I'm a big Avid Fan! They do have a scanner that reads most brands....
MiniTracker™ MultiScan 125
Reads Avid® HomeAgain™, Destron® and other microchips that operate at 125 kHz. Battery included. 7" long, 2 3/8" wide, 1" thick.
Some other brands scanners will only read their own chips!
Scary!!! But I know my local animal shelter has a universal scanner... you can purchace them as stand alones.
Ask your vet if they have one next time your in... and if they say no... ask them WHY NOT???? Insist they look into it! They really do listen to their customers... And call your local shelters as well and ask what they are using!!!! If you don't get the answer you are looking for write to the city! Or start a petition! Its not safe for them not to be using this technology when its avalible to them! And its CHEAP! Cheaper than housing dogs that could be back at home!