PG . 37 foals ; those that grow faster in height / weight and are > 5kg above average at 4 weeks of age and > 14kg at 8 months . Foals that are intermittently upright in the pasterns / contracted tendons ( both signs of rapid bone growth ) have more frequent and severe lesions . Taller foals ; being 5.5kg heavier at 25 days and 17kg at 120 days , and faster weight gains from 3-5 months increase the chance of stifle and / or shoulder lesions . Wobblers are often taller and heavier with higher body weight , wither and hip height from birth to 12 months old , and faster weight gain at 1 - 2 months , 4 - 5 months and 7 – 8 months of age . Muscle growth should not be pushed forward at a time when joints are vulnerable . A lighter , leaner weanling with appropriate height ( remember height , not muscle , is an indication of bone growth , not muscle ) is the ideal .
2 . Sweet feeds high in starch / sugar / NSC are known triggers in pregnant mares , foals and weanlings . These feeds affect blood sugar , insulin , acid levels and growth hormones for up to 4 hours after feeding . Diets based on fibre and oil , balanced with a vitamin / mineral supplement help reduce the risk of DOD and oral stereotypies .
3 . Extruded and micronized feeds must be used with caution as their increased digestibility can produce more rapid and profound effects on blood glucose and insulin ( Table 1 ). Pelleting causes lower glucose and insulin changes than textured feeds .
4 . Minerals : Deficiencies , imbalances and excesses increase the incidence and severity and reduce the chance of spontaneous resolution . Inadequate mineral intake can occur if feeds are not correctly formulated or if they are fed at below recommended levels . These errors can be corrected by the incorporation of a highly fortified , low starch vitamin and mineral supplement . The surest way of determining if nutrition is a contributing factor is to perform a diet analysis of total daily intake so deficiencies or excesses can be identified and corrected .
5 . Genetics : genetics represent approximately 25 % of the risk – the environment ( biomechanical influence , body weight , exercise and nutrition ) accounts for 75 %. All are interrelated and for foals with a genetic potential for rapid growth , correct nutrition is fundamental in preventing blood sugar and insulin surges , ensuring correct and balanced mineral intakes and regulating growth rate and body condition .
Weaning is an inevitable stressful event but with the right management we can help them transition smoothly from a nursing foal to a sound , confident yearling . DOD is selflimiting in some cases and crippling for others . Complex triggers and risk factors make diagnosis , treatment options and prognosis far from straightforward . Your veterinarian is the best source of information and advice . DOD can ’ t be completely prevented , but there are measures that support joint development .
TABLE 1 . FEED LABELS : DEFINITIONS AND WORDS THAT , TO REDUCE THE RISKS FOR DOD AND OCD , FLAG CAUTION FOR PREGNANT MARES , FOALS , WEANLINGS AND YEARLINGS *
Grain-free Usually means no whole grains - but can include grain by-products ( bran , pollard , millrun , millmix , hominy meal etc ) that are all high in starch / sugar NSC
Low sugar The feed can still be high in starch - both starch AND sugar are important ( starch PLUS sugar = NSC )
Low starch The feed can still be high in sugar - both starch and sugar are important ( sugar + starch = NSC )
Cereal by-products Typically high in starch Cereal co-products Typically high in starch
Heat-processed * Extrusion and micronisation : may also not be a good choice for horses with metabolic syndrome as increasing starch digestibility can cause a profound increase in blood glucose .
TABLE 2 : WORDS , INGREDIENTS AND PROCESSING METHODS THAT FLAG CAUTION FOR PREGNANT MARES , WEANLINGS AND HORSES WITH EMS , PPID OR INSULIN DYSREGULATION
Grain-free
Hominy meal Low GI
Low sugar
Low starch
Nutrition analysis
Cool feed
No whole grains but often include grain-by products such as bran and pollard , millrun etc which are high in NSC
Ground corn meal ~ 38-45 % NSC
Glycaemic index ( GI ) is determined by measuring insulin , glucose and ACTH before and again 1 , 2 and 3 hours after feeding to be labelled ‘ low GI ’ - request evidence that the manufacturer has done this .
It is the sugar + starch that is important so if the % starch or total NSC are not also given , it is misleading and likely unsafe .
It is the sugar + starch that is important so if the % starch or total NSC are not also given , it is misleading and likely unsafe .
Needs to list sugar - which may be listed as WSC or ESC AND starch or else the total NSC < 12 % - if this is not listed then the information is incomplete and the feed likely unsafe .
Cool feeds : implies the feed will not cause spikes in glucose , unless blood glucose levels have been measured after feeding , this term is misleading - contact the manufacturer for details of research .
A strong foundation of bone and joint development aids in performance and preventing lameness during the horse ’ s career – and the incidence of obesity and insulin resistance . An understanding of the relationship between the processes of bone and joint growth and the influence of diet on metabolism and the hormones that orchestrate skeletal development enables us to optimize growth and protect future soundness .
© Dr J H Stewart April 2024 All content provided in this editorial is for general use and information only and does not constitute advice or a veterinary opinion . It is not intended as specific medical advice or opinion and should not be relied on in place of cosultation with your equine veterinarian .
2024 AQHA YEARBOOK ~ MAY / JUNE ISSUE