Horses Flashcards
Small intestine nematode of horses
Parascaris equorum
- Family ascarididae
- Large roundworm of horse
Strongyloides westeri
- Equine threadworm
ecology/epidemiology of parascaris
Primary in foals <6 months of age
Occasionally present in adult horses, often aged
In SK study 50% of foals shedding vs 3% of mares
Worldwide distribution
Pastured and stable animals
Eggs very resistant and sticky and lots
Life cycle of parascaris equrum
PPP ~10-12 weeks
Eggs with morula in feces
Take at least 3 weeks to mature in enviro
Ingest eggs with L3
Heptotracheal migration
ecology/epidemiology of Strongyles westeri
Primarily in foals <6 months of age
Worldwide distribution
Warm humid climates
Pastured and stable animals with suboptimal environmental hygiene
Eggs nor particularly resistant
Vertical transmission (transmammary)
Larvae shed in milk for up to 8 weeks
Diagnosis on fecal floatation with fresh foal feces
Life cycle of strongyles westeri
PPP 10-14 days
L3 is infective stage
Can be eaten or go through skin
Can survive whole lifecycle in environment
Semitracheal and treacheal migration on foals
can have somatic migration in adults and be transmitted through colostrum and milk
Pathogenesis of strongyloides in horses
Cutaneous lesions possible
Respiratory signs possible
Big one is diarrhoea in young foals (as young as 2 weeks)
If known problem; treat mare just before foaling to prevent transmammary transmission and foals at about 1 week of age
Migratory large strongyles common in horses are
Strongylus vulgaris- bloodworm
Strongylus endentatus
Strongylus equininus
Are strongyles common in horses and how to diagnose
Virtually eradicated worldwide due to sue of modern anthelmintic
These worms are apstrue transmitted
Diagnosis
Strongyle type eggs in fecal floatation
Life cycle of Stringylus vulgaris
PPP ~6mos
L3 infective
Direct lifecycle through ingestion
Mesenteric artery migration
Strongylus equinus lifecycle
PPP around 1 year
L3 infective
Liver/pancrease migration
Strongylus endentatus life cycle
PPP around 1 year
L3 infective
Liver/pancrease migration
Cyathostomins is and how is it transmitted
small strongyles
Most abundant and diverse equine nematodes
At least 60 known species
Pasture transmitted
Cyathostomes life cycle
PPP 2-3 mo
L3 infective is ingested
Mucosal migration
What should you consider when deworming your horse
Individual horse susceptibility and overall health
Geography
Pasture vs Stable
Number of horses per acre
Pasture management
Any known resistance
Owner risk tolerance
The Future – what will vets and horse owners have that still works in 10 years? 20 years?
Pasture and manure management for horses
Don’t relocate recently dewormed horses to “clean” pasture
Reduce stocking density
Dispose of manure regularly (twice a week)
Feed off (above) the ground
Do not spread fresh manure on fields that horses are grazing (compost will kill most eggs if high enough temperature)
Mow and harrow pastures periodically
Separate weanlings from yearlings, adults
Oxyuris equi is located where in the horse and where in canada
Located in the large intestine
Caecum, colon, rectum, perianal region
Pinworm of horses
Worldwide distribution including western Canada
Stabled horses, poor hygiene
Eggs environmentally resistant
NOT ZOONOTIC
What are the clinical signs. tx/dx of Oxyuris equi
Have itchy bums
Dx: rarely flotation, usually swab or tape mount from perianal region
Tx: hygiene (environment and perineal washing), many labeled products
Dictyocaulus arnfieldi is located where and common in
Located in the lungs
Order Strongylida
Rare in Canada
Dyspnoea and cough
Not no eggs from adult horses – primary reservoir is donkeys
Pasture transmitted
Dictyocaulus arnfieldi lifecycle
PPP 12-14 weeks
3rd stage larvae infective
Tracheal migration to lungs
Cestodes of horses
Anoplocephala perfoliata–Ileum and Caecum
Most common species
Anoplocephala magna–proximal SI
Paranoplocephala mammillana – proximal SI
Worldwide distribution, rare in western Canada
Pasture transmitted
What are the c/s/dx/tx of equine tapeworms
Clinical signs: often none
Foals with other health issues
Risk factor for ileal impaction and spasmodic colic (A. perfoliata)
Dx: eggs in feces 24 hrs post-treatment
Tx: Single annual treatment with praziquantel in late fall
Archinda of equines
Mites and ticks
Insecta of equines
Lice (O.Phthiraptera)
Sub O. Mallophaga CHEWING
Sub O. Anoplura SUCKING
Flies (O. Diptera)
Mites of equines
Chorioptes bovis
Surface Mite – Horses, cattle
“heel mite, foot mange”
Diagnosis of chorioptic mange in horses
History and clinical appearance
Can be totally asymptomatic
Pruritus of pastern, heel, and feathers
Pruritis of tailhead
Superficial skin scraping with KOH digest
Treatment and control of Chorioptic mange in horses
Highly contagious (treat all in herd and in-contact cattle & sheep)
What are common ticks seen on horses and in what time of year
Dermacentor albipictus (1H)
- Seen in winter
- L,N,A ticks
Dermacentor variabilis (3H)
- Adult seen in spring
Dermacentor andersoni (3H)
- Adults seen in spring
Ixodes species (3H)
- Adult seen in fall
Tick borne diseases in horses are rare in Canada
Diagnosis of ticks on horses
Direct observation/clinical appearance
Collect and store fresh, frozen or ethanol
Identify to genus level
Test for tick-borne pathogens IF CLINICAL
Treatment and control of ticks on horses
Manual removal (within 12-24 hrs)
Environmental modification
Topical Repellents: sprays, wipes, powders (carbaryl, pyrethroids, permethrin…)
What are the common lice of horses
Damalinia equi- chewing louse
Dorso-lateral trunk
Haematopinus asini– sucking louse
Mane, tailhead and fetlocks
Egg is at the BASE of hair
Diagnosis of lice in horses
History and clinical appearance
Often asymptomatic (Carriers)
Hair loss, irritation, pruritus, dandruff (anemia)
Nits on base of hair, recovery and ID of adult lice
Treatment of lice in horses
Topical pesticides: sprays, wipes, powders, shampoos (carbaryl, pyrethroids, permethrin…)
Systemic/oral ML may work on sucking lice
Treat repeatedly (also fomites)
Highly contagious (treat all horses in herd)
Flies common on horses
Diptera
Bot flies
[Other myiasis Flies]
[Non-Biting Flies]
Blood-Feeding Flies
Bot flies of horses
Gasterophilus intestinalis: eggs on forelimbs and shoulders, L3 in cardiac region of the stomach
Gasterophilus nasalis: eggs in inter- mandibular region, L3 in pylorus and proximal duodenum
Gasterophilus haemorrhoidalis: eggs on hair of mouth and lips, L3 in rectum
Gastrophilus sp adults have no mouth parts and do not feed
Eggs are on the tips of hair
Diagnosis of bots in horses
Usually asymptomatic
High intensities anorexia, colic, anaemia
Eggs on tips of hair (vs base)
L3 on gastroscopy, passed in feces, post-mortem
Treatment of bots in horses
Ivermectin or moxidectin in fall after first frost
Blood feeding flies of horses are
Stomoxys calcitrans – Stable fly
Culicoides spp. – Midge
Hypersensitivity to salivary antigens (Queensland or sweet itch)
Tabanids– Horse fly, Deer fly, Clegs
Culex, Aedes, Anopheles– Mosquitos
IH/biological vectors for Setaria, West Nile virus, Equine Encephalitis (WEE, EEE, VEE)
Management of biting flies for horses
Stabling schedule and hygiene
Screens (fine mesh for Culicoides)
Site selection for grazing and manure piles
Eliminate arthropod breeding sites (water)
How do you control biting flies in horses
Topical Repellents: sprays, wipes, powders, back rubbers (malathion, pyrethroids, permethrin…)
Do not work for tabanids
Pesticides, do not use off label
Wound care to prevent myiasis
Apicomplexa– coccidia of the horse
Eimeria leuckarti
Eimeria leuckarti is how common and what are the c/s
Prevalence ~40% in foals
Non-pathogenic
Diarrhea rare
No Tx approved or needed
Equine protozoal Myeloencephalitis (EPM) is and is caused by
Equine IH/PH/AH
Sarcocystis neurona*
Neospora hughesi
*most common cause of EPM
Clinical signs of EPM
Weakness
Muscle atrophy
Ataxia
Seizures
Cranial nerve deficits
Lameness
Epidemiology of EPM
Only in north and south america
Seroprevalence
S. neurona ranges from 15-89% (USA)
N. hughesi much lower (<10%)
Young (<5 years) and old (>13 years)
Usually sporadic, only 1 horse/farm
Stress trigger (heavy exercise, transport, injury, surgery, birth and lactation)
Sarcocytis neurona DH and IH are
DH: opossum
IH: skunks, racoons, armadillos, cats, birds…
Horse is aberrant IH
Merozoites in the neural tissue cause the pathology
Neospora hughesi hosts are and what type of migration is
DH: unknown – wild canid?
IH:Wildlife?,Horses (True IH, develops tissue cysts)
Tissue cysts with bradyzoites associated with pathology in horses
Transplacental transmission important, occurs in multiple pregnancies
Only ~1/10 positive horses develop EPM
Diagnosis of EPM in horses
Can be asymptomatic, highly variable
Dysphagia, lameness, seizures, muscle wasting, ataxia
Most consistent: asymmetric gait and focal muscle atrophy
Neurological exam
Rule out other causes (non febrile, no pain)
Definitive antemortem diagnosis is a high CSF: serum antibody ratio
Many horses are seropositive for antibodies to S. neurona
Definitive EPM diagnosis:
IHC or PCR on CNS
What does EPM stand for
Equine protozoal Myeloencephalitis (EPM)
Management of EPM in horses
Do Treat! (10 times more likely to improve)
Variety of anti-coccidial drugs are available
Duration 6-8 weeks, longer if still improving
May relapse
NSAIDS
Prevent contamination of horse feed and water
