The Modern Equine Vet February 2019

The Modern

Equine Vet www.modernequinevet.com

Vol 9 Issue 2 2019

Triaging Fractures What you do could save a horse's life

Managing Common Dental Overgrowths Image-Guided Sinus Surgery Technician Update: Circulatory Compromise from Bandage Constriction

TABLE OF CONTENTS

COVER STORY

8 Triaging the Simple Fracture Cover photo: Shutterstock/ChrisVanLennepPhoto

SURGERY

Human Image-Guided Sinus Procedure Performed on Horse.............................................................................. 4 DENTISTRY

Managing Common Dental Overgrowths...................................11 TECHNICIAN UPDATE

Bandage Constriction Causes Circulatory Compromise of the Bilateral Forelimb.....................................13 NEWS

A Zebra’s Stripes May Deter Horseflies from Landing on Them, According to a New Study...........................12 Obese Pony's Microbiome Differs from Aged Pony's...............12 ADVERTISERS Standlee Premium Western Forage.........................3 American Regent Animal Health.............................5

Merck Animal Health..................................................7 AAEVT............................................................................17

The Modern

Equine Vet SALES: Matthew Todd • ModernEquineVet@gmail.com Lillie Collett • ModernEquineVetSales@gmail.com EDITOR: Marie Rosenthal • mrosenthal@percybo.com ART DIRECTOR: Jennifer Barlow • jbarlow@percybo.com CONTRIBUTING WRITERS: Paul Basillo • Adam Marcus COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers PERCYBO media  publishing

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SURGERY

Honesto's radiograph revealed a large tumor in his sinus cavity.

Human Image-Guided Sinus Procedure

Photos courtesy of UC Davis

PERFORMED ON HORSE

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University of California Davis equine surgeons worked with a human otolaryngologist to perform an image-guided sinus procedure on a horse.

Honesto, a 6-year-old LusitanoArabian cross gelding, presented with a generalized swelling and enlargement of the bone and soft tissues below his right eye.

Radiographs and a CT scan taken at the UC Davis veterinary hospital revealed a massive sinus osteoma that was encroaching on his eye socket and blocking the right nasal cavity and numerous sinuses,

Issue 2/2019 | ModernEquineVet.com

including the frontal sinus, directly in front of the brain.

To prevent the tumor from growing larger and injuring the eye and brain, a very delicate surgery was needed.

Normally, removal of a tumor like Honesto’s is achieved by making a large incision in the area in order to burr away the rock-hard tumor with a rotary tool and chisel. Unfortunately, there is no way for surgeons to determine how close they are getting to critical areas such as the eye or the brain.

Larry D. Galuppo, DVM, chief

of the Equine Surgery and Lameness Service, explained these risks to Honesto’s owner, Angela Langen.

As Ms. Langen decided how to proceed, she discussed the case with her close friend, George Domb, MD, an otolaryngologist, who specializes in human sinus surgery. Dr. Domb suggested a technique used in human medicine that has made extensive sinus surgeries safe.

Using an image-guided navigation system, surgeons could operate on Honesto’s tumor while identifying the precise position of their surgical instruments on a CT scan at every moment. This procedure would allow the surgeons to avoid inadvertent entry into the brain or eye socket.

Dr. Galuppo agreed to work with Dr. Domb to attempt this first-ever approach to a tumor removal in an equine sinus.

Drs. Galuppo and Domb undertook the challenging procedure. Assisting them in surgery was secondyear equine surgery resident Dr. Tom Cullen, who helped with the

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Ask your veterinarian if Adequan® i.m. is the right choice for your horse. Learn more at adequan.com.

BRIEF SUMMARY: Prior to use please consult the product insert, a summary of which follows: CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. INDICATIONS: Adequan® i.m. is recommended for the intramuscular treatment of non-infectious degenerative and/or traumatic joint dysfunction and associated lameness of the carpal and hock joints in horses. CONTRAINDICATIONS: There are no known contraindications to the use of intramuscular Polysulfated Glycosaminoglycan. WARNINGS: Do not use in horses intended for human consumption. Not for use in humans. Keep this and all medications out of the reach of children. PRECAUTIONS: The safe use of Adequan® i.m. in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. For customer care, or to obtain product information, visit www.adequan.com.

To report an adverse event please contact American Regent, Inc. at (800) 734-9236 or email pv@americanregent.com.

Please see Full Prescribing Information at www.adequan.com.

1 Adequan® i.m. Package Insert, Rev 1/19.

2 Burba DJ, Collier MA, DeBault LE, Hanson-Painton O, Thompson HC, Holder CL: In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondral defect model. J Equine Vet Sci 1993; 13: 696-703.

Adequan and the Horse Head design are registered trademarks of American Regent, Inc. © 2019, American Regent, Inc. PP-AI-US-0214 02/2019

SURGERY

CT scan showing the massive tumor in Honesto's sinus

Home care consisted of daily flushes of Honesto’s sinuses through a drainage tube that the surgical team left in place for this purpose.

Honesto recovering after successful surgery to remove a sinus tumor.

entire case management.

Honesto recovered well from anesthesia and was able to return home two days after surgery.

“We were pleased to see that the procedure worked well,” said Dr. Galuppo. “We were able to remove a substantial portion of the tumor in order to open the sinus cavity and take any pressure off Honesto’s eye socket and brain. He’s one tough horse.”

Home care for Langen consisted of daily flushes of Honesto’s sinuses through a drainage tube that the surgical team left in place for this purpose.

At Honesto’s 1-week recheck appointment, Dr. Galuppo noted great progress and removed the si6

Area where Honesto's sinus tumor was located.

Issue 2/2019 | ModernEquineVet.com

Honesto on the road to recovery after the drainage tube was released.

The image-guided navigation enabled the surgeons to identify the precise position of instruments during the procedure. nus irrigation tube. At his 2-week recheck, the skin staples were removed.

“Dr. Galuppo said I could ride

Owner Angela Langen is back to riding Honesto after UC Davis equine surgeons teamed with a physician to remove a sinus tumor.

him at a walk,” Ms. Langen noted.

“He had so much energy at his first trail ride, it was amazing. Dr. Domb also told me that he was happy with the results and how excited he was to work with the veterinarians.”

“This was the first time I’ve ever seen surgery on a horse, much less participated,” said Dr. Domb. “It was amazing how the anesthesia team took care of Honesto, and collaborating with the entire veterinary team at UC Davis was a wonderful experience. Dr. Galuppo and everyone on the equine surgery team made the whole procedure flawless.”

Drs. Domb and Dr. Galuppo plan to have further discussions about translating human sinus treatments to veterinary medicine.

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From the broodmare to the performance horse, properly managing your mare’s hormones is critical. Rely on the product that’s trusted most.

• More than 30 years of practical use in the field by veterinarians 1 • More than 200 clinical trials to determine efficacy, duration and safety1 • More than 20 million doses sold to veterinarians, trainers and horse owners 1 Now that’s trusted.

Ask your veterinarian for Regu-Mate®. Visit us online at merck-animal-health-equine.com to learn more about Merck Animal Health and the equine products and programs that help keep horses healthy.

Talk to your veterinarian about proper use and safe handling of Regu-Mate®. Avoid skin contact. Always wear protective gloves when administering Regu-Mate®. This product is contraindicated for use in mares with a previous or current history of uterine inflammation. Pregnant women, or women who suspect they are pregnant, should not handle this product. For complete product information, see accompanying product insert.

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ORTHOPEDIC

Regu-Mate® (altrenogest) Solution 0.22% (2.2 mg/mL) CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian.

DESCRIPTION: Regu-Mate® (altrenogest) Solution 0.22% contains the active synthetic progestin, altrenogest. The chemical name is 17α-allyl-17ß-hydroxyestra-4,9,11-trien-3-one.

The CAS Registry Number is 850-52-2. The chemical structure is: Each mL of Regu-Mate® (altrenogest) Solution 0.22% contains 2.2 mg of altrenogest in an oil solution.

ACTIONS: Regu-Mate® (altrenogest) Solution 0.22% produces a progestational effect in mares.

INDICATIONS: Regu-Mate® (altrenogest) Solution 0.22% is indicated to suppress estrus in mares. Suppression of estrus allows for a predictable occurrence of estrus following drug withdrawal. This facilitates the attainment of regular cyclicity during the transition from winter anestrus to the physiological breeding season. Suppression of estrus will also facilitate management of prolonged estrus conditions. Suppression of estrus may be used to facilitate scheduled breeding during the physiological breeding season.

CONTRAINDICATIONS: Regu-Mate® (altrenogest) Solution 0.22% is contraindicated for use in mares having a previous or current history of uterine inflammation (i.e., acute, subacute, or chronic endometritis). Natural or synthetic gestagen therapy may exacerbate existing low-grade or “smoldering” uterine inflammation into a fulminating uterine infection in some instances.

PRECAUTIONS: Various synthetic progestins, including altrenogest, when administered to rats during the embryogenic stage of pregnancy at doses manyfold greater than the recommended equine dose caused fetal anomalies, specifically masculinization of the female genitalia.

DOSAGE AND ADMINISTRATION: While wearing protective gloves, remove shipping cap and seal; replace with enclosed plastic dispensing cap. Remove cover from bottle dispensing tip and connect luer lock syringe (without needle). Draw out appropriate volume of Regu-Mate solution.

(Note: Do not remove syringe while bottle is inverted as spillage may result.) Detach syringe and administer solution orally at the rate of 1 mL per 110 pounds body weight (0.044 mg/kg) once daily for 15 consecutive days. Administer solution directly on the base of the mare’s tongue or on the mare’s usual grain ration. Replace cover on bottle dispensing tip to prevent leakage.

Excessive use of a syringe may cause the syringe to stick; therefore, replace syringe as necessary.

SPECIFIC USES FOR REGU-MATE® (altrenogest) SOLUTION 0.22%: SUPPRESSION OF ESTRUS TO: 1. Facilitate attainment of regular cycles during the transition period from winter anestrus to the physiological breeding season. To facilitate attainment of regular cycles during the transition phase, mares should be examined to determine the degree of ovarian activity. Estrus in mares with inactive ovaries (no follicles greater than 20 mm in diameter) will be suppressed but these mares may not begin regular cycles following treatment. However, mares with active ovaries (follicles greater than 20 mm in diameter) frequently respond with regular post-treatment estrus cycles.

2. Facilitate management of the mare exhibiting prolonged DOSAGE CHART: estrus during the transition period. Estrus will be suppressed in mares exhibiting prolonged behavioral estrus either early Approximate Weight Dose or late during the transition period. Again, the posttreatment in Pounds in mL response depends on the level of ovarian activity. The 770 7 mares with greater ovarian activity initiate regular cycles 880 8 and conceive sooner than the inactive mares. Regu-Mate® 990 9 (altrenogest) Solution 0.22% may be administered early in 1100 10 the transition period to suppress estrus in mares with inactive 1210 11 ovaries to aid in the management of these mares or to mares 1320 12 later in the transition period with active ovaries to prepare and schedule the mare for breeding.

3. Permit scheduled breeding of mares during the physiological breeding season. To permit scheduled breeding, mares which are regularly cycling or which have active ovarian function should be given Regu-Mate® (altrenogest) Solution 0.22% daily for 15 consecutive days beginning 20 days before the date of the planned estrus. Ovulation will occur 5 to 7 days following the onset of estrus as expected for nontreated mares. Breeding should follow usual procedures for mares in estrus. Mares may be regulated and scheduled either individually or in groups.

ADDITIONAL INFORMATION: A 3-year well controlled reproductive safety study was conducted in 27 pregnant mares, and compared with 24 untreated control mares. Treated mares received 2 mL Regu-Mate® (altrenogest) Solution 0.22% /110 lb body weight (2x dosage recommended for estrus suppression) from day 20 to day 325 of gestation. This study provided the following data: 1. In filly offspring (all ages) of treated mares, clitoral size was increased.

2. Filly offspring from treated mares had shorter interval from Feb. 1 to first ovulation than fillies from their untreated mare counterparts.

3. There were no significant differences in reproductive performance between treated and untreated animals (mares & their respective offspring) measuring the following parameters: • •

• • • • • • •

interval from Feb. 1 to first ovulation, in mares only. mean interovulatory interval from first to second cycle and second to third cycle, mares only. follicle size, mares only. at 50 days gestation, pregnancy rate in treated mares was 81.8% (9/11) and untreated mares was 100% (4/4). after 3 cycles, 11/12 treated mares were pregnant (91.7%) and 4/4 untreated mares were pregnant (100%). colt offspring of treated and control mares reached puberty at approximately the same age (82 & 84 weeks respectively). stallion offspring from treated and control mares showed no differences in seminal volume, spermatozoal concentration, spermatozoal motility, and total sperm per ejaculate. stallion offspring from treated and control mares showed no difference in sexual behavior. testicular characteristics (scrotal width, testis weight, parenchymal weight, epididymal weight and height, testicular height, width & length) were the same between stallion offspring of treated and control mares.

REFERENCES: Shoemaker, C.F., E.L. Squires, and R.K. Shideler. 1989.Safety of Altrenogest in Pregnant Mares and on Health and Development of Offspring. Eq. Vet. Sci. (9); No. 2: 69-72.

Squires, E.L., R.K. Shideler, and A.O. McKinnon. 1989.Reproductive Performance of Offspring from Mares Administered Altrenogest During Gestation. Eq. Vet. Sci. (9); No. 2: 73-76.

WARNING: Do not use in horses intended for food.

HUMAN WARNINGS: Skin contact must be avoided as Regu-Mate® (altrenogest) Solution 0.22% is readily absorbed through unbroken skin. Protective gloves must be worn by all persons handling this product. Pregnant women or women who suspect they are pregnant should not handle Regu-Mate® (altrenogest) Solution 0.22%. Women of child bearing age should exercise extreme caution when handling this product. Accidental absorption could lead to a disruption of the menstrual cycle or prolongation of pregnancy. Direct contact with the skin should therefore be avoided. Accidental spillage on the skin should be washed off immediately with soap and water.

INFORMATION FOR HANDLERS: WARNING: Regu-Mate® (altrenogest) Solution 0.22% is readily absorbed by the skin. Skin contact must be avoided; protective gloves must be worn when handling this product.

Effects of Overexposure: There has been no human use of this specific product. The information contained in this section is extrapolated from data available on other products of the same pharmacological class that have been used in humans. Effects anticipated are due to the progestational activity of altrenogest. Acute effects after a single exposure are possible; however, continued daily exposure has the potential for more untoward effects such as disruption of the menstrual cycle, uterine or abdominal cramping, increased or decreased uterine bleeding, prolongation of pregnancy and headaches. The oil base may also cause complications if swallowed. In addition, the list of people who should not handle this product (see below) is based upon the known effects of progestins used in humans on a chronic basis.

PEOPLE WHO SHOULD NOT HANDLE THIS PRODUCT. 1.

2.

3.

4.

5.

6.

7.

8.

Women who are or suspect they are pregnant.

Anyone with thrombophlebitis or thromboembolic disorders or with a history of these events.

Anyone with cerebral-vascular or coronary artery disease.

Women with known or suspected carcinoma of the breast.

People with known or suspected estrogen-dependent neoplasia.

Women with undiagnosed vaginal bleeding.

People with benign or malignant tumors which developed during the use of oral contraceptives or other estrogen-containing products.

Anyone with liver dysfunction or disease.

ACCIDENTAL EXPOSURE: Altrenogest is readily absorbed from contact with the skin. In addition, this oil based product can penetrate porous gloves. Altrenogest should not penetrate intact rubber or impervious gloves; however, if there is leakage (i.e., pinhole, spillage, etc.), the contaminated area covered by such occlusive materials may have increased absorption. The following measures are recommended in case of accidental exposure.

Skin Exposure: Wash immediately with soap and water.

Eye Exposure: Immediately flush with plenty of water for 15 minutes. Get medical attention.

If Swallowed: Do not induce vomiting. Regu-Mate® (altrenogest) Solution 0.22% contains an oil. Call a physician. Vomiting should be supervised by a physician because of possible pulmonary damage via aspiration of the oil base. If possible, bring the container and labeling to the physician.

CAUTION: For oral use in horses only. Keep this and all medication out of the reach of children.

Store at or below 25°C (77°F).

NADA# 131-310, Approved by FDA. HOW SUPPLIED: Regu-Mate® (altrenogest) Solution 0.22% (2.2 mg/mL).

Each mL contains 2.2 mg altrenogest in an oil solution.

Available in 1000 mL plastic bottles.

TRIAGING the Simple Fracture B y

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When a horse suffers a fracture on the track or on the farm, the best way to improve its prognosis is to stabilize the injury to prepare it for transport to an orthopedic surgeon, according to Anton Fürst, DVM, DECVS, equine hospital, Vetsuisse faculty, University of Zurich, Switzerland.

“Temporary immobilization of the fractured limb is extremely important to improve its chances for survival,” Dr. Fürst said at the BEVA Congress 2018 in Birmingham, United Kingdom. “If the horse is not treated properly in the beginning, it worsens the prognosis,” The veterinarian wants to relieve the pain, establish a diagnosis if possible, facilitate the repair and transport the horse as efficiently and quickly as possible.

“The prognosis and the triage depend on the fracture,” he explained, “but fissures of the long bone and cannon bone, if stabilized correctly can have a good prognosis. The less complicated the fracture, the better the animal’s recovery

* US Patents 3,453,267; 3,478,067; 3,484,462 Manufactured by: DPT Laboratories, San Antonio, TX 78215 Distributed by: Intervet Inc., Millsboro, DE 19966

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chances are. Stress fractures and simple fractures have a better chance than a shattered bone or open fracture.

“Triage involves sedation, wound management, prophylaxis against infection, stabilization of the leg, proper analgesia, careful and safe rescue and transportation,” he said.

“This is the concept you need in your head whenever you are faced with a seriously injured horse or a horse with a fractured leg,” he said.

He tends to use xylazine or detomidine (5 to 10 mg/500 kg horse.) and butorphanol (10 mg/500 kg horse.) to achieve good sedation. If the animal needs to be transported for a long period, he will add acepromazine.

“Think about and analgesia. It’s very important in most cases,” he said. “Over the last few years, veterinarians have come to realize that the horse does much better if it gets the correct analgesia.”

Nonsteroidal anti-inflammatory drugs are the foundation of equine pain medicine and are important in this case, and he

Shutterstock/ChrisVanLennepPhoto

WHICH MARES WILL RESPOND TO REGU-MATE® (altrenogest) SOLUTION 0.22%: Extensive clinical trials have demonstrated that estrus will be suppressed in approximately 95% of the mares within three days; however, the post-treatment response depended on the level of ovarian activity when treatment was initiated. Estrus in mares exhibiting regular estrus cycles during the breeding season will be suppressed during treatment; these mares return to estrus four to five days following treatment and continue to cycle normally. Mares in winter anestrus with small follicles continued in anestrus and failed to exhibit normal estrus following withdrawal.

Response in mares in the transition phase between winter anestrus and the summer breeding season depended on the degree of follicular activity. Mares with inactive ovaries and small follicles failed to respond with normal cycles post-treatment, whereas a higher proportion of mares with ovarian follicles 20 mm or greater in diameter exhibited normal estrus cycles posttreatment. Regu-Mate® (altrenogest) Solution 0.22% was very effective for suppressing the prolonged estrus behavior frequently observed in mares during the transition period (February, March and April). In addition, a high proportion of these mares responded with regular estrus cycles post-treatment.

one leg is absolutely unstable, they always try to get these limbs stable and as soon as you have stabilized the leg with a cast or splint, they are much quieter,” he said.

Try to prevent soft tissue damage and to prevent perforation of the skin—the broken bone can be sharp—add 1 cm of padding to

protect the soft tissue.

While there are many different materials to immobilize the leg, Dr. Fürst prefers PVC pipes like the ones used by plumbers.

They are not too expensive and are available in different sizes. They are fairly easy to cut, and can be used for hind legs, too, which are Triage involves sedation, wound management, prophylaxis against infection, stabilizing the leg, proper anesthesia and careful and safe rescue and transportation.

Image courtesy of Dr. Anton Fürst

adds them to the analgesia to provide pain relief.

He suggested managing any wounds by clipping the hair, cleaning them with a mild disinfectant and applying hydrogel on sterile dressing before stabilizing the fracture. Providing 30,000 IU/ Kg IV penicillin and 7–10 mg/kg IV gentamicin are probably warranted for large wounds or open fractures.

Dr. Fürst also recommended IV fluid therapy. This is especially important if the animal has a long ride to a specialist clinic. “Horses always profit when they have IV fluid,” he said.

Remember the idea is triage— a temporary fix, not a cast. “A real cast will stay there for weeks, but this stabilization is only there for transportation,” he said.

A horse always wants to put its four legs to the ground. “So, when

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ORTHOPEDIC

Stabilizing an Equine Fracture PVC SPLINT SIZES • PVC pipes are cut into half or third diameter DIFFERENT LENGTHS 40 cm: hoof to the proximal metacarpus, caudal 60 cm: hoof to the caudal calcaneus, caudal 55 cm: fetlock to the elbow, caudal 70 cm: fetlock to the stifle, angled, cranial 1 m: hoof to the elbow, caudal 1 m: hoof to the stifle, angled cranial more difficult to stabilize.

“In my eyes, they are an excellent splint and are very stable for temporary immobilization of the leg,” he said. “The fixation of the fractured limb in an anatomically

normal position is the most important aspect of the initial treatment.”

The goals of stabilization are to reduce stress and anxiety by providing some limited weight bearing, alleviate pain and prevent complications by reducing trauma to the bone and soft tissue.

The joint above and below the fractured bone should be immobilized, and include the hoof.

They start with bandaging material that is similar to the Robert Jones bandage and make sure there is 1 cm of padding below the splint. The leg should be stabilized from the hoof up to the elbow joint or whatever joint is above the damaged bone. Then they splint with the PVC pile and keep it all in place with tape.

“That is what we use for all types of fractures when we have

injured the bone in different locations,” Dr. Fürst said. The splint should not end at the mid diaphysis, because that is a weak point, according to Dr. Fürst.

Some animals might require a cast for transportation, especially if the fracture is more complex.

That animal should be harnessed for transport.

However, if the horse is lame from a suspected fissure, but there is no way to determine which bone has fractured, don’t cast it, he said. “Don’t put the cast on if you don’t know where you have your damaged bone because the cast and splints make the leg heavier, and they can put more weight to the already damaged bone.

Don’t use immobilization if you have suspicion but you are not able to say if it is a humorous fracture or a P1 fracture.”

MeV

Images 1A and B are examples of improper triage.

1A

1B

2A

2B

Images courtesy of Anton Fürst

Images 2A and B are examples of the correct first aid treatment.

Transporting a horse that is properly triaged.

For more information: Wright IM. Racecourse fracture management. Parts 1, 2 and 3. Equine Vet Educ. 2016 Mar 7. (Epub ahead of print). https://onlinelibrary.wiley.com/doi/abs/10.1111/eve.12561 10

Issue 2/2019 | ModernEquineVet.com

DENTISTRY

Managing Common

Dental Overgrowths B

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Managing common dental

overgrowths is not just a matter of grinding down the teeth, according to Nicole du Toit, BVSc, CertEP, MSc, PhD, DEVDC(equine), DVDC (equine), MRCVS, an associate at the Equine Dental Clinic, Dorset, United Kingdom.

“We just want to take off those sharp points that could be potentially impinging on the cheeks or impinging on the tongue,” she said.

The goal is to make the horse comfortable and to restore normal masticatory function so the horse can chew properly.

How much should be removed depends on the overgrowth. Care needs to be taken when rasping overgrowths as the depth of secondary dentine protecting the live pulp horns varies greatly among horses—there may be as little as 2 mm between the occlusal surface and the live pulp. While in other teeth or pulp horns, there may be as much as 15 mm of secondary dentine before the live pulp is reached. Every time the teeth are rasped, they may expose sensitive dentine, so care needs to be taken when rasping teeth. “There is no way to know when you are looking at a tooth how much secondary dentine you have,” she said.

“Horses are individuals. Some people really go on about rasping to re-establish the normal occlusive angles, but I think you need to look at that horse and determine what is best for that individual horse. Are these physiological or pathological

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differences? Is this normal for this horse or not,” she said.

Once the primary dental pathology is managed, try to re-establish the normal occlusal angle and wear pattern for that horse.

Normal dental overgrowths are often secondary problems. If the primary pathology is solved, the overgrowths may take care of themselves, often only needing initial correction, according to Dr. du Toit, who spoke at the BEVA Congress.

With the majority of small hooks involving minimal enamel and dentine, they can just be rounded off.

“Just remember that you are potentially exposing a little bit of sensitive occlusive dentine even if you are not going into the pulp but you can still be making that horse a little bit sensitive so once again take that into consideration,” she said.

Exaggerated transverse ridges may be rasped if excessive and interfering with normal mastication.

“When we are dealing with much larger overgrowths, we need to do some staged rasping. When there are particularly large overgrowths that are inhibiting a horse’s normal masticatory action, the temptation is there to reduce the overgrowth as quickly as possible, but you have to be careful that you do it in stages.

“Most of the time you can take down 3 or 4 mm, but it is really important to educate the owner that it will take three or four treatments before they will be level with the other teeth,” she suggested.

Overgrowths are quite common,

M

S

During Rasping • Stop to rinse mouth • Clean burr of tooth dust at regular intervals (steel brush) • Maximize cutting\minimize heat production • Stop to examine the occlusal surface

Follow up • Schedule a dental re-examination • Routine intervals (6 to 12 months) with smaller overgrowths • Shorter follow up (3 to 4 months) with larger overgrowths • Initial super eruption of opposing tooth after extraction — shorter routine intervals. occurring in about 27% of donkeys and ponies and 23% of horses.

There is often a sense that sharp enamel points are more pronounced in domesticated horses fed concentrate diets because of less sideways masticatory action, but Dr. du Toit thinks the development of sharp enamel points is part of the normal dental physiology of the horse.

“When you look at horses that are semi-feral or horses that live in more natural type of environment, you will find they still develop sharp enamel points, so that is not really a result of domestication,” she explained. “This is something that is natural and has been there for a long time.”

Remember that the teeth are continually erupting, and overgrowths may develop again, so regular follow up is important.

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NEWS NOTES

Zebra’s Stripes May Prevent Horsefly Bites A zebra's stripes might reduce the likelihood of being bitten by predatory flies, a new study found.

In this study, Tim Caro, PhD, of the University of California Davis, Martin How, PhD, of the University of Bristol, in the United Kingdom, and their colleagues compared the behavior of horseflies as they attempted

to prey on zebras and uniformly colored horses held in similar enclosures. Flies circled and touched the horses and zebras at similar rates, but actually landed on zebras less than 25% as often.

When horses wore a striped, black-and-white coat, flies landed far less often on the striped coat but just as often on the uncovered head.

Although the flies decelerated prior to landing on the horses, they approached zebras at a faster clip and failed to slow down as they closed the distance, often bumping into the zebra before flying away again.

Additionally, the zebras were at greater pains to keep flies off through tail swishing and running away.

Taken together, these results indicate that stripes do not deter flies from approaching zebras, but do prevent effective landing, and thus, reduce the number of flies successfully feeding. This finding provides further support for the hypothesis that the evolutionary benefit of zebra stripes is to reduce biting by predatory flies.

“We observed and filmed the behavior of horseflies near captive zebras and horses and found that flies failed to decelerate close to stripes, preventing controlled landings. Combined with zebras' anti-parasite behavior, few flies landed successfully or probed their hosts for blood,” the researchers wrote.

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For more information: Caro T, Argueta Y, Briolat ES, et al. Benefits of zebra stripes: Behaviour of tabanid flies around zebras and horses. PLOS ONE 2019; 14 (2): e0210831 DOI: 10.1371/journal.pone.02108312019; 14 (2): e0210831 DOI: 10.1371/journal.pone.0210831

Obesity May Affect Pony's Gut More Than Aging A new study suggests that obesity in ponies may have a greater effect on gut microbes than aging.

Fecal samples from obese ponies, aged ponies and ponies that were neither obese nor aged that were fed the same hay diet were analyzed to assess differences in their gut microbes. The diversity significantly increased in obese ponies and tended to increase in aged ponies—the opposite of what has been seen in similarly aged horses.

Dr. Philippa K. Morrison and her colleagues have published work showing a reduction in the microbiome diversity in elderly horses, regardless of diet.

This could mean that age-associated changes in the microbiome occur at a later chronological age in ponies than horses, according to Dr. Morrison, of Scotland’s Rural College, Craibstone Estate, Aberdeen, United Kingdom. Although each group of po12

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nies could be differentiated from each other across the whole study, it was not possible to consistently predict whether ponies belonged to the aged, obese or control group by looking at the fecal microbes alone.

In people, a reduction in gut diversity has been linked to both aging and obesity.

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For more information: Morrison PK , Newbold CJ , Jones E , et al. The equine gastrointestinal microbiome: Impacts of age and obesity.

Front Microbiol. 2018 (Epub Dec 7). https://pure.aber. ac.uk/portal/files/28528119/fmicb_09_03017.pdf The study was done in collaboration between SPILLERS and the Waltham Equine Studies Group.

TECHNICIAN UPDATE

Circulatory Compromise as a Result of Bandage Constriction on the Bilateral Forelimb The “Bandage Bow” You Don’t Want to Know

By Jessica Cook, CVT A steeplechase horse that ran a race of 2 1/16th miles over national fences and placed second while wearing rundowns on his front limbs presented for swelling in the palmar metacarpal soft tissue region.

Apparently post-race isolated swelling without significant sensitivity was noted in the palmar metacarpal region and “bandage bows” of both forelimbs were suspected. He was treated at the farm with cold and antiinflammatory therapy, including cold hosing and topical application of diclofenac ointment and prophylactic antibiotics.

When he was presented to us on the third day, swelling had become more diffuse with increased sensitivity.

Initial ultrasonography showed subcutaneous swelling in the palmar metacarpal aspect of both forelimbs.

As the case progressed, the patient’s serum amyloid A (SAA) became elevated, and the swelling persisted.

By the eighth day, the central aspect of the palmar metacarpal soft tissues began to show evidence of necrosis.

Initially, ultrasound imaging continued to show no tendon involvement, but as necrosis progressed it became evident that the superficial digital flexor tendons were involved in both forelimbs. The necrotic tissue then sloughed, surgical debridement was required and intense therapy was continued until resolution.

inflammatory protocols were implemented. The patient was cold-hosed twice daily and bandaged using a topical diclofenac ointment.

The window of concern in these severe cases of post constriction is 7–10 days from injury, requiring intense observation. Upon each bandage change, careful evaluation of the skin and sensitivity of the area can indicate severity of injury. In this case it was 6 days from injury that the SAA had increased to 163. While this is not significantly high, it was an increase from the original test.

The SAA test is highly sensitive and can change even hour-to-hour. Therefore it was repeated at multiple visits to monitor for increases.

It was recommended that the patient be sent to a facility with a cold saltwater spa for aggressive treatment.

Nine days from the race, the central palmar metacarpal region began to lose its hair and the skin’s appearance changed, becoming much paler than the surrounding tissue (Figure 1). Ultrasonography was repeated and continued to show subcutaneous edema, but tendon structures appeared to be within normal limits. More necrosis was apparent with continued bandage changes every 2–3 days always under veterinary supervision (Figure 2). Serous drainage had started, as well as peeling around edges of what-would-become wounds. The

The swelling was generalized in the entire palmar metacarpal region. Once a specific profile was noted it became apparent that the constriction of the bandages were not uniform on either limb and the central palmar metacarpal soft tissues were most affected. At the primary appointment, an SAA test had a reading of 1, implying there was no systemic infection present. The SAA was tested stall-side with a Stable Lab testing kit and reader, measuring the level of SAA—which is an indicator of inflammation and therefore directly correlates with infection. An ultrasound of both forelimbs displayed significant subcutaneous swelling, but no structural involvement, most specifically, the superficial digital flexor tendon was unaffected. Acute cold/anti-

All photos courtesy of Jessica Cook

Clinical Exam and Diagnostics

FIGURE 1.

FIGURE 2.

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TECHNICIAN UPDATE

FIGURE 3.

FIGURE 4.

SAA had increased again to 253. The patient continued to remain sound and fully weight-bearing in both forelimbs. Signs will vary in timing and severity depending on the amount of circulatory compromise.

On approximately day 15 significant drainage with odor was evident in both limbs. There was a proliferation of granulation tissue of both wounds (Figure 3).

Although the edges had begun contracting, 21 days into treatment he was noted to be variably lame, 1⅖ in the left front. There were no other significant findings in the limb on examination. There was considerable proliferative granulation tissue developing. Another ultrasound of both forelimbs showed tracts of infection extending to the surface of the superficial flexor tendons, but the tendons themselves remained unchanged.

On subsequent visits the swelling and odor in both limbs decreased. Topical debridement was performed twice alternating an antibiotic with steroid (Dermalone) and a collagen based ointment (Derma Gel) applications. The SAA had returned to 0.

Surgical debridement at a referral hospital was recommended nearly 60 days from injury due to significance of proliferative granulation tissue. While at the referral center another ultrasound was performed prior to surgery. The right front revealed a rupture of the paratenon with severe disruption of the superficial flexor tendon at the level of the wound. The deep digital flexor tendon showed mild fiber changes as well. The left front revealed a lesion in the superficial flexor tendon as well as a ruptured paratenon 10–30 cm distal to the accessory carpal bone. The abundant 14

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granulation tissue was debrided under standing sedation twice while at the hospital over 3 days.

Post surgically, Acell-UBM—an extracellular matrix scaffold—was applied under sterile bandages. It is necessary to keep the scaffold saturated with saline-soaked gauze under the bandage with continued saline application via a Penrose drain. Within 4 days, the granulation tissue remained flat and uniform in both front legs. Two weeks from the start of the scaffold applications, the left front wound no longer required treatment topically and the right front wound had reduced by greater than 25%. One month postsurgical debridement the right front did not require further treatment topically (Figure 4).

Ultrasonography was performed 5 days from the last topical treatment of the right forelimb. Imaging revealed significant core and palmar border disruption of the superficial digital flexor tendons in both forelimbs. Due to the delicate nature of the newly healed skin and risk of infection, it was elected to delay intralesional injection of the tendons. One month later, another serial ultrasound was performed with both superficial flexor tendons appearing to have significant healing. Regenerative laser therapy was elected in place of injection using a Class 4 Epica unit.

Diagnostic Approach

Serial ultrasounds were vital in diagnosing, and following this case. (Figures 5A, B). It allowed monitoring of the subcutaneous swelling and evolution of the palmar metacarpal soft tissues developing involve-

FIGURE 5A. AND FIGURE 5B.

ment. The early swelling of the limbs were never a hindrance to diagnostic imaging as the edema acts as a “stand-off ” pad, creating well-defined images of the superficial structures. While the wounds are active, ultrasound of the tissues from the medial and lateral aspects of the limb allow a way to monitor structural involvement without having the transducer near the wounds.

Thermography also aided in identification of the scope of the areas involved. The constriction creates such damage to the vasculature that the areas likely to necrose appear black from complete lack of blood flow and therefore results in a decrease in temperature reading (Figure 6). A “bowed” tendon, in the generic sense, would appear white hot throughout the structure.

Conclusions/Management

These severe constriction injuries and the resulting necrosis require intense monitoring and treatment from incidence to resolution. Early identification and treatment are paramount. Initially, strict stall rest is implemented with acute cold therapy, whether it is chosen to be performed at home or referred to a facility with a cold spa. It is recommended to have cold therapy 2–3 times per day while the skin is intact. As stated previously, the signs will vary in timing and severity and directly depend on the amount of circulatory compromise. Therefore, owner preparation for the progression of lesions should be handled directly along with realistic discussions of prognosis and duration of treatment.

The progression of swelling, hair loss, serous

FIGURE 6.

weeping and then tissue sloughing has been consistent in cases. Therefore, once the tissue sloughs and becomes wounds, topical care can begin. Infection is often unavoidable once necrosis begins, becoming a management-and-monitoring situation. Multiple ModernEquineVet.com | Issue 2/2019

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TECHNICIAN UPDATE

Teaching Points Although we don't see many compression injuries, this case epitomizes the intensity of veterinary therapy needed in serious cases.

Even though this case was in run-downs, these injuries have been known to occur in boots and polos as well.

Working closely with owners and caregivers, we can educate and prevent injuries related to circulatory compromise from constriction of the limb.

CBC/chemistry panels are performed to evaluate how the patient is handling antibiotic therapy in addition to serial SAA tests to follow the level of infection. Topical treatment differs initially as you are dealing with active necrosis. Once the necrotic tissue sloughs, wound management is begun. In this case, an exuberance of proliferative granulation tissue had to be treated alternating with Dermalone every third day to shrink the tissues, plus Dermagel—a collagen based product—on the other days. The use of topical steroids too frequently can stagnate healing.

A Class 4 laser was used early on for wound management and later for its regenerative capabilities. Each was a series of 10 treatments and was only separated due to the lack of access to the area under the bandages during the use of the Acell-UBM. In between the uses of the laser, a scaffold sheet of AcellUBM—an extracellular matrix scaffold—was applied a total of 8 times. The use of these sheets is twofold— to heal the wound, as well as the underlying tendon tissue. The first several applications are left on for 2-day intervals and then—as the wounds were improving—the Acell and bandage were left in place for 3–4 days. A Penrose drain was placed between the bandage and gauze as a conduit to infuse 0.9% saline over the matrix, which is necessary to prevent the scaffold from drying out and becoming inactive. The scaffold’s inherent antimicrobial ability allows you to use the product even if infection is present.

Complication by infection is almost always an inevitability and can be a catastrophe. Necrosis of the tissue in the areas affected is unavoidable, and is caused by severe circulatory compromise. Erosion into the superficial flexor tendon can, in some cases 16

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be avoided but the proximity of infection to these tissues is why constant serial ultrasounds are necessary.

Changes can appear quickly. Lameness and sensitivity are early indicators of an evolving issue.

Prognosis is case dependent. This patient is returning to training to continue to be a racehorse It is wholly dependent on the level of structural involvement and healing post infection. He will continue to have serial ultrasound exams of both forelimbs’ palmar metacarpal soft tissues as he progresses through his training. The scar tissue has continued to remodel. However it is unlikely he will ever have a normal appearance to either forelimb.

Intense therapy and monitoring can increase the chances of a successful outcome. These cases are rare—seemingly isolated to horses running long distance in either bandages or boots. In 13 years, I have seen 4 cases. Unfortunately, one was fatal, after the superficial digital flexor tendon suffered a partial rupture injury in one forelimb during the race. The infection, even with aggressive therapy, eroded into the injured tissues and it became apparent that support of the limb was too compromised.

Still another case had been evaluated and given a very poor prognosis by other veterinarians who examined him. In that case, the owner—who rode him in his race—was determined to save him. He ran a 3-mile race in boots on both forelimbs. This horse had a unilateral injury that had already sloughed, but remained somewhat necrotic in nature and the superficial flexor tendon was fully exposed and frayed with some “strands” freely moving within the wound.

Seventeen applications of extracellular matrix scaffold later, the skin had closed and ultrasounds showed an intact—although biloded—superficial digital flexor tendon. He was foxhunted for several years before retirement where he still lives to this day. The final horse incurred his injuries wearing boots in a 3-mile race over fences. Bilateral injuries were treated and he returned to racing and foxhunting.

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Acknowledgements

Dr. Cooper Williams VMD, DACVSMR Dr. Magda Stewart DVM Nor Mar Farm LLC

About the author

Born into the horse world as the daughter of a barn manager and a blacksmith, Jessica has enjoyed 15 years of working with Cooper Williams VMD, DACVSMR, in his sports medicine practice, Equine Sports Medicine of Maryland.

AAEV T M E M b E r s h i p Membership in the AAEVT is open to all veterinary technicians, assistants, support staff and those employed in the veterinary health care industry worldwide. Student membership is open to those currently enrolled in an AVMA/CVMA accredited veterinary technology program.

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AAEVT Objectives • • • •

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• 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.

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