Equinevet February 2015

The Modern

Equine Vet www.modernequinevet.com

Field tips for finding

lameness

Rope tricks: Managing dummy foal syndrome Saddle fit: At rest and in motion

Vol 5 Issue 2 2015

Table of Contents

Cover story:

6 Field tips for

finding lameness Cover Photo: bob@boblangrish.co.uk

sports medicine

Saddle fit: At rest and in motion.........................................................................................8 Neonatal Care

Rope trick helps reverse dummy foal syndrome........................................................12 cardiology

Clydesdale's big heart skips more than a beat............................................................16 Technician Update

Do zebras need hoof trims?............................................................................................18 News

New CT scanner tailor made for the horse.....................................................3 Why do zebras have stripes?..........................................................................11 Best foot forward with new hoof book.....................................................15 Video: Dummy fold syndrome technique....................................................14 advertisers Shank's Veterinary Equipment................................. 3 Avalon Medical............................................................. 5

CEVA Animal Health.................................................... 7 AAEVT............................................................................17

The Modern

Equine Vet Sales: Robin Geller • newbucks99@yahoo.com Editor: Marie Rosenthal • mrosenthal@percybo.com Art Director: Jennifer Barlow • jbarlow@percybo.com contributing writerS: Paul Basillo • Kathleen Ogle COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers percybo media  publishing

2

Issue 2/2015 | ModernEquineVet.com

LEGAL DISCLAIMER: The content in this digital issue is for general informational purposes only. PercyBo Publishing Media LLC makes no representations or warranties of any kind about the completeness, accuracy, timeliness, reliability or suitability of any of the information, including content or advertisements, contained in any of its digital content and expressly disclaims liability of any errors or omissions that may be presented within its content. PercyBo Publishing Media LLC reserves the right to alter or correct any content without any obligations. Furthermore, PercyBo disclaims any and all liability for any direct, indirect, or other damages arising from the use or misuse of the information presented in its digital content. The views expressed in its digital content are those of sources and authors and do not necessarily reflect the opinion or policy of PercyBo. The content is for veterinary professionals. ALL RIGHTS RESERVED. Reproduction in whole or in part without permission is prohibited.

News

New CT scanner tailor made for the horse Epica Medical Innovations recently released Pegaso, a new computed tomography (CT) scanner specifically designed for equine medicine.

The multi-modality Pegaso unit features a resolution that is 1,481 times higher than standard CT. The vastly superior image quality will help practitioners to provide more accurate diagnoses and treatment plans.

And they can show these 3D views of the horse’s injuries or problems to owners so they can make better decisions regarding their animals’ care.

“The Pegaso provides unmatched CT image quality for both soft and hard tissues. It will change our imaging paradigm for the horse,” said Chris Kawcak DVM, PhD, DACVS, DACVSMR, professor, Equine Orthopedic Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University.

The new diagnostic, interventional and intraoperative scanner will fulfill the unmet imaging needs of equine veterinarians, who have struggled with getting good equine CT images because of the horse’s size. The average thoroughbred weighs more than 1 ton and stands between 62 and 68 inches tall. With The 1.2 meter diameter of the variable geometry, tilting gantry, equine veterinarians can perform a CT scan of a standing horse’s head and neck up to the C7 vertebrae.

Pegaso can scan any anatomy, including distal limbs, of an anesthetized horse and provides high quality images.

The fully robotic, high-definition CT scanner also includes large field, high resolution flyoroscopy and digital radiography. Because it is mobile, it can easily be moved around the practice.

Pegaso provides scans that are 1,481 times higher resolution than other scans and are built to accommodate a horse's size.

“When we designed the Pegaso, our sole focus was to design an imaging device that solved the frustrations experienced by equine veterinarians making due with machines that were made for humans and trying to squeeze horses into them. Not only were we able to design such a device, we reduced radiation by 60-90% less than standard CT making Pegaso significantly safer for horses and the clinicians who use it.

"We believe this will change the face of veterinary medicine,” said Greg Stoutenburgh, president of Epica Medical Innovations. The drastic reduction of radiation enables the practitioner to use the device safely interventionally, or intra-operatively; which opens up a world of new opportunities equine veterinarians can diagnose and treat horses, ultimately improving prognoses and outcomes.

For a product demonstration, video’ and more information: epicamed.com/products/pegaso. MeV

Lifting Large Animals Since 1957

www.shanksvet.com • info@shanksvet.com ModernEquineVet.com | Issue 2/2015

3

Hoof tester channel lock.

Field tips for finding lameness pathology B y

4

P a u l

Issue 2 /2015 | ModernEquineVet.com

B a s i l i o

During the past decade,

magnetic resonance imaging (MRI) has become the gold standard for identifying much of the pathology associated with lameness of the equine foot, according to Tracy A. Turner, DVM, MS, DACVS, DACVSMR, a veterinarian with Anoka Equine Veterinary Services in Elk River, Minn.

However, sometimes MRI is almost “too good� at detecting pathology, he added, because it can reveal more than one problem area, and a veterinarian still has

Photo Courtesy of Dr. Turner

Low tech options:

cover story

to depend on his or her diagnostic acumen to determine which lesions on the MRI are actually causing the lameness pain.

“How often do you get an MRI report [for a lame horse] and there’s a list of pathologies?” He asked here at the 60th Annual AAEP Convention in Salt Lake City. “At that point you start tearing out your hair,” he joked.

This scenario highlights the need for a thorough clinical examination—and the use of manipulative tests in particular—to determine the significance of lesions found in the hoof and guide treatment options.

Hoof Tester

“Traditionally, the application of hoof testers has been the biggest manipulative test that we’ve done,” Dr. Turner said. “But we have to

look at how the hoof fits with the rest of the leg, and how stress affects different structures and pain inside the foot. There are other manipulative tests that we can do.”

Distal Limb Flexion

For distal limb flexion, the horse’s leg is held in flexion for a certain amount of time. A test is considered positive if lameness is exacerbated afterward. Dr. Turner noted that there may be more than one way to flex a horse’s leg, but he is not convinced that there is a significant difference.

“A colleague of mine swears that if you have the foot placed underneath the body then that will test more for the fetlock, and if you place the limb forward then that will test more for the hoof,” he said. “I haven’t seen much of a difference. However, I prefer to

pull the leg forward each time for consistency of pressure. I will hold the end of the toe, pull the leg forward, and the horse does all the flexion. I’ll hold the horse in that position for 30 seconds.”

Some studies have shown that distal limb flexion will exacerbate foot lameness in 90% of affected horses. “However, this test has a low specificity,” Dr. Turner said.

“In my experience, a strong positive test suggests joint issues, such as osteoarthritis or synovitis.”

Wedge Tests

If a flexion test exacerbates pain inside the foot, Dr. Turner will place the horse on a wedge or a block to further identify the source of the pain.

“By placing it underneath a part of the hoof, the wedge is going to apply pressure to the wall,”

Wound care, redefined.

• Rapid, scar-free healing • Angiogenic and osteogenic properties

• Anti-microbial • Easy application

RediHeal Wound Care products promote rapid, scarfree healing while providing continuous anti-microbial protection. Trauma injuries, lacerations, and abscesses are just a few of the applications where RediHeal has found success when other wound treatments have failed.

Don’t make treating your next wound harder than it has to be. Get all the exciting details at www.rediheal.com, or click on this ad for an amazing equine case study.

www.AvalonMed.com 888.289.1890

ModernEquineVet.com | Issue 2/2015

5

Photo Courtesy of Dr. Turner

cover story

Clockwise: toe wedge; frog wedge test; wall wedge

Dr. Turner explained. “That is going to compress one side and stretch the other. I find that this test is going to be much more specific for collateral ligament pain.”

A toe wedge test will put pressure on the deep flexor tendon, but it also includes compression of the distal aspect of the navicular bone against the deep flexor tendon.

6

Issue 2/2015 | ModernEquineVet.com

This is an area where remodeling is known to occur in the navicular bone.

“When I see a positive toe wedge test, the response suggests deep flexor pain,” Dr. Turner said.

“You could argue that it is an abscess, but you’re really stretching the back part of this leg.”

Following a positive toe wedge test, Dr. Turner will perform ultrasonography of the deep digital flexor tendon, including the pastern and across the frog.

A frog wedge test has been shown to have an 85% predictive value for navicular pain, Dr. Turner said. The test compresses the hoof through the frog and the digital cushion and puts pressure on the navicular bursa.

“A positive frog wedge test almost invariably leads me to do a bursagram on the horse,” he said.

“It’s going to give me more information about the pathology.”

A positive test will also pinpoint the need for deep compression with hoof testers and therapy with intra-articular injections, according to Dr. Turner.

Decision tree

“It is imperative to rely on a thorough clinical examination to

help determine the importance of each lesion,” Dr. Turner said. “This is how you can make a hierarchy of the lesions.”

If the wedge tests are negative, then the focus shifts to intra-articular or peripheral analgesia to look for joint pain, additional imaging and possible need for a farrier. A positive test leads to ultrasonography of the collateral ligaments.

If the ultrasound is positive, the horse will need rest because it has a serious injury.

“A positive frog wedge test means deep pain inside the foot,” Dr. Turner explained. “It also tells me the frog pressure tolerance the horse has, and this specifically can have implications toward shoeing."

Often, the frog wedge test can lead a veterinarian to perform analgesic injection of the navicular bursa or peripheral analgesia for a specific area, he said.

"If I have a positive frog wedge test, I am going to want to do a toe wedge test, which will lead me to look at increased pressure between the deep flexor tendon and the navicular bone or deep flexor pain. That is going to lead me to perform peripheral analgesia,” Dr. MeV Turner explained.

NOW AVAILABLE IN THE U.S. Over 250,000 doses administered worldwide in the last 12 years.

Now FDA approved for use in the U.S. and available from your veterinary distributor, Tildren® (tiludronate disodium) controls clinical signs associated with navicular syndrome in horses. Tildren works at the areas of active bone resorption, restoring balance to the process of bone remodeling.

Contact your local distributor or Ceva Animal Health representative for more information.

Do not use in horses with impaired renal function or with a history of renal disease. NSAIDs should not be used concurrently with TILDREN. Concurrent use of NSAIDs with TILDREN may increase the risk of renal toxicity and acute renal failure. Horses should be observed closely for 4 hours post-infusion for the development of clinical signs consistent with colic or other adverse reactions. Caution should be used when administering TILDREN to horses with conditions affecting mineral or electrolyte homeostasis (e.g. HYPP, hypocalcemia) and conditions which may be exacerbated by hypocalcemia (e.g. cardiac disease). The safe use of TILDREN has not been evaluated in horses less than 4 years of age, in pregnant or lactating mares, or in breeding horses.

©2015 Ceva Animal Health, LLC. Lenexa, KS 66215

TILDREN is a registered trademark of Ceva Santé Animale, France.

TILDREN.COM/US ModernEquineVet.com | Issue 2/2015

7

Bisphosphonate drug for intravenous infusion.

For use in horses only.

Brief Summary: See package insert for full prescribing information.

Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian.

Description TILDREN is a sterile powder. Each vial of TILDREN contains 500 mg of tiludronic acid (as tiludronate disodium) and 250 mg mannitol USP (excipient).

Indication TILDREN is indicated for the control of clinical signs associated with navicular syndrome in horses.

Contraindications Do not use in horses with known hypersensitivity to tiludronate disodium or to mannitol. Do not use in horses with impaired renal function or with a history of renal disease. Bisphosphonates are excreted by the kidney; therefore, conditions causing renal impairment may increase plasma bisphosphonate concentrations resulting in an increased risk for adverse reactions.

Warnings Do not use in horses intended for human consumption.

NSAIDs should not be used concurrently with TILDREN. Concurrent use of NSAIDs with TILDREN may increase the risk of renal toxicity and acute renal failure.

Appropriate wash-out periods should be observed between NSAID and TILDREN administration, and BUN and creatinine should be monitored. If treatment for discomfort is required after TILDREN administration, a non-NSAID treatment should be used.

Human Warnings Not for human use. Keep this and all drugs out of the reach of children. Consult a physician in case of accidental human exposure.

Precautions Approximately 30-45% of horses administered TILDREN will demonstrate transient signs consistent with abdominal pain (colic). Hand-walking the horse may improve or resolve the colic signs in many cases. If a horse requires medical therapy, non-NSAID treatments should be administered due to the risk for renal toxicity. Avoid NSAID use.

TILDREN should be administered slowly and evenly over 90 minutes to minimize the risk of adverse reactions.

Horses should be well hydrated prior to administration of TILDREN due to the potential nephrotoxic effects of TILDREN. Concurrent administration of other potentially nephrotoxic drugs should be approached with caution, and if administered, renal function should be monitored.

Caution should be used when administering TILDREN to horses with conditions affecting mineral or electrolyte homeostasis (e.g. hyperkalemic periodic paralysis (HYPP), hypocalcemia, etc.) and conditions which may be exacerbated by hypocalcemia (e.g. cardiac disease).

TILDREN should be used with caution in horses receiving concurrent administration of other drugs that may reduce serum calcium (such as tetracyclines) or whose toxicity may exacerbate a reduction in serum calcium (such as aminoglycosides).

Horses with HYPP (heterozygous or homozygous) may be at an increased risk for adverse reactions, including colic signs, hyperkalemic episodes, and death.

The safe use of TILDREN has not been evaluated in horses less than 4 years of age. The effect of bisphosphonates on the skeleton of growing horses has not been studied; however, bisphosphonates inhibit osteoclast activity which impacts bone turnover and may affect bone growth.

Bisphosphonates should not be used in pregnant or lactating mares, or mares intended for breeding. The safe use of TILDREN has not been evaluated in pregnant or lactating mares, or in breeding horses.

Increased bone fragility has been observed in laboratory animals treated with bisphosphonates at high doses or for long periods of time. Bisphosphonates inhibit bone resorption and decrease bone turnover which may lead to an inability to repair microdamage within the bone. In humans, atypical femur fractures have been reported in patients on long term bisphosphonate therapy; however, a causal relationship has not been established.

Adverse Reactions: The most common adverse reactions reported in the field efficacy and safety studies were clinical signs consistent with abdominal discomfort or colic.

Other reported signs were frequent urination, muscle fasciculations, polyuria with or without polydipsia, and inappetance/anorexia.

For technical assistance or to report suspected adverse reactions, call 1-800-999-0297.

Marketed by: Ceva Animal Health, LLC Lenexa, KS 66215 TildrenÂŽ is a registered trademark of Ceva SantĂŠ Animale, France NADA 141-420, approved by the FDA

8

Issue 2/2015 | ModernEquineVet.com

sports medicine

Saddle Fit:

At Rest and In Motion

Shutterstock/ Fotokostic

Current recommendations

for proper saddle fit are largely empirical. It is understood that the saddle needs to fit the rider and the horse at rest and in motion to avoid pain and impairment of performance, but the science behind the fitting often is neglected.

Sue Dyson, MA, VetMB, PhD, DEO, FRCVS, of the Centre for Equine Studies at the Animal Health Trust in New Market, UK, and her colleagues recently investigated the factors involved in exercise-induced changes in muscle dimensions and the effects those changes can have on a horse’s performance and overall well being.

“In humans, exercise induces an acute change in cross-sectional areas of muscle that vary depending on the exercise type and intensity of the muscles used, and whether blood supply is limited,” Dr. Dyson said here at the 60th Annual AAEP Convention in Salt Lake City.

“However, we have little knowledge of the changes in muscle dimensions associated with work in horses.”

B y

Dr. Dyson’s study investigated changes in back dimension in horses of various ages and work.

The study was designed to quantify changes in back dimension that occur subsequent to ridden exercise, and to determine the influence of work quality, saddle fit and rider skill level.

“We hypothesized that the changes immediately after exercise would be quantifiable,” she said.

“Horses working on the bit would have larger changes than horses not working on the bit, and an ill-fitting saddle before work would diminish any transient increase in back dimensions after work.”

The prospective study involved 63 horses who were ridden by their usual rider in normal tack. Back dimensions were measured before and immediately after exercise at the 18th, 13th and 8th thoracic vertebrae (T18, T13, and T8), as well as a point one-third of the distance from the point of the elbow to the point of the shoulder. A flexible curve ruler was contoured around the horse’s back and then the out-

P a u l

line was traced on graph paper. The width of the horse’s back was measured at 3 cm and 15 cm ventral to the dorsal midline, and ratios for these distances were determined.

The fit of the saddle and numina were assessed objectively. All horses were ridden for 30 minutes on the flat by their normal rider. Video footage was obtained near the end of the session in both straight lines and circles.

Results

“At all measurement sites, we detected differences in back dimensions when comparing the horse before and after exercise,” Dr. Dyson explained. “There were greater changes at 15 cm ventral to the dorsal midline at the shoulder, T8 and T13. The biggest changes in dimension were seen at T13 and T18, especially at 3 cm ventral to the midline at T18, which are the areas underneath the middle and back of the saddle.”

Sound horses had greater mean changes in back width 15 cm ventral to the midline at T8 and 3 cm

B a s i l i o

ModernEquineVet.com | Issue 2/2015

9

Photo Courtesy of Dr. Sue Dyson

sports medicine

The back of a horse ridden with the fluffy numnah

ventral to the midline at T13 when compared with lame horses. Interestingly, 22 horses that were thought to be sound by the owners had gait abnormalities.

Twenty-eight riders were evaluated. Four were categorized as hav-

ing a poor skill level, six were categorized as moderate, and 18 were categorized as good. The mean changes in back dimensions at each site were greater in horses ridden by good riders compared with moderate and poorly skilled riders.

Instant Gratification One horse involved in the study had padding under the saddle, a gel pad and a very thick, fluffy numnah. After exercise, dry spots were noted under the saddle, which is an indication of an improper fit.

“This horse worked in a very uncomfortable manner with its head in front of the vertical (i.e., ‘above the bit’),” Dr. Dyson said. “There was little change in back dimension in this horse.”

When the pads were removed and the exercise was repeated, the horse showed a markedly improved increase in back dimensions at all measured sites.

“The horse worked phenomenally better in quality after the pads were removed,” she explained.

10

Issue 1/2015 | ModernEquineVet.com

“The mean changes at T8 were actually greatest for the moderately skilled riders, but all of those horses had a well fitting saddle,” Dr. Dyson noted.

The saddle was balanced in 39 horses and fitted with even contact without bridging in 35 horses. In 24 horses, the saddle was unbalanced. Saddles tipped backward in 9 horses and forward in 15. Saddles consistently slipped to one side in 4 horses, and oscillated from left to right in 5 horses. In 2 horses, the saddle consistently slipped forward.

“We can see that the changes in the back ratios are considerably greater in horses with fitting saddles compared with ill-fitting

news notes

saddles,” Dr. Dyson said. “In fact, some horses with ill-fitting saddles had negative changes after exercise.”

Age was associated negatively with ratio changes. Older horses showed less change in back dimension than younger horses did. In addition, the more convex the shape of the back before exercise, the less change in ratio was noted following exercise.

“This demonstrates there are quantifiable changes in back dimensions with exercise, and horses working correctly on the bit in a well-fitted saddle are likely to have greater changes than those in illfitting saddles who are ridden incorrectly,” she said. “Failure to work correctly will result in lack of longterm muscle development, and the horses may have poor muscle tone.”

Saddles that tip forward or backward are also likely to result in a focal increase in pressure. Cumulative pressure over days and months may result in back pain and altered movement of the back, which can contribute to failure of the development of back muscles or the induction of muscle atrophy.

“A saddle that fits a horse at rest may not fit the horse when it is in a correct posture and working properly with increased tightness of the panels, especially in the region of the stirrup bars,” Dr. Dyson said.

“This has potentially important implications for movement of the back, the scapulae and the thoracic girdle. It seems likely that back muscle development is in part related to these transient exercise-induced increases in back dimensions.”

The high proportion of incorrectly fitted saddles in the study may be an indication that better owner education about saddle fit is needed. “Saddle fit should be checked before and after exercise,” she said. “Lack of clearance of the spinous processes by the saddle or by an overtight numnah may com­ MeV promise back movement.”

Why do zebras have stripes?

One of nature's fascinating questions is how zebras got their stripes.

A team of life scientists led by UCLA's Brenda Larison, PhD, has found at least part of the answer: The amount and intensity of striping can be best predicted by the temperature of the zebra's environment.

In the January cover story of the Royal Society's online journal, Open Science, the researchers make the case that the association between striping and temperature likely points to multiple benefits, including controlling zebras' body temperature and protecting them from diseases carried by biting flies.

"While past studies have typically focused their search for single mechanisms, we illustrate in this study how the cause of this extraordinary phenomenon is actually likely much more complex than previously appreciated, with temperature playing an important role," said Thomas B. Smith, PhD, professor of ecology and evolutionary biology in the UCLA College and senior author of the research.

Dr. Larison, a researcher in UCLA's department of ecology and evolutionary biology and the study's lead researcher, and her colleagues examined the plains zebra, which is the most common of three zebra species and has a wide variety of stripe patterns. On zebras in warmer climes, the stripes are bold and cover the entire body. On others—particularly those in regions with colder winters, such as South Africa and Namibia—the stripes are fewer and are lighter and narrower. In some cases, the legs or other body parts have virtually no striping.

Zebras evolved from horses more than 2 million years ago, biologists have found.

Scientists have previously hypothesized that zebras' stripes evolved for one, or a combination of, four main reasons: 1. Confusing predators, 2. Protecting against disease-carrying insects, 3. Controlling body temperature and A zebra with a foal in Tanzania's Tarangire National Park.

4. Social cohesion.

Credit: Brenda Larison/UCLA And while numerous previous studies of the phenomenon focused on a single hypothesis, Dr. Larison’s team were the first to fully test a large set of hypotheses against one another.

Analyzing zebras at 16 locations in Africa and considering more than two dozen environmental factors, the researchers found that temperature was the strongest predictor of zebras' striping. The finding provides the first evidence that thermoregulation is the main reason for the stripes and the patterns they form.

Separate research by Daniel Rubenstein, PhD, a Princeton University professor of ecology and evolutionary biology and a co-author of the Open Science paper, and Princeton undergraduate Damaris Iriondo strongly suggests that boldly striped zebras have external body temperatures about 5° F cooler than other animals of the same size, such as antelopes, which do not have stripes but live in the same areas. The Rubenstein study is not yet published, but it is cited in the Open Science paper.

Dr. Larison has studied many zebras during her field work throughout Africa, including Kenya, South Africa, Tanzania, Uganda and Zimbabwe. Using the fact that their stripes are as unique as fingerprints, she is able to distinguish one zebra from another.

The research was supported by the National Geographic Society Committee for Research and Exploration.

Dr. Larison and her research team have also collected zebra tissue samples and have used cutting-edge technology to sequence zebra DNA to try to identify which genes code for striping. The team is continuing to study the benefits stripes provide.

MeV

For more information: Larison B, Harrigan RJ, Thomassen HA, et al. How the zebra got its stripes: a problem with too many solutions.

Royal Society Open Science, 2015; 2 (1): 140452 DOI:10.1098/rsos.140452

ModernEquineVet.com | Issue 2/2015

11

neonatal care

Rope ‘trick’ helps reverse

dummy foal syndrome Veterinarians might be able to reduce maladjustment symptoms in foals by using several loops of a soft rope to gently squeeze the foal’s upper torso and mimic the pressure experienced in the birth canal.

Neonatal maladjustment or dummy foal syndrome has puzzled horse owners and veterinarians for a century.

Foals affected by the disorder seem detached, fail to recognize their mothers and have no interest in nursing. New research from the University of California at Davis suggest that abnormal levels of naturally occurring neurosteroids may be the cause, and a low-tech treatment called the Madigan Foal Squeeze Procedure may help.

Now the veterinarians have teamed up with their colleagues in human medicine to investigate possible connections to child-

hood autism, because some human infants also have abnormal levels of neurosteroids.

“The behavioral abnormalities in these foals seem to resemble some of the symptoms in children with autism,” said John Madigan, DVM, MS, DACVIM, DACAW, professor of veterinary medicine at University of California, Davis.

The maladjustment syndrome in foals also caught the attention of Isaac Pessah, MS, PhD, professor of molecular biosciences at the UC Davis and a faculty member of the UC Davis MIND institute, who investigates environmental factors that may play a role in the development of autistic spectrum

UC Davis School of Veterinary Medicine professor and researcher John Madigan squeezes a maladjusted foal at Victory Rose Thoroughbreds in Vacaville, Calif. on Jan. 21, 2015. The squeezing simulates the foal's trip through the birth canal. Madigan's research has found the squeezing to help the foal recover from Neonatal Maladjustment Syndrome, sometimes within hours. Photo Courtesy of Joe Proudman / UC Davis

12

Issue 1/2015 | ModernEquineVet.com

disorders in children.

“There are thousands of potential causes for autism, but the one thing that all autistic children have in common is that they are detached,” Dr. Pessah said Drs. Madigan and Pessah and other researchers in veterinary and human medicine recently formed a joint research group and secured funding to investigate links between the two conditions.

Photo Courtesy of Joe Proudman / UC Davis

UC Davis School of Veterinary Medicine professor and researcher John Madigan, inspects a maladjusted foal at Victory Rose Thoroughbreds in Vacaville, Calif. on Jan. 21, 2015.

Maladjusted foal syndrome

In newborn foals, neonatal maladjustment syndrome or dummy foal syndrome, occurs in 3% to 5% of live births. With around-the-clock bottle or tube feeding plus intensive care in a veterinary clinic for up to 10 days, 80% of the foals recover. But for horse owners, that level of care is grueling and costly.

For years, the syndrome has been attributed to hypoxia during the birthing process. Dr. Madigan and UC Davis veterinary neurologist Monica Aleman, PhD,

MVZ, DACVIM, began sleuthing around for other potential causes, however, noting that hypoxia usually causes serious, permanent damage, while most foals with the maladjustment syndrome survive with no lingering health problems.

One of their prime suspects was a group of naturally occurring neurosteroids, which are

key to sustaining pregnancies in horses, especially in keeping the foal “quiet” before birth.

Foals remain quiet in the womb

“Foals don’t gallop in utero,” Dr. Madigan is fond of saying, pointing out the dangers to the mare if a four-legged, hoofed fetus were to suddenly become active in the womb. The prena-

ModernEquineVet.com | Issue 2/2015

13

neonatal care

tal calm is made possible, he explains, by neurosteroids that act as sedatives for the unborn foal.

However, immediately after birth, the infant horse must make an equally important transition to consciousness. In nature, an equine neonate would be easy prey for many natural enemies, so the foal must be ready to run just a few hours after it is born.

In short, somewhere between the time a foal enters the birth canal and the moment it emerges from the womb, a biochemical “on switch” must be flicked that

ed by the fact that the maladjusted foal syndrome appears more frequently in horses that were delivered by cesarean section or experienced unusually rapid births. Perhaps those foals do not experience significant physical pressure to trigger the change in neurosteroids, Dr. Madigan said.

Furthermore, the research team has found for the first time that sedative neurosteroids persist, and their levels often rise, in the bloodstream of foals born with symptoms of the maladjustment syndrome. These neuros-

The veterinary researchers have found that they can reduce maladjustment symptoms in foals by using several loops of a soft rope to gently squeeze the foal’s upper torso and mimic the pressure normally experienced in the birth canal (see video). When pressure is applied with the rope, the foal lies down and appears to be asleep.

After 20 minutes—about the same time a foal would spend in the birth canal—the rope is loosened and the squeeze pressure released. In initial cases, the foals have responded well to the procedure and recovered, some rising to their feet within minutes and then bounding over to join the mare and nurse.

The researchers suspect that the pressure triggers biochemical changes in the CNS that are critical for transitioning the foal from a sleeplike state in the womb to wakefulness at birth.

Dr. Madigan cautions that, in spite of the strong observational effects, a larger, controlled clinical trial of national and international scope is now needed to reproduce those observed results and provide a better understanding of the mechanisms at work in the foals.

enables the foal to recognize the mare, nurse and become mobile.

Drs. Madigan and Aleman suspect that the physical pressure of the birthing process may be that important signal.

“We believe that the pressure of the birth canal during the second stage of labor, which is supposed to last 20 to 40 minutes, is an important signal that tells the foal to quit producing the sedative neurosteroids and ‘wake up,’” Dr. Madigan said.

teroids are known to be able to cross the blood-brain barrier and impact the central nervous system (CNS), acting on the same receptor as do sedatives and anesthetics.

The researchers also have demonstrated that maladjustment symptoms can be brought on temporarily in normal, healthy foals by administering short infusions of a neurosteroid called allopregnanolone. When the neurosteroid levels drop, the foals return to their normal state.

Foal behaviors resemble autism

Neurosteroids persist in the bloodstream

The theory, he said, is support-

14

Issue 1/2015 | ModernEquineVet.com

Foals ‘wake up’ with gentle harness pressure

The early findings have compelling implications for the health of newborn foals and have caused the researchers to also explore possible links to autism, which includes a group of complex braindevelopment disorders. While the symptoms vary, these disorders are generally marked by difficulties with social interactions, verbal and nonverbal communication, and repetitive behaviors.

“The concept that a disruption in the transition of fetal consciousness may be related to children with autism is intriguing,” said Dr. Pessah, noting that the behaviors

seen in the maladjusted foal syndrome truly are reminiscent of those in some autistic children.

He noted that some children with autism do outgrow autistic behaviors by the time they reach 13 years. Could this be a parallel to the recovery of the foals with the maladjustment syndrome?

Investigating possible links

A new group called the Comparative Neurology Research Group, consisting of veterinarians, physicians, epidemiologists and basic-science researchers, has formed to pursue further studies in this area. Dr. Madigan is working with researchers at the Stanford School of Medicine, exploring the mechanisms of postbirth transitions of consciousness related to neonatal care of infants.

Using data from the foal research, Drs. Pessah and Madigan are working with environmental epidemiologist Irva

Neonatal maladjustment syndrome occurs in 3% to 5% of live births. With around-the-clock bottle or tube feeding plus intensive care in a veterinary clinic for up to 10 days, 80% of the foals recover.

Hertz-Picciotto, PhD, MPH, at the UC Davis MIND Institute to investigate neurosteroids in children with varying degrees of autism, ranging from some developmental delay to full-spectrum autism.

The researchers are exploring whether abnormal regulation of neurosteroids during the period around childbirth could be one of many factors that might contribute to autistic spectrum disorders and related neurodevelopmental disorders. A recent study has reported elevated levels of neurosteroids in children with autistic spectrum disorder.

Dr. Pessah and colleagues will be looking to see whether there are alterations in blood levels of certain neurosteroids that may serve as a marker for the disorder. They caution, however, that the relationship right now is just a theory that remains to be validated or disproven.

MeV

Put best foot forward with new hoof care book Keeping horses comfortable and sound can be a complicated and often stressful process not only for the owner, but also for hoof care professionals.

Author Monique Craig, a hoof researcher and farrier, started her learning journey out of personal frustration with these same issues. Her goal was initially just to find solutions for her own horses. Eventually, her 20+ years of hoof research yielded results applicable to every horse.

A Modern Look At … THE HOOF, published by Outskirts Press is a new look at the hoof, focusing on a detailed look at its morphology and function, and discussing implications for how the hoof should be trimmed and cared for. Topics addressed include: • An introduction to hoof anatomy and structure, bones, hoof capsule, sole shape, pedal bone shape, weight bearing, false sole, the exfoliation cycle, toe callus and bevel, weather and soil mechanics, hoof packing, thrush, break over, tendon mechanics, and more.

• Measuring the hoof, including material on the natural asymmetry of the hoof capsule and bones of the lower leg of the horse. The ramifications of

these asymmetries have been rarely discussed in any other equine literature.

• Assessing the hoof, topic materials include annotated color images illustrating what constitutes a “normal” hoof, painstakingly collected by the author over 20 years of hoof trimming.

• The Epona Trim, which is her approach to trimming and assessing the hoof, addressing the natural asymmetry of the hoof and leg, as well as relating the trim to the bony column of the leg.

• Shoeing, including discussion of shoe placement and attachment (gluing, nailing or casting).

Ms. Craig, founder of EponaTech and the EponaInstitute, and inventor of the EponaShoe polyurethane shoe, includes an in-depth discussion of 16 case studies drawn from real-world application of her shoeing approach.

MeV For more information, visit www.EponaBook.com.

ModernEquineVet.com | Issue 2/2015

15

cardiology

Clydesdale's

Big Heart Skips More Than a Beat Leading a team of majestic Clydesdales is Wind-

sor, a special member of the eight-horse team that pulls a historic wagon for the Hallamore Corp. So when he wasn’t himself, not pulling his weight, backing out of the harness, farm manager Ned Niemiec worried about Windsor’s heart.

Two other horses in the team had shown these signs in recent years, he said, and the diagnosis had been atrial fibrillation causing an irregular heart rhythm. So when their primary veterinarian suspected the same condition, Mr. Niemiec loaded up Windsor for the seven-hour drive from Lakeville, Mass., to New Bolton Center in Kenneth Square, Pa. “We’ve enjoyed a strong relationship with New Bolton for many years,” said Mr. Niemiec, who manages all aspects of the Hallamore Clydesdales. “We believe in the top, top reputation, especially in the cardiac area.”

Virginia Reef, DVM, director of Large Animal Cardiology and Diagnostic Ultrasonography at New Bolton Center, is an expert in equine a-fib.

“When a horse has a big heart, atrial fibrillation is more likely,” said Reef, who is also chief of the Section of Sports Medicine and Imaging.

A Horse with Heart

Windsor, foaled in England, is a 12-year-old gelding that weighs more than 2,200 lbs and stands more than 18 hands high. “He’s huge,” Dr. Reef said.

Distinctive, with a large white blaze on his face, Windsor is one of 17 Clydesdales that live on the 40acre farm of Dennis Barry, who for nearly 45 years has indulged his passion for the breed with his eighthorse hitch.

Mr. Barry owns Hallamore, a heavy-hauling trans-

B y 16

L o u i s a

Issue 2/2015 | ModernEquineVet.com

S h e p a r d

portation and equipment company that started in 1895 hauling loads with horses. To promote the company and foster positive public relations, a team of eight Clydesdales pulls an orange wagon, built in 1899, in parades and at local fairs.

“Windsor is one of the stars of our operation here,” Mr. Niemiec said. “He’s a wonderful horse. He’s one of the favorites in the barn. He’s not only handsome, he works well, too, and he has a great personality. Willing and attentive, alert and easy, he wants to do his job.”

There was no question that the Hallamore team would do everything they could to get Windsor the care he needed.

Photo Courtesy of New Bolton Center

Clydesdale caption: Winsor, the Clydesdale, about to undergo an EKG.

Photo Courtesy of Hallamore Corporation

Cardiac Care at New Bolton Center

An electrocardiogram (EKG) confirmed the diagnosis of atrial fibrillation, Dr. Reef said. Windsor’s heartbeat was more than 80 beats per minute and did not settle down, compared with a usual rate of 50 beats per minute. Dr. Reef treated him with sotalol, an anti-arrhythmic drug with beta-blocking properties. “We wanted to slow the heart rate,” she said.

An echocardiogram confirmed that Windsor did not have obvious structural heart disease, such as a leaking heart valve.

One of the ways to “convert” atrial fibrillation is to give the horse IV doses of quinidine gluconate, Dr. Reef said. This drug can be successful if the atrial fibrillation is new, and the horse does not have structural heart disease, like Windsor.

“We gave him small doses for a good part of the day, and the a-fib resolved,” Dr. Reef said.

The treatment worked, but the veterinarians had to watch for “premature” heartbeats, extra beats just before the regular beats. Windsor

was on a continuous electrocardiogram around the clock.

“He did have a few atrial premature heartbeats,” Dr. Reef said.

“And when he was on the trailer getting ready to go home, we heard a number of them.”

Windsor was sent home on the drug sotalol to suppress the atrial premature heartbeats. Dr. Reef also gave him benazepril, a drug that has been proven to help prevent re-occurrence of atrial fibrillation in humans.

In addition, she recommended potassium chloride supplements because the level of potassium excreted by Windsor’s kidneys was low. A potassium deficiency can cause the premature beats, and those premature beats can trigger atrial fibrillation, Dr. Reef said. “If the body is depleted of potassium, this can make it more likely for afib to occur,” she said.

Heading Home With a Heart Monitor

Mr. Niemiec went home with a 24-hour EKG to monitor Windsor’s heart. He did the recordings two weeks later, both standing in the stall, and while exercising, and sent the results to Dr. Reef.

Ultimately, they weaned him off the drugs and his heart rhythm stayed steady. Windsor’s heart has made it past the critical fourmonth period, which is when most relapses occur, Dr. Reef said.

“He’s past the first marker, which is good,” Dr. Reef said.

“But he could still experience a recurrence. So they need to make sure his electrolyte status is good, and make sure he gets potassium supplementation, especially if he works very hard.”

“He’s right as rain,” Mr. Niemiec said. “He seems to tolerate the work, whatever we ask him to do.”

MeV ModernEquineVet.com | Issue 2/2015

17

technician update

Do Zebras need hoof trims?

Carrie Cramer, RVT

Photo Courtesy Carrie Cramer, R.V.T.

An important part of caring for a horse includes keeping their hooves trimmed properly since most of these horses are kept in some form of confinement.

Their exotic counterparts, such as zebra and Przewal-

Clockwise: Author drawing a blood sample Farrier in action Preparing to collect a urine sample

ski’s wild horse, roam free and are able to wear down their hooves as they cover miles of terrain.

Although zebras in a zoological setting might have large exhibit spaces, these spaces are nothing like roaming over the African savanna. Routine hoof trimming is necessary for maintaining the health of these species.

Exotic equines are not amenable to manual restraint, so we must anesthetize them to perform even basic husbandry. At the San Diego Zoo Safari Park, 18

Issue 2/2015 | ModernEquineVet.com

our veterinarians use combinations of opioids and other anesthetic drugs.

We plan these events days or sometimes weeks in advance because multiple departments are involved and the animal may need to be moved or isolated prior to the procedure. A team of veterinarians, technicians and keepers participate to expedite the procedure.

As the technician team members, we prepare paperwork and supplies the day before the procedure.

On the morning of, we load equipment into the veterinary truck and have a preprocedural meeting with all involved.

Since these animals have a large flight distance, the veterinarians must use a remote delivery system to administer the anesthetic drugs. At the Safari Park, we use carbon dioxide rifles with darts. Depending on the drugs used, induction usually lasts from 3 to 10 minutes. However, there can be variables, such as a partial injection, a dart that bounced off of the animal or injection into a fat pad that may delay induction.

In this case, a Hartmann’s mountain zebra (Equus zebra hartmannae) was darted with carfentanil (Zoo-Pharm) detomidine (Pfizer), ketamine (ZooPharm) and butorphanol (ZooPharm). Her induction lasted 12½ minutes due to a partial injection. Despite this, she achieved a good plane of anesthesia for the procedure.

Once the animal is recumbent, the veterinarian and keepers will restrain and position the patient.

For hoof trimming we put the horse in lateral recumbency and position the legs away from any walls or structures to avoid injury if the horse were to rouse.

We place a mattress pad under the head to protect the down eye and keep the neck extended for ease

of respirations. We flush and moisten the eyes, then drape with a towel to avoid visual stimulation.

Supplemental oxygen is placed by a tube in the nares or an endotracheal tube. Then we place monitoring equipment on the patient. A pulse oximeter is routinely used to monitor heart rate and oxygenation. Stethoscopes are also readily available.

While the farrier begins to work on the hooves, with a different orientation in lateral recumbency, the technicians will collect any biological samples and give injections while the veterinarian is performing a physical examination, including an oral examination.

Collecting a blood sample is given the first priority so as to draw a sample that is as close to ‘normal’ as possible. We try to avoid a stress leukogram that could be seen if we prolong the collection time from recumbency. Injections may include an anthelminthic, antibiotic, anti-inflammatory and vaccines.

Simultaneously, another technician or veterinarian is monitoring respiration, heart rate and temperature. In some cases there may only be one technician,

so these tasks are prioritized on a case-by-case basis.

Diagnostics included were urine collection and ultrasound to confirm pregnancy. A foal was confirmed with ultrasound and rectal palpation.

The final step is to administer antagonists. Naltrexone (ZooPharm) is an opioid antagonist and reverses the effects of the carfentanil and butorphanol. Atipamezole (Pfizer) is an α-2 antagonist and reverses, in this case, the detomidine. Both drugs were given as intramuscular injections. The patient was standing within 3 minutes after reversal agents were given. Her recovery was smooth and uncomplicated.

All of this zebra’s laboratory results were within normal limits. She gave birth to a live foal three months later.

MeV

About the author

Carrie Cramer, RVT, is a veterinary technician at the San Diego Zoo Safari Park, 15500 San Pasqual Valley Road, Escondido, CA 92127.

AAEVT Mission Statement: To promote the health and welfare of the horse through the education and professional enrichment of the equine veterinary technician and assistant.

www.aaevt.org

Are you aware the AAEVT is a professional equine association for not only your technicians and assistants but for your entire support staff as well? Membership is open to all veterinary technicians, assistants, practice managers, support staff and those employed or involved in the veterinary health care industry worldwide. We offer student memberships for those enrolled in an AVMA/CVMA accredited VT program.

The primary objective of the AAEVT is to provide continuing education opportunities and training avenues, as well as to improve communications and enhance networking. By keeping members updated regarding current skills and issues within the profession, we continue to educate and promote the role of the technician as a profession to the veterinary community and general public. The end result being, to work more effectively and efficiently with veterinarians to continue to add value and provide the best care possible to improve the health and welfare of the horse.

Member benefits include:

• Equine specific continuing education opportunities which include • Eligibility for credentialed technicians to join the AAEVT Academy, members only registration fee discounts at AAEVT hosted regional AEVNT (Specialty in Equine Nursing).

CE meetings and at the annual AAEP convention, including TEVA and NEAEP. (Savings of $200.00 or more!)

• 20% discount on purchase price of the AAEVT Equine Manual for Veterinary Technicians published by Blackwell Publishing.

• Networking opportunities to enhance staff member’s training opportunities that can add value to any practice.

• NTRA, Platinum Performance and Working Advantage member benefits.

• Biannual newsletters and our weekly email newsflash “HoofBeats” on Industry news.

• Scholarships toward AVMA programs, AAEVT online Equine Certificate program and attend ing Regional CE meetings • Full website access, including our Career Center with job opportunity postings.

• Eligibility to be invited to attend the Purina Equine Veterinary Technician Conference in St. Louis as a guest of • On-line access to industry articles, proceedings and webinars.

Purina – all expenses paid!

• Eligibility to participate in the ACT AAEVT On-Line Equine Certification Program.

Encourage and support your staff to join today!

For additional information, to join online, or to obtain a membership application, visit www.aaevt.org.

ModernEquineVet.com | Issue 2/2015

19

The Modern

Equine Vet

Reach your veterinarians wherever they are, whenever they want.

FOR ADVERTISING RATES AND INFORMATION, EMAIL Robin Gellar