We have a ten year old Golden Retriever who has been neutered because our vet suspected he had a testicular tumour. Since the operation he is more withdrawn; sleeps a lot more and at times seems almost ‘depressed’ and has aged suddenly. He is otherwise in good health, enjoys his walks and he could eat for England! Could the loss of testosterone could explain this change in personality?

A: Yes, this is possible. The sex hormones have an important effect on mood regulation in the brain, so when the source of testosterone (or oestrogen when a female dog is spayed) is removed, it is not unusual to see a slight change in character. These effects can sometimes last for a few months but the good news is that in many of these cases, things return to normal over time as the hormonal balance is naturally restored. A general anaesthetic itself can also cause some confusion and temporary depression.

Neutered animals do sometimes have a slightly slower metabolism after the surgery, so you may find he needs fewer calories in his food to avoid gaining weight. There are many weight control or weight loss diets available (talk to your vet about these) but as you know, I am a big fan of low carb, raw meat & raw vegetable diets, but that’s another story.

If the changes are significant and long lasting, you might also want to ask your vet to check his thyroid hormone levels.