The pituitary gland in horses is a small, yet significant endocrine organ located at the base of the brain. It is responsible for producing and releasing hormones that regulate various physiological processes, including growth, metabolism, and reproduction. The gland is divided into two main parts: the anterior pituitary, which secretes hormones such as adrenocorticotropic hormone (ACTH) and growth hormone (GH), and the posterior pituitary, which releases hormones like vasopressin and oxytocin. Changes or dysfunctions in pituitary function can lead to conditions such as pituitary pars intermedia dysfunction (PPID), commonly known as equine Cushing's disease, which affects older horses. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and clinical implications of the pituitary gland in equine health.
SAXENA BB, McSHAN WH, MEYER RK.Fresh horse-pituitary glands were extracted with 40% ethanol and the gonadotropins were recovered by increasing the alcohol concentration to 85% followed by drying with acetone. This preparation was further extracted with water at pH 5, and the extract was adjusted to pH 7 and lyophilized. The follicle-stimulating hormone in the pH-5-souluble fraction was purified by zone electrophoresis and resolved into six components by starch-gel electrophoresis. One of these components contained follicle-stimulating hormone which was recovered in the elution cell and the contaminating starch was separated...
KIVALO E, TALANTI S.A good deal of hypothetical evidence has been presented for the view that the antidiuretic and oxytocic hormones are not produced in the posterior lobe of the hypophysis. These hormones appear to originate from a neurosecretory process in the neurosecretory nerve cells of the supraoptic and paraventricular nuclei in the hypothalamus and to migrate within the nerve fibers of the supraoptico-hypophysial tract and into the neurohypophysis (Hild, 1951, 1954 a, b and Hild & Zetler, 1951, 1952, 1953 a, b). Here they are stored and if necessary released. Neurosecretory neurons are described in many s...
Drozdzewska K, Winter J, Barton AK, Merle R, Gehlen H.The basal (bACTH) and post-thyrotropin-releasing hormone stimulation concentration of adrenocorticotropin (pACTH) are recommended for diagnosis of pituitary pars intermedia dysfunction (PPID). Many factors influence bACTH (e.g., disease, age, month) and some affect the results only in autumn (e.g., breed, colour, sex). There are discrepancies about the impact of feeding on b/pACTH. Objective: To determine whether feeding, month, age, breed, colour, sex and body condition score affect b/pACTH. Methods: Prospective crossover. Methods: Sixty-one animals were divided into groups: healthy, PPID, tr...
Colbath AC, Fortin JS, Burglass CM, Panek C, Vergara-Hernandez FB, Johnson TN, Robison CA, Logan AA, Nelson NA, Nielsen BD, Schott HC.Pathological fractures have been reported in equids with pituitary pars intermedia dysfunction (PPID) but their prevalence and pathogenesis is unknown. Objective: To compare: (1) bone mineral density (BMD) in weight bearing and nonweight bearing bones in PPID+ equids and aged and young PPID- controls; and (2) biomechanical properties of the fourth lumbar vertebral body in PPID+ equids and aged PPID- equids. Methods: Case-control study: five PPID+ equids and six aged and four young PPID- control horses. Methods: PPID status was based on clinical signs and necropsy examination of the pituitary g...
Clark BL, Norton EM, Bamford NJ, Randhawa IAS, Kemp KL, McCue ME, Bertin FR, Stewart AJ.Insulin dysregulation (ID) is central to equine metabolic syndrome. There are limited epidemiological studies investigating dynamic testing of ID in ponies. Objective: To evaluate prevalence and risk factors for ID through dynamic testing of hyperinsulinaemia (DHI) and insulin resistance (IR). Methods: Cross-sectional. Methods: Sex, age, breed, height, cresty neck score (CNS), body condition score (BCS), laminitis, HMGA2:c.83G>A genotype and pituitary pars intermedia dysfunction (PPID) status were documented. Dynamic hyperinsulinaemia was diagnosed with an oral sugar test (OST) and IR with an ...
Ireland JL, Lester A, Banse HE.Measurement of basal adrenocorticotropic hormone (ACTH) concentration is the most commonly used diagnostic test for pituitary pars intermedia dysfunction (PPID). Although several pre-analytical and analytical factors have been reported to affect basal ACTH concentrations in equids, the extent to which these have been evaluated in the context of PPID diagnosis is unclear. The objectives of this scoping review were to identify and systematically chart current evidence about pre-analytical and analytical factors affecting basal ACTH concentrations in adult domestic equids. Systematic searches of ...
de Preux M, Precht C, Guevar J, Graubner C, Thenhaus-Schnabel S, Buser L, Lukes A, Koch C.A 16-year-old warmblood mare was referred with a progressive history of behavioral changes and left-sided blindness. Following neuroanatomical localization to the forebrain, magnetic resonance imaging of the head revealed a well-delineated, 4.5 cm in diameter, round pituitary mass causing marked compression of the midbrain and optic chiasm. Euthanasia was recommended but declined by the owners. Veterinary specialists and a human neurosurgeon collaboratively prepared for surgical case management. A novel navigated transmandibular lateral transsphenoidal approach was developed to access the re...
Waitt Wolker LH, Black A, Lee JK.Clinical and histologic examination of a 12-y-old client-owned Quarter Horse gelding with pituitary pars intermedia dysfunction revealed dermatitis, cellulitis, and osteomyelitis caused by , confirmed by a PCR assay. This novel presentation of a fungal disease in a horse was characterized by aggressive local invasion and failure to respond to all medical therapy attempted over a 1-y period. Treatments included systemic and topical antifungals, anti-inflammatories, and use of cellular matrices. Surgical excision was not attempted but should be strongly considered early in the disease process in...
Sundra T, Kelty E, Rossi G, Rendle D.Dopaminergic agonists are accepted as the most effective treatment for pituitary pars intermedia dysfunction. However, some horses are refractory to daily oral pergolide, the recommended registered treatment. Extended-release cabergoline (ERC) injection may offer an alternative. The objective of this retrospective case series was to describe clinical and endocrinological responses to ERC. Unassigned: Medical records of horses treated with weekly intramuscular injections of ERC (5 mg/mL, BOVA Aus) at either 0.01 mg/kg (high dose, HD) ( = 10) or 0.005 mg/kg (low dose, LD) ( = 30) w...
Giers J, Bartel A, Kirsch K, Müller SF, Horstmann S, Gehlen H.After submaximal exercise, blood values of eventing horses show physiological reactions. This prospective longitudinal study investigated blood parameters in 20 elite eventing horses before and after two-four-star cross-country rides. Using a mixed model adjusting for plasma volume shift, we assessed exercise-dependent parameters and compared blood values with reference ranges for healthy horses at rest. Following exercise, cortisol, triiodothyronine (T3) and thyroxine (T4) showed short-term increases, and superoxide-dismutase showed a small short-term increase. Hepatic values showed short-ter...
Nielsen MK, Finnerty CA, Ripley NE, Page AE, McClendon ME, Adams AA.Anthelmintic performance against equine cyathostomins can be evaluated by two different non-terminal measures; the Fecal Egg Count Reduction Test (FECRT) and the Egg Reappearance Period (ERP). Most available FECRT and ERP data have been determined in populations of young horses, and very little information is available from mature and senior horses. Furthermore, it is unknown how commonly occurring equine endocrine disorders such as Insulin dysregulation (ID) and Pituitary pars intermedia dysfunction (PPID) may interfere with these measurements, but it has been suggested that horses with these...
Horner A, Bamford NJ, Stear MJ, Piedrafita D, Jabbar A, Hughes KJ, El-Hage CM, Preston S.Pituitary pars intermedia dysfunction (PPID) is the most common endocrine disorder of older horses. Immune dysfunction in horses with PPID could increase susceptibility to infectious diseases, including strongyle infections; however, few data are available. The aim of this study was to determine if horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses, over a fourteen-week period in Victoria, Australia. Clinical signs and plasma adrenocorticotropic hormone (ACTH) concentrations were used to categorise horses into PPID (n=14) or control (n=31) groups. Fae...
