The cheapest thing you can do for your dog's long term health is brush their teeth

Not glamorous but the numbers are wild. The AVMA says most dogs and cats show signs of dental disease by age 3. Most. And a proper dental cleaning has to be done under anesthesia, which usually runs a few hundred bucks minimum and can go over a thousand if they need extractions. Meanwhile a toothbrush costs like 4 dollars. Couple things I learned the hard way: Use pet toothpaste, never human toothpaste. Human stuff can contain fluoride and sometimes xylitol, both bad news for dogs. The pet ones come in chicken and beef flavors so most dogs actually tolerate it fine. Start slow. First few days just let them lick the paste off your finger. Then a finger along the gums. Then the brush for literally 30 seconds. If you go straight to full scrubbing you'll lose the war on day one. Daily is ideal, but even a few times a week beats nothing. If your dog absolutely will not accept brushing, look up the VOHC (Veterinary Oral Health Council) accepted product list. Those are the chews and additives that actually have evidence behind them. A lot of the stuff at the pet store does basically nothing, the VOHC seal is the filter. Bad breath in dogs isn't "just dog breath" btw. It's usually the first sign of dental disease.