In Shelties, affected dogs as a general rule are not viable and do not live long. The Sheltie carries type III of von Willebrands, which is the most severe of the three levels. There are DNA tests that were developed to find von Willebrands in Shelties. It can be done at any age, and it will give three results: affected, carrier or non-affected. Shelties may also suffer from hypothyroidism, which is the under-functioning thyroid gland. It is an autoimmune disease where the immune system attacks the thyroid gland. Clinical symptoms include hair loss or lack of coat, over- or under-weight, and listlessness. Although small breed dogs do not usually suffer unduly from hip dysplasia, it has been identified in Shelties. Hip dysplasia occurs when the head of the femur and the acetabulum do not fit together correctly, frequently causing pain or lameness. Hip dysplasia is thought to be genetic. Many breeders will have their dogs' hips x-rayed and certified by the Orthopedic Foundation for Animals. The two basic forms of inherited eye diseases/defects in Shelties are Collie eye anomaly (CEA) and progressive retinal atrophy (PRA). Collie eye anomaly: An autosomal recessive inherited trait which results in incomplete closure of the embryonic fissure; seen almost exclusively in Collies, Border Collies and Shetland Sheepdogs. CEA can be detected in young puppies by a veterinary ophthalmologist. The disease involves the retina. It is always bilateral although the severity may be disparate (unequal) between eyes. Other accompanying defects (ophthalmic anomalies) may wrongly indicate a more severe manifestation of CEA. CEA is present at birth and although it cannot be cured, it doesn't progress. Signs of CEA in shelties are small, or deepset eyes. That is, the severity of the disease at birth will not change throughout the dog's life. CEA is scored similar to the way hips are. CEA is genetic, inheritance is autosomal recessive, this means that even a dog that shows no phenotypic signs of the condition may be a carrier. Breeders should actively try to breed this disease out by only breeding with dogs that have "clear" eyes or very low scoring eyes. A CEA score considered too high to breed with may still be low enough not to affect the dog's life.