Well, I wouldn't expect any dog to have "minty fresh" breath, but it shouldn't smell so bad that you can't be near your canine friend. There could be several reasons for your dogs' bad breath including a broken, decayed or abscessed tooth, mouth tumors, periodontal disease, gingivitis, diabetes, sinus infections, and inflammation of the gums, kidney disease, and gastrointestinal problems. This is not an exhaustive list, but you can clearly see that it's not as simple as "fixing your dogs' bad breath". You'll have to become a bit of a detective. We'll start with some trial and error.
If the bad breath is temporary, then it's quite likely just something your dog has consumed. Pay attention to what your dog eats (and gets in to). Some canned food will result in foul smelling breath. Raw meat can have the same results. A naughty dog that dines on the garbage regularly will also cause bad breath. If any of these are possibilities, then I suggest you find a way to keep you pooch out of the garbage and/or change his/her dog food to see if that makes a difference. If it is just bad breath from something your favourite friend has eaten, you can squeeze a drop or two of lemon into his water.
If you've ruled out anything consumed, it's time to consider a possible health issue. The most common cause of foul breath in your canine is periodontal disease. Just like people, food particles get stuck in between your dogs' teeth. Decomposed food causes bacteria and this combination results in plaque. This is no different than in humans. Plaque appears as a yellowish, brownish film on the dog's teeth. As with humans, untreated plaque will develop gingivitis and will ultimately progress into periodontal disease. All dogs need their teeth brushed. Brushing their teeth is the best way to proactively prevent this health issue and it is also one of the best ways to resolve it while it's in the early stages.
You can purchase toothbrushes especially for dogs, or you can use a soft bristle toothbrush. You may also want to consider a finger brush; a rubber cap with rubber bristles that goes over your finger. Some dogs aren't comfortable with the toothbrush and you may have better luck with the finger brush. If you start brushing your dogs' teeth when he/she is a puppy, there shouldn't be any problems with it as an adult dog. Even if you're starting with an older dog start by letting him/her sniff and lick the toothpaste. Make this a positive experience. Lots of praise and be very gentle. You may not get all the teeth brushed the first time. It's more important for both of you to have fun with it.
As for toothpaste... do not use people toothpaste. It shouldn't be swallowed and dogs don't like the taste. You can buy toothpaste for dogs or make your own.
Mix:
6 tsps. baking soda
2 dashes of salt
4 tsp. glycerine
2 tsps. either beef or chicken broth
You can try 2 tsps. of peppermint extract for the "minty fresh" breath, but no guarantee that you dog will like it. If there is evidence of swelling of the gums or gingivitis, adding a little crushed sage may help with the swelling.
It's important that you provide your pet with chewing opportunities. Dental chews can be purchased and will help to prevent tartar and plaque build-up. Bones, rawhide, dried pig's ears etc. are a great way to avoid plaque build-up. Be careful of the bones you choose; heavy shin and shank bones are best. Do NOT give your dog chicken bones. You can also take your dog into the Vet on a regular basis for a thorough teeth cleaning. It's also possible that there is an abscessed or decayed tooth that may need to be extracted. The only solution to this is a visit to the Vet. In fact, as we have already discussed, there are several health issues that could be the cause of your dogs' bad breath. Each of these would have to be diagnosed and treated by your Vet. During this time you should keep a close eye on your pet for anything out of the ordinary. Watch for symptoms like abnormal drooling, blood or other discharge from the mouth. Is your pet sneezing or is there a discharge coming from his nose? Is he pawing at his mouth? Is he having difficulty eating or not wanting to eat? Do you notice any swelling in his face?
Also check out what's happening at the rear. Is your dog constipated or does he have diarrhea? Is he passing gas? Bad odour from both ends... big trouble! Is he scratching himself? Does he eat grass but not his food? Is he vomiting? Anything you notice should be brought to the attention of his Vet.
The important thing is to remember is that there could very well be a serious health issue involved, and your dog doesn't have any other way to tell you or to ask for your help. If your pets' bad breath is not resolved, take him to his Vet.