Its not so much that the needle is longer its that The needles used is a larger bore (thicker)needle than that used for vaccines. The actual microchip is the size of a grain of rice.
Some dogs act like your killing them, others don't act at all. I had my two pups done at 8 & 10 wks. The younger one didn't flinch at all, the older yelped for a second until he got a treat..neither acted like it was bothering them at all afterward. My vet wanted to do it when they were "under" during their spay and neuter at 5-6 months. I wanted it done ASAP because a lot can happen before 5-6 months old. Carson actually broke loose from his run 3 times! So I was thankful I chipped them when I did.
At the microchip clinic..all dogs were there..big, small, thin, fat, young and old..it didn't appear that younger ones, or thinner ones etc "felt" it more. Some acted like you were killing them, others yelped and were fine a second later, others didn't even notcie it at all
