Casner: Studies Show Some Therapeutic Medications Do More Harm Than Good

Arthur Hancock’s powerful Op-Ed challenge “If Not Drugs, Then What is Causing Fatal Injuries?” spurred me to share some science that in my opinion makes the answer blatantly obvious.

Recently, in preparation for a meeting, I gathered studies and data off of PubMed (National Public Medical Library) that pertained to  “therapeutic meds” that we routinely administer to our racehorses.

I previously researched this subject about nine years ago when I chose to stop using Lasix and Bute on my horses but I was staggered by the increased volume of human studies and data that showed how derogatory loop diuretics (Lasix) are to bone metabolism and how significantly they INCREASED FRACTURE RATES. I counted 48 studies that ALL implicated loop diuretics with INCREASED FRACTURES.

Lasix causes a massive calcium flush along with several other electrolytes. Homeostasis of calcium has to be replenished quickly for nerve transmission and muscle contraction, especially cardiac. In order for this to happen, calcium is pulled from the bone to re-establish that critical balance.  Every time Lasix is administered the derogatory effect on bone and recovery are virtually ignored.

Next I researched Proton Pump Inhibitors (Omeprazole aka GastroGard). As all owners are aware by our vet bills, many horses at the track receive a full or half dose of GastroGard on a daily basis as a “preventative” for stomach ulcers. Again, there were countless (I stopped counting at 50) research papers filled with data that showed that PPI’s significantly INCREASED FRACTURE RATES. This recognition has caused the human medical community to dramatically reduce usage.

Last, I examined the data on the administration of Thyro-L, which is the synthetic thyroid hormone Levothyroxine. Thyro-L has routinely been administered daily by many trainers in the feed of their horses. Levothyroxine is a powerful metabolic regulator and when given to young horses speeds up their metabolism and makes them more precocious.

There are several problems with administering Thyro-L. The first is that the thyroid gland and the exacting release of its hormones are critical to a horse’s health. When it is administered continually, it causes hyperthyroidism and produces “Negative Feedback” that shuts the thyroid gland down. Long-term use causes it to atrophy and eventually quit producing it own hormones – very bad for a horse’s health.

But MORE IMPORTANTLY, the medical literature is overwhelming in stating the adverse effect of high metabolic levels of Thyroxine on bone is INCREASED FRACTURE RATES.  Why is the administration of this powerful hormone still allowed????

For decades, we have used human medications to treat our horses without any studies to establish if there are any detrimental side effects of continual usage.  We focus on one narrow therapeutic benefit and ignore the litany of detrimental side effects. There are stacks of clinical data showing furosemide use in humans INCREASES FRACTURES.

The leap to horses is an easy one. The bone of horses and humans is virtually the same and the remodeling process in both is identical.  Chronic Lasix usage interferes with bone remodeling and per the science is a significant contributor to FRACTURES. When we combine it with the daily use of GastroGard and Thyro-L, all with volumes of data showing their derogatory effect on bone, we have a perfect storm that logically tells us that WE HAVE CREATED THE PROBLEM.

The survival of our industry is precarious. The world has changed and unless we are willing to make the health and welfare of our horses paramount, then we are doomed to a continual decline and possible extinction. Today’s world has no tolerance for what is perceived as abuse to animals and medicating our racehorses to run, certainly contributes to that negative perception. The cold hard fact is that racing medications can be abusive. The science and data is unequivocal in showing that these meds individually, and when stacked on each other, significantly weaken bone causing INCREASED FRACTURES.

Yet, we ask the question and scratch our heads wondering why horses are breaking down. We are an industry of ostriches burying our heads, choosing to ignore the obvious and what the science speaks.

As a proverb states: “A Little Knowledge Is a Dangerous Thing.”

Bill Casner is a Thoroughbred owner and breeder

Bibliography Links
Loop diuretics (lasix) and increase fractures>


Proton pump inhibitors negative effect on bone (GastroGard)


Thyro-L  aka Thyroxin, T4 increased fracture rate-

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