Spring arrives, bringing warmer weather which allows the grass to grow. The horse or pony in the backyard who seems to be able to live on the smell of grass two miles down the road, founders with severe laminitis! Sounds familiar? Almost everyone has either experienced it or knows of someone who has. Laminitis is one the most common equine ailments in the modern era. So, what is the cause?
What is laminitis?
Laminitis is the inflammation of the laminae of the hoof – the soft tissue structures that attach the coffin (pedal) bone to the hoof wall. Without the coffin bone properly attached to the inside of the hoof wall, the weight of the horse forces the bone away from the hoof capsule (outside of the hoof), damaging arteries and veins thereby restricting blood flow to the sole and coronet. As the inflammation and damage to the laminae continues, the coffin bone slowly rotates down towards the sole of the hoof and, in extreme cases, can push through. The result is chronic (continual) pain and lameness. But what is the cause of this debilitating and obviously painful disease?
What causes laminitis?
Laminitis was originally thought to be a result of a grain overload in the hindgut resulting in acidosis or caused by a systemic illness or infection such as a retained placenta in a mare. These situations certainly cause laminitis in horses but they only account for about 10% to 20% of reported laminitic cases. The other 80 to 90% are a result of endocrinopathic (metabolic) causes, primarily insulin dysregulation (previously referred to as insulin resistance).
What is Endocrinopathic laminitis?
Endocrinopathic laminitis describes laminitis that develops in horses with endocrine (hormonal) and metabolic disorders. This includes laminitis that is associated with:
- Obesity
- Insulin dysregulation
- Elevated adrenocorticotrophic hormones (ACTH – stress hormones)
Three equine related diseases which are known to induce such symptoms are:
- Equine Metabolic Syndrome (EMS). Click here to read more about EMS
- PPID (Pituitary Pars Intermedia Dysfunction or Cushing’s disease)
- Insulin Dysregulation (ID). Click here to read more about insulin dysregulation
Each condition commonly relates to a consistently (chronically) excessive intake of energy in the diet, particularly in the form of non-structural carbohydrates (NSC = simple sugars and starches).
Where do the sugars and starches come from?
All horse feeds contain sugars and starches, including high roughage feeds like hays, chaff, and haylage. When digested in the small intestine, the sugars are released from the feed to enter the body as glucose. The easily digested (non-resistant) starches in the feeds are quickly digested within the small intestine and enter the body also as glucose. These are the starches commonly found in grains and grain-based feeds. The other more resistant (harder to digest) starches, more commonly found in low NSC hays and grasses, travel to the hindgut but are often used as a food-source for the good microbes there (as prebiotics). The result of digesting and absorbing the sugars and easily digested starches is consistently high levels of glucose in the blood.
How does the horse’s body respond to lots of glucose in the blood?
The common metabolic response to an increase in blood glucose levels is for the pancreas to release insulin to try and stabilise the glucose at safe, biological levels. When blood glucose levels are high for a long period of time, the pancreas continues to release more insulin, resulting in very high levels of insulin that don’t decrease back to a normal level. This is called hyperinsulinemia, the main cause of insulin dysregulation, and currently considered the main cause of laminitis in horses. In short, a laminitis-prone horse is a metabolically dysfunctional horse.
What are the signs of a metabolically dysfunctional horse?
There are several common clinical signs that suggest a horse is metabolically dysfunctional and likely to become laminitic. They are:
- Subtle, early changes
- Hoof wall distortion – changes in the hoof wall, such as toes that grow too quickly or are dished or flared
- Hoof rings – ridges around the hoof which are usually closer at the toe than the heel
- White lines – these lines are often stretched and are usually the earliest noticeable change
- Seedy toe or fungal infection – often a result of white line disease leading to a hoof infection
- Chronic foot abscesses – metabolically dysfunctional horses have a higher tendency to get foot abscesses throughout the year, especially spring
- Loss of appetite – often due to discomfort
- More advanced stage changes include
- Changes in normal gait/stride – a shortened stride, foot soreness, stiff head carriage, and a reluctance to trot on firm/hard ground
- Weight shifting – lifting their feet more than normal or a reluctance to lift their feet
- Generalised foot soreness – sensitive to having hooves cleaned and soreness after trimming or shoeing
- Digital pulse – an increased pulse of blood in the lower leg, flowing to and from the hoof which can be felt due to inflammation or restricted blood flow
- Increased hoof temperature – warmth felt inside the hoof capsule
- Increased insulin levels – a common indicator of hyperinsulinemia
- Obesity – a common condition of Equine Metabolic Syndrome and usually indicated by a score of 7+ on the Henneke body condition score chart
- Fatty deposits on the body – commonly seen as a cresty neck with fatty areas on the rump and behind the shoulder. For a better understanding of cresty necks and fatty deposits, read our article
How can you manage metabolic dysfunction in horses?
Diet, supplements, appropriate exercise, environmental changes, and veterinary guidance are all practical measures that you can incorporate to help manage the health of your metabolically dysfunctional horse.
Choosing a safe diet for a metabolically dysfunctional horse can be hard and complicated, therefore, we have developed a guide on how to feed a metabolically dysfunctional horse. With the help of your vet and a qualified equine nutritionist, the overall diet goal for metabolically dysfunctional horses is to minimise daily non-structural carbohydrate (NSC) intake. This can be by feeding low NSC feeds and also monitoring pasture access.
Targeted nutritional supplements designed for metabolically challenged horses can help support and enhance current management plans. A product like  has been formulated to support healthy metabolic function by addressing the biggest drivers of metabolic health.  PROTEKMDTM is designed to be a part of your horse’s management plan. Find out how PROTEKMDTM is a great fit for your metabolically dysfunctional horse.
Exercise is an important tool in managing the metabolically dysfunctional horse. Not only will exercise help control the horse’s weight, but it will also help improve blood flow to the hooves, including the laminae. This should help reduce inflammation and swelling. It is important to tailor the exercise program to match the condition of your horse, especially after a recent laminitis episode.
Always remember
Laminitis is a major debilitating disease mostly caused from the continuous excessive intake of readily digested sugars and starches in feeds. The result is a loss of the normal, controlled regulation of the metabolic system which helps maintain a healthy, active horse. Watching for the early signs of metabolic dysregulation are important but, should they appear, implementing a controlled management plan which includes diet changes, veterinary assistance, exercise, and pain management is essential. Including a targeted supplement like  PROTEKMDTM  may also assist in supporting horses with metabolic dysfunction.
It is important to always remember that not all metabolically dysfunctional horses will become laminitic, but all laminitic horses are metabolically dysfunctional.
