Spontaneous acromegaly: A retrospective case control study in German shepherd dogs

Transsphenoidal hypophysectomy for the treatment of hypersomatotropism secondary to a pituitary somatotroph adenoma in a dog

Pituitary-dependent hypersomatotropism is rarely diagnosed in dogs and surgical treatment is not reported. A 6-year-10-month male neutered Patterdale Terrier presented with polyuria, polydipsia, progressive pharyngeal stertor, excessive hair growth and widened facial features and paws. Serum insulin-like growth factor-1 concentration via radioimmunoassay was consistent with hypersomatotropism (1783 ng/mL). A pituitary mass was identified on magnetic resonance and computed tomography imaging. Six weeks later, glucosuria, starved hyperglycemia and serum fructosamine above the reference range (467.6 μmol/L, RI 177-314) were documented, consistent with diabetes mellitus. Transsphenoidal hypophysectomy was performed under general anesthesia without complications. Pituitary histopathology identified an acidophil neoplasm, with positive immunostaining for growth hormone. Postoperatively, there was rapid resolution of clinical, biochemical and morphologic changes of hypersomatotropism with persistence of diabetes mellitus. This case demonstrates successful resolution of hypersomatotropism with ongoing diabetes mellitus in a dog after surgical treatment by transsphenoidal hypophysectomy.

Acromegaly in dogs and cats

Acromegaly is an endocrine disease that leads to elevated production and secretion of growth hormone (GH). It can occur in adult and aged cats and is usually associated with neoplasms, such as functional pituitary macroadenoma of somatotropic cells. In dogs it is usually related to an increase in serum progesterone that induces production of GH by the mammary glands. The main clinical signs are related to insulin resistance and the anabolic effect induced by GH: polyuria, polydipsia, polyphagia, increased tissue growth, weight gain, prognathism, and other changes. The condition can be diagnosed from clinical signals and imaging associated to measurement of serum concentrations of GH and insulin-like growth factor 1 (IGF-1, also known as somatomedin C). The main therapeutic modalities are radiotherapy, hypophysectomy, and several drugs such as somatostatin analogs, dopaminergic agonists and GH receptor antagonists. The present review aims to provide a relevant animal model of acromegaly with an update on the therapeutic approach that may help clinicians to consider the GH axis-IGF-1 system, its pathogenesis and the clinical signs induced by this hormonal disorder.

Urinary excretion of calcium and phosphate in dogs with pituitary-dependent hypercortisolism: case control study in 499 dogs

Pituitary-dependent hypercortisolism (PDH) in dogs is frequently associated with high serum phosphate and parathormone concentrations which are in turn associated with prognosis and clinical presentation. The pathogenesis of such abnormalities remains unknown. The aim of the present study was to evaluate the serum and urinary concentrations and the urinary fractional excretion of phosphate and calcium in dogs with PDH. Medical records of newly diagnosed PDH dogs before treatment from one referral centre were retrospectively evaluated. One clinically normal and one sick dog for each dog with PDH were included as controls. One hundred and sixty-seven dogs with PDH were included. The serum phosphate concentration in PDH dogs was significantly (P<0.0001) higher compared with clinically normal control dogs (CNDs) and sick control dogs (SCDs). The serum calcium concentration in PDH dogs was significantly higher compared with SCDs but not different compared with CNDs. Urinary fractional excretion of phosphate in PDH dogs was significantly lower compared with CNDs and SCDs. Urinary fractional excretion of calcium in PDH dogs was significantly higher compared with CNDs and SCDs. In conclusion, PDH dogs have lower phosphaturia and higher calciuria compared with control dogs. These findings suggest that, at least in part, high serum phosphate concentrations are related to the renal retention of phosphate.