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Also Known As – '''''Parathyroid hyperplasia – Parathyroid adenoma - Fibrous Osteodystrophy – Grain Overload – Bran Disease – Big Head Disease – Millers Disease - Rubber Jaw '''''
Also Known As – '''''Parathyroid hyperplasia – Parathyroid adenoma - Fibrous Osteodystrophy – Grain Overload – Bran Disease – Big Head Disease – Millers Disease - Rubber Jaw – Metabolic Bone Disease'''''
==Introduction==
==Introduction==
[[Image:parathyroidadeoma.jpg|thumb|right|200px|Parathyroid adenoma. Image courtesy of Biomed Archive.]]
[[Image:parathyroidhyperplasia.jpg|thumb|right|200px|Parathyroid hyperplasia. Image courtesy of Biomed Archive.]]
[[Image:secondaryhyperparathyroidism.jpg|thumb|right|200px|Secondary hyperparathyroidism - "rubber jaw". Image courtesy of Biomed Archive.]]
[[Image:renalhyperparathyroidism.jpg|thumb|right|200px|Parathyroid hyperplasia in renal hyperparathyroidism. Image courtesy of Biomed Archive.]]
[[Image:Renal_osteodystrophy.jpg|thumb|right|200px|"Rubber jaw" in renal osteodystrophy. Image courtesy of Biomed Archive.]]
[[Image:Renal osteodystrophy.jpg|right|thumb|200px|Renal osteodystrophy (Image sourced from Bristol Biomed Image Archive with permission)]]
Hyperparathyroidism is an [[Endocrine System - Anatomy & Physiology|endocrine]] disease caused by overactivity of the [[Parathyroid Glands - Anatomy & Physiology|parathyroid gland]] and consequent raised body levels of [[Calcium#Parathyroid Hormone|parathyroid hormone (PTH)]]. It occurs in many veterinary species and can be primary or secondary.
Hyperparathyroidism is an [[Endocrine System - Anatomy & Physiology|endocrine]] disease caused by overactivity of the [[Parathyroid Glands - Anatomy & Physiology|parathyroid gland]] and consequent raised body levels of [[Calcium#Parathyroid Hormone|parathyroid hormone (PTH)]]. It occurs in many veterinary species and can be primary or secondary.
Secondary renal hyperparathyroidism is seen frequently in dogs and occasionally in cats.
Secondary renal hyperparathyroidism is seen frequently in dogs and occasionally in cats.
Nutritional secondary HPT can affect horses of all breeds and ages that are either supplemented with large amounts of grain based concentrates or bran, or those that escape and break into a grain store or similar.
Nutritional secondary HPT can affect horses of all breeds and ages that are either supplemented with large amounts of grain based concentrates or bran, or those that escape and break into a grain store or similar. It is also seen occasionally in dogs and cats fed all meat diets and pigs fed unsupplemented cereal feed. It is most commonly seen in young growing animals.
Metabolic Bone Disease occurs in a wide range of reptiles.
Metabolic Bone Disease occurs in a wide range of captive reptiles, particularly young green iguanas.
Any disease in ruminants is very rare and usually mild.
==Clinical Signs==
==Clinical Signs==
Sequelae of hyperparathyroidism include fibrous osteodystrophy and
Sequelae of hyperparathyroidism include fibrous osteodystrophy and
Osteodystrophy is the [[Bones - Anatomy & Physiology#Osteoclasts|osteoclastic resorption]] of bone and replacement by weaker fibrous tissue. When this occurs in the long bones it causes shifting lameness and weakened bones that are prone to [[Fractures|fracture]]. Compression fractures may also occur spontaneously and if this occurs in the vertebrae, nerve dysfunction results.<ref>Merck Veterinary Manual, '''Metabolic Osteodystrophies: Fibrous Osteodystrophy: Primary Hyperparathyroidism''', accessed online 25/07/2011 at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/90313.htm</ref>
Osteodystrophy is the [[Bones - Anatomy & Physiology#Cells|osteoclastic resorption]] of bone and replacement by weaker fibrous tissue. When this occurs in the long bones it causes shifting lameness and weakened bones that are prone to [[Fractures|fracture]]. Compression fractures may also occur spontaneously and if this occurs in the vertebrae, nerve dysfunction results.<ref>Merck Veterinary Manual, '''Metabolic Osteodystrophies: Fibrous Osteodystrophy: Primary Hyperparathyroidism''', accessed online 25/07/2011 at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/90313.htm</ref> Weakened bones may also cause tendon and ligament avulsions.
Fibrous osteodystrophy in the flat bones of the skull and face causes facial hyperostosis. This is seen in Bran disease or grain overload in horses and also in dogs with primary hyperparathyroidism. The face and head become grossly disfigured by excessive amounts of fibrous tissue laid down in an attempt to consolidate the weakened lamellar bone. In advanced cases, the mandible may become pliant and teeth may loosen, hence the colloquial name, “rubber jaw”. This may interfere with mastication and cause pain, dysphagia and consequent weight loss.
Fibrous osteodystrophy in the flat bones of the skull and face causes facial hyperostosis. This is seen in Bran disease or grain overload in horses and also in dogs with primary hyperparathyroidism. The face and head become grossly disfigured by excessive amounts of fibrous tissue laid down in an attempt to consolidate the weakened lamellar bone. In advanced cases, the mandible may become pliant and [[Teeth - Anatomy & Physiology|teeth]] may loosen, hence the colloquial name, “rubber jaw”. This may interfere with mastication and cause pain, dysphagia and consequent weight loss.
Animals affected by secondary renal HPT may exhibit classical signs of renal insufficiency such as polydipsia, polyuria, weight loss, vomiting and dehydration.
Animals affected by secondary renal HPT may exhibit classical signs of renal insufficiency such as polydipsia, polyuria, weight loss, vomiting and dehydration.
[[Metabolic Bone Disease]] in reptiles is caused by inadequate UVB light which diminishes Vitamin D production in the skin. Affected animals often have limb deformities, pathological fractures, are lethargic, very weak and inappetant and may also show signs of concurrent [[Hypocalcaemia|hypocalcaemia]]. They may also exhibit [[Dysecdysis|dysecdysis]].
==Diagnosis==
==Diagnosis==
In cases of nutritional hyperparathyroidism, serum calcium is normal or low compared to high in other pathogeneses. Urinary excretion of phosphorus is markedly increased and serum PTH high. Radiographs will identify bony resorption and pathological fractures with fibrous tissue calluses.
In cases of nutritional hyperparathyroidism, serum calcium is normal or low compared to high in other pathogeneses. Urinary excretion of phosphorus is markedly increased and serum PTH high. Radiographs will identify bony resorption and pathological fractures with fibrous tissue calluses.
MBD is usually identified by clinical signs and radiographic evidence of a poorly mineralised skeleton.
==Treatment==
==Treatment==
Treatment for primary hyperparathyroidism usually required surgical excision. Hypocalcaemia is a known post-operative complication and supplementation may be required in the short or long term management. If the hypercalcaemia persists, metastatic disease should be suspected and investigated.
Treatment for primary hyperparathyroidism usually required surgical excision. Hypocalcaemia is a known post-operative complication and supplementation may be required in the short or long term management. If the hypercalcaemia persists, metastatic disease should be suspected and investigated.
Merck Vet Manual, Nutritional Diseases, accessed 25/07/2011 at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/182606.htm&word=nutritional%2csecondary
Merck Vet Manual, Nutritional Diseases, accessed 25/07/2011 at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/182606.htm&word=nutritional%2csecondary
[[Category:To Do - Manson review]] [[Category: Endocrine Diseases - Horse]] [[Category: Endocrine Diseases - Dog]] [[Category: Endocrine Diseases - Cat]] [[Category: Endocrine Diseases - Reptile]]
[[Category:To Do - Manson review]] [[Category: Endocrine Diseases - Horse]] [[Category: Endocrine Diseases - Dog]] [[Category: Endocrine Diseases - Cat]] [[Category: Endocrine Diseases - Reptile]] [[Category:Bones - Metabolic Pathology]] [[Category:Parathyroid Glands - Pathology]]