
Vets are supposed to disperse the vaccine under the skin. Usually a good rub will do it but more often than not they just dont bother and pups get lumps.
However having said this our Dali went in for quite a big op earlier in the year (urate stones) and got an infection at his drip site that swelled to the size of a grapefruit. It got so big so quickly that it impinged on his nerves and he lost the use of his back legs, only temporarily though thank god. Whipped him down the vets for it draining off and he was right as rain.