Mouth Sores
Mouth sores are more common in older pets who have other health problems such as kidney disease or diabetes. Dental disease is also a common cause.
When a pet has a sore in their mouth, often they will paw at their mouths and may also drool. A lot of times they will refuse to eat since their mouth is very tender. Lack of nutrition can make this problem even worse than it already is.
If your dog has a sore in its mouth, get the dog to the vet. The sore could be caused from an infected tooth, or the dog could have a foreign object wedged inside his mouth.
To help relieve some of the pain, you can try to offer the dog some crushed ice- the cool ice will help to numb the pain. The dog should be put on a soft food until the sore is healed. If your dog is sensitive to switching foods, try offering some boiled chicken or hamburger with rice. Make sure it's room temperature before you serve it. The bland food will not upset the dogs stomach, and it is soft enough that it wont cause the dog any discomfort.
The dog should get to the vet as soon as possible to avoid any further problems.