I posted a photo of Bertie in the Christmas thread earlier and it's the first pic i've taken of him where this lump is clearly visable, maybe someone here has seen similar conditions on their dogs. We know he has a skin condition (probably eczema) on his lower back which causes dry, itchy skin, don't know if the two are related. I first noticed it about 3 years ago, luckily he allows me to examine and touch it. It feels like a water blister or liquid cyst, doesn't affect him in any way and isn't painful when touched. After a few weeks it began to shrink and eventually disappeared then became visable again after another month or so. It has been coming and going like this for the past 3 years. My family didn't want to take him to the vet incase it was cancerous or life threatening but after so long it hasn't gotten worse or any larger so rather than put him through any unnecessary surgery or treatment we've left it alone.