When we inharited Gidget from my mom she had been microchiped already so im not too sure about the cost......It never seemed to bother her any....kinda freaks me out though since it does move around from time to time
yuck. But if someone were to "steal" your pup or that it doesn't really do them any good...I mean it isnt like lojack or that where they can locate them. How ever if for some reason they got out and someone found her with 1/2 a brain they would bring them to any local vets and they can scan them for your info. If Gidget didnt already have one I would have gone ahead and got one for her while she got her "operation" :P I mean they are going to be "out" anyhow. I mean better to be safe then sorry...I guess i just figure if she were to get out and happened to loose her collar or someone were to take it off it is just a second defense. Besides I dont know if they range in size but Gidget's is MAYBE the size of a grain of rice.....