Diagnosis of secondary hyperparathyroidism in a pony using intact parathyroid hormone radioimmunoassay

Treatment of primary hyperparathyroidism in a Miniature Horse using chemical ablation of abnormal parathyroid tissue localized by 3-phase computed tomography

A 15‐year‐old Miniature Horse mare with persistently increased plasma calcium (total and ionized) and serum parathyroid hormone concentrations was presented for suspected primary hyperparathyroidism. Ultrasonography of the thyroid region identified an enlarged heterogeneous mass axial to the right thyroid lobe suggestive of an enlarged parathyroid gland, which was further confirmed using sestamibi nuclear scintigraphy and 3‐phase computed tomography. Percutaneous ultrasound‐guided ethanol ablation of the mass, a method not previously described in the horse, was performed under general anesthesia resulting in rapid normalization of plasma ionized calcium and serum parathyroid hormone concentrations. Ablation of abnormal parathyroid gland tissue may be a suitable alternative to surgical resection in certain cases of primary hyperparathyroidism in the horse.

Diagnosis and treatment of confirmed and suspected primary hyperparathyroidism in equids: 17 cases (1999-2016)

BACKGROUND

Primary hyperparathyroidism is uncommon in equids.

OBJECTIVES

To describe the diagnostic findings and efficacy of treatment in equids with primary hyperparathyroidism.

STUDY DESIGN

Retrospective case series describing 16 horses and one mule.

METHODS

Cases were identified by retrospective review of records at Cornell University and via an ACVIM listserv query. Inclusion criteria were an equid with hypercalcemia, normal renal function and high parathyroid hormone (PTH) or histopathological diagnosis of a parathyroid adenoma. Equids with normal PTH and PTH-related protein (PTHrP) in the face of hypercalcemia were included as suspect cases.

RESULTS

The most common presenting complaints were weight loss (12/17) and hypercalcemia (10/17). PTH was above reference range in 12/17 cases. Suspected parathyroid tumours were localised in 12/14 equids imaged using ultrasonography alone (2/3), technetium 99m Tc sestamibi scintigraphy alone (1/1) or both modalities (9/10). Three horses did not have imaging performed. Surgical exploration successfully excised tumours in six of 10 cases. Five were located at the thoracic inlet, and surgery resulted in complete cure. One tumour was excised from the thyroid lobe, and the horse remained hypercalcemic. Four other cases explored surgically, four treated medically and three that were not treated also remained hypercalcemic.

MAIN LIMITATIONS

The small study size prohibited statistical analysis.

CONCLUSIONS

Parathyroid adenomas in equids can be successfully localised with ultrasonography and scintigraphy. Surgical excision appears more likely to be successful for single gland disease at the thoracic inlet.

Nutritional secondary hyperparathyroidism in two ponies

Nutritional secondary hyperparathyroidism (NSH) is uncommon in horses. Aim of this report is evaluate an alternative therapeutic approach and provide more information on the diagnostic procedures, through detailed microscopic findings of the bone lesions pony with NSH. Administration of tiludronate along with a balanced diet can be used in a treatment protocol for ponies with NSH. This case report suggests that tiludronate can be used to ameliorate the clinical signs of NSH.

Hematologic, Biochemical, and Endocrine Parameters in Horses With Tooth Resorption and Hypercementosis

Background:

Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a frequently diagnosed condition in adult horses. The underlying etiology is still unknown. Hematologic, biochemical, and endocrine values have not been reported in EOTRH-affected horses.

Objectives:

The main objective of the study was to describe the hematologic, biochemical, and endocrine parameters in horses with EOTRH.

Study Design:

Descriptive cross-sectional study of client-owned animals with EOTRH.

Methods:

A complete blood count, biochemistry panel, and endocrine profile were performed in horses diagnosed with EOTRH. Diagnosis was based on oral and radiographic examination findings and confirmed with histopathology.

Results:

Eighteen horses with EOTRH aged 10 to 32 years from various regions of the United States were sampled. The only consistent abnormality on the complete blood cell count and chemistry panel was hypoalbuminemia (88%). Endocrine parameters demonstrated no major abnormalities in the functioning of the thyroid and pituitary pars intermedia. The parathyroid hormone concentration was increased in 7 (47%) of 15 horses with an elevated 25-hydroxy vitamin D in 3 (17%) of 17 horses.

Main Limitations:

The main limitations of this study are the small sample size and lack of age-matched and management-matched control horses.

Conclusions:

The relevance of elevated parathyroid hormone in this study cannot be determined due to the lack of age-based controls and large population studies. With the small population evaluated in this study, there are no obvious hematological, biochemical, and endocrine changes evident. Further evaluation with signalment-matched controls will be necessary to evaluate some trends noted in the laboratory values.

Persistent Hypercalcemia and Hyperparathyroidism in a Horse

A 27-year-old, American Quarter Horse gelding was evaluated for anorexia, lethargy, a swelling on the right, cranial aspect of the neck, and signs of esophageal obstruction. Serum biochemical analyses revealed hypophosphatemia, total and ionized hypercalcemia, and hemoconcentration. Sonographic examination of the neck revealed a 1.7 cm diameter mass within the right lobe of the thyroid. The serum concentration of intact parathyroid hormone (iPTH) was increased. The right lobe of the thyroid was excised with the horse sedated. The mass within that lobe was determined, by histological examination, to be a parathyroid adenoma. Despite excision of the mass, serial blood analyses revealed persistent hypercalcemia, hypophosphatemia, and increased iPTH. Anorexia and lethargy resolved, and follow-up communication with the owner and referring veterinarian one year later indicated that the horse was clinically stable.