Pre-operative fibrous osteodystrophy and severe, refractory, post-operative hypocalcemia following parathyroidectomy in a dog

A 13-year-old dog exhibited dramatic, radiographic osteopenia consistent with fibrous osteodystrophy secondary to primary hyperparathyroidism. Following parathyroidectomy, the dog developed severe, prolonged hypocalcemia, but was successfully treated and discharged 32 d after surgery. A variety of factors may have contributed to this dog's hypocalcemia including hypoparathyroidism and hungry bone syndrome.

Functional metastatic parathyroid adenocarcinoma in a dog

A 12-year-old dachshund dog was presented for persistent hypercalcemia and hyperparathyroidism despite bilateral parathyroidectomy. Magnetic resonance imaging of the head, neck, and cranial mediastinum identified an increased number of cranial mediastinal lymph nodes with heterogeneous signal intensity. Hypercalcemia and hyperparathyroidism resolved after surgery to remove multiple cranial mediastinal lymph nodes, one of which contained presumed metastatic parathyroid tissue.

Hyperthyroidism and hyperparathyroidism in guinea pigs (Cavia porcellus)

Abnormal conditions of the thyroid and parathyroid in the guinea pig appear in the English-language scientific literature on an emerging basis. Although true descriptions of abnormal thyroid and parathyroid anatomy or morphology are not new findings, the clinical condition of abnormal thyroid or parathyroid function seems to be a more common observation by clinicians in recent years. This article is an overview of general clinical conditions and adequate diagnosis, and offers treatment options.

Metabolic complications of endocrine surgery in companion animals

Metabolic complications of endocrine surgery occur commonly and precautions should be taken to avoid potentially life-threatening situations and to lessen expense associated with a more extended hospital stay. Common complications of endocrine surgery as well as prevention strategies will be reviewed for pancreatic, parathyroid, and adrenal surgery.

Mutations in genes causing human familial isolated hyperparathyroidism do not account for hyperparathyroidism in Keeshond dogs

The roles of the calcium sensing receptor gene (CaSR) and the multiple endocrine neoplasia gene (MEN1) were investigated in Keeshond dogs with familial hyperparathyroidism. Mutations in these genes have been shown to cause familial isolated hyperparathyroidism (FIH) in humans. Affected dogs were identified through measurement of blood calcium and parathyroid hormone levels. Parathyroid tissue and whole blood was used to clone the cDNAs and individual exonic sequences of both candidate genes. No sequence abnormalities were identified when comparing normal and affected dogs, suggesting that a mapping strategy may be the most appropriate approach for identifying the genetic basis of this valuable comparative canine disease model.

Inheritance, mode of inheritance, and candidate genes for primary hyperparathyroidism in Keeshonden

BACKGROUND

Primary hyperparathyroidism (PHPT) is caused by inappropriate secretion of parathyroid hormone (PTH) by autonomously functioning neoplastic or hyperplastic parathyroid "chief" cells. Keeshonden are thought to be over-represented in studies on canine PHPT, but no proof of heritability or mode of inheritance has been published. The canine disease clinically resembles human familial isolated hyperparathyroidism (FIHP).

HYPOTHESIS

Primary hyperparathyroidism in Keeshonden is genetically transmitted and is caused by a mutation in 1 of 4 genes implicated in human FIHP: MEN1, CASR, HRPT2, or RET.

ANIMALS

Pedigrees consisting of 1647 Keeshonden were created including 219 Keeshonden with known PHPT phenotypes (69 positive). DNA samples were obtained from 176 of the 219 Keeshonden (34 positive).

METHODS

Heritability and mode of inheritance were determined by segregation analysis. Canine homologs to the human genes were identified. Exons and surrounding intron regions were sequenced and scanned for sense-altering polymorphisms or polymorphisms that segregated with the disease. Messenger RNA from a parathyroid tumor of an affected Keeshond was analyzed for polymorphisms and splice alterations.

RESULTS

PHPT follows an autosomal dominant mode of inheritance in Keeshonden with possible age-dependent penetrance. No polymorphisms identified in the genes analyzed were associated with a change in predicted protein or in hypothesized splice sites.

CONCLUSIONS AND CLINICAL IMPORTANCE

PHPT is an autosomal dominant, genetically transmitted disease in Keeshonden. Once the mutation locus is identified, genetic testing should quickly decrease the incidence of PHPT in this breed. It is unlikely that mutations in MEN1, CASR, HRPT2, or RET cause PHPT in Keeshonden.

Plasma concentrations of parathyroid hormone-related protein in dogs with potential disorders of calcium metabolism

The plasma concentrations of total calcium, ionised calcium, albumin, parathyroid hormone and parathyroid hormone-related protein (PTHrp) were measured in 25 dogs with lymphoma, nine dogs with primary hyperparathyroidism and seven dogs with adenocarcinoma of the apocrine gland of the anal sac. Plasma total calcium, ionised calcium, albumin and parathyroid hormone-related protein were measured in 18 clinically normal control dogs. The concentration of PTHrp was high in 12 of the 14 dogs that were hypercalcaemic because of an underlying malignancy but was within the reference range in all the control dogs, in the 17 normocalcaemic dogs with lymphoma and in the seven dogs which were hypercalcaemic because of a parathyroid adenoma.

Primary hyperparathyroidism in 29 dogs: diagnosis, treatment, outcome and associated renal failure

OBJECTIVES

To review the records of 29 dogs diagnosed with primary hyperparathyroidism and see if any factors correlate with renal failure.

METHODS

Dogs were selected retrospectively from case files from the QVSH and the QMH.

RESULTS

The majority of dogs were middle-aged and four were keeshonds. The primary presenting complaints were polyuria and polydipsia. All dogs had an elevated total and ionised plasma calcium concentration. Plasma phosphate concentrations were variable. Ultrasonography of the parathyroid gland revealed nodular enlargement which was found to correlate well with surgical findings. The majority of dogs underwent surgical parathyroidectomy. Five cases were treated by ultrasound-guided chemical ablation of the parathyroid gland, of which only two cases showed a partial response. Three dogs were euthanased within a week of presentation. Seven other dogs had renal failure diagnosed either at presentation or up to six months after parathyroidectomy. The development of renal failure was correlated with total calcium concentration but did not correlate with any other factor, including the calcium phosphate product. Thirteen treated dogs were known to be alive at the time of writing, which was six months to 3.5 years after parathyroidectomy.

CLINICAL SIGNIFICANCE

Primary hyperparathyroidism cases with high total calcium were more likely to develop renal failure in this group of dogs; however, the calcium phosphate product did not seem to be a useful predictor. Ultrasound-guided chemical ablation seemed to have limited advantage over surgery.

Pretreatment clinical and laboratory findings in dogs with primary hyperparathyroidism: 210 cases (1987–2004)

OBJECTIVE

To evaluate pretreatment clinical and laboratory findings in dogs with naturally occurring primary hyperparathyroidism.

DESIGN

Retrospective study.

ANIMALS

210 dogs with primary hyperparathyroidism and 200 randomly selected, age-matched control dogs that did not have primary hyperparathyroidism.

PROCEDURE

Medical records for dogs with primary hyperparathyroidism were reviewed for signalment; clinical features; and results of clinicopathologic testing, serum parathyroid hormone assays, and diagnostic imaging.

RESULTS

Mean age of the dogs with primary hyperparathyroidism was 11.2 years (range, 6 to 17 years). The most common clinical signs were attributable to urolithiasis or urinary tract infection (ie, straining to urinate, increased frequency of urination, and hematuria). Most dogs (149 [71%]) did not have any observable abnormalities on physical examination. All dogs had hypercalcemia, and most (136 [65%]) had hypophosphatemia. Overall, 200 of the 210 (95%) dogs had BUN and serum creatinine concentrations within or less than the reference range, and serum parathyroid hormone concentration was within reference limits in 135 of 185 (73%) dogs in which it was measured. Urolithiasis was identified in 65 (31 %) dogs, and urinary tract infection was diagnosed in 61 (29%). Mean serum total calcium concentration for the control dogs-was significantly lower than mean concentration for the dogs with primary hyperparathyroidism, but mean BUN and serum creatinine concentrations for the control dogs were both significantly higher than concentrations for the dogs with primary hyperparathyroidism.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that urolithiasis and urinary tract infection may be associated with hypercalcemia in dogs-with primary hyperparathyroidism, but that development of renal insufficiency is uncommon.

NATURALLY OCCURRING SECONDARY NUTRITIONAL HYPERPARATHYROIDISM IN CATTLE EGRETS (BUBULCUS IBIS) FROM CENTRAL TEXAS

Naturally occurring secondary nutritional hyperparathyroidism is described in the nestlings of two colonies of cattle egrets (Bubulcus ibis) from Central Texas (Bryan and San Antonio, Texas, USA). Nestlings from a third colony (Waco, Texas, USA) were collected in a subsequent year for comparison. Birds from the first two colonies consistently had severe osteopenia and associated curving deformities and folding fractures of their long bones. These birds also had reduced bone ash, increased osteoclasia, a marked decrease in osteoblast activity, variable lengthening and shortening of the hypertrophic zone of the epiphyseal cartilage, decreased and disorganized formation of new bone, and a marked hypertrophy and hyperplasia of the parathyroid glands as compared to birds collected from the third colony. Fibrous osteodystrophy was found in all of the birds from San Antonio and Bryan. Evidence of moderate to severe calcium deficiency was also identified in 33% of the cattle egrets collected from Waco. Gut contents of affected chicks contained predominately grasshoppers and crickets; vertebrate prey items were absent from the Bryan birds. Grasshoppers and crickets collected from fields frequented by the adult egrets in 1994 had 0.12-0.28% calcium and 0.76-0.81% phosphorus. Pooled grasshoppers and crickets collected during a subsequent wet early spring averaged 0.24% calcium and 0.65% phosphorus. Although the phosphorus content of the insect prey was adequate for growth, calcium was approximately one-third the minimum calcium requirement needed for growth for other species of birds. It was postulated that cattle egrets breeding in Central Texas have expanded their range into habitat that contains less vertebrate prey, and as a result, many nestling egrets are being fed diets that contain suboptimal calcium. Therefore, in years where vertebrate prey is scarce and forage for insect prey is reduced in calcium, nestling egrets are at risk for developing secondary nutritional hyperparathyroidism.

Serum levels of 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol in dogs with hypercalcaemia

1,25-Dihydroxycholecalciferol (1,25-(OH)2-D3) and 25-hydroxycholecalciferol (25-OH-D3) were measured among dogs with hypercalcaemia (total serum calcium > 3.01 mmol/L) due to various causes. All values were compared to those of healthy control dogs. Serum 1,25-(OH)]2-D3 was measured by a radioimmunoassay test and serum 25-OH-D3 was measured by a protein binding assay. 1,25-(OH)2-D3 ranged from 26 to 332 pmol/L (median 110.0) in dogs with lymphoma (n = 12); from 61 to 398 pmol/L (median 248.0) in dogs with primary hyperparathyreoidism (n = 5); from 28 to 310 pmol/L (median 88.5) in dogs with chronic renal failure (n = 10); and from 60 to 239 pmol/L (median 157.5) in control dogs (n = 24). There was no significant difference in 1,25-(OH)2-D3 among dogs with different causes of hypercalcaemia. 25-OH-D3 ranged from 64 to 291 nmol/L (median 101.5) in dogs with lymphoma; from 66 to 298 nmol/L (median 91.0) in dogs with primary hyperparathyreoidism; from 35 to 184 nmol/L (median 67.0) in dogs with chronic renal failure; and from 48 to 350 nmol/L (median 306.5) in control dogs. 25-OH-D3 was significantly lower in dogs with lymphoma, primary hyperparathyroidism and chronic renal failure than in control dogs. 1,25-(OH)2-D3 and 25-OH-D3 are not predictable in dogs with hypercalcaemia.

Feline endocrinopathies

Feline endocrinopathies (excluding diabetes mellitus) include hyperthyroidism, hypothyroidism, acromegaly, hyposomatotropism, diabetes insipidus, hyperadrenocorticism, primary sex hormone-secreting adrenal tumors, primary hyperaldosteronism, pheochromocytoma, hypoadrenocorticism, hyperparathyroidism, and hypoparathyroidism. Each of these conditions will be discussed including their prevalence, cause, clinical signs, diagnosis, treatment options, and prognosis.

Renal handling of calcium and phosphorus in experimental renal hyperparathyroidism in dogs

Twenty-four hour urinary excretion, fractional excretion and the filtered load of calcium and phosphorus were monitored as hyperparathyroidism evolved in a model of progressive canine renal failure. Thirteen beagles of both sexes aged four and a half months were used. Nine of them were subjected to a renal damaging schedule (neomycine, 60 mg/kg/48 h, IM, 32 weeks) in order to induce chronic renal failure leading to secondary hyperparathyroidism (2HPT group). The remaining four were kept as the control group. The experiment was conducted over 32 weeks. Blood and 24 h urine were collected every four weeks. Calcium, phosphorus and creatinine were analyzed. Plasma parathormone and calcitonin were determined at weeks 0, 12, 24 and 32. The level of renal function in the 2HPT animals was reduced to 25% of that of the controls (endogenous creatinine clearance was 0.45 +/- 0.22 mL/min/kg as opposed to 1.81 +/- 0.54 mL/min/kg). Hyperparathyroidism was confirmed by a progressive increase in the levels of the parathyroid hormone. Calcitonin levels were not modified. A tendency to hypocalcaemia was observed, reaching statistically significant levels from the twenty-eighth week of the study, when hyperphosphataemia also became significant. Daily urinary excretion of calcium and phosphorus remained at values considered normal throughout the experiment with no alteration imputable to the impaired renal function. This is explained by the decrease in the filtered load of these elements (in both cases statistically significant from the 24th week on) being associated with an increase in their fractional excretion. Thus, calcium and phosphorus urinary excretion values could be maintained in a normal range up to the end of the experiment, showing that renal calcium handling in dogs with experimentally induced renal failure seems to differ from that observed in human patients.

Primary hyperparathyroidism in an adult female olive baboon (Papio anubis)

During an annual physical examination, a middle-aged adult female olive baboon (Papio anubis) in the time-mated breeding colony at the Biologic Resources Laboratory at the University of Illinois at Chicago was found to have a high serum calcium value (> 12 mg/dl). To determine the cause of the hypercalcemia, additional diagnostic tests, including thoracic and abdominal radiographs and a parathyroid panel (parathyroid hormone (PTH), ionized calcium, and parathyroid hormone-related protein (PTH-rp) assays), were performed. The radiographs did not reveal lesions suggestive of neoplasia. A parathyroid panel was obtained twice. Both times the PTH (23.4 and 46.4 pmol/L, normal = 2.91 to 4.57 pmol/L) and ionized calcium (1.68 and 2.10 mmol/L, normal = 1.31 to 1.37 mmol/L) were increased above values for adult females with normal calcium concentration. A tentative diagnosis of primary hyperparathyroidism was made. After a gamma-radiation scan and magnetic resonance imaging of the neck were done, exploratory surgery was performed to identify and remove the affected gland. After gland removal, the baboon's serum calcium, PTH (1.6 pmol/L), and ionized calcium (1.59 mmol/L) values decreased. Results of histologic examination confirmed the diagnosis of benign solitary parathyroid adenoma.

Metabolic disease in animals

Rickets is a metabolic bone disorder characterized by osteopenic changes resulting from the failure of calcification of the osteoid matrix and absent mineralization of hypertrophic cartilage cells at the epiphyseal growth plates in growing primates, herbivores, swine, carnivores, and birds. The causes of rickets include inadequate dietary provision of calcium, phosphorus, and vitamin D. Osteomalacia in reptiles, simian bone disease in nonhuman primates, and osteodystrophia fibrosa (secondary hyperparathyroidism) or "bran disease" in herbivores are caused by a diet that has a much higher content of phosphorus than calcium, combined with inadequate exposure to direct sunlight. Medullary bone consists of interconnected spicules of bone resembling embryonic bone and is established in relation to the shell formation cycle of laying birds. Hypertrophic osteodystrophy develops in large-breed growing dogs, chickens, and guinea pigs and is possibly caused by vitamin C deficiency. Tibial dyschondroplasia is a defect in endochondral ossification characterized by a widened proximal tibial physis that is not penetrated by metaphyseal vascular sprouts, commonly found in growing broiler chickens, turkeys, and exotic birds.

Primary hyperparathyroidism and concurrent hyperthyroidism in a cat

A cat was presented for anorexia and vomiting. Hyperthyroidism and primary hyperparathyroidism were diagnosed. A thyroid adenoma and parathyroid adenoma, respectively, were responsible for these conditions. Unilateral thyroidectomy and parathyroidectomy successfully resolved both disorders.

Percutaneous ultrasonographically guided radiofrequency heat ablation for treatment of primary hyperparathyroidism in dogs

OBJECTIVE

To evaluate the efficacy and safety of ultrasonographically guided radiofrequency heat ablation of parathyroid masses in dogs with primary hyperparathyroidism.

DESIGN

Clinical trial.

ANIMALS

11 dogs.

PROCEDURE

In all dogs, either 1 or 2 parathyroid masses were evident ultrasonographically. Dogs were anesthetized, and a 20-gauge over-the-needle catheter was directed into the parathyroid mass via ultrasonographic guidance. Radiofrequency heat was applied to the stylet of the catheter until there was sonographically apparent change to the entire parenchyma of the mass. Serum total and ionized calcium and parathyroid hormone concentrations were monitored daily for 5 days after the ablation procedure and again at 1, 2, and 3-month intervals, if possible. Dogs were monitored for adverse effects.

RESULTS

One treatment was required in 6 dogs, 2 treatments were required in 2 dogs, and treatment was unsuccessful in 3 dogs. Serum total and ionized calcium concentrations were within reference ranges within 2 days of the last procedure in all 8 successfully treated dogs. Serum parathyroid hormone concentration was decreased 24 hours after treatment in all 8 dogs. Hypocalcemia developed in 5 of the 8 successfully treated dogs, all of which required treatment. One dog had a transient voice change. Other adverse effects were not reported.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasonographically guided radiofrequency heat ablation of parathyroid masses is a safe and effective alternative to surgery in dogs with primary hyperparathyroidism.

[Ultrasonography of the parathyroid glands in dogs--a review]

The purpose of the study was to give an overview over the usefulness of ultrasonographic examination of parathyroid glands in dogs. By means of a 10 MHz high-resolution linear transducer it was possible to visualize parathyroid glands in healthy dogs. There was a positive correlation between body weight and size of the parathyroid glands, additionally the likelihood to detect 4 glands increased with an increase in body weight. Dogs with chronic renal failure had significantly larger parathyroid glands than healthy dogs and dogs with acute renal failure. In dogs with hypercalcemia of malignancy either none or parathyroids which were small in relation to body weight were detected. In contrast visualisation of parathyroid masses in dogs with primary hyperparathyroidism was easy due to their increased size and anechoic appearance. In dogs with severe azotemia the ultrasonographic examination of the parathyroid glands is helpful to differentiate between acute and chronic renal failure, in dogs with hypercalcemia to differentiate between hypercalcemia of malignancy and hypercalcemia due to primary hyperparathyroidism.

Ultrasound evaluation of the parathyroid glands in two hypercalcemic cats

Two parathyroid masses were identified using ultrasound in two hypercalcemic cats. The masses were identified as parathyroid adenomas on surgical biopsy. Both parathyroid masses contained hypoechoic regions with distal acoustic enhancement. Both masses were greater than 1.0 cm in diameter.

Survival of cats with naturally occurring chronic renal failure: effect of dietary management

Fifty cats with naturally occurring stable chronic renal failure (CRF) were entered into a prospective study on the effect of feeding a veterinary diet restricted in phosphorus and protein with or without an intestinal phosphate binding agent on their survival from initial diagnosis. Twenty-nine cats accepted the veterinary diet, whereas compliance (due to limited intake by the cats or owner resistance to diet change) was not achieved in the remaining 21. At diagnosis, both groups of cats were matched in terms of age, bodyweight, plasma creatinine, phosphate, potassium and parathyroid hormone (PTH) concentrations, packed cell volume and urine specific gravity. Feeding the veterinary diet was associated with a reduction in plasma phosphate and urea concentrations and prevented the increase in plasma PTH concentrations seen in cats not receiving the diet. Cats fed the veterinary diet survived for longer when compared with those that were not (median survival times of 633 versus 264 days). These data suggest that feeding a diet specifically formulated to meet the needs of cats with CRF, together with phosphate binding drugs if required, controls hyperphosphataemia and secondary renal hyperparathyroidism, and is associated with an increased survival time.

Hypercalcemia in cats: a retrospective study of 71 cases (1991-1997)

A retrospective study was conducted to characterize the diseases, clinical findings, and clinicopathologic and ultrasonographic findings associated with hypercalcemia (serum calcium concentration >11 mg/dL) in 71 cats presented to North Carolina State University Veterinary Teaching Hospital. The 3 most common diagnoses were neoplasia (n = 21), renal failure (n = 18), and urolithiasis (n = 11). Primary hyperparathyroidism was diagnosed in 4 cats. Lymphoma and squamous cell carcinoma were the most frequently diagnosed tumors. Calcium oxalate uroliths were diagnosed in 8 of 11 cats with urolithiasis. Cats with neoplasia had a higher serum calcium concentration (13.5 +/- 2.5 mg/dL) than cats with renal failure or urolithiasis and renal failure (11.5 +/- 0.4 mg/dL; P < .03). Serum phosphorus concentration was higher in cats with renal failure than in cats with neoplasia (P < .004). Despite the fact that the majority of cats with uroliths were azotemic, their serum urea nitrogen and creatinine concentrations and urine specific gravity differed from that of cats with renal failure. Additional studies are warranted to determine the underlying disease mechanism in the cats we identified with hypercalcemia and urolithiasis. We also identified a small number of cats with diseases that are not commonly reported with hypercalcemia. Further studies are needed to determine whether an association exists between these diseases and hypercalcemia, as well as to characterize the underlying pathophysiologic mechanism for each disease process.

Percutaneous ultrasound-guided chemical parathyroid ablation for treatment of primary hyperparathyroidism in dogs

OBJECTIVE

To evaluate the efficacy, feasibility, and safety of ultrasound-guided chemical ablation of parathyroid masses in dogs with primary hyperparathyroidism.

DESIGN

Prospective clinical trial.

ANIMALS

8 dogs.

PROCEDURE

In all dogs, a solitary parathyroid mass was evident ultrasonographically. Dogs were anesthetized with propofol, and a 27-gauge needle was directed into the parathyroid mass under ultrasound guidance. Ethanol (96%) was injected into the mass until there was evidence of diffusion of fluid throughout the mass. Serum total calcium, ionized calcium, phosphorus, and parathyroid hormone (PTH) concentrations were monitored daily for 5 to 7 days after the ablation procedure and again 1, 3, and 6 months after the procedure. Dogs were also monitored for adverse effects. Follow-up ultrasonography was performed 5 days and 1 month after the ablation procedure.

RESULTS

One injection was required in 7 dogs, and 2 injections were required in 1. Serum total and ionized calcium concentrations were within reference ranges within 24 hours after treatment in 7 dogs and within 5 days in 1 dog. Serum PTH concentration decreased and serum phosphorus concentration increased within 24 hours after treatment in all 8 dogs. Transient hypocalcemia developed in 4 dogs during the first 5 days after treatment, but only 1 dog required treatment for hypocalcemic tetany. Hypercalcemia recurred in 1 dog 1 month after the procedure and surgical removal of the parathyroid mass was required. Other adverse effects were not reported.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasound-guided chemical ablation of parathyroid masses is a safe and effective alternative to surgery for dogs with primary hyperparathyroidism.

Rat hypoplastic kidney (hpk/hpk) induces renal anemia, hyperparathyroidism, and osteodystrophy at the end stage of renal failure

In rats with genetically hypoplastic kidneys (hpk/hpk) and associated hypogonadism (hgn/hgn), their kidneys contain only one-quarter the number of nephrons that are found in those of normal rats [26]. Not surprisingly, therefore, renal excretive function has been shown to be depressed in hpk/hpk rats [26]. In the study presented here, we have examined the process of the progression of renal failure and the development of renal secondary disease in hpk/hpk rats. The plasma concentrations of urea-nitrogen and creatinine were significantly higher in adult hpk/hpk rats than in normal rats. These values elevated gradually and the degree of renal histological damage also progressed with advancing age in the hpk/hpk rats. In addition, renal anemia appeared at 140 days of age or later in these rats, and hyperplasia of the parathyroid glands was visible macroscopically at 280 days of age. In the hpk/hpk rats plasma levels of calcium and phosphorus were significantly lower and higher than in normal rats, respectively, at 280 days of age. Pathologically, the left femora of hpk/hpk rats exhibited fibrous osteodystrophy at 280 days of age and the calcium content of the right femora (as a percentage of the dry weight of bone) was significantly lower than in normal rats at both 210 and 280 days of age. These results indicate that the reduced nephrogenesis of the hpk/hpk rats causes progressive renal failure, secondarily inducing anemia, hyperparathyroidism, and osteodystrophy.

Resolution of metastatic calcification in the paws of a cat with successful dietary management of renal hyperparathyroidism

A 10-year-old ovariohysterectomised domestic shorthaired cat was presented with multiple nodular calcifications of the footpads and interdigital spaces. Renal insufficiency was diagnosed by routine biochemistry and urinalysis. Additionally, the cat had a calcium and phosphorus solubility product greater than 70 mg/dl and elevated circulating parathyroid hormone. Dietary management of the renal disease resulted in a reduction in the mineral solubility product and normalisation of the concentration of parathyroid hormone accompanied by concurrent resolution of the pedal lesions.

Primary hyperparathyroidism caused by a functional parathyroid adenoma in a horse

A 14-year-old Arabian gelding had weight loss and anorexia of 3 weeks' duration. Results of repeated laboratory tests revealed persistent hypercalcemia and serum phosphorus concentration that was within or less than the reference range. Parathyroid hormone concentration was high. Histologic examination of specimens obtained at necropsy revealed parathyroid adenoma. A diagnosis of primary hyperparathyroidism attributable to a functional parathyroid adenoma was made. Abnormalities in calcium and phosphorus concentrations were similar to those seen with primary hyperparathyroidism in dogs, in which this syndrome is best described. Primary hyperparathyroidism should be considered to be a potential cause of hypercalcemia in horses in which other more common causes of hypercalcemia, such as humoral hypercalcemia of malignancy, nutritional secondary hyperparathyroidism, chronic renal failure, vitamin D toxicosis, and bony or granulomatous disease, are ruled out.

[Differential diagnosis of hypercalcemia--a retrospective study of 46 dogs]

The case records of 46 dogs with hypercalcemia were studied retrospectively. The most common cause of hypercalcemia was malignancy, of which the majority were diagnosed as having lymphosarcoma (LSA, n = 23). Interestingly only 15 had palpable lymphadenopathy. Other neoplasia were apocrine adenocarcinoma of the anal sac (n = 4), mammary adenocarcinoma (n = 2), anaplastic carcinoma (n = 1), and malignant histiocytosis (n = 1). Non-neoplastic reasons for hypercalcemia were hypoadrenocorticism (n = 5), acute renal failure (n = 2), chronic renal failure (n = 2), hypervitaminosis D (n = 1), and primary hyperparathyroidism (n = 1). In 4 cases no definitive diagnosis could be obtained. Moderate to marked hyperphosphatemia and azotemia was found in all dogs with primary renal failure and in 4 of 5 dogs with hypoadrenocorticism. In contrast only 4 of 31 dogs with neoplasia showed (mild) hyperphosphatemia and 20 showed mild to moderate azotemia. Elevated PTH levels were found in dogs with primary chronic renal failure and with primary hyperparathyroidism, but also in one dog with neoplasia. Low PTH concentrations were measured in the dog with hypervitaminosis D and in 8 cases with neoplasia. Additional three cases with neoplasia had values in the reference range.

CONCLUSIONS

1. The most common cause of hypercalcemia is LSA. Absence of palpable lymphadenopathy does not exclude LSA and further diagnostic steps may be necessary 2. The combination of moderate to marked hyperphosphatemia suggests primary renal failure or hypoadrenocorticism. 3. An elevated PTH level is consistent with primary hyperparathyroidism, but does not exclude other causes of hypercalcemia.

Feline chronic renal failure: calcium homeostasis in 80 cases diagnosed between 1992 and 1995

Eighty cats with chronic renal failure (CRF) were evaluated in a prospective study to investigate the prevalence and aetiopathogenesis of renal secondary hyperparathyroidism (RHPTH), using routine plasma biochemistry and assays of parathyroid hormone (PTH), blood ionised calcium and 1,25 dihydroxycholecalciferol (1,25[OH]2D3). Hyperparathyroidism was a frequent sequela of CRF, affecting 84 per cent of cats with CRF, the severity and prevalence of RHPTH increasing with the degree of renal dysfunction. Compared with an age-matched control population, plasma concentrations of phosphate and PTH were significantly higher and 1,25(OH)2D3 concentrations were significantly lower in the two groups of cats presenting with clinical signs of CRF. Significant ionised hypocalcaemia was present only in cats with end-stage renal failure. However, a number of cats were hyperparathyroid in the absence of abnormalities in the parameters of calcium homeostasis measured in this study. There was a significant correlation between plasma phosphate and PTH concentrations.

Primary hyperparathyroidism with osteodystrophia fibrosa of the facial bones in a pony

A 17-year-old pony mare was admitted for evaluation of progressive enlargement of the facial bones during the preceding 9 months. Laboratory testing revealed that the pony had hypercalcemia, hypophosphatemia, high urinary fractional excretion of phosphorus, and high serum concentration of intact parathyroid hormone (185.1 pmol/L; reference range, 0.25 to 2.0 pmol/L). On the basis of these findings, a diagnosis of primary hyperparathyroidism was made by ruling out nutritional secondary hyperparathyroidism, chronic renal disease, and pseudohyperparathyroidism resulting from neoplasia. Although primary hyperparathyroidism is best treated by surgical removal of the affected parathyroid gland, the owners declined surgical exploration of the neck in this pony. Because of the poor prognosis, the pony was euthanatized. A functional lesion of the parathyroid tissue was not located on necropsy or histologic examination. Difficulty localizing and grossly identifying parathyroid tissue in horses complicates definitive diagnosis and treatment of primary hyperparathyroidism.

Comparison of results of hormonal analysis of samples obtained from selected venous sites versus cervical ultrasonography for localizing parathyroid masses in dogs

OBJECTIVE

To compare a technique in which samples obtained from selected venous sites are analyzed for parathyroid hormone (PTH) concentration versus usefulness of cervical ultrasonography for localizing primary hyperparathyroidism (PHP) in dogs.

DESIGN

Prospective study.

ANIMALS

12 dogs with PHP.

PROCEDURE

For each dog, blood samples were collected from the left and right jugular veins and 1 cephalic vein for determination of serum PTH concentration. Ultrasonography of the neck was performed in each dog. Each dog underwent exploratory surgery of the neck. Abnormal appearing parathyroid tissue was removed. Dogs were included in the study if serum calcium concentration decreased within 12 hours after surgery, hypercalcemia completely resolved within 96 hours after surgery, and serum calcium concentration was maintained within the reference range for at least 6 months after surgery.

RESULTS

Serum PTH concentrations from the 3 veins were similar in 11 of 12 dogs with PHP. In 1 dog, the serum PTH concentration from the jugular vein ipsilateral to a parathyroid adenoma was greater than that from the contralateral jugular or cephalic vein. Ultrasonography correctly identified a parathyroid mass and its location in 10 of 11 dogs with a solitary abnormal parathyroid gland and in 1 dog in which both parathyroid glands were enlarged.

CLINICAL IMPLICATIONS

Surgeons may benefit from knowing the location of abnormal parathyroid tissue in dogs with PHP before surgical exploration. Ultrasonography has potential value for identifying and localizing abnormal parathyroid tissue, whereas sample collection from selected sites for PTH analysis is not likely to be helpful.

Primary hyperparathyroidism in two cats

Primary hyperparathyroidism (PHP) is an infrequently diagnosed disorder in cats. In this report the signs and symptoms of two cats with hypercalcaemia due to PHP are described, together with diagnostic approach, results of treatment, and immunohistochemical findings. A 9-year-old and a 13-year-old neutered male domestic shorthair cat were presented with signs of lethargy, anorexia, and vomiting. Both cats had persistent hypercalcaemia and normo- to hypophosphataemia. Cytological examination of a fine-needle aspiration biopsy sample of a palpable cervical mass revealed groups of benign glandular-epithelial cells in one cat. In the other cat no cervical mass was palpable. In this cat plasma parathyroid hormone (PTH) levels were measured repeatedly and these values exceeded the maximum reference value on two occasions. Following exclusion of other causes of hypercalcaemia both cats were subjected to neck surgery and in both a solitary parathyroid adenoma was removed. The adenomas contained an abundance of PTH, as demonstrated by immunohistochemical techniques. Plasma calcium and phosphate concentrations returned to within, reference ranges postoperatively. Recovery was uncomplicated and there were no signs of recurrence on follow-up examinations.

Use of technetium Tc 99m sestamibi for detection of a parathyroid adenoma in a dog with primary hyperparathyroidism

Double-phase parathyroid gland scintigraphy, using technetium Tc 99m sestamibi, correctly identified the existence and location of a parathyroid adenoma in a dog with primary hyperparathyroidism. The parathyroid adenoma was removed surgically 2 days after scintigraphy. An area of focal radionuclide uptake persisted in the region corresponding to the left external parathyroid gland in the delayed-phase image. Delayed-phase images from 3 healthy dogs and a dog with hypercalcemia of malignancy caused by lymphoma did not reveal an area of persistent radiotracer uptake. Double-phase parathyroid gland scintigraphy, using 99mTc-sestamibi, is a simple, rapid, noninvasive test, which can be used for detection and localization of parathyroid adenomas in hypercalcemic dogs. It also can help to differentiate these dogs from dogs with hypercalcemia of malignancy.

Nasal obstruction caused by nutritional osteodystrophia fibrosa in a group of Ethiopian horses

A severe, advanced case of nutritional osteodystrophia fibrosa is described in a 10-year-old gelding with primary upper respiratory obstruction and chronic weight loss, which was one of a group of similarly affected horses in Ethiopia. The diagnosis was based on the clinical signs, gross lesions, histopathology and management history. The affected bones had suffered severe mineral depletion.

Calcium oxalate urolithiasis in a cat with a functional parathyroid adenocarcinoma

A 9-year-old castrated male domestic shorthair cat with dysuria, anorexia, vomiting, and lethargy was admitted to the veterinary teaching hospital. A large, firm mass was palpable in the ventral cervical region. Hypercalcemia, azotemia, and nonregenerative anemia were evident on serum biochemical analysis and CBC, and multiple uroliths were detected by abdominal radiography. At necropsy, light microscopy of the ventral cervical mass revealed a parathyroid adenocarcinoma. Light microscopy of sections of the kidneys revealed multifocal, chronic, lymphocytic/plasmacytic, tubulointerstitial nephritis, as well as moderate multifocal acute tubular necrosis. On quantitative analysis, the uroliths were composed of calcium oxalate. Determination of serum calcium concentration is indicated in cats with calcium oxalate urolithiasis to aid in detection of primary hyperparathyroidism.

Diagnostic and therapeutic considerations in a hypercalcemic dog with multiple endocrine neoplasia

Hypercalcemia was found in a dog examined for episodic weakness and disorientation. A right adrenal mass identified on abdominal ultrasonographic examination was diagnosed as a pheochromocytoma based on increased 1231-metaiodobenzylguanidine uptake and characteristic histopathological features. Serum intact parathyroid hormone (iPTH), total serum calcium, and ionized serum calcium were increased prior to surgery. Although both total and ionized serum calcium concentrations decreased to within normal reference ranges following surgery through postoperative day 17, subsequent high concentrations with increased serum iPTH concentrations confirmed concurrent primary hyperparathyroidism. A right parathyroid tumor was suspected based on a technetium-99m-sestamibi (99mTc-sestamibi) scan.

Surgical therapy of the thyroid

The surgical treatment of thyroid cancer in the cat involves excision of one or both thyroid glands while sparing at least one parathyroid gland. The most common postoperative complication of bilateral thyroidectomy is transient hypocalcemia. Most feline thyroid tumors are benign, hyperfunctional thyroid adenomas. Surgical excision is usually curative. Canine thyroid cancer is most commonly malignant and nonfunctional. Successful surgical treatment of canine thyroid cancer depends on histologic and early diagnosis prior to metastasis or invasion of the cancer into adjacent structures within the neck.

Primary parathyroid gland hyperplasia in dogs: six cases (1982-1991)

Persistent hypercalcemia attributable to parathyroid gland hyperplasia was identified in 6 dogs with primary hyperparathyroidism. Clinical signs included polydipsia (n = 4), polyuria (n = 4), and signs caused by cystic calculi (n = 3). Abnormal clinical pathologic findings included hypercalcemia (mean, 13.6 mg/dl; range, 12.6 to 14.7 mg/dl; n = 6), hypophosphatemia (mean, 2.2 mg/dl; range, 1.4 to 2.9 mg/dl; n = 6), high serum alkaline phosphatase activity (mean, 222 IU/L; range, 161 to 286 IU/L; n = 3), and isosthenuria (mean, 1.012; range, 1.006 to 1.017; n = 6). Serum parathyroid hormone concentration was within the reference range or high (mean, 23 pmol/L; range, 7 to 119 pmol/L; reference range, 1.5 to 13 pmol/L) in all dogs. At surgery, the number of large parathyroid glands was variable, being limited to 1 gland in 3 dogs, 2 glands in 2 dogs, and 4 glands in 1 dog. All visibly large parathyroid glands were surgically removed from each dog. Serum calcium concentration decreased into or below the reference range within 72 hours of surgery in all dogs, confirming the diagnosis of primary parathyroid disease. Multiple nodules of adenomatous hyperplasia were identified in each dog. All 6 dogs were treated with vitamin D and calcium carbonate following surgery. The dog from which all 4 parathyroid glands were removed has remained eucalcemic for more than 1 year with vitamin D supplementation. Vitamin D and calcium administration was discontinued within 4 to 12 weeks of surgery in the remaining 5 dogs. These dogs remained eucalcemic without vitamin D supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Nephrocalcinosis caused by hyperparathyroidism in progression of renal failure: treatment with calcitriol

Nephrocalcinosis is accepted to contribute to the progression of renal failure. We have reviewed evidence that nephrocalcinosis is caused directly by the excess parathyroid hormone produced in renal disease. Evidence that hyperparathyroidism in uremic patients results from calcitriol deficiency and the mechanisms by which this comes about have been discussed. We have shown that renal secondary hyperparathyroidism can be eliminated or substantially reduced without increasing blood calcium using a low-dosage regimen of calcitriol. Decreasing PTH concentrations to or near normal alleviates this hormone's toxicity to many organs, including the kidneys. Potential benefits for the uremic patient include an increase in the quality and length of life. Calcitriol treatment provides a powerful means to reduce PTH concentration in uremic patients that may not be achieved with other methods. Further prospective clinical studies of uremic dogs and cats are warranted to document preservation of renal function and histology during calcitriol treatments.

Primary hyperparathyroidism in cats: seven cases (1984-1989)

The medical records of 7 hypercalcemic cats with primary hyperparathyroidism were evaluated. Mean age was 12.9 years, with ages ranging from 8 to 15 years; 5 were female; 5 were Siamese, and 2 were of mixed breed. The most common clinical signs detected by owners were anorexia and lethargy. A cervical mass was palpable in 4 cats. Serum calcium concentrations were 11.1 to 22.8 mg/dl, with a mean of 15.8 mg/dl calculated from each cat's highest preoperative value. The serum phosphorus concentration was low in 2 cats, within reference limits in 4, and slightly high in 1 cat. The BUN concentration was greater than 60 mg/dl in 2 cats, 31 to 35 mg/dl in 2 cats, and less than 30 mg/dl in 3 cats. Abnormalities were detected in serum alanine transaminase, aspartate transaminase, and alkaline phosphatase activities from 2 or 3 cats. Parathormone (PTH) concentrations were measured in 2 cats before and after surgery. The preoperative PTH concentration was within reference limits in 1 cat and was high in 1 cat. The PTH concentrations were lower after surgery in both cats tested. A solitary parathyroid adenoma was surgically removed from 5 cats, bilateral parathyroid cystadenomas were surgically resected in 1 cat, and a parathyroid carcinoma was diagnosed at necropsy in 1 cat. None of the cats had clinical problems with hypocalcemia after surgery, although 2 cats developed hypocalcemia without tetany, one of which was controlled with oral administration of dihydrotachysterol and the other with oral administration of 1,25 dihydroxyvitamin D. All 5 of the cta that underwent removal of an adenoma were alive at least 240 days after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical management of collapsed pelvis in a jaguar

An immature jaguar was surgically treated for severe constipation caused by a narrow pelvic canal. This narrowing was attributed to nutritional secondary hyperparathyroidism. The ventral floor of the pelvis was widened by placing a piece of high density polyethylene between the 2 sides of the pubis after symphysiotomy and stabilizing the implant with orthopedic wires. This procedure provided stable fixation and permanent enlargement of the pelvic canal. The technique was easy to perform and could be used to treat pelvic collapse in other species.

Intact parathyroid hormone assay and total calcium concentration in the diagnosis of disorders of calcium metabolism in dogs

Serum samples from eight dogs with primary hyperparathyroidism, seven dogs with hypercalcemic lymphosarcoma (hypercalcemia of malignancy), and four dogs with primary hypoparathyroidism were submitted to the Animal Health Diagnostic Laboratory at Michigan State University for intact parathyroid hormone (PTH) assay. When compared with the adjusted total serum calcium concentration, the intact PTH concentration was consistent with the correct diagnosis in all cases. Two dogs with hypercalcemic lymphosarcoma were mildly azotemic. In both of these cases the intact PTH concentration was consistent with hypercalcemia of malignancy despite the presence of azotemia. These data support a significant role for intact serum PTH assay in the differential diagnosis of disorders of calcium metabolism.

Seizures as a manifestation of primary hyperparathyroidism in a dog

Hypercalcemia caused by primary hyperparathyroidism was believed to be responsible for seizures in a dog. A diagnostic evaluation showed no primary causes of seizures. After surgical excision of the adenomatous parathyroid gland, phenobarbital treatment was discontinued, without recurrence of seizures.