Have it examined by your vet. Most lumps at a microchip site turn out to be minor, but a lump is not something to diagnose from a web page — including this one.
What follows is what the possibilities are and what makes something more or less urgent, so you can have a useful conversation with your vet. It is not a substitute for that conversation.
What a lump at the implant site can be
- Normal post-implant swelling. In the days after the injection, mild swelling or tenderness at the site is common and usually settles on its own.
- The chip itself. A microchip is about the size of a grain of rice and can sometimes be felt under the skin, particularly in thin or short-coated dogs. It is firm, small, and does not change.
- Migration. Chips move from where they were implanted. The AVMA describes migration as the most frequently reported issue, and in most cases it does not affect the animal’s health — though it does make the chip harder to find on a scan.
- Infection or abscess. Uncommon, but it happens. Warm, painful, growing, or accompanied by discharge or a fever means a same-day call.
- Something unrelated to the chip. Dogs get lumps for many reasons, and one appearing near the shoulder blades does not automatically make it a microchip lump. This is the reason to have it looked at rather than assume.
Call the vet the same day if
- The lump is growing or changing
- It is hot, painful, red, or your dog reacts when you touch it
- There is discharge of any kind
- Your dog is off food, lethargic, or feverish
- It appeared long after the implant rather than in the days following it
- It is hard and fixed to the tissue underneath
What about tumours?
This is the question underneath most searches on this subject, so here is the honest position rather than reassurance.
Per the AVMA: tumours associated with microchips have been reported in dogs and cats, but they are extremely rare, and a cause-and-effect relationship has not been established. Laboratory studies showing tumours in mice and rats involved animals already used in cancer research, which limits what can be concluded from them.
The AVMA’s overall assessment is that microchips have an excellent safety record, complications are uncommon, and for the vast majority of pets the benefits far outweigh the risks.
None of which tells you what your dog’s lump is. That still needs a vet.
Should the chip come out?
Removal is a surgical procedure and is not routine. It is a decision for your vet based on what the lump actually turns out to be, not something to pursue because a lump exists.
If a chip is ever removed, remember the identification goes with it. Talk to your vet about what replaces it before rather than after.
While you are thinking about the chip
A migrated chip is still readable — it just needs a full-body scan rather than a pass over the shoulders. Worth mentioning at the appointment so they know to check properly.
And while it is on your mind: look the number up and confirm the registry record still returns you and a phone number you answer. A chip that reads perfectly and resolves to nothing is the far more common failure.
Common questions
Can I feel my dog’s microchip?
Sometimes, particularly in thin or short-coated dogs. It feels like a small firm grain under the skin and does not change over time.
How long should swelling last after implanting?
Mild swelling in the first few days is common. If it persists, grows, or becomes painful, call your vet.
Do microchips cause cancer in dogs?
Tumours at implant sites have been reported but are extremely rare, and causation has not been established. The AVMA’s position is that benefits far outweigh risks for the vast majority of pets.
Related from Peeva
Safety and complication information per the American Veterinary Medical Association. This page is general information and not veterinary advice — see your vet about any lump.
