Guy Lester

Background
Sand enteropathy is a common disease in horses worldwide. The presence of sand does not always cause disease. The amount of sand required to cause clinical disease is not well established.

Objectives
To establish a weight-indexed cut-off for the diagnosis of clinically relevant sand enteropathy based on radiographic area.

Study design
Cross-sectional.

Methods
Abdominal radiographs were acquired from clinically normal horses and compared with horses with clinical sand enteropathy. Sand area and sand area per kilogram of body weight were calculated. A receiver operating characteristic (ROC) curve was used to differentiate groups.

Results
Seventy clinically normal horses and 57 sand enteropathy cases were included. Median sand area in control horses was 1 cm2 per 100 kg (interquartile range 0–6 cm2 per 100 kg), and in sand enteropathy horses was 118 cm2 per 100 kg (interquartile range 83–180 cm2 per 100 kg). Receiver operator characteristic (ROC) analysis revealed that using a cut-off of 21 cm2 per 100 kg had a sensitivity of 98.25% (CI 90.71%–99.1%) and a specificity of 92.54% (CI 83.69%–96.77%) for a diagnosis of clinical sand enteropathy.

Conclusions
A weight-based cut-off of >21 cm2 per 100 kg for the diagnosis of sand enteropathy was determined with excellent sensitivity and good specificity. This may aid in determining if the amount of sand accumulation in a horse is of clinical consequence.

Introduction: Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are prescribed to manage hyperinsulinemia but the effects of dapagliflozin have not been investigated. Although hyperlipaemia is very rare, hypertriglyceridemia is commonly associated with SGLT2i treatment and investigation of the lipoprotein profiles is warranted.

Methods: Retrospective analysis of clinical records and stored serum from horses with hyperinsulinemia that received dapagliflozin (0.02 mg/kg, [n = 34]) or ertugliflozin (0.05 mg/kg [n = 24]) PO SID for 30 days. Within-horse changes, correlations between variables, and differences between treatments were assessed using Wilcoxon signed-rank, Spearman's rank correlation coefficient (rho) and the medians tests, respectively.

Results: Between day 0 (pre-treatment) and day 30 within-horse changes (median, inter-quartile range [IQR]) were: basal serum [Insulin] (uU/mL) reduced from 170 (92-280) to 28.7 (14.5-90) (P < .0001), lameness grade (scale 0-12) reduced from 6 (4-10) to 2 (0-2) (P < .001), serum [triglyceride] (mmol/L) increased from 0.5 (0.3-0.6) to 1.0 (0.6-1.56), [β-hydroxybutyrate] (μmol/L) increased from 0.22 (0.17-2.7) to 0.30 (0.24-0.35) (P < .0001), [total cholesterol] (mmol/l) increased from 2.36 (2-2.6) to 2.84 (2.4-3.7) (P < .0001) and, as a percentage of serum lipids, high-density lipoprotein (HDL) reduced from 52.4% (47.9%-61.0%) to 50% (41%-54.8%) (P = .034), very-low density lipoprotein (VLDL) increased from 10.4% (6.4%-14.4%) to 12.3% (9.9%-16.8%) (P = .005). Differences between ertugliflozin and dapagliflozin groups in these parameters were not significant at day 0 or 30. At day 30, 10/48 (21%) cases had [triglycerides] >2.0 mmol/L (maximum = 10.8 mmol/L). Day 30 [triglyceride] was correlated with day 0: basal insulin (P < .001, rho = 0.47), [triglyceride] (P = .003, rho = 0.42) and %VLDL (P = .019, rho = 0.34) and day 30: [total cholesterol] (P < .001, rho = 0.67), %HDL (rho = −0.432, P = .014) and %VLDL (rho = 0.708, P < .001).

Discussion and clinical relevance: Dapagliflozin or ertugliflozin treatment is associated with reductions in [insulin] and lameness grade. Changes in [triglyceride] and lipoprotein profiles were usually minor with occasional marked hypertriglyceridemia. [β-hydroxybutyrate] increased indicating ketosis, a metabolic pathway previously not thought to be relevant in horses.

ORAL PRESENTATION ACVIM Resident Research Abstract Award Winner

The metabolic and lipid profiles of horses treated with sodium-glucose cotransporter 2 inhibitors are not well understood. This retrospective study evaluated blood parameters in hyperinsulinemic horses treated with either ertugliflozin (0.05 mg/kg) or dapagliflozin (0.02 mg/kg) orally once daily. Blood samples were collected at baseline (day 0) and after 7 and/or 30 days of treatment. Statistical analyses were conducted using Wilcoxon signed-rank, Mann-Whitney and Spearman's rank correlation tests. Thirty-four horses received dapagliflozin and 24 received ertugliflozin. Significant (p<0.05) within-horse changes between day 0 and day 30 included [median, inter-quartile range (IQR)]: basal serum [Insulin] (uU/ml) reduced 170 (92-280) to 28.7 (14.5-90); [triglycerides] (mmol/l) increased 0.5 (0.3-0.6) to 1.0 (0.6-1.56), [β-hydroxybutyrate] (umol/l) increased 0.22 (0.17-2.7) to 0.30 (0.24-0.35); [total cholesterol] (mmol/l) increased 2.36 (2-2.6) to 2.84 (2.4-3.7); and GGT (IU/ml) increased 21 (16-32) to 25 (18-38). As a percentage of total serum lipids, high-density lipoprotein (HDL) reduced 52.4 % (47.9 %-61.0 %) to 50 % (41 %-54.8 %) and very-low density lipoprotein (VLDL) increased 10.4 % (6.4 %-14.4 %) to 12.3 % (9.9 %-16.8 %) (all p<0.05). Differences between ertugliflozin and dapagliflozin groups were not significant in any of these parameters at days 0, 7 or 30. At day 30, 10/48 (21 %) cases had [triglycerides] > 2.0 mmol/l (maximum = 10.8mmol/l). Day 30 [triglyceride] correlated with day 0: basal insulin (rho=0.47); [triglyceride] (rho=0.42); %VLDL (rho=0.34) day 30: [total cholesterol] (rho=0.67), %HDL (rho=-0.432) and %VLDL (rho=0.708). Our findings suggest that SGLT2 inhibitors induce minor changes in lipid profiles, with occasional cases of marked hypertriglyceridemia, and that dapagliflozin and ertugliflozin exhibit similar biochemical effects.

Background
Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are being used increasingly in equine practice. While there is emerging clinical evidence of the safety and efficacy of these drugs, there are currently no reports to document owner experiences with treatment.

Objective
The objective of the study was to report owner experiences and observations following treatment with SGLT2i in horses.

Study design
A cross-sectional online survey.

Methods
Horse owners were recruited via social media, online forums and their veterinarians to participate in an anonymous online survey to document their experiences and observations when treating their horses with SGLT2i.

Results
Three hundred forty-two responses met the inclusion criteria. Ertugliflozin was the most commonly prescribed SGLT2i (79.8%), and the most common reasons for treatment were high insulin concentrations (84.2%) and active laminitis (59.7%). 85.3% of owners reported their horses had an improved quality of life after commencing treatment, while 9.4% reported no change and 5.3% reported a worsening of clinical signs. Of owners who had considered euthanasia prior to treatment (n = 77), 80.5% reported their horse's level of pain to be either mild or absent after 30 days of treatment and 94.8% reported their horse's quality of life to be improved. Most owners (n = 220, 64.7%) reported they were either extremely satisfied or somewhat satisfied (n = 72, 21.2%) with treatment. Treatment concerns included safety/side effects, medication cost, availability and long-term efficacy. 114 owners (33.3%) reported one or more initial adverse effects upon induction onto the medication, particularly excessive urination (n = 70, 20.5%), excessive drinking (n = 38, 11.1%), excessive weight loss (n = 34, 9.9%) and dullness (n = 26, 7.6%).

Main limitation
Sampling bias through social media and veterinary practices and reliance on subjective owner reports.

Conclusion
The use of SGLT2i in horses was associated with excellent rates of owner satisfaction and owner-reported improved quality of life for the horse; however, some adverse effects were observed.

Background
Preliminary evidence indicates that ertugliflozin benefits horses and ponies (hereafter collectively referred to as horses) with hyperinsulinaemia and hyperinsulinaemia-associated laminitis. The effects of ertugliflozin on the results of the oral sugar test used widely in the assessment of insulin dysregulation (ID), have not been reported.

Objectives
To report the effects of ertugliflozin on responses to the oral sugar test (OST) in horses with ID.

Study design
Retrospective case series.

Methods
Clinical records were reviewed to identify horses with ID that had an OST (0.45 mL/kg Karo-Light PO) performed before and after 4 days of treatment with 0.05 mg/kg ertugliflozin PO s.i.d. Pre- and post-treatment insulin concentrations were compared using Wilcoxon sign-ranked tests.

Results
Ten horses with ID met the inclusion criteria. Significant reductions in plasma insulin concentration were identified at all time points after 4 days of treatment with ertugliflozin relative to pre-treatment values. At T0 (prior to oral sugar), median insulin concentration reduced from 22.4 μu/mL (IQR: 6.5, 39) pre-treatment to 4.8 μu/mL (IQR: 3.7, 9.2) at day 4 (p = 0.004). At T60 (60 min after oral sugar), median insulin concentration was 165 μu/mL (IQR: 61.2, 222) pre-treatment and 78.1 μu/mL (IQR: 30.5, 137) at day 4 (p = 0.004). At T90 (90 min after oral sugar), median insulin concentration was 170 μu/mL (IQR: 88.6, 269) pre-treatment and 84.7 μu/mL (IQR: 28.7, 122) at day 4 (p = 0.002). Serum triglyceride concentration increased from a median of 0.4 mmol/L (IQR: 0.2, 0.8) pre-treatment to 0.9 mmol/L (IQR: 0.6, 2) at day 4 of ertugliflozin treatment (p = 0.006).

Main limitations
A small heterogenous group of horses and ponies, some with PPID, were used in the absence of a control group.

Conclusions
Four daily doses of ertugliflozin at 0.05 mg/kg was associated with lowering of insulin concentrations at baseline and in response to an OST in horses with ID; however, insulin levels did not return to normal in all horses. Increases in triglyceride concentrations were also observed.

Objective To investigate the relationship between bronchoalveolar lavage fluid cytology, particularly mast cells, and airway hyper‐reactivity in athletic horses presented for poor performance that included a respiratory tract evaluation in two disparate locations in Australia. Design Multi‐centre, retrospective and prospective cross‐sectional study Methods Eighty four adult horses underwent both pulmonary function testing and histamine bronchoprovocation with a commercial flowmetric plethysmography system. A bronchoalveolar lavage was performed four to twelve hours later. Bronchoalveolar lavage fluid cytology was categorised using two differing classification systems to define mild equine asthma. Statistical analysis was used to assess associations between bronchoalveolar lavage fluid relative inflammatory cell percentages, and airway hyper‐reactivity and their associated categorisations. Results Sixty four percent (54/84) of horses displayed airway hyper‐reactivity, as defined by PC35 < 6 mg/ml of histamine. A relative mastocytosis was the most common bronchoalveolar lavage fluid cytological abnormality. Horses with a sole mast cell response of ≥ 5% within their bronchoalveolar lavage fluid displayed airway hyper‐reactivity at a lower dose of nebulized histamine than horses with normal bronchoalveolar lavage fluid cytology. Horses with mixed cell responses (relative mast cell percentage > 2% and/or relative neutrophil percentage > 5% and/or eosinophil relative cell percentage ≥ 1%) displayed airway hyper‐reactivity at a lower dose of nebulized histamine than horses with normal bronchoalveolar lavage fluid cytology. Conclusion In the Australian context, recently revised increased bronchoalveolar lavage fluid cytology relative cell percentage cut offs appear appropriate for sole mast cell responses. The historical lower cut offs appear to be appropriate for mixed inflammatory cell responses

Objective To determine the agreement of invasive blood pressure measured in the facial artery, the metatarsal artery and the carotid. Additionally, to evaluate the effects of two haemodynamic conditions on agreement. Study design Prospective, randomized study. Animals Eight horses aged 7 (4 -23) years with a body weight of 493 ± 33 kg. Methods Horses were anaesthetized and positioned in dorsal recumbency. Invasive blood pressure was measured simultaneously via catheters placed in the facial, metatarsal and carotid artery. Cardiovascular function and agreement between arteries was assessed before and during administration of phenylephrine and sodium nitroprusside. These were administered until carotid mean pressure (MAPc) increased or decreased from baseline (65 ± 5 mmHg) to > 90 mmHg or < 50 mmHg, respectively. Data recorded at each sample time included systolic (SAP), mean (MAP) and diastolic (DAP) for carotid (c), facial (f) and metatarsal (m) artery as well as cardiac output (Q̇t) and systemic vascular resistance (SVR). Bland-Altman analysis was used to assess agreement between peripheral and central sites and regression analysis was used to determine influence of Q̇t and SVR. Results The largest difference was observed in SAPc and SAPm with a bias and limits of agreement (LOA) of 2 (-15 to 19) mmHg. The bias (LOA) for MAPc and MAPf was 2 (-4 to 9) mmHg and for MAPc and MAPm was 5 (-4 to 14) mmHg. The best agreement for DAP was seen between DAPc and DAPf with bias (LOA) of 1 (-3 to 5) mmHg. Regression analysis indicated marginal influence on agreement by Q̇t on MAPc and MAPf. Conclusion and clinical relevance The MAP and DAP of the carotid was generally higher compared to the peripheral arteries, which may lead to overzealous treatment of hypotension, albeit maintaining central pressures. Cardiac output and systemic vascular resistance did not largely influence the difference between sites.

Objective To characterise the relationship between bronchoalveolar lavage fluid (BALF) cytology and pulmonary function testing with histamine bronchoprovocation (HBP) methods in a population of clinically normal horses. Design Cross‐sectional study Methods Clinically normal adult horses (n = 33) underwent pulmonary function testing and HBP with a commercial flowmetric plethysmography system. BAL was performed 1–5 days later. Statistical analysis was used to assess associations between BALF cell concentration, relative inflammatory cell percentages and categorisation, and airway hyper‐reactivity (AHR). Results AHR (PC35 ≤ 8 mg/mL) was demonstrated in 17 (52%) of the horses. Using current definitions, BALF cytology was consistent with inflammatory airway disease in 14 (42%) of the horses and 7 of those demonstrated either mastocytic and/or eosinophilic responses. There was no correlation between total inflammatory cell counts or relative percentage and AHR. No statistical association was found between BALF inflammatory cell categories and AHR. Conclusion A direct association between cytological evidence of airway inflammation and AHR was not identified in this population of clinically normal horses. Determining the presence and measuring inflammatory cell mediators in BALF may more accurately reflect AHR. In addition, normal values for cell proportions in BALF may vary between different populations of horses and more appropriate regional reference ranges should be established.

Background Exercise‐induced pulmonary haemorrhage (EIPH) is considered a progressive disease based on histopathology, but it is unknown if tracheobronchoscopic EIPH severity worsens over time. Objectives The aim of this study was to examine tracheobronchoscopic EIPH changes over time in a population of Thoroughbred racehorses. A secondary aim was to identify factors that affect changes in tracheobronchoscopic EIPH severity between observations. Study design Prospective, longitudinal, observational cross‐sectional study. Methods Thoroughbred racehorses were examined with tracheobronchoscopy no earlier than 30 min after racing. Examinations were recorded and graded blindly by experienced veterinarians using a 0–4 scale. Horses with 2 or more observations were included in the analysis. The association between the previous and current EIPH score was investigated using a linear mixed effect model. Factors associated with transitioning from a lower to a high EIPH grade and vice versa were examined using multiple ordinal regression. A semi‐parametric regression model was used to examine progression using the number of career starts as a marker for time. Models were adjusted for potential confounding variables. Results There were 2974 tracheobronchoscopic examinations performed on 747 horses. Blood was detected in over half of all examinations (55.6%). The population prevalence of EIPH increased as the number of examinations for each horse increased. The preceding EIPH score was significantly associated with the current EIPH score. Significant variables associated with moving between EIPH grades were the number of days since last racing, ambient temperature and weight carried. Tracheobronchoscopic EIPH is mildly progressive over the first thirty career starts. Main limitations Enrolment was voluntary. Horses were not followed for their entire career. Conclusion Limiting the number of days in the current racing preparation and spacing races for horses with moderate to severe EIPH may be beneficial for reducing tracheobronchoscopic EIPH severity. The association between ambient temperature and EIPH warrants further investigation.

Case report: A 7-year-old Clydesdale gelding was referred with a history of progressive lethargy and ventral oedema. The horse developed diarrhoea after treatment with antibiotics by the referring veterinarian. History, clinical signs, imaging and laboratory findings were consistent with hypertrophic cardiomyopathy complicated by antibiotic-associated colitis. Progression of clinical signs prompted euthanasia and the antemortem diagnosis of hypertrophic cardiomyopathy was confirmed at postmortem examination. Conclusion: Primary HCM is reported as rare in horses, but specific descriptions are lacking. The history, clinical, laboratory and postmortem findings in this case supported a diagnosis of HCM, complicated by antibiotic-associated colitis.