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Lyme Disease in Horses

Used to be when I had an itch somewhere, I would scratch and forget it. Now I always check my itchy spots because I know I might see a tick. I am astounded by the number of ticks this year. They are on me, my dog Brook, and on the horses we see every day. When my wife Bonnie comes in from her gardening, she always transports a few into the house. They tell me the invasion is because of our recent mild winter. Whatever the cause, there are more of them. Lots more of them.

By far, most ticks are just an annoyance. The common dog and wood ticks are larger than the Ixodes or Deer tick. It’s this smaller tick that carries the bacteria which is the actual cause of Lymes. This tick lives about 2 years, and goes through life stages. Each stage requires a blood meal. In the early stages the blood meals come from small mice. In the change from nymph to adult, the blood meal is from large mammals which include the horse and you and me. As the ticks draw blood for their needs, the bacteria they carry goes into the host. The deer tick has to be on a horse (or person) for 24 hours in order for the bacteria it carries to be passed on.

Common symptoms in horses are a lameness that may jump from leg to leg, extreme skin sensitivity, and personality changes. Sometimes it is the easy going horse who becomes crabby.

A couple of years ago one of our clients told me that she has never had ticks on her place, When I asked why, she just pointed to her several free range hens that were in the yard, heads down pecking in the dirt. Ticks are a real treat for poultry. I now often suggest a few hens on farms where tick numbers are high. That wouldn’t be much help when you leave the farm on a trail ride, but it’s a good idea to check your horses for ticks after a ride through the woods anyway. Don’t miss the tail. Ticks seem drawn to horse tails.

Our ability to treat Lymes is actually better than our ability to diagnose it. Antibiotics for a few to several weeks are effective if done early on. There is a good blood test for the disease. It is relatively expensive, and it often takes a week to get results back from the lab. We are now using the “snap test” that gives us an answer right at the side of the horse in about 10 minutes for 1/3 the price.


-David A. Jefferson, DVM

Comments (4)

  1. Do we treat once we determine the horse has Lime? My horse has no symptoms but has tested positive at almost 400 and now the next test is being done (some kind of block I think).

    • In our area of the state of Maine, probably 50% of horses will test positive, which does not necessarily meant that they are sick with the disease. It just means that they have been exposed. I (and probably you) carry antibodies for Measles, which doesn’t mean we are sick. We have been exposed, and now carry antibodies in our blood. In our practice we do not take blood for a Lymes test unless we have a horse with symptoms for Lymes. If they have symptoms, and a high titer, we treat them.

  2. I am in the same boat as Kathleen. Two questions I’m struggling with and hoping you may by able to advise:

    In the case of a very high titer and no symptoms:

    – Is there the possibility that symptoms may never occur?

    – If I don’t treat it now, but wait until I see symptoms, is there a risk of the disease progressing more rapidly because I delayed treatment?

    I live in VA. My guy was just diagnosed and my vet is suggesting to proceed with the IV treatment. I’m doing as much research as possible before i make a decision.

    Thanks very much for your sharing your expertise.


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