The use of ice wraps for horses is growing in popularity, with horses in all disciplines benefitting from cryotherapy. However, when using any equipment or treatment on your horse, it’s vital to know how to do so safely. This article discusses the question: how long should you ice a horse’s leg for?
When asked how long to ice for – in humans or horses – the standard response is usually 20 minutes. However, the more recent human research indicates that after exercise, icing for between 10 and 15 minutes with a temperature under 15°C is recommended.
So why do we still hear 20-30 minutes recommended as the optimum time to ice a horse’s legs for? Perhaps it’s because the longer we ice a horse’s legs, the better?
Icing and The Anatomy of a Horse’s Leg
The horses’ lower legs have no subcutaneous fat, no muscle and the tendons themselves have a poor blood supply. So, the impact of ice and compression should be accentuated on the horse’s leg. So why do some suggest icing for longer if the cold is going to have a greater impact on a horses’s leg?
Let’s start by using our understanding of human anatomy. The nearest possible human comparison to the horse’s flexor tendon is the achilles tendon, which is similar in structure and has little subcutaneous fat, is near the surface and also has a poor blood supply. Studies with Cryocuff, an ice and compression wrap, on the achilles tendon have shown that repeated periods of 10 minutes of ice and compression application are most effective. This is suggested to be because the most marked effects on the microcirculation are evident within the first 10 minutes after application, with not much further benefit to be seen thereafter.
Two studies in live horses (Kaneps, 2000; Petrov et al. 2003) investigated the temperatures of skin and the SDFT after ice water immersion. The SDFT temperatures dropped very quickly to between 10 and 15 °C within the first 10 minutes and then started to plateau. The implication is that blood flow to the limb may increase after 10 minutes to prevent a further decrease in SDFT temperature below ~10-15°C. This is the body’s natural response to prevent tissues getting too cold and causing damage.
Lab studies looking at the length of time a tendon cell could stand the cold demonstrated no damage to the tendon cells maintained at 10°C for 1 hour. Therefore, why not ice for longer than 10-15 minutes?
The Effects of Prolonged Icing and Compression
Icing a cell in a lab does not allow us to factor in the pain response. If you have ever iced yourself, it can be quite painful initially. Therefore, maintaining low temperatures for long periods could be uncomfortable for the horse.
Keeping tissues too cold for too long also has the potential to cause superficial tissue damage and nerve palsy after only 20 minutes. I have given myself ice burns after only 10 minutes – that icing session did not go so well!
Internal temperatures maintained under 15°C for long periods can cause inflammation and oedema and increase lymphatic permeability, as lengthy icing reverses the initial beneficial effects of cold (vasoconstriction). Vasoconstriction has positive effects as it restricts blood flow and limits bleeding into uninjured tissue. It also aids the anti-inflammatory response.
Ice and compression reduces blood flow even more than just ice alone. This is because the compression constricts the blood vessels further. By reducing blood flow, the inflow of heat from the rest of the body is reduced. The flow of oxygen to the area is also limited.
It is all of these natural effects of ice and compression that drives the cold in quicker and produces significantly colder internal tissue temperatures than ice alone. That quick drop in internal temperatures means tissue metabolism is decreased. This in turn slows the inflammatory response. A 10°C drop in temperature produces a 50% decrease in metabolic rate.
The Importance of Removing Ice and Compression
In a previous blog we discussed the role of inflammation and how that inflammation is required for the healing process too. In Cryochaps tests, it took as long as an hour for the leg to get back up to normal temperatures after only 10 minutes of icing. Therefore, even 10 minutes will have long lasting effects on the temperature of the leg and inhibition of inflammatory response.
Reducing blood flow also reduces tissue oxygenation. This has been proven in studies with the Aircast Cryo/Cuff, that uses both ice and compression. Oxygen is a double-edged sword because oxygen leads to free radicals, which play an important role in inflammation. However, it is also central to the healing process. Studies with the Cryo/Cuff in the achilles tendon injury demonstrated better tissue oxygenation after removal with an application time of 10 minutes compared with baseline, suggesting an increase in blood flow after removal and that increased oxygenation on removal is thought to kick start the healing process.
Cryochaps Ice Wraps for Horses
To summarise, the debate over cryotherapy is likely to continue and there are still gaps in our knowledge. To answer the question: how long should you ice a horse’s leg for, we can offer the following advice for Cryochaps users. In just 10 minutes of application there are many positive effects to be had and the body is unlikely in this time to try and start reversing the benefits of ice and compression. When using Cryochaps ice wraps for horses, we recommend applying the ice boots for 10-15 minutes before removing them. Cryochaps are available to purchase as a front or hind pair or as a set of four via our shop.