I find it odd that most shelters require your newly
adopted dog to be chipped if they haven't inserted one already. Yet if the dog gets loose and a shelter gets that dog it has a 50/50 chance of getting scanned. And even if scanned theres no guarantee that the chip did not move, or that the scanner used can even read or detect that chip. To me microchips as a whole are a downside. They have been known to cause tumors which can become cancerous. As mentioned above, most shelters pick and choose which dogs they will scan, and even then the chip may not be read. A detected chip does not mean that the shelter is obligated to finding a scanner that can read the chip.
While it might seem like cruel and unusual punishment to us, dogs really can't feel a tattoo being applied. Albiet they will sure act like they do, but any unknowing canine would react to being pinned on their backs and having loud vibrating tool run across their inner thigh and stomach area. The benefits of a tattoo are lasting, but there is maintainance. Pros: A tattoo will never travel within the body, I know of no reports of a tattoo causing canine cancer, and it's not hard to find. Cons: Now for the maintainence, it's a doozey, depending on the dogs hair pattern, and coat length, the inner thigh/belly area may need to be shaven frequently to keep the tattoo visable, talk about hard work(Sarcasm).
Tags have benefits and disavantages. If your dog loses it's collar it's ID is essentially lost with it. Tags can also randomly be lost. My bitch Sam has no tags because she regularly loses them. The other down side is they can snag, and potentially be dangerous. If you're in cattle country you will likely find barbed wire and electric fencing, both of which can become snagged on a dangling tag. As I said tags also have benefits. If your dog likes to go off the trail. The sound of the tags would tell you where your dog is and how fast he's moving. It would also give any wildlife that might be endangered by him a warning of him coming. This will also likely reduce your wildlife sightings, but thats not always true.
Riveted, Buckle Tags, and ID Tubes
Dangling tags certainly aren't the only option.
Riveted tags come in various sizes and shapes, most can usually contain the same amount of information as a normal dangling tag
Buckle tags, or slide on tags are likely to last longer than dangling tags, as they dont bang around. as with the rivet tags they usually have the same amount of space for the information as a normal dangling tag.
ID tubes are growing in popularity is seems. One good thing about them is you can change the information the dog carries without having to buy a whole new tag, The tubes contain a small piece of paper, on which you can write whatever you need too.
Another option would be a customized collar. While space is limited with this option it does offer enough room for a phone number. Just like with tags though if the collar is lost the dogs ID is lost with it.
Remember whatever form of ID you choose keep the information up to date and if you're on a trail with your dog, use a friend or family members contact information instead of your own.