That’s a very good question. As well as the weight range falling between the medium and large breed foods, Rough Collies are also quite fine jawed, so I can understand why kibble size would be a concern to you. At Hill’s we consider a dog a large breed if it is 25 Kg or over when at a healthy adult body weight. That allows for variations in types within a particular breed. Most large breed foods have added glucosamine and chondroitin sulphate which can help maintain healthy joints, which can be an important consideration in larger breeds. My advice would be to weight your dog and choose the food the best suits for that weight. Any healthy dog over 25 Kg should have no problem with the kibble size of a large breed food.
By Libby Sheridan (Hills Pet Nutrition) (Professional Advisor)