Cats suffer from many of the same age-related diseases we do, including osteoporosis. Osteoporosis is defined as a reduction of bone mass while the bone volume remains the same. Osteoporosis most often results from excessive removal of bone into the bloodstream or a diet deficient in key bone building nutrients.
Osteoporosis can develop when a cat doesn't get enough calcium in her diet. Cats need calcium, phosphorus and magnesium to keep bones strong and healthy. When a cat doesn't eat enough calcium, the body takes calcium from bones to use in other bodily processes. Hyperphosphatemia, which results from a diet too high in phosphorous and/or too low in calcium, can also cause osteoporosis. A lack of vitamin D, which is essential for synthesizing calcium, is another cause. Low vitamin D is a greater risk for indoor cats who spend little time exposed to the sun.
Possible Causes -- Reduced Estrogen Production
Researchers Liang H, S Pun, and TJ Wronski, University of Florida College of Veterinary Medicine, conducted studies on rats in 1999 which showed that much like human females going through menopause, rats could develop osteoporosis as a direct result of reduced estrogen production. To test their hypothesis they removed the ovaries from reproductive-aged rats. Based on these findings, it is possible for female cats to develop osteoporosis when they live past their reproductive years.
Possible Causes -- Hyperparathyroidism
Hyperparathyroidism, a possible cause of osteoporosis, is a condition in which the parathyroid gland releases too much parathyroid hormone into the cat's system. Parathyroid controls the amount of calcium, phosphorus, and vitamin D levels in the blood and bone. The most common reason this disease develops is when one of the two hyperparathyroid glands grows larger. It then excretes more parathyroid hormone, which causes calcium to be taken into the bloodstream from bone tissue. Kidney failure is another possible cause. Symptoms of hyperparathyroidism include weak bones, feeling tired or weak, kidney stones, nausea and loss of appetite. A veterinarian can diagnose hyperparathyroidism through blood tests and x-rays. Treatment may include encouraging your cat to drink more fluids, increasing calcium and vitamin D while avoiding phosphate in her diet, or in some cases, surgery.
Signs and Symptoms
Osteoporosis often goes unnoticed in pets until a bone breaks. If your cat seems to be suffering from pain in her back and appears weak these could be signs of osteoporosis. Bone breaks in the tail can happen easily in a cat with osteoporosis. Signs of a break include dragging the tail or the tail bent at an awkward angle. If your cat seems to have a broken tail take her to your vet immediately, and ask if osteoporosis could have been the cause for the fracture.
It is possible to reverse the damage caused by osteoporosis if the cause of the disease, whether it be hormonal, dietary, or otherwise, is reconciled. The best form of treatment for dietary osteoporosis is to increase the cat's calcium intake. Ask your veterinarian for advice before administering any dietary supplements to your pet. Calcium for cats can be purchased as tablets. Animal grade bonemeal powder or ground eggshells can also serve as natural dietary supplements to increase your cat's calcium intake.
- European Cells and Materials Vol. 1. 2001 (pages 66-81): Animal Models of Osteoporosis -- Necessity and Limitations, Turner, Simon A.
- Osteoporosis and Osteopetrosis: Chapter 55, Fetter, Arthur W., Siemering, George H., Riser, Wayne H.
- UF Physiological Sciences College of Veterinary Medicine: Bone & Osteoporosis
- Clinicopathologic Principles for Veterinary Medicine: edited by Robinson, Wayne F., Huxtable, Clive R. R. p 314
- petMD: Geriatric Pets Need More Protein
- PubMed Health: Hyperparathyroidism
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