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.
Viviani P, Ragno VM, Parker S, Montgomery JB.Endocrine disorders in horses, such as pituitary pars intermedia dysfunction and equine metabolic syndrome, rely on hormone testing for diagnosis, but seasonal and regional variabilities highlight the need for locally generated data. Objective: To characterize monthly blood concentrations of ACTH and insulin over 1 year in healthy horses in Saskatchewan. A secondary objective was to assess the association between these outcomes and the following factors: sex, age, breed, pregnancy status, level of exercise, body condition score, and cresty neck score. Methods: Sixty-eight clinically healthy, c...
Billmann P, Durham A, Christen G, Savioli G, Gross JJ, Gerber V, Fouché NE.Limited published data are available regarding the relationships among clinical signs associated with pituitary pars intermedia dysfunction (PPID), age, and concentrations of proopiomelanocortin-derived peptides and cortisol. Objective: Identify clinical signs associated with age, beta-endorphin (β-END), adrenocorticotropic hormone (ACTH), and cortisol concentrations and compare β-END and cortisol concentrations between horses with PPID and geriatric controls. Methods: A total of 113 horses aged 18-32 years. Methods: Cross-sectional study. Clinical signs were scored, plasma β-END, ACTH, an...
Teague P, Dark M, Verdugo D, Freeman D, McFarlane D.The equine pancreas remains understudied, particularly in the context of endocrine disease. This study aimed to characterize regional islet distribution and composition in the normal equine pancreas and investigate how hyperinsulinemia (HI) and pituitary pars intermedia dysfunction (PPID) influence pancreatic islet morphology and hormone expression. In the first experiment, pancreas samples from eight healthy horses were collected and analyzed across three anatomical locations: left lobe, body, and right lobe. The left lobe exhibited a greater relative islet area and perimeter compared to the ...
Stapley E, Gillespie-Harmon C, Waxman S, Farr A, Bertin FR.The frequency of comorbidities in horses with pituitary pars intermedia dysfunction (PPID) in first-opinion practice is unknown. It is hypothesized that horses with PPID would have more frequent medical events and be euthanized at a younger age. Unassigned: This was a case-control retrospective study. Medical records ranging from 1996 to 2024 including 132 horses diagnosed with PPID and 274 controls matched by age and breed were reviewed. Variables associated with PPID were evaluated with a Fisher exact or Mann-Whitney U test followed by conditional logistic regression. Results were reported a...
Fouché N, Howard J, Gerber V, Billmann P, Farinha do Sul M, Christen G, Bruckmaier R, Philipona C, Schmutz NB, Gross J.β-endorphin, a proopiomelanocortin (POMC)-derived peptide secreted by pars intermedia melanotropes, may play a significant but underexplored role in pituitary pars intermedia dysfunction (PPID) pathophysiology and diagnosis. This study aimed to (1) validate a commercially available human β-endorphin enzyme-linked immunosorbent assay (ELISA) kit for equine samples, and (2) compare β-endorphin concentrations between horses with PPID and healthy controls. Assay validation included the generation of standard curves using purified synthetic equine β-endorphin and human β-endorphin standards, w...
Parmantier S, Kyriazopoulou P, McClendon M, Adams A, Murphy BA.Fifty-two horses aged >15 years, diagnosed with pituitary pars intermedia dysfunction (PPID), and displaying hypertrichosis were recruited via an online survey of PPID horse owners. From mid-December, group T ( = 29) wore Equilume light masks extending photoperiod to 15 h daily, while group C1 ( = 23) remained under natural photoperiod. As 85% (44/52) of recruited study horses received pergolide medication, a second unmedicated PPID research herd (C2; = 17) was recruited and remained under natural photoperiod. Hair coat samples, shedding and body condition scores were collected monthly by own...
Menzies-Gow NJ.Pituitary pars intermedia dysfunction (PPID) is a common, slowly progressive, neurodegenerative disorder of the older horse. Oxidative damage to the hypothalamic periventricular neurons results in loss of dopaminergic inhibition of the pars intermedia region of the pituitary gland. Consequently, there is increased production of the pro-opiomelanocortin (POMC)-derived hormones normally produced by this region, as well as initial melanocyte hypertrophy and hyperplasia, followed by adenomatous change. Clinical signs that are highly suggestive of the disease are generalised and regional hypertrich...
Murase H, Wachi S, Matsuyama R, Makita K, Sato F.Pituitary pars intermedia dysfunction (PPID) is an age-related disease considered to have a negative impact on fertility. To understand the true impact of PPID on fertility, the influence of age must be considered. Objective: This study aimed to assess the impact of PPID on fertility while accounting for the effect of aging. Methods: A total of 332 Thoroughbred mares aged 10-20 years and managed across 137 private farms in Hidaka, Hokkaido, Japan were classified as PPID, equivocal, or non-PPID based on plasma adrenocorticotropic hormone concentration in 2019 and 2020. The prevalence of PPID an...
Tretow M, Hain AM, Bienert-Zeit A.The dental syndrome EOTRH is a painful, progressive dental disease with an unknown aetiology. The often painful nature of EOTRH emphasises the need for a better knowledge of the underlying pathogenic mechanism and risk factors. A comparative analysis of haematological, biochemical and endocrine values in EOTRH-affected and non-affected horses has not been described. Objective: To compare haematological, biochemical, and endocrine parameters in EOTRH-affected and non-affected horses to detect risk factors for horses developing EOTRH. Methods: Cross sectional. Methods: Blood samples of 154 Icela...
Osorio-Cardona JJ, Usuga-Moreno VM, Martínez-Aranzales JR.The dexamethasone suppression test (DST) has been used in humans for the diagnosis of psychiatric problems such as depression, anxiety and Cushing's syndrome, and in horses for the ante mortem diagnosis of dysfunction of the intermediate part of the pituitary. Objective: This study aimed to examine the functionality of the hypothalamic-pituitary-adrenal axis through the DST and the cortisol index (CI), to evaluate the rhythmicity of the circadian cycle of cortisol in healthy horses with crib-biting or windsucking. Methods: A total of 20 Colombian Creole horses of both sexes, under similar mana...
Schott HC, Strachota JR, Marteniuk JV, Refsal KR.Limited data document long-term responses of equids with pituitary pars intermedia dysfunction (PPID) to pergolide treatment. Objective: Report clinical response, medical problems, outcome, and owner satisfaction with pergolide treatment of PPID-affected equids over 14 years. Methods: Thirty client-owned equids with PPID. Methods: After completion of an open field clinical efficacy study for Prascend® (pergolide tablets), 28 horses and two ponies were enrolled in an extended treatment study (13 receiving 2 μg/kg PO q24h and 17 receiving 4 μg/kg PO q24h). Clients were interviewed eve...
Bouquet A, Nicol C, Knowles EJ, Schofield I, Menzies-Gow NJ.Clinical signs of pituitary pars intermedia dysfunction (PPID) are frequently mistaken for 'normal' ageing and may not be optimally assessed. Objective quality of life (QoL) assessment could improve clinical decision-making. Objective: To develop an owner-reported health-related quality-of-life (HRQoL) assessment tool for equines with PPID. To assess factors associated with HRQoL scores. Methods: Quantitative, cross-sectional study. Methods: HRQoL tool development followed a standard psychometric process of item (any aspect of PPID and its management that could impact QoL) identification (foll...
Davis EL, Wood AD, Potier JFN.Prevalence of endocrine disease in sport horses has been sparsely reported. They often compete well into their teenage years; thus, diagnosis and control of endocrine disease could be important to maintain performance and optimise health and welfare. The aim was to compare the prevalence of pituitary pars intermedia dysfunction (PPID), insulin dysregulation (ID) and metabolic obesity between sport and non-sport type breeds and assess disease progression. Blood samples submitted for plasma adrenocorticotropic hormone (ACTH), serum insulin or adiponectin were included in this study. Horses were ...
Stapley ED, Bertin FR.Pituitary pars intermedia dysfunction is diagnosed using immunoreactive ACTH concentrations. Glass reportedly binds ACTH, but the clinical relevance of using glass blood tubes for measuring equine ACTH concentrations is controversial. This study investigates whether the collection of whole blood into glass EDTA tubes and storage for up to 6 hours changes ACTH concentrations compared to plastic EDTA tubes. Unassigned: This was a cohort study. Whole blood was collected into both glass and plastic EDTA tubes from 9 horses > 12 years of age, including 4 with pituitary pars intermedia dysfunction a...
Fouché N, Doras C, Schüpbach-Regula G, Scherer A, Freudenschuss B, Gerber V.There remains a scarcity of data concerning the relationship between the clinical signs associated with PPID and plasma ACTH concentrations. Objective: Report the frequency of clinical signs in the study cohort and identify individual clinical signs or combinations of clinical signs associated with high ACTH concentrations. Methods: Two hundred eighty equids were examined by private veterinarians. Methods: A cross-sectional study of animals with clinical suspicion of PPID was conducted between August and November. Private practitioners completed an online questionnaire reporting detailed infor...
Galinelli NC, Bamford NJ, Erdody ML, Mackenzie SA, Warnken T, Harris PA, Sillence MN, Bailey SR.Due to the high frequency of laminitis reported for both conditions, the relationship between pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID), and the potential role of dopamine in modifying insulin secretion, requires further investigation. Objective: To evaluate the effect of pergolide mesylate on insulin sensitivity and postprandial insulin and glucose responses in horses and ponies with ID, both with or without concurrent PPID. Methods: Randomised crossover study. Methods: Sixteen horses and ponies, comprising eight matched pairs (PPID+ID or ID-only), were given...
Johnston TJ, Stewart AJ, Dryburgh EL, Bertin FR.Pituitary pars intermedia dysfunction (PPID) is diagnosed by measuring the ACTH concentrations. Due to the reported instability of ACTH, it is recommended to transfer centrifuged plasma into cryovials; however, in practice, cryovials are infrequently used, and serum (red-top) tubes are used instead. This study investigated whether this procedure affects ACTH concentrations and the diagnosis of PPID. Unassigned: This was a cohort study. Blood was collected into EDTA tubes from 9 horses with PPID and 7 controls. After centrifugation, plasma was either aliquoted into a cryovial or into a serum tu...
Wang W, Gibson J, Horsman S, Mikkelsen D, Bertin FR.Altered gut microbiota has been associated with dopaminergic degenerative diseases in people, but studies on horses with pituitary pars intermedia dysfunction (PPID) are lacking. Objective: Investigate the effect of PPID on fecal microbiota in horses. Methods: Nine horses with PPID and 13 age-matched control horses. Methods: Prospective control study. Fecal samples were collected bimonthly. Microbial analysis used 16S rRNA sequencing to determine the relative abundance at genus and phylum levels, assess alpha and beta diversity and identify core microbiota. Results: Horses with PPID had decrea...
Maier I, Kienzle E.The goal of this meta-analysis was to (i) identify any potential differences in the apparent and true digestibility, renal excretion, and retention between ponies and horses and (ii) examine the impact of work on these parameters. Additionally, the study aimed to (iii) evaluate the effects of water deficiency. This meta-analysis used data from 33 studies and plotted them in diagrams similar to the Lucas test against mineral intake. Three studies involved ponies that were later diagnosed with pituitary pars intermedia dysfunction (PPID). These were compared with other data to identify quantitat...
Jargielo MM, Kritchevsky JE, Bertin FR.Pergolide, labeled for the treatment of pituitary pars intermedia dysfunction, is 90% protein bound and might cause a decrease in blood thyroid hormone concentrations by displacing them from binding proteins. This study investigated the effect of pergolide on the equine thyroid function. Methods: This was an analytic, observational, cohort study. Six horses (17 to 24 years old and 530 to 599 kg) received 1 mg of pergolide mesylate orally once a day from days 1 to 6. Total T4 (tT4) was measured daily from day 0 to 11 (before, during, and after pergolide treatment). Thyrotropin-releasing hormone...
Cash CM, de Laat MA.The melanocortin 2 receptor (MC2R) has relevance to equine pituitary pars intermedia dysfunction (PPID), as it is the primary binding site for ACTH, which circulates at elevated concentrations in animals affected by PPID. Despite this, little is known about MC2R in equine species. The overall aim of this investigation was to determine MC2R mRNA expression in tissues relevant to PPID in healthy horses and to examine the MC2R gene sequence in a cohort of horses and ponies with and without PPID. The study found that the MC2R gene was expressed in both adrenal and pituitary gland tissues as report...
Galinelli NC, Bamford NJ, Erdody ML, Warnken T, de Laat MA, Sillence MN, Harris PA, Bailey SR.The role of dopamine in the regulation of insulin secretion in horses is poorly understood and requires further investigation. Pituitary pars intermedia dysfunction (PPID) is associated with decreased activity of dopaminergic neurons which normally suppress peptide hormone secretion from the pituitary pars intermedia. A high proportion of horses with PPID also have insulin dysregulation (ID), characterised by post-prandial hyperinsulinaemia and/or tissue insulin resistance, which are risk factors for the development of laminitis. The aim of this study was to investigate the effects of alpha-me...
Neufang L, Ramos J, Eda S, Flatland B, Giori L.Pituitary pars intermedia dysfunction (PPID) is a neurodegenerative disease of senior horses. Loss of dopaminergic inhibition of the melanotropes of the pars intermedia leads to increased concentrations of pro-opiomelanocortin (POMC)-derived peptides. Diagnosis is challenging due to pre-analytical variables, such as sample storage, handling, and time to analysis. Our objective was to develop an ELISA for ACTH measurement, which could ultimately form the basis for a stall-side equine ACTH test. We selected 2 ACTH-specific monoclonal antibodies, CBL57 and EPR20361-248, based on the recognition o...
Herbst AC, Coleman MC, Macon EL, Harris PA, Adams AA.Information on health care and health status of U.S. senior horses (≥15 years of age) is currently sparse. Objective: (A) Provide an overview of owner-reported (1) medical conditions, (2) management/treatment practices for equine metabolic syndrome and pituitary pars intermedia dysfunction (PPID), (3) frequencies of routine health care practices and (4) supplement and pharmaceutical use in U.S. senior horses (≥15 years of age). (B) Evaluate potential risk factors for certain medical conditions and for low routine health care. Methods: Online survey. Methods: Descriptive and inferential...
Hallowell KL, Dembek K, Horne CR, Knych HK, Messenger KM, Schnabel LV.Steroid-associated laminitis remains a major concern with use of corticosteroids in horses. Individual case factors such as joint pathology, pre-existing endocrinopathies, or corticosteroid type, dose, and timing influencing steroid-induced laminitis risk have not been investigated. This study aimed to determine if systemic absorption of triamcinolone acetonide (TA) varies between intrasynovial (antebrachiocarpal) and extrasynovial (sacroiliac) injection sites, and to determine the effects of TA absorption on glucose, insulin, cortisol, and adrenocorticotropic hormone (ACTH). Twenty adult hors...
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...
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...
Frank N, Tadros EM.Abnormalities of insulin metabolism include hyperinsulinaemia and insulin resistance, and these problems are collectively referred to as insulin dysregulation in this review. Insulin dysregulation is a key component of equine metabolic syndrome: a collection of endocrine and metabolic abnormalities associated with the development of laminitis in horses, ponies and donkeys. Insulin dysregulation can also accompany prematurity and systemic illness in foals. Causes of insulin resistance are discussed, including pathological conditions of obesity, systemic inflammation and pituitary pars intermedi...
Brosnahan MM, Paradis MR.To describe the demographic and clinical characteristics of a population of geriatric horses. Methods: Retrospective study. Methods: 467 horses that were > or = 20 years of age. Methods: Medical records of 539 geriatric horses that were evaluated at a university large animal hospital between 1989 and 1999 were reviewed. Data collected included signalment, reason for evaluation, specific diagnoses, surgical procedures, inpatient or outpatient care, duration of hospitalization, and outcome. Results: 467 horses met the criteria for inclusion in the study. Horses that were > or = 20 years of age c...
McGowan TW, Pinchbeck GP, McGowan CM.Equine pituitary pars intermedia dysfunction (PPID) is an ageing-related neurodegenerative disorder. The prevalence and risk factors for PPID using seasonally adjusted basal adrenocorticotropic hormone (ACTH) concentrations in aged horses have not been previously reported. Objective: To determine the prevalence, risk factors and clinical signs predictive for PPID in a population of horses aged ≥ 15 years in Queensland, Australia. Methods: Owner-reported data was obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners were visited and a veterina...
Karikoski NP, Horn I, McGowan TW, McGowan CM.Endocrinopathic causes of laminitis may be a common underlying causative pathogenesis in first-opinion or field cases presenting with laminitis, as opposed to laminitis produced in inflammatory research models. This study aimed to determine whether evidence of an underlying endocrinopathy was present in horses presented for laminitis to a first-opinion/referral veterinary teaching hospital. A second aim was to compare the signalment of horses and ponies with laminitis with the equine hospital population during the same period. All horses presenting for laminitis at Helsinki University Equine T...
McFarlane D.Equine pituitary pars intermedia dysfunction (PPID), also known as equine Cushing's syndrome, is a widely recognized disease of aged horses. Over the past two decades, the aged horse population has expanded significantly and in addition, client awareness of PPID has increased. As a result, there has been an increase in both diagnostic testing and treatment of the disease. This review focuses on the pathophysiology and clinical syndrome, as well as advances in diagnostic testing and treatment of PPID, with an emphasis on those findings that are new since the excellent comprehensive review by Sc...
Perkins GA, Lamb S, Erb HN, Schanbacher B, Nydam DV, Divers TJ.Plasma ACTH levels have been variable in horses with a positive clinical response for therapy for equine Cushing's Disease (ECD). Therefore, our purpose was to determine the value of monitoring plasma adrenocorticotropin (ACTH) levels during treatment of equine Cushing's disease (ECD) with either cyproheptadine (n = 32) or pergolide (n = 10). First, we validated the chemiluminescent ACTH assay (specificity, precision, accuracy, intra-assay and interassay variations) and tested methods of handling the whole blood from the time of collection to when the ACTH was assayed. The sensitivity and spec...
Hart KA, Wochele DM, Norton NA, McFarlane D, Wooldridge AA, Frank N.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...
Meier AD, de Laat MA, Reiche DB, Pollitt CC, Walsh DM, McGree JM, Sillence MN.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...
Horn R, Bamford NJ, Afonso T, Sutherland M, Buckerfield J, Tan RHH, Secombe CJ, Stewart AJ, Bertin FR.Pituitary pars intermedia dysfunction (PPID) is a commonly described endocrine disorder in higher latitudes of the Northern hemisphere but the description of the disease at lower latitudes and in the Southern hemisphere is limited. Objective: Document the clinical features of PPID at different Australian latitudes and climates, and investigate factors associated with survival, laminitis and insulin dysregulation (ID). Methods: Retrospective study of 274 equids from eight institutions across Australia. Methods: A diagnosis of PPID was based on endogenous ACTH, overnight dexamethasone suppressio...
McFarlane D, Dybdal N, Donaldson MT, Miller L, Cribb AE.Equine pituitary pars intermedia dysfunction (PPID) is a spontaneously occurring progressive disease affecting aged horses and ponies. The pathogenesis of PPID is poorly understood, but the available evidence supports a loss of dopaminergic inhibition of the melanotropes of the pars intermedia. Horses with PPID have increased plasma concentrations of pars intermedia pro-opiomelanocortin-derived peptides that decrease in response to dopamine or dopamine agonist administration. Dopamine and dopamine metabolite concentrations are decreased in the pars intermedia of affected horses compared to age...
Copas VE, Durham AE.Pituitary pars intermedia dysfunction (PPID) is a common endocrinopathy, frequently diagnosed via plasma adrenocorticotropic hormone (ACTH) concentrations. Seasonal variation in plasma ACTH concentrations has been described in normal horses prompting caution in diagnosing PPID at certain times of the year. The aims of this study were to determine appropriate reference intervals for equine plasma ACTH throughout the year; and to examine the circannual variation of plasma ACTH concentrations in PPID cases. Objective: Plasma ACTH can be used as a test for PPID throughout the year with the use of ...
Ireland JL, McGowan CM.Pituitary pars intermedia dysfunction (PPID) is caused by an age-related degenerative disease of dopaminergic neurones. Despite its importance in equine practice, available information regarding its epidemiology is limited. This systematic review aimed to assess published literature to evaluate available evidence regarding the clinical presentation, prevalence and risk factors for PPID in horses and ponies. Electronic database searches were undertaken using a range of terms, and English language publications published prior to August 2016 were included. Both authors independently reviewed scre...
Couëtil L, Paradis MR, Knoll J.Pituitary adenomas are commonly reported in older horses. The typical clinical signs associated with this condition, also known as equine Cushing's disease (ECD), are related to increased adrenocorticotropin (ACTH) production resulting in hyperadrenocorticism. The primary purpose of this study was to determine whether plasma ACTH concentrations differed between cushingoid and healthy horses. The second objective was to determine the effects of blood sample handling techniques on ACTH concentrations. A commercial human ACTH radioimmunoassay (RIA) was used to quantify equine plasma ACTH. Intra-a...
van Weeren PR, Back W.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...
Cordero M, Brorsen BW, McFarlane D.Cosinor analysis was used to evaluate whether pituitary and adrenal hormones exhibit circadian rhythmicity in horses. The effect of season and animal age on their respective rhythms was also determined. In addition, the usefulness of evaluating cortisol rhythmicity for the diagnosis of pituitary pars intermedia dysfunction (PPID) was assessed. Serum cortisol concentrations (P < 0.01), but not plasma ACTH or α-melanocyte-stimulating hormone (α-MSH), showed a significant circadian periodicity in horses. An effect of season on hormone concentration was observed with plasma ACTH and α-MSH co...
Tadros EM, Fowlie JG, Refsal KR, Marteniuk J, Schott HC.Hyperinsulinaemia is the suspected component of insulin dysregulation having the strongest association with laminitis and occurs variably in equids with pituitary pars intermedia dysfunction (PPID). Objective: We hypothesised that magnitude of hyperinsulinaemia correlates with laminitis severity in PPID-affected equids. Furthermore, we hypothesised that owners can be unaware of chronic endocrinopathic laminitis. Methods: Cross-sectional study. Methods: Serum insulin concentrations, owner-reported laminitis history and radiographic evidence of laminitis were determined in 38 client-owned horses...
Morgan RA, McGowan TW, McGowan CM.To determine the prevalence of hyperinsulinaemia in a population of ponies in Queensland, Australia, and identify associated factors. Methods: Breeders or traders of ponies within a 100 km radius of Gatton, Queensland, were recruited for study using an internet database. Clinical and management details were obtained, including body condition score, fat deposition and history or evidence of laminitis. Blood samples were analysed for serum insulin and triglyceride concentrations and plasma adrenocorticotrophic hormone (ACTH) and leptin concentrations following short-term removal from pasture and...
Miller MA, Moore GE, Bertin FR, Kritchevsky JE.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...
Johnson PJ, Wiedmeyer CE, Messer NT, Ganjam VK.There is growing recognition that obesity is common and represents a significant detriment to the health of companion animals in a manner similar to that by which it is affecting the human population. As is the case for other species, obesity appears to promote insulin resistance in horses and it is through this pathophysiological process that many of the adverse medical consequences of obesity are being characterized. Equine medical conditions that have been described in the context of obesity and insulin resistance differ from those in humans. Chronic human conditions that have been attribut...
McFarlane D.Parkinson's disease (PD) is a leading cause of neurologic disability in the aged population. Remarkable progress has been made in the past decade to understand the cellular and molecular events that occur in PD. However attempts to unravel the early, initiating factors in the pathogenesis of dopaminergic neurodegeneration and PD have been limited by the lack of a suitable animal model. Models in which there has been genetic or environmental manipulation are not of use in determining the natural cause of a disease. While a large scale prospective human study would be ideal, the relatively low p...
Wylie CE, Collins SN, Verheyen KL, Newton JR.Laminitis is a highly debilitating disease of the foot known to have a complex and multifactorial aetiology of metabolic, inflammatory, traumatic or vascular origin. The disease has major welfare implications due to unrelenting pain associated with degenerative changes, which often necessitate euthanasia on welfare grounds. Despite this, there have been few high-quality studies investigating risk factors for equine laminitis, and only a limited number of risk factors have been previously investigated. The aim of this study was to conduct a case-control study of risk factors for active episodes...
Schott HC.PPID in older equids has become a major health concern of horse owners. In response, equine practitioners have made greater efforts at understanding, diagnosing, and treating this disorder. Although PPID is recognized to be a different form of pituitary-dependent hyperadrenocorticism than is seen in canine or human patients, relatively little is known about the pathophysiology and natural progression of the disease. At present, the diagnosis is best supported by manifestation of characteristic clinical signs and endocrinologic test results, preferably a supportive DST result. Treatment must fo...
Mc Gowan TW, Pinchbeck GP, Mc Gowan CM.The sensitivity and specificity of basal plasma α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH) for the diagnosis of pituitary pars intermedia dysfunction (PPID) has not been evaluated in a population-based study. Objective: To evaluate basal plasma α-MSH and ACTH concentrations for the diagnosis of PPID in a population of horses aged ≥ 15 years. Methods: Owner-reported data were obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners was visited and veterinary examination performed on horses aged ≥ 15 year...
Beech J, Boston RC, McFarlane D, Lindborg S.To measure plasma ACTH, alpha-melanocyte-stimulating hormone (aloha-MSH), and insulin concentrations during various photoperiods between February and October in horses and ponies with and without pituitary pars intermedia dysfunction (PPID). Methods: Cohort study. Methods: 13 clinically normal (control) ponies, 14 clinically normal (control) horses, 7 ponies with PPID, and 8 horses with PPID. Methods: Blood samples were collected from February through October during 8 photoperiods: 1, February 13 through March 2; 2, April 4 through 6; 3, June 19 through 22; 4, August 6 through 7; 5, August 14 ...
McGowan CM, Frost R, Pfeiffer DU, Neiger R.Serum insulin concentration and its use as a prognostic indicator in horses with equine Cushing's syndrome (ECS) have been poorly documented. Objective: To examine daily insulin variations in horses with ECS and the effect of treatment using trilostane, a competitive inhibitor of 3beta-hydroxysteroid dehydrogenase. Further, we aimed to examine the relationship between baseline serum insulin concentration and survival in horses with ECS. Methods: Basal serum insulin concentrations were measured in 20 confirmed ECS cases by taking blood at regular 4 h intervals for 24 h (1200, 1600, 2000, 2400, ...
Morgan RA, Keen JA, McGowan CM.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 ...
Karikoski NP, Patterson-Kane JC, Singer ER, McFarlane D, McGowan CM.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 ...
Beech J, Boston R, Lindborg S, Russell GE.To compare the effect of thyrotropin-releasing hormone (TRH) administration on endogenous ACTH concentrations in healthy horses and those with pituitary pars inter-media hyperplasia and compare the test with the dexamethasone suppression test (DST). Methods: Prospective case series. Methods: 15 horses with clinical signs of pituitary pars intermedia dysfunction (PPID), 4 horses with equivocal signs of PPID, and 29 horses without signs of PPID. Methods: ACTH concentrations prior to and after administration of TRH were measured 61 times in 48 horses. Results of the DST (cortisol response) were c...
Donaldson MT, LaMonte BH, Morresey P, Smith G, Beech J.Medical records of 27 horses (including 13 ponies) treated with pergolide or cyproheptadine for pituitary pars intermedia dysfunction were reviewed to determine the effect of treatment on plasma ACTH, insulin, and glucose concentrations and clinical signs. Prior to treatment, the most common clinical signs were laminitis, hirsutism, and abnormal body fat distribution. The median pergolide dose was 3.0 microg/kg p.o. q24h (range, 1.7-5.5 microg/kg). All horses treated with cyproheptadine were given 0.25 mg/kg p.o. q24h. After pergolide treatment, ACTH concentrations (n = 20; median = 30.4 pg/ml...
