Horses today live longer than in years gone by. Which is wonderful.
However, living longer can bring about health issues that than we didn’t need to consider in the past, and although this isn't the main reason, the pituitary gland and endocrine system can be adversely affected, and bring on health issues that than we didn’t need to consider in the past, specifically Cushing's Disease, aka Pituitary Pars Intermedia Dysfunction (PPID).
Our own experience with Cushings came out of the blue. Several years ago on his daily walk, our daughter’s elderly pony, Dinky, suddenly presented seriously lame with his breathing worryingly laboured – all the signs of laminitis. This literally happened overnight - the previous day he'd been fine; the next, he wasn't. Although we instantly addressed his symptoms, there were other signs that we'd begun to notice - we hadn't had him long and were still getting to know him, but we were approaching summer and his winter coat wasn't shifting, and he was noticeably drinking and urinating more. We suspected Cushings and got him tested; it came back positive.
Cushing's Disease, aka Pituitary Pars Intermedia Dysfunction (PPID), is all about hormones going wonky. Cushing's is a dysfunction of the pituitary gland, which causes hormonal disturbances. The Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary, and the region which controls the functioning of the secretory cells. It relies on dopamine as its neurotransmitter (a chemical messenger that helps in the transmission of signals in the brain and other vital areas) to regulate secretions.
As horses age, and just as it does in humans, the decrease in dopamine occurs naturally. As the older horse becomes susceptible to the loss of dopamine, the Pars intermedia produces an excess of hormones, including the hormone ACTH (Adrenocorticotropic) which stimulates the production of cortisol, a stress hormone produced by the adrenal gland.
And so begins the metabolic effect
As if managing the other symptoms of Cushing's isn't a juggling act enough, Cortisol increases sugars in the bloodstream and enhances the brain’s use of glucose. Just as in us humans, when the horse is anxious, the system sends signals to the adrenal glands to release adrenaline and cortisol. While the fight-or-flight reaction of the body stays active, cortisol continues to release sugars into the bloodstream.
Here come the side effects of high cortisol levels - we're looking at weight gain, insulin resistance (IR) and abnormal glucose metabolism, all the precursors to metabolic laminitis. It’s a vicious circle - as cortisol levels increase, insulin levels must then increase to try and keep glucose within what the body thinks are ‘normal’ levels. In humans, we call chronic, unregulated levels of insulin ‘diabetes’.
ACTH levels are also renowned for increasing around Autumn when the days become shorter and the body’s natural hormone levels change, in response to the system’s natural Circadium Rhythm (the 24-hr cycle in the physiological process of all living beings, determining sleeping/feeding patterns, brainwave activity, hormone production, cell regeneration and other biological activities).
Getting the PPID/IR/EMS controlled and managed is essential in order to minimise the associated laminitis risk. There's a saying out there that says, 'not every laminitic horse gets Cushings, but every Cushings horse will get laminitis.' There is no cure for Cushing's, but controlling the cortisol levels restores the insulin response, and this is a great starting place. There is light at the end of the tunnel though; once PPID has been diagnosed, management is do-able, albeit a constant work in progress, but your horse can return back to a comfortable lifestyle.
Lower Cortisol & Increase Dopamine Levels Naturally Stress and certain health conditions can raise cortisol, lower dopamine levels and cause weight gain. Keep levels balanced by exercising, allowing rest, maintaining a happy equilibrium, feeding a natural, appropriate diet and adding a vitamin/mineral supplement that support healthy cortisol and dopamine levels.
Exercise is really important, not just to rid the body of fat cells, but it's also proven to increase dopamine levels. Regular exercise also helps to burn the extra blood sugar made available through elevated cortisol levels.
In addition to the countless physical benefits, exercise can also have psychological benefits. Studies show that exercise can increase the amounts of both dopamine and serotonin neurotransmitters in the brain, as well as helping your horse feel more energised overall.
In a May 2007 article in the ‘Journal of Neuroscience’, it was noted that exercise could cause the brain cells that use dopamine to work more efficiently. The study shows that the dopamine-releasing neurons of rats who ran on a treadmill, released more dopamine than rats who did not exercise, with the dopamine remaining active for longer in the treadmill rats.
It was also noted that continuous exercise also reduced damage to brain cells that release dopamine. In an August 2007 article in the journal ‘Neuroscience Letters’, it was reported that the treadmill rats that exercised for 30 minutes a day for two continuous weeks, lost less dopamine-releasing cells than non-exercising rats.
Quality Rest Time helps lower cortisol levels because otherwise the body’s nervous system stays in a state of alertness that requires cortisol. Getting proper rest also increases serotonin and dopamine, which help control feed cravings.
Feed Omega-3 Fats Omega-3 fatty acids help trigger the production of serotonin, as well as being a good food source of the trace mineral selenium. A low intake of this mineral has been linked with depression (see our BareEssential Conditioner).
Brewers Yeast Adding Brewers Yeast to the diet is also extremely beneficial. Brewers Yeast provides the full compliment of the B-vitamins which are immensely valuable to the metabolic horse, and can help lower cortisol levels (see our BareEssential Conditioner below).
Steps you can take to lower cortisol and stimulate dopamine levels naturally:
Useful Herbs to maintain the Endocrine System
~ Agnus Castus - The most distinctive feature of Agnus Castus is that it has a positive rebalancing hormonal effect on the body, and specifically on the pituitary gland, with evidence showing that it has proved effective for early stage cases of Cushing’s syndrome. The UK Horse Journal ran a field trial of Vitex including 10 horses and ponies, the subjects aged between 13 and 25 years, diagnosed with Cushing's or demonstrating the classical Cushing's symptoms. The Journal reported that typical response was 'rapid and dramatic'. Shedding of the coat typically began within three weeks, and energy levels quickly increased. High blood glucose and insulin levels dropped in some cases within four to six weeks.
~ Dandelion - A general stimulant to the system, but especially to the urinary organs, and promotes liver detoxification. Potassium-rich dandelion has been called the "free health food pharmacy" with both leaves and roots considered to act as a superior natural diuretic, digestive aid, mild laxative, fine blood cleanser and nutritious tonic.
~ Goat's Rue - Helps relieve the symptoms of diabetes mellitus in humans, and the precursor of Metformin (Glucophage), currently recommended as the first choice for anti-diabetic pharmacotherapy alongside diet and exercise. Contains compounds related to guanidine, a substance that decreases blood sugar by mechanisms including a decrease in insulin resistance.
~ Golden Rod - Considered an excellent support for kidney and bladder health.
~ Ginkgo Biloba - Infamous for general longevity and specifically for enhancing circulation, ginkgo is known to relieve age-related declines in brain function, and is thought to be the world's most used therapy for maintaining healthy brain activity and central nervous system function. It increases the circulation of blood and oxygen to all parts of the body, and is an effective overall tonic, and consequently overall improved metabolism.
~ Liquorice - Liquorice has a particular affinity with the adrenal glands making it a very useful herb with its anti-inflammatory, anti-allergic and anti-arthritic effect similar to that of cortisol but without its side effects, due to its active component 'glycyrrhizin' which has a structure similar to hormones produced by the adrenal glands. Thus, when Cushing's is present liquorice can help rebalance the hormone production from the adrenal glands.
~ Milk Thistle - For its protective effects on the liver and to greatly improve its function. This remarkable herb is said to have no pharmaceutical equivalent for its beneficial effects on the liver, ridding the system of toxins, boosting immunity and providing valuable antioxidant protection.
~ Nettle - Mineral and vitamin-rich nettle is a naturally nutritious way to help maintain a healthy urinary tract and flush toxins from the system, said to uplift a weary body, reduce fatigue and also improve thyroid, kidney and bladder functions.
~ Yarrow - A wonderful toning and diuretic herb which acts as a system purifier.