20. Horse Arthropods and Protozoa

Question 1

What is the epidemiology of EPM?

Answer 1

Only in N and S america
seroprevelence - S neurona ranges from 15-89% (USA) and N.hughesi much lower (<10%)
young (<5yrs) and old (>13yrs)
Usually sporadi and only 1 horse/farm
stress trigger (heavy exercise, transport, injury, surgery, birth and lactation)

Question 2

What is sarcocystis neurona?

Answer 2

DH: opossum\IH: skunks, raccoons, armadillos, cats, birds|Horse is aberrant IH - merozoits in neural tissue cause pathology

Question 3

What is neospora hughesi?

Answer 3

DH: unknown - wild canid?
IH: wildlife?, horses (true IH, develops tissue cysts)
Tissue cysts w/ brady zoites associated w/ pathology in horses
transplacental transmission important, occurs in multiple pregnancies
Only ~1/10 positive horses develop EPM

Question 4

How do we diagnose EPM in horses?

Answer 4

can be asymptomatic, high variable - dysphagia, lameness, seizures, muscle wasting, ataxia
Most consistent: asymmetric gait and focal muscle
atrophy
1) Neurological exam
2) Rule out other causes (non febrile, no pain)
3) Definitive antemortem diagnosis is a high CSF:
serum antibody ratio
– Many horses are seropositive for antibodies to S. neurona
* Definitive PM diagnosis:
– IHC or PCR on CNS

Question 5

How do we manage EPM in horses?

Answer 5

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