Hello there!  Welcome back to my corner.  When it comes to neurological disease in the horse, there are two syndromes you should be familiar with. They are both diseases caused by spinal cord compression in the neck, and can exhibit symptoms very similar to EPM, West Nile Virus, and other infectious causes of neurologic disease. Cervical stenotic myelopathy (CSM), formerly known as “Wobbler’s syndrome,” exhibits two forms – type I and type II.  This week we will discuss Type I CSM, which is the “classic Wobbler’s,” and next week we will discuss type II – seen in older horses as a result of neck (cervical) arthritis.

Type I CSM, also called Cervical Vertebral Malformation, is most commonly seen in horses less than five years of age.  In every species, there is a canal that present in each vertebra, called the spinal canal, that houses the spinal cord. These holes must line up and be of sufficient width to allow the spinal cord to run straight through the spinal column without compression from the bony tunnel.  This is exactly what goes wrong in horse with Type I CSM.  Sometimes the canal in the vertebra narrows, sometimes it is shaped like a cone, or it can be elongated.  These changes are a result of a developmental orthopedic disease in the vertebra, in the same group as OCD, contracted tendons, and bone cysts.  As a result, the horse has compression of the nerves that run along the outside of the spinal cord to their legs.  In general, the nerve compression that occurs is worse in a flexed neck position, and so we call the narrowing “dynamic,” or changing.  Rapid growth and large size are risk factors for this type of CSM, as are high protein and caloric intakes.  There may be a genetic predisposition for this disorder as well. Thoroughbreds, Warmbloods, and Tennessee Walking horses are significantly more likely to be affected than Quarter horses, Standardbreds, and Arabians.

Clinical signs often manifest first as evidence of weakness in the hind end.  This is because the nerves running to the hind legs are to the outside of the nerves running to the front legs in the spinal cord.  Ataxia, spasticity of the limbs, and weakness may start insidiously or suddenly.  Sometimes a history of a fall confuses the diagnosis (was the fall the cause or result?), and clumsiness and tripping is commonly reported.  Changes may first be noticed by your farrier when he is trying to trim the back feet. A pacing gait may also be present. Diagnosis is based on a complete neurologic exam where the neurologic deficit is localized to the neck, followed by neck radiographs.  Sometimes it is necessary to inject contrast dye into the space outside the spinal cord (contrast myelogram), and then radiographs show a narrowed or “pinched off” area where the dye can’t pass through the compressed area.  Often the CSF analysis is normal.

Prevention of Type I CSM is aimed at limiting protein and caloric intake to regulate growth.  Suspected horses less than a year should be weaned and placed on a “Paced Diet,” including free choice grass hay and limited amounts of growth diet and/or ration balancer to provide necessary vitamins and minerals. Foals should be confined to a stall or small paddock to restrict exercise, certainly not free-choice pasture.  Intra-articular (joint) injections with steroids can be performed on the affected neck joints under ultrasound guidance, providing symptomatic relief (will be discussed in more detail next week).  Finally, surgical correction can be performed for affected horses.  A metallic (steel or titanium) cylinder or basket is placed between the vertebrae – the goal is to induce arthritis, fusing the joint between the neck vertebrae (as we fuse hock joints in cases of advanced arthritis).  This makes the joint more stable and minimizes dynamic compression. It has been found to improve the neurologic status in 44-90% of horses with dynamic compression.

Please contact us if you would like more information on diagnosis, prevention, and treatment of CSM Type I. As always, may your litter box be clean, and your food bowl be full.  Thanks for stopping by!

Every time we change clocks around here Dr. Lacher starts to go on and on about checking fecal egg counts on our patients.  It always makes me wonder what happens when they clean my litter box but Dr. Lacher told me she doesn’t work on cats, only snuggles with us.  I did get her to answer about fecal eggs counts on horses and thought I would blog about it this week so here goes:

Around the early 1980s a revolution happened in equine parasite control:  Ivermectin.  With the use of this drug, horse owners could easily and safely remove parasites from their horses on a regular basis.  Doses of up to ten times normal would not cause problems and since it was a new class of drug parasites were annihilated.  Horse owners were happy, horses were happy, drug companies were happy and veterinarians were happy they no longer had to tube deworm.

We traveled along in our little universe until the late 1990s thinking everything was great and fine.  Worms were a thing of the past and we should keep our horses healthy by deworming every 6-8 weeks.  Sure resistance could be a problem but we just rotated products and that was that.

And we were wrong, very, very wrong.

Dewormers all have what is known as an egg reappearance period.  This is the time it takes to begin seeing parasite eggs in a fecal egg count after administering a product.  For Ivermectin this is 6-8 weeks, fenbendazole and pyrantel 4-6 weeks and moxidectin 10-12 weeks.  You should never administer a dewormer sooner than its egg reappearance period and ideally it should be at least double that time frame.  So by using Ivermectin too often we were killing off any and all sensitive parasites and only allowing the ones resistant to treatment to survive.  We were creating super worms!

Most of us do not have these super worms on our properties and can avoid their creation through intelligent deworming using fecal egg counts.  And here is where we get back to changing your clock and checking a fecal.  Turns out in Florida we kill off a tremendous amount of the parasite load during our very hot summers.  Parasite eggs cannot survive prolonged temperatures over 85 degrees.  Once temperatures have decreased below 85 degrees for about 7-10 days in a row we have the potential to drastically increase our horse’s exposure to viable parasites!  This means that if we check a fecal now and determine our horse’s parasite burden we can ensure they are treated effectively through our prime parasite season.  By checking their burden again in the spring we can maximize the effects of a final deworming before warm temperatures decrease the need for drugs.  This allows us to deworm only the horses that need it when they need it with the drug they need.

The next way we minimize resistance among the wee beasites is by keeping a low worm burden in our horses.  “Whoa!” you say my horse is not going to have any worms!!  Our horses were designed to have a low parasite burden and do just fine as long as the numbers don’t get too high.  In fact recent research has shown low levels of intestinal parasites to be important in combating diseases of the immune system.  More importantly for this topic, by keeping a small amount of worms around we ensure that resistant and non-resistant parasites breed, creating offspring who are susceptible to our deworming drugs.  So again, fecal egg counts help us identify only those horses with very high burdens and target only them for therapy.   This reduces the number of parasites exposed to drugs unnecessarily.  This is known as refugia for those scientific types who enjoy spending time on Wikipedia.

Fecal egg counts also allow us to check for resistance to drug classes.  When performing counts we always recommend a recheck fecal on any high shedders 10-12 days after dewormer administration.  This allows us to make sure there was a significant drop in egg counts.  If there isn’t, we know resistant parasites are a problem and we can take steps to address this very serious issue.

Deworming has definitely gone from a one schedule fits all to a customized program for you, your horse and your property.  The Doctors and Technicians at Springhill Equine have been great about answering my questions while I supervise from the counter and I’m sure they would answer yours as well!

That’s all from the countertop this week.  May your litter box be clean and your food bowl full!!

In recognition of this year’s theme for our Third Annual Springhill Equine Open House! Hope to see you Saturday, October 8^th from 10 a.m. to 1 p.m.!

Hurricane Andrew was an eye-opening event for Florida horse owners.    Many horses died in their stalls because their barns collapsed around them, fences failed allowing horses to get out on roadways or tangled in the fencing and wandering horses got electrocuted or suffered severe dehydration looking for water sources.  This led to the Sunshine State Horse Council gathering together information on what worked and didn’t work to save lives.  In this newsletter we have pulled together the most pertinent information for our area and given you a place to start planning.

A huge lesson learned was to be prepared!  Assessing your risk level and forming a plan for your animals, your family and yourself ahead of time is key.  There are many fantastic websites such as www.sshc.org/evac/disaster.htmand www.ready.govwhich will help you start.  We face some unique challenges when evacuating our horses.  If you decide to evacuate it must be done early since your horse trailer will become difficult to drive once winds get above 35-40 mph.  It will also be necessary to leave someone to take care of the horses while evacuated and transport all feed and hay needed.  It may be an option to “locally” evacuate your horses to a more secure location.  Checking with local horses show facilities (like Canterbury), neighbors and friends may provide a safe alternative. Many of us have more horses than trailer space so decisions will have to be made about which horses get evacuated and which ones stay home.  These decisions are always easier to make before the hurricane is headed straight for us!

To the surprise of many, the safest place for your horse is in a large, well fenced pasture.  What fencing was best was also surprising.  As it turns out, mesh fences such as no-climb worked best.  Mesh fencing acted as a net to grab debris and wrap it up.  The fence also withstood very strong winds and was still effective at containing livestock.  Board fencing and barbed wire caused the most damage.  Flying debris broke boards, which became flying debris themselves, allowing livestock to escape.   Barbed wire caused numerous horrific lacerations, causing horses to be euthanized.  By giving horses a large fenced area they were able to move around to the safest location and weather the storm there.  Another important tip when setting up your property: ensure pastures are set up to keep horses away from power lines if they come down.

Horses that were found following Hurricane Andrew had to be reunited with their owners.  The importance of animal identification was further highlighted by Hurricane Katrina.  Microchips proved to be the most definitive way to prove identity but only up close.  Rescue personnel found large phone numbers written in grease pen to be the most helpful.  Your phone number on your horse allowed them to identify readily that the horse was owned, who the owner was and the address of the owner.  If area phones were working, rescue workers could then contact the owners.  Because area phones are often down, it is recommended to put a second phone number on your horse of someone who lives out of the area.  There are several ways to get all this information on your horse.  One way is to write everything in permanent fabric marker on a strip of sheet.  Braid this in to your horse’s mane and/or tail.  This can also be done with dog tags.  Writing down all your information on a piece of paper, placing it in a Ziploc bag and duct tapping it to your horse’s halter is another way to keep critical information on your horse.

A few quick things were identified that proved helpful post-disaster:

– Install a hand pump on your well. 

–  As you landscape your property, use native plants. Native plants are used to native weather and are less likely to be uprooted.

–  Get mobile home tie downs to secure vehicles and trailers – in the middle of the largest open area away from trees and buildings.

–  Have a disaster supply kit that includes: flashlight, battery operated radio, extra batteries,  fire  extinguishers, chlorine bleach, blankets, clothing, ready to eat food, first aid supplies, water,  prescription medicines, eyeglasses and cash. Update and check equipment at the beginning of each hurricane season.

–  Have on hand a box packed with halters, leads, duct tape, tarps and plastic, fly spray and animal medical supplies including bandages and medicines. Store in water proof container and secure

–  A two week supply of animal feed and medications should be brought in to the house and
stored in water proof containers

– Photograph or video property and animals, and take film/tape with you if you must evacuate.

Don’t forget – the most important thing you can do to be prepared for disasters:  Attend the Third Annual Springhill Equine Open House this Saturday October 8^th from 10am to 1pm.  We will have information on a wide variety of disasters and Connie Brooks, an internationally recognized Disasters and Animals response specialist.