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.

Pituitary tumour types in dogs and cats.

Pituitary tumours are common in dogs and are being increasingly recognized in cats. Pituitary tumours are usually classified as adenomas and should only be classified as carcinomas when there is evidence of metastatic spread of the tumour, which is rare. Despite the benign nature of most pituitary tumours, they can still compress or invade neighbouring tissues. Pituitary tumours can be functional (hormonally active) or non-functional (hormonally silent). The aim of this review was to provide an overview of the different pituitary tumour types in dogs and cats that have been reported in the literature. In dogs, the most common pituitary tumour type is the corticotroph adenoma, which can cause pituitary-dependent hypercortisolism. In cats, the most common pituitary tumour is the somatotroph adenoma, which can cause hypersomatotropism, and the second-most common is the corticotroph adenoma. A lactotroph adenoma has been described in one dog, while gonadotroph, thyrotroph and null cell adenomas have not been described in dogs or cats. Hormonally silent adenomas are likely underdiagnosed because they do not result in an endocrine syndrome. Tools used to classify pituitary tumours in humans, particularly immunohistochemistry for lineage-specific transcription factors, are likely to be useful to classify canine and feline pituitary tumours of unknown origin. Future studies are required to better understand the full range of pituitary adenoma pathology in dogs and cats and to determine whether certain adenoma subtypes behave more aggressively than others. Currently, the mechanisms that underlie pituitary tumorigenesis in dogs and cats are still largely unknown. A better understanding of the molecular background of these tumours could help to identify improved pituitary-targeted therapeutics.

Updates in Feline Diabetes Mellitus and Hypersomatotropism.

Flash glucose monitoring is a novel, noninvasive monitoring technique that is increasingly used in the management of small animal diabetes. This article provides guidance on the use of flash glucose monitoring in cats and demonstrates how this technique can be used in a range of feline diabetic cases, including those where management is proving challenging. Other aspects of complicated feline diabetic care are also discussed, including management of the sick diabetic cat, potassium depletion myopathy, and treatment options for cats with hypersomatotropism-associated diabetes mellitus. The use of insulin glargine 300 U/ml as a promising new long-acting insulin for diabetic cats is also discussed.

[Acromegaly due to a pituitary tumor in a dog - diagnosis, therapy and long-term follow-up]. / Akromegalie aufgrund eines Hypophysentumors bei einem Hund ­ Diagnose, Therapie und Verlauf.

INTRODUCTION: Acromegaly due to a pituitary tumor has so far only been described in 3 dogs. The present case report describes a 7-year-old male-castrated Labrador Retriever which was referred because of difficult-to-control diabetes. Physical examination revealed markedly enlarged head, tongue and paws, widened interdental spaces and thickening of the skin in the head and neck area. IGF-1 and GH were increased and the latter continued to be abnormal after somatostatin application. Computed tomography demonstrated a space-occupying lesion in the pituitary gland and the diagnosis of acromegaly due to a GH-producing tumor of the pituitary was made. The dog underwent radiation therapy with a 6MV linear accelerator (3×8Gy) and improved substantially. Two and a half years after radiation therapy the dog developed lethargy and anorexia and was euthanized. Necropsy was not permitted. This case report represents the description of a dog suffering from pituitary-dependent acromegaly which was successfully treated and had a long-term survival.

INTRODUCTION: L'acromégalie due à une tumeur hypophysaire n'a jusqu'à présent été décrite que chez 3 chiens. Le présent rapport de cas décrit un Labrador Retriever de 7 ans mâle castré, qui a été référé en raison d'un diabète difficile à contrôler. L'examen physique a révélé une tête, une langue et des pattes de taille nettement augmentée, des espaces interdentaires élargis et un épaississement de la peau dans la région de la tête et du cou. L'IGF-1 et la GH étaient augmentées et la seconde restait anormale après l'application de somatostatine. La tomodensitométrie a mis en évidence une masse dans la région de l'hypophyse et le diagnostic d'acromégalie due à une tumeur de l'hypophyse productrice de GH a été posé. Le chien a subi une radiothérapie avec un accélérateur linéaire de 6MV (3×8Gy) et son état s'est considérablement amélioré. Deux ans et demi après la radiothérapie, le chien développa une léthargie et une anorexie et fut euthanasié. L'autopsie n'a pas été autorisée. Ce rapport de cas représente la description d'un chien souffrant d'acromégalie dépendant de l'hypophyse, traité avec succès et ayant une survie à long terme.

Radiotherapy and pasireotide treatment of a growth hormone producing pituitary tumor in a diabetic dog.

An 8-year-old castrated male border terrier dog was diagnosed with acromegaly resulting from a growth hormone secreting pituitary tumor. Sixteen daily fractions of radiation therapy were delivered followed, approximately 1 year later, by administration of pasireotide. The aforementioned treatment was considered effective and should be further evaluated in similar cases.

Radiothérapie et traitement au pasiréotide pour une tumeur pituitaire produisant une hormone de croissance chez un chien diabétique. Un chien Terrier-Border castré âgé de 8 ans a été diagnostiqué avec de l'acromégalie découlant d'une tumeur pituitaire secrétant une hormone de croissance. Seize fractions quotidiennes de radiothérapie ont été administrées et ont été suivies, environ un an plus tard, de l'administration du pasiréotide. Le traitement précédemment mentionné a été considéré efficace et devrait être étudié de plus près dans des cas similaires.(Traduit par Isabelle Vallières).

Stereotactic radiation therapy for the treatment of functional pituitary adenomas associated with feline acromegaly.

BACKGROUND: Conventional fractionated radiotherapy has been shown to be partially effective for management of pituitary tumors in cats that cause acromegaly and diabetes mellitus (DM), but, the efficacy and safety of stereotactic radiation therapy (SRT) as a treatment for acromegalic cats has not been described. HYPOTHESIS: Stereotactic radiation therapy is an effective and safe treatment for controlling acromegaly associated with pituitary adenomas in cats. Additionally, SRT-treated acromegalic cats with DM will experience a decrease in insulin requirements after radiation therapy. ANIMALS: Fifty-three client-owned cats referred to Colorado State University for SRT to treat pituitary tumors causing poorly controlled DM secondary to acromegaly. METHODS: Retrospective study of cats treated for acromegaly with SRT between 2008 and 2016 at Colorado State University. Diagnosis of acromegaly was based on history, physical examination, laboratory results, and cross-sectional imaging of the pituitary. Signalment, radiation protocol, insulin requirements over time, adverse effects, and survival were recorded. RESULTS: Median survival time was 1072 days. Of the 41 cats for which insulin dosage information was available, 95% (39/41) experienced a decrease in required insulin dose, with 32% (13/41) achieving diabetic remission. Remission was permanent in 62% (8/13) and temporary in 38% (5/13) cats. Median duration to lowest insulin dose was 9.5 months. Of the treated cats, 14% developed hypothyroidism and required supplementation after SRT. CONCLUSIONS: Stereotactic radiation therapy is safe and effective for treating cats with acromegaly. Cats treated with SRT have improved survival time and control of their DM when compared to previously reported patients treated with non-SRT.

Feline acromegaly.

Acromegaly, or hypersomatotropism, results from chronic, excessive secretion of growth hormone in the adult animal. The anabolic effects of growth hormone are exerted through the intermediary hormone, insulin-like growth factor 1, which is produced in the liver under the influence of growth hormone. Feline acromegaly is caused by a pituitary adenoma that secretes excessive amounts of growth hormone. Characteristic effects of excessive growth hormone secretion include the development of diabetes mellitus and growth of the acral segments of the body (jaw, extremities, skull, etc.). Acromegaly occurs in older, predominately male cats and is often associated with diabetes mellitus. Other clinical signs include stridor, enlargement of the jaw and extremities, lean weight gain, and organomegaly (heart, liver, kidney, etc.). Diagnosis is made by documentation of increased levels of growth hormone or insulin-like growth factor (or both) and demonstration of a pituitary mass via magnetic resonance imaging or computed tomography. The most effective treatment to date has been radiation therapy. Prognosis is fair to good with proper treatment.