Overview
Part of the official UK Kennel Club testing scheme in Tibetan Terrier
Pituitary dwarfism in dogs is a congenital condition caused by a deficiency of growth hormone. Dogs affected by this condition have underdeveloped pituitary glands, which leads to a lack of multiple hormones necessary for proper growth and development. Although affected dogs appear normal at birth, they begin to show signs of growth failure around two to three months of age and never reach their normal adult size. In addition to growth deficiencies, these dogs exhibit distinct characteristics such as retaining their soft, puppy-like coat and a failure to grow primary guard hairs. They often experience various skin abnormalities like scaling, bacterial skin infections, and hyperpigmentation. By the time they reach 3 to 5 years of age, affected dogs may develop severe hair loss on their trunk, neck, and limbs (alopecia) and may also suffer from complications including mental dullness and kidney disease. If left untreated, affected dogs typically have a significantly shortened lifespan and may die or need to be euthanized by the age of 5 due to concerns about their quality of life.
If left untreated, their lifespan is significantly shortened and dogs are often euthanised.
The 7 bp deletion in the gene called LHX3 that causes Pituitary Dwarfism in Tibetan Terrier and German Shepherd is autosomal recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop Pituitary dwarfism during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop Pituitary dwarfism as a result of the LHX3 mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop Pituitary dwarfism should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the LHX3 mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Pituitary Dwarfism, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.
