Glucose homeostasis and the enteroinsular axis in the horse a possible role in equine metabolic syndrome

One of the principal components of equine metabolic syndrome (EMS) is hyperinsulinaemia combined with insulin resistance. It has long been known that hyperinsulinaemia occurs after the development of insulin resistance. But it is also known that hyperinsulinaemia itself can induce insulin resistance and obesity and might play a key role in the development of metabolic syndrome. This review focuses on the physiology of glucose and insulin metabolism and the pathophysiological mechanisms in glucose homeostasis in the horse (compared with what is already known in humans) in order to gain insight into the pathophysiological principles underlying EMS. The review summarizes new insights on the oral uptake of glucose by the gut and the enteroinsular axis, the role of diet in incretin hormone and postprandial insulin responses, the handling of glucose by the liver, muscle and fat tissue, and the production and secretion of insulin by the pancreas under healthy and disrupted glucose homeostatic conditions in horses

Dermatographism in a horse, responsive to cetirizine treatment

Dermatographism is a common condition in man that occurs when pressure is applied to the skin and mast cells are triggered to release histamine, causing local urticarial lesions. This case report concerns a 4‐year‐old Quarter Horse gelding that was presented with pressure induced urticaria. Moderate pressure on the skin induced nonpruritic urticaria‐like swelling after approximately 3–5 min, which lasted for approximately 2–3 h. Initial treatment with cyproheptadine gave an incomplete response and unacceptable sedation as a side effect. On the second generation antihistamine cetirizine (0.2 mg/kg bwt twice daily), dermatographism was no longer present and no side effects occurred. Treatment was continued for 4 months, with at least three attempts to discontinue therapy resulting in recurrence of lesions within 24 h. Lesions resolved each time within 24 h of recommencing therapy. Dermatographism did not recur after the horse was moved to another location despite discontinuation of therapy. This report describes a case of equine dermatographism responsive to cetirizine

Ultrasonographic measurements of localized fat accumulation in Shetland pony mares fed a normal v. a high energy diet for 2 years

Health risks associated with obesity are more likely a factor of the localization of fat excess, rather than of elevated BW per se. The aim of this randomized controlled clinical trial was to determine the effect of a long-term high energy diet on BW, fat accumulation and localization. Eight Shetland pony mares, 3 to 7 years old, were randomly divided into a control and a high energy (HE) diet group fed either maintenance or double maintenance energy requirements (200% net energy (NE)) for two consecutive summers, with a low energy diet in the winter in between. Body condition score (BCS) did not differ between the groups at the onset of the study (control 5.6±0.75 v. HE 6.3±0.5). From 12 weeks after starting the diet, ultrasonography of five different locations (retroperitoneal, axillary, withers, intercostal and rump) for adipose deposition, BCS and BW were measured monthly during the period that ponies received different diets. Statistical analysis was performed using a linear mixed-effects model with post hoc Bonferroni testing. P values <0.05 were considered significant. At week 12 after the onset of the diet, fat thickness in the HE group was significantly greater than in the control group. During the monitoring period, the HE group showed a significant increase in mean (±SE) BW (+52%, 265±13.94kg) and BCS (+70%; to 9.0±0.4), while the control group was unchanged (BW 160±13.98 kg; BCS 3.8±0.4). At all locations, the fat depth in the HE group increased significantly, with the highest increase noted for retroperitoneal deposits. The conclusions were that a 200% NE diet induced subcutaneous and retroperitoneal fat accumulation, with the greatest increase in intra-abdominal deposits. The moderate increase of the subcutaneous fat depth followed by a plateau phase suggests the existence of a limit of adipose tissue expandability, as in man

Temporal trends in prevalence of bacteria isolated from foals with sepsis: 1979-2010

Summary: Reasons for performing study: Sepsis is an important cause of death in foals. Knowledge of which pathogens are likely to be involved is important for selection of antimicrobial drugs for initial treatment. Objectives: To identify temporal trends in prevalence of bacteria isolated from foals with sepsis between 1979 and 2010. Study design: Retrospective review of medical records. Methods: All foals ≤30 days of age presented to the Veterinary Medical Teaching Hospital (VMTH) at the University of California, Davis between 1979 and 2010, with a diagnosis of sepsis confirmed by culture of bacteria from blood or internal organs (antemortem or at necropsy), were included in the study. Conventional microbiological methods were used to identify isolated organisms. The Cochran-Armitage trend test was used for statistical analysis. Results: The percentage of Gram-positive isolates increased significantly over the years. The percentage Enterobacteriacea, and Klebsiella spp. in particular, decreased over time. Enterococcus spp. isolates were cultured more often in recent years. Conclusions: Whereas Gram-negative bacteria, particularly Enterobacteriaceae, remain the most common isolates from neonatal foals with sepsis, the prevalence of Gram-positive bacteria is increasing. This trend underlines the importance of including antimicrobial drugs active against both Gram-positive and Gram-negative bacteria in treatment protocols while awaiting the results of bacteriological culture and susceptibility tests. The increased prevalence of Enterococcus spp. is of concern because antimicrobial susceptibility patterns for enterococci are unpredictable and enterococci can also act as donors of antimicrobial resistance genes to other bacteria

The use of electromyography interference pattern analysis to determine muscle force of the deep digital flexor muscle in healthy and laminitic horses

BACKGROUND: In equine laminitis, the deep digital flexor muscle (DDFM) appears to have increased muscle force, but evidence-based confirmation is lacking. OBJECTIVES: The purpose of this study was to test if the DDFM of laminitic equines has an increased muscle force detectable by needle electromyography interference pattern analysis (IPA). ANIMALS AND METHODS: The control group included six Royal Dutch Sport horses, three Shetland ponies and one Welsh pony [10 healthy, sound adults weighing 411 ± 217 kg (mean ± SD) and aged 10 ± 5 years]. The laminitic group included three Royal Dutch Sport horses, one Friesian, one Haflinger, one Icelandic horse, one Welsh pony, one miniature Appaloosa and six Shetland ponies (14 adults, weight 310 ± 178 kg, aged 13 ± 6 years) with acute/chronic laminitis. The electromyography IPA measurements included firing rate, turns/second (T), amplitude/turn (M) and M/T ratio. Statistical analysis used a general linear model with outcomes transformed to geometric means. RESULTS: The firing rate of the total laminitic group was higher than the total control group. This difference was smaller for the ponies compared to the horses; in the horses, the geometric mean difference of the laminitic group was 1.73 [geometric 95% confidence interval (CI) 1.29-2.32], and in the ponies this value was 1.09 (geometric 95% CI 0.82-1.45). CONCLUSION AND CLINICAL RELEVANCE: In human medicine, an increased firing rate is characteristic of increased muscle force. Thus, the increased firing rate of the DDFM in the context of laminitis suggests an elevated muscle force. However, this seems to be only a partial effect as in this study, the unchanged turns/second and amplitude/turn failed to prove the recruitment of larger motor units with larger amplitude motor unit potentials in laminitic equids