Intra-articular triamcinolone acetonide injection results in increases in systemic insulin and glucose concentrations in horses without insulin dysregulation.

BACKGROUND: Corticosteroids are a commonly used, inexpensive intra-articular treatment for osteoarthritis which may increase the risk for laminitis in horses due, in part, to hyperinsulinaemia. Humans with metabolic syndrome experience increases in insulin and glucose concentrations post-injection, but responses in horses are unknown. OBJECTIVES: To determine the effect of a single intra-articular (IA) dose of triamcinolone acetate (TA) on blood insulin and glucose concentrations. STUDY DESIGN: Before-after study. METHODS: Ten horses with normal insulin regulation as assessed by an oral sugar test received 18 mg of TA into one middle carpal joint. Insulin and glucose concentrations were evaluated at baseline and 4, 6, 8, 24, 48, and 72 h following IA corticosteroid injection. Differences from baseline were evaluated using a repeated measures ANOVA with Dunnett's multiple comparison testing or a Friedman test with Dunn's correction (significant at p < 0.05). RESULTS: Mean ± SD blood insulin concentration post IA TA injection was increased at 6 h (15.8 ± 3.1 µIU/mL, p = 0.01), 24 h (23 ± 5.8 µIU/mL, p ≤ 0.001), and 48 h (29 ± 13 µIU/mL, p ≤ 0.01) compared to baseline (10 ± 12.3 µIU/mL), with the peak at 48 h. Median ± 95% CI blood glucose concentration post IA TA injection was increased at 6 h (112.7 ± 20.3 mg/dL, p = 0.006), 8 h (112.9 ± 21.4 mg/dL, p = 0.004), 24 h (122.6 ± 14.6, p ≤ 0.0001), and 48 h (123.5 ± 15.4 mg/dL, p ≤ 0.0001) compared to baseline (89.2 ± 6.6 mg/dL), with the peak at 48 h. MAIN LIMITATIONS: Only horses with normal insulin regulation were evaluated. CONCLUSIONS: Blood insulin and glucose concentrations modestly increased for 48 h following IA TA.

A comparison of rectal versus fetlock temperatures in dorsally recumbent horses during general anesthesia.

OBJECTIVE: To investigate the effect of isoflurane anesthesia on thermoregulation and peripheral heat loss in dorsally recumbent horses. STUDY DESIGN: Prospective, clinical study. ANIMALS: Seven adult horses (2.6 ± 1.5 years old, 455 ± 70.2 kg). METHODS: Horses underwent elective surgical procedures in dorsal recumbency under general anesthesia (GA) maintained with isoflurane in oxygen. Rectal (TR), intranasal (TN) and fetlock surface temperatures (TF) were measured every 10 minutes for the first 80 minutes following induction of GA. Room temperature (TRO) was monitored during the study. Statistical analysis to determine differences between temperature measurement sites and techniques (TR, TN and TF), and differences over time were completed using a mixed-effects model with Tukey's multiple comparison or Dunnett's multiple comparison testing where appropriate. Significance was set at p < 0.05. RESULTS: Following induction of anesthesia, TF was significantly increased compared with baseline (0 minutes) from 40 to 80 minutes (p < 0.01). No significant differences were detected in TR and TN at any time point compared with baseline (p > 0.05). TF was significantly lower than TN (p < 0.02) at all time points and TR from times 0 to 70 minutes (p < 0.04). There were no significant differences between TR and TN at any time (p > 0.05). CONCLUSIONS: In horses undergoing isoflurane GA, TF increased, indicating peripheral heat loss likely because of vasodilation, whereas TR showed a clinically relevant decrease over time. These findings are suggestive of body heat redistribution during GA in horses in dorsal recumbency. Thermographic imaging of the peripheral limbs in combination with TR and TN monitoring allowed for recognition of peripheral heat redistribution in anesthetized horses. CLINICAL RELEVANCE: Anesthetized horses experience peripheral heat loss through their extremities as a result of vasodilation. Mitigating peripheral heat loss may improve thermoregulation and reduce hypothermic complications in anesthetized horses.

Beta defensins as biomarkers: detectable in LPS-stimulated equine peripheral blood mononuclear cells and normal, aseptic, and probable septic equine synovial fluid.

OBJECTIVES: Diagnosis of equine septic arthritis is not straightforward, and increasing time between onset, diagnosis, and treatment can have serious consequences for quality of life. Defensins are used in diagnosis of human joint infection. The presence of beta defensins (BDs) in equine synovial fluid and their utility as a biomarker of sepsis has not been investigated; therefore, our objectives were to (1) compare in vitro gene expression of lipopolysaccharide (LPS)-stimulated equine neutrophils to unstimulated neutrophils and (2) compare BD protein expression from normal, aseptically inflamed, and septic equine joints. ANIMALS: 5 horses for isolated neutrophil BD expression and 21 synovial fluid samples from 14 horses. PROCEDURES: RT-qPCR analysis was performed for BD gene expression of stimulated and unstimulated equine peripheral neutrophils. BD protein expression was evaluated from equine joints with no disease, aseptic inflammation, and septic inflammation using a commercial ELISA designed for horses and analyzed with a Kruskal-Wallis test (significant at P < .05). RESULTS: A significant increase was noted in expression of BD-3 in LPS stimulated as compared to unstimulated neutrophils. There were no significant differences in BD expression noted between joints with no disease, aseptic inflammation, and septic inflammation. Low case numbers and different types of cases in the aseptic inflammation group were main limitations. BD expression patterns in samples from stimulated equine peripheral neutrophils and synovial fluid were identified. CLINICAL RELEVANCE: BDs are detectable in equine synovial fluid and can be stimulated from peripheral neutrophils. Further examination is needed to define their role as biomarkers of joint disease.