May
21
Written by:
Surgi-Care Center for Horses
5/21/2011 4:07 PM
An impaction is an obstruction of the gut. A section of gut can become impacted with numerous things such as sand, hay, gravel, or parasites. The ileum is the last section of small intestine feed material passes through before it enters the large intestine. The small intestine is approximately 60-70 feet long, and the ileum is the last 5-7 feet of it. After food leaves the ileum, it enters the cecum, which is similar to the human appendix, but much larger. There is a muscular section at the end of the ileum where it attaches to the cecum known as the ileocecal orifice. This site is important because it is commonly associated with ileal impactions. There may be changes and thickening at the ileocecal orifice with no known cause. The ileocecal orifice can also become thickened and less elastic due to damage by parasitism, specifically by the equine tapeworm Anoplocephala perfoliata. Regular deworming with an anthelmintic (dewormer) that is effective against tapeworms may be helpful in guarding against ileal impactions. Currently available for
this purpose are the pyrantel products (Strongid) and the ivermectins with praziquantel (Eqimax, Zimectrin Gold). Praziquantel is currently the only drug that carries an FDA label for use against tapeworms.
The type of ileal impaction that is of particular concern to horse owners in Florida is coastal Bermuda hay impaction. While the exact cause of ileal impactions remains unknown, in the Southeastern United States, ileal impactions are frequently associated with eating coastal Bermuda hay. Round bales of hay tend to be more frequently associated with impaction than square bales. The following scenario is a common one: The winter season begins, the first frost hits, and the grass dies back. Owners place round bales in their pastures to give their horses enough to eat. Horses frequently will gorge on the new hay for the first couple of days until they get used to it. The environmental temperature is colder, so horses are drinking less water. Coastal hay, particularly Bermuda hay, is very fine stemmed. This is more likely to pack up tightly in the intestine than broader leaf hays such as timothy. Consequently, a large amount of fine stems pack together, combined with less than normal fluid intake, and subsequently form an impaction. That is not to say that horses can’t get hay impactions if being fed from square bales, but because they tend to be fed in more limited amounts, the possibility of gorging is decreased. If the horses are used to the hay (and are fed hay consistently year round) the likelihood of an impaction is decreased. It is worth noting, however, that there have been cases of horses unaccustomed to coastal hay developing ileal impactions after having been fed one flake of coastal hay or less.
Horses with ileal impactions will have sudden onset of mild to moderate abdominal pain (colic). Very early in the process, they will respond to treatment with Banamine and mineral oil alone. As the disease progresses, the likelihood that a horse will need surgery to correct the problem increases. Very early in the disease your veterinarian may be able to palpate the actual impaction during a rectal examination. Later, the small intestine in front of the ileum will become distended with gas and fluid, which will obscure the impaction during rectal palpation. If the impaction does not resolve, it is likely that your veterinarian will obtain reflux when a nasogastric (stomach) tube is passed. Horses with ileal impactions will frequently have increased heart rates. They may also have decreased intestinal sounds. Both of these findings are typical of many types of colic. Exact diagnosis of an ileal impaction after the very early stages is difficult, because many other small intestinal diseases will have similar findings. If a horse with an ileal impaction does not respond to intensive medical therapy provided by your veterinarian, you may be referred to a hospital for surgical intervention. Ileal impactions can be fatal. If untreated, or not treated soon enough, they may lead to such severe distention of the small intestine and / or stomach that either of these organs can rupture. Therefore, if the horse is not responding to medical therapy, surgery is warranted.
What can be done to prevent this problem? Some owners may choose to avoid feeding coastal hay. If a horse has been fed coastal hay all if its life, and has no history of colic, there may be no reason to stop feeding coastal hay. If a horse has had an ileal impaction associated with coastal hay in the past, it may be wise to avoid coastal hay in the future. For normal healthy horses, the key is to keep the hay constantly available, even in the summer when there is plenty of grass. The horses may not eat very much of it during these times, but the hay will never be a novelty.
Make any changes in hay slowly over several weeks. If a horse is new, consult your veterinarian regarding the transition to your regular feeding program. Start supplementing hay before the grass dies off in the winter. Introduce hay slowly; don’t put a round bale out in the pasture if the horses are not already eating hay. If your horse is showing signs of colic such as rolling, pawing, lying down more than usual, looking or kicking at the abdomen, or he is not eating or has a decreased appetite, call your veterinarian immediately. Let your veterinarian know if the horse is eating coastal hay. Early intervention in any colic situation is key to survival. Colic, regardless of the cause, can be fatal. It should always be treated as an emergency.
Contact
Surgi-Care Center for Horses at 813-643-7177 or
email lkuebelbeck@surgi-carecenter.com with
any questions regarding this topic.