Understanding Compounded Drugs

Q. Some of my friends at the barn were talking about compounded drugs and whether or not they are safe to use. What are they? Should I ever use them?

A. The equine drug marketplace can be overwhelming. There are websites offering drugs for sale, products being sold at equine events around the country, and suggestions available from nearly everyone who has ever owned a horse. It's really important to sort through all of the information and consult with your veterinarian before giving anything to your horse.

First, let's clear up any confusion about what is meant by a "compounded drug." The American Association of Equine Practitioners (AAEP) defines a compounded drug as one that is created by manipulating an existing U.S. Food and Drug Administration (FDA)-approved drug. Examples include crushing a tablet to make a paste or gel, or adding a flavor to a drug to make it more palatable. For a drug to be legally compounded:

• It must be compounded by a licensed veterinarian or pharmacist for a single horse to meet a specific need;
• The horse owner must have a valid client-patient relationship with the prescribing veterinarian;
• There must be no FDA-approved, commercially available drug that will appropriately treat the patient; and
• The product must be made from an FDA-approved commercially available drug.

While the use of legally compounded drugs is recognized as an occasional necessity in equine health care, the AAEP cautions veterinarians to "limit the use of compounded drugs to unique needs in specific patients." Because of the time and financial investment required to bring a new equine drug to the marketplace, there are times when a legally compounded medication could be a veterinarian's only option. Conversely, some equine drugs are illegally compounded or manufactured. These drugs have not been through the stringent FDA approval process so they have not been demonstrated to be safe or effective for their intended use.

Learn more about horse husbandry and discover thousands of tips for keeping your horse happy and healthy in Understanding Basic Horse Care

Before administering any drug to your horse, ensure that drug is FDA-approved or legally compounded. A drug's FDA approval status can be identified by looking for a New Animal Drug Application number, or, for generic animal drugs, an Abbreviated New Animal Drug Application number. The six-digit numbers and the statement "Approved by the FDA" are usually found on the drug's label. A list of approved drugs can also be found by searching the database at Animal Drugs @ FDA.

Remember, if you have any doubts, consult your veterinarian.

Intestinal Parasites and Equine Nutrition

Infestations of parasites usually aren’t fatal to horses, but parasites damage the gastrointestinal tract, may lead to diarrhea or colic, often cause a pot-bellied appearance and a rough coat, and may adversely affect the growth of young horses. Owners may think some or all of these problems are dietary in nature and will try to overcome the problems by changing or increasing the horse’s feed. Actually, deworming the horse as needed will improve his condition without changes being made in feed type or amount.

Some common intestinal worms that affect horses are the large and small strongyles (redworms), roundworms, and pinworms. Stomach bots are the larvae of a type of fly, but they do not cause a major problem to most horses. Other parasites such as threadworms and lungworms rarely cause problems. The common signs of worm infestation are tail rubbing, pale gums, ill-thrift, colic, and poor coats. Severe infestation can also cause diarrhea or sudden death.

Large strongyles are gray, blood-sucking worms, approximately 20 mm long, that are often referred to as redworms or bloodworms. The most important of the group is Strongylus vulgaris. The eggs from adult worms living in the horse’s large intestine are passed out with manure onto pasture where, if the conditions are right, they hatch and develop into infective larvae. When eaten by a horse, the larvae follow a complex migration, passing through the intestinal wall to the inner lining of small arteries, then moving up these to the large arteries supplying the digestive tract. The larval migrations last five to seven months and the larvae eventually return to the intestine where they become adults. The migration of Strongylus vulgaris larvae can cause serious weakening of the walls of arteries and the formation of blood clots. When these clots break away and block smaller arteries supplying sections of the intestines, colic commonly results. On rare occasions, a weakened section of artery wall may rupture, resulting in sudden collapse and death. Another side effect is weakness. Although horses usually pick up worm larvae from pasture, any grassy areas around yards and stables that have been contaminated with manure will also be heavily infested.

Small strongyles are small redworms usually found in the large intestine. The larvae migrate into the gut wall, causing the formation of small nodules. Heavy infestations of small strongyles can cause ill-thrift and diarrhea. These worms have developed resistance to many of the common deworming products, and they are now a great problem to horses. The immature stage hibernates in the gut wall and then emerges to cause substantial damage to the gut.

Roundworms are a common problem in foals and yearlings. Roundworms are creamy-white, almost the thickness of a pencil and up to 50 cm long. You may notice the worms in droppings after deworming young horses. The adult roundworm produces eggs that have a considerable resistance to adverse conditions, and they can survive for several years on pastures and in yards and stables before hatching into larvae. This means eggs from one year’s foals can infect next year’s foals. Once ingested, the larvae migrate through the liver and lungs before becoming adults in the small intestine. These very active worms irritate the intestinal lining and can cause intermittent diarrhea, ill-thrift, and a potbelly. Pneumonia in foals is a common sequel to the lung damage caused by the migrating larvae. Heavy burdens of adult roundworms can cause intestinal obstruction, colic, and occasionally death.

Pinworms are up to 10 cm long and grayish-white. The eggs are eaten with feed and hatch into larvae in the small intestine. The adult female lives in the large intestine and lays eggs near the horse’s anus, causing intense irritation. The commonest indication of pinworm infestation is persistent tail rubbing. Pinworms are most often a problem of stabled horses. Although pinworms are not a particularly serious parasite, horses that continually rub their tails can develop abrasions and unsightly bare areas.

Tapeworms may occasionally cause colic, general unthriftiness, and diarrhea. Problems usually arise in late summer and autumn following infections in late spring and early summer. Although rare, acute symptoms of colic or sudden death can occur from blockage and then rupture of the bowel. Not all deworming products eliminate tapeworms, so check the labels of the products you are using.

Threadworms may cause diarrhea in young foals that are infected through the mare’s milk. Treatment of the mare on the day of foaling and rotation of foaling paddocks will assist control.

Lungworm infestation is a problem when horses are grazed with donkeys. Affected horses may show overall weakness or coughing, but clinical problems are seen more commonly in donkeys.

Trend Continues: Fewer Fatal Injuries to Horses on Synthetic Racing Surfaces

A database compiled by The Jockey Club indicated the incidence of fatal injuries in 2011 was lower when horses raced on synthetic track surfaces rather than dirt. The rate of fatalities on dirt was 2.07 per 1000 starts, while the rate on synthetic surfaces was 1.09 per 1000 starts. Fatalities on turf courses were 1.53 per 1000 starts in 2011. Races on dirt were the most numerous (283,745) followed by races on an artificial surface (45,700) and turf (50,362).

Approximately 93% of all racing days in the U.S. during 2011 were included in the analysis. Figures considered for the Equine Injury Database reflected only injuries that resulted in the death of the horse during the 72 hours directly following the race in which the injury occurred. Injuries, regardless of severity, that did not cause the death of the horse or led to death more than three days after the race were not included in the figures.

Collection of facts for the database was started in January of 2009. To date, information has been gathered for more than 1,160,000 starts (all starting horses in all reported races).

From Equinews

Dealing with Spring Allergies in Your Horse

equimed.com

With much of North America having a mild winter, spring has come early. Along with warmer temperatures and sunny weather, come allergies for many horses.

Spring allergies tend to strike horses in one of two ways. One way is skin allergies. With any allergy, a horse becomes sensitized to the offender - usually a protein of some sort. While initial contact may not cause any obvious problem, repeated exposures lead to reactions that can be most easily described as "over-reaction" by the immune system with release of histamines. Horses with skin allergies will itch, bite, rub, and roll to relieve the irritated area.

Common causes of skin allergies in horses

The most common cause of skin allergies in horses in the spring is insect bites. The Culicoides species of biting midges, or "no seeums," are first on the list of irritating insects, but horses can be allergic to virtually any biting insect. Insect saliva sets off an immune reaction and your horse may develop hives or weeping sores, especially on the midline of his stomach. Rubbing and rolling irritate the areas even more.

You may hear the terms "summer itch," "sweet itch," or "Queensland itch" used to refer to allergic reaction to Culicoides species' saliva. This is not just an Australian phenomenon, but can occur in horses in almost any geographic area.

Parts of the body most affected tend to be around the mane, tail, and the top of the back. Some horses also show signs of pruritus near the head and ears.

Carla Sommardahl, DVM PhD, Associate Professor in the Large Animal Clinic at the University of Tennessee, says dealing with fly allergies can be frustrating for horse owners.

"Certainly you do the best you can to keep insects off your horse. Using fly masks and fly sheets, including the ones with impregnated insecticides, may help. It is difficult to find fly sprays that consistently repel insects."

Horses can be managed to avoid fly bites to some extent. Change the time of day when your horse goes out. If Culicoides species in your area are active at night, your horse should go out during the day, andvice versa. When your horse is inside, try to have good ventilation - even a fan blowing on his stall - to minimize insect activity.

A horse with severe skin allergies may need medical treatment at times of peak irritation. These medications may include antihistamines and systemic steroids for short periods of time.Topical ointments or medicated shampoos may help mild cases

Managing respiratory allergies in horses

The other group of spring allergies are inhaled or respiratory allergies. Generally, these allergies are reactions to various plants, molds, and pollens. By tracking your horse's signs carefully, you may be able to isolate which pollens are the biggest problem. Of course, short of moving, your horse will still be exposed to local pollens every spring.

How can you handle pollen allergies? There are some management techniques that may help to keep your horse comfortable. Dr. Sommardahl suggests, "Keep your horse inside on hot and humid days, ideally with a fan or good ventilation. The heat and humidity simply add to his discomfort. Watch the pollen counts that your local weather newscasts provide. On bad days, your horse stays in, though he might be able to go out at night."

Keeping pastures mowed or bush hogged to prevent plants from pollinating can also help a bit. Try to minimize dust around your barn to prevent further irritation of your horse's respiratory tract.

Skin testing and blood testing to determine allergens can be used to develop desensitization injections for some horses. Most horses require a custom mix of allergens. It may take a year or so for you to see true benefit, but many horses respond at least somewhat.

Luckily, many horses also respond well to inhalant medications, such as albuterol, for respiratory signs. Inhalers can be used directly into the nose or with special face masks. Some horses need occasional treatment with inhaled steroids, as well. If possible, your veterinarian will try to avoid systemic steroids due to long term side effects.