The headline on the first page of the March 30, 2014 Lewiston Maine Sun Journal shouted “TICKED OFF”. What followed was a full 3 page article about Lyme disease in people. I knew that we had a severe problem here in New England, but was unaware that New Hampshire has the highest rate of Lyme disease in the US, with Maine coming in second. It is not a reportable disease in horses, so we don’t have numbers, but every equine veterinarian in New England sees more cases every year. There is never a moment in our practice when we are not treating at least one horse with Lyme disease. There are times in the warmer months when we will be treating a number at any given time. In the winter the ticks do just fine as long as there is snow cover, and become active again once the temperature hits 40 degrees. I know veterinarians out west who have never seen a horse with the problem. In the same way, I’ve never seen a horse with a rattlesnake bite. Ticks thrive in woodlands and bushy fields, rattlesnakes like the desert.
I wrote an article about Lyme disease 3 years ago for the Horse’s Maine. It was a brief summary of what we know about the problem in horses. The article was factual: what causes the disease, its prevention, and treatment. Since that time I have seen many more cases, and thought it might be helpful to share my own experience and thoughts about Lyme disease in horses that I have seen in Maine. I want to be clear that these are my opinions about Lyme and may not be shared by other equine veterinarians.
I have noticed that there are certain towns in Maine that consistently have a high incidence of Lyme in horses (and probably in people). One such town is just south of Portland. Perhaps the high rate of infection is due to the local restrictions on deer hunting. In any area where the deer population is high, Lyme will be more common because deer are one of the hosts for part of the life cycle of the ticks that carry the disease. In towns like these I always include Lyme disease in my differential diagnosis for almost any equine problem. There are also towns in Maine where I have never seen a case.
Looking for ticks when your horses come in? You’ll have to look carefully. The nymph stage of the ticks that carry the bacteria that cause the disease are tiny, about the size of the tip of a pencil. We find most underneath the lower jaw, at the tail head, on the underside of the tail, and beneath the mane. Ticks like dark places. As you have probably heard, they have to be on a horse (or you and I) at least 24 hours for the bacteria to pass from the tick to the host.
The most common symptom of Lyme disease that I see is extreme skin sensitivity. Even horses that normally love to be brushed and fussed over just don’t want to be touched. Many articles will talk about a shifting lameness (in this leg today, in that leg tomorrow) as a common symptom of Lymes. I haven’t noticed that so much. I do see Lyme horses that move stiffly as though they are sore all over. There can be a variety of other symptoms, depending where in the body the bacteria that causes Lymes takes up residence. Our practice has seen Lyme horses with neurologic problems, vision issues, and GI symptoms among other things. When vets see a horse that is showing many of the common symptoms, we refer to them as being “Lymie”.
Last year an older gelding in Oxford County kept losing weight. I did the usual dentistry and ran all the normal blood tests and fecals, but everything came up normal. I couldn’t figure out what was wrong and chalked it up to old age. I didn’t suspect Lymes, but to humor his owner I took a Lymes test, and when he tested very positive, we put him on the usual antibiotic, and he promptly gained all his weight back. The next horse we saw with the same perplexing symptoms a year later turned out to have Lyme disease as well, and also responded with treatment, gaining 60 pounds back quickly.
Most veterinarians in New England will send their blood samples for Lymes testing to either the University of Connecticut or to Cornell. These are different tests. Both are valid, and each has its fans. There is also a “snap” test, the same one that your dog gets with his annual physical. We run that identical test on horses, right in the barn, and get a yes or no answer within 10 minutes. It doesn’t give numbers, but if a horse seems “Lymie” we sometimes use it so that we can begin treatment right away.
The antibiotic Doxycycline is the usual treatment for Lymes in people and in horses. The pills have become prohibitively expensive; so many veterinarians are using compounding pharmacies to make the powder. Some veterinarians believe that IV treatment is much more effective than oral, and one limited research paper from years ago did show that. I personally have not found that to be the case. I treat with oral Doxycyline for 6 weeks. My recommendation is that horses being treated this length of time be on a probiotic. If an animal is still not right after that long antibiotic treatment, I often recommend an herbal mix that a local certified herbalist puts together.
There are numerous articles and even books about people with Lymes who don’t test positive on the lab tests. There are also many people for whom the antibiotic is not effective. You probably know at least one person with Lyme disease who can’t shake it and is living a life of misery. I think that the blood tests and our treatment for the problem in horses are usually effective because we are testing and treating earlier in the course of the disease. When an owner has an animal that isn’t right they look for help quickly, whereas when we ourselves are feeling off, we tend to dismiss our symptoms thinking it’s because we are overtired or stressed. Some MD’s are skeptical of Lymes and as a result diagnostics and treatment may be put off for months or years. When the organism is in the body for a long time, it can hide in joints and seems to be able to mutate and become resistant to the usual treatments. Chronic Lymes is very debilitating. Again, I think the success in diagnosis and treatment of horses is because we know there is such a thing as Lymes and we get at it quickly.
An interesting side note to Lymes is the disease that we are now calling Anaplasmosis. It is carried by ticks as well, and it is often characterized by a persistent fever and legs that stock up. These horses often look neurologic. Labs usually test for this along with Lymes and it is included in the snap test. Treatment is the same as for Lymes.
I am not a believer in testing all horses in a barn for this disease. Many horses (probably most in Maine and New Hampshire) have been exposed and are carrying antibodies that will show in a blood test. It is just like you or I who are most likely carrying antibodies for measles, which might only mean that we have been exposed and have immunity against it. I think it is important to test for horses that are showing symptoms but consider it a waste of money and time to test non symptomatic horses. This is one of many aspects of Lyme disease that are controversial, and as I mentioned, these are my personal opinions and may prove to be wrong.
Lyme disease has only been recognized in New England for about 40 years but it looks like it’s here to stay, and we’ll just have to learn from each other how to best live and deal with it.