I take it there is no chance the dog is getting stung by a bee or wasp or fire ants and that there are no toxic plants she might have been chewing including mushrooms or houseplants? She doesn't grab toads or salamanders that might cause a toxic reaction like this? No special treats given just before this happens - a rawhide for example? a heartworm med? a flea preparation? odd allergic reactions can happen.
There are genetic diseases in the breed related to muscle issues that can effect the head area in part.
If these bouts coincide with the giving of immunization shots those can cause facial edema in some dogs
http://www.2ndchance.info/dogvacs.htm
Hypothyroidism has been linked with facial paralysis, laryngeal paralysis, muscular weakness and is a known problem in labs though usually you see it later in life. When hypothyroidism gets severe, it sometimes causes a "tragic" expression on a dog's face due to facial edema and it can impact a dog's alertness.
And Rocky Mountain spotted fever from tick bites can cause facial and limb edema
http://cvm.msu.edu/courses/mic569/docs/parasite/rmsf.htm
Also neurological issues are a possibility. Usually the head and face area have such a good vascular supply that swelling cannot occur but the droolng and altered mental state might indicate something neurological is going on.
I would suggest trying the following
Contact the breeder to see if any other pups show similar signs or if this is a possible known problem in the line
Consider consulting a veterinarian who specializes in internal medicine
Consider consulting a veterinarian who specializes in neurology
Ask your vet for specialist referrals or check here
www.acvim.org to see if you can find a local specialist to consult.
Hope this helps you!
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