Ok, thanks for that information - very helpful!
What you are describing with Sam drooling so profusely is called ptyalism.
There are a number of possibilities for what may be causing this.
1. A foreign body -
Your dog could have something like a grass awn or a sharp sliver of stick or raw hide penetrating the tissues in his mouth. Grass awns are notorious for getting stuck in tissues as they are barbed and tend to migrate upwards. I have often found with chewers that they have a cut or a foreign body in the soft palate at the back of the mouth. I have had to give an anesthetic to find it usually because it is so far back.
2. A tooth root abscess -
Teeth have very long roots that extend close to the nasal sinuses. With a tooth root abscess, the infection can actually get into surrounding muscles and tissues and cause pain and with infection there can be ptyalism.
A tooth root abscess is often caused by a fractured tooth, with a slab fracture of the carnassial (big molar at the back) being the most common one I have seen. If your dog will let you look around in there, you may be able to find it. You have to really lift that top lip up and stretch it back to see all the teeth at the back. This may be best done by a vet as your dog may not be wanting a dental exam at the moment!
3. Masticatory Muscle Myositis (MMM) is another possibility.
With this condition, the muscles in the jaw become very inflamed, making it painful to open the jaw. It is caused by the dog's own immune system attacking the muscles. I think this is unlikely since your vet surely would have noticed it Sam had pain when the vet opened his mouth to look around in there.
Here is more about it:
4. Ingestion of something irritating.
Dogs that chew on plants containing calcium oxalate crystals will have local irritation and copious drooling. Dieffenbachia species will do this (dumb cane is a house plant in this family, but there are various others). Milk or other calcium containing products (yogurt, ice cream) can help to relieve the symptoms. Here is more about this plant:
5. It is possible that Sam got stung by a bee or wasp on his tongue.
This might not be visible, but could still cause drooling. If you are getting some cooler temperatures there this would be even more likely as the bees would be more sluggish and easily licked up by an inquisitive pup.
Here is more: http://www.petplace.com/dogs/allergic-reaction-to-insect-stings-in-dogs/page1.aspx
If your dog came in to my clinic, I would start with checking his temperature and doing a dental examination. Depending on what I found, I would consider starting him on some Benadryl just in case this is an insect sting, and I would offer milk-products (yogurt, ice cream, cottage cheese are less likely to cause diarrhea than straight milk) in case of an irritant like dumb cane.
When I treat them with BENADRYL (diphenhydramine), the dose that I use is 1mg/lb. Is she about 50lbs? It comes as 25 mg tablets, and if she is 50lbs, I would give her TWO TABLETS. This can be repeated every 8 hours for 24-36h.
Here is more about Benadryl:
You should see improvement within 30 minutes.
If this did not help, I would give anti-inflammatories and anti-biotics in case there was a cut in the back of the throat.
If he still did not improve, my next step would be to give a very light anesthetic in order to do a retropharyngeal exam and take some dental x-rays and take a biopsy of the chewing muscles if I were concerned about MMM.
Here is more about ptyalism:
So, if he were my patient, for now I would try milk products and Benadryl. If this persists into next week, then I would suggest you make an appointment to see your veterinarian for a re-check.
If you feel that this has been helpful, please hit the "ACCEPT" button and leave feedback.
If you need further information click on reply and I would be happy to provide it.
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.