Nutritional considerations for the management of equine pituitarypars intermediadysfunction

Abstract

Summary Pituitary pars intermedia dysfunction (PPID) is a common endocrine disorder affecting equids. To help achieve and maintain healthy body condition, whilst reducing the risk of dietary associated laminitis, appropriate nutritional management is key. This review proposes a stepwise approach to building an individual nutritional plan for equines with PPID. Starting with considerations relating to current and desired body condition and muscle mass, it highlights the importance of providing appropriate amounts and forms of energy, carbohydrate and protein, with further practical considerations regarding the feeding of animals that are often aged and may have particular clinical sequelae to PPID. The next important step is to determine the degree of insulin dysregulation (ID), as this is a major factor associated with an increased risk of laminitis. Animals with ID should be fed low non‐structural carbohydrate (NSC) providing feeds/feedstuffs as well as fresh or preserved forage with NSC content <10‐12% on a DM basis. Finally, adjustments need to be made according to life stage and activity level.

Pituitary Pars Intermedia Dysfunction (PPID) in Horses

“…It is not known if, or how, PPID affects insulin concentrations [ 64 , 65 ]. Many studies have come to contradictory conclusions [ 62 , 66 , 67 ], but results of recent studies suggest that ID is an indicator of PPID chronicity, PPID and ID are different conditions or PPID exacerbates existing ID through undetermined processes [ 65 , 68 , 69 , 70 , 71 ]. More research is required to establish whether the conditions are different or interrelated.…”

“…A potential link has been established between PPID and hyperinsulinaemia that can lead to laminitis [ 62 , 65 , 158 ]. While ACTH concentrations are not predictive of laminitis risk [ 159 ] and hyperinsulinaemia and PPID may not necessarily be linked [ 62 ], if horses with PPID have a history of laminitis or have been diagnosed with insulin dysregulation, feeds high in non-structural carbohydrates should be avoided [ 71 , 159 ]. However, because horses with PPID often experience weight loss and muscle wastage, close attention should be paid to the horse’s body condition score.…”

“…If horses begin to lose weight, supplementary feeding should be implemented to improve body condition and the diet should be tailored based on insulin dysregulation status. All diets should be tailored to age, body condition and athletic use [ 71 ]. A strong negative association between serum vitamin B12 and PPID was observed when investigating the relationships of inflamm-ageing with nutrient levels and PPID in a population of 42 senior horses [ 160 ].…”

“…Vitamin B12 deficiency has been associated with Parkinson’s disease [ 161 ], Alzheimer’s disease [ 162 ] and human patients with Cushing’s disease [ 163 ], and is essential for normal central nervous system function [ 164 , 165 ]. There may be a correlation between low vitamin B12 and PPID in aged horses, and supplementation of vitamin B12 may be warranted [ 71 ]; however, this requires further research.…”

“…Immune function is altered in horses with PPID and subsequently strict preventive healthcare measures and biosecurity protocols should be put into place [ 63 ]. Regular dental examinations and faecal egg counts should be performed, due to an increased risk of age-related dental disease [ 71 ] and the increased risk of secondary infections [ 7 , 63 ] and endoparasitism [ 96 ]. Horses with dental disease that cannot tolerate consumption of long fibre length dry matter should be offered chaff or fibre pellets (beet pulp) to meet dry matter intake requirements [ 166 ].…”