Experienced breeders can usually identify this in the new born puppy, which is typically smaller than others in the litter, and has a characteristically slimy feel. As an affected puppy develops it usually becomes obvious that it is a "runt" but it is not just small - about half the size of normal puppies by six weeks - its feet are flat and splayed, it has skin problems and is often more than usually aggressive. The skin is prone to infections and the feet pads are horny, this keratinisation often spreading to other areas. The root of the problem appears to be a zinc deficiency, but zinc supplementation does not help as the puppy is unable to metabolise it. An affected puppy faces a short and very uncomfortable life, which may be prolonged by expensive treatment, but there is no cure. It is generally considered kindest to the puppy to have it euthanased as soon as the problem is diagnosed. So far as is known, this disease is unique to Bull Terriers, so very few vets have seen it or know about it. The disease is inherited as a double recessive autosomal gene, so that two healthy parents may carry it, although not having any symptoms, and yet produce some affected puppies.