depends on the case. there is a canine-insulin product out that we're supposed to use, because it's the only thing licensed for use in dogs, but it's always on backorder. so i started this one on glargine insulin, figuring that SirF would be more likely to comply with single-day dosing than twice day dosing. My cat is on PZI. used to use a lot of Humilin before they took it off the market.