I plan to have my pup microchipped at his first vet visit in a couple of weeks. My question is has anyone got the under the skin GPS tracker or the GPS that goes on a collar or harness? Any recommendations/preferences or advice? I'm personally leaning towards under the skin just because it's so easy to remove otherwise. Thoughts?

I have a micro chip (HomeAgain) and chip monitoring for my dogs. Your standard microchip that specifically is checked or found with the scanner. I also have the Tagg 1.0 GPS pettracker supported by whistle. The platform was bought by Whistle and there have been a few growing pains due to transition but it is about back to where it was when just Tagg owned it. I am happy with the money and support. (It does activity tracking too!)
Do not know anything about a gps microchip for under the skin that can find the dog location via gps not scanning the actually dog. I thought this device was still in the development stage. SO I am not much help. But here is a link to a topic already in play about the Whistle platform (collar) WHISTLE on the Forum

Pandora, let's get to the reality of the questions.

The standard chip (from AVID or HomeAgain, for example) used in most pets is a standard passive RFID style which means the scanner must be located within a couple of feet of the animal.  Obviously they require that your pet be with someone who can scan for the chip, contact the service (and they all communicate with each other, I've been led to believe) and then contact you to come get your dog.  If your dog is 'dog-napped' the chances are good that the culprit will be aware of that and avoid situations where the dog would b scanned.  That all said, it can be an important aid in finding a dog that's run-away / been lost.

GPS Trackers that are collar units, such as the one Colleen mentions, are active.  They, in general, read their location from the GPS Satellites and then relay that information to a receiver via the cell tower networks.  There is another, such as the Garmin Unit, that relays it's information directly to a hand-held unit but the range is limited, in the 18ghz frequency range (where did I pull that Frequency from? see the edit) the signal can be stopped by almost anything so line of sight to the animal is a virtual requirement.  The other downside is that they tend to be considerably more expensive that the standard GPS units, Garmin's T5 for example costs $250 - presumably since they're a one-time purchase as opposed to an ongoing subscription.
If you live in an urban area, the collar based units are well worth their cost, in my opinion.  In the very rural area where I live they would not work since there are no close cell towers.

Subdermal GPS - with the current state of the art doesn't exist - though a scan for "sub-dermal GPS" produces some interesting results.  The limitations are inherent in the design, the 18Ghz range used won't penetrate an animal body - if a signal can't be transmitted, you can't be found. I'm sure everyone who's used a cell phone has suffered the aggravation of "losing signal" when they were separated from the tower by a building or a tree. The power level necessary to reach an antenna would cause burns to a body, internally that could be critical.  Even the collar based units have caused some RF irritation when improperly mounted.

Sum:

• the standard injected RFID chip at $75+/- is probably the best bet when it comes to having a lost dog returned.  
  
• The Tagger style systems are better and while the initial cost is about the same ($79 - hmm, they have a $15 dollar discount that ends today) there is an ongoing service fee of $9.95/month [less for longer term] which would bump the cost over a long run.  Significant downsides outside an suburban/urban area.
  
• Subdermal GPS - interesting and possibly a future possibility, but not at the moment.
  

Edited to add:  Garmin says that their units use the MURS frequency ranges but then fail to say which.  There are five  frequency ranges, one in the old CB radio range at 21mhz but with only 2 watts allowed power it'll have problems reaching much over a couple of miles.  Others in the 151 / 216 / 460 Mhz area (similar to HAM handheld units) at two watts are going to be stopped by virtually any obstruction.

Okay so what happens when I drop a ton of money on a gps collar and service and someone steals him and takes it off? I live in a major city where you have to watch your surroundings. People will watch you walk your dog and follow you to see where you live just to steal your dog when you aren't around. Call me super precautious or paranoid or whatever but I want to be able to find him if anything ever happened.

Well Pandora the mirco chip only works if a vet or some one scans it.
And a collar only works if it stays on.
Yep no good situation. People are jerks.

Obviously the gods didn't like my first response, so I'll try again.  As my grandfather would have said "You're using a hammer to drive a screw, get the right tool!"

A quick Google for "dog theft in St Louis" agrees, you're again in a period where dog theft is all too common but not so bad as it was a couple of years ago apparently.  But then, so is car theft and general burglary - I never did like St Louis, sorry.

Hopefully, people don't park their 2015 Mercedes on the street and leave it overnight - probably not a wise choice.  They lock it up in a secure garage or a secure lot somewhere.  But, they also have locks on the vehicle, and a lojack and maybe a factory installed GPS - all 'just in case'.  Nothing, short of never putting the car on the street is going to deter a determined car thief; I think it safe to say that if you have today's equivalent of "Lassie" and let her roam your neighborhood at large then she's gonna be gone.

Our emphasis has to be on keeping the animal safe to begin with.  Depending on where you live, secure - solid - doors are the beginning; if you live in an apartment house then monitored video cameras are a good back up.  You live in St Louis, a city notorious for it's crime rate - I'm sure you've taken all the steps necessary to secure your living environment.  Those, and their like, are the tools for keeping him safe.

If I steal your 2015 Mercedes, the first thing I'm going to do is to disable the GPS ... cutting down a car with a working GPS is dumb.  But cars aren't known to go off wandering on their own which our four legged friends will do. The GPS systems are designed to help us get our pets back in that type of situation.  The 'chip' is the equivalent of the serial number that's stamped on most major parts of a vehicle, they do nothing to help get a stolen vehicle back - they help identify the vehicle when parts enter the 'part stream' but only if the parts house are legal and looking.  The chip we all use identifies our dogs to someone who is looking for a chip and then knows what to do when they find one.

The Animal Legal Defense Fund has a page of comments and suggestions and since you're looking at GPS systems then I'm pretty sure you're aware of many of those suggestions.

So, at the risk of sounding redundant:

• You keep your pet behind secure and locked doors when you can't be with him
  
• You put the GPS on him so that you can find him when he slips out the door and takes off down the street.
  
• You chip him so that when he's picked up by lawful authority or a concerned citizen he can be identified and returned to you.
  
• You pray that you don't have to ever resort to using any of them.
  

Not the answer you were looking for, I'm sorry.  I think all of us would be willing to invest in a technology that would ensure a lost / missing pets return.  At the moment, though, I can't find such.

Al - you said it all better than I could have.

Theft is a worry I have, too, particularly since Ami is so friendly. We do not have the crime rate that St.Louis has but I still worry. (My older son's bike was stolen and reported to the local Sheriff's office - 2 days later, he was walking down the street with his young son who spied the bike, dragged Daddy over to look at the "really cool bike" and Mr. Sheriff looked, said, hey, wait a minute and the bike was returned to us later that afternoon - small town living has its attributes.)

But, it has just come to my attention that up in St. Lawrence County there is a dog theft ring operating - 17 dogs stolen over the past year, so I'm a bit more nervous, though St. Lawrence is a loonnnnng ways from here. Nice thing about Archer (sometimes) is he barks at anything out of the ordinary. Both are chipped. Haven't considered the GPS thing.

St Lawrence is even up above my stomping frowns in Jefferson!! My first thought was "Why?" then it dawned on me that it's not all that far from the labs midstate and since most of the dogs that were stolen are purebreds, probably a bit further south to be flipped in NYC.

If we had cell towers here, I'd do the GPS - especially after Misty went missing on me; at three years since, I have to assume she got herself into something on the desert that she couldn't handle - but if we had cell towers, I could have found her ... couldn't I?

The theory is flipping in nyc or dog fighting but more v the first. Most of b the dogs are intact purebred males but not breeds suitable for fighting. The article also mentioned forged papers so I'm wondering if backyard breeders are becoming even more unethical...

Constant vigilance is essential. I always am with Anya when she's outside. I never look down at my phone at the dog park, I don't let her wander...even if she's in a fenced yard I sit out with her. In my area, so many dogs have been snatched out of backyards while the owner was home but wasn't watching the dog.

My pup is microchipped and tattooed. The issue with the microchip is that they're not universal; you have to hope that if your dog is found, the vet or shelter has a compatible scanner or you're out of luck. At least the tattoo is readable by anyone (who would even think of looking for it!).

The last thing is on her tag with her name and my address and number, I also had REWARD IF FOUND engraved on it. If anyone finds her or steals her, I want to make sure they know I'll pay whatever to get her back which would be easier than selling her.

I'm a paranoid dog mom....she's my baby!

I love the idea of adding reward if found to his tags. I haven't had him microchipped yet. I have to find a vet I like since he's about due for his second round of shots. I'm waiting for his akc registration paperwork and pedigree to get back. Not sure how long that usuallyvtakes...I ordered it online about a week ago. What does your dog's tattoo read? And does the vet do that?

Tattoos are common among show dogs, not sure why. Hers is a simple identification number & letter. We had it done at the vet the same time she was spayed, so she was already unconscious. The tattoo is very quick to apply.