Are Lumps at Vaccination Sites Normal?

 |  Apr 20th 2008  |   1 Contribution

Pebbles had her vaccinations a week ago Saturday.
She received rabies, DHLPPC, and Bordetella.
I discovered today that Pebbles has a round lump
on her right side on the muscle of her back.
I called the vet this morning and was told that
lumps after vaccinations are pretty common--it
should go away on its own in a week or two. She
told me to watch for signs that it's
hurting/bothering her and to bring her in if that

Is this the correct thing to do? Should I go
ahead and take her in? Or just watch it like the
vet said?

Sheena X.

It is not uncommon for dogs to develop small lumps at the sites where they receive vaccines. In my experience, the rabies vaccine is particularly likely to cause this reaction.

Vaccines, by nature, are designed to stimulate the immune system. This can cause lumps in two ways. First, the immune system can become active at the site of the injection, causing an infiltration of immune cells that leads to a small lump. Second, a lymph node near the injection site may become activated and enlarged for a period of time after the injection. These responses do not occur in every dog, but they generally are nothing to worry about.

I have seen post-vaccination lumps on dogs persist for several months. The lump on Pebbles should not grow, cause pain or produce a discharge or foul odor. These symptoms can be signs of a more serious reaction to vaccination, such as an infection at the injection site. As well, have Pebbles checked if she seems sick or lethargic in any way. The odds are good that the lump will resolve spontaneously over time.

Of course, if you are worried about Pebbles, it never hurts to have a vet check her out.

A note to people with cats: post-vaccination lumps also occur in our feline companions. However, these lumps (especially if they occur at the site of a rabies or leukemia vaccine) are potential harbingers of serious problems in the future. If your cat develops a lump after a vaccination, always have a veterinarian evaluate the area.


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