Is Something Afoul with Your Foal?
By Dr. Frederick Harper, University of Tennessee
Your mare is about to present you with a beautiful new foal. Worms are probably the last thing on your mind, but they can be critical to your foal's early development and overall health as it matures. Here are some simple worming tips to get your foal off to a healthy, worm-free start.
"It's vital to use a deworming product that is safe and effective for pregnant mares and foals," says Thomas Bello, D.V.M., Ph.D. Dr. Bello recommends these three steps to ensure parasite control: Make sure your mare is on a regular deworming program; Thoroughly clean the foaling stall and the mare's udder just before the foal is due, and keep them as clean as possible until the foal is weaned. (This will keep the foal's environment as parasite-free as possible because the mare is the primary source of parasite infection.); Put the foal on a regular deworming schedule.
some horse owners believe that deworming during pregnancy is unsafe for the mare. This is not true. It is important to have mares on a regular deworming routine, and many veterinarians recommend deworming mares prior to foaling day because, starting four or five days after delivery, worms often pass through the mare's milk to the foal. Ask your veterinarian about dewormers that are both safe and effective for pregnant mares be sure to use one that is specifically recommended during pregnancy. One medication approved for use on both pregnant and lactating mares is ivermectin (i.e, Zimecterin or Eqvalan).
Unlike human babies, foals don't receive protective antibodies from their mothers during gestation. Thus, at birth, foals are prey to the many parasites present in the bedding, on contaminated ground, or on soil surfaces. In order to ensure the newcomer's protection from parasites after birth, you should establish a deworming program for your foal immediately. Many veterinarians recommend beginning a foal deworming program at one month old with ivermectin.
Foals are exposed continuously to parasite infection, particularly from ascarid (roundworm) eggs because, no matter how clean the stables are kept, ascarid eggs abound. These sticky, practically indestructible, ascarid eggs can survive for years on buckets, walls, bedding, pastures and even on the mare's udder. All foals eat fresh manure every few hours in order to "seed" their digestive tract with beneficial microorganisms essential for proper digestion of vegetable matter. As a result, any infective ascarid eggs present in the manure can find their way into the youngster's system where the ascarid larvae hatches out, burrows into the intestinal tract and begins its damage.
From birth through the first two years, young horses have an especially low resistance to parasites and can quickly acquire massive worm burdens. However, damage inflicted by these worms is gradual and subtle, so you may not notice any signs of illness at the onset. Meanwhile, your prized foal's growth and development become impaired, its performance ability reduced, and its resistance to disease lowered - problems that have long-term consequences.
A carefully-planned and strictly-followed deworming schedule is the only way to protect your foal from parasite damage. Be sure to read product labels carefully and avoid using drugs not approved for use in foals, because some can be highly toxic. If the label indications are confusing, ask your veterinarian for advice.
Deworming dosage is determined by the foal's weight, so you should weight your foal each time a deworming is scheduled. Inexpensive height-weight tapes can be purchased to help estimate weight accurately if you don't have access to a scale. It's important not to overlook any changes in weight, because underdosing can be as ineffective as not worming at all, and overdosing can cause uncomfortable side effects (for example, toxicity).
A rigorous deworming program will not only keep parasite damage to a minimum, but can also ensure your foal's maturation into a beautiful, healthy horse
Canadian Horseman May/June 1999