acidic. Such stones can create irritation and infection of the urinary tract and require veterinary treatment. Organizations that advocate vegan or vegetarian diets for people have split opinions regarding vegetarian or vegan cat food. The International Vegetarian Union, the Vegan Society and PETA are some of the organizations that support a vegan or vegetarian diet for cats. But the Vegetarian Society suggests people "consider carefully" and that many cats will not adjust to a vegetarian diet. The Animal Protection Institute also does not recommend a vegetarian diet for cats, and cautions that dietary deficiencies may take months or years to develop and may be untreatable. They do not recommend relying on supplements, because they may not contain necessary co-factors and enzymes and have not been studied for long term implications. The animal welfare organization American Society for the Prevention of Cruelty to Animals, although suggesting a supplemented vegetarian diet for dogs, recommends against vegetarian and vegan diets for cats. The Association of Veterinarians for Animal Rights (now Humane Society Veterinary Medical Association) accepts that a plant-based diet can be nutritionally adequate, but stated in August 2006 that such diets "cannot at this time be reliably assured". Homemade Many pet owners feed cats homemade diets. These diets generally consist of some form of cooked or raw meat, bone, vegetables, and supplements, such as taurine and multivitamins. Homemade diets either follow a recipe, such as the BARF (bone and raw food) diet which provides a series of options for the pet owner to make, or rely on the constant rotation of ingredients to meet nutrient requirements. A study was conducted that analyzed 95 homemade BARF diets and found that 60% of these were nutritionally imbalanced in either one or a combination of calcium, phosphorus, vitamin D, iodine, zinc, copper, or vitamin A content. Another 2019 study on a range of homemade diet recipes found online and in books has also found nutritional inadequacies. The authors mention that vegetarianism and support for organics food are common reasons for trying such a diet, but does not specifically address the adequacy of vegetarian or organic diets. Nutrients and supplements Vitamin deficiencies can lead to wide-ranging clinical abnormalities that reflect the diversity of their metabolic roles. Twelve minerals are known to be essential nutrients for cats. Calcium and phosphorus are crucial to strong bones and teeth. Cats need other minerals, such as magnesium, potassium, and sodium,