17/12/2025
Great info for your equines with Cushing/laminitis over the cold
Winter months.
Equine Winter Laminitis
Brian S. Burks, DVM
Diplomate, ABVP
Board-Certified in Equine Practice
Acute laminitis is a severe condition of the horse’s hoof brought on by a complex, and often not completely known, series of events. Treatment must be swift, specific, and aggressive. The therapeutic goal in the acute phase is limiting the severity of the digital pathologies to limit the patient’s chances of suffering mechanical or structural failure of the foot. Although there are many different opinions concerning the treatment of acute laminitis there are basic principles on which most equine practitioners agree.
During cold weather, it is normal for horses to shunt blood via arteriovenous anastomoses which cools the feet but preserves core temperature. When oxygen tension becomes too low, the shunts open again to allow blood to enter the foot.
Some horses may have damaged vasculature or more constriction than is normal. Elevated insulin and cortisol levels make blood vessels more sensitive to vasoconstriction. Elevated insulin is associated with increased levels of endothelin 1, a potent vasoconstrictor. The stress of the cold may cause an increase in endogenous cortisol levels; increased cortisol causes vasoconstriction and reduced blood flow to the feet.
Horses with PPID, (equine Cushing’s Disease) or equine metabolic syndrome may have high insulin and cortisol levels make the vessels more sensitive to vasoconstrictors and more difficult to dilate. Their vessels are more constricted as a starting point. In normal horses, these AV shunts are expected to open to maintain circulation to the foot.
Insulin levels also increase in the winter and can become erratic, contributing to abnormal foot circulation, and predisposing the horse to laminitis.
Also affecting insulin is pasture grass. Stressed pasture grass stores high levels of sugars, leading to laminitis. Affected horses should not be allowed to graze until it has warmed up a bit and the grass has had time to respire and use some of the sugars stored overnight.
The reduced circulation causes pain, made worse by walking on frozen, bumpy ground. Pain and now the stress response, leads to an increased cortisol production, and this creates a vicious cycle.
Horses with PPID/EMS often lose their ability to thermoregulate, leading to stress and increases in endogenous cortisol production. Many horses also get less turn out time and exercise during very cold temperatures, which decreases insulin sensitivity.
Those horses that are prone to winter foot pain should be protected from the cold. They do not do well in the wind, rain, and snow. They may require blanketing and require distal limb protection via fleece lined boots or wraps.
Affected horses present much like any other horse with laminitis: sawhorse stance and a reluctance to move. There is usually no heat in the foot and there is often little sinking or rotation of the coffin bone.
Treatment of winter laminitis is like any other laminitis cause. Non-steroidal anti-inflammatory drugs may not work as well as for other causes. The underlying endocrine disorders should be under control before winter, limiting sugars in the diet and administration of pergolide or other medication. Thyroid hormone is used to improve insulin sensitivity (not to treat hypothyroidism, which is nearly non-existent in adult horses). It can also be useful to lessen the impact of the cold, hard ground as it concusses the feet. If you cannot offer softer ground, hoof boots can help protect from concussive forces and help keep the feet warm.
What you can do:
- prevent or limit access to grass during and after sunny frosty weather until the weather changes to milder nights and overcast days, and feed analyzed hay with sugar and starch levels below 10% instead. It is not the frost itself that is the risk, it is the weather conditions that cause the frost, so do not allow horses to graze once the frost has melted with the sun - wait until the grass has been able to respire and use up some of its sugar.
- keep feet warm and protected - use leg wraps/bandages, pads and boots on feet, warm deep bedding. Thick wool hiking socks can be great for keeping pony feet and legs warm.
- ensure feet are well trimmed/balanced - even the slightest tipping of the pedal bone onto the sole by high heels or pull on the laminae by long toes can exacerbate pain and discomfort when a horse is walking on hard rough ground.
- blanket well, provide good shelter out of the wind/weather - particularly for PPID/underweight horses. For overweight/EMS horses, cold weather can encourage weight loss so consider whether they really need a thick blanket.
- soak hay in cold water.
- cut back feed (calories, not fiber) if exercise/turnout is reduced.
- provide warm water for drinking to reduce the risk of impaction colic (not such a great risk when soaking hay) - particularly for older/PPID horses that might have tooth problems.
Fox Run Equine Center
www.foxrunequine.com
(724) 727-3481
