Hi Vicki, It is not sufficient to just measure the T4. A full panel needs to be done and Michigan State University or Cornell will do this for your vet and interpret the findings. It is potentially dangerous to boost a dog's thyroid level too high, there are diseases that can result. If your boy is aggressive you need to find yourself a behaviourist registered with the Association of Pet Dog Trainers who can properly evaluate him. Aggression is often misunderstood and may result from a multitude of causes. Can you describe specific incidents of his demonstrating aggression and the circumstances leading up to it and how you dealt with it at the time. What is his age, is he neutered, been socialised and obedience trained? Has he demonstrated shyness as a puppy and is now overly defensive? Are his joints sound? Many things to take into account so it would be best if we can steer you towards a behavorist skilled in dealing with aggression.
Berners tend to be on the low side of normal and if he is truly hypothyroid and actually needing supplementation then you must start with low doses and test every two weeks until the right dose is established and then retest at least every six months. Rose Tierney
