Blood Viscosity and Colic
Colic is the leading cause of premature death in horses. The symptoms of abdominal pain we observe with colic can result from a variety of different causes.
We already know that horses engaged in even moderate levels of exercise trigger their natural blood boosting capacity, releasing blood reserves from their spleens. This increases oxygen carrying capacity but, at times, also makes the blood dangerously thick. When blood viscosity increases, the blood becomes thicker and stickier, and it is more likely to restrict blood flow and form clots in small vessels and capillaries. These are the vessels which are most affected in horses with colic caused by ischemic intestinal disease.
In this featured article, we ask: What is the relationship between blood viscosity and colic? What does the research show?
An earlier study conducted by veterinary researchers at the University of Tennessee examined this link, focusing on horses with colic undergoing surgery.
The Dangers of Overtraining, Part 2
Most trainers recognize that there are risks to overtraining their horses, but what should they do about it? In this article, we highlight recent research on high-intensity interval training, a regimen that is used to mitigate the risks of overtraining. A careful look at the science shows that it is not the duration of exercise but rather the intensity of exercise that has the most profound effect on the horse’s performance.
Although further research is necessary, the studies conducted to date clearly show that high-intensity interval training may actually impair a horse’s performance, yielding poorer training results. Pushing horses to maximal levels of exercise during training a little less frequently may not only improve performances but also the health and lifespan of the horse.
The Dangers of Overtraining
Previously at Equine Health Labs, we have described the effect of dehydration on the blood of exercising horses. The horse squeezes out as much as 12 liters of concentrated blood, which is held in reserve in a horse’s spleen, into its blood vessels.
In this new featured article, we offer a perspective on the dangers of overtraining horses, focusing on how a horse’s blood boosting ability can make it more vulnerable to overtraining.
Lasix and Blood Viscosity
One of the questions that we are frequently asked is, “What is the effect of Lasix on blood viscosity?”. Bleeds, or exercise induced pulmonary hemorrhages, affect the majority of horses during intense exercise, and for the past 40 years, Lasix has been administered to horses before races as a way to reduce or prevent bleeds.
Lasix (or furosemide) is a potent loop diuretic that increases urine production and urinary frequency. Because Lasix reduces plasma volume, it is believed by many experts to reduce blood pressure in the lungs and prevent bleeds from occurring.
Most veterinarians, trainers, and horse owners have their own view on Lasix. Some research studies demonstrate that Lasix is effective for reducing bleeds, while other studies show conflicting results.
This article highlights some of the scientific literature on the effect Lasix has on blood viscosity in horses.
The Cause of Lameness in Horses
Lameness is a term that it used to describe a group of disease states that include laminitis and navicular disease. These are important problems for horses, problems that are widespread and very difficult to treat. Lameness is not limited to any one segment of the equine population. However, since lameness is the most common cause of training failure in racehorses, its impact is especially dramatic in the racing arena.
On March 24, 2012, the New York Times published an extensive report of a growing problem in the racing industry, describing numerous heart-breaking incidences of injured horses with broken legs, causing great risk not only to horses but also to jockeys. The use of pain-reducing medications for sore legs was also reported to be a widespread and growing concern.
Disturbed blood circulation is generally accepted as the root cause of lameness in horses. In the case of laminitis, if blood is unable to reach the legs and hooves of horses efficiently, the connection between the hoof wall and coffin bone becomes inflamed, and the bonds holding tissues together are destroyed. In general, lameness is a condition that can be monitored and treated by testing and improving blood flow.
Insights on Dehydration in Horses
Preventing dehydration is more than just a matter of quenching thirst. Staying well-hydrated means maintaining the delicate balance between the plasma and cells in the blood. Through regular exercise, both equine and human athletes train themselves to stay better hydrated. Their bodies adapt to exercise by increasing plasma volume. However there is another important factor at play.
In both horses and humans, exercise increases the demand for oxygen at the muscles and organs. To meet that demand, the spleen contracts to provide extra red blood cells to carry oxygen. For humans, there is an approximately 10% increase in circulating red blood cells. For horses, the increase is about 50%, which can cause an unhealthy surge in blood viscosity—the key difference in horses that makes them susceptible to more dangerous levels of dehydration.
Beware of Bad Blood: Insights on the Blood Reserve in the Spleen
At Equine Health Labs, we have been highlighting the fact that horses are natural blood boosters. The idea that dumping half a gallon of extra red blood cells into the blood makes the blood dangerously thick is intuitive. But what is less obvious is that the extra blood stored in the spleen is usually bad blood—blood cells that are stiffer and cause greater problems than normal cells.
Red blood cells must be soft and flexible in order to flow through the blood vessels, especially capillaries, which are at the last leg of the circulatory system before oxygen is delivered to muscles and organs. If red blood cells are not flexible, there will be an increase in pressure and friction, which leads to reduced aerobic performance and sometimes complete blockage of capillaries. The best way to detect this problem is to test for blood viscosity.
Why Do Horses Bleed?
In this article, we use a simple illustration to shed light on what causes bleeds in horses. Blood flow is important to circulation, health and athletic performance, and the dynamics of blood flow are easy to understand. The key point is just how dramatically a horse’s blood changes during intense exercise.
Exercise-induced pulmonary hemorrhage (EIPH or “bleeds”) is a condition that affects about 80% of racehorses. Since only about 1% of racehorses actually bleed out through the nose, endoscopes are often used to diagnose this common problem. In this featured article, we review scientific publications that explain the root cause of bleeds.
Sticky Blood in Horses
Most people in the horse industry know that horses are natural blood dopers. This is because horses hold a reserve of red blood cells and release the extra cells as soon as they start running. This quality has been established as a key trait that enables horses to be superior athletes.
What is not well-known is that the horse's red blood cells also behave differently than other animals. They are stickier. Studies have shown that a horse's blood cells are actually stiffer and much stickier than those of other animals, including humans.