Buttercup CC Answer!

Good job anonymous! You guessed EHV-1, which was the correct answer.

CJ - EEE was a good guess - that's one reason I put a month and location - fever + neuro are very vague signs, however outbreaks that are occuring near you should be taken into consideration when trying to think of likely causes. EEE in Feb (mosquito bourn) with no outbreaks.......Or EHV-1 (direct horse to horse or through shared equipment) with known cases in the state you are?

Hannah - I left the city vague on purpose because although if the horse was in Gurnee, IL it would be a HUGE red flag for the vet and the owner, It should be a redflag even if you AREN'T in Gurnee. For those of you that haven't been following the EHV-1 cases, there were some cases of horses with EHV-1 specifically located in Gurnee IL.

EHV-1 is diagnosed all over the country all the time - it just isn't always associated with an outbreak. Thus, even when EHV-1 isn't at the forefront of our minds, it's still a reasonable differential diagnosis in a horse with a history of show travel, or use of facilities where many horses are coming and going. I was suprised to see on the CDFA website the number of CA cases over the last couple of years, most of which are not related to each other.

This week cases in California and Montana were announced that are related to the current outbreak. According to my source (Promed) affected states currently include Utah, Colorado, Tennessee, New Jersey, Florida, Minnisota and Illinois. Because of horse/livestock travel, non-vector bourn disease such as this one can make odd leaps and won't necessarily have a predictable march through the states. Don't assume that just because a particular disease has been isolated to the midwest, that it won't appear suddently on the west coast.

I've been keeping an close eye on the EHV-1 situation because although the vaccine isn't completely protective against this varient, I will pop Farley with a 4 way influenza combo if it get close since it may be partially protective. So far cases have popped up in LA and San Diego counties, which are so far away it's basically in another state, so I'm not worried yet. A single case in each county.

A bit about the disease

EHV-1 stands or "equine herpesvirus type 1". Transmission is usually via aerosols, when horses cough and sneeze, however it can also be spread through sharing equipment like bits and buckets.

The presentation of the disease an vary. A "rhinopneumonitis" (persistant cough, snotty nose) typically in young horses, abortion in broodmares, and the "neuro" form (incontininance, ataxia, incoordination, paralysis of hind limbs, fever, death). There is a vaccine available for the first two forms, however the vaccine does NOT seem to be effective against the neuro form.

The terminology can be a little confusing. The "neuropathogenic" strain/mutation is a form of the EHV-1 that can cause the neuro signs and death and is the one that we most worry about in the outbreaks. Sometimes you might see it referred to as "nEHV-1" to try and differentiate the neurotrophic form from the other type. The other EHV-1 "just" causes the typical rhino and abortion issues, however in a very small percentage of cases it can also cause neuro signs!

A confirmed case of EHV-1 is one of two scenerios:

1. A horse has compatible clinical signs (one or more: fever, recumbancy, snotty nose, ataxia, hind end weakness, diminished tail tone) AND a lab test positive for the neuropathogenic strain of EHV-1.

OR

2. A horse has neuro signs AND a lab test positive for any strain of EHV-1

For example, the CA San Diego case is a stallion that displayed mild neuro signs AND has a positive test for EHV-1 (a NON-neuropathogenic strain). Even though it was not the neuropathogenic type, in CA EHV-1 with neuro signs regardless of strain is still a "reportable" disease. The LA CA case was a more typical nEHV-1 that showed the typical clinical signs, and had a positive nEHV-1 test.

The current recommendation by state vets in states affected is to start temping horses that are going to an equine event 3 days prior to travel, and continue to temp daily until 3 days after the event. Horses with a temperature over 103*F should be isolated and not allowed to mingle with other horses (CA's cdfa website says 102*F and it wants you to contact a vet). Keep in mind that temperature can elevate in a horse that is being exercise, no you are looking for an increased temperature that is NOT related to working the horse.

The disease is edemic to the US, with the federal government becoming in involved when outbreaks involve multiple states.

This disease is an important example of why I do not allow other people's horses to say "hello" to mine at events. It's high contagiousand there's no effective vaccine. Horses aren't offended if their neighbor doesnt say hello and it might save her life and me a lot of grief.

Check in next Wednesday for the case of "Chester".

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