Lump the size of baseball on the back of my puppy's back

[chidalgo713]

There is a huge lump, the size of a baseball on the back of my puppy's neck.  The lump has doubled in size since yesterday and am wondering what this could be.  It feels like there is liquid in it and everytime we touch the area, my puppy cries.  What could this be?  Can a stick a needle in it and try to pop it?

[Aleda M Cheng, D.V.M., C.V.A]

It could be a hematoma or bruise resulting from a traumatic injury, or insect bite.

The fluid acts to protect the injury, by cushioning the wound.   It can be painful due to inflammation.  But, just as you should not pop a blister please don't stick a pin in your dog's injury.  Please take your puppy to a veterinarian and have it evaluated, especially since the injury has occurred on the head in such a young pet.  Since bones are softer in the very young there is increased chance of damage to the brain and other soft tissues.

[ireneo]

No - do not stick anything into the lump. You don't know what's going on in there and you could introduce bacteria through a puncture like that.

Think back - did he get injured yesterday, a hard thump on the back or a fall. I've seen hematomas (a blood filled blister) come up quickly from an injury.

A trip to the vet would be best especially since it's causing pain and growing so quickly.