Study Shows Transdermal Carbon Dioxide Has Potential to Stimulate Hoof Growth
A recent study published by the American Veterinary Medical Association explored the efficacy of transdermal carbon dioxide on hoof growth. Authors and veterinarians Meredith Rudnick, Holly Stewart, Modesty Burleson and David Levine cited an average of 0.19-0.28 mm/d in hoof growth for a normal, healthy horse, which is affected by environmental, nutritional and metabolic conditions. Poor hoof growth can lead to cracks, pain and lameness issues.
“Transdermal or transcutaneous CO₂ has been used in both human and rodent models, as well as in human clinical trials, to improve the healing time of wounds and degree of soft tissue injury healing,” say the authors. “Trancutaneous CO₂ has been shown to have a vasodilatory effect of local tissues in microcapillaries as well as increase blood flow rate. The production of hoof wall as it relates to its distal growth is directly dependent on blood supply to the foot.”
This 10-week study enrolled 14 adult Warmblood mares ranging from 6 to 25 years old and attempted to control for footing, time of year, age and nutrition by sourcing horses from the same herd during the same season with similar management practices, according to the study.
Nonpregnant or retired broodmares were eligible only if they “were bilaterally forelimb sound and systemically healthy as evaluated by physical examination.” All horses were also barefoot for 3 months before and during the study.
Methodology
Three horizontal lines were made on the dorsal hoof wall of each foot using a dremel and measured by a caliper: 1 cm from the coronary band with one on the midline and one on each lateral and medial quarter. Measurements were taken by two equine professionals who did not know which treatment group they were evaluating.
The broodmares were split into two groups. The first was administered transdermal CO₂ and the second was administered room air. Forelimbs were wetted and a product bag secured before CO₂ or room air was administered. Each horse underwent treatment for 30 minutes 3 times per week for both 5-week cycles. After 5 weeks, groups were switched and hoof growth monitored. Follow-up measurements were taken from the coronary band to the horizontal lines in the hoof wall.
Results
“At the 5-week point, hoof growth was increased in treated feet at 2 sites, the left front medial and right front lateral,” the study says. “Hoof growth was not different between treated and untreated feet in the other locations.”
Most percent change in growth happened between 0-5 weeks. The change in hoof growth was 27.92% with a 11.81% standard deviation (SD) in the left medial quarter in CO₂-treated hooves and 18.18% with a 10.19% SD in hooves treated with room air. In the right lateral quarter, hooves administered CO₂ showed a 25.69% change with a 8.36% SD, while the room air group had a 17.59% change with a 10.6% SD.
“At the conclusion of the study, the percentage of change between baseline versus 10 weeks and 5 weeks versus 10 weeks showed no significant differences at any of the 6 hoof locations,” the authors say.
It was expected that all hoof locations — lateral, midline and medial — would experience the same response to the CO₂ treatment, so the authors recommend further investigation into the inconsistent growth rate between the midline and lateral/medial quarters.