Equine gastrointestinal parasites Flashcards

Question

Which horses are usually affected by Parascaris suum? Why?

Answer 1

- usually causes dz in horses less than 2y/o -- immune response more developed in older animals

Answer 2

- 10-50% - quite common - but clinical dz is rare

Answer 3

- Parascaris equorum

Answer 4

- adult horses -- small numbers but shed enough eggs to infect foals/young stock

Answer 5

- Coughing and nasal discharge – often ‘mini- outbreaks’ on farms – when parasites in the lungs – some of this is hypersensivity to worm - Should be on ddx for young horses that are coughing - Poor coat and weight gain, dull, anorexic -- adults compete for nutrients in the intestinal lumen and for micronutrients so commonly presents with poor coat & weight gain - Occ colicking incl bowel obstruction -- can get complete SI obstruction due to the size of the parasite -- present with signs of acute colic, systemic inflammation, and this presentation can be fatal - Disorders of bone and tendons as the parasites consume lots of Ca, P, Zn, Cu - Diagnosis can be difficult – very distinct eggs when present

Answer 6

▪ MDR – Avermectins ▪ Only ascarid with MDR – none in pigs, dogs and people -- likely relates to the treatment regimes we have and use ▪ Drug rotation DOES NOT prevent resistance. Selects for MDR parasites. Stick to drugs that work ▪ Can see colic if treat lots of adult worms with paralytic drugs – (avermectins and pyrantel) ▪ PYRANTEL -- drug of choice

Answer 7

- usually young horses but can be any age

Answer 8

Colic ▪Ileal impaction – often very painful ▪ Intussusceptions ▪Caecal impactions and motility disorders ▪Spasmodic (gas) colic ▪ (Diarrhoea) ▪Functional and physical blockages

Answer 9

- irregular - sometimes released from segments in LI - sometimes released after excreted from horse

Answer 10

- Oribatid mites (intermittent host) - Mites live on the ground and overwinter in the soil - horses are infected in spring (grass) -> mite ingestion - only equine parasite that has an indirect life cycle

Answer 11

- 6-10w - can then shed large numbers of eggs

Answer 12

- in Oct/Nov

Answer 13

▪ Immune response - worms within the intestine – more pronounced in older horses -more likely to clear the infection -- Basis of a semi-quantitative serological test -- ELISA for diagnosis IN POPULATIONS – BUT NOT FOR INDIVIDUAL DIAGNOSIS -- LOTS of false positives * Blood test (approx £30) numerous labs run * Salivatest (Approx.£18) ▪ These are antibody tests – values are historic ▪ Currently <25% of horses tested require treatment Diagnosis based on antibody detection

Answer 14

▪Two drugs – high dose pyrantel (double dose required for other worms) and praziquantel – treat in Autumn/Winter ▪Prevention – stable horses for 48 hours after worming to prevent increased pasture contamination. Can’t kill the mites

Answer 15

- ascarid eggs are unique - round and lumpy - look like desiccated raison - reports that they can survive for up to 10y on pasture

Answer 16

- Strongylus vulgairs - causes verminous arteritis -- basically am immune response in the wall of the blood vessels - lifecycle involves dissemination through the mesenteric arteries - was very important cause of surgical colic that was frequently fatal -- mainly larvae that cause dz

Answer 17

- fallen since use of wormers containing ivermectin as worm very sensitive - 20y ago was ~60% - now ~6%

Answer 18

- get some immunity but never complete to stop re-infection

Answer 19

- young/unexposed animals

Answer 20

- seen in all ages - worse in weanlings and yearlings

Answer 21

- asymptomatic horses that shed large numbers of eggs

Answer 22

▪Difficult as this is a pre-patent disease – disease caused by larval stage ▪May be able to feel thrombi (in the mesenteric arteries) when perform rectal examination ▪Faecal analysis –not always useful and can’t tell from other Strongyle eggs ▪No correlations with Strongyle egg counts and luminal worm counts! ▪Thus increased egg counts DOES NOT mean large worm burdens ▪What we also don’t know is whether the worm burden (which we can’t easily measure) correlates with disease

Answer 23

▪ Adults – protein-losing enteropathy and anaemia ▪ Colic, diarrhoea, anorexia ▪ Ischaemic, dying gut=sick, colicking, dying horse – need surgery for resection if possible ▪ Can form thrombi at aorto-iliac junction – can lead to lameness and poor performance - as affects/reduces blood supply to major arteries of the hindlimbs ▪ Occasionally migrate aberrantly and end up in the brain, kidneys, lungs, liver and can form granulomas

Answer 24

- Autumn/winter - high numbers on pasture in spring/summer, often in arteries in autumn/winter, which is when dz is seen

Answer 25

▪Drugs -- benzimidazoles and avermectins – larvae and adults -- Pyrantel – adults only ▪All drug groups still OK for use but same as for small strongyles when it comes to identifying horses requiring tx ▪Avoid overgrazing (eggs often on ground) ▪Pick up faeces regularly

Answer 26

- hepatoperitoneal strongyle

Answer 27

- 11 months - long as goes through over and peritoneal cavity as part of lifecycle

Answer 28

- hepatopancreatic strongyle - they don't enter blood vessels like the other 2 strongyles -- therefore, less likely to cause infarction and mesenteric dz

Answer 29

- 9 months - goes through liver and pancreas as part of lifecycle

Answer 30

- colic due to liver dz or peritonitis

Answer 31

- mild colic - some associated with pancreatic dz and primary DM -- both of these conditions are extremely rare in horses

Answer 32

- Cyathostominosis

Answer 33

- severe acute d+ & colic - chronic d+

Answer 34

- no, they are largely unaffected by any anthelmintic

Answer 35

- in spring - often loads at once

Answer 36

- 6-14w if no hypobiosis

Answer 37

- in autumn

Answer 38

- do see it but takes a long time an never complete - younger horses more likely to have higher burdens

Answer 39

▪ Very difficult as PPP disease ▪ History and clinical signs – young animals, poor worming history or change ▪ May see larvae in faeces or on glove after rectal examination in animals with acute larval cyathostominosis ▪ The future - 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

Answer 40

▪First syndrome – seen in SPRING ▪ACUTE LARVAL CYATHOSTOMINOSIS ▪Due to mucosal damage caused by emergence of the late L3 - Colic - Weight loss - Diarrhoea – acute and chronic -- can be very profuse and watery -- sometimes slightly haemorrhagic - Wasting and death either acutely or chronically - Often affected by the loss of mucosal integrity -- often have bacteraemia, severe SIRS, protein loss (particularly albumin) across the gut so can get ventral and peripheral oedema due to loss of oncotic pressure

Answer 41

▪Autumn syndrome – when larvae entering intestinal wall – less common than that seen in the Spring ▪Colic ▪Diarrhoea due to inflammation

Answer 42

- affects any age - parasite of stabled horses (eggs don't survive well outdoors)

Answer 43

- other infected horses and immediate environment

Answer 44

▪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

Answer 45

▪All anthelmintics should be effective – some resistance ▪ Anal application as a paste -- way to target anthelmintic at the area of likely highest burden -- but most important thing is hygiene to manage these ▪Can use topical or systemic anti-inflammatories to decrease pruritus and keep area clean with disposable material ▪Good stable hygiene – water troughs, mangers etc

Answer 46

- high stocking densities - mild wet winters

Answer 47

- in the wall of the large colon and caecum

Equine gastrointestinal parasites Flashcards

(75 cards)