Equine Cushing’s Disease (ECD), Equine Metabolic Syndrome (EMS), and Insulin Resistance (IR) are three primary diagnoses associated with the risk of laminitis (defined as laminae separation and/or stretching). If your horse has been diagnosed with any one of these, he is at risk for laminitis. But do you know how much of a risk, and can you tell if or when your horse is actually going to have laminitis? Does one of these diagnoses imply more risk than another?
Careful management of your horse’s diet and exercise are used to limit risk, but when the degree of metabolic dysfunction is unknown, the prediction of laminitis is merely guesswork. Neither the diagnosis nor the external signs and symptoms can give a clear enough assessment of your horse’s particular health problems to predict laminitis.
But, fortunately, there is a simple, minimally invasive procedure that can: a blood chemistry report, or blood work. A good blood work report not only yields a predictive index of your horse’s risk for laminitis but also offers a comprehensive picture of the other health issues that accompany these metabolic dysfunctions. While watching the external signs and symptoms is important for daily safeguarding, only through blood work is it possible to track the progression or recovery of the underlying metabolic process with accuracy.
Predicting Laminitis: Familiar signs and symptoms vs. blood work profile
Familiar signs and symptoms:
Fat deposits in the rump, over the eyes or on the shoulders, a cresty neck, “hay belly,” polyuria, (urinates a lot), polydypsia (drinks a lot), long curly thick coat that doesn’t shed “properly” are the most familiar. Some of these signs and symptoms may be present in a horse regardless of the diagnostic label. All of them can indicate metabolic dysfunction but none of them are directly indicative of an impending laminitic episode. By themselves these “external” signs and symptoms do not have significant predictive value.
Blood work profile:
Blood work profiles offer an effective and affordable laminitis predictor. Since blood chemistry reports have become more common as a diagnostic tool for the field vet., specific blood tests have been chosen as “standards” to determine metabolic dysfunction related to the risk of laminitis. The blood tests that are used as indicators of predictive value are ACTH (adrenocorticotropic hormone of the pituitary gland), T4 (a thyroid gland hormone), cortisol (a glucocorticoid secreted by the adrenal gland), and insulin (a protein hormone secreted by the beta-cells of the pancreas).
A recently published and well designed research study investigated, for the first time, whether these specific blood tests are correlated with laminitis. 1 The results were strikingly clear. Elevated insulin levels were “highly” correlated with laminitis: the more elevated the insulin concentration, the more likely a laminitic event would occur and the greater the damage there would be to the hoof. This was found in the study’s ECD horses as well as the EMS horses since all had elevated insulin levels. Although the study divided horses into ECD and EMS as diagnostic groups, the results demonstrated that IR was the underlying issue common to each group. IR is defined, through blood work, as “normal” serum/ blood glucose (euglycemia) and elevated serum insulin levels (hyperinsulinemia).
All of the horses studied were either currently laminitic or had a history of laminitis. The ECD horses all had elevated ACTH levels; none of the EMS horses did.
The ECD horses were given daily pergolide treatment for twelve months to analyze the results of lowering ACTH levels on laminitis risk and hoof damage. ACTH levels lowered within the first week of pergolide administration and then remained constant for the rest of the twelve months of giving this drug. There was no correlation between the ACTH reduction and laminitis risk nor did lowering ACTH levels influence the magnitude of hoof damage. The risk of laminitis remained highly correlated only with elevated insulin in all horses despite the initial drop in ACTH levels.
T4 levels had a weak inverse relationship with insulin; i.e. higher insulin correlated with lower T4 levels but T4 changes also did not correlate with laminitis, nor did “fluctuations” in cortisol levels.
The Relevance of Insulin Resistance and a Comprehensive Blood Chemistry Report
IR was the primary connection between all ECD and EMS horses in the research investigation since every horse in these two groups had elevated insulin levels. IR is known to be a progressive metabolic dysfunction. 2 As IR progresses, a number of health problems other than laminitis develop, e.g. immune deficiencies, vascular difficulties, anemia, gastrointestinal disorders, and acid-base disorders (involving extremes of pH). The only way to detect these health problems is through a comprehensive blood work profile: a CBC with differential count, a complete liver panel including serum glucose, and serum insulin. The common tests have no predictive value; these have predictive value and much more.
What are the practical applications of this study’s results?
The most essential point to be taken from this investigation is that testing for insulin levels through blood work is the only predictive test, of the ones investigated, for laminitis and the extent of associated hoof damage. It was also found that the severity of laminitis, i.e. hoof damage, decreased with decreasing insulin levels, making it imperative to determine as early as possible the baseline insulin level.
Because all EMS horses and half the ECD horses had a cresty neck and the combined group had elevated insulin levels, a cresty neck may be considered an “associated” indicator of laminitis risk. As horses without a cresty neck also had elevated insulin levels, a cresty neck cannot be considered an accurate predictor in and of itself.
Blood work should be done whenever a horse is considered to have IR and this should be done as early as possible, hopefully before a laminitic episode. Any and all the signs and symptoms are considered worthy of getting blood work for a horse. Follow up blood work should then be done every six months to examine the progress or recovery of the IR course.
If a horse “lives” at the very early aspect of IR, it is quite possible to reverse the IR course through the correct diet and movement program just as it is in humans. When a horse is beyond this early phase, the only method I know that has an effective track record is my herbal solution program appropriate for that horse’s degree of IR.
Laverne’s Recovery: An example of the benefits of a comprehensive profile
Laverne had been unable to stand for weeks following an acute laminitic episode. The sores seen on her right hip area in Photo 1 are a result of Laverne not being able to get up or roll off her right side.
Her owner, Linda, asked her vet to do a complete blood chemistry report including the test panels previously described in the Relevance of Insulin Resistance section and requested an analysis of the findings from the author. The blood work showed that Laverne was suffering from not only IR but also a life threatening acid-base disorder referred to as a high-anion gap metabolic acidosis (a category known as lactic acidosis) brought about through oxidative “stress” (deficiency of oxygen) in the most severely damaged hoof.3
In addition she had a massive bacterial infection stemming from her hip sores and the hoof abscesses that followed the laminae separation. These serious and painful consequences had suddenly progressed Laverne’s IR to a level where her glucose was significantly elevated (hyperglycemia), which is medically defined as type 2 diabetes. Along with her hoof oxidative “stress” was a change in the viscosity (thickness) of her circulating blood, depriving her hoof of necessary blood and nutrients; further complicating her prognosis.
From this information the author was able to recommend an initial program of select Chinese herbal solutions and Linda began administering them immediately. Within three days Laverne got up and remained standing. The author recommended follow up blood work profiles and made adjustments in his herbal solution program for Laverne based on the findings in these subsequent blood panels and ongoing communication with Linda.
Photo 2 was taken five months and one week after Photo 1 and all of Laverne’s blood work abnormalities were now within the healthy normal range and she was up and about with quality of life.4 The blood work no longer displayed Type 2 diabetes or IR.
The information obtained from the series of comprehensive blood work reports was indeed very beneficial.
1. Correlation of Plasma Insulin Concentration with Laminitis Score in a Filed Study of Equine Cushing’s Disease and Equine Metabolic Syndrome. Walsh, D.M., McGowen, C.M., McGowen, T., et.al. Journal of Equine veterinary Science, Vol 29, No 2, p 87-94, (2009).
2. Insulin Resistance and Insulin Secretory Dysfunction are Independent Predictors of Worsening of Glucose Tolerance During Each Stage of Type 2 Diabetes Development. Weyer, C., Tataranni, P.A., Bogardus, C., Diabetes Care, Vol 24, No 1, p 89-94, (2001).
3. Clinical Biochemistry of Domestic Animals. Academic Press, Kaneko, J.J., Harvey, J.W., Bruss, M. L., p 585-516, (1997).
4. Laverne’s blood work information was taken from the author’s data base of approximately three hundred blood chemistry reports for horses labeled ECD, EMS, IR, and/or laminitis.