Most dogs have no side effects at all. The ones that do almost always have mild swelling or soreness at the injection site that clears within a day or two. Serious complications are rare — but they are not zero, and it is worth knowing what they look like rather than being told not to worry.
What is actually reported
| Effect | How common | What to do |
|---|---|---|
| Soreness or slight swelling at the site | The usual reaction; normally gone in 24–48 hours | Watch it. If it is still there after a few days, have it looked at. |
| Migration — the chip moves away from between the shoulder blades | The most frequently reported complication | Not dangerous in itself, but ask for a full-body scan at the next check-up so the chip is still findable. |
| Infection at the injection site | Uncommon | Heat, discharge or a painful lump means a vet visit the same day. |
| Chip failure — it stops reading | Uncommon | Have it scanned at every annual visit. A chip nobody can read is the same as no chip. |
| A tumour at the implant site | The AVMA describes these as extremely rare and states that a cause-and-effect relationship has not been established | Any lump that grows, hardens or does not go away gets examined. |
Call your vet the same day if
- the site is hot, weeping or clearly painful
- a lump at the site is growing, or has not gone after two weeks
- your dog is lethargic, off food or feverish in the days after implantation
- the skin over the site is broken
Two things people get wrong
It is not painful the way people imagine. The needle is wider than a vaccine needle, so it is a sharper pinch than a shot. Most dogs react for a second and then forget it. It is not surgery and does not need anaesthetic.
A microchip holds no personal information and cannot track your dog. It stores one number. It has no battery, no GPS and no transmitter, and it does nothing at all until a scanner is held against it. Your contact details live in the registry that number is registered to.
The failure that is far more common than any side effect
From what we see running lookups, the problem is almost never the implant. It is the record behind it. A chip that was never registered — or registered to a phone number from three homes ago — scans perfectly and still leads nowhere. That is the side effect worth worrying about, and it is the only one you can fix yourself in five minutes.
Microchip resources
Find the registry by microchip prefix · Look up a microchip number · Universal microchip scanners · Register your pet’s microchip
