Ch49.ParasiteControlPrograms Flashcards
Define egg reappearance periods
period of time from anthelmintic treatment until parasite eggs are found in the feces again
Define prepatent period (PPP)
time elapsed from teh uptake of the infective stage of the parasite until it reaches patency and starts hseeding eggs to be detected in feces
What is the PPP of equine parasites?
Cyathostomins: 2-3 months
Parascaris equorum: 2-3 months
Anaplasma perfoliata: 1.5 to 4 months
Strongylus vulgaris: 6-7months
Strongylus edentatus: 11-12 months
What is the 20/80 rule in regards to parasite shedding?
20% of the host animals harbor approximately 80% of the parasites
** ie: about 20% of the hroses are shedding 80% of the total strongyle egg output
define parasite refugia
parasite stages that escaped antihelmintic drugs and are viewd as refugees
** important factoraffecting the rate of development of anthelmintic resistance in large animal parasites
Resistance to what anthelmintics is seen in Parascaris species?
ivermectin & moxidectin
Larvae from which parasite penetrate the mucosal lining of SI/stomach and migrate the classical hepatoctracheal route, passing through lungs causing airway symptoms in young foals?
Parascaris
Which parasite gives foals clinical signs of ill-thrif, weight loss, rough hair coat and pot-bellied appearance?
Parascaris spp
What is the major clinical impact seen with Parascaris infections?
verminous small intestinal impactions
**survival beyong 1 year after colic incident associated with parascaris reporte d in 11 of 37 cases
What is a significant risk factor for verminous small intestinal impactions associated with Parascaris in foals and why?
anthelmintic treatment d/t instant paralysis elicted by dewormers
** USe Benzamidazole t ype drugs
What are the major clinical consequences of Cyathostomins (small strongyles) infections?
excystment– L4 penetrate their cysts & migrate short distance back to the intestinal lumen
*acute typholocolitis– larval cyathostominosis
What is the case fatality rate reported with acute typholocolitis caused by small strongyle larval cyathostominosis?
50%
What is the anthlemintic drug of choice for treatment of encysted small strongyles?
moxidectin (400 microg/kg PO)
**also labeled is the 5 day dose Fenbendazole (10 mg/kg PO once daily)
Which parasites are associated with ileal impactions and ilecoceal intussceptions?
Tapeworms (A. perforliata)
What anthelminitics are labeled for treatment of tapeworms?
praziquantel & pyrantel pamoate
Which stage of large strongyles (Strongylins) migrate to the cranial mesenteric artery?
L4
IN the cranial mesenteric artery, what do large strongyles do?
Molt to L5– causing a pronounced verminous endarterities with roughened intima, fibrosis of arterial walls & INC diameter of vessels
What is the cause/pathogenesis of Strongylus vulgaris cranial mesenteric arterities?
Thrombi detach from the arteritis lesions (caused by L4 to L5 larvae) causing occlusion of terminal branches of vessels leading ot ischemia and infarction of intestinal segments–> colic
Foals are usually asymptomatic to Strongylus westeri parasites, how are they exposed?
lactogenic transmission from the mare, or through skin
What is the equine pin worm
O. equi
What causes the perineal pruritis assocaited with O. equi infections?
egg patches dry up that become pruritic
what parasite has been confused with the widely occurring culidcoides hypersensitivity?
Onchocerca spp– proundounced skinr eactions ventral midline and face
Halicephalobus gingiivals larvae have a special affinity for which organs?
CNS
Kidneys
**multifocal, esoinphilic lesions causing C/S blindness, ataxia, CP deficits, head pressing, comba, death, etc.
**infection extremely rare
