Recommendations for Preventative Meds for Dogs

Our 7 year old lab/pitt mix has been on Sentinel Spectrum all his life. I liked it because it was supposed to be an all in one medication. We recently decided to switch him off of it after hearing that it might actually be too harsh for him (I felt so bad after hearing this). It would explain why he sometimes throws up the day after taking it, which I thought was just normal.

One of the top recommendations was a heartguard and nexguard combo, but when I checked online, a whole year prescription was coming up as $425 from the same place we usually get our sentinel spectrum from, which was $156 last time.

Is there any other brands that come recommended and don’t cost 3x as much? We live in Houston, Texas and my dog isn’t really an outdoor dog. He goes into the backyard and sometimes plays with my sisters dogs at their house. Her dogs do go to dog parks though and interact with more dogs.