Accepted Answer

I wonder if perhaps the temperament change led to him grabbing the snake and getting bitten rather than the other way around.
It is possible the dog has a health issue causing the aggression.
One problem that is known to do this is a thyroid issue and those are fairly common in mature labradors.
Another which might apply as it sounds like he has a pretty good life with lots of activity is a tick carried disease.
Your vet can check for either of those.
This is certainly not typical behavior for this breed which is a concern. Another possibility is he didn't quite see what it was that bit him. He may have disturbed the snake and only seen a quick movement resulting in pain.
If that is the case he may be preemptively getting rid of fast moving animals living there to ensure the 'sneak attack' doesn't happen again.
I'd start with a good health check up and if that finds nothing at all then I'd consider seeing a veterinary behaviorists with him.
You may want to reconsider thoughts of him continuing as a stud dog if the atypical behavior keeps up as he might not be passing along proper lab temperament to offspring.
Hope this helps you!

Expert:	NancyH
Pos. Feedback:	99.5 %
Accepts:
Answered:	7/2/2008

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