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What nematodes affect horses?
Parascaris equorum
Oxyuris equi
Dictyocaulus arnfieldi
Filarial nematodes
what cestodes affect horses?
Anoplocephala perfoliata
what ectoparsites affect horses?
lice
Chorioptes
Bots - Gastrophilus
Sweet itch - Culicoides spp
what trematodes affect horses?
Fasciola hepatica
what are the characteristics of tapeworms?
adult parasites primarily found in small intestine
indirect life cycle - involves oribatid mite as intermediate host
what are features of Anoplocephala perfoliata?
most common and most significant species
adult tapeworms found at ileo-caecal junction
short, broad segments
lappets behind each of four suckers
what is the life cycle of A. perfoliata?
eggs ingested by free-living oribatid mites
develop to metacestode stage
found in soil, shavings and hay
infected mite ingested by horse
adult tapeworm at ileo-caecal junction
proglottids passed in faeces, disintegrate and eggs released
what is the appearance of A. perfoliata eggs?
irregularly spherical (D shape)
60-80um
onchosphere supported by pyriform apparatus
what is the pathogenesis of A. perfoliata?
spasmodic colic
intussusception
ileal impaction
rupture
what are the clinical signs of A. perfoliata?
ulceration and pathological changes in intestine
unthriftiness
enteritis
colic
what animals are affected by A. perfoliata and when?
all ages infected (<3 years old have highest levels of infection)
peak levels detected in autumn/winter but possible all year round
how do we diagnose A. perfoilata?
eggs in faeces - FEC (sensitivity is 60%)
ELISA to detect circulating antibody (sensitivity 68%, specificity 95%)
EquiSal saliva test - improved sensitivity, antibody based
how do we treat A. perfoliata?
double dose pyrantel
praziquantel
what are the ascarid nematodes?
large white roundworms, adults found in small intestine
what are general features of ascarid nematodes?
females lay huge numbers of eggs
eggs are highly resistant
L2/L3 develop in the egg and are the infective stages
direct life cycle
hepato-tracheal migration - stimulates profound inflammatory response
adult worms can cause mechanical blockage
no damage to mucosa
what is Parascaris equorum?
the ascarid of horses and donkeys, common world wide
what is the life cycle of Parascaris equorum?
eggs passed in faeces
develop on the ground (approx 4 weeks) - temperature dependent
egg containing L2/3 is eaten by horse
L2/3 migrates to liver and lung
coughed up and swallowed, L4-5 in small intestine
PPP = 12 weeks
what animals are usually affected by Parascaris equorum?
typically affects foals - adult horses usually immune
what are clinical signs of Parascaris equorum infection?
transient cough
poor weight gain and unthriftiness
no diarrhoea
possible obstruction in heavily infected individuals
how do we control Parascaris equorum?
anthelmintic treatment
drug resistance is reported to ivermectin, moxidectin (possibly also BZ and PYR)
what is oxyuris equi?
horse pinworm, found in large intestine, causes ‘anal rust’
what is the appearance of oxyuris equi?
pointed tails
1-10cm
eggs 80um
what is the lifecycle of oxyuris equi?
direct
female lays eggs on peri-anal skin
eggs fall to the ground
develop to L3 in the egg (approx 5 days)
ingested by horse
larvae develop in mucosal crypts in large intestine
adults in lumen of large intestine
PPP = 5 months
what are clinical signs of Oxyuris equi?
pruritis
excoriation (tail)
how do we diagnose Oxyuris equi?
eggs on perianal area
sellotape / scotchtape test
how do we control Oxyuris equi?
anthelmintics - challenging due to lack of efficacy and rapid reinfection
high hygiene environment reduces transmission