Healthy adult horses with thick winter coats, shelter and plenty of hay usually make it through the winter with little difficulty. But horses that are particularly young, old, clipped or otherwise somehow compromised may need you to think ahead a bit, so you can combat problems before they become serious.
On these three pages, you’ll find information on some of the common difficulties you’ll face, with advice on ways to make it through so your horse emerges healthy in the spring.
Laminitis and Winter
You probably think laminitis is solely a spring or fall thing, when the grasses are changing. However, there’s also a form of winter laminitis/hoof pain that has no trigger except cold weather and commonly strikes horses with a history of laminitis due to metabolic issues. These horses are difficult to treat and in the past have remained uncomfortable until the weather warms again. We now have some answers.
Animals use a variety of mechanisms to help them adapt to the cold. In horses, sudden cold snaps cause transient rise in cortisol. One of the effects of cortisol is to induce a degree of insulin resistance. This isn’t enough to cause problems in a normal horse, but it could be exaggerated in a horse with PPID (pars pituitary intermedia dysfunction, commonly known as Cushing’s disease).
Horses with known insulin resistance (IR) are made worse. Researchers studying IR have noted erratic insulin values during the colder months of the year.
Horses also naturally produce higher levels of thyroid hormones in the cold. This revs up their burning of calories by making it less efficient, so that more of the energy from food or burning body fat is lost as heat, helping to keep the horse warm. However, both PPID and IR horses frequently have their thyroid function suppressed if these other disorders are not under good control.
As temperatures drop, blood is shunted away from the legs and the skin surface to cut down on heat losses. The blood supply to the hooves is equipped with an intricate system of arteriovenous shunts that can bypass the capillary vessels in the tissues and directly move the blood from the arterial to the venous side to be returned to the heart. Cold activates this shunting. The normal horse’s hoof will periodically restore blood flow to the tissue level to avoid pain or tissue damage.
Unfortunately, hooves that have experienced laminitis may not be as able to withstand blood shunting. Studies have clearly documented clotting and hemorrhage in laminitic feet. The extent to which this can be healed will depend on both the severity of the damage and time since the active damage.
The Equine Cushing’s and Insulin Resistance group has been in existence for 10 years and at its current Yahoo location for eight years (http://pets.groups.yahoo.com/group/EquineCushings). You will need to register to use the group, but it’s monitored by Eleanor Kellon, VMD, our veterinary editor.
With over 8,300 members, most owners of horses with PPID or IR (often both), the group has an unrivaled amount of experience with these conditions. When we first started noticing unexplained hoof pain appearing in winter, the first thing tried was keeping the horses and their feet warmer with blankets, leg wraps and lined hoof boots. This worked for some, but for others it wasn’t enough.
One group member reported that the adaptogen APF had snapped her horse out of winter laminitis pain, which he had been suffering with for years. This makes sense since adaptogenic herbs work by keeping cortisol from undergoing wide swings. Auburn Laboratories (www.auburnlabs.com, 877-661-3505) then donated enough APF for a winter trial.
Ten horses with a history of having difficult-to-control winter hoof pain for several years were chosen. They were supplemented with up to 10 ml of APF once or twice a day. If there were any signs of foot pain developing they were also given 10 grams of the amino acid arginine three times a day. With this approach, all 10 horses made it through the winter without pain.
Many other herbs fall into the category of adaptogens, but some are known to cause increased insulin levels. Another one that is known to be insulin sensitizing and a potent adaptogen is Canadian ginseng.
In the late stages of the winter trial, some horses were switched to Canadian ginseng at 15 to 30 grams per day. This herb was successful.
All the horses used in this trial had their disease under good control before winter and there were no changes in medication doses or diet during the trial. If you have a horse experiencing hoof pain in winter and don’t know if IR or PPID are involved, or do not know if they are well controlled, you should always check ACTH and thyroid hormone levels and treat the horse as necessary to get hormonal control.