Dog Odor

Question
In the last few days we have noticed our dog has an odor that smells like bad canned tuna. What is this from? And how can it be prevented?

She is a mutt (part rat terrier as we were told by the SPCA where we adopted her). She is about 1 yr 4 mo according to the SPCA. She had a bath/shampoo about a week ago. The smell seems to be different from the generic dirty dog smell, and it seems to come and go...sometimes stronger than others.

Answer
If she is not getting in to something rotten eiher outside or inside, then she probably has a seborrheic condition.  This means that her skin is producing oils that are being broken down into smelly things by bacteria on the skin.  Ask your vet for an antibacterial shampoo, like a benzoyl peroxide shampoo or a chlorhexidine shampoo and perhaps a two week supply of a good skin antibiotic like cephalexin.  If that takes the odor away, then that is what the probelm is. Also have the vet check the anal glands to make sure that the secretion from these glands is not what you are smelling.