EEE. It's Here!

Last week I talked with a veterinarian friend in southwest Michigan who mentioned that he had recently seen a case of suspected EEE. As of 2 days ago, there were 3 confirmed cases of EEE in horses in SW Michigan, as well as several other highly suspicious cases, that are awaiting the completion of further testing to confirm the diagnosis. Infected horses have been identified in Cass, Barry & Calhoun counties.

Veterinary medicine is notorious for using letter abbreviations for disease names. This alphabet soup may seem a little silly, but with diseases like Eastern Equine Encephalitis you can see why we all call it EEE. The more common name for this disease is Sleeping Sickness. That name is a bit of a misnomer since it implies a peaceful, resting state. It is anything but. This is a very nasty disease, characterized by neurologic deficits with symptoms including fever, depression and weakness that rapidly progress to lack of coordination, head pressing, a “sawhorse” stance, circling, paddling and/or convulsions. Affected horses can be very irritable with aggressive behavior, they may be excitable, blind, and/or have abnormal sensitivity light and sound. 75 to 90% of affected horses will die from the disease.

It can be difficult to sort out EEE from some other neurologic diseases. Rabies is the most significant other possibility for horses exhibiting these symptoms. Other possibilities include West Nile Virus, Western EE and Venezuelan EE (VEE is not know to exist in the northern regions of the U.S.) Because of the potential human health concerns with these viruses, definitive conformation of the disease is critically important. While there are blood tests for some of these diseases, a brain specimen (post mortem) is required to definitively confirm the diagnosis.

The fortunate thing about EEE, WEE, WNV & Rabies is that we have very effective and safe vaccines readily available to prevent infection. The caveat to vaccination is that they must be properly administered using a properly handled and stored product well in advance of exposure to the bug. Immunization against these diseases is a staple of our current vaccine programs. These are vaccines all horses should always get, every year, regardless of where they go or what they do. Vaccination is by far and away the most effective single measure to undertake to prevent infection.


EEE, WEE, and WNV all are viral diseases transmitted by mosquitoes. Because of that, we usually do not start to see cases until late summer (August or September) because it takes a while to get enough virus circulating through mosquitoes to result in an infection. EEE is carried by birds, that usually are not affected by the virus. Mosquitoes bite the bird and then transmit it to horses or humans. Because mosquitoes are the major vector in the spread of the disease, measures to control the mosquito population are crucial to successful control strategies. But given that several cases have been reported while it is still relatively early in the summer, means that we are sure to see more cases as the summer progresses.

The other reason these disease are of such great concern is that humans can also be affected. With EEE, affected horses are not a source of infection to people or other animals, but Rabies certainly can be. That said, if a horse is affected with EEE it is a pretty good indicator that the virus is present in the mosquito population in that area. So other horses in the same proximity are certainly at risk as well.

One of the scariest things about these cases, is that it is still relatively early in the summer to start to see this mosquito vector borne disease. The importance of proper vaccination cannot be overemphasized. It is not too late to get your horse(s) vaccinated if it has not already been done. Annual vaccination is considered protective. The other disease prevention strategies really center around limiting exposure to mosquitoes. This has been a very wet summer, especially in SW Michigan, where these cases are emerging. It would be prudent to eliminate sources for standing water around your barn or property. Bringing horse into the barn, especially around dusk can be helpful as well. Fly and mosquito sprays can be beneficial, but none of them seem to last very long. Stay tuned for further updates.

All In the Name of Progress

Last week I had the opportunity to spend a day at Horse Progress Days in Topeka, IN. Okay, so it may not quite be on the same plain as the upcoming Word Equestrian Games, but it is a pretty fun event. It is traditionally the Friday and Saturday before the 4th of July. The event draws in excess of 10,000 people each day. The idea behind Horse Progress Days is to showcase innovations revolving around the use of horses in agriculture. Because of that, the annual event has a strong Amish influence.

There are not a lot of places you can go anymore to see a hitch of 18 horses pulling a 4 bottom plow, or a hitch of four abreast baling hay, or a team dragging a 30 foot log. Horse Progress Days is the place that affords those opportunities. There are also many seminars throughout the day on draft horse related topics. Attendees also are give the opportunity to drive a team of horses, regardless of past experience. Of course there is also a large trade show of numerous vendors showcasing anything and everything related to draft horse and farming with horses. The highlight of the event is the breed presentation at the end of the day. This showcase gives all those is attendance a brief history and demonstration of almost all breeds used for draft, including some light horses, like Morgans, Arabians, Saddlebreds, Dutch Harness horses, and pretty much all of the draft breeds- even the fairly uncommon ones.

The ‘homemade’ ice cream is always a crowd favorite. The reason I put ‘homemade’ in quotes is that, as you can see in the picture below, the people in the tent are tending to the ice cream machine being powered by horse on a treadmill, and the dozen or so empty boxes of GFS soft serve ice cream mix!

This really is a fun, family friendly event that gives the opportunity to see how farming with horses really works. Next year’s event is in Lancaster, PA. For more info check out horseprogressdays.com

COW (Case of the Week): Glaucoma

Here is a picture of a horse I saw a week or so ago. This is probably one of the most extreme examples of an eye with chronic glaucoma that I have seen in quite a while. Glaucoma is when the pressures inside the eye become much higher than they should be. As you can see in the picture, the left eye is considerably larger than the right. The left eye has become so large as a result of chronically high pressures within the globe. When an eye experiences this much damage they are difficult to salvage.

This horse reportedly has had a long standing history of ‘eye problems.’ Most cases of glaucoma in horses are the result of uveitis, as was the case with this horse. There are many different things that can cause uveitis in horses, but the most common form is recurrent uveitis or ‘moon blindness.’ Glaucoma is a condition that usually develops as a consequence of uveitis. It is critically important to evaluate these ‘eye problems’ early on in the course of the disease. When an eye reaches this stage, it is impossible to undo all of the damage that has been done.

Eye problems in horses should not be taken lightly. It is critically important to treat these cases early and aggressively. Diseases of the eye are also extremely difficult to sort out over the phone. We commonly get phone calls from clients asking what they should treat a watery or swollen eye with. It is not possible for us to make treatment recommendations without examining the eye, because one medication that might be the right treatment for one condition could be the absolutely wrong treatment for the other. A good treatment plan always starts with a diagnosis.