C23 Gastrointestinal Pathology VI Flashcards
- All parasites are more common than the diseases they cause
o Helminthiasis = ?
o Helminthosis = ?
- All parasites are more common than the diseases they cause
o Helminthiasis = infection with parasites
o Helminthosis = disease caused by parasitic infection
Helminths: general considerations
* 5 categories of pathologic effect:
- strategy
- pathogenicity
- possible sequelae
- examples
- Live free in lumen, compete for nutrients
- pathogenicity: Low unless very high burdens
- possible sequelae: Physical obstruction
- eg. Cestodes, some adult nematodes (ascarids)
<><><><> - Blood loss via direct consumption or mucosal damage
- pathogenicity: Moderate-high
- possible sequelae: Anemia
- eg. Nematodes
<><><><> - Protein-losing gastroenteropathy due to inflammation
- pathogenicity: Moderate
- possible sequelae: Wasting, anorexia
- eg. Nematodes, some trematodes
<><><><> - Physical trauma to gut wall due to adult feeding or larval emergence
- pathogenicity: Moderate-high
- possible sequelae: Perforation, adhesions
eg. Nematodes and trematodes
<><><><> - Damage to sites distant from gut, usually migrating larvae
- pathogenicity: Moderate-high
- possible sequelae: Depends on tissue
- eg. Mostly nematodes, some cestodes
Diagnosing helminthosis requires three criteria:
1) Helminth is present in sufficient numbers to cause disease
2) Lesions typical of the helminth are present
3) The clinical syndrome is compatible with the pathology caused by the helminth
Nematodes
* Nematodes of herbivores tend to have similar direct life cycles…
GIN eggs on pasture, from poop
> infective larvae in grass
> ingested
> winter: hypobiosis
> adult GINs
> ~21 dats
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Mixed infections are typical
Nematodes
* Ostertagiosis
- agent in cattle and sheep?
- geography
- signs
- pathogenesis, lesions
- Ostertagiosis: Ostertagia ostertagi in cattle, Teladorsagia circumcincta in sheep
o Important abomasal parasite in temperate regions
o Subclinical production losses, clinical diarrhea, wasting, death
<><><><> - Infective larvae invade gastric glands
- Cause inflammation, mucous metaplasia, and glandular hyperplasia before emerging
- Adults live in lumen (too small to see easily)
<><> - Thickened mucosa at sites of larval penetration In heavy infection, ‘Morocco leather’
Nematodes
* Ostertagiosis
- type I and II disease
> age groups, what happens
> signs
- Dx
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- when can we see type II and I
- diarrhea?
- PM lesions
o Type I disease: young animals under high challenge
o Lots of worms develop at once, causing chronic gastritis
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o Type II disease: yearlings, due to synchronous emergence of hypobiotic larvae o Acute gastritis that can be fatal
<><>
- damaged gland > Reduced acid, Leakage of pepsinogen into bloodstream > Diarrhea (cows only), Loss of appetite, wasting
<><>
Confirm via abomasal pH, worm count (must digest to see larvae), plasma pepsinogen
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o Periparturient rise in females when hypobiotic larvae resume development (type II)
o Disease in adults and young animals on contaminated pasture (type I)
o NO DIARRHEA
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- carcass pallor
- Hydropericardium +/- ascites, hydrothorax
Nematodes
* Haemonchosis
- species, agents
- geography
- feeding
- environmental survival
- signs in acute and chronic cases? burdens?
- Haemonchosis: H. contortus in small ruminants, H. placei in cattle
- can also affect llamas
o Major abomasal pathogen in tropical areas and climates with warm summers
o Adults and late-stage larvae are voracious blood feeders (~0.05 mL/worm/day)
o Able to survive environmental extremes via hypobiosis
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Aka barberpole worm Large adults (~2 cm)
<><><><>
Acute/peracute: heavy burdens - Severe anemia and hypoproteinemia
- May die suddenly and before patency
- Weak, exercise intolerant
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Chronic: lower burdens - Bottle jaw (edema) due to hypoproteinemia more common than in acute cases
- Death due to iron deficiency
Nematodes
* Trichostrongylus spp.
- mostly what agent
- species?
- anatomic location? signs?
- pathogenesis
- clinical signs due to…
- signs? why?
- Dx
sheep, cattle
<><><><>
* Trichostrongylus spp.: mostly T. colubriformis
o Infects SI, causing production loss, ill thrift, diarrhea, death
o Larvae tunnel in epithelium and adults remain partly embedded
o Causes villus atrophy and hyperplastic crypts
o Clinical signs due to loss of plasma into gut, gross lesions are nonspecific
o May see edema and effusions in non-dehydrated animals due to hypoproteinemia
<><>
typical GIN eggs in feces
Nematodes
* Trichostrongylus axei
- species?
- anatomic location
- mechanism?
- lesions
- signs?
- Ddx?
<><>
- in the horse?
- lesions?
- sheep, cattle
- Trichostrongylus axei
o Abomasal/gastric nematode, often mixed infection but high solo burdens pathogenic o Similar mechanism of pathology to T. colubriformis
o Mucous metaplasia/hyperplasia forms raised white plaques or nodules
o May cause achlorhydria in heavy infection, causing diarrhea (especially in cattle)
o Plasma pepsinogen increases, causing inappetence and wasting
o Main differential is ostertagiosis, but intraepithelial location is distinctive
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Horse:
o Uncommon, usually in horses grazed with ruminants
o Stomach lesions are commonly seen in chronic infections
Nematodes
* Strongyloides spp.
- who is affected?
- forms?
- parasitic forms are always ___
- free living issues?
- go through what tissues?
- cause what issue with heavy burdens? how?
<><>
horse
pig
cat
dog
cattle
sheep
- what strongyloides spp., and what do they cause in each?
<><>
-eggs?
o Different species affect all domestic mammals, free-living and parasitic forms
o The parasitic forms are all female (parthenogenesis)
o Free-living forms undertake sexual reproduction and larvae penetrate skin
o Migrate through lungs before reaching gut via mucociliary escalator
o Tunnel in epithelium at junction of villus and crypt, causing crypt atrophy and inflammation in heavy burdens
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Horse: S. westeri
- Diarrhea
- Fatal in high burdens
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Pig: S. ransomi
- Diarrhea
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Cat: S. felis
- Pneumonia (migration)
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Dog: S. stercoralis
- Commonly fatal in puppies up to 2-3 months old
- Blood-tinged diarrhea, dehydration, emaciation
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Sheep and cattle: S. papillosus
- Diarrhea
- Sometimes death
<><><><>
Larvated eggs (unlike other nematodes)
Nematodes
* Nematodirus spp.
- species
- amatomic location?
- temperature
- pathogenesis
- disease course
- lesions
- sheep, cattle
o Infects proximal SI, often needs cold exposure for eggs to hatch
o Larvae mature in deep mucosa, then emerge to coil around villi -> malabsorption
o Annual disease in youngstock: severe dark green diarrhea, anorexia, wasting, death
o Nonspecific gross lesions (‘cotton wool’ appearance of adults)
Nematodes
* Oesophagostomum spp.
- species
- pathogenesis?
- lesions
- possible outcomes
- possible signs
- cattle vs pig dz
- sheep, (cattle, pigs)
o Larvae encyst deep in mucosa, producing
inflammatory nodules
o Resembles pimples up to 1 cm projecting
from serosa with caseous contents
o Usually incidental but can cause
adhesions or peritonitis
o Adults in colon lumen cause anorexia,
diarrhea, ill thrift
o In cattle, larvae cause protein loss
o Mild and subclinical in pigs
Nematodes
* Cooperia spp.
- species
- location
- winter
- pathogenesis, signs
o Most important in cattle, infects upper SI, capable of hypobiosis
o Coils around villi like Nematodirus spp. -> inappetence, poor growth, diarrhea
<><>
- can also affect sheep
Nematodes
* Chabertia ovina
- appearance
- pathogenesis
- signs
- species
o 1-2 cm long, thick nematode of colon, feeds on plugs of mucosa
o Hemorrhage and protein loss due to physical trauma
o Nonspecific clinical signs (ill thrift, diarrhea +/- blood)
- sheep, cattle
Nematodes
* Strongyles in the horse
- common in what anatomic locations?
- two subfamilies, what they feed on, notes
- Strongyles are common in the cecum and colon and fall into two subfamilies:
o Strongylinae (large strongyles): mostly Strongylus spp., blood or plug feeders with
extensive extraintestinal migratory phase
o Cyathostominae (small strongyles): 8 genera, adults feed on gut contents so cause
limited pathology but synchronous larval emergence can be damaging
