He may have a bad tooth or he may have something lodged in the roof of his mouth or he could have something stuck under his tongue. You may need to take him to your veterinarian.
Why Does My Dog Keep Licking His Mouth?
Lip licking in your dog can be part of self grooming because dogs also like to clean themselves. Following are some general reasons of lip licking in dogs.
1. Drooling
2. Stress
3. Nervousness
4. Self grooming
Drooling in dogs can be due to
1. Stimuli of food, heat and excitement
2. Mouth and gum diseases
3. Tongue injury
4. Stomach disorders
5. Mouth ulcers
6. Tumors in mouth
7. Metabolic disorders
So, you should get advice from your local vet.
1. Drooling
2. Stress
3. Nervousness
4. Self grooming
Drooling in dogs can be due to
1. Stimuli of food, heat and excitement
2. Mouth and gum diseases
3. Tongue injury
4. Stomach disorders
5. Mouth ulcers
6. Tumors in mouth
7. Metabolic disorders
So, you should get advice from your local vet.