Ubiquitous news reports of Lyme disease and its affects on humans warn of dire consequences for those who ignore the bite of an insect the size of a pencil tip. Dr. Bonnie Barr, VMD, DACVIM, of Rood & Riddle Equine Hospital, says the tiny insect can also have a weighty effect on our 1,000-pound equine friends.
In a Veterinary Answers Q&A with OffTrackThorouhgbreds.com, Dr. Barr offers her perspective on the disease, providing tips for prevention, and suggestions on where to look for a tick that may be nestled into a horse’s hair.
The 1997 graduate of the University of Pennsylvania, who received her Diplomate American College of Veterinary Internal Medicine in 2003, says that while it is not known whether there is an uptick in the number of cases of Lyme in horses, or simply more accurate testing, Lyme disease is a disease that should be considered when an equine shows vague signs and symptoms of the illness.
Q: Lyme disease stories have been all over the news, as occurrences in humans reportedly soars. Is there evidence that more horses are testing positive for the disease as well? Does it appear that Lyme disease is on the rise in horses, and if so, what could be causing the uptick?
I am not sure if more horses are testing positive for Lyme disease or if the disease is on the rise in horses. Recent improvements in diagnostic testing for Lyme disease has enabled veterinarians to better define the infection status of the horse, specifically if early or chronically infected. The test also distinguishes between an antibody increase due to infection and vaccination.
The test is called Lyme Disease Multiplex Testing for horses and it is performed at Cornell University.
Q: Which circumstances put a horse more at risk for contracting the disease? For example, are horses who graze in tall grass more prone than those with mowed paddocks?
Risks include: tall grass, areas with a lot of leaf or brush piled in yards, paddocks or on the farm, pastures boarded by brush thickets or forests
Q: What preventative tools are available to owners, and is there a vaccine? And how effective are these tools?
Preventative tools: 1. Minimize the tick population-keeping the fence lines mowed, grass trimmed short around barns/arenas, move horses to pastures not boarded by bushy areas or forests
2. Check horses for ticks daily-pay particular attention to the base of mane, neck, under the tail and in the ears
3. Apply insect repellant or wipes that contain Permethrin or Pyrethrin
4. Monitor for any vague symptoms-lethargy, depression, low-grade fever
5. Remove any tick seen within 24 hours
Currently there is no commercially approved vaccine for horses. Some have used the commercially available vaccine for dogs.
Q: If an owner pulls a tick off a horse, should the site be monitored, and if so, what types of reactions to the skin should the owner look for?
Due to the type of hair coat a horse has, the characteristic bulls-eye-type lesions might not be seen. There is a possibility of a reaction in areas of less hair coverage, so a rash with a bulls-eye or raised appearance may be noted.
Q: Even if no tick is present, are there telltale signs that an owner can spot, which indicate the presence of the disease?
The clinical signs are vague and similar to other disorders. Some symptoms are lethargy, low-grade fever, sporadic lameness, shifting leg lameness, weight loss, altered mentation, swollen joints, neck/back pain, changes in behavior and neurologic signs.
Q: Once a veterinarian confirms the disease, what course of treatment is used to cure it, and what is the duration of treatment?
Treatment is antibiotics, specifically tetracyclines. These include Oxytetracycline, Doxycycline, and Minocycline. Usually, a treatment course is 30 to 45 days.
Q: Lyme disease in people can have a profound impact on health. Is it the same in horses?
Lyme disease can be debilitating and chronic. Long-term complications can include damage to joints, skin, nervous system or even vision.