Equine- Stomach Worms, Parascaris, Strongyloides, Oxyuris and Dictyocaulus Flashcards
What are Equine Differences to felines and canines? (parasites)
Consume parasites on pasture
Higher tolerance for parasites
Fewer concerns with zoonosis
Drug residues – meat?
Why is the diagnosis of parasites important in the equid?
Health
Performance
Financial savings
Draschia megastoma Habronema spp. Identification of adults?
Distinct buccal cavity
Draschia megastoma: 13 mm
Habronema spp.: 22-25 mm
Draschia megastoma Habronema spp. Identification of eggs?
Thin-shelled, larvated
40-55 x 8-16 μm (narrow)
Draschia megastoma Habronema spp. Life cycle?
Indirect Intermediate hosts: Diptera: Muscidae Musca spp. Stomoxys calcitrans
Draschia megastoma Habronema spp. Site(s) of infection?
Adults and larvae in stomach
L3 in skin = “wrong place at wrong time”
Draschia megastoma Habronema spp. Pathogenesis and lesions:in Adults?
Nodules in stomach (D. megastoma adults near
margo plicatus)
Draschia megastoma Habronema spp. Pathogenesis and lesions:in Larvae?
Cutaneous habronemiasis/Cutaneous draschiasis
Granular conjunctivitis
Draschia megastoma Habronema spp. Clinical signs?
Adults cause gastritis
Larvae cause “summer sores”
Draschia megastoma Habronema spp. Diagnosis?
Recovery of eggs in feces difficult
Larvae in scraping of skin lesions
Draschia megastoma Habronema spp. Treatment and prevention?
MCLs approved
Fly control
Reports of ivermectin no longer effective
Resistance?
What is Ascarids Characteristics?
Large white nematodes with 3 lips
What is Cat and dog ascarids?
Toxocara canis, T. cati and Toxascaris leonina
What is Ascarids Infective stage?
L2 in egg
What is Ascarids Life cycle
Direct life cycle
What is Ascarids Location?
Small intestine; hepatic-tracheal migration (not
T. leonina)
What is Ascarids Eggs?
thick-walled (resistant)
What is Ascarids Age of host?
Fecund females
Infect young animals
What is Ascarids Clinical signs?
Obstruction, pot belly
What is Parascaris equorum Identification?
Large nematodes; up to 30 cm
Three lips
Thick walled eggs; 90 μm
What is Parascaris equorum Life cycle?
PPP 10-12 wk
Direct and per os
No transmammary or transplacental transmission
What is Parascaris equorum Site(s) of infection?
Adults in small intestine
What is Parascaris equorum Pathogenesis and lesions?
Perforation, obstruction
Unthriftiness/production losses
What is Parascaris equorum Clinical signs?
Unthriftiness with moderate/heavy infections
Coughing during migratory phase
What is Parascaris equorum Diagnosis?
Fecal exam (simple flotation or Modified McMaster) for eggs Eggs may be absent in spite of clinical signs
What is Parascaris equorum Treatment and prevention?
Several anthelmintics
Resistance to some MCLs
Timing is important
What is Strongyloides spp. Family?
Rhabditidae
What is Strongyloides spp. Common name?
Threadworm
What is Strongyloides spp. Infective stage?
L3
What is Strongyloides spp. Life cycle?
Homogonic/ Heterogonic
What is Strongyloides spp. Eggs?
30 x 40 μm w/L1
What is Strongyloides spp. Dog/cat species?
S. stercoralis
What is Strongyloides spp. Other?
Short PPP; young animals
What is Strongyloides westeri Identification?
Slender hair-like worms, 1 cm
Long esophagus; 1/3 body length
Thin shelled larvated egg 30-40 μm
What is Strongyloides westeri Life cycle?
Per os
Percutaneous
Transmammary (by 4th d)
What is Strongyloides westeri Site(s) of infection?
Adults in small intestine
Larvae in somatic tissues (arrested)
What is Strongyloides westeri Pathogenesis and lesions?
Erythematous reaction where larvae penetrate the skin
What is Strongyloides westeri Clinical signs?
Larvae cause urticaria (“frenzy” reported)
Adults cause diarrhea (young horses; older equids possible)
What is Strongyloides westeri Diagnosis?
Fecal flotation methods
Expect to see in < 5 mo old horses
What is Strongyloides westeri Treatment and prevention?
Incorporated with control of Strongyles and ascarids, since normally not a critical parasite
What is Strongyloides spp. in Equids?
S. westeri
What is Oxyuris equi Common name?
large pinworm
What is Oxyuris equi Identification?
Long, white, pointed tail, up to 10 cm
Normally only females seen
What is Oxyuris equi Life cycle?
(PPP 4-5 mo)
Adults in dorsal colon
Female migrates through anus to lay eggs around perineum
Eggs laid with gelatinous substance (irritant)
Larva develops to L3 in egg; egg with L3 infective stage
L3 develop to L4 and adults
What is Oxyuris equi Site of infection?
Adults live in large intestine
What is Oxyuris equi Pathogenesis?
Pruritus
What is Oxyuris equi Clinical signs?
Peri-anal irritation (from eggs and gelatinous substance)
What is Oxyuris equi Diagnosis?
Broken hair at tailhead
Adhesive tape method or perianal scrapings method
What is Oxyuris equi Treatment and prevention?
MCLs, FBZ, etc.
Resistance suspected
What is Dictyocaulus arnfieldi Hosts?
Donkeys
In horses adults do not reach sexual maturity and patency
What is Dictyocaulus arnfieldi Identification?
Slender nematodes in bronchi 8 cm long
What is Dictyocaulus arnfieldi Life cycle?
Adult stages in bronchi lay eggs containing L1
Eggs hatch in lungs and in feces; eggs and L1 found in feces
Develop to L3, migrate from feces to herbage where ingested
What is Dictyocaulus arnfieldi Pathogenesis and lesions?
Damage to pulmonary tissue
What is Dictyocaulus arnfieldi Clinical signs?
No clinical signs in donkeys
What is Dictyocaulus arnfieldi Diagnosis?
L1 recovered in fresh feces and lung washings
Adults in lungs at necropsy
What is Dictyocaulus arnfieldi Treatment and prevention?
In endemic areas do not pasture horses and donkeys together
