We have a 11to 12year old female Field Spaniel. She has always been a house dog and always very healthy and eager to chase around the fields after her ball or whatever.But over the last three weeks she has lost lots of weight in spite of her still eating,He head is wobbling from side to side and she is constantley falling over when stepping off a curb or losing her balance.Millie is eager still to go out when I put my boots on and stands waiting but we can only get her to go a short distance in our grassed front street to do her business.Please can you help or advise should I take her back to the vet who suggested it was old age possibly, or a form of dementia

She's a senior citizen now and may have even had a stroke. Roll with her on what she is able to do, be patient, and find ways to accommodate her as much as possible. It sounds like she is a wonderful companion.

What did your vet say? Did he/she run any tests such as blood work? Did the vet do more than look at her age and give you a 'diagnosis'?