Any OTC alternatives to expensive pills prescribed by vet?

Most medications prescribed for dogs are human medications at dog-sized doses. If a human medication is prescribed, you can take it to a regular pharmacy to be filled usually at a significantly lower cost than you can get it from your vet office. For example, Immodium can be used for diarrhea in dogs, and Zofran is commonly prescribed as an anti-emetic. My previous dog underwent cancer treatments for nearly a year, and during that time all but one of his medications (the only dog-specific chemo drug on the market at the time) were human medications that I often filled at a Walgreens because the vet didn't keep them in stock or because they told me it was cheaper at the pharmacy than from their office.

NEVER substitute medications on your own, however, and never try a new drug without running it by your vet for proper dosage and contraindications first. Though most of the medications used for veterinary purposes are different doses of human medications, there are some medications that are very dangerous for your dog. Very likely your vet will be more than happy to work with you to find cost effective solutions, and if they aren't, there's another vet out there who will.

As an alternative, some vets are willing to prescribe a generic of the medicine, and send the prescription to a pharmacy. Some pharmacys have cheap generics.