Common Equine Parasites Overview
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Questions and Answers

What is the prepatent period for small strongyles compared to large strongyles?

  • Same duration as large strongyles, usually several months
  • Consistently longer than large strongyles due to migration
  • Typically shorter than large strongyles, as short as 40 days (correct)
  • Longer due to a dormant stage that can last years

Which of the following is a characteristic of the life cycle of small strongyles?

  • Their larvae are directly ingested without any previous stages
  • They undergo hypobiosis in response to environmental temperatures (correct)
  • They have a complex life cycle with multiple host species
  • Transmission occurs via insect vectors

Which of the following is an effective treatment for encysted small strongyles?

  • Ivermectin
  • Pyrantel pamoate
  • Praziquantel
  • Fenbendazole (correct)

What clinical signs are specifically associated with S. vulgaris larvae damage?

<p>Aneurysm and arteritis (D)</p> Signup and view all the answers

Which of the following methods is NOT effective in diagnosing strongyles?

<p>Serological tests for species differentiation (B)</p> Signup and view all the answers

What is the primary goal of evidence-based deworming in horses?

<p>To avoid increased drug resistance (D)</p> Signup and view all the answers

Which class of anthelmintics includes Ivermectin and Moxidectin?

<p>Macrocyclic lactones (A)</p> Signup and view all the answers

How often should fecal egg counts (FEC) be monitored for deworming success?

<p>Regularly for all horses on the property (B)</p> Signup and view all the answers

What is a significant fecal egg count (FEC) that indicates the need for deworming?

<p>100 EPG (C)</p> Signup and view all the answers

What should be avoided to minimize the risk of resistance to anthelmintics?

<p>Frequent treatment of all horses (A)</p> Signup and view all the answers

Which anthelmintic is effective against both large strongyles and cyathostomes?

<p>Moxidectin (B)</p> Signup and view all the answers

What type of parasites are preserved in parasite refugia?

<p>Wild-type parasites and untreated horses (B)</p> Signup and view all the answers

What is the recommended approach for treating horses responsible for significant environmental contamination?

<p>Only treat those with high FEC (A)</p> Signup and view all the answers

What is the pre-patent period for Strongylus vulgaris?

<p>6 months (B)</p> Signup and view all the answers

Which of the following species is a type of large strongyle?

<p>Strongylus edentatus (A)</p> Signup and view all the answers

What are the characteristics of small strongyles?

<p>They are known as cyathostomes and include at least 52 species. (D)</p> Signup and view all the answers

How long can L3 strongyle larvae overwinter on pasture?

<p>Most of the winter (C)</p> Signup and view all the answers

What type of life cycle do strongyles have?

<p>Direct life cycle (A)</p> Signup and view all the answers

What is the common term for large and small strongyles?

<p>Bloodworms (B)</p> Signup and view all the answers

Which of the following is NOT a species of large strongyle?

<p>Parascaris equorum (A)</p> Signup and view all the answers

What is the primary method of transmission for Strongylus vulgaris?

<p>Fecal-oral transmission (A)</p> Signup and view all the answers

Which category of equine parasites ranks highest in importance?

<p>Strongyles (B)</p> Signup and view all the answers

What is the typical size range of large strongyles?

<p>2 to 5 cm long (D)</p> Signup and view all the answers

Which strongyle is known to be the primary cause of colic due to its damaging effects on blood supply?

<p>Strongylus vulgaris (B)</p> Signup and view all the answers

What anatomical location does the L4 stage of Strongylus vulgaris primarily migrate to?

<p>Cranial mesenteric artery (C)</p> Signup and view all the answers

How long does the L4 stage of Strongylus vulgaris mature to L5 in the mesenteric artery?

<p>3 to 4 months (B)</p> Signup and view all the answers

Which of the following conditions can occur due to the migration of Strongylus vulgaris?

<p>Arteritis (B)</p> Signup and view all the answers

What is the prepatent period for Strongylus equinus?

<p>9 months (B)</p> Signup and view all the answers

Which strongyle species migrates to the liver and peritoneum rather than the cranial mesenteric artery?

<p>Both B and C (C)</p> Signup and view all the answers

What factors contribute to the reduced incidence of strongyle infestations in well-managed herds?

<p>Effective deworming programs (B)</p> Signup and view all the answers

What is the primary role of L5 in the life cycle of Strongylus vulgaris?

<p>Emergence in large intestine (A)</p> Signup and view all the answers

Which of the following best describes the L3 larval stage of Strongylus spp.?

<p>It is resistant to cold and desiccation. (B)</p> Signup and view all the answers

Flashcards

Evidence-Based Horse Deworming

A three-pronged approach to deworming horses that prioritizes treating only those needing it, targeting specific transmission seasons, and safeguarding parasite refugia.

FEC

Fecal Egg Count (Quantitative fecal analysis to measure worm eggs/gram in horse feces)

Anthelmintic Resistance

The ability of parasites to withstand the effects of deworming medications.

Parasite Refugia

Untreated parasite populations that haven't been exposed to deworming medications.

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Macrocyclic lactones

A class of deworming drugs that includes Ivermectin and Moxidectin.

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Benzimidazoles

A class of deworming drugs that includes Fenbendazole and Oxibendazole.

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Cyathostomes

A group of large intestinal strongyles causing serious equine health issues.

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EPG

Eggs per gram, a measurement of the number of parasite eggs found in a gram of horse feces.

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Strongyle L3

The third larval stage of strongyles, which penetrates the small intestine mucosa after ingestion and molts into the L4 stage.

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Strongyle L4

The fourth larval stage of strongyles, migrating upstream to the cranial mesenteric artery where it matures to L5.

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Strongyle L5

The fifth larval stage of strongyles, encapsulating in the cecum or colon for final molt before emerging as adults.

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Cranial Mesenteric Artery

The primary blood supply for the cecum and colon, often targeted by strongyle L4.

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What are the potential complications of strongyle L4 migration?

Migration can cause aneurysm, arteritis, thrombus, embolus, infarction and verminous colic due to compromised blood supply to the GI tract.

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S.vulgaris Prepatent Period

The time between a strongyle egg being ingested and the first eggs appearing in the horse's feces, typically about 6 months for S.vulgaris.

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S.edentatus Prepatent Period

The time between a strongyle egg being ingested and the first eggs appearing in the horse's feces, typically about 11 months for S.edentatus.

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S.equinus Prepatent Period

The time between a strongyle egg being ingested and the first eggs appearing in the horse's feces, typically about 9 months for S.equinus.

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S.edentatus and S.equinus Larval Migration

Larvae of S.edentatus and S.equinus migrate to the peritoneum and liver, unlike S.vulgaris which targets the cranial mesenteric artery.

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S.edentatus and S.equinus Adults

Adult S.edentatus and S.equinus are larger and require more blood than S.vulgaris.

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Large Strongyle Feeding

Large strongyles, like Strongylus vulgaris, are 'plug feeders' that tear off pieces of intestinal lining, digest them, and move to a new feeding site. They don't suck blood, but the tissue damage can lead to significant blood loss.

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Larval Cyathostomes

Small strongyles, also known as cyathostomes, can cause a serious condition called 'larval cyathostomiasis'. They encyst in the gut wall and remain dormant in a stage called hypobiosis until they emerge en masse, causing inflammation and severe diarrhea.

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Hypobiosis

Hypobiosis is a state of dormancy that some cyathostome larvae enter. In this stage, they can survive for months in the horse's gut and are resistant to many deworming medications.

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S. vulgaris Larval Migration

The larva of Strongylus vulgaris migrates to the cranial mesenteric artery, a major blood supply to the gut. This can cause serious problems like aneurysms, inflammation, and even blood clots.

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What are Strongyles?

Strongyles are a type of parasitic roundworm that commonly infects horses. They are also known as 'bloodworms' or 'redworms' because they live in the large intestine and feed on blood and tissue.

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What is the life cycle of Strongylus vulgaris?

The Strongylus vulgaris life cycle is direct and fecal-oral. Horses ingest the infective L3 larvae, they migrate to the artery, mature to L5, then move to the large intestine to become adults. The cycle repeats when eggs pass in feces.

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What is the prepatent period of Strongylus vulgaris?

The prepatent period for Strongylus vulgaris is approximately 6 months, meaning it takes this long from a horse ingesting an egg for the first new eggs to appear in their feces.

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What is the difference between Large and Small Strongyles?

Large strongyles (Strongylus vulgaris, equinus, and edentatus) are larger and migrate through the blood vessels, while small strongyles (cyathostomes) mainly live in the intestinal wall and don't usually migrate.

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What is the main difference between Strongylus vulgaris and Strongylus edentatus/equinus larval migration?

Strongylus vulgaris larvae migrate to the cranial mesenteric artery, while Strongylus edentatus and Strongylus equinus larvae migrate to the liver and peritoneum.

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What is the consequence of Strongylus vulgaris larval migration?

Larval migration through the cranial mesenteric artery can lead to serious health issues like aneurysms, arteritis, and colic due to compromised blood flow.

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What is the infectious stage of Strongylus vulgaris?

The L3 stage is the infectious stage of Strongylus vulgaris, which is found on pasture and can overwinter in most U.S. climates.

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Where do Strongyles live in the horse?

Strongyles live in the large intestine of the horse, specifically in the cecum and colon.

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What is the main difference between Large and Small Strongyles' life cycles?

Large strongyles migrate in the bloodstream, while Small strongyles primarily live in the intestinal wall. Large strongyles have longer prepatent periods.

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Why are Strongyles considered a serious threat to horses?

Strongyles can cause severe intestinal damage, anemia, colic, and can even be fatal due to their blood-feeding habits and migration through vital blood vessels.

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Study Notes

Common Equine Parasites

  • Strongyles are important equine parasites, categorized by descending order of importance
  • Strongyles include large strongyles and small strongyles
  • Large strongyles (e.g., Strongylus vulgaris) are 2-5 cm long
  • Small strongyles (e.g., cyathostomes) are <1.5 cm long
  • Strongyles have a direct life cycle, involving fecal-oral transmission
  • Pre-patent period for Strongylus vulgaris is 6 months
  • Large strongyles adults live in the cecum and colon
  • Adults ingest tissue and blood
  • Ova pass in manure and hatch
  • Molt to L3 stage in 1-2 weeks
  • Adult strongyles emerge from nodules and begin reproduction
  • Horses can experience both large and small strongyles

Strongyle Species

  • Strongylus vulgaris is a large strongyle, characterized by a direct life cycle and fecal-oral transmission. The pre-patent period for S. vulgaris is 6 months
  • Adults live in the cecum and colon.
  • Ova pass in horse manure and hatch
  • Larvae molt to L3 stage in 1–2 weeks
  • Strongylus edentatus and S. equinus are similar in life cycle to S. vulgaris, they migrate to the peritoneum (S. edentatus) and the liver (S. equinus)
  • At least 52 different small strongyle species are categorized as cyathostomes or cyathostomins, and are common in horses.

Small Strongyles

  • Small strongyles have a direct life cycle, fecal-oral transmission, and a prepatent period as short as 40 days, but sometimes months or even years due to hypobiosis (dormancy).
  • Adults reside in the cecum and colon
  • L3 larvae undergo mucosal migration in the cecum and colon wall and encyst; at this point they go into hypobiosis
  • They are highly resistant to anthelmintics while encysted
  • Fecal samples often show evidence of larvae, which can cause clinical signs, not necessarily adult strongyles.
  • "Cyathostomiasis" is a clinical sign of large numbers of L5 larvae migrating into the intestine.

Clinical Signs of Strongyles

  • Large strongyles can lead to anemia, anorexia, depression, weight loss, and dehydration
  • Damage is due to blood loss from mucosal damage and plugging of intestinal villi.
  • Small strongyles cause similar but milder clinical signs due to smaller size
  • Signs may also include diarrhea and weight loss, along with copious mucus production in the large intestine

Diagnosis

  • Fecal egg counts (FEC) are used to determine the presence and quantity of strongyle eggs.
  • Clinical presentation is also important along with egg count analysis.

Prevention and Treatment

  • Good pasture management practices to limit environmental contamination
  • Regular deworming schedules based on FECs, and using multiple classes of anthelmintics, can help reduce strongyle burdens
  • Resistance development to anthelmintics is a concern.

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Equine Strongyles PDF

Description

This quiz covers the important equine parasites, specifically focusing on strongyles. Discover the characteristics, lifecycle, and significance of both large and small strongyles, and understand their impact on horse health. Test your knowledge on this vital aspect of equine care.

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