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That first bag

Choosing initial fluids for foal emergency New technique for finding ophthalmic foreign bodies Standing MRI's use in preventing complete condyle fractures Technician Update: Anesthesia monitoring during MRI

Vol 3 Issue 3 2014

Table of Contents

Cover story:

4 How to choose that first bag of IV fluids for foal emergency Cover photo by Shutterstock/ Eduard Kyslynskyy

ophthalmology

Safer, faster way to diagnose ophthalmic foreign bodies ....................................... 3 Imaging

Standing MRI might help prevent complete condylar fractures..........................10 Dentistry

Don't forget the teeth!.........................................................................................................12 Technician Update

Advanced imaging requires fundamental monitoring techniques....................15 News

Horse gait controlled by genetic mutation ....................8 Abaxis awarded US Army contract......................................9 AHT launches large EGS vaccine trial..............................17 Adequan now available.......................................................17 AVMA admits acupuncture academy into House of Delegates................................................................17 The Modern

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ophthalmology

Safer, faster way to diagnose ophthalmic foreign bodies A human medicine diagnos-

tic technique is allowing veterinary ophthalmologists to detect and diagnose foreign bodies faster.

Horses face high risks of developing eye problems, especially from foreign bodies. Clinicians at the Cornell Universty Hospital for Animals are the first to show how horses with these microscopic foreign bodies can benefit from in vivo corneal confocal microscopy, a non-invasive human clinical technique that provides microscopic images of the cellular structure of the living cornea without a scratch. The new images are comparable to in-vitro histochemical techniques. The non-invasive technology has huge clinical potential for investigating many corneal diseases.

Dogs and cats first

Eric Ledbetter, DVM, DACVO, associate professor of ophthalmology, began adapting the technique in dogs and cats, where he discovered two infectious eye diseases that had never been described before. He then turned to horses, pioneering a clinical research program to develop and validate non-invasive eye imaging in a species particularly poised to benefit from it. His findings were published online in the journal

Veterinary Ophthalmology.

“Horses have prominent eyes and live in environments that put their eyes at risk of trauma,” said Ledbetter. “They frequently have diseases of the ocular surface and other eye problems for which corneal confocal microscopy will be particularly useful."

Equine fungal keratitis

For example, equine fungal keratitis is a hard problem to diagnose — regular culturing methods of diagnosing fungal infections can take 10 to 14 days for results to come back, creating long treatment delays.

Using an in vivo corneal confocal microscope with a focal depth of 1.5 mm he adapted for use on horses, Ledbetter demonstrated its ability to repeatedly examine and take images all the way through a horse’s 1 mm-thick cornea — the eye’s first line of defense and a frequent site of injury and infection. Confocal microscopy gets immediate results without a biopsy.

Ledbetter has used it in clinics to help find and characterize tumors, scratches, foreign bodies, infections, immune-mediated ocular diseases, and other eye problems. He has published articles describing the normal features of

the equine cornea as viewed using in vivo confocal microscopy and the use of the technique to diagnoses equine fungal keratitis.

But when it came to identifying microscopic corneal foreign bodies using the new technique, he first had to validate its accuracy. By collecting images of horses’ eyes with foreign bodies and comparing them to results from traditional biopsy-based diagnostic methods like cytology and histopathology, he validated confocal microscopy as a quicker non-invasive technique to image and diagnose this eye problem accurately.

“With any new technology like this, you can take a lot of images but no one knows for sure what the images represent,” said Ledbetter.

“By concurrently using both new and preexisting techniques, we compiled and published evidence that the findings match. This paves the way for veterinarians to definitively diagnose eye diseases in horses with only this new technology, minimizing impact on the eye and saving time to get patients treatment faster.”

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Dr. Eric Ledbetter from Cornell University performing in vivo corneal confocal microscopy, a non-invasive human technique, on an equine patient.

Photo courtesy of Cornell University Hospital for Animals

For more information: Ledbetter EC, Irby NL, Schaefer DM. In vivo confocal microscopy of corneal microscopic foreign bodies in horses. Vet Ophthalmol. 2014 Jan 13. doi: 10.1111/vop.12139. [Epub ahead of print] http://www.ncbi.nlm.nih.gov/pubmed/24417756 ModernEquineVet.com | Issue 3/2014

3

cover story

How to choose your first bag of

IV fluids for foal in trouble information when they get called out to a foal emergency and limited room on the truck to prepare for that emergency.

“When you are in practice and are called out to an emergency, you have to make determinations about what types of IV fluids you are going to use with limited information. Clinpath data generally is not readily available, but you know that your aim will be to restore fluid in various body compartments,” said Pamela W. Wilkins, DVM, MS, PhD, DACVIM-LA, DACVECC, of the University of Illinois College of Veterinary Medicine in Champaign-Urbana, Ill. The choice will depend on the patients you see, Wilkins said, but hypertonic saline (1-L bags), isotonic polyionic crystalloid fluids with a normal strong ion difference (one to four 1-L bags) and 1-L bags of 5% dextrose in water are good to have if you are handling a foal ambulatory emergency.

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Wilkins conducted a brief, informal survey of board-certified large animal internists (ACVIM) and/or board-certified emergency and critical care (ACVECC) veterinarians. She provided several scenarios and asked what their initial bag of fluid would be for that patient. She reported the results at the recent 59th Annual Convention of the American Association of Equine Practitioners in Nashville, Tenn.

tion, so she wouldn’t give it.

“It drove them crazy,” she admitted a little deviously. “There was a level of frustration that certainly came through. But I was in practice and I did not have that information when I was making decisions. I think it is important to make good fluid decisions without having every bit of clinpath data available,” she said.

“I also did not give them detailed physical examination findings because frequently when you are throwing stuff into your truck to see patients, you don’t have physical examination findings, yet, and you won’t have them until you get there. So, knowing what to carry as you are heading on out can be pretty useful.”

She asked a single question: “What do you use or add to your first bag of fluids?”

The foal cases were:

• 10-minute-old foal delivered from a prolonged dystocia of about 120 minutes with an APGAR score of 6 • Obtunded, hypothermic minimally responsive 24-hourold foal • 6-day-old foal with diarrhea All 20 veterinarians who responded wanted more information, she said, but veterinarians frequently have to make these decisions quickly with little informa-

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The first case

• 10-minute-old foal delivered from a prolonged dystocia of

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Shutterstock/Yongkiet jitwattanatam

Veterinarians have limited

about 120 minutes with an APCAR score of 6 There was a variety of fluid approaches for this case from none with close observation to between one-half and 1 L of crystalloid replacement fluid. Most would have used some type of isotonic polyionic crystalloid replacement fluid with a normal strong ion difference.

“The thing to remember here is that most babies are not born dehydrated and they generally don’t need fluids unless there has been some type of blood loss or severe in utero sepsis associated with hypotension,” Wilkins said. “So, we don’t generally have to aggressively fluid resuscitate these brand new newborns.”

The APGAR score suggested a mild to moderate asphyxiation, according to Wilkins, and veterinarians wanted to supplement the fluids. The most common was dextrose for energy support, thiamine for intracellular energy metabolism, vitamin C and DMSO are antioxidants and magnesium could be neuroprotective.

The second case

• Obtunded, hypothermic minimally responsive 24-hourold foal The symptoms represent a range of conditions from severe sepsis to hypoxic ischemic disease. “The initial treatment of those foals was pretty uniform and aimed at stabilization and renewing intravascular volume, in

Black box warning on hydroxyethyl starch solutions The US Food and Drug Administration (FDA) added a black box warning about the use of hydroxyethyl starch products.

Hydroxyethyl starch (HES) solutions are used for the treatment of hypovolemia when plasma volume expansion is desired. Recent data have associated administration of these products with an increased risk of severe adverse events when used in certain human patient populations, which would be appropriate to pay attention to for very sick equine patients, including patients with decreased renal function, according to Pamela W. Wilkins, DVM, MS, PhD, DACVIM-LA, DACVECC, of the University of Illinois College of Veterinary Medicine in Champaign-Urbana, Ill. Link to FDA site for more information: http://www.fda.gov/biologicsbloodvaccines/safetyavailability/ucm358271.htm

addition to providing an energy source,” she said.

All of the veterinarians chose to administer isotonic polyionic crystalloid replacement fluids at bolus rates 20 mL/kg over 20 minutes, repeating as necessary. “I usually try to limit that to a total of four 1 L boluses to a 50 kg foal.

You reassess in between boluses to see if they need another one,” Wilkins said.

Most recognized an immediate need for some type of energy support and piggybacked dextrose in the constant rate infusion.

“This is a bit complex. If you set a rate of 250 mL/hour to a 50 kg foal of a 5% dextrose solution, you will hit that target,” she said.

“So you don’t have to do any fancy calculations.” One could also add a 1% dextrose solution to the first crystalloid bag (20 mL 50% dextrose added to a 1-L bag of crystalloid) followed by CRI of dextrose at 4 mg/kg/min.

“I tend to include my first dose of antimicrobials in that first bag,

so I’ve got that covered, too.”

Third case

• 6-day-old foal with diarrhea Many were really uncomfortable with this patient and wanted more information, she said, because the amount of fluid loss can be so variable depending on the type and severity of disease.

“Although the majority chose isotonic polyionic crystalloids, many chose saline as an initial resuscitation fluid,” she said.

Foals of this age can have severe and unpredictable electrolyte imbalances, such as hyponatremia and hypochloremia, which prompted them to reach for saline as the first bag. Others thought the greater benefit came from using isotonic polyionic crystalloid fluids because they were closer to normal plasma values.

In cases such as this, fluid replacement should be aimed at volume replacement and then electrolyte replacement as more clinpath data become available.

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What fluid should be on the truck for an adult emergency?

Hypertonic saline (1-L bags), isotonic polyionic crystalloid fluids with a normal strong ion difference (1 L and 3- to 5-L bags) and 5% dextrose in water (1-L bags) are commonly used.

For adults, consider 2 L 7.5% hypertonic saline; 20-30 L isotonic polyionic crystalloid.

Shutterstock/ Rob Byron

Common additives: thiamine, calcium, magnesium, polymyxin B. Other fluids might be needed for your particular patients.

ModernEquineVet.com | Issue 3/2014

5

Easy does it.

Equine Protozoal Myeloencephalitis (EPM) can strike anytime, anywhere. Be prepared with Protazil®.

Only FDA-approved pelleted top dress for the treatment of EPM Safe and accurate dosing with calibrated scoop Easier to use than paste, less stress for you and the horse Effective, less expensive alternative to Marquis™ Contact your Merck Animal Health representative to find out more.

Visit protazil.com We’re for the Horse™

Protazil is contraindicated in horses with known hypersensitivity to diclazuril. Safe use in horses used for breeding purposes, during pregnancy or in lactating mares has not been evaluated. The safety of Protazil with concomitant therapies in horses has not been evaluated. See related page in this issue for details. For use in horses only. Do not use in horses intended for human consumption. Not for human use. Keep out of reach of children.

556 Morris Avenue • Summit, NJ 07901 • merck-animal-health-usa.com • 800-521-5767 Copyright © 2013 Intervet Inc., d/b/a Merck Animal Health, a subsidiary of Merck & Co., Inc. All rights reserved. Photography: Vince Cook. 50035 4/13 EQ-PHARM-VET-1219-AD

ModernEquineVet.com | Issue 3/2014

7

ANTIPROTOZOAL PELLETS

News Notes

(1.56% diclazuril)

FOR ORAL USE IN HORSES ONLY For the treatment of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona in horses.

CAUTION Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian.

NADA #141-268 Approved by FDA DESCRIPTION Diclazuril, (±)-2,6-dichloro-α-(4-chlorophenyl)-4-(4,5 dihydro-3,5-dioxo-1,2,4-triazin-2(3H)-yl) benzeneacetonitrile, has a molecular formula of C17 H 9 CI 3 N4O2, a molecular weight of 407.64, and a molecular structure as follows:

Diclazuril is an anticoccidial (antiprotozoal) compound with activity against several genera of the phylum Apicomplexa. PROTAZIL® (diclazuril) is supplied as oral pellets containing 1.56% diclazuril to be mixed as a top-dress in feed. Inert ingredients include dehydrated alfalfa meal, wheat middlings, cane molasses and propionic acid (preservative).

INDICATIONS PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets are indicated for the treatment of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona in horses.

DOSAGE AND ADMINISTRATION Dosage: PROTAZIL® (1.56% diclazuril) is administered as a top dress in the horse’s daily grain ration at a rate of 1 mg diclazuril per kg (0.45 mg diclazuril/lb) of body weight for 28 days. The quantity of PROTAZIL® necessary to deliver this dose is 64 mg pellets per kg (29 mg pellets/ lb) of body weight.

Administration: To achieve this dose, weigh the horse (or use a weigh tape)). Scoop up PROTAZIL® to the level (cup mark) corresponding to the dose for the horse’s body weight using the following chart: Weight Range of Horse (lb) 275 - 524 525 - 774 775 - 1024 1025 - 1274

mLs of Pellets 20 30 40 50

Weight Range of Horse (lb) 1275 - 1524 1525 - 1774 1775 - 2074 -

Horse gaits controlled by genetic mutation spread by humans From the Faroe Pony to the Spanish Mustang, fewer animals have played such a central role in human history as the horse. New research in Animal Genetics reveals that a horse’s gait, an attribute central to its importance to humans, is influenced by a genetic mutation, spread by humans across the world.

mLs of Pellets 60 70 80 -

One 2-lb bucket of PROTAZIL® will treat one 1100-lb horse for 28 days. One 10-lb bucket of PROTAZIL® will treat five 1100-lb horses for 28 days.

CONTRAINDICATIONS Use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets is contraindicated in horses with known hypersensitivity to diclazuril.

WARNINGS For use in horses only. Do not use in horses intended for human consumption. Not for human use.

Keep out of reach of children.

PRECAUTIONS The safe use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. The safety of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets with concomitant therapies in horses has not been evaluated.

ADVERSE REACTIONS There were no adverse effects noted in the field study which could be ascribed to diclazuril.

To report suspected adverse reactions, to obtain a MSDS, or for technical assistance call 1-800-224-5318.

CLINICAL PHARMACOLOGY The effectiveness of diclazuril in inhibiting merozoite production of Sarcocystis neurona and S. 1 falcatula in bovine turbinate cell cultures was studied by Lindsay and Dubey (2000). Diclazuril inhibited merozoite production by more than 80% in cultures of S. neurona or S. falcatula treated with 0.1 ng/mL diclazuril and greater than 95% inhibition of merozoite production (IC 95 ) was observed when infected cultures were treated with 1.0 ng/mL diclazuril. The clinical relevance of the in vitro cell culture data has not been determined.

PHARMACOKINETICS IN THE HORSE The oral bioavailability of diclazuril from the PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets at a 5 mg/kg dose rate is approximately 5%. Related diclazuril concentrations in the cerebrospinal fluid (CSF) range between 1% and 5% of the concentrations observed in the plasma. Nevertheless, based upon equine pilot study data, CSF concentrations are expected to 2 substantially exceed the in vitro IC 95 estimates for merozoite production (Dirikolu et al., 1999) .

Due to its long terminal elimination half-life in horses (approximately 43-65 hours), diclazuril accumulation occurs with once-daily dosing. Corresponding steady state blood levels are achieved by approximately Day 10 of administration.

EFFECTIVENESS Two hundred and fourteen mares, stallions, and geldings of various breeds, ranging in age from 9.6 months to 30 years, were enrolled in a multi-center field study. All horses were confirmed EPM-positive based on the results of clinical examinations and laboratory testing, including CSF Western Blot analyses. Horses were administered PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets at doses of 1, 5, or 10 mg diclazuril/kg body weight as a top-dress on their daily grain ration for 28 days. The horses were then evaluated for clinical changes via a modified Mayhew neurological scale on Day 48 as follows: 0. Normal, neurological deficits not detected.

1. Neurological deficits may be detectable at normal gaits; signs exacerbated with manipulative procedures (e.g., backing, turning in tight circles, walking with head elevation, truncal swaying, etc.).

2. Neurological deficit obvious at normal gaits or posture; signs exacerbated with manipulative procedures.

3. Neurological deficit very prominent at normal gaits: horses give the impression they may fall (but do not) and buckle or fall with manipulative procedures.

4. Neurological deficit is profound at normal gait: horse frequently stumbles or trips and may fall at normal gaits or when manipulative procedures were utilized.

5. Horse is recumbent, unable to rise.

Each horse’s response to treatment was compared to its pre-treatment values. Successful response to treatment was defined as clinical improvement of at least one grade by Day 48 ± conversion of CSF to Western Blot-negative status for S. neurona or achievement of Western Blot-negative CSF status without improvement of 1 ataxia grade.

Forty-two horses were initially evaluated for effectiveness and 214 horses were evaluated for safety. Clinical condition was evaluated by the clinical investigator’s subjective scoring and then corroborated by evaluation of the neurological examination videotapes by a masked panel of three equine veterinarians. Although 42 horses were evaluated for clinical effectiveness, corroboration of clinical effectiveness via videotape evaluation was not possible for one horse due to missing neurologic examination videotapes. Therefore, this horse was not included in the success rate calculation.

Based on the numbers of horses that seroconverted to negative Western Blot status, and the numbers of horses classified as successes by the clinical investigators, 28 of 42 horses (67%) at 1 mg/kg were considered successes. With regard to independent expert masked videotape assessments, 10 of 24 horses (42%) at 1 mg/kg were considered successes. There was no clinical difference in effectiveness among the 1, 5, and 10 mg/kg treatment group results.

Adverse events were reported for two of the 214 horses evaluated for safety. In the first case, a horse was enrolled showing severe neurologic signs. Within 24 hours of dosing, the horse was recumbent, biting, and exhibiting signs of dementia. The horse died, and no cause of death was determined. In the second case, the horse began walking stiffly approximately 13 days after the start of dosing. The referring veterinarian reported that the horse had been fed grass clippings and possibly had laminitis.

ANIMAL SAFETY PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets were administered to 30 horses (15 males and 15 females, ranging from 5 to 9 months of age) in a target animal safety study. Five groups of 6 horses each (3 males and 3 females) received 0, 5 (5X), 15 (15X), 25 (25X) or 50 (50X) mg diclazuril/kg (2.27mg/lb) body weight/day for 42 consecutive days as a top-dress on the grain ration of the horse. The variables measured during the study included: clinical and physical observations, body weights, food and water consumption, hematology, serum chemistry, urinalysis, fecal analysis, necropsy, organ weights, gross and histopathologic examinations. The safety of diclazuril top-dress administered to horses at 1 mg/kg once daily cannot be determined based solely on this study because of the lack of an adequate control group (control horses tested positive for the test drug in plasma and CSF). However, possible findings associated with the drug were limited to elevations in BUN, creatinine, and SDH and less than anticipated weight gain.

Definitive test article-related effects were decreased grain/top-dress consumption in horses in the 50 mg/kg group.

In a second target animal safety study, PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets were administered to 24 horses (12 males and 12 females, ranging from 2 to 8 years of age). Three groups of 4 horses/sex/group received 0, 1, or 5 mg diclazuril/kg body weight/day for 42 days as a top-dress on the grain ration of the horse. The variables measured during the study included physical examinations, body weights, food and water consumption, hematology, and serum chemistry. There were no test article-related findings seen during the study.

STORAGE INFORMATION Store between 15°C to 30°C (59°F to 86°F).

HOW SUPPLIED PROTAZIL® (1.56 % diclazuril) Antiprotozoal Pellets are supplied in 2-lb (0.9 kg) and 10-lb (4.5 kg) buckets.

REFERENCES 1. Lindsay, D. S., and Dubey, J. P. 2000. Determination of the activity of diclazuril against Sarcocystis neurona and Sarcocystis falcatula in cell cultures. J. Parasitology, 86(1):164–166.

2. Dirikolu, L., Lehner, F., Nattrass, C., Bentz, B. G., Woods, W. E., Carter, W. E., Karpiesiuk, W. G., Jacobs, J., Boyles, J., Harkins, J. D., Granstrom, D. E. and Tobin, T. 1999. Diclazuril in the horse: Its identification and detection and preliminary pharmacokinetics. J. Vet. Pharmacol.

Therap. 22:374–379.

May 2010 Intervet Inc. 56 Livingston Ave, Roseland, New Jersey 07068 © 2010 Intervet Inc. All rights reserved.

08-10 211.x.3.1.0

The team, led by Dr. Leif Andersson from the Swedish University of Agricultural Sciences, explored the distribution of a mutation in the DMRT3 gene that affects the gait of horses, known as the “gait keeper.”

“All over the world, horses have been used for everyday transportation, in military settings, cattle herding and agricultural power, pulling carriages and carts, pleasure riding or racing,” said Andersson. “Over the centuries, horse populations and breeds have been shaped by humans based on the different purposes for which the animals were used.”

The DMRT3 gene controls a range of gaits as well as pace. From racing to pleasure riding, many species have been bred to encourage smoothness of gait.

“For example, the Paso Fino is a breed from Latin America in which the frequency of the gait keeper mutation is nearly 100%. It is claimed that the Paso Fino gait is so smooth that you can have a glass of wine in your hand without letting it spill,” said Andersson.

The team analyzed 4,396 horses from 141 breeds around the world and found that the gait keeper mutation is spread across Eurasia from Japan in the East, to the British Isles in the West, on Iceland, in both South and North America, and also in breeds from South Africa.

“Humans have spread this mutation across the world primarily because horses carrying this mutation are able to provide a very smooth ride, in some breeds referred to as a running walk,” said Andersson. “During such ambling gaits the horse has at least one foot on the ground that means that the vertical movement of the rider is minimal.”

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For more information: Promerová M, Andersson LS, Juras R, et al. Worldwide frequency distribution of the ‘Gait keeper’ mutation in the DMRT3 gene. Animal Genetics, 2014; DOI: 10.1111/age.12120 8

Issue 3/2014 | ModernEquineVet.com

x

news notes

Abaxis awarded US Army contract Abaxis Inc., which provides instruments, consumables and laboratory services for veterinarians, recently contracted with the US Army to provide veterinary diagnostic laboratory services to the Veterinary Services Central Fund (VSCF).

This contract provides pointof-care laboratory diagnostic instruments and reagents, as well as reference laboratory services through Abaxis Veterinary Reference Laboratories (AVRL) to about 118 Army veterinary activities in the United States and its territories. The contract is for Shutterstock/ alisafarov one year with options for four additional one-year periods with maximum order/

quantity limitations of $3 million per year. "Based on the merit of the Abaxis diagnostic product portfolio, we are pleased to receive the award from the Department of the Army. Historically, we have had a strong relationship with all US military branches both on the human and veterinary market. We are excited to standardize all of the 118 veterinary clinics as this will allow for an easier transition and shorter training times for the end users, providing better results to their clients. We look forward to continue to support our Armed Forces," said Randall Knick, director of government affairs at Abaxis.

MeV

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ModernEquineVet.com | Issue 3/2014

9

imaging

Standing MRI

might help prevent

complete condylar fractures A racing horse is truly a marvel

Photo courtesy of Hallmarq

of biomechanical engineering. During the gallop gait, when a 1,100- to 1,200-lb Thoroughbred is racing up to 40 mph, each leg individually holds up the entire horse. And during each race, one animal musters up just a little more speed and force to reach the winner’s circle.

For this to occur, the bones of these elite athletes must be strong.

“Bone that is standing around in the field does not see a lot of force, but bone that has to go down the race track and handle the forces of the gallop gait is bone that needs to be stronger,” said John Peloso, DVM, MS, DACVS, owner and partner at The Equine Medical Center of Ocala in Florida.

Training and exercise helps strengthen that bone, which responds to this stress by undergo-

Left shows a normal MRI; right shows edema.

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Issue 3/2014 | ModernEquineVet.com

ing cycles of bone deposition and bone resorption. This adaptive bone remodeling is necessary to withstand the increased load and bone stresses that all athletes — from ballet dancers to Thoroughbred race horses — endure as they grow, mature, train and compete.

However, sometimes the adaptive cycle does not occur at the rate needed to support the stress forces the bone undergoes. If the bone is unable to adapt fast enough to handle the load, it experiences nonadaptive stress and is at risk of fracturing during continued stress.

“At that kind of weight with these kinds of forces and speed, if the bone fractures it has the potential to be catastrophic,” Peloso said.

Of particular concern for the racehorse is the condylar fracture of the fetlock joint, which is a fracture

of the distal third metacarpal (cannon) bone. This can occur in the front or hind limbs and can range from a small fissure that does not extend far from the joint surface (a microfracture) to a complete break.

“Condylar fractures are almost exclusively the result of cyclic overloading of the fetlock joint during training and racing leading to accumulation of micro-damage and ultimate failure of the bone if this outstrips intrinsic repair,” said Sarah E. Powell, MA, VetMB, Assoc. (LA) ECVDI, MRCVS, a partner at the Rossdale & Partners in Newmarket, England.

Small fissures are common in Thoroughbred and Standardbred racehorses or horses that are used for high-level endurance racing.

They are less common in horses that compete in jumping or dressage, but

raphy. But original MRIs required general anesthesia and, due to the associated risks to the horse, were not widely used in equine imaging.

Today, however, veterinarians have access to a standing MRI developed by Hallmarq. The standing MRI can detect pathology earlier than radiography and can broadly differentiate between an active and an inactive fissure, which enables the veterinarian to offer a risk assessment for complete fracture.

Standing MRI has several advantages over other imaging, the two veterinarians said. No general anesthesia is required, and under the Jockey Club medication rules, standing MRI can be used close to racing, depending on the sedation given — about three days out minimally. There is little disruption to training, and often no overnight stay is required.

“Eliminating the need for general anesthesia is one of the best arguments in favor of standing MRI,” Peloso said. “We are concerned about the risks created by recovery from general anesthesia, especially if we are evaluating horses that possibly have incomplete fractures.

That violent act of recovering from general anesthesia on a horse that is not orthopedically stable could result in the very thing we are trying to prevent.”

A veterinarian who diagnoses the edema that signals a fissure on MRI can make recommendations to reduce the stress on the bone and allow it to heal. A fissure does not necessarily preclude the horse from training.

“Fissures are extremely prevalent, so resting every horse with a fissure would be detrimental to the racing and veterinary industries,” said Powell. “We try to assess how active the fissure is and give the horse a risk assessment. Some are deemed not active, and the horse can continue with caution. Some have a differ-

Courtesy of Dr. Powell, Rossdale & Partners, Newmarket

they can occur. Complete condylar fractures occur almost exclusively in horses that compete at high speeds.

“Fetlock and other musculoskeletal injuries have a large impact on the racing industry,” Powell said.

“Concerns have been raised over the welfare of the horses, economic loss, rider safety and the negative impact that a horse’s injury has on the public perception of the sport.”

Veterinarians can help assure the best outcome for the horse by isolating the small fissures or microfractures before they become complete fractures and reducing the stress of training to less galloping exercise and more jogging exercise until the bone can heal and strengthen.

Unfortunately, clinical signs can be as subtle as the horse being off its feed or not wanting to train when it usually loves the activity.

Some horses show no overt lameness prior to sustaining a catastrophic fracture. However, close appraisal of the horses to detect subtle or transient lameness could allow early intervention and direct those which need it to imaging.

“If we can identify the horses with fissures and those at risk of sustaining more severe injuries if they were to continue to train and race, we could potentially avoid some fatalities,” Powell explained.

Historically, radiographs were the only method of detecting early fetlock pathology. Radiographs are quick, inexpensive and widely available. However, the damage must be more advanced before it is can be seen on a radiograph.

Veterinarians turned to scintigraphy, which is more sensitive than radiographs in identifying some forms of bone pathology. Although bone scanning is very sensitive, it is not very specific for the disease process.

About 15 years ago, veterinarians started using magnetic resonance imaging (MRI), which is more specific, but less sensitive than scintig-

ent appearance on the MRI and are thought to carry greater risk. These either go to internal fixation or are allowed to rest so the bone can heal.”

If identified early enough, most horses do quite well, added Peloso.

For many, the horse’s routine is slowed down. They are permitted to train, but are usually prevented from doing speed work.

In an ideal world, a second MRI could be done after several months to reassess and continue proper management. “With standing MRI, we can manage the situation better, so horses could go back into full training sooner,” Peloso said.

Standing MRI enables veterinarians to find fissures early, which increases the need for a good relationship among the professionals handling the horse. The intimate triad of interaction that takes place among the trainer, the trainer’s veterinarian and the person performing the MRI before and after the diagnosis is made, is essential.

Because the problem is inside the marrow cavity of the bone, trademark clinical signs like joint fluid distension are not available to tell the veterinarian: “Hey, the problem is in MeV this fetlock!”

A complete condylar fracture.

ModernEquineVet.com | Issue 3/2014

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dentistry

Don’t forget the

teeth!

Equine Dental Vets is an organization dedicated to equine dentistry Many people think that equine dentistry is just floating the teeth, and many owners believe that just about anyone can perform equine “dentistry” from the trainer to the farrier.

Shannon Lee, BVSc MACVSc, who has been practicing solely equine dentistry since 2006 cringes when he thinks about how little owners think about equine dentistry.

Equine veterinarians and technicians must take the time to educate their clients about the importance of proper dental care for their horses.

The Modern Equine Vet had an email chat with Lee, founder and director of global operations at Equine Dental Vets, an organization dedicated to providing quality dental care to equine patients about this important issue.

Here’s what he had to say:

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Issue 3/2014 | ModernEquineVet.com

opposite. The issues around provision of correct treatment and training are worldwide problems, and they are not going away anytime soon. The profession needs a peak body that has clear goals and incorporates the views of its members.

Can you tell us about Equine Dental Vets?

We currently have around 400 members worldwide and we be-

Shutterstock/Nate Allred

Why did you feel the need to start Equine Dental Vets?

There is a clear need for a dedicated group focused primarily on this one key area of equine health and committed to moving beyond state, territory or country boundaries. Veterinarians around the world face similar issues and problems irrespective of language or location. Too often terms like “Inclusive” are used in the vet industry to describe exactly the

Teeth — isn't that one of those areas that owners and trainers (or farriers) think they can do themselves? Why shouldn't they?

Just as you wouldn't take your precious dog or cat to someone other than a skilled, licensed in-

Photo courtesy of Dr. Shannon Lee

gan in 2011. Equine dental vets is already the world’s largest equine dental group, it's membership is comprised of veterinarians who have undertaken postgraduate training in equine dentistry.

The group provides a platform for its members to communicate with one another across borders and continents, and through the use of innovative technology even across language barriers.

Members can access a wide range of support services and continuing education options as well as promotional materials.

One of the most recent innovations has been the development of an online equine dental charting system for members, removing the need for paper records and paving the way for collaborative global research on equine dental conditions.

The group also provides and supports hands on continuing education in many countries, with events this year in Africa, Asia, The Middle East, North America, Europe and South America.

I am extremely pleased with the overall response from veterinarians and horse owners to the groups public initiatives, but there is still a long way to go in educating both the public and the profession on equine dentistry.

dividual, your horse deserves the same care and protection. Equine dental vets have the training, licensing and skill to provide that piece of mind.

This might be a dumb question, but are teeth that "important"?

Horses only eat grass.

The question: Are teeth important is a good one, and actually highlights just how much work is still required to educate the public and our own profession about the importance of correct equine dental care. While having their own anatomy of the jaw and teeth, the horse's mouth still possesses nerves and blood vessels and they experience pain just as we do. Equine dental care is complex and will always be evolving.

Does dental pain affect performance?

Yes, dental care or lack there-

of can affect performance, but a very poor rider would not notice the difference and a very good rider may still be capable of getting results out of the horse So, it's far from that simple, a presentation I have given around the world can be found on YouTube it is called dentistry for thinking riders and it covers some of the key/common points to answer your question.

Dr. Shannon Lee examining a patient.

Can veterinarians increase their practice or help their bottom line by including dental checks?

Yes practices can and do benefit from membership and yes the potential to boost practice income is significant. I regularly write articles on aspects of equine dental care as it relates to practice management. One of our key objectives is to provide a supportive role for our members to grow their businesses. MeV

For more information: To see a video on dental care: http://file.wavesourcedesign.com/wl/?id=x&recipient=dmV0Ymxva2VAZ21haWwuY29t&file name=20140209_earth_globe_edv_members.wmv.

Veterinarians wishing to know more or inquire about membership can head to www.equinedentalvets.com ModernEquineVet.com ModernEquineVet.com| |Issue Issue3/2014 3/2014

13

AAEVT Membership

AAEVT* membership is open to US and international equine veterinary technicians, assistants, practice managers, and support staff employed in the veterinary industry. It is also open to students of AVMA/CVMA accredited programs

AAEVT Membership • • • • • • • •

Bi-Annual Newsletter Weekly “HoofBeats” email NEwsblast Full access to www.aaevt.org, including the Career Center and the Library Up-to-date information on the AAEVT Discounted registration for AAEVT Regional Meetings and the annual AAEP/AAEVT Convention NTRA, Working Advantage and Platinum Performance Benefits The opportunity to participate in the AAEVT Online Certification Program or to become a member of the AEVNT Academy-Specialty in Equine Veterinary Nursing • Scholarship opportunities.

• AAEVT’s Equine Manual for Veterinary Technicians (Blackwell Publishing 20% discount on purchase price) • Subscription to THE HORSE Magazine, compliments of Intervet Schering/Plough Opportunity to attend Purina’s Annual Equine Veterinary Technician Conference All Expenses paid!

AAEVT Objectives • • • •

Provide opportunities for CE, training, communication, and networking Educate the equine veterinary community and the public about our profession Inform Members of issues affecting our profession Assist in providing the best medical care to improve the health and welfare of the horse

AAEVT Online Equine Certification Program

• A three course, 10 module, equine-only online program offered through ACT • Geared toward Credentialed Veterinary Technicians, Assistants, Support staff, & Students • Areas of study include: equine medical terminology, anatomy and physiology, parasitology, laboratory, diagnostics, equine basics (breeds, wellness, husbandry,) diagnostic procedures, emergency medicine, restraint, pharmacology, surgical assistance and anesthesia, equine office procedures • A certificate of completion is awarded to those who: Successfully complete required courses Complete the list of required skills (per a supervising DVM who is an AAEP member) Attend an AAEVT regional CE symposium and participate in the we labs • Those individuals who successfully complete the programs will be recognized as AAEVT Certified Equine Veterinary Technicians / AAEVT Certified Equine Veterinary Assistants depending on their current designation. The certificate is recognized by the AAEVT and the AAEP but does not grant the credentialed status by the AVMA • For more information go to www.aaevt.4act.com or call 800-357-3182

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.

For more information visit www.aaevt.org

*American Association of Equine Veterinary Technicians and Assistants

technician update

Case presentation: Advanced imaging requires fundamental monitoring techniques A 2003 Warmblood mare used for upper level dressage, was referred to The Wisconsin Equine Clinic and Hospital for an MRI due to a right hindlimb lameness.

The following history was sent by the referring veterinarian. Patient came up lame on Jan. 15, 2013.

She is short striding on the RH, at a trot she is 2-­ ‐3/5 lame, moderate edema noted in the fetlock and through the tendon sheath area, and negative to hoof testers. The referring veterinarian also found an increased amount of fluid in the tendon sheath upon ultrasound evaluation, however, the tendons above and around the fetlock were within normal limits, and no fresh lesions were apparent. A block of the patient’s right hind fetlock, a basisesamoid block, improved the lameness 75%. Radiographs of the right hind did not reveal a definitive source of lameness. The owner elected to inject the right hind fetlock joint.

On Jan. 28, 2013, the owner contacted the referring veterinarian for a re-evaluation of the patient due to a worsening of lameness after the last injection. The referring veterinarian performed several blocks, all resulting in no change in lameness. At this point the owner terminated the exam and the patient was placed on stall rest for 3 months. After that time she was referred to hospital for a second opinion and possible magnetic resonance imaging (MRI).

Upon admittance to The Wisconsin Equine Clinic and Hospital, a physical exam was performed and was found to be within normal limits aside from a distinct soft tissue swelling through the pastern area of the right hind. The patient presented with a distinct right hind lameness evident at a walk and trot, and was noted to be a 3+/5 lame. Flexions of the distal limb resulted in a 4+/5 lameness, and she exhibited extreme pain on flexion. Hoof testers applied to the right hind were negative. A PD block resulted in 90% resolution of the lameness. Radiographs of the right hind identified mild periosteal reaction on the distal medial aspect of P1, but did not appear to be associated with the joint. Based on these findings an

MRI of the right hind foot, pastern and fetlock were recommended under general anesthesia.

Routine pre-anesthetic blood work was run and was found to be within normal limits. An intravenous catheter was placed and the patient was further prepared to be induced.

A routine anesthetic induction was performed with 8 cc xylazine, 8 cc diazepam and 21 cc ketamine. The patient was intubated, hoisted and placed in right lateral recumbancy on a portable bed. Once transported into the MRI, she was positioned with her right hind foot in the magnet. Test pilots were run to confirm proper positioning, and scanning of the foot began immediately. Once the patient was

Photo courtesy of The Wisconsin Equine Clinic and Hospital

Sally Schwartz, CVT and Nicole Howie, CVT

Monitoring during anesthesia at The Wisconsin Equine Clinic and Hospital.

properly aligned, the anesthesia technician was able to set up the anesthetic equipment and begin IV fluids. The patient was started on 5% isoflourane. Due to the magnet, the only monitoring equipment available to the anesthesia technician was a stethoscope at this point. The patient’s vitals were as follows: respiratory rate was 4 breaths/min, heart rate was 40 beats/min, mucus membranes were pink, capillary refill time was 2 sec, and the eye was palpebral. A dobutamine drip was started (2 cc dobutamine/250 mL 5% dextrose) as a provision, as the horse’s pressures were unknown at this time.

ModernEquineVet.com | Issue 3/2014

15

technician update The horse’s MAP became low, at 58 mgHg, despite the dobutamine drip. In response, she decreased the patient’s isoflourine from 5% to 4%. The primary veterinarian on the case was notified of the low pressures, and he advised to give 0.5 mL phenylepherine IV to increase the blood pressure. At this point, the scanning of the patient’s foot had been completed.

The magnet and coil were repositioned to the pastern, and piloting began.

The phenylepherine only maintained the patient’s pressures for the next 13 minutes, after which point they dropped again. A second dose of 0.5 mL phenylepherine was given and a bolus of 1 L of hypertonic saline was started. This time the pressures remained adequate for only 15 minutes.

At this point the total anesthesia time was 1 hour and 10 minutes, and the pastern scanning was approximately 50% complete. The case doctor directed to begin 23% calcium gluconate solution at a fast drip with the LRS and dobutamine to maintain adequate pressures for a longer period. This combination maintained the patient’s blood pressure around 85 mgHg. At this point the pastern scanning had been completed and the patient had been under general anesthesia for just over 2 hours. It was decided to end the scanning and the patient was transported to the recovery stall to wake-­up.

Her recovery was routine and uneventful.

Follow up

The patient’s MRI images revealed distinct inflammation of the lateral wing of the coffin bone and a dramatic inflammatory response in the pastern joint region along with significant bone edema of the medial condyle. To treat this condition the patient was injected with IRAP, IV tiludronic acid (Tildren, Ceva) was given, shockwave was performed and polysulfated glycosaminoglycan (Adequan IM, Luit-

pold Animal Health) was recommended. The patient was confined to strict stall rest and reevaluated 30 days from the date of the MRI. At 30 day recheck, the patient was found to have drastic improvement in swelling through the pastern region and the lameness had improved to a 1.5/5.

Shockwave therapy was performed and the IRAP injection was repeated. The client was advised to continue stall resting the patient for an additional 60 days at which point a second recheck should be performed, which would be mid-­July.

Although it was initially recommended to scan the fetlock also, the MRI technician, veterinarian, and anesthetic technician consulted regarding the horse’s state of anesthesia and the need to obtain further images. Although the horse was maintaining her pressures, keeping her under anesthesia for another hour to obtain fetlock images was not worth the risk of complications. The foot and pastern images were assessed throughout the scanning by the MRI technician and the veterinarian, and it was felt that several significant injuries were observed, which were consistent with the patient’s lameness and blocking history. The decision to not scan the fetlock was jointly made. All parties felt that it was appropriate to end the scanning.

In a situation such as this, no matter how advanced the imaging technology is, the horse still determines how much of that technology we can use.

This case emphasized the irony between using the most basic anesthetic monitoring tools (the technician and the stethoscope) and obtaining some of the most advanced diagnostic imaging through the use of the MRI. Both the anesthetic technician, as well as the MRI technician, were required to assess the situation and tailor their duties to meet what was most important, the welfare of the horse.

MeV

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news notes

Animal Health Trust launches large-scale, two-year vaccine trial against equine grass sickness The Animal Health Trust (AHT) launched a nationwide placebo-controlled trial of a vaccine for the prevention of equine grass sickness, a frequently fatal disease affecting horses.

Following the successful completion of a small pilot study in 2013, the AHT will begin recruiting horses for the national trial, which will be conducted by the AHT and the Universities of Edinburgh, Liverpool and Surrey.

EGS is a debilitating and often fatal disease affecting horses, ponies and donkeys that occurs predominantly in northern Europe. Britain has the highest incidence worldwide. Almost all cases of EGS occur in grazing horses, and it is thought they are exposed to some form of noxious agent in the soil ingested as a contaminant of grass.

There is growing scientific evidence to suggest that EGS may be caused by the bacterium Clostridium botulinum type C, which is common in soil and is capable of producing a range of toxins, including neurotoxins to which horses are particularly sensitive.

The theory is that EGS is a toxico-infectious form of botulism caused by C. botulinum type C, with the disease occurring when a combination of risk factors triggers the production of toxins within the horse’s intestinal tract. A field vaccine trial is the only way

Adequan now available Polysulfated glycosaminoglycan (Adequan IM and Adequan IA, Luitpold Animal Health) is available in both the 5 mL single dose and 50 mL multidose vials for use in horses.

Luitpold apologized for an inconvenience caused by the past disruption in supply and is working to ensure continued market demand.

Veterinarians who need to order Adequan or is having difficulty obtaining the product, can call 800-458-0163.

Luitpold has established a dedicated website for more information www.adequan.com.

Adequan IM and Adequan IA are the only polysulfated glycosaminoglycan approved by the FDA for the treatment of noninfectious degenerative and/or traumatic joint dysfunction and associated lameness in horses.

MeV

to evaluate whether a vaccine could be effective in reducing the risk of EGS. The trial will follow 1,100 horses and ponies for two years. Only healthy horses and ponies with a valid passport kept on premises with a history of EGS cases in the previous two years will be eligible for enrollement.

MeV For information:www.equinegrasssickness.co.uk.

Two horses with equine grass sickness. Thanks to Prof. Chris Proudman of the University of Surrey for the picture on the left and the Animal Health Trust for the picture on the right.

AVMA admits veterinary acupuncture academy into House of Delegates The American Academy of Veterinary Acupuncture (AAVA) was recently admitted into the American Veterinary Medical Association House of Delegates (AVMAHOD) as a constituent allied veterinary organization.

The AVMA-HOD is comprised of AVMA members from 70 state, territorial and allied veterinary medical groups. Association policies that affect the practice of veterinary medicine are set by HOD delegates and alternative delegates from each organization.

“I am pleased to welcome the AAVA and its members into the AVMA House of Delegates,” says Clark K. Fobian, DVM, president of the AVMA. “Admitting the AAVA into the house will foster greater communication between this organization’s membership and the rest of the veterinary community.”

The AAVA has more than 900 members, and its mission statement is: “To improve animal health care by the advancement of veterinary acupuncture, Traditional Chinese Veterinary Medicine and Traditional Asian Medicine through education, research and leadership.”

Veterinary acupuncture is a relatively young but fast growing practice area of veterinary medicine. Veterinarians in the United States began adopting veterinary acupuncture in the 1970s. Since the mid-1990s, however, acupuncture training programs have experienced increased enrollments every year, according to the AAVA. MeV ModernEquineVet.com | Issue 3/2014

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