I'm not sure whether you in theory could...
But I wouldn't.
The horse might freak with the feeling of warmth & if they have a reaction they can't exactly tell you.
Having had a reaction to Deep Heat myself I can say it wasn't pleasant to feel like my skin was burning to the point that I had to strip down to a short sleeved polo-shirt in below 0 degree weather
Yeh this is what I thought, I just wondered as there is a lot of posts on here about using human products horses so I thought this may applyfor this kind of product.