitoneal strongyle

-11 months

-can enter bv?

s equinus predeliction site and PPP

-hepatopancreatic strongyle

-do not enter blood vessels like other two strongyles

-9 months

s edentatus clinical signs

-colic as liver disease or peritonitis

s equinus clinical signs

-mild colic

-some assoc with pancreatic disease and primary diabetes mellitus

• both very rare

diagnosis for s. edentatus and s. equinus

• same as s. vulgaris

  • look for strongyle eggs in faeces

what is the most important equine parasitic disease in terms of prevalence and severity of clinical signs seen, resistance

Cyathostominosis

cyathostominosis (red worm)

clinical signs of cyathostominosis

-chronic diarrhoea

-colic

what kind of conditions does cyathostominosis like

high stoking densities

mild wet winters

why are cyathostominosis so hard to treat

-encysted hypobiotic larvae (L3) in LI unaffected by anthelmintic

-need to prevent getting to hypobiotic stage

-most of the infection are larval

PPP of cyathostominoasis

6-14 weeks

seasonality of cyathostominosis

-most larvae on pasture in autumn

-larvae mass emerge in spring→ damage

immunity of cyathostominosis

Do see immunity to cyathostominosis, but takes a long time and never complete

Younger horses more likely to have higher burdens

diagnosis of cyathostominosis

-difficult as PPP

-history and clinical signs of younger animal with poor worming history or change

-larvae in faeces or on glove after rectal

-elisa?

elisa for cyathostominosis

ELISA for cyathostomin larvae

• current ELISA for IgG antibodies against specific cyathastomin antigens

• looks at probabilities of total worm burdens but not at likelihood of clinical disease Horse Trust Small redworm ELISA guidlines

acute larval cyathostominosis

-spring time

-L3 larvae emerge→ due to mucosal damage then get colic, weight loss, D++, wasting and death

-SIRS and albumin loss leading to oedema

-sometimes hamorrhagic D++

autumn syndrome of cyathostominosis

-when larvae entering intestinal wall

-colic

-d+ due to inflam

oxyuris equi affects what age

any

oxyuris equi lives where

-parasite of stabled horse

-eggs don't survive outside

-reservoirs: other infected horses and environment

o.equi clin signs

-anal pruritis

-skin excoriation

-myiasis

diagnosis of o.equi

-eggs in perianal region on exam

-sellotape test by putting on slide and examining under microscope

o.equi treatment

-all anthelmintics should be effective but some resistance

-anal application as paste

-topical or systemic anti inflams to decrease pruritis and keep area clean with disposable material

prevention of o equi

good stable hygiene

-water troughs, mangers etc