TRUE OR FALSE?
1. The words “laminitis” and “founder” mean the same thing.
False. Although these words are often used interchangeably, they describe specific stages in a complex disease. Laminitis is the inflammation of the laminae, the thin, pleated tissues that connect the coffin bone to the hoof wall. Founder is the deformity caused when the laminae stretch and fail, leaving the coffin bone without support so that it rotates (“sinks”) downward, pulled by the deep flexor tendon. Not all horses with laminitis develop founder.
2. Horses who graze dew-covered grass are at greater risk of laminitis.
False. Theories linking the location and timing of grazing to laminitis incidence abound, and this is one of the most common. But research into fructan, a plant sugar thought to be a key trigger of laminitis, suggests that the early morning hours might actually be the safest time for a horse to graze. Fructan levels in grasses are lower during the early morning hours, after a night when the minimum temperature was above 40 degrees Fahrenheit. Fructan levels are highest in the late afternoon or evening on a sunny day.
3. Particular types of bedding can cause laminitis.
True. Exposure to shavings made from black walnut (Juglans nigra) trees is a well-documented cause of laminitis. A chemical in black walnut called juglone, which can kill other plants and even earthworms, is the likely culprit. When exposed to black walnut shavings, horses typically begin to show signs of laminitis within one or two days. Bedding containing as little as 20 percent black walnut shavings can induce laminitis, so it’s important to learn what type of wood shavings you have before using them.
4. Very hard footing can precipitate founder.
True. Prolonged concussion against an unforgiving surface, such as asphalt, can lead to a condition commonly called “road founder.” The force of each step literally pulls the laminae from the hoof wall; this is one instance in which a horse can founder without having had laminitis. Simply trotting across a street will not cause road founder. Most horses who develop the condition have galloped on hard roads for miles or spent years working on asphalt without protective shoes.
5. A coffin bone that has rotated as a result of laminitis will eventually return to its original position.
False. Founder is forever, and a rotated coffin bone never regains its original position or attachments. However, corrective trimming and shoeing can help the hoof grow to match the new position of the coffin bone and form new attachments between the bone and hoof wall.
6. Particular dewormers and vaccines are known to cause laminitis.
False. There is no evidence linking any deworming product or vaccine to laminitis. That said, laminitis can be a complication of a high fever or systemic illness, so a severe adverse reaction to any veterinary product could precipitate the condition. If you suspect your horse is having such a reaction, call your veterinarian immediately.
7. It’s important to learn what caused a case of laminitis before treating it.
False. The appropriate treatment will be virtually the same no matter what has caused the inflammation of laminitis or the physical damage of founder. Nonetheless, in some cases knowing what precipitated laminitis may help you to prevent a recurrence or protect other horses from black walnut shavings, moldy grain and other dangers.
8. There is a “right” way to shoe a laminitic horse.
False. If one tried-and-true shoeing or trimming method restored laminitic horses to soundness, everyone would be using it. The reality is that there are varied approaches to helping horses with laminitis–from applying shoes backward to adding special pads to leaving the horse barefoot–and no scientific studies have yet proven one to be more effective than the rest. The best treatment or combination of treatments for a particular horse depends on the specifics of the case, which can change over time.
9. Laminitis occurs primarily in extremely fat horses and in ponies.
False. Risks increase with obesity, and evidence suggests that certain bloodlines are more susceptible, but with enough metabolic stress, any horse regardless of size or breed can develop laminitis.
10. By the time a horse is lame, the damage of laminitis has been done.
True. The 24 to 48 hours between the event or conditions that precipitate laminitis and the point when it is evident that the horse is in pain are known as the “silent period.” Once a horse begins to exhibit discomfort from laminitis, the condition is impossible to reverse. One track of laminitis research involves investigating the complex metabolic mechanisms at work during the silent period so that one day we may be able to prevent them from triggering the cascade of events that leads to pain and permanent deformity.
11. Clover and alfalfa are dangerous for horses who are susceptible to laminitis.
True. Clover and alfalfa contain relatively high levels of sugars and starch, both in pasture and as part of hay. These nutrients can start the chain of events that leads to digestive laminitis. Avoid giving clover or alfalfa to horses who are at an increased risk of laminitis, and check your fields periodically to make sure these plants have not appeared as volunteers.
12. Horses who have foundered are at an increased risk of another episode of laminitis.
True. A horse who has recovered from a bout of laminitis eventually grows new laminae that reattach the coffin bone to the hoof wall. However, those attachments are not as strong as the originals, and the horse will forever be at increased risk of foundering again. Also, many “new” cases of founder are simply an exacerbation of an earlier episode, which may have occurred unnoticed or when the horse had a different owner.
This article originally appeared in the April 2006 issue of EQUUS magazine.