A challenging case: Primary hyperparathyroidism in a dog - Veterinary Medicine
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A challenging case: Primary hyperparathyroidism in a dog
Ultrasonographic examinations helped identify the source of this dog's persistent hypercalcemia.


VETERINARY MEDICINE


Abdominal exploration, cystotomy, and bone marrow biopsy

The dog was sedated with butorphanol and midazolam. Anesthesia was induced with propofol and maintained with isoflurane. An abdominal exploratory surgery and cystotomy were performed, and multiple, 3-to-4-cm, smooth, oval calculi were removed from the urinary bladder. The bladder was closed in a routine fashion. Liver, gastric, and intestinal biopsy samples were obtained for histologic examination to rule out possible underlying gastrointestinal or multicentric lymphoma. The abdomen was closed in a routine fashion.

A bone marrow core biopsy sample from the right humerus was also obtained and submitted for histologic examination to rule out occult lymphoma, leukemia, and multiple myeloma. Postoperative abdominal radiographs documented that all calculi had been removed.

Postoperative care

After surgery, the dog received famotidine (0.5 mg/kg orally once daily for seven days), enrofloxacin (5 mg/kg orally once daily for seven days), and meloxicam (0.1 mg/kg every 24 hours for seven days). The thyroxine, tylosin, and therapeutic diet were continued as previously prescribed. Recovery from surgery was uneventful, and the dog was discharged to its owners the next day. Histologic examination of the liver, gastric, intestinal, and bone marrow biopsy samples revealed no abnormalities. The cystic calculi analysis revealed calcium oxalate composition.

FOLLOW-UP EVALUATIONS

The referring practitioner monitored the dog's total calcium concentration monthly. At the three-month check, the dog's ionized calcium concentration had increased to 1.93 mmol/L. The PTH concentration was 12.2 pmol/L, and the PTHrP concentration remained undetectable.


1. A sagittal ultrasonogram of the right thyroid and parathyroid glands, with the patient in dorsal recumbency. The top of the image is ventral, and the left of the image is cranial. The parathyroid adenoma is hypoechoic compared with the surrounding thyroid tissue. The diameter of the mass is 0.36 cm.
An ultrasonographic examination of the parathyroid glands revealed a 3.6-x-3-mm mass on the right cranial parathyroid gland. The mass was hypoechoic compared with the surrounding thyroid tissue (Figure 1). The remaining three parathyroid glands appeared to have normal echotexture but were markedly smaller. Primary hyperparathyroidism was diagnosed.

Parathyroidectomy

The next day, the dog was anesthetized as described for the cystotomy and taken to surgery for parathyroid gland exploration. Patient monitoring and intraoperative support included continuous blood pressure and ECG monitoring and pulse oximetry. A ventral cervical approach was used, and surgical dissection of the right thyroid gland revealed a 3.6-mm, round, raised mass in the cranioventral aspect of the right cranial parathyroid gland. The parathyroid glad was removed and the mass was submitted for histologic examination. The surgical site was closed in routine fashion. The dog's total calcium concentration was 3.45 mmol/L before surgery and 3.22 mmol/L six hours after surgery.

Postoperative care and outcome

After surgery, calcium carbonate was administered (1,000 mg orally every 12 hours for 14 days). On postoperative day 2, the dog's total calcium concentration was 3.05 mmol/L, and calcitriol was initiated (250 ng orally every 12 hours for 30 days) to promote intestinal absorption of calcium. On day 3, the total calcium concentration decreased to 2.73 mmol/L. On day 4, the total calcium concentration stabilized at 2.78 mmol/L, and the dog was discharged from the hospital with instructions to administer meloxicam (0.1 mg/kg every 24 hours for seven days) and continue the thyroxine and tylosin as previously prescribed.


2. A photomicrograph of the parathyroid ademona (hematoxylin-eosin; bar = 10 ).
Histologic examination of the mass was consistent with a completely excised parathyroid adenoma (Figure 2). At a follow-up examination one year later, the dog's calcium concentration was normal without calcium and calcitriol supplementation.


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Source: VETERINARY MEDICINE,
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