The Misdiagnosis of DSLD and Injury in the Peruvian Horse.


Committee members:
Rich Ovenburg, Carol Borden, Tina Woodworth, Carol Hayden, Bill Chase.

( words in purple italics is added and not part of the original document)


The purpose of this report is to alert both Peruvian Horse owners and veterinarians of the reported growing incidence of misdiagnosis of Peruvian Horses. Because of the increasing proliferation of misinformation, some veterinarians are applying a different standard to the Peruvian Horse when diagnosing routine injuries. We also want to provide information to owners about some of the most common equine injuries and their effects, in order to assist them in seeking diagnosis and treatment for horses that may have been injured.

Disease: Illness or sickness often characterized by typical patient problems or symptoms and physical findings or signs. Any condition that prevents the body from working as it should other than direct injury.

Injury: May be applied in medicine to damage inflicted upon oneself or someone else. The term "injury" may be synomynous with the wound or with trauma.


The Peruvian Horse breed in the United States has done such a good job of making the general public aware of DSLD that it has become, in many people's minds, the number one characteristic associated with the Peruvian horse. Peruvian horse owners have spent close to three-quarters of a million dollars in the last six years to discover just what DSLD is, with very little success. The fact is, DSLD has not even been scientifically isolated as a disease.

In the latest privately-funded research from the University of Georgia, ( see attached charts#1) that cost the Peruvian Horses breeders over two hundred thousand dollars, bio-chemist Dr. Jaroslava Halper, writes about how they "suspect" an accumulation of "unidentified proteoglycans as being the cause of DSLD. However, on closer examination, there is as much accumulation of this proteoglycan in the connective tissue of the unaffected Peruvian control hose as there are in the affected ones. A nuchal ligament test that a worldwide press release claimed was successful turns out to test positive in six of the seven unaffected control horses! No one seems quite sure what the normal level of this proteoglyan is because it is yet to be identified. Proteoglycans occur naturally in connective tissue and are beneficial in healing injuries/ they have never before been associated with disease in equines. The use of glucosamine can raise the level of proteoglycans by over 150% in some horses, making this study even more confusing.

A quarter of a million dollars was spent by Peruvian horse breeders on a two-year genetic study, completed at the Univeristy of Kentucky in 2005. Researchers found no genetic cause or link between the affected and unaffected horses they were given. Dr.Cothran's co-researcher Kathryn Graves states, " Initial results identified a promising area containing several genes associatedwith ligament structure. However further testing did not support any of these initial findings." And yet, we still hear from many people talking about having a genetic test and isolating the DSLD gene. Dr. Cothren would, of course, like more money to try again. However, the real fact of this issue is, scientists would first have to discover what causes DSLD, before the gene could be isolated.

The most widely-read study ( see attached study #2: Veterinary Database Search) used to prove the Peruvian Horse has a higher incidence of this "disease" than other breeds, was actually a veterinary data search for suspensory ligament injuries, - not disease or DSLD- over a ten-year period from 29 veterinary hospitals across the United States. They found only 24 reported suspensory injuries in Peruvian horses from 1987 to 1997 or a little more than two a year, compared with 707 of these injuries for Standardbreds, 469 for Thoroughbreds and 443 for Quarter Horse. Though this study claims that these injuries are codes for disease and tries to relate these injuries to the population of Peruvian horses, there is absolutely noting in this study that relates these injuries to the general population.

However, Dr. Jeanette Mero, ( see attached letter ##) still used this study to solicit funding from Peruvian horse breeders and validate her claims that the Peruvian Horse breed was "predisposed" to this condition, completely ignoring the nine other breeds that had many more of these types of injuries than the Peruvian horse. Even though the veterinary data search was for injuries, Dr. Mero's study of twenty Peruvian horses gives no consideration to injuries, hoof care, conformation or nutrition deficiencies and assumes these horses have a disease that she states "is particular to the Peruvian Horse.". This misleading-study can be found in several places on the internet today and has been the constant source of confusing and negative articles about the Peruvian Horse.

The fact is, we really don't know any more now, than we did seven years ago. All the researchers, in order to get funding have promised a test" the protocol from Dr. Mero, a DNA test from Dr. Cothren, a nuchel ligament test from Dr. Halper. However, so far, there is no test. As Dr. Halper clearly states in he 2006 study "Presently, there is no reliable method of diagnosing DSLD in asymptomatic horses."

So what have we purchased with all our time and money? We now have a public relations disaster of such gigantic proportions that it threatens the very existence of the Peruvian horse breed in the United States. At a recent all breed equine fair in California 80% of the questions about Peruvian Horses were about the "Peruvian horse leg disease." A researcher at the University of Kentucky was "confidentially" told that some ranches had 40% of their horses affected with DSLD. Paso Finos and other gaited breeds are warning people not to buy our horses because "most Peruvian Horses have DSLD, and all the bloodlines are all infected." Dr. Jeanette Mero, who is described in the American Association of Equine Practitioners magazine as "an activist in promoting DSLD," has written several articles, for major equine publications unfairly connecting this condition with the Peruvian Horse . These articles claim, with absolutely no proof, that the Peruvian Horse is "predisposed" to what is described as an incurable, deadly disease, rampant in the bloodlines of our horses. Many of these publications are delivered free to veterinary clinics across the country and in some cases they go around the world.

While other gaited breeds are growing and enjoying unparalleled financial success including the Peruvian Horse in Central America and in it's native country of Peru, this negative publicity has had a drastic effect on our numbers here in America. We now have only 1200 two, three and four year old registered Peruvian horses in the United States compared to 2200 eight, nine and ten year olds. This means that in three years we will be trying to support our shows and a $300,000 NAPHA budget, with half as many horses.

This negative publicity has, of course, reached the veterinarians, who diagnose our horses and thing of DSLD with regard to every Peruvian horse they examine, along with a horse-owning public who now thinks every abscess or swollen fetlock in a Peruvian horse is DSLD.

The following are some actual case histories of how this results in the misdiagnosis of our horses. We picked these three cases out of the many we have received information on, because w could document their stories and also because some of the members of this committee have had similar experiences with this kind of misdiagnosis


Case #1

Gloria Eby had shoes put on her six year old trail riding gelding for the first time in his life. And now he was lame and she was worried.

A well-known lameness clinic was only a mile or two away from her boarding stable, so she took her gelding there and ultrasounds were done. The veterinarian had no experience with Peruvian horses so he sent the untrasounds to Dr. Jeannette Mero for a second opinion. They came back confirmed positive for DSLD. Gloria was shocked and heartbroken. The vet wrote a full-page diagnosis explaining DSLD and informing her that the prognosis was eventual euthanization. Gloria was grief stricken, gave the hors away; she cold not bear to have him put down and couldn't afford to keep a horse she couldn't ride.

The new owners treated the gelding as in injured horse and took one year to rehabilitate his injury. They sent the untrasounds to their veterinarian and to a clinic in California without revealing the breed of the horse. The diagnosis from the ultrasounds came back from the two other vets as suspensory desmitis, an injury. When the original vet was asked about the other two diagnosis, he said "that's what I saw too, but it was a Peruvian horse. I thought there could have been something else going on." The gelding two years later remains very sound and strong and has been wining gait classes in shows.

Case #2

Jenee DeMers' twelve year old mare was lame and one of the fetlocks was swollen. She wanted a vet to examine her. She took the mare to Washington State Veterinary School in Pulman, Washington. When she got there, a vet started examining her mare and was describing the injury and treatment. When a second vet appeared and asked her what breed of horse she had, she responded " Peruvian". At that point everything changed. She was told her mare had a confirmed case of DSLD and was given forms from DSLD Research, Inc. to fill out. Jenee, in disbelief, took her horse to the Peruvian farrier, coco Fernandaz, who trimmed her horse and put orthopedic shoes on her to stabilize the injury and gave it six months to heal. Nine months later Jenee was showing her horse.


Case #3
Tina Woodworth's eighteen year old Peruvian horse was diagnosed with DSLD by her vet, and she was told he may have to be "put down". Tina took her horse to another vet to get a second opinion, she had some blood work down and discovered his problem was a selenium deficiency. Tina started using a selenium supplement; her gelding is now fine.

The tragedy of these cases of misdiagnosis is significant, not onlyh for our breed of horse but for the individuals who euthanize their horses because they were incorrectly confirmed with DSLD.


Facts Considered

Here are some quotes from research papers and articles explaining injuries and DSLD. These veterinarians are all describing exactly the same symptoms, only Dr. Mero is describing an incurable disease in Peruvian horses and the other veterinarians and researchers are describing suspensory INJURIES in all equines. In the first example, Dr. Mero is doing both.


Example #1 Dr. Mero's Protocol for Diagnosis of DSLD

"These four steps: Palpation of the suspensory ligaments, observance of baseline lameness, fetlock flexion tests, and sonographic examinations of the suspensory ligament at mid-cannon and both branches. These four steps accurately provide the information needed to make a diagnosis of degenerative suspensory ligament desmitis (DSLD) in Peruvian Pasos Dr. Mero; Journal of Equine Veterinary Science.
1. Palpate the leg for pain
2. Observe the leg for lameness as he moves freely
3. Assess his soundness using a flexion test
4. Perform an ultrasound examination

"These steps aren't unique; they are all part of the normal, standard physical exam" Dr. Mero, from Equus Magazine: October 2005

"This protocol was not designed as a screening tool…At this point we do not have any good means to screen large numbers of horses for DSLD- the numbers of false positives and false negatives would be too high". Dr. Mero, DSLD Research Inc. website.


EXAMPLE #2 Dr. Mero Explains bilateral and quadrilateral involvement in DSLD

" one key component to diagnose ( in Peruvian Paso's) Is that unlike injury or other diseases, DSLD occurs bilaterally ( both fronts or both hinds) or quadrilaterally ( all four legs). It often starts in one limb only and appears to be one-legged ( often causing misdiagnosis at that point), but given time, always spreads." Subtle behavioral changes may be early indicators. Some horses resist having their legs touched or feet picked up. Many resist having their legs extended to the front or rear for trimming. Some just seem "off" or "cranky".


Bilateral Involvement in Suspensory Ligament Injury Sarah E. Powell, MA. Vet MB, MRCVS, Deidre M. Carson, BVSc MRCVS and Sidney W. Ricketts, LVO. BBc, BVSc.
" Clinical signs vary with the site of the injury and the severity of the damage. When the origin of the suspensory ligament is damaged (known as Proximal suspensory desmitis) the condition is often "bilateral" i.e. in both fore or both hind limbs. There is usually no heat or swelling but there may be some pain when the area just below the back of the carpus (knee) or hock is pressed firmly with the leg in a flexed position. In these horses the lameness may be subtle and " especially in the hind limb) often develops gradually and goes undiagnosed for some time"


EXAMPLE #3 Dr. Mero: Suspensory Ligament enlargement from her 2002 study on DSLD

"What is unique to Peruvians is the progressive enlargement of the suspensory ligament primarily involving both branches over time in more than one limb. There is a diffuse loss of echogenicity and poor fiber pattern images noted throughout the affected portions of the ligament."


UC DAVIS Ultrasound and Musuloskeletal Injuries in Horses

" The clinical signs of a tendon or ligament injury can be quite varied. Lameness can range from mild to severe and may be somewhat transient, sometimes lasting only a few days. Chronic injuries often result in persistent thickening of the tendon or ligament and an intermittent or persistent lameness".


Sarah E. Powell, MA, VetMB, MRCVS, Deidre M., Carson, BVSc, MRCVS, and Signey W. Ricketts, LVO, BAc,BVSc

"With injury to the branches, there is usually thickening of the affected region. Warmth and tenderness may o rmay not be present. If the ligament is ruptured, the fetlock will "sink" towards the ground, fully or partly, depending on the completeness of the rupture. Ligaments are made up of fibers that run along their length in a regular, well-organized manner. When the fiber are damaged some heal in an irregular, crisscross pattern rather than lengthways. Also, the repaired tissue is different in structure and mechanical properties than the original, healthy ligament tissue. Therefore the ligament will always be compromised in structure and function rendering it susceptible to re-injury."



Dr. Mero: The Cellular Changes with DSLD (Gaited Horse Magazine)
" Change first occur at the cellular level. In the first line of repair, cells called fibroblasts lay in a form of collagen known as TYPE III- a small, weak, not very pliable molecule. As damage inceases, they progressively build up to installing stronger, larger, more elastic TYPE I collagen. But for some unknown reason, these cells change in DSLD horses. They fail to lay in the stronger type of collagen. As the suspensories in DSLD horses become dominated by type III collagen, they weaken"
The Tendinosis Cycle: Cellular Changes with Tendinosis ( Tendinosis.Org)
Teninosis is a slow accumulation of little injuries that are not repaired properly and leave the tendon vulnerable to yet more injury. The tendinosis cycle begins when breakdown exceeds repair. Repetitive motion causes microinjuries that accumulate with time. Collagen breaks down and the tendon tries to repair itself, but the cells produce new collagen with an abnormal structure and composition.

The new collagen has an abnormally high Type III/Type I ratio. Experiments show that the excess Type III collagen at the expense of Type I collagen weakens the tendon, making it prone to further injur. Part of the problem is that the new collagen fibers are less organized into the normal parallel structure, making the tendon less able to withstand tensile stress along the direction of the tendon.


Cellular Changes: The pathogenesis of Tendinopathy. A molecular perspective

G. Riley, Oxford Journal of Equine Medicine

"Collagen Matrix changes in tendon pathology could be attributed to intrinsic factors, such as changes in cell activity with age, or extrinsic factors, such as 'overuse', repetitive strain and micro trauma injuries. In degenerative tendon there is an increased rate of collagen matrix remodeling, leading to a qualitatively different and mechanically less stable tendon, which is susceptible to damage. Thus tendon degeneration may result from a failure to regulate specific MP activities in response to repeated injury or mechanical strain."


How the Equine Superficial Digital flexor Tendon Responds to Physiologic Challenges and Physical Therapy, Yi-lo Lin and, A. Barnveld, Prof. Phd, Dvm Univeristy of Utrecht
"The scar tissue that is induced is of inferior quality compared to the original tissue due to alterations in biochemical composition and structural organization, compromising the functional restoration of pre-injured structure. This leads to high re-injury rates when athletic activity is resumed."

"The equine superficial digital flexor tendon and suspensory ligament can be considered as the most vulnerable structures of the entire equine body" Dr. Yi-lo Lin.
Most ligament and tendon injuries are accumulations of smaller injuries or micro-injuries that lead to a breakdown, and not one traumatic event. Dr. James Hamilton, DVM of South Pines Equine Associates in North Carolina, describes it this way, "damage (to tendons and ligaments) most often, is cumulative, starting with minor traumas that weaken tendon fibers and cause mild inflammation without lameness or detectable soreness." He likens the process to a rope with individual fibers breaking/ "eventually" he says, " you would reach a critical threshold of weakness." At that point the horse becomes lame swelling begins around the injury and the horse will then need a lot of care and a long recuperation.

Any injury will degenerate if it is not stabilized. Any injury in one leg may become bilateral, unless both legs are stabilized. In other words when one front leg is injured and wrapped, you must always wrap the other one so the horse doesn't overload the sound leg. The race horse, Barbaro, was put down because of complications in his left leg. His right leg was the one that was broken, but Barbaro's condition quickly became bilateral. As Pulitzer prize winning equine author, Jane Smiley, writes about equine ijuires, "(Horses) are engineered so close to the margins of what is physically possible that when one ting fails, it can cause the failure of the whole animal."

Injuries to suspensory ligaments can be hard to diagnose and lameness can come and go, but the injury is still there. Suspensory ligament injuries are also hard to heal. Many will take months, not weeks or days, and when they do heal they are often easier to re-injure, resulting gin a chronic, recurring problem. A second opinion and long recuperation periods are always good ideas. Because there is no test for DSLD and no study has ever been done that states the Peruvian horse is more prone to any disease or injury, finding out exactly what DSLD is, can be very confusing for horse owners and vets alike.



What's better than the successful rehabilitation of a tendon or ligament injury? The answer is: Preventing an injury from happening in the first place. Peruvian horses, with their tremendous brio and willingness to please make it even harder to detect injuries. While it's impossible to completely avoid injury in athletic horses, these precautions might help to minimize your horse's chance for injury. Tendon and ligament injuries take the longest to heal, and some never do, so prevention is the key.

1. Good horses are good horses in any breed. Learn the principles of conformation and breeding. What are good angles? What does a post legged horse look like? Why is a short back better than a long one?

As the veterinarians at Alamo Pintado say, "The simple answer to this problem is not to breed bad-legged horses to bad-legged horses, or to breed any horse with a severe inherited conformation fault. Once that becomes obvious, the problem goes away."

2. Learn to recognize the subtle signs of an injury before it becomes severe. Identify any abnormal heat or swelling in your horse's legs by carefully feeling his legs every day before you ride and taking note of any changes. You should also pay close attention to any lame steps or obvious changes in his behavior. If you think something feels wrong when you ride, call your vet. By doing so, you'll prevent a minor strain from becoming a catastrophic injury.

3. Proper, timely trimming is perhaps the most important thing you can do to safeguard the health of your horse's feet and legs. Not all farriers are created equal, so get recommendations from someone you trust. Many Peruvian horse's hooves grow forward and can become unbalanced quickly. Bad trims can cause micro-injuries to accumulate while your horse is standing in his stall or walking in a pasture by increasing pressure on suspensory ligaments. As soon as you suspect a problem, address it. Horses should never be sore after a trim; master farrier, Coco Fernandaz, trims horses the day before a show. He says, "They should be better after a trim, not worse."

4. Careful conditioning is critical. Regular long, slow, distance work-walking-helps keep tendons and ligaments tight and healthy. AND, even though you want your horse to look good, you are not his friend by feeding him too much. Excess weight stresses joints, tendons, and ligaments.

5. Work footing needs to be deep enough to lesson concussion, but not so deep that it strains tendons or ligaments. Avoid rocky or slippery surfaces and footing you can't see.

6. Always warm up your horse thoroughly before you ride. Plan to walk him a minimum of 10 to 15 minutes before you start to work.

7. Protect our horse's legs with polo wraps or sports medicine boots; they provide good support and protection when applied properly. Ask your vet about recommendations for your horse. He/she can also advise you on measures such as icing, and applying stable bandages after stressful workouts.

We can all agree that educating our members to these steps would be beneficial, but just listing them in a paper is not the answer. We need to be pro-active in educating our members. NAPHA needs to sponsor and support activities like the Peruvian Horse Congress held in Lompoc, California in 2006. At this Congress several successful breeders and experts in their equine specialties came together and shared their knowledge.

Prominent breeders, judges, veterinarians, and farriers, altogether in one places answering questions, demonstrating good and bad conformation with real horses, a farrier demonastrating a good trim and educating owners to the needs of Peruvian horses, trainers talking about conditioning and good equitation, showing us the proper way to wrap our horse's legs, veterinarians talking about injuries and showing members how to correctly palpate tendons and ligaments for soreness. This should be going on every year in a different part of the country with local veterinarians invited to attend.

We also need to have a positive educational presence on the internet. A place that promotes the same values that are demonstrated in these congresses and are displayed for the general horse owning public to reference. The breed very much needs a central website that is dedicated to just these issues and is promoted by NAPHA.

And finally, we need to stand up and support our horses, to other breeds, to other owners, and especially to the veterinary community that is misdiagnosing our horses.



We have a strong, wonderful horse that is getting some very bad publicity. We need to educate the veterinary community as well as the owners of these great horses and not let a small group of negative people be the only ting the public hears. Alamo Pintado is a world renown veterinary clinic that sees more Peruvian Horses than probably any clinic in the world, and after thirty years, following is what they have to say about Peruvian horse:

" In our experience, the Peruvian Paso, as a breed, is a very tough, durable and sound breed of horse when compared to all the other breeds of horses we see at Alamo Pintado Equine Medical Clinic." Doug Herthel DVM, Mark Rick DVM, Greg Parks DVM, Ed Hamer,DVM. Judy Carter DVM.



This is the control horses chart used in the Dr. Halper study.


Below is the list of DSLD affected Peruvian Paso horses. The Proteoglycan levels are very similar to those of the control horses.

These charts are the summary of Dr. Halpers study.

According to Dr. Halper, the accumulation of unidentified proteoglycans throughout the body is what makes DSLD a systemic disease and the accumulation of this proteoglycans in the nuchal ligament is where a biopsy can be taken for a DSLD test. This test was described as a breakthrough in a national press release.

However, by simply looking at Dr. Halper's own charts we can see that the unaffected Peruvian control horse has this accumulation in as many places as the affected horses and five of seven of the unaffected control horses would test positive with a nuchal ligament biopsy. Also all of the young horses had one or both of their parents broken down, which could only mean that these breeders were breeding broken down horses to each other and producing broken down offspring…a not very surprising result. As the vets at Alamo Pintada say "don't breed bad legged horses, to bad legged horses and the problem goes away."

Also included is a e-mail from someone who had a necropsy done by Dr. Halper and was told her mare had extensive DSLD but had NO accumulation in the nuchal ligament or any of the other organs.


Attachment #2 Veterinarian database Search

This is the actual data from the veterinary schools recording INJURY not DSLD.

Here is an example of how faulty research creates misinformation and how it can hurt our Peruvian horse breed for years.

This is a data base search of suspensory INJURIES; suspensory ligament desmitis, suspensory ligament sprain and suspensory ligament rupture, in veterinary colleges in North America. These are injuries, they are not codes for disease, and there is nothing in these statistics that normalizes them to a population, only to the horses injured. However, by the time we have finished reading this survey, these horses have been diagnosed with suspensory ligament disease and Peruvian horses have the second highest percentage of this disease, just below Standardbreds.

What do these statistics really show? That there were only 24 suspensory injuries reported to these veterinary colleges for Peruvian Paso horses, over a ten year period…and that's all.

This research was done in 2002 and was taken from the DSLD/ESAD information web page in 2007.

This misinformation has been referenced many times, including the PPHRNA RAM meeting in 2003 and , most recently, in an article on gaited horses in Horseman News (October 2005). It is part of the Golden Gaited web site and is used in describing Peruvian Horses.


Veterinarian Database Search

Below are results of a query of the Veterinary Medical Data Program, done by Alice J. Wolf. DVM., DACVIM, DABVP. Information is compiled from veterinary colleges in North America. The data below represents a survey of 10 years of data from 1987 -1997. the percentages come from a comparison of all the horses of each breed that were brought to these schools for any problem to the number that were subsequently diagnosed as having suspensory ligament disease. That normalizes the percentages to the number of horses in the population.

The query specifically searched for the following diagnoses: Suspensory ligament Desmitis, Suspensory Ligament Rupture, Suspsensory Ligament Sprain, and Suspensory ligament Laxity. At the time of this query, there were the only codes for suspensory ligament disease in the veterinary computer databae Breeds are listed by frequency of incidence for these problems. Breeds where no individual was diagnosed with suspensory ligament disease are not listed. Breeds with less than 10 individuals seen per year are also not listed as the number is statistically insignificant.

Vet database
Return to the Equine Suspensory Apparatus Dysfunction home page.


This report went on for several more pages providing copies of misleading letters posted to Dr. Mero's web site and other distorted articles giving misleading information on various web pages of so called "experts" in the horse world. These erroneous reports, documents, letters and internet comments are all based upon the distortion of documentation created from the original injury data collected over a ten-year period from all the veterinary hospitals in the United States. Data is only as good as the compilers integrity. To leave out bits or to change factual evidence is to give a misleading impression of the situation.

While the distortion continues so does the request from many of those publishing this data out of context for contributions to fund further research for themselves.





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