Accepted Answer

Sometimes dogs do this when hit with a bout of nausea.
Sometimes dogs eat like this when they have a problem with their liver or with anemia.
Drooling often goes with nausea too.
You might see if an over the counter med such as Pepcid or Tagamet or Zantac will help when the GasX does not.
You can read about dose amounts (and cautions) scrolling down on the pages here
http://www.petplace.com/drug-library/cimetidine-hcl-tagamet/page1.aspx
http://www.petplace.com/drug-library/famotidine-pepcid/page1.aspx
http://www.petplace.com/drug-library/ranitidine-hcl-zantac/page1.aspx
Pica, the eating of non food items, can be triggered by stress. Think about the way your or someone you know might get a 'nervous stomach' if they are stressed. When the dog has a reaction like this sometimes they eat odd things.
You might ask your vet about using a medication to help him be less stressed when traveling.
Drugs that increase serotonin levels such as Prozac can help if this is a compulsive behavior in response to stress.
A liver shunt can cause pica
http://clubs.akc.org/astc/health/astchlth/astcshnt/
You can read more on pica causes here
http://www.mountainvet.com/showpracfaq.cfm?FAQID=105&Private=0
But I think stress may be your dog's trigger.
You might ask your vet for a referral to a veterinary behaviorist. Medication and a training program may help end this problem. You are lucky to have gotten him this far with eating so many odd items as its so dangerous for dogs when they do this.
Hope this helps you!

Expert:	NancyH
Pos. Feedback:	99.5 %
Accepts:
Answered:	1/3/2008

Dog Expert:Rescue, Train,Breed,Care

30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics