Texas Equine Veterinary Association

www.texasequineva.com • 17 endocrinopathic laminitis. While EMS can affect horses of any age, PPID is rather uncommon in horses less than 15 years of age. Horses can be concurrently affected by both PPID and EMS and it is recommended that clinicians test for both in patients greater than 10 years of age with signs of regional adiposity and/or laminitis. Although management of PPID and EMS can be similar, PPID treatment also includes administration of pergolide and therefore a definitive diagnosis of the disease is helpful in guiding treatment. The reader is directed to the references for guidelines of PPID testing. 4 Using human metabolic syndrome as a guide, additional clinical presentations of EMS have been investigated. Reproductive unsoundness of mares suffering from EMS has been reported. 5, 6 A few studies have found evidence of hypertensive cardiomyopathy in ponies with insulin dysregulation but additional research is needed in order to determine the clinical significance. 7,8 There is growing evidence regarding the role of the microbiome in EMS and it continues to be a focus of ongoing studies. 9 Definitive evidence supporting alterations in systemic inflammation in horses with EMS is currently lacking. DIAGNOSIS – Sometimes clinical presentation is sufficient to make a presumptive diagnosis of EMS. However, a more definitive diagnosis can be made via laboratory markers for ID and there are several testing options that can be performed in the field. Regardless of the test, the clinician must keep in mind that stress can affect insulin and glucose concentrations. Therefore, it is advised that the stresses of transport or environmental change be minimized. It is also important to note that active laminitis is a stressful condition, which may complicate the diagnosis of ID in the face of an acute episode of laminitis. Recent research has also found that excessive fasting could cause insulin resistance in horses. 10, 11 Therefore, it is no longer recommended for horses to be fasted for extended periods prior to testing. More specific recommendations are listed below. 1,3 Resting/basal insulin is a simple option for testing and hyperinsulinemia may be suggestive of ID. This test is best for identifying more severely affected animals. • Collect blood after hay feeding. Grain should not be fed within four hours of testing. o Ideally, the hay feeding consists of a low nonstructural carbohydrate (NSC) forage as most reference values are based on horses receiving a low NSC hay such as coastal hay. Check with the laboratory for reference values and type of blood sample (i.e. EDTA or serum) Dynamic testing may be necessary for better assessment if results of basal insulin test are normal or equivocal. Figure 1 – A oroughbred mare who was diagnosed with EMS and PPID. e mare has evidence of regional adiposity along her dorsal neck (arrow) usually referred to as a "cresty neck". She also has an abnormal stance in her forelimbs suggestive of foot pain. (Photo credit of Piper Norton)

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