Ticks are becoming an increasingly significant parasite of horses
Written by: Thomas Lenz, DVM., M.S., DACT
Ticks are becoming an increasingly significant parasite of horses across the United States. In many areas of the country where they have not occurred before, they are now commonplace. Some blame it on global warming while others believe the increase in deer and other wildlife populations, that also suffer from tick infestation, has resulted in ticks becoming more prevalent, which has resulted in more ticks on our horses. Regardless of the reason, ticks are a major problem. Ticks cause local skin and tissue irritation which can result in the horse constantly rubbing on trees or fences resulting in hair loss; hair coat damage; anemia due to blood loss and transmit a number of serious diseases including Equine Piroplasmosis, Lyme Disease, Equine Granulocytic Anaplasmosis (Ehrlichiosis) and Tick Paralysis. Ticks are not species-specific so the same ticks that feed on your horse can also feed on your dog or you.
Ticks are blind and find their hosts by detecting ammonia which is given off by a horse's breath and body during sweating or by sensing heat, moisture, and vibrations. They wait for a host while resting on the tips of grasses and shrubs with their first pair of legs outstretched. When the horse brushes by, the tick quickly climbs aboard. Some ticks attach immediately while others move around the horse's body, looking for areas where the skin is thinner. That's why ticks are most often found on a horse's chest, underbelly, mane, tail, or inside their flank. The result is often a local skin reaction that appears as a small, firm nodule. Once filled with blood, ticks drop off to molt and progress to the next stage of their life cycle or in the case of adult females, lay eggs.
Because ticks infected with serious diseases do not usually transmit those pathogens immediately and often must feed for a period of time before disease transmission, removing them from your horse as soon as possible is important. Check your horses for ticks thoroughly after a ride and at least daily if they're out on pasture in order to prevent disease transmission.
Often it is easier to feel ticks than see them. Scratch the horse's skin in areas where ticks like to attach with your fingertips for small bumps that may indicate smaller immature ticks that are difficult to see. Should you find a tick on your horse, remove it immediately. However, forget all the rumors you've heard about tick removal as they usually cause more damage than benefit. Do not crush or twist the tick as it causes them to regurgitate blood back into your horses which increases the chance of infection or disease transmission. Do not apply baby oil or petroleum in an attempt to smother then or force the tick to detach with a lit match. Those methods do not work and can cause damage to your horse. Instead, apply gloves and use tweezers to gently remove the tick. Grasp the tick firmly by the head where it enters the horse's skin. Don't squeeze or yank! Instead, pull firmly, slowly and steadily straight away from the skin until the tick's head comes free. Drop detached ticks in a small jar of rubbing alcohol in order to kill it. Wash the attachment site with a mild antiseptic and then wash your hands.
From a pasture management perspective, you can decrease the number of ticks your horse may pick up by removing brush and mowing tall grass where ticks like to live and discouraging wildlife such as deer that tend to reintroduce ticks to grazing areas. Guinea fowl or free-range chickens do an excellent job of finding and eating ticks around the barnyard.
Tick prevention requires diligence to locate them on your horse and remove them, application of tick specific topical acaricides applied directly on the horse and environmental controls. Coumaphos spray or powder; pyrethrins; synthetic pyrethroids applied as a wipe, spray, or spot-on; and zetacypermethrin dusting powders are the most commonly used repellents. Brand names include Co-Ral, Deep Woods Off, and Frontline spray, which should be applied to the horse's main, tail head, chest, and underbelly. You don't really need to spray the entire horse. Whichever product you choose to use, the labels should be checked to make sure they are effective against ticks as many insect repellents are not. Apply repellants before riding or turning your horses out on pasture. Alternatively, orally administered ivermectin or moxidectin dewormers are effective against ticks on horses, however, the tick must take a blood meal from the treated horse in order for the drug to be effective. It should be noted that Amitraz should NOT be used on horses as it can cause toxic effects.
Pyrethrin, Permethrin, Cypermethrin, and commercial grade pyrethroids can be applied to pastures and paddocks to destroy ticks in the environment but label directions should be closely followed or a professional pest control specialist hired to apply them. When using pesticides of any type it is important to carefully read the label as the product may be contraindicated in some horses. Especially foals under the age of three months.
If you have questions on tick control or the diseases they can transmit to your horses, talk to your local equine veterinarian.
Article provided courtesy of AAEP Alliance Partner, AQHA.
Article reviewed and updated by original author in 2020.
About the author: Thomas R. Lenz, DVM, M.S., Dip/ornate of the American College of Theriogenologists, is a trustee of the American Horse Council, past chairman of AQHA research committee and past president of the American Association of Equine Practitioners.