Study conducted by Dr Erin Roddy, DVM. 

Meet Shadow

A 25 year old, 13 hand Welsh Pony, Shadow is retired from riding. In his long riding career, Shadow was a successful show pony and then did many years of pony club and riding school lessons before finally retiring a few years ago. He was purchased by his current owners 10 years ago to be used for pony club and lower level showing, and they have also used him as a lesson and lead rein pony as he has gotten older.  Shadow has always been an easy keeper; often becoming significantly overweight.  

A History of Laminitis

Shadow has had Laminitis numerous times over the years and seemed to be particularly vulnerable when sudden rain and warm temperatures caused his pasture to become overly lush (high in sugars).  When he was purchased, the owners were aware that Shadow had a history of laminitis and they have made every effort to control the disease and prevent future outbursts. 

Shadow is on a low starch and sugar feed (Pryde’s Easi Sport), is only turned out on pasture overnight, and is exercised regularly to maintain a healthy weight.  Shadow’s feet are x-rayed yearly to monitor his angles and sole depth and he is trimmed every 4 weeks by a knowledgeable farrier.  Despite their best efforts, Shadow has still had painful bouts of laminitis with the current owner.  There have been occasions where even night-time grazing is too rich for Shadow and he has suffered an acute bout of laminitis.  On another occasion Shadow suffered an abscess in his right front foot and was non weight bearing lame for a few days before the abscess was able to be drawn out. This set off a bout of laminitis in his left foot as his system was operating at such a high level of inflammation.   

Acquired Insulin Resistance

I chose Shadow for this case study as he is a classic example of acquired insulin resistance and dysregulation. Being a Welsh Pony, Shadow is a typical signalment (species, breed, age and gender) for a metabolic disorder as the breed is historically hardy – in the past, Welsh Ponies had  to forage extensively for calories. 

Ponies, Arabians, and Warmblood horses are typically more likely to suffer from metabolic disorders as they have evolved to be able to survive off very little caloric intake.  This makes these horses easy to maintain in good condition, but also genetically predisposes them to developing metabolic conditions when they are fed modern rich feeds and hays that are high in sugar and starch. 

In the first 15 years of his life, Shadow was fed these types of rich feeds as well as hay and lush pastures high in sugar.  Owners are often unaware that hay and grass can be high in sugars as well as hard feeds.  While Shadow looked the part of a well-conditioned show pony, internally this rich diet was wreaking havoc on his metabolic system.  Shadow’s rich diet resulted in chronic high blood sugar as he wasn’t exercising enough to burn the sugar he was consuming. 

When the level of sugar increases in a horse’s blood, the body releases insulin to signal the muscle tissues to absorb the sugar. Unfortunately, in horses with a genetic predisposition, or in horses fed a diet high in sugar and/or starch, the tissues aren’t able to absorb and use all of the sugar circulating in the bloodstream, so more insulin is released as the body attempts to combat this continuous excess of sugar in the horse’s blood.  Over time, the body’s insulin receptors become dulled to insulin as there is just so much floating around.  Some of the sugar in the blood is converted to fat and stored, which leads to visible fatty deposits (lumps) and obesity, but over time there is a continuous build up of sugar and insulin in the bloodstream. 

“Ultimately, chronic high blood sugar leads to inflammatory processes, such as laminitis.” 

What is truly heartbreaking about insulin resistance and dysregulation is that once the cycle has started it can be very difficult to correct.  Once the receptors become resistant to insulin  it becomes very hard for the body to clear the sugar from the bloodstream, and years of careful horse management are required just to maintain the animal’s health. Rarely are we able to truly reverse the damage caused.

Testing for Insulin Resistance in Horses

The blood test to diagnose insulin dysregulation involves measuring the pony’s insulin level in the blood first thing in the morning before the animal is fed.  If the insulin level is greater than 50 microunits/ml the animal is classed as insulin dysregulated.  Annual testing is useful for any pony diagnosed with insulin dysregulation, to monitor whether your management plan is being successful.

For Shadow, Insulin Resistance also led to recurrent Laminitis

Shadow’s owners had been very careful to follow all the professional recommendations to manage his insulin dysregulation and chronic laminitis.  Unfortunately, he was so insulin resistant that even the smallest increases in blood sugar or stress could cause a relapse bout of laminitis. 

Diet Restriction led to Gastric Ulcers & Stiffness

Shadow’s owners changed his housing to a stable and dirt yard to prevent any exposure to grass or pasture, and began feeding him soaked hay 4 times per day.  However, this management plan was also unsuccessful as Shadow then developed gastric ulcers from not taking in enough forage.  Shadow and his owners were caught in a very difficult balancing act as they found that when they fed enough soaked hay to manage his ulcers, they were unable to keep his weight and blood insulin levels under control.  Being confined all the time also made Shadow depressed and stiff.  He became disinterested in being ridden anymore, and his owners also felt he was too stiff and uncomfortable for even gentle exercise. 

When we met Shadow’s owners, they were considering euthanizing him, as they didn’t feel his quality of life was at all acceptable. 

MetaboLize® Delivers Results

We recommended the owners start Shadow on MetaboLize® in an effort to improve his quality of life. 

The results included a dramatic improvement in Shadow’s movement and mood, and reduced fatty lumps and cresty neck:

• Within a few days, Shadow was much more mobile, and began to walk willingly around his pen.
• He began greeting his owners with a brightness and excitement they hadn’t seen in years. 
• Within days on MetaboLize®, his owners started turning Shadow out in the round pen, and he was offering to trot and canter on his own. 
• After two weeks Shadow was turned out in the arena and his owners were delighted to see that he would frolic and play.  
• His fatty lumps and cresty neck reduced in volume significantly in just a two week period.

The owners are turning him out for a few hours each evening on old, long-stem pasture which Shadow loves. 

Reintroducing turnout means they have been able to cut back on some of the calories they were providing in his diet, and is likely to reduce the risk of Shadow redeveloping ulcers. Horses are designed to graze and forage for their food and while it can be necessary to hand feed them in order to control intake, for the sake of their long term health, the aim is always to get them back to grazing and foraging naturally as much as possible. 

MetaboLize® has been an invaluable tool in getting Shadow back on the right track towards being able to forage and graze actively again, and a  vastly improved quality of life. After all, this lovely pony has given joy to hundreds of children over a long career, and fully deserves his golden years to be comfortable, relaxing and fun.