Math is used in animal medicine in the same manner it is used in medicine for people. One must calculate the dosage to administer to an animal. If too little is given, the medicine may not help. If too much, the animal may become ill or die.
Did you mean ARE animals used for medicines? If so then yes, they are. Although, in my opinion there should be a better way to test drugs instead of making animals unhappy, ill or even killing them....