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Lyme disease may not be the most prevalent threat to your horse, but it can definitely impact their health. Lameness, arthritis, neurological disorders, dermatitis and moon blindness are the most common symptoms. Lyme Disease was first recognized as a disease in 1975, when 51 patients in Connecticut were diagnosed with oligoarthritis. The Tick Encounter Research Center in Rhode Island is a Nonprofit Section of the Department of Biological Sciences at Rhode Island University. Its entire  focus is on Tick-borne diseases, but especially Lyme Disease. The CDC reported that 81% of all arthropod related disease cases are Lyme Disease In 1985 researchers finally were able to determine  what caused Lyme Disease, it was a spirochete found in the gut of a tick. A spirochete is a slender  spirally strand of bacteria. The most common transmission of Lyme Disease is by a female black  legged tick found on whitetail deer.  

Most of us don’t realize that ticks are a three host vector, which means each stage requires a  vertebrate blood meal. The three stages are larvae, nymph, and adult. Northeastern and Midwestern  states have the greatest prevalence of black legged ticks. They mate in the Fall and early spring, it takes almost two years for a tick to complete a life cycle. Spirochete are transmitted to the host in the  ticks saliva when they are feeding. One female produces 3000 eggs, when they hatch the nymphs are  the size of a grain of sand, so they are very hard to detect. Adult ticks are the most active from Fall to  Spring when the temperature is at least 40°F. The infected tick must be attached for at least 24 hours  for there to be spirochete transmission. Estimates now show that at least 50% of adult ticks are  infected.  

Lyme Disease is difficult to diagnose in humans and in animals because its symptoms are very similar  to the symptoms of many other diseases. Fever, muscle pain, and joint discomfort make one suspect a  viral infection, arthritis or even Multiple Sclerosis, but the red bullseye dermatitis around the tick bite  is a major indicator it may be Lyme Disease. In the south and Pacific Northwest cold blooded lizard  which are reptiles frequently are the hosts for nymphs. We see them so commonly we don’t think  about them helping to spread ticks around the yard or barns. If you live in the Northeast or Midwest  you and your horse have a 25 times higher chance of contracting Lyme Disease. Diagnosing Lyme  Disease can be very difficult as the symptoms are similar to other diseases and some horses are  asymptomatic. The most common symptoms are head tilt, difficulty swallowing, tail paralysis,  warm, swollen painful forelimb joints, and aimless wondering.  

You might wonder how a blind tick can possibly cause so much havoc? How do ticks find their hosts?  They detect exhaled carbon dioxide and ammonia, as well as sensing vibrations, moisture, and body  heat. Ticks can’t jump like fleas so they do questing which means they hang on to tall grass so when  an unsuspecting animal walks by they grab hold and find their blood meal. There is no specific blood  

test for Lyme Disease, and there is no vaccine for it as of yet. Your best bet is to prevent your horse  from being exposed to it.  

  1. Keep your pastures mowed, and keep an area mowed between wooded areas and your  turnout areas.  
     
  2. Clear brush and weeds from your pastures.  
     
  3. Fence off wooded areas from your paddocks. 
     
  4. Use spot on tick prevention.  
     
  5. Grooming your horse needs to include checking for ticks in warm moist areas, and where the  tail or manes may have made contact with the ground or trees. 

If your horse gets Lyme Disease your vet will recommend a course of tetracycline and ampicillin  usually for at least four weeks. Anti-rheumatoid arthritis and anti-inflammatory medications may also  be used based upon your horses symptoms and your vet’s plan of care. You need to understand that  even with this treatment plan, clinical symptoms can still persist. I hope that this article has been  informative and useful in caring for the horses in your care.

Dr. Dana Price
Published on 2021-04-19