isoform. As pentosan polysulfate can bind to the cellular isoform of the prion protein, it may stabilise this form and prevent its conversion to the pathological (scrapie) isoform. The treatment of one patient in Northern Ireland and around six other patients in mainland Britain was reported in the press. Veterinary uses Dogs Read et al. (1996) used three different doses of sodium pentosan polysulfate to treat 40 geriatric dogs with well-established clinical signs of chronic osteoarthritis (OA) with a subcutaneous injection. The 3 mg/kg dose was the most effective. In a study conducted with 10 elderly dogs with osteoarthritis given calcium pentosan polysulfate (3 mg/kg intramuscularly) once weekly for four weeks, the improvement in symptoms (seen at 1, 2, 3 and 7 weeks after initiation of therapy) was found to correlate with plasma indices of fibrinolytic activity and lipid profiles. In a study in dogs with OA secondary to cranial cruciate ligament deficiency, although no differences were identified in either functional outcome or radiographic progression using the oral calcium pentosan polysulfate compared with placebo, there were significantly lower levels of proteoglycan breakdown products in the synovial fluid of the osteoarthritic joints. The efficacy of subcutaneous sodium pentosan polysulfate (3 mg/kg) was tested in 40 dogs with cranial cruciate ligament instability and found to hasten recovery, as measured by more rapidly improved ground reaction forces, over 48 weeks. Horses In December 2022, the US Food and Drug Administration (FDA) approved pentosan polysulfate (Zycosan) for the control of clinical signs associated with osteoarthritis in horses. Zycosan is for intramuscular use in horses only and is not for use in humans. Zycosan is sponsored by Anzac Animal Health LLC, based in Maryland Heights, Missouri. Pentosan polysulfate is being used for this osteoarthritis in Australia. When administered to racing thoroughbreds with chronic osteoarthritis (2 to 3 mg/kg, intramuscularly, once weekly for 4 weeks, then as required), pentosan polysulfate treatment improved but did not eliminate clinical signs of joint disease. Articular cartilage fibrillation was substantially reduced by similar NaPPS treatment intramuscularly in nine horses with experimentally-induced carpal osteoarthritis. References External links Drugs acting on the musculoskeletal system Urologic pelvic pain syndrome IARC Group 2B carcinogens