DWARFISM
| There are miniature and toy versions of “standard” size breeds, but this is not the same as dwarfism, the latter being the result of an abnormality rather than a variation within normal limits in genes. Dwarfism is an abnormally small body structure, often with skeletal deformity and altered body proportions. Dwarfism can result from abnormalities of the pituitary gland or from genetic mutations. Pituitary dwarfism is the result of inadequate production of growth hormone (GH) by the pituitary gland. This lack of production can be caused by any of the following:
Dogs appear normal at birth but usually show evidence of failure to grow by two to three months of age. Pituitary dwarf dogs often have normal proportionate sizes to their body structures, they are simply smaller than expected, but may be unable to progress mentally as well as physically. It is an inherited disease in German shepherds (autosomal recessive trait). This disorder must be distinguished from other conditions leading to stunted growth, including malnutrition, congenital hypothyroidism and other congenital defects leading to poor growth. Dogs with this condition do not grow like their littermates. Their hair retains its "puppy" appearance, feeling soft to the touch. Hairloss along the sides that is symmetrical often occurs. Abnormalities in bone growth lead to a deformed appearance to the legs. As other puppies in the litter appear to mature, affected dogs continue to have a puppy-like appearance and bark. Dogs with this condition may be deficient in other hormones in which the pituitary gland controls part of the process of stimulating the hormone's production. It is a good idea to check for hypothyroidism and hypoadrenocorticism in dogs with hyposomatotrophism. There are no effective treatments for pituitary dwarfism dogs. Although human growth hormones have been tried, the cost is very high and the results have shown only limited degrees of success. Because so many organs are affected by a lack of growth hormone, normal life spans are not expected. Pituitary dwarfism is not common, but has occurred in many breeds ie: Alaskan Malamute, Australian Shepherd, Collie, GSD, Giant Schnauzer, Labrador Retriever, Samoyed, Shih Tzu, and Weimaraner. Genetic dwarfismThrough the centuries, people have selectively bred dogs to retain certain genetic defects or mutations. There are many breeds of dwarf dogs where the characteristics of dwarfism are part of the breed standard. (The name Corgi literally means “dwarf dog” in Welsh.) There are three primary types of genetic dwarfism: chondrodystrophic, achondroplastic and brachiocephalic. Some breeds may exhibit characteristics of more than one kind of dwarfism, for example the Bulldog is both an achondroplastic and a brachiocephalic dwarf. Chondrodystrophic is the abnormal cartilage growth resulting in shortened legs Associated health problems are intervertebral disk disease (IVDD), Osteochondritis Dissecans (OCD), hip dysplasia , vertebral malformations, disk herniation, spina bifida, reproductive problems . PreventionKeeping a dwarf breed dog at optimum weight is one of the best preventative measures as being overweight puts stress on vertebrae, leg bones and joints, and even more important for brachiocephalic dogs, heart and lungs. Because their nasal passages are smaller, making it more difficult to circulate sufficient air for cooling, brachiocephalic dogs are more prone to heat discomfort and heat stroke. Keep cool water readily available and take all necessary steps to prevent overheating. Breeds commonly associated with achondroplastic dwarfism are basset hounds, dachshunds, shih-tzus, pekingese, sharpeis and English and French bulldogs. These dog always have limbs that are shorter than their body and often have over-large heads as well. |