Topic:Pituitary Pars Intermedia Dysfunction
Pituitary Pars Intermedia Dysfunction (PPID) is a condition in horses characterized by a dysfunction of the pituitary gland, specifically the pars intermedia. This dysfunction leads to an overproduction of certain hormones, notably adrenocorticotropic hormone (ACTH), which can affect various physiological processes. PPID is commonly diagnosed in older horses and is associated with clinical signs such as hirsutism, laminitis, and changes in body condition. The condition is also referred to as equine Cushing's disease. This page compiles peer-reviewed research studies and scholarly articles that explore the pathophysiology, diagnosis, and management of Pituitary Pars Intermedia Dysfunction in equine populations.
Profiles of pro-opiomelanocortin and encoded peptides, and their processing enzymes in equine pituitary pars intermedia dysfunction. Equine pituitary pars intermedia dysfunction (PPID) is characterized by hyperplasia of the pars intermedia (PI) melanotrophs of the pituitary gland (PG), and increased production of proopiomelanocortin (POMC). POMC is cleaved by prohormone convertase 1 (PC1) to produce adrenocorticotropic hormone (ACTH), and further processing of ACTH by PC2 to produce alpha-melanocyte stimulating hormone (α-MSH) and corticotropin-like intermediate peptide (CLIP). High plasma ACTH concentrations in horses with PPID might be related to reduced conversion of ACTH to α-MSH by PCs. The hypothesis of this study w...
Comparison of two methods for measurement of equine adrenocorticotropin. Accurate measurement of equine adrenocorticotropin (ACTH) is important for the diagnosis of equine pituitary pars intermedia dysfunction (PPID). Several radioimmunoassays (RIAs) and chemiluminescent immunoassays (CIAs) are used for measurement of ACTH concentration in horses; whether these methods yield similar results across a range of concentrations is not determined. We evaluated agreement between a commercial RIA and CIA. Archived plasma samples ( n = 633) were measured with both assays. Correlation between the 2 methods was moderate ( r = 0.49, p < 0.001). Bland-Altman analysis reveale...
Development of two surgical approaches to the pituitary gland in the Horse. Current treatment of equine pituitary pars intermedia dysfunction (PPID) requires daily oral medication. Minimally invasive surgical palliation of this condition is appealing as a single treatment to alleviate the clinical signs of disease, dramatically improving the welfare of the horse. Objective: To develop a surgical approach to the equine pituitary gland, for subsequent treatment of PPID. Methods: A cadaver study to develop methodology and a terminal procedure under anaesthesia in the most promising techniques. Methods: Four surgical approaches to the pituitary gland were investigated in ...
The oral glucose test predicts laminitis risk in ponies fed a diet high in nonstructural carbohydrates. The aim of this study was to investigate the relationship between laminitis development in ponies and insulin/glucose concentrations in response to the oral glucose test (OGT) and a dietary challenge high in nonstructural carbohydrates (NSCs). After undergoing an OGT (1 g dextrose/kg BW in feed), 37 ponies with 2-h serum insulin concentrations ranging from 22 to 1,133 μIU/mL were subjected to a diet challenge period (DCP), consuming 12 g NSC/kg BW/d for up to 18 d. Insulin and glucose responses were measured on day 2 of the DCP. Clinical laminitis was diagnosed by blinded experts and confi...
Effect of dietary carbohydrates and time of year on ACTH and cortisol concentrations in adult and aged horses. Diagnosis of equine pituitary pars intermedia dysfunction (PPID) remains a challenge as multiple factors (stress, exercise, and time of year) influence ACTH and cortisol concentrations. To assess endocrine status in a study designed to evaluate the effects of age and diet on glucose and insulin dynamics, we performed thyrotropin-releasing hormone (TRH) stimulation tests and overnight dexamethasone suppression tests in March, May, August, and October on 16 healthy Thoroughbred and Standardbred mares and geldings. Horses were grouped by age: adult (mean ± SD; 8.8 ± 2.9 yr; n = 8) and aged (20...
Equine pituitary pars intermedia dysfunction: An international survey of veterinarians’ approach to diagnosis, management, and estimated prevalence. The objectives of the present study were to determine if diagnosis and treatment of equine pituitary pars intermedia dysfunction (PPID) vary by geographic region and to report the prevalence of PPID in horses as observed by veterinarians across locations. An online questionnaire was developed for veterinarians who treat horses. Veterinary associations, especially equine specialty subgroups, were contacted and a survey link was sent to members of each organization. Generalized linear models were used to examine whether the method of diagnosis and treatment of this condition, as well as its repo...
Successful medical treatment of an Aspergillus terreus mycetoma of the nostril/lip in a 16-year-old Fjord pony gelding with pituitary pars intermedia dysfunction. Mycetoma is a chronic, proliferative lesion of cutaneous/subcutaneous tissue characterized by draining tracts and granules in the discharge caused by actinomycetes (actinomycetoma) or filamentous fungi (eumycotic mycetoma). Objective: This case report describes the unusual finding of a cutaneous mycetoma of the lateral wing of the right nostril in a gelding. Methods: A 16-year-old Fjord gelding with suspected pituitary pars intermedia dysfunction (PPID) was presented for evaluation of a nonpainful, firm and raised mass involving the lateral wing of the right nostril and the lip. Results: Cytol...
Therapeutics for Equine Endocrine Disorders. Equine endocrine disease is commonly encountered by equine practitioners. Pituitary pars intermedia dysfunction (PPID) and equine metabolic syndrome (EMS) predominate. The most logical therapeutic approach in PPID uses dopamine agonists; pergolide mesylate is the most common. Bromocryptine and cabergoline are alternative drugs with similar actions. Drugs from other classes have a poor evidence basis, although cyproheptadine and trilostane might be considered. EMS requires management changes as the primary approach; reasonable justification for use of drugs such as levothyroxine and metformin m...
Occurrence of primary lymphocytic hypophysitis in two horses and presence of scattered T-lymphocytes in the normal equine pituitary gland. The postmortem examination of a 14-y-old Appaloosa gelding with clinically diagnosed pituitary pars intermedia dysfunction showed a unique finding of moderate multifocal lymphocytic hypophysitis (LH). The pituitary glands of 24 horses submitted for postmortem examination were examined grossly and examined histologically for the presence of lymphocytes. Of these 23 horses, 1 additional case suffered from moderate LH. The 2 cases with LH tested negative for Equid herpesvirus 1 and 4 by polymerase chain reaction and immunohistochemistry (IHC), and no viral particles were observed by electron micr...
Measurement of cortisol concentration in the tears of horses and ponies with pituitary pars intermedia dysfunction. OBJECTIVE To compare tear cortisol concentrations between horses and ponies with pituitary pars intermedia dysfunction (PPID) and healthy nonaged (≤ 15 years old) and aged (≥ 20 years old) horses and to determine whether serum and tear cortisol concentrations were correlated. ANIMALS 11 horses and ponies with PPID and 20 healthy control horses and ponies (11 nonaged and 9 aged). PROCEDURES Paired tear and serum samples were obtained from PPID and control animals. All animals were free of active ocular disease. Tear and serum cortisol concentrations were measured with an ELISA and chemilumi...
Effects of Common Equine Endocrine Diseases on Reproduction. Endocrine diseases, such as equine metabolic syndrome and pituitary pars intermedia dysfunction, are common in domesticated horse populations, and the frequency with which these diseases are encountered and managed by equine veterinary practitioners is expected to increase as the population ages. As clinicians learn more about the effects of these diseases on equine reproductive physiology and efficiency (including effects on reproductive seasonality, ovulation efficiency, implantation, early pregnancy loss, duration of pregnancy, and lactation), strategies and guidelines for improving fertili...
Musculoskeletal Disease in Aged Horses and Its Management. Musculoskeletal disorders are the most prevalent health problem in aging horses. They are not life threatening, but are painful and an important welfare issue. Chronic joint disease (osteoarthritis) and chronic laminitis are the most prevalent. Treating osteoarthritis in the elderly horse is similar to treating performance horses, but aims at providing a stable situation with optimal comfort. Immediate medical treatment of flare-ups, long-term pain management, and adaptation of exercise and living conditions are the mainstays of treatment. Laminitis in the geriatric horse is related often to p...
Endocrine Disease in Aged Horses. Aging horses may be at particular risk of endocrine disease. Two major equine endocrinopathies, pituitary pars intermedia dysfunction and equine metabolic syndrome, are commonly encountered in an aging population and may present with several recognizable signs, including laminitis. Investigation, treatment, and management of these diseases are discussed. Additionally, aging may be associated with development of rarer endocrinopathic problems, often associated with neoplasia, including diabetes mellitus and other confounders of glucose homeostasis, as well as thyroid, parathyroid, and adrenal d...
Effects of anesthesia with isoflurane on plasma concentrations of adrenocorticotropic hormone in samples obtained from the cavernous sinus and jugular vein of horses. OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses. ANIMALS 6 clinically normal adult horses. PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and ane...
Effects of withholding feed on thyrotropin-releasing hormone stimulation test results and effects of combined testing on oral sugar test and thyrotropin-releasing hormone stimulation test results in horses. OBJECTIVE To assess effects of withholding feed on thyrotropin-releasing hormone (TRH) stimulation test results used in diagnosis of pituitary pars intermedia dysfunction in horses and determine effects of combined testing on results of the TRH stimulation test and the oral sugar test (OST) used in diagnosis of equine metabolic syndrome. ANIMALS 30 adult horses. PROCEDURES All horses underwent TRH stimulation tests under fed and nonfed conditions, an OST alone, and an OST combined with TRH stimulation testing. For TRH stimulation tests, plasma ACTH concentrations were measured before (baseline...
Integumentary Disorders Including Cutaneous Neoplasia in Older Horses. Few skin diseases specifically or exclusively affect older horses and donkeys. Hypertrichosis (hirsutism) associated with pituitary pars intermedia dysfunction is probably the most recognized and best understood exception and is the most common age-related skin condition in equids. Many other conditions are known to be more serious in older horses. Horses affected with immune-compromising conditions can be more severely affected by infectious diseases of the skin or heavy and pathologically significant parasitism. Neoplasia of the skin is probably more prevalent and worse in older horses, alth...
Pharmacokinetic and pharmacodynamic properties of pergolide mesylate following long-term administration to horses with pituitary pars intermedia dysfunction. The objective of this study was to gain an understanding of the pharmacokinetic and pharmacodynamic properties of pergolide in horses with PPID after of long-term oral administration. Six horses with confirmed PPID were treated with pergolide (Prascend ) at 1Â mg/horse po q24Â h for 2Â months, followed by 2Â mg/horse po q24Â h for 4Â months. Following the last dose, plasma samples were collected for measurement of pergolide using an LC/MS/MS method and ACTH measurement using a chemiluminescent immunoassay. Noncompartmental and compartmental pharmacokinetic analyses were performed, as well as p...
Effect of Age, Season, Body Condition, and Endocrine Status on Serum Free Cortisol Fraction and Insulin Concentration in Horses. Increased free cortisol fraction is associated with insulin dysregulation (ID) in people with Metabolic Syndrome and Cushing's Disease. Free cortisol has not been investigated in equine endocrine disorders. Objective: (1) In healthy horses, sex, age, body condition score (BCS), and season impact free cortisol; (2) free cortisol is increased in horses with Pituitary Pars Intermedia Dysfunction (PPID) or Equine Metabolic Syndrome (EMS). Methods: Fifty-seven healthy horses; 40 horses and ponies with PPID (n = 20) or EMS (n = 20). Methods: Prospective study. Serum collected seasonally from healthy...
Pituitary pars intermedia dysfunction (equine Cushing’s disease) in a Thoroughbred stallion: a single report. Equine pituitary pars intermedia dysfunction (PPID) generally occurs in older horses showing hirsutism, delayed molting, weight loss, polydipsia, polyuria, laminitis, and reproductive disorders (in broodmares), but there have been no reports on stallions. This report presents a case of a 21-year-old Thoroughbred stallion that developed hirsutism and experienced delayed molting. There were no abnormal findings for semen quality or the stallion's sexual desire. The horse was diagnosed with PPID based on dexamethasone suppression test and plasma levels of adrenocorticotropic hormone. It was then ...
Age-related Qualitative Histological and Quantitative Stereological Changes in the Equine Pituitary. The aim of this study was to characterize the age-related morphological changes in the equine pituitary and to identify features that allow distinction between pituitary pars intermedia dysfunction (PPID)-associated and non-functional/age-associated pars intermedia (PI) adenoma. Pituitary glands of all horses submitted for necropsy examination at the Institute of Veterinary Pathology, Ludwig Maximilians University Munich, between 2008 and 2012 were examined. The pituitary glands of 124 horses were weighed, cut into ∼2 mm slices and examined histologically. A slightly modified grading scheme...
Comparison of corneal degeneration and calcific band keratopathy from 2000 to 2013 in 69 horses. To compare signalment, presentation, treatment, and outcome in horses diagnosed with corneal degeneration (CD) or calcific band keratopathy (CBK) at a referral hospital. Methods: Sixty-nine horses (87 eyes) diagnosed with either CD or CBK. Methods: Medical records of horses diagnosed with CD or CBK at the University of California-Davis Veterinary Medical Teaching Hospital (UCD-VMTH) between 2000 and 2013 were reviewed. Signalment, concurrent ophthalmic diagnoses, previous therapies, diagnostic tests, systemic diagnoses, treatment, follow-up, and outcomes were compared between horses diagnosed ...
[Reference ranges of insulin, insulin like growth factor-1 and adrenocorticotropic hormone in ponies]. The aim of this study was to validate a chemiluminescence immunometric assay using the IMMULITE 2000® for the determination of adrenocorticotropic hormone (ACTH), insulin and insulin-like growth factor-1 (IGF-1) from which reference ranges were calculated for ponies. Methods: Blood samples of 130 ponies aged 3-32 years were collected in the afternoon. The reference ranges were calculated according to the Guideline EP28-A3C of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) from 2010. Results: The determined intraday precision for insulin was 3.28%, for ACTH 3...
Initial analytic quality assessment and method comparison of an immunoassay for adrenocorticotropic hormone measurement in equine samples. Equine pituitary pars intermedia dysfunction (PPID) may be diagnosed by measuring baseline plasma adrenocorticotrophic hormone (ACTH). The Immulite 1000 analyzer uses an automated chemiluminescence enzyme assay, previously validated for measuring equine ACTH. Recently, an automated bench-top immunoassay analyzer (AIA-360), designed for analytes in people, became available for veterinary use. Objective: Objectives were to evaluate analytic performance of the AIA immunoassay for measuring equine ACTH, and compare the results with those obtained by the Immulite. Methods: Adrenocorticotrophic horm...
What’s New in Old Horses? Postmortem Diagnoses in Mature and Aged Equids. Postmortem findings in 241 equids admitted to a teaching hospital that were at least 15 years old at autopsy were reviewed (1) to determine disease prevalence, (2) to compare the cause of death (or euthanasia) in equids 15 to 19 years of age (n = 116) with that in equids ≥20 years of age (n = 125), and (3) to catalog coexisting lesions in equids with pituitary pars intermedia dysfunction (PPID). Breed and sex were evenly distributed between the age groups. Death or euthanasia was attributed to disease of the digestive system (41.5%), pituitary gland (12.9%), locomotor system (10.0%), nervous...
Equine pituitary pars intermedia dysfunction: current perspectives on diagnosis and management. Equine pituitary pars intermedia dysfunction (PPID) is a neurodegenerative disease of the hypothalamus, resulting in the loss of dopaminergic inhibition of pars intermedia. An oxidative stress injury of unknown etiology has been suggested to initiate the neurodegeneration. While hypertrichosis (formerly known as hirsutism) is considered pathognomic for advanced disease, the antemortem diagnosis of subclinical and early disease has continued to prove difficult. Numerous tests have been used with varying sensitivities and specificities. The overnight dexamethasone suppression test, originally do...
Treatment of equine metabolic syndrome: A clinical case series. Treatment of equine metabolic syndrome (EMS) is essential to improve insulin sensitivity and reduce the risk of laminitis. Calorie restriction and increased exercise are the mainstays of treatment but there is potential for poor owner compliance. Objective: To determine whether significant weight loss accompanied by improvements in measures of insulin sensitivity can be achieved in horses and ponies with EMS managed by their owners in their normal environment under veterinary guidance. Methods: Retrospective clinical case series. Methods: Horses and ponies attending 2 university hospitals for ...
Lamellar pathology in horses with pituitary pars intermedia dysfunction. Hoof lamellar pathology in horses with pituitary pars intermedia dysfunction (PPID) has not been described previously. Objective: To describe the histomorphometry and pathological lesions in hoof lamellar tissue of animals that had PPID with or without concurrent laminitis, with reference to age-matched controls. We hypothesised that lamellar lesions consistent with laminitis would be associated with PPID, even in animals without current or historical laminitis. Methods: Prospective case-control study. Methods: Mid-dorsal hoof histological sections were obtained post mortem from the forelimbs ...
Design of an endovascular morcellator for the surgical treatment of equine Cushing’s disease. A new paradigm of surgical treatment of equine Cushing's disease has been developed using the vascular system combined with a flexible morcellation instrument to reach the pituitary gland. Objective: The goal was twofold: (1) to design, prototype, and test an instrument that can reach the pituitary gland using the vascular system unique to equids and (2) to test the feasibility of the endovascular approach. Methods: The morcellator consists of a radial rotating cutting blade for tissue resection, a flexible shaft incorporating a cable drive for flexible actuation, and central morcellated tissu...
Neutrophil function in healthy aged horses and horses with pituitary dysfunction. Immunosuppression leading to opportunist bacterial infection is a well-recognized sequela of equine pituitary pars intermedia dysfunction (PPID). The mechanisms responsible for immune dysfunction in PPID however, are as of yet poorly characterized. Horses with PPID have high concentrations of hormones known to impact immune function including α-melanocyte stimulating hormone (α-MSH) and insulin. α-MSH and related melanocortins have been shown in rodents and people to impair neutrophil function by decreasing superoxide production (known as oxidative burst activity), migration and adhesion. T...