Causes of bad breath in dogs:

1. The dog’s diet is unhealthy. If your dog always eats human food, eats too greasy food or eats food with a pungent smell, it will cause bad breath.

2. The dog does not clean its mouth regularly. When the dog eats, there will be food residues left between the teeth. If the owner does not have the habit of brushing the dog's teeth, the food residues will rot and ferment over time, giving off a smell.

3. Dogs lack vitamins. When a dog’s body lacks vitamin B, it will lead to indigestion, oral diseases, and bad breath.

4. The dog’s digestion is not good. If your dog has constipation, diarrhea, or eats indigestible food that causes flatulence, food accumulation, etc., the smell of fermented food in the intestines and stomach will also be emitted through the mouth.

5. Dogs suffer from oral diseases. If a dog does not brush its teeth for a long time, it will easily form dental plaque and calculus, or the dog will suffer from oral diseases such as oral ulcers and periodontitis, which will lead to bad breath.