Friday, May 10, 2013

Medicinal Leeches: The Much-Maligned Traditional Healing Aid is Making a Comeback for Equine Lameness Therapy

In this photo from German rehabilitation therapist Martina Mäter of Kathmann Vital GbR in Vechta, you see three colorful medicinal leeches hard at work. Lower-limb lameness is a common callup for leeches in the horse world; they may soon be in wider use in the United States. (Photo © Martina Mater, used with permission)

You're in a veterinary lecture on laminitis at a major conference on equine lameness. Set your watch to see how soon one of the speakers makes a wisecrack along the lines of "Yeah, sure, and we used to use leeches to treat laminitis, too." Cue: nervous laugh from the audience. Rolling of eyes. Wrinkling of noses. "Gross!" Shudders.

People don't even need to see a leech to be repulsed. We're hard-wired to recoil from the very idea of a living being intent on sucking blood.

The therapeutic value of leeches was first recorded in Egyptian times; it had a strong revival in the Middle Ages in Europe and returned again in the mid-1800s; this latest surge in interest and popularity for leech therapy follows the cycle.

In 2005, the General and Plastic Surgery Devices Panel (GPS Panel) of the US Food and Drug Administration (FDA) voted unanimously to approve the medicinal use of both maggots and leeches. The single caveat was that satiated leeches should, after removal, be considered a biohazard form of waste. Maggots and leaches became the first approved living medical devices in the United States.

Fine healthy leeches
In days gone by, you could purchase leeches at the drug store; that day might be returning.

While the use of sterile maggots for equine foot infections has been extensively detailed by Scott Morrison, DVM and others, the therapeutic use of leeches for horses has not been publicized.

Maybe that is because, simply said, no one likes leeches. If you've ever had a common bloodsucker latch onto you after swimming in a stagnant pool, chances are you didn't forget it. And you didn't go back there to swim ever again.

Hollywood hasn't helped the reputation of leeches either:

No one likes to even talk about leeches. No one, that is, who hasn't witnessed the benefits of using them. While that is much more likely to happen outside the United States, the importation of medicinal leeches from Europe has quietly begun here, and the push is on to change how people think of them.

Who can forget when 
leeches stole Humphrey 
Bogart's scene in 
African Queen
The use of leeches is known as hirudotherapy. It's important to understand that leeches don't just suck blood from their hosts; their suction fluids contain many different agents that may have therapeutic effects, as well as creating a circulatory event in an area adjacent to an injured or diseased part of the lower limb.

Proponents of hirudotherapy even claim that, in the wild, injured or lame animals will instinctively seek water infested with leeches.

Many people think that leeches would be used to "bleed" the horse; "blood-letting" would be done by controlled and intentional loss of blood. Leeches have a much more complex role to play.

The American Museum of Natural History (AMNH) hosts a "Leech Lab" that is investigating how various leech species work. While this is separate from the study of using medicinal leeches for therapy, the AMNH lab examines the symbiotic relationships between leeches and their hosts. One donates its blood; the other provides some chemical input that has therapeutic benefits.

But how much of this chemical input is enough? The leech is under the microscope and what many of their proponents have claimed for years may soon be fully understood.

The technique for applying leeches to wounded soldiers in the American Civil War is carefully detailed in the Manual of Directions for Nurses in Army Hospitals, published in 1861.

One of the many compounds found in the saliva of medicinal leeches is hirudin, a powerful anti-coagulant.

To gain some insight into medicinal leech use for equine lameness, The Hoof Blog went to an unusual source: an international dressage rider. Possibly the most cheerful advocate of leech therapy in the United States at present is Grand Prix rider Catherine Haddad, whose World Equestrian Games US Equestrian Team mount enjoyed the benefits of leech therapy for a suspensory ligament injury while training in Europe.

Catherine's video is a  reality-TV style introduction to the idea of using medicinal leeches for equine lameness. (Characteristic to her station in the horse world, Catherine immediately recognized the suction mouth of the leech as resembling a Mercedes-Benz logo.)

According to Martine, the therapist in Catherine Haddad's video, some of the equine lameness problems well suited to hirudotherapy include:
  • Tendonitis
  • Bruising
  • Abscesses
  • Edema
  • Thrombosis (blood clotting)
  • Poorly healing wounds
  • Acute laminitis
  • Scarring
  • Insufficient lymphatic drainage
The historical use of medicinal leeches for horses, particularly for laminitis, is not very well-documented, legendary as it is.

One aspect of leeches that is well documented is the detrimental effects of what were known as "horse leeches" but had nothing to do with therapy. A "horse leech" is indeed a type of leech, but it is not the type used intentionally for human or animal therapy.

According to a 1920 edition of Veterinary Notes for Horse Owners, Captain Horace Hayes describes the infestation of horses' mouths, nasal passages and even digestive tracts with leeches after they were allowed to drink from infested water, or after leeches dropped off the mouths and nasal passages of infected horses into common water troughs.

Book on horses, Removing a leech from a horse’s mouth, Walters Art Museum Ms. W.661, fol. 75a
A Turkish veterinary manual, circa 1300 AD, explains how to remove a rather large leech like this one from the leg of  a horse. (Walters Art Museum image)

Medicinal leeches were in such demand for humans in Europe in the 1800s that they became virtually extinct. Today, breeding and management for a steady supply of medicinal leeches is done in laboratories or controlled "leech farms". The US government even offered a $500 reward at one time to any American who could find a way to successfully breed medicinal leeches in this country; they all had to be imported.

Now that you have met the medicinal leech and seen it in action, how do you think this interesting creature can help you help horses? In part two of this article, The Hoof Blog will focus on recent work to document the use of medicinal leech therapy for laminitis.

Thanks to dressage rider (and veterinarian's wife) Catherine Haddad and the Chronicle of the Horse for the use of this video.

To learn more:

Medicinal leeches: historical use, ecology, genetics and conservation by J. Malcolm Elliott and Ulrich Kutschera, courtesy of the Freshwater Biological Association.

Leeches: Beneficial Bloodsuckers by Catherine Haddad Staller

 © Fran Jurga and Hoofcare Publishing; Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. Please, no use without permission. You only need to ask. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page). To subscribe to Hoofcare and Lameness (the journal), please visit the main site,, where many educational products and media related to equine lameness and hoof science can be found. Questions or problems with this blog? Send email to
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