Drooling or excessive salivation is normal in some breeds of dogs like Basset hounds, Bullmastiff, and St. Bernard. As your dog is Bullmastiff in which drooling is considered to be normal. Drooling in response to some specific stimuli like food, excitement, and heat etc is also normal.
But a sudden excessive drooling in dogs is not normal. It can be due to like gum & dental diseases, tongue injury, stomach disorders, mouth ulcers, tumors in mouth, and due to some metabolic disorders.
If your dog is showing some other signs like lip or mouth swellings, problems with eating and drinking, foul odor from mouth, breathing problems, vomiting, lethargy and weakness then take your pet to the vet.
But a sudden excessive drooling in dogs is not normal. It can be due to like gum & dental diseases, tongue injury, stomach disorders, mouth ulcers, tumors in mouth, and due to some metabolic disorders.
If your dog is showing some other signs like lip or mouth swellings, problems with eating and drinking, foul odor from mouth, breathing problems, vomiting, lethargy and weakness then take your pet to the vet.