Depends on why you are using the boots.

I'm assuming this is 4 degrees Celsius, which would be 39.2 degrees Fahrenheit. That's still in the danger zone for a horse prone to cold-induced foot pain. Plus, just standing in the snow could induce vasoconstriction. Waiting until temps rise above 50*F (10*C) and the snow melts is a safer situation.

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Lavinia, George Too, Calvin (PPID) and Dinky (PPID/IR)
Nappi, George and Dante Over the Bridge
Jan 05, RI
Moderator ECIR