It is recommended that you visit the veterinarian on a regular basis as this practice will keep your dog from harm's way. Also, following specific advice from the veterinarian can help keep your dog healthy for a long, long time. However, there are some unavoidable health concerns that requires your immediate attention; one of which is bad breath.
Cause #1 - Diet
The first thing you need to do is speak to the vet about your dog's diet. Do you feed him/her canned foods, or prepare something fresh at home. A healthy, young or adult dog should be given dry food along with the soft canned food. Keeping a balance between the different food textures should help.
Cause #2 - Tooth Decay
Many times, if gone unnoticed, a broken tooth or tooth decay can create issues. It could be possible that there is a piece of bone or food stuck in his/her teeth, and while brushing the teeth, you couldn't locate or remove it properly.
Cause #3 - Gastrointestinal Infection/Disease
If your dog has diarrhea, is losing weight, has blood in stool, has bad breath, constipated, doesn't want to eat, vomits, or the abdominal area has enlarged, it could be a sign of gastrointestinal infection. It should not be taken lightly. Although fowl breath is just a symptom, this could lead to a more serious issue.
Cause #4 - Gum Disease
Gum disease, a.k.a. periodontal disease, is a health problem related to age. Also, there are many dogs who have overgrown gums which can even go over their teeth. This is called gingival hyperplasia, very common with older dogs. Both these health concerns allow the growth of bacteria in your dog's teeth. This in turn results in bad god breath.
Along with these causes, there are other causes―mouth tumors, sinus infection, kidney infection, inflammation of tissue around his/her mouth, and diabetes, which is why consultation with the veterinarian is a must.
Foul Breath Remedies
If the veterinarian suggests, brush your dog's teeth daily or weekly. Use toothpaste made for pets and not the ones which humans use. Once in a month, take your dog to the veterinarian and get the teeth brushed professionally.
We discussed this earlier as well; feed your dog dry foods. Wet, canned foods can get stuck to the teeth and may stay there for a while. You can also give him/her tough dog biscuits. If there is evidence of plaque, it will be removed due to the biscuits.
Along with brushing the teeth properly, give your dog breath mints. This will temporarily eliminate the issue.
Give your dog a hard bone to chew on. You can improve his/her breath considerably with this regular practice. And also make sure that the bone is clean.