Development of a Web App to Convert Blood Insulin Concentrations among Various Immunoassays Used in Horses.

The measurement of the blood insulin concentration, and comparison to cut-offs, is essential in diagnosing insulin dysregulation, a common equine endocrinopathy. However, different insulin assays provide disparate results. We aimed to ease comparison between assays by compiling original and published data into a web app to convert insulin measurements from one assay to another. Data were available for ADVIA Centaur insulin chemiluminescent immunoassay (CLIA), Beckman Coulter insulin radioimmunoassay (RIA), Immulite 1000 CLIA, Immulite 2000 CLIA, Immulite 2000 XPi CLIA, Mercodia equine insulin enzyme-linked immunosorbent assay (ELISA), and Millipore porcine insulin RIA. Linear models were fitted for 13 assay pairs using non-decreasing splines, and integrated into this app. Assay comparisons including data from several studies showed a lower performance. This indicates technical variation between laboratories, which has not been described before, but is relevant when diagnostic measurements and cut-offs are provided by different laboratories. Nevertheless, the models' overall high performance (median r2 = 0.94; range 0.57-1.00) supports their use to interpret results from diagnostic insulin measurements when the reference assay is unavailable, and to compare values obtained from different assays.

Carbohydrate pellets to assess insulin dysregulation in horses.

BACKGROUND: A glycemic challenge test is used for the diagnosis of insulin dysregulation (ID) in horses and ponies. Different forms of the test exist where the administrative route and dose of glucose vary, which makes interpretation of results challenging. HYPOTHESIS/OBJECTIVES: To evaluate the palatability of, and blood glucose and insulin responses to, carbohydrate pellets fed as an oral glucose test (OGT), and to establish the diagnostic threshold for ID when using the pellets. ANIMALS: University and privately-owned horses and ponies (n = 157) comprised of 31 breeds and both sexes. METHODS: Multicenter cohort study. A custom-produced glycemic pellet was offered for free intake at 0.5 g/kg BW soluble carbohydrate and serum insulin and blood glucose concentrations measured before and after (60, 120, and 180 minutes) the pellets were offered. Pellet acceptance and intake time (those that finished within 10 minutes) were determined to assess palatability. RESULTS: The pellets were palatable to 132/157 animals, and ponies found the pellets more (P = .004) palatable than horses. The median intake time (4 [3-6] minutes) was positively correlated with acceptance grade (r = .51; P < .0001). Consumption of the pellets elicited peak blood glucose (6.6 [5.8-7.8] mmol/L) and serum insulin (40.5 [19-99.8] µIU/mL) responses at 120 minutes. At 120 minutes the optimal cut-off was 83 µIU/mL (95% CI: 70-99 µIU/mL) for the IMMULITE 2000XPi assay. CONCLUSIONS AND CLINICAL IMPORTANCE: The pellets were palatable and a suitable, novel carbohydrate source for the OGT.

Equine metabolic syndrome in UK native ponies and cobs is highly prevalent with modifiable risk factors.

BACKGROUND: The epidemiology of equine metabolic syndrome (EMS) is poorly described. OBJECTIVES: To estimate the prevalence of EMS in native UK ponies and cobs in England and Wales and identify associated risk factors. STUDY DESIGN: Cross-sectional study. METHODS: Breeders registered with UK native pony breed societies and registered riding schools and livery yards within a set radius were invited to participate. All native UK ponies and cobs aged 3-14 years and not diagnosed or being treated for conditions likely to affect insulin regulation at participating premises were eligible. Animals underwent a clinical examination and an oral glucose test while their owner or keeper completed a questionnaire by face-to-face interview. Data were analysed by multilevel uni- and multivariable modelling using insulin concentration and EMS diagnosis as outcomes. RESULTS: A total of 354 animals were examined at 64 properties (19 studs, 19 livery yards, 26 riding schools). The overall prevalence of EMS adjusted for clustering within yard was 23.3% (95%CI 17.9%-29.8%). Risk factors associated with a diagnosis of EMS included age, being female, more sedentary main activity, obesity, and shorter periods on pasture during the summer. Compared to the Welsh section A, the other Welsh, Connemara and cob breeds all had decreased odds of EMS. Clinical manifestations of hoof growth ring and supraorbital fat scores of 3/3 were more frequent in EMS ponies and animals with a history of laminitis within the last 5 years (9.7%) were 14.4 (95% CI 5.9-35.3) times more likely to be positive for EMS than those without. MAIN LIMITATIONS: Results may not be transferable to other breeds or age groups. CONCLUSIONS: Equine metabolic syndrome is highly prevalent in UK native ponies and cobs with modifiable risk factors including obesity and sedentary activities. Modifying risk factors could help reduce the risk of laminitis in susceptible animals.

Episcleral cyclosporine A implants for the management of unilateral keratoconjunctivitis sicca in an 8-year-old mare.

An 8-year-old mare was presented for investigation of a 1-month history of blepharospasm, eyelid swelling, corneal edema, and ocular discharge of the right eye (OD). Ophthalmic examination confirmed mucopurulent ocular discharge, conjunctival hyperemia, and a dry, dull appearance to the cornea OD. Schirmer tear test results confirmed an absence of tear production OD (0 mm/min) consistent with keratoconjunctivitis sicca. Treatment with topical 0.2% cyclosporine A resulted in an improvement in clinical signs. An episcleral cyclosporine A implant was placed under standing sedation 5 days after initial presentation. Re-examination 9 days post-operatively confirmed that the mare's tear production in the right eye had improved and no further clinical signs had been observed. Topical medications were gradually discontinued. Re-examinations performed up to 12 months postsurgery showed no recurrence of clinical signs and no adverse effects of the implant. To our knowledge, this is the first report of the use of a cyclosporine A implant in the management of KCS in a horse and highlights its potential as an effective, alternative therapy in the management of KCS in horses.