Horses

Question 1

Small intestine nematode of horses

Answer 1

Parascaris equorum
- Family ascarididae
- Large roundworm of horse
Strongyloides westeri
- Equine threadworm

Question 2

ecology/epidemiology of parascaris

Answer 2

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

Question 3

Life cycle of parascaris equrum

Answer 3

PPP ~10-12 weeks
Eggs with morula in feces
Take at least 3 weeks to mature in enviro
Ingest eggs with L3
Heptotracheal migration

Question 4

ecology/epidemiology of Strongyles westeri

Answer 4

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

Question 5

Life cycle of strongyles westeri

Answer 5

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

Question 6

Pathogenesis of strongyloides in horses

Answer 6

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

Question 7

Migratory large strongyles common in horses are

Answer 7

Strongylus vulgaris- bloodworm
Strongylus endentatus
Strongylus equininus

Question 8

Are strongyles common in horses and how to diagnose

Answer 8

Virtually eradicated worldwide due to sue of modern anthelmintic
These worms are apstrue transmitted
Diagnosis
Strongyle type eggs in fecal floatation

Question 9

Life cycle of Stringylus vulgaris

Answer 9

PPP ~6mos
L3 infective
Direct lifecycle through ingestion
Mesenteric artery migration

Question 10

Strongylus equinus lifecycle

Answer 10

PPP around 1 year
L3 infective
Liver/pancrease migration

Question 11

Strongylus endentatus life cycle

Answer 11

PPP around 1 year
L3 infective
Liver/pancrease migration

Question 12

Cyathostomins is and how is it transmitted

Answer 12

small strongyles
Most abundant and diverse equine nematodes
At least 60 known species
Pasture transmitted

Question 13

Cyathostomes life cycle

Answer 13

PPP 2-3 mo
L3 infective is ingested
Mucosal migration

Question 14

What should you consider when deworming your horse

Answer 14

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?

Question 15

Pasture and manure management for horses

Answer 15

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

Question 16

Oxyuris equi is located where in the horse and where in canada

Answer 16

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

Question 17

What are the clinical signs. tx/dx of Oxyuris equi

Answer 17

Have itchy bums
Dx: rarely flotation, usually swab or tape mount from perianal region
Tx: hygiene (environment and perineal washing), many labeled products

Question 18

Dictyocaulus arnfieldi is located where and common in

Answer 18

Located in the lungs
Order Strongylida
Rare in Canada
Dyspnoea and cough
Not no eggs from adult horses – primary reservoir is donkeys
Pasture transmitted

Question 19

Dictyocaulus arnfieldi lifecycle

Answer 19

PPP 12-14 weeks
3rd stage larvae infective
Tracheal migration to lungs

Question 20

Cestodes of horses

Answer 20

Anoplocephala perfoliata–Ileum and Caecum
Most common species
Anoplocephala magna–proximal SI
Paranoplocephala mammillana – proximal SI
Worldwide distribution, rare in western Canada
Pasture transmitted

Question 21

What are the c/s/dx/tx of equine tapeworms

Answer 21

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

Question 22

Archinda of equines

Answer 22

Mites and ticks

Question 23

Insecta of equines

Answer 23

Lice (O.Phthiraptera)
Sub O. Mallophaga CHEWING
Sub O. Anoplura SUCKING
Flies (O. Diptera)

Question 24

Mites of equines

Answer 24

Chorioptes bovis
Surface Mite – Horses, cattle
“heel mite, foot mange”

Question 25

Diagnosis of chorioptic mange in horses

Answer 25

History and clinical appearance
Can be totally asymptomatic
Pruritus of pastern, heel, and feathers
Pruritis of tailhead
Superficial skin scraping with KOH digest

Question 26

Treatment and control of Chorioptic mange in horses

Answer 26

Highly contagious (treat all in herd and in-contact cattle & sheep)

Question 27

What are common ticks seen on horses and in what time of year

Answer 27

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

Question 28

Diagnosis of ticks on horses

Answer 28

Direct observation/clinical appearance
Collect and store fresh, frozen or ethanol
Identify to genus level
Test for tick-borne pathogens IF CLINICAL

Question 29

Treatment and control of ticks on horses

Answer 29

Manual removal (within 12-24 hrs)
Environmental modification
Topical Repellents: sprays, wipes, powders (carbaryl, pyrethroids, permethrin…)

Question 30

What are the common lice of horses

Answer 30

Damalinia equi- chewing louse
Dorso-lateral trunk
Haematopinus asini– sucking louse
Mane, tailhead and fetlocks
Egg is at the BASE of hair

Question 31

Diagnosis of lice in horses

Answer 31

History and clinical appearance
Often asymptomatic (Carriers)
Hair loss, irritation, pruritus, dandruff (anemia)
Nits on base of hair, recovery and ID of adult lice

Question 32

Treatment of lice in horses

Answer 32

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)

Question 33

Flies common on horses

Answer 33

Diptera
Bot flies
[Other myiasis Flies]
[Non-Biting Flies]
Blood-Feeding Flies

Question 34

Bot flies of horses

Answer 34

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

Question 35

Diagnosis of bots in horses

Answer 35

Usually asymptomatic
High intensities anorexia, colic, anaemia
Eggs on tips of hair (vs base)
L3 on gastroscopy, passed in feces, post-mortem

Question 36

Treatment of bots in horses

Answer 36

Ivermectin or moxidectin in fall after first frost

Question 37

Blood feeding flies of horses are

Answer 37

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)

Question 38

Management of biting flies for horses

Answer 38

Stabling schedule and hygiene
Screens (fine mesh for Culicoides)
Site selection for grazing and manure piles
Eliminate arthropod breeding sites (water)

Question 39

How do you control biting flies in horses

Answer 39

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

Question 40

Apicomplexa– coccidia of the horse

Answer 40

Eimeria leuckarti

Question 41

Eimeria leuckarti is how common and what are the c/s

Answer 41

Prevalence ~40% in foals
Non-pathogenic
Diarrhea rare
No Tx approved or needed

Question 42

Equine protozoal Myeloencephalitis (EPM) is and is caused by

Answer 42

Equine IH/PH/AH
Sarcocystis neurona*
Neospora hughesi
*most common cause of EPM

Question 43

Clinical signs of EPM

Answer 43

Weakness
Muscle atrophy
Ataxia
Seizures
Cranial nerve deficits
Lameness

Question 44

Epidemiology of EPM

Answer 44

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)

Question 45

Sarcocytis neurona DH and IH are

Answer 45

DH: opossum
IH: skunks, racoons, armadillos, cats, birds…
Horse is aberrant IH
Merozoites in the neural tissue cause the pathology

Question 46

Neospora hughesi hosts are and what type of migration is

Answer 46

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

Question 47

Diagnosis of EPM in horses

Answer 47

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

Question 48

What does EPM stand for

Answer 48

Equine protozoal Myeloencephalitis (EPM)

Question 49

Management of EPM in horses

Answer 49

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