The parathyroids are 4 small glands in the neck located near the thyroid gland. The parathyroid glands secrete the hormone PTH, which is essential to bone metabolism and blood calcium regulation.
Signs of primary Hyperparathyroidism are non-specific and include loss-of-appetite, lethargy, excessive thirst, and frequent urination. Constipation, weakness, vomiting, muscle twitching, and a stiff gait have all been reported. The disease may not be suspected until a chemistry panel reveals a high serum calcium.
Symptoms of Renal Secondary Hyperparathyroidism are similar to those of primary hyperparathyroidism are usually overshadowed by the kidney problem.
In puppies and young dogs with nutritional secondary hyperparathyroidism, signs suggest skeletal problems and include lameness, bone pain, stunted growth, and spontaneous fractures. In adult dogs, nutritional secondary hyperparathyroidism produces periodontal disease. Thinning of the jaws exposes the roots of the teeth. The teeth then loosen and fall out.
This disease is rare in dogs. It is caused by tumors of the parathyroid glands that cause them to secrete excessive amounts of PTH. Middle-aged and older dogs are affected. The average age of onset is 10. Keeshonds seem to have a breed predisposition to this problem.
A primary parathyroid hyperplasia syndrome, in which all four parathyroid glands are enlarged, has been identified in German Shepherd puppies. This is an inherited autosomal recessive trait.
Anal sac adenocarcinomas have the unique property of producing PTH, and thus are a rare cause of pseudohyperparathyroidism.
Renal Secondary Hyperparathyroidism
This is the end result of long-standing kidney disease that causes the body to retain phosphorus. The high serum phosphorus and low serum calcium stimulates the parathyroids to produce PTH.
Nutritional Secondary Hyperparathyroidism
This disease (which is now rare) is caused by an excess of phosphorus or a deficiency of calcium in the diet. Vitamin D is required for calcium to be absorbed from the small intestine. So, a deficiency of vitamin D produces a deficency of calcium. This can cause the parathyroid glands to produce more PTH.
One cause of nutritional secondary hyperparathyroidism is feeding a diet that consists primarily of organ meats, such as hearts, livers, or kidneys. Such diets are too high in phosphorus and too low in calcium and vitamin D. Other diets low in calcium are all-vegetable diets, corn bread diets, and diets containing left over table scraps. This disease does not occur in dogs who eat a nutritionally balanced diet.
The diagnosis of primary hyperparathyroidism can be confirmed by measuring PTH. The serum PTH is above normal in dogs with this disease.
With primary hyperparathyroidism, the only possible treatment is the surgical removal of the affected glands.
Treatment for Renal Secondary Hyperparathyroidism is directed toward correcting the kidney disease.
Treatment for nutritional secondary hyperparathyroidism includes correcting the diet by feeding high quality foods - and in the case of puppies, one that is designed to support growth. Vitamin and mineral supplements should not be given unless prescribed by a veterinarian.
Affected puppies should be kept quiet and confined for the first few weeks to prevent fractures. Older dogs with advanced periodontal disease or intractable eating habits may not eat enough of their balanced food. These dogs need restorative dentistry and may require dietary supplements.
Please contact your veterinarian if you think your pet may have this condition.
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