re: My dog has a huge abcess thingy on her neck under the skin

Wow that's a big mass. Very well could be what Biff was describing which is called a Sialocele which is a defect in salivary duct between your salivary gland and mouth. Basically a build up of saliva under skin. Can be drained but sometimes needs duct to be removed. Being as hard as you described cant rule out possibilty of a lymph node. Either abscessed or cancerous. Have also seen masses like that be chronic inflammatory growths from a penetrating foreign body but those are usually quite painful. If it can be drained get some video.