Parasitology - Lecture 22 & 23 (Horse large Inestine Parasites of the cecu, large colon, and small colon) Flashcards
Discuss The strongyles, like the basics
- Large strongyles
- Small strongyles (cyathiostomes)
- Very important –> bloodworms; below are considered LARGE strongyles
- Strongylus vulgaris –> L4 in cranial mesenteric artery
- Strongylus edentatus –> L4 in liver, flank
- Strongylus equinus –> L4 in liver, pancreas
Adult large strongyles –> anterior end has large buccal cavity
Life cycle:
Adult in Large intestine –> egg laid on pasture –> hatches –> L1, L2, L3* –> ingested by horse* –> penetrate wall of LI and molt to L4 –> penetrate arterioles –> large arteries –> Cranial mesenteric artery for 4 months –> arteries and arterioles –> LI, adult
Long life cyles –> PPP is 200 - 350 days
Discuss the oathology of Strongylus Vulgaris
L4 arterial migration endothelial damage predisposes to: anuerisms; thromboembolisms; rupture of vessels
- Other vessels (femoral artery –> lamness)
- Chronic infection –> mineralization in arteries; –> permanent damage
- Intestinal dmage:
- L4 migration through wall of LI –> hemorrhage
- **Adults feed on blood ** –> anemia, ill-thrift
- strongylaris vulagris is associated with cranial mesenteric artery migration
Discuss the diagnosis of Syrongylaris Vulgaris
Diagnosis:
- fecal float –> cannot differentiate by eggs - strongyglke eggs
- fecal culture –> 1) invubate feces at room temperature for 1-2 weeks 2) Pefrom baermann isolation of L3 srongyles and evaluate morphology
Necropsy:
- enlarged minerlaized CMA –> Pathognomic for S. Vulgaris
- Discuss prevention and treatment in regards to strongyles
- No treatment regimenb will overcome poor managemnt
- Pasture managemnt: stocking rates (horse/acre; pasture cleaning; rotational grazing
Prevention: Clean manure from pasture
Pasture L3 are very envoiornmentally stable
Treatment:
-adults: Benzimadoles –> fenbendazole
Macroccylic lactones
Pyrantel
Migrating Larvae –> ivermectin, mixodectin
Control: goal should involude aviud anthelmintic resiatcne
What is the quantitative fecal float
Quantitative fecal float –> McMasters
- quantifies the nbuynber of eggs poer gram of feces
- Best for determining the level of infectionof **strongygle eggs in horse or ruminant feces
- Fxns to estimate pasture contamination rates
Deworm whenb shedding is high
Discuss small strongyles
Cyathostomes –> includes 3 different species
Life cycle:
Adult in Large intestine –> strongyle egg –> L1, L2., L3 on pasture –> ingested bbybhorse –> encyst in cecum and large intestina mucosa as L3, L4 –> emerge into lumen –> adult
PPP = 40 days
Discuss the pathology of small strongyles and also discuss diagnososis
- Most dmaage is caused by larval stages
- Chronic mild granulomatous typhlitis and colitis
- Larval cyathostomaiasis –> mass ermergence of larval small strrongyles
Diagnosis: Antemortem:
- Fecal float –> encysted larvae do not produce eggs so this means we cannot detect clinical larval cyathostomiasis
- Fecal culture –> smalll strongygle L3 has <10 intestinal cellls
- Culture fecal samples:
- do a Baermann to isolate 3rd stage infective larvae (L3s)
- Large strongyles have >16 intestinal cells (S. vulagris has 32 cells)
- small strongyles have < 10 intestinal cells
- do a Baermann to isolate 3rd stage infective larvae (L3s)
Discuss treatment of small strongykles
- Encysted larval stages are difficukt to treat
- **unaffected ** by routine pyrantel, fenbendazole, and ioral ivermectin
- *Moxidectin ** is efficacious against some encysted larva
Widespread anthelmintic resitance in small stringyles
- ANthemintics involved: Fenbendazole
No resistance reproted to ivermectin/moxidectin
Discuss anthelmintic resistance and factors that drive it
ANthelminitic resistance is driven by these factors:
- Increased number of treatments
- Undeerdosing
- Owner
Reduction of selection pressure (in relatuion to anthelmintic resiatnce) via:
- Pasture mangement toi control infection levels –> most importantly, stocking rates (horse/acre) is the most importatant management factor
- minimize numnber of treatments
- INfivifdualized treatments based on fecal egg counts
- Still treat all horses in falll to kill S. vulgaros L4s
When considering horse large intestinal parasites, which ones fall under this category. also discuss the basics
- Oxyuris equi –> pinworm
Life cycle: female adult –> repeatedly migrates out of rectum –> eggs around anus –> irritation —> horse rubs -_> eggs contaminate enivornment –> egg os eaten –> adult inn Large intestine (small colon)
PPP - 5 monthsa
Clinical signs: puriritis, irritation, rubbing –> damage to tail and hair
Discuss the diagnosis of oxyuris equi
Diagnosis:
- scotch taope method is much more reliable than the fecal float
Prevention/control –> pyrantel, piperazine, ivermectin
Now, discuss Dictyocaulus arnfieldi
Dictyocaulus arnfieldi –> lungworm
- primarily a lungworm of dinkeys
- nonpathogenic in donkeys; but can cause severe dusease in horses
- lives in large airways
Direct life cycle in donkeys: adults in lungs lay eggs –> egg coughed up and swallowed –> hatches in intestines –> L1 in feces –> L3 on pasture –> ingested –> L3 eneters circulation –> lungs
- Can infects horses but **no patent infection dvelops
Now, discuss Setaria spp
Setaraia spp –> filarial worm transmitted by mosquitoes
- anincindental finding
Discuss Thelazia spp
Thelazia spp –> eye worms
Transmitted by face flies
Usually nonpathogenic but can cause conjunctivitis
Treatment: manuall removal an/dor oral ivermectin
Prevention: fly control
Discuss Halicephaloigobus gingivalius
- Environmental soil nematode, opportunistic ingection
- locates in nasal sinys, but can migrate into the brain
- Clinical signs: lack of condition; nonspecific neurologic signs
Discuss Horse Cestodes
- Anoplocephala perfoliata –> ileocecal junction
Life cycle: eggs in feces –> ground –> cysticercoid in pasture mite –> ingested by horse –> tapeworm in small intestine or at ileocecal jucntion
