AHL LabNote 55-Handling submissions requesting Equine neurological disease testing

Many clients are not familiar with testing for equine neurological disease and may ask for testing that will not provide the answers that they are looking for leading to difficulty in interpretation.

Rabies: may be on the list of rule outs. This may affect handling of fluids and tissues depending on what is submitted. If rabies is suspected (Check box or discussion with the client) please make sure that they are following up with Public Health (human involvement) or OMAFRA (animal involvement only).

Test

Code

Sample

Note

Zoonotic

Ehv-1 Herpes (See Labnote 20)

Equid herpesvirus 1-PCR

(Test of Choice)

ehv12

EDTA blood and/or

nasal swab( VTM or swab in blood tube)  preferably both EDTA blood  and swab)

This test is NOT a PCR for EHV-2 (send out to Idexx)

N

West Nile Virus-PCR

wnvpn

Brain in tripure for PCR

If dead

Y

West Nile Virus IgM Elisa

xwnveq

Serum

If live sent to USDA longer TAT

Y

Eastern Equine Encephalitis (EEEV)-PCR

eeepn

Brain in tripure for PCR

If dead

Y

Eastern Equine Encephalitis (EEE) IgM Elisa

xeeevme

Serum

live horse

Sent to USDA longer TAT

Y

Sometimes clients ask for Virus Neutralization testing (VN) (EHV ¼, WNV, EEE, WEE.  This is fine if they are looking for titres and vaccination status (Please note there are no validated guidelines for titre testing in horses) but unsuitable for acute onset testing. The only way to use titres for diagnosis is acute and convalescent titres 3-4 weeks apart submitted together for VN (a four fold rise in titre denotes infection).

Equine encephalitis virus, Eastern-PRNT

(EEEV VN)

xeeevvn

serum

USDA longer TAT

Y

Equine encephalitis virus, Western - PRNT

xweevvn

serum

USDA longer TAT

Y

WNV VN

xwnvvn

serum

USDA longer TAT

Y

 

EPM – Equine Protozoal Myelitis may also be on the list and practitioners may have their own preferred method of testing.  Our standard test is:

EPM, S. neurona SAG2,4/3 titer, serum - ELISA

xepme

serum

Sent to EDS longer TAT

this is not a definitive test and only denotes exposure

N

Jim Fairles