Dr Tom Shurlock, consultant nutritionist for British Horse Feeds, discusses laminitis and the compromised horse; horses that suffer from Cushings, Insulin Resistance (IR) and Equine Metabolic Syndrome (EMS).
Laminitis is the result of many additive factors. At springtime the attention is on sugar levels in spring grass, where too much is reaching the hindgut can lead to microbial disruption, toxic end-products being absorbed (helped by lactic acid “opening up” the gut to larger molecules); these add to inflammatory components in the hoof region, leading to degeneration of the lamellar and, ultimately, coffin bone disengagement. The simplest action is to reduce intake of sugar/starch to avoid this happening.
However, there is a metabolic route that can occur in compromised horses, those suffering from IR, EMS & Cushings (PPID).
What happens to sugar in the horse’s body?
The mechanism of sugar metabolism is fairly straight-forward. Simple sugars & disaccharides (two linked sugar molecules, such as sucrose – glucose & fructose) are absorbed from the small intestine; insulin is released that increases the permeability of cells, so sugars can be directed to the mitochondria and start the process of generating energy. Any sugar, excess to requirement is either stored in the muscles as glycogen, or converted into fat by various biochemical pathways. It is reasonable to assume that, where excess sugar is reaching the hindgut, then absorbed glucose must be high, and this could lead to, at best, a fat horse. But what happens when the horse is compromised?
Which conditions can disrupt how the horse processes sugar?
There are a number of conditions that centre around the dysregulation of sugar metabolism, in particular the efficacy of insulin. PPID is an example of this.
Why does this lead to laminitis?
PPID, or Cushings, is a condition, increasingly likely with age, where there is a loss of endocrinologial regulation of a portion of the pituitary gland. This leads to excessive secretion of pituitary gland hormones, one result of which is hyperglycaemia (excessive blood sugar). At the same time compromised cortisol binding can lead to insulin dysregulation; the result of these two factors disrupts the normal metabolism of sugars. Instead of entering the cells, glucose circulates in the blood stream and pools where blood pressure is weakest – in the hooves. At the same time the mitochondria are starved of their energy source, resulting in hypoxia, reperfusion and the release of inflammatory factors.
At the same time PPID is associated with an increase of the inflammatory agent Il-6, its levels in the blood increasing with age. This low level of inflammation further aggravates areas where the cues are not readily flushed away – again, the hooves.
Manifestation of other conditions through a reduction of insulin sensitivity, whether IR or EMS, and an increase in inflammatory factors, also fit with the horse’s susceptibility to laminitis.
At the hoof level, therefore there is a situation where hypoxia (oxygen starvation to the cells), inflammatory cues (internally derived by disorder, or externally by hindgut dysfunction) and blood pooling all act directly on hoof condition and oxidative damage, resulting in inflammation, and destruction, of the laminae and lamellar breakdown – Laminitis.
What other factors can lead to laminitis?
Whilst the major route of dysfunction is through the excessive intake of starch and sugars (starch being long chains of the sugar glucose), or the dysfunction of insulin (which also impacts stomach acid secretion- affecting microbial populations further down the line), there are other factors that add to the likelihood of laminitis – lack of exercise, fat deposition etc. – some or all of which may be accentuated in compromised horses, so the roles of exercise and nutrition can help lessen the impact.
Gentle exercise will help improve circulation, and this will avoid blood pooling and flush away negative factors, whilst nutrition must address the oversupply of sugars.
The horse evolved to make use of the sugars that make up fibre. As animals don’t have the enzymes that break the beta links, they host microbes that do the job in their guts that can breakdown sugars to smaller molecules. These end products – the VFA, or slow- release energy – are absorbed, pass easily into the mitochondria and enter the energy release system further down the biochemical chain than absorbed sugars. Interestingly, one VFA, propionic, can actually be recombined into glucose, which is an essential nutrient, and still avoid insulin release.
As such they do not impact on insulin release/sensitivity and would help reduce some of the stresses on the generation of laminitis. It is an extremely complex interaction of causative agents but reducing one line may raise the threshold and reduce the impact of laminitis and restricting sugar intake is a major modulating route. If energy supply then becomes a problem, the inclusion of super fibres rather than added oil again will help avoid insulin regulated mechanisms (insulin is actively involved in fat deposition and the release of adipokines – inflammatory agents).
Laminitis can “hit” through a number of mechanisms, probably through several simultaneously but, by reducing the impact of the central route – oversupply of sugars for a specific condition – chances can be reduced.
Spring Feeding with Speedi-Beet & Fibre-Beet
Speedi-Beet is a highly nutritious micronized (cooked) beet pulp feed which provides an excellent source of digestible fibre and is ideal for equines prone to laminitis as part of a balanced diet.
Due to its unique manufacturing process, Speedi-Beet can be soaked and ready to use in just 10 minutes and is extremely palatable. It is also starch free and unmolassed, making it up to 95% sugar free.
Feeding Speedi-Beet before turnout can help stabilise the ingestion of sugars present in spring grass.
Speedi-Beet is also extremely versatile. It can be fed in small amounts to overweight horses as a carrier for a multivitamin and mineral supplement or in larger quantities to a poor doer for weight gain, or working and competition horses that need extra energy.
Fibre-Beet is a formulated blend containing all the benefits of Speedi-Beet with added high quality Alfalfa for optimum condition and to provide quality protein for muscle tone and function. Alfalfa can also help with topline or simply help maintain weight and a healthy, shiny coat.
Like Speedi-Beet, Fibre-Beet can also be fed to horses and ponies prone to laminitis as part of a balanced diet.