the breed tend to be immunity related. They can be affected by eye problems and hip dysplasia and are predisposed to immune-mediated rheumatic disease and steroid-responsive meningitis–arthritis. Progressive retinal atrophy (PRA) affects about 7% of Tollers with an estimated 40% being carriers. The type of PRA associated with the breed is known as progressive rod-cone degeneration. The disease causes cells in the retina to degenerate and die. This causes night blindness at first and eventually complete blindness. Collie eye anomaly is estimated to have a carrier rate of 5% and an affected rate of 0.5%. It generally only causes mildly impaired vision, although in more severe cases it can lead to retinal hemorrhaging and detachments resulting in blindness. Thyroid problems have been identified by American breeders as a priority issue, together with epilepsy and hip dysplasia. As many as 1 in 6 Tollers may have autoimmune thyroiditis. Symptoms of thyroid problems includes weight gain, skin and hair problems including hair loss, weakness, cold intolerance or infertility. Addison's disease affected 1% of Tollers in a health survey, an incidence rate 10 times more than the general dog population. Carrier rate is estimated at 18%. This disease is also considered an important issue in the breed. Signs include lethargy, decreased appetite, vomiting, weakness, diarrhea, increased drinking and urination, and shivering. Aseptic meningitis (sometimes called steroid-responsive meningitis) has been diagnosed in increasing numbers in the Norwegian Toller population in recent years. Symptoms include intensive neck pain, fever, and lethargy. Prevalence is estimated at 2.5% in the Norwegian population. Health tests are available for both eye diseases and autoimmune thyroiditis. A test for Addison's disease is available but it is only for one form of the disease and there are other forms which also affect the breed. A test is also available for one form of cleft palate that is exclusive to Tollers. Early testing shows a carrier rate of about 15%. A survey conducted in 2002 by the Canadian Nova Scotia Duck Tolling Retriever breed club to discover which diseases and conditions occur in the Toller population, involving owners of 1180 dogs worldwide, showed 73% reported in excellent health and a total of 7.5% reporting poor or bad health. 141 dogs (12%) were reported as deceased with the average age at death being 6.4 years. The most common cause of death was cancer, reported in 25% of deaths, with old age being the