PROTECTING FOALS FROM INTERNAL PARASITES
A Guide for Horse Owners

There's a lot of hype and misinformation floating around about the best ways to keep your horse healthy - it can be tough sometimes to know what to believe. A good deworming program is essential to any horse's health, but is especially important to young foals. Foals are particularly at risk for internal parasite infestation, and the infection and disease parasites can cause.

Where do you begin when planning a deworming program for your foal? The FDA requires all brands to be labeled with valuable information to help you be a good consumer, so that's a good place to start. Keep in mind that not all products are labeled for use on foals. For instance, ivermectin products are labeled for use on foals at 7 days of age to help prevent "foal-heat diarrhea," which can be caused by Strongyloides westeri (intestinal threadworms). Ascarids, or roundworms, also can cause problems for foals. QUEST® (moxidectin) is restricted for use in foals 4 months of age or older.

Key items to consider:

Intestinal Threadworms (Strongyloides westeri)

• Threadworms are long and hair-like, growing to about 2/5 inch as adults.
• Horses are infected by eating infective larvae or by penetration through the skin.
• Young foals also can be exposed to the worm by nursing from their infected mothers.
• Untreated foals can see the worst damage from this parasite - diarrhea, weight loss and failure to thrive and grow at a normal rate.
• Diarrhea in foals aged 7-10 days may be caused by intestinal threadworms.
• A dewormer like Farnam's HORSE HEALTH Equine Ivermectin may be recommended by your vet from early in your foal's life and as often as every month until weaning. This dewormer also is safe to use in pregnant and nursing mares.
• Be very careful to read your dewormer label, since most paste dewormers are not approved to control Strongyloides westeri, and some products cannot be used on foals this young.
• If in doubt, be sure to check with your veterinarian.
  

Ascarids or Roundworms (Parascaris Equorum)

• Adult ascarids can reach up to about 20 inches long, and are especially dangerous in foals aged 6 months or younger.
• If a young foal swallows infected grasses as he grazes in the pasture, severe infection can build up quickly and lead to liver and lung damage, poor overall growth and even death.
• As ascarid larvae move through the blood system, foals can experience coughing, fever, pneumonia, bleeding lungs and other respiratory infections.
• Adult roundworms live in the small intestine where they can cause colic, blockage, ruptured gut and death.
• Look for these symptoms in foals -
  • Alternating bouts of foul-smelling diarrhea and constipation
  • Weight loss that may be hidden by a potbellied appearance
  • Low energy
• Many paste dewormer compounds kill adult ascarids, but only dewormers like Farnam's Horse Health (ivermectin) kill third and fourth stage P. equorum larvae.
• Daily deworming pellets like Farnam's CONTINUEX® (pyrantel tartrate) can provide continuous protection against adult roundworms and fourth stage P. equorum larvae, and can be used in foals when they are able to feed on grain.
  

Warnings and Cautions
When deworming foals, it's vital to read the label instructions. Like any other drug or controlled substance, equine dewormers should be respected as serious medicine. When you follow label instructions, dewormers are generally very safe and effective. But the cautions and warnings on the label, if ignored, can lead to reduced effectiveness, injury or even death.

Be certain to check the label for any restrictions on approved use in foals. QUEST® (moxidectin), for example, is restricted for use in foals 4 months of age or older.

Environmental Control

The University of Illinois College of Veterinary Medicine recommends that environmental control will aid your deworming program in controlling parasites:

• Remove feces routinely to decrease transmission of eggs and larvae. Do not dispose of feces onto pastures or near feed and water supply.
• Harrow pastures to break up fecal pats and kill larvae only in hot, dry weather or below freezing weather.
• Quarantine all new additions to your herd and have your veterinarian perform fecal examinations. Deworm with appropriate anthelmintics if indicated.
• Deworm all horses at the same time.

Evaluate parasite control via fecal examination of 10 percent of horses two or three times per year, 14 days after deworming.

Dr. Doug Hutchens, veterinary parasitologist at the University of Illinois College of Veterinary Medicine in Urbana, explains that if environmental control is adequate, "less than 10 percent of samples obtained should contain eggs." If samples show significant egg counts, reevaluate drugs and method of administration.

"Most do-it-yourself programs break down when the wrong drug is used or the drug is improperly administered because the dose is too small or the horse spits it out," says Dr. R. Dean Scoggins, Equine Extension veterinarian at the college.

For more information on label claims and equine parasites, check out www.fda.gov or manufacturer's Web sites like www.intervet.com or www.farnamhorse.com or talk with your equine veterinarian.

®CONTINUEX is a registered trademark of Farnam Companies, Inc.
®QUEST is a registered trademark of American Cyanamid Company.