My 2 year Rat Terrier eats tissues from the trash as well, but so far I have not experienced her have issues like you are having with your Jack Russell. I just wish I knew how to make her stop. I hope your doggy feels better soon. Keep me posted.
Your JRT has a serious problem: bowel obstruction. If he is currently behaving the way you describe, you need to get him to a vet right now. Yes, this is an emergency and could be fatal!
If the obstruction has passed and he is pooping with no more problems, you dodged a surgical bullet. Frankly, he's lucky to be alive if this happens on a regular basis.
It's time to invest in trash cans with self-closing lids. I've had to do the same thing with our dogs. They just can't resist used tissues and other smelly items that end up in the trash - particularly bathrooms. This is a gross story, but I had a friend of ours staying with us for a few days, and she was on her period. Yup. The dogs had a field day with the used pads. Luckily I was able to clean it all up before my friend or husband found out and saved her a lot of embarrassment. Also lucky was that the dogs only shredded the pads and didn't ingest any of them. Since I had a hysterectomy, that particular problem had never crossed my mind, but I bought new trash cans that very day. :-)
I agree 100% with Jaybay's assessment of both of these situations. Lidded trash cans are needed immediately, and Riley10158, you need to have your dog examined immediately by your vet to make sure there is not a potentially fatal blockage in there.
Tissues do not dissolve when a dog eats them, they will continue to just wad up in the gut, causing a blockage that will kill the dog if it is not removed. Very small bits of tissue are nothing to worry about, but if the dog is raiding trash cans and ingesting several tissues at a time, this is definitely problematic and needs to be addressed immediately, both in terms of how the trash in your home is handled and medically as far as your dog is concerned.
Please post back and let us know what the vet said. The dog should NOT be painful upon palpation and definitely should not appear to be in pain when you merely pick him up if there is nothing serious going on.
Ghilly