This season we have fielded 27 inquiries about the deductibility of catnip. The rule is that expenses must be ordinary and necessary. Catnip is certainly ordinary. Whether it is necessary depends on who you ask and how recently they ate it.
If prescribed by a veterinarian to manage anxiety, a modest quantity may qualify as a medical expense. A bag of 14 grams over the year, at $8.50, is defensible. A bag of 400 grams with a stuffed mouse made from it is a hobby.
Hobby losses are not deductible. Neither, we regret to say, are the three days you spent on the stairs afterwards.