Nematodes of Horses and Pigs

What are the important nematodes in the subfamily Cyathostomes for equine?

Small strongyles

What is the most common and main parasitic pathogen of horses?

Small strongyles

Where are adult small strongyles located in the horse?

In the colon and cecum

What is the prevalence of small strongyles?

Assumed to be 100%

What is the PPP of small strongyles?

6-18 weeks

What is the life cycle of small strongyles?

Egg to L3 in environment.

L3 is ingested and penetrates mucosa and can arrest here.

L3 molts to L4 within cysts

L4 emerge to lumen where they mature to adults and mate

What is the role of seasonality in small strongyle epidemiology?

In cool climates they can undergo hypobiosis in winter and lead to a "spring rise".

In warm climates there is transmission in all seasons except summer. Minimal arrested development.

What part of the small strongyle life cycle is responsible for most of it's pathology?

The larvae, once they emerge from cysts it can causes eosinophilic/lymphocytic infiltrates. Can cause ulcers where they emerged.

What is the pathology of adult small strongyles?

Minimal, superficial mucosal feeders, no observable feeders

What are the clinical signs of small strongyles?

Usually subclinical (even with high intensity infections)

Non-specific: poor growth, poor performance, weight loss, rough hair coat +/- diarrhea

There are _______ levels of acquired immunity for small strongyles in adult horses... what does this mean for FEC?

Variable levels

High immunity: low FEC

Poor immunity: High egg shedders

How to DX small strongyles?

NO specific test

Can do mcmaster FEC

What is larval cyathostominosis?

Disease caused by the massive, synchronous emergence of small strongyle larvae.

What does larval cyathostominosis cause?

Mucosal damage, mucosal edema, protein losing enteropathy

What are the clinical signs of larval cyathostominosis?

Chronic diarrhea, weight loss, ventral edema, rough hair coat, +/- colic/pyrexia.... death o-o

How to dx larval cyathostominosis?

No DX tests

Observation of large numbers of larval worms on palpation sleeve/feces + CS

FEC would be very LOW

What are strongylus spp common name?

Large strongyles

What is the prevelance of large strongyles?

uncommon in managed horses

What is the species name of "bloodworm"?

Strongylus vulgaris

What is the site of migration for strongylus vulgaris?

Cranial mesenteric artery

What does a strongylus vulgaris infection cause?

Thickening/fibrosis of arterial wall

Alterations of intestinal motility

Thromboembolism

Infarction

Why are large strongyles not common or important anymore?

They did not develop resistance to the drugs that small strongyles did

What is the horse ascarid?

Parascaris equorum

What is the most important parasite of foals and thus the primary target of parasite control programs?

Parascaris equorum

What is the largest nematode found in the horse's small intestine?

Parascaris equorum

What type of life cycle does Parascaris equorum have?

Direct

What is the life cycle of Parascaris equorum?

Ingest infective eggs (L2), larvae migrate liver, lungs, small intestine (same as Ascaris suum)

What is the PPP of Parascaris equorum?

10 weeks

What allows for parascaris equorum to be resistant to environmental degradation?

Sticky outer coat and proliferous repro

How is parascaris equorum dx?

Clinical signs

Detection of eggs in feces

Describe the pathogenesis of the larval migration to the liver of parascaris equorum?

Causes a scarred and hemorrhagic tract. "Milk spot" lesions on the liver. No CS/importance

Describe the pathogenesis of the larval migration to the lungs of parascaris equorum

CS with heavy infections

Pneumonia/Dyspnea

"Verminous pneumonitis"

Nasal D/C in foals

What life stage is of primary concern for parascaris equorum?

Adults

What are the CS of an adult parascaris equorum infection?

Rough hair coat

Impaired growth

Pot belly

LARGE # in SMALL INTESTINE -> gut motility impairment

What is the horse pinworm?

Oxyuris equi

Where do the adult oxyuris equi live?

In the distal large intestines of horses?

Where do female oxyuris equi lay eggs?

They extrude from the anus and lay eggs on the perineal skin

yikes

What type of life cycle does oxyuris equi have?

Direct

How are equines infected with oxyuris equi?

Ingestion of infective eggs (L3)

(Require time in environment to develop)

What are the CS of oxyuris equi?

All age groups affected

No GI signs

Intense perianal pruritus

How to DX of oxyuris equi

Eggs NOT seen on fecals usually

Sticky eggs on peri-anal area.... scotch tape test/scraping

How to TX/Control oxyuris equi?

Sanitation

Drug resistance is common

In order of economic importance, what are the swine GI and muscle nematodes we need to know?

Ascaris suum

Oesophagostomum spp

Trichuris suis

Trichinella spiralis

What is the pig ascarid?

Ascaris suum

What is the most common and most important helminth in swine?

Ascaris suum

The eggs of ascaris suum are very resistant in the environment, how long can they persist for?

>5 years

What type of life cycle does ascaris suum have?

Direct

What is the life cycle of ascaris suum?

Ingestion of larvated eggs (L3) (paratenic can occur)

Hepatotracheal migration (cough and swallow)

What are the CS of ascaris suum larval migration to the liver?

Scarring/milk spot lesions

Can lead to liver discard ($ loss)

What are the CS of ascaris suum larval migration to the lungs?

Verminous pneumonia

Resp dstress

Soft and moist cough

What is the pathology of adult ascaris suum?

Interfere with digestion and absorption (poor feed conversion)

Obstruction/rupture of intestines/bile ducts

How to DX ascaris suum

CS: Pneumonia, pot belly, ill thrift, diarrhea

FEC/Floats

What is the PPP of ascaris suum?

2 months

What is the control methods for ascaris suum?

Anthelmintic tx and improved sanitation

What is the nodular worm?

Oesophagostomum denatum

Where is the host specific nodular worm located in the host?

Oesophagostomum denatum is located in the large intestine

What is the pathology caused by oesophagostomum denatum?

Nodules in the large intestine mucosa caused by the larva.

What are the CS of oesophagostomum denatum infection?

Poor productivity, reduced growth, weight loss, poor litter

Where is trichuris suis located in the host?

Large intestine (cecum, colon)

What type of life cycle does trichuris suis have?

Direct

What is the infective stage of trichuris suis?

Eggs containing L1

What is the PPP of trichuris suis?

2-3 months

What are the clinical signs of trichuris suis infection?

Most are asymptomatic

High intensity can cause:

Mucosal hemorrhage

Enteritis/typhlitis/colitis

Diarrhea

How to DX trichuris suis

Fecal float

Necropsy

What is the major zoonotic parasite in pigs?

Trichinella spiralis

What is trichinella spiralis associated with?

Consumption of raw/undercooked pork/wild boar

How to DX trichinella spiralis

Detection of larvae in the muscle

What is REQUIRED for trichinella spiralis infection?

Carnivorism, no environment stage

What are the methods of control/prevention of trichinella spiralis?

Cook your meat

Freeze your meat