Tuesday, March 30, 2010

A Legend

It is with great sadness that I report to you that Dr. Harold “Red” Sheridan passed away yesterday afternoon. Many of you may not know him or may not have had the opportunity to meet him. You need to know that he had a tremendous impact on not only me but also our practice, his clients, his community and the veterinary profession. It is not my goal to write a eulogy here. Other people in other places will do a much better job than what I could ever attempt. He was one of the founding members of what is now West Michigan Veterinary Service. The leadership and path he blazed has made our practice what it is today. He was a very talented mixed animal veterinarian. He was a true ‘James Herriot’ of veterinary practice. Over his career he had the opportunity to do and see so many things. There was more experience there than what he could fully share. He was a constant source of wisdom and insight. He will be greatly missed by his WMVS family. There are more details at: www.throopfh.com/obituary.php?Obituary_ID=47 or obits.mlive.com/obituaries/grandrapids/obituary.aspx?n=harold-sheridan-red&pid=141349402

Tuesday, March 23, 2010

COW (Case of the Week): Strangles!

Last week we encountered our first strangles outbreak of the year. As you probably already know, Strangles is highly contagious upper airway infection. Horses rarely die from this disease, though on rare occasion it can be deadly. They do, however, get very sick from it. Typically affected horses have very large lymph nodes under their jaw that get so large they can ‘strangle’ their upper airway—thus the name. After a couple of days, the lymph nodes will break open and drain.

The disease is caused by a bacteria named Strep. equi ssp. equi. This bug is easily spread from one horse to another, usually through nose to nose contact or by sharing water buckets or a common water tank. It is possible for people to carry this bug around on them and transmit it from an infected horse to another horse. Because of the highly contagious nature of this disease, quarantining affected individuals and good hygiene practices are necessary to limit its spread. Horses can continue to shed the bacteria (and thus infect other horses) for up to 6 months after they have recovered. The only way to tell for sure if they are still shedding the bacterial is to get a swab of the back to the throat and send it into a lab.

Immunity to this disease is not life long, even after a clinical infection. Affected horses usually have immunity for 18-24 months. There are several different vaccines available for this disease. The one we are currently recommending is an intra-muscular injection. There is also an intra-nasal vaccine available. Great care must be exercised when handling and administering the intra-nasal product. Protective immunity from the vaccines are probably 6-12 months, at best.

The best way to prevent the disease is to quarantine new horses coming into the barn. A two week quarantine period is usually sufficient. During the quarantine period, the horse should be kept away from direct contact with other horses and not have access to a common water source or share water buckets with other horses. Also, the quarantined horse should be handled and fed, after all the other horses are first tended to.

Aside from quarantining, or preventing exposure, vaccination is the best tool we have to prevent this disease. We recommend strangles vaccination if you take your horse to barns or shows where they are stabled with other horses of unknown background or if there is a lot of traffic of new horses through the barn. When you go to shows or other organized horse events, do not let your horse share water buckets or hay bags with other horses.

Saturday, March 13, 2010

COW (case of the week): Alsike Clover

This week's COW is another feed related toxicity. It seems I have had a run of these lately. This time the offending agent was Alsike Clover. Here is a good picture of what this plant looks like. It can cause the skin to be hyper-sensitive to sunlight. We refer to that as photosensitivity. Photosensitivity causes the skin (almost always only the white skin) to sunburn extremely easily. For this reason we do not usually see these cases in the winter. However, when a horse gets exposed to a significant amount (usually more than 20%) of this in their hay and you get a good run of sunny weather like we’ve had for the past couple of weeks, then you can see these skin conditions. No one knows exactly what it is in Alsike clover that causes this syndrome, but we do know that it affects the liver, primarily the bile ducts, and the photosensitivity is the result of the effects on the liver.

The skin irritation with these cases can become quite extensive. As I mentioned earlier, it almost always just affects the white skin. Sunburn classically affects the muzzle- as it did in the case I saw this week. It also almost always affects the lower legs and at first glance looks a lot like ‘scratches’ of the lower limbs. Again, this usually only affects the white skinned areas. This presentation of lower leg dermatitis can make it a little difficult to sort out from regular ‘scratches.’ If there is any doubt, we can take some samples from the affected areas and look at it under a microscope. The other hint is that when you clip the skin, you will see evidence of diffuse skin irritation that goes beyond just the crusty areas you first noticed before clipping.

There is no specific blood test for Alsike clover toxicity, but we will often see elevations in liver enzymes. Treatment is fairly straight forward: remove the offending agent from the diet and treat the skin. So get a good look at this picture and check your hay or your pastures (once things start to grow again in the spring). If this stuff makes up more than 20% of the hay, find an alternate hay source.

Friday, March 12, 2010

Interesting Article

The April issue of Horse Illustrated has a nice summary article on dealing with parasite resistance. I can't find a web link to it, but if you get this magazine, it's worth looking at. It really puts an exclamation point on our new deworming protocol recomendations. See the February 20, post on this blog.

Spring is Coming!

10 signs Spring is coming (in no particular order):

3.The manure pile stinks again
4.You don’t have to break ice out of the water buckets when feeding
5.Foals are being born.
6.You here birds when you feed the horses in the morning.
7.You don’t have to fight the snow and ice ruts in the driveway when you take the trash to the road.
8.There is some daylight when you feed in the morning, AND some when you feed at night.
9.Your ‘to do list’ is longer then your ‘have time to do list’
10.After brushing your horse, you have more horse hair then your horse does.

Thursday, March 11, 2010


A case of Rabies in a horse in Michigan was recently reported. The horse was from Lapeer county (thumb area of Michigan). The horse first started showing symptoms on Feb. 28, and was euthanized 2 days later. Four individuals are now undergoing post-exposure treatment. It is not know how the horse became infected, though both bat and skunk rabies have been detected previously in that county.

This case highlights how real the threat of Rabies is. Any threat of Rabies needs to be take very seriously not only because the infected individual always dies (there is no treatment), but also because it is highly contagious across species. A horse may contract Rabies from a bat and the horse could then subsequently expose humans. This makes Rabies not just an animal health issue. It has immense implications to public health. That is why your dog has to have a current Rabies vaccine to be licensed. Rabies vaccination of horses is not yet required by law. Just because the law does not require it does not mean it is not necessary. The reality is that Rabies vaccines are some of the cheapest and most effective vaccines we have. Given that the disease is always fatal and can be spread to humans, I think it is crazy to not have your horses properly immunized against this devastating disease. This is especially true if your horse has potential exposure to wildlife or bats and/or has exposure to people. What horse in Michigan doesn’t?

Buying meds online?

Check out this video from USA Today. This short clip expounds on some of the pitfalls with on-line sales. It really is small animal oriented, but the same concepts apply to horses.


Friday, March 5, 2010

COW (case of the week): Monensin Toxicity

One of the more sad cases I encountered this week was a horse that was exposed to monensin. If you haven’t yet heard, MONENSIN IS TOXIC TO HORSES! Monensin is an ionophore that is commonly added to cattle and poultry feeds. It enhances the feed efficiency of feeds. This stuff has been being added to cattle feeds for a long time. The fact that is highly toxic to horses is nothing new either. But apparently there are people who have not yet heard.

Fortunately we don’t often see monensin toxicity since it is generally known that horses should never get this stuff. However, apparently not everyone is aware how sensitive horses are to ionophores. In the case I saw this week, the owner had no idea about the toxicity of monensin. What makes these cases so sad is just how much affected horse’s suffer and how easily preventable it is. Symptoms vary based on how much the horse consumes. Symptoms are progressive and typically include abdominal pain, anorexia, sweating, unsteadiness on their feet, stiff gait and/or a reluctance to move. Affected horses often just look like a severe colic. Often they will have a high heart rate and low blood pressure. If a horse survives, they will likely have permanent heart damage that can cause death, weeks or months after the initial exposure.

Unfortunately, there really is not specific a antidote for ionophore toxicity. If caught early enough, we can administer mineral oil or activated charcoal via a stomach tube to slow or inhibit the absorption. Otherwise treatment consists of supportive therapy. Vitamin E and selenium may be of some benefit.

The moral of the story is do not store any feed with an ionophore, like monensin or lasalocid, anywhere near horse feed. If you have any feeds made specifically for cattle or poultry check the labels to ensure they do not have these products added to them. To prevent accidental exposure, products containing ionophores should never be stored in the same location as horse feed or in any location where a horse may gain access to them. Spread the word to all of your cattle friends who may also have a horse.

Thursday, March 4, 2010

New CEM Surveillance Testing Program

If you are into breeding at all, you are probably well aware of the recent ‘outbreak’ of Contagious Equine Metritis (CEM). That outbreak has pretty well been brought under control, though the USDA is still completing follow up testing on some horses. CEM is a sexually transmitted disease of horses that causes infertility in mares. Carrier stallions do not typically show any symptoms. CEM had been eradicated from the United States since the late 1970’s. The most recent outbreak was first detected in December of 2008 in a stallion in Kentucky. The USDA quickly took action to find any other infected horses. That action set off a cascade of testing and trace backs that affected just about every state. We dealt with several exposed mares and a couple of exposed stallions here in West Michigan. Through very thorough testing (maybe even a little over board) by the USDA, with the help of private practitioners, this most recent outbreak has been fairly quickly extinguished.

As a result of that outbreak, the United States is no longer considered free of CEM. The USDA is in the process of trying to do some surveillance testing to hopefully return us to a CEM free state. As a part of that program, the USDA is offering free testing of eligible breeding stallions. The ‘free’ part pays for laboratory and shipping costs. It does not pay for veterinary fees to acquire the samples and do the submissions. However, if you have a breeding stallion and want to be able to advertise him as CEM free, this program could save you a significant amount of expense. Please feel free to contact our office if you are interested in having your breeding stallion tested, or you can check out http://www.aphis.usda.gov/animal_health/area_offices/