Clinical Nutrition

This part of my blog focuses on feeding strategies for the management and prevention of some nutrient-related diseases and disorders in horses and ponies. This part of the blog is designed to ensure you have a good understanding of the nutritional management of horses and ponies affected with laminitis and obesity, and also dietary management of older horses. By the end of this blog post you should be able to discuss rations for horses with specific nutrition-related disorders.

* Nutritional management of:
  - Horses/ponies susceptible to laminitis
  - Obesity
  - Horses/ponies with weight loss
  - Older horses/ponies

LAMINITIS
* "Barley Disease"- starch overload
* Pasture associated laminitis
  - High WSC
* Survey taken in the 1990's of cases of laminitis in UK
  - 61% at grass
  - 30% combined
  - 9% stabled
* US Survey: 46% of cases linked with pasture

LAMINITIS- PASTURE ASSOCIATED
* Turning out horses/ponies onto:
  - Lush pasture (actively photosynthetic)
  - Stressed pasture (low environmental conditions for growth)
  - Especially spring/summer
* Seems to trigger laminitis
  - When they ingest high WSC
* Recurrent in certain individuals
* Trigger= WSC containing pastures
* Spring/summer
* WSC levels= higher variable
* Varies throughout the day
* Grass species= higher variable
  - Ryegrass> fescue> timothy> grass
* Plant part is important
  - Stems and leaves
* High WSC pastures may influence laminitis in other ways
  - May promote insulin resistance
  - Insulin peaks similar to high starch diets
  - Lower threshold for laminitis to be triggered
* Other threshold lowering factors may be involved
  - Obesity
  - Genetic predisposition

OBESITY AND INSULIN RESISTANCE
* Man
  - Regional adiposity (visceral) is linked to diabetes and heart disease
* Horses/ponies
  - Regional adiposity (crest) is linked with laminitis
* Laminitis also linked to:
  - Generalized obesity
  - Hyperinsulinemia
  - Hyperleptinemia

OBESITY IN HORSES
* No universally accepted definition of obesity in horses/ponies
  - Henneke PCS= 8 to 9
  - 7= overweight
* BCS doesn't account for regional adiposity
  - May signify higher risk of disease
* But:
  - Not all horses/ponies that are obese develop laminitis
  - Not all obese horses are IR
  - Some "acceptable conditioned" animals are IR
  - Other possible risk factors may exist

LAMINITIS- AVOIDANCE
* Consider zero grazing
  - Use suitable forage alternative
* Turnout when fructan/WSC likely at lowest
  - Late at night to early morning
  - Remove from pasture by mid-morning
* Do not graze pastures not well managed
  - Maintain young leafy swards not mature stemmy pastures
* Avoid/restrict turnout in spring and autumn
* No turnout on pastures exposed to low temperatures
  - e.g. frosts followed by warm, bright sunny days
* Do not graze pastures during/following drought
* Grazing muzzles
  - Ensure water intakes
  - Behavioral issues
* Strip grazing
* Mowing and removal of cut grass
* Turnout in an arena (provide alternate forage)
* Rotate paddocks
  - Other species (cattle/sheep) so the grass stays the appropriate height
* Forage- base the diet on forage
* For horses with history of laminitis:
  - Analyse forage- feed forage with less than 10% WSC
  - Many hays in UK higher in WSC
  - Soak in water for atleast 3 hours to help lower WSC content
  - Soaking variable- best to feed lower WSC forage
* Broad spectrum vitamin/mineral supplement
* No evidence to suggest magnesium to lower laminitis
* Supplementary feeding most won't need this
* Avoid feeds that exacerbate IR
  - Cereal grains and NSC pasture
* Use oil instead of cereal grains (unless contraindications)
  - Introduce oil gradually into the diet
  - Add vitamin E at 100-150 iu/100 ml oil
  - No more than 100 ml oil/100 kg BW
* If cereal grains are fed
  - Need to processed by cooking (e.g. micronisation)
  - Increases SI starch digestibility
  - Restrict meal sizes to 0.25kg/100 kg BW of cereal based feed
Ensure overall starch intake is less than 1 g starch/kg body weight
* Other considerations
  - No sudden dietary changes
  - Avoid abruptly starving animals
  - Regular exercise wherever possible
  - Avoid development of obesity
  - Aim= BCS between 4 & 5 (moderate) out of 9
  - If overweight- plan a weight management program

OBESITY- WEIGHT MANAGEMENT
* Eat less and Exercise more
* General principals:
  - Total removal of high calorie feeds (cereal grains and oils)
  - No excessive feeding of treats (carrots, apples, etc)
  - Assess workload- be realistic about workload
  - Set realistic goals
  - Gradual dietary changes- avoid prolonged periods of fasting
  - At target weight- develop a weight maintenance program
  - Long term commitment is 4 to 6 months

WEIGHT MANAGEMENT- HORSE STABLED
* Removal from pasture- ONLY WAY TO CONTROL INTAKE
* Studies shown no change in BW with restricted access to pasture
  - 12 hours restricted access
  - High grass consumption during grazing period
  - Estimated ponies can eat 40% of daily DMI in 3 hours at pasture
* Advisable to begin at 2% BW/day for 6-8 weeks
* If weight loss by feed restriction alone lower the feed provision
* Lower to 1.5% of current BW per day for 8 weeks
  - Divide ration into 3-4 feeds per day
  - Use haynets with small holes

WEIGHT MANAGEMENT- HORSE KEPT AT GRASS
* Restrict access to small well managed paddocks
* Ensure free from toxic plants (hungry animals may eat them)
* Stall for significant portions of the day (feeding forage)
* Strip grazing
* Use grazing muzzle
* Muzzles
  - Not always easy to use
  - Duration of muzzling needs changed as BW changes
  - Horse/pony needs some time without muzzle
** NOTE: Short term removal from grazing by stabling or muzzling is healthier for the horse, although many people think that stalling is not good for their health or well-being.

WEIGHT MANAGEMENT- EXERCISE
* Weight loss increases when diet decreases and exercise increases
* 10 minutes walking in hand twice daily for first week
* Gradually increased to 1 hour daily
* As exercise increases feed restriction can be lowered

WEIGHT MANAGEMENT- MONITORING
* Not all animals lose weight at the same rate
* BCS not useful for short-term monitoring (less than 3 months)
* Horses should be checked weekly
* Using weighbridge or weight tape

HORSES/PONIES WITH WEIGHT LOSS
* Reasons:
  - Disease (needs investigation)
  - Poor nutrition (neglect or ignorance)- inadequate energy provision
  - Horses that are mis-managed are likely to eat food when offered
  - Diseased horses will not eat when offered food
* Some diseased horses eat and still lose weight
  - Poor absorption
  - Excessive loss or metabolism of nutrients
* A number of contributing factors may be present
  - e.g. marginal diet and poor dentition
* Considerations:
  - Teeth
  - Anthelmintic program
  - Evaluate the diet
* Absence of disease
  - Higher intake of digestible nutrients
  - Diet depends on extent of weight loss and age (growing)
* Severe cases (less than 3.5 of Henneke BCS Scale)
  - Gradual changes essential (re-feeding syndrome)
  - Usually occurs 3 to 5 days post change in diet
  - Electrolyte imbalances associated with high NSC feeding
* Re-feeding:
  - High fat, low NSC
  - Lucerne- High protein, low NSC
  - Grass hay- soak for atleast 3 hours
  - Small (0.5 kg) frequent meals (6 times daily) of forage
  - Gradual increase in amount over 10 days
  - Then gradually add higher energy dense feed
  - Maintain weight mid-point BW current and desired BW
  - Then increase feed gradually to reach desired weight
  - Oil is good- needs to be added gradually
  - Check electrolyte intake

OLDER HORSES
* Some studies shown lower digestibility
  - CP, phosphorus and fiber digestibility
* Others shown no difference
* Attributed to:
  - Damage to large colon (chronic parasitism)
  - Poor dentition
* Thus can assume older, healthy horses can be fed as per normal adult horse guidelines

OLDER HORSES- PROBLEMS
* Weight loss is most common nutritional problem
* Can be several causes:
  - Dental abnormalities
  - Renal and hepatic disease
  - Cushing's Disease
* Incidence or periodontal disease
  - One study: 60% in horses over 15 years of age
  - Second study: similar incidence in horses over 20 years of age
* Dietary Management
  - Grass is easier to chew than long-stem hay
  - Turnout is desirable
  - Feed high quality forage (high leaf to stem ratio)
  - Chop if required
* Severe cases
  - Commercial senior feed
  - Mixed with high fiber cube (alfalfa pellets or cubes)
  - Soak before feeding (warm water= higher palatability)
  - High volume of feed will lower daily DM intake
  - Oil can be added (if not in commercial feed)
  - Add Vitamin E if oil used (100 IU/100 ml oil)
  - Small, frequent feedings

OLDER HORSES- OTHER CONSIDERATIONS
* Often high quality and/or quantity of feed can increase intake and BCS
* Some horses increase intake if fed with companion horses
* Soak feed in warm water
* Add molasses or pureed apple
* Add flavorings i.e. crushed ginger cookies
* Older horses usually lower pecking order in field
  - Feed separately to increase intake
* Older horses may have OA
  - Feed from raised container to increase intake- OA of forelimbs
  - Raised container for hay (no haynet)- OA of neck

CLINICAL NUTRITION CONCLUSION
* Diet can impact on development of disease
* Good dietary management can prevent disease
* Dietary management can improve health
* Diet is integral to health
* PREVENTION IS BETTER THAN A CURE!!!!!!!!!!!!!!!

Abbreviations used in this section:
 

ADF = acid detergent fibre

BCS = body condition score

BW = bodyweight

Ca = calcium

CH4= methane

CHO = carbohydrate

CF = crude fibre

CO2= carbon dioxide

CP = crude protein

DE = digestible energy

DM = dry matter

DP = degree of polymerisation

G = grams

GIT = gastrointestinal tract

H2O = water

HT = High temperature

LAB = lactic acid bacteria

LI = large intestine

LW = live weight

IR = insulin resistance

Mg = milligrams

MJ = megajoules

NSC = non-structural carbohydrates 

 

VIDEOS TO WATCH REGARDING LAMINITIS