Keeping internal parasites under control is an ongoing part of looking after horses. Several different kinds of worms are commonly found in horses, and unless a horse is on a proper deworming program, they can cause serious internal damage before you realize what is happening to your horse. In the long run, a regular parasite control program will save you money in feed costs and veterinary bills. Deworming your horse is almost as important as supplying good quality food and water.

What are the most common worms found in horses in Alberta?

More than 150 internal parasites afflict horses. Among the most common are large strongyles, small strongyles, ascarids, pinworms, bots and tapeworms.

Any or all of these parasites can be present in a horse at one time. Different worms harm the horse in different ways. They can damage tissues and vital organs, cause obstructions and ulcerations within the digestive tract, and cause irritation as they lay eggs.

How can I tell if my horse has worms?

Contrary to popular belief, many horses that have dangerous parasite levels appear to be perfectly healthy. It's safe to assume your horse has worms. The only way to be sure about the degree of infestation is to have your veterinarian perform a fecal laboratory examination.

Some horses, particularly young ones, do show obvious signs of carrying a heavy worm load. Symptoms may include:

• dull rough
• haircoat
• lack of energy
• weight loss
• coughing and/or nasal discharge
• tail rubbing and hair loss
• colic
• summer sores
• loss of appetite
• loss of condition
• diarrhea

The best protection is to combine a deworming program with manure control. That way you kill the parasites already living in the horse and lessen the amount of reinfestation.

There are many safe, convenient products available today. Consult your veterinarian to set up the best program for your situation. A minimum deworming schedule is twice a year, but more frequent deworming is called for in many situations.

Deworming medication for horses comes in three formats. Most people today use paste dewormers which come already packaged in an easy-to-use oral syringe. You can buy them at most tack and feed stores. You can also buy dewormer as a feed additive. Veterinarians sometimes administer liquid dewormer by stomach tube.

Whatever type you use, it is important to follow directions and make sure the horse gets the whole dose. You can buy a weight tape to figure out how much your horse weighs. It's also important to worm all horses on the property at the same time.

There are six different drug classes of chemical dewormers, but many different brand names. Most experts recommend rotating among the classes to prevent the worms from developing a resistance. When choosing products, make sure you're going by the class of dewormer not the brand name. Your veterinarian can help you choose the best dewormers for different times of year.

Since parasites are primarily transferred through manure, picking up and disposing of droppings in paddocks and corrals at least twice a week will go a long way toward controlling worms. Mow and harrow pastures regularly to break up manure piles and expose parasite eggs and larvae to the elements.

Remove bot eggs from the horse's haircoat before he can lick them off. A safety razor works well or you can buy specialized bot remover.

Use a feeder for hay and grain rather than feeding off the ground.

If you can, rotate pastures with other animals. Allowing sheep or cattle to graze in rotation with horses will interrupt the life cycle of equine parasites.

Keep the number of horses per acre to a minimum to prevent overgrazing and reduce the fecal contamination per acre

Finally, you can monitor the effectiveness of your deworming program by periodically having your veterinarian do fecal egg counts.

Although not common, horses can pick up fleas in an infested barn or stable. In certain parts of the province, ticks can attach themselves to horses. A horse can become infected with lice if he comes into direct contact with another horse who is already infested.

Proper grooming is the best prevention for external parasites. If your horse does become infected, various insecticides are available. Consult your veterinarian for the most appropriate treatment.

Mange is a very contagious disease caused by several species of mites. Contagion can be spread by blankets, pads, saddles, bridles and grooming equipment as well as direct contact with the horse.

It is more prevalent in horses in poor condition. The best prevention is frequent grooming and good health. If your horse does get mange, consult your veterinarian.