 Help with post surgery question
My little 8 month old viszla puppy was spayed last month but where one of the stitches is (they apparently sewed them below skin) the skin has risen into a blister-like lump. When I first saw it I thought it was an ant bite (as she's always getting those!!), but I looked at it more closely yesterday and it appears to be soft to the touch, getting bigger, a little greyer inside and a little red around base of it.
I'm thinking that the stitch area has become infected and is septic?? Is it potentially puss that is building in the 'blister-like' lump?? It doesn't seem to bother her, but I'm worried that it will not clear by itself. Unfortunately the vets are closed today. Can I wait until tomorrow or should I take her to emergency?? One of my friends suggested "popping" it, but I have disagreed with this as she's a dog and not a human and it's the stitch area and not sore that has went awry on a human!!
Any suggestions, guidance, reassurance will be very much appreciated, thanks. | 
