By Erin Ryder, TheHorse.com News Editor
From a layman's perspective, cryotherapy (use of cold for treatment) for horses at risk of or just beginning the acute phase of laminitis just makes sense. The laminae are inflamed, the hooves are hot to the touch, so let's cool them down and keep them cold. Researchers get that, too. But there are still some questions on how this method works, and there are some issues when it comes to real-world applications.
Two factors have emerged as crucial to the success of this method: early intervention and duration of treatment.
Chris Pollitt, BVSc, PhD, head of the Australian Equine Laminitis Research Unit at the University of Queensland, shared some ideas on the function and uses of cryotherapy at the fourth annual Promoting Excellence Symposium of the Florida Association of Equine Practitioners (FAEP), held Sept. 25-27, 2008, in San Juan, Puerto Rico.
Pollitt said two factors in clinical trials have emerged as crucial to the success of this method: early intervention and duration of treatment. The earlier an at-risk horse can start cooling and the longer he can remain cooled seem to be paramount to the effectiveness of the treatment.
Pollitt said an at-risk horse should undergo cryotherapy as soon as possible--definitely before clinical signs of laminitis manifest. These can include heat in the feet, a bounding digital pulse, and favoring the affected limb, sometimes even "pointing" it in discomfort.
Trials using horses with laminitis induced just prior to and in the midst of therapy have demonstrated the method to be effective in preventing clinical signs and permanent damage. However, questions about whether cryotherapy can slow or halt the damage once it's started have not been answered.
In a horse with strong digital pulses, "If you use cryotherapy, you're chasing the shadow of the damage that's been done," Pollitt said. Exposed to cryotherapy, these horses might stabilize and not get worse, but the outcome mainly depends on what structural damage occurred.
As for duration of treatment, trials have shown that horses can tolerate cryotherapy over sustained periods. According to studies Pollitt cited, horses can stand in ice water for hours or days without the frostbite or other complications that make this approach dangerous for human patients.
"There's no real limit on the application of cryotherapy," Pollitt said, citing one study in which the horses remained in constant cryotherapy without damage for seven days. "I have no problem with leaving it on for as long as you think the horse is at risk from disease in other areas of its body."
In summary, the earlier you can intervene in a potential laminitis case, and the longer you can maintain treatment, the more likely you will succeed in preventing laminitis or reducing its damage.
The methods used for cryotherapy have varied, depending on who is applying it. Some have tried boots. Other opt for large tubs. Ice water slushies, sometimes in tire innertubes (tied off on one end, open at the other for the horse to step in), are also used. Either way, it's important to cool to the distal limb (from the carpus or tarsus down), to maintain constant low temperature, and to manage waste, in the case of the tub approach.
It's not easy--the horse must be maintained, perhaps for days, with water available and food, if it can be tolerated. A horse recovering from colic surgery or severe illness might not want (or might not be able) to stand in a cryotherapy tub.
"We need somebody to develop a really good cryotherapy boot or wrap application," he summarized.
While the kinks are still being worked out, research into this method continues to demonstrate its potential.