
Hi Claire,
A bull terrier is no different in its nutritional requirements to any other breed of dog. They need a balance of carbohydrates, fats and proteins, from which they also obtain essential vitamins and minerals, eg calcium, phosphorus, potassium, iron etc etc etc.
Carbohydrates provide 'slow-release' energy and dietary fibre, fats provide concentrated energy and 'essential fatty acids' and are carriers of certain vitamins, and proteins are important for growth, tissue maintenance and repair.
Hope this helps.