the modern equine vet july 2015

Vol 5 Issue 7 2015www.modernequinevet.comEquine Vet

The Modern

Injecting the navicular bursaUltrasonography & palpation for colic

MysteryWound

2 Issue 7/2015 | ModernEquineVet.com

Table of ConTenTs

OrThOpedIcsIs there a better way to inject the navicular bursa? ....................................................4

GasTrOInTerOlOGyUltrasonography and palpation for colic .........................................................................6

nUTrITIOnBioactive proteins and their role in health ..................................................................14InfecTIOUs dIseases eIV increases in older horses .............................................................................................16

newshappy anniversary, ruffian .........................................................8pony up an immune response ....................................................9 reduced oxytocin and retained fetal membrane ........10diffusion of mepivicaine from tendon sheaths ............15

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Big thoroughbred with big infection

cOVer sTOry: 12

Cover: courtesy of New Bolton Equine Hospital

SaleS: robin Geller • [email protected]

editor: Marie rosenthal • [email protected]

art director: Jennifer Barlow • [email protected]

contributing writerS: paul Basillo • Kathleen Ogle louisa shepard • carrie hammer dVM, phd

coPY editor: patty wall

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Equine VetThe Modern

advertiSerSMercK animal health ................................................ 3luitpold animal health ............................................. 7

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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.

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 post-treatment. 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.

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 estrus during the transition period. Estrus will be suppressed in mares exhibiting prolonged behavioral estrus either early or late during the transition period. Again, the posttreatment response depends on the level of ovarian activity. The mares with greater ovarian activity initiate regular cycles and conceive sooner than the inactive mares. Regu-Mate® (altrenogest) Solution 0.22% may be administered early in the transition period to suppress estrus in mares with inactive ovaries to aid in the management of these mares or to mares 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. Women who are or suspect they are pregnant. 2. Anyone with thrombophlebitis or thromboembolic disorders or with a history of these events. 3. Anyone with cerebral-vascular or coronary artery disease. 4. Women with known or suspected carcinoma of the breast. 5. People with known or suspected estrogen-dependent neoplasia. 6. Women with undiagnosed vaginal bleeding. 7. People with benign or malignant tumors which developed during the use of oral

contraceptives or other estrogen-containing products. 8. 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.

* 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

DOSAGE CHART:

Approximate Weight Dose in Pounds in mL 770 7 880 8 990 9 1100 10 1210 11 1320 12

orThopedIC

Is there a better way to inject

navicular burSa?

ModernEquineVet.com | Issue 7/2015 5

B y M a r i e r o s e n t h a l , M s

Some clinicians worry about hitting the deep digital flexor tendon and possible cumulative damage.

Although injection of the na-vicular bursa often is performed from the palmar aspect of the limb, a better option might be approaching from the lateral aspect so that one can avoid penetrating the deep digi-tal flexor tendon (DDFT), according to a recent study.

“Some clinicians are concerned regarding DDFT puncture and worry about possible cumulative damage,” explained Alexander daniel, bVetMed, MS, DAcVS, an equine surgeon at reid and Associates Equine clinic in Loxa-hatchee, Fla. “The only way to avoid this is to approach the bursa from the lateral aspect.”

Injection from the palmer as-pect penetrates the DDFT, requires the limb to remain flexed during

the injection and does not often result in the retrieval of enough

synovial fluid for testing if infection is suspected, the

researchers said. They wanted to find a

better technique for the radiographic guided in-jection of the navicular bursa that could avoid

these issues. In a prospective clinical and ca-

daver study, Dr. Daniel and his col-leagues evaluated a lateral injection technique.

“our main goal was to ensure that the DDFT would not be punc-tured since this tendon is always punctured using the traditional pal-mar approach. We also wanted to see what structures might be punc-tured from the lateral approach. We did this by comparing radiographs and MrI with the needle in place to allow us to correlate what we do in a clinical setting [inject under ra-diographic guidance] with MrI,” he said. (only the cadaver limbs were examined using MrI.)

The researchers placed 40 cadaver equine limbs in a stand to stimulate weight bearing and then injected them using a lateral injection tech-nique. They also laterally injected 31 living horses that presented with palmer foot pain.

The researchers were successful in injecting all 71 limbs. They found that the relative risk of punctur-ing the distal interphalangeal (DIp) joint was 19 times higher (95% cI 1.3–285.4, p<0.001) when the distal interphalangeal (DIp) joint was dis-tended than in a more normal posi-tion. The relative risk of puncturing the DFTS was 2.7 times higher (95% cI 1.0–7.2, p=0.06) when the DFTS was distended than in normal limbs. They were able to aspirate synovial fluid from the navicular bursa in 47% of clinical cases. Three of those

appeared to be septic.“There are typically two situa-

tions we need to place a needle into the navicular bursa, either we are concerned regarding a septic process and need to sample the bursal fluid or we need to administer a therapeu-tic to treat a lameness issue,”he said.

“We found that the position of the needle helps us obtain fluid more consistently from the lateral ap-proach than the palmar approach. This is crucial as part of the decision process, especially if surgery might be involved, e.g. due to infection. If we are using a therapeutic such as IrAp [Interleukin-1 receptor Antagonist protein], there are some horses that need a series of injections and the lateral approach allows us to do this without placing a needle through the tendon on multiple occasions.”

The researchers wrote that even though there was no clear evidence to show that penetrating the DDFT joint repeatedly causes harm, they felt that the lateral approach, which avoids this, was a better option be-cause it does not affect any tendon, ligamentous or cartilage.

There is a risk of synovial penetra-tion which could spread organisms if there is a deep digital flexor sheath or DIp joint infection, so synovial fluid should be analyzed first to avoid in-fecting the bursa, he added. MeV

Daniel AJ, Goodrich LR, Barrett MF, et al. An optimized injection technique for the navicular bursa that avoids the deep digital flexor tendon. Equine Vet J. 2014 Dec 23. doi: 10.1111/evj.12402. [Epub ahead of print]. http://onlinelibrary.wiley.com/doi/10.1111/evj.12402/abstract;jsessionid=37e641457FF2F5278c1a2a95d273858e.f03t03

For more information:

Is there a better way to inject

navicular burSa?

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In the examination of a horse with abdominal pain related to colic, the combined overall pic-ture provided by transabdominal ultrasonography and palpation per rectum (ppr) is greater than the sum of its parts.

“If we combine these findings, we are able to gain much more infor-mation about the ‘black box’ inside our patient than we would be able

to from either one alone,” explained tracy norman, DVM, DAcVIM, associate veterinarian at the blue ridge Veterinary clinic in Virginia.

limitations

While both modalities are im-portant for the overall picture, there are limitations to each. rec-tal examination may not be pos-sible in certain patients due to

age, infirmity, or size. In a very large horse, palpation past the pel-vic rim may be challenging. The space eaten up by gas distention and pregnancy may also get in the way of worthwhile findings. Even in ideal conditions, palpation via rectum is only useful to ascer-taining the situation in the caudal third of the abdomen.

For ultrasonography, gas dis-

Ultrasonography and palpation:

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PerFect togethertention can be a limitation as well. “If a horse has a gas-filled colon pressed up against the body wall, the only thing we’re going to see is the gas-filled colon,” Dr. Norman explained here at the 60th Annual AAEp convention. patient charac-teristics, such as thick skin, coarse hair, dirt in the haircoat, and excess adipose tissue can also hamper ul-trasonographic examination.

The other limitation is environ-mental. While some clinicians have the benefit of working in a climate-controlled hospital environment, the vagaries of weather can hamper examinations in the field.

When a cold horse vasocon-stricts, the sound waves are going to have a much more difficult time penetrating to the area of interest. A blanket can be used to warm bodies in colder temperatures, but

most horses with painful abdo-mens will have spent most of the day wallowing in cold mud.

Time is money recent studies have investigated

the utility of brief, limited, targeted ultrasonographic exams, and Dr. Normal reported the news is prom-ising. “With a little training and practice, most of us can become pretty good at performing quick examinations to identify important information without a prohibitive-ly expensive bill for the client.”

The Fast Localized Abdominal Sonography (FLASH) exam is the most common of these limited ex-aminations. It uses 7 discrete win-dows on either side of the horse’s abdomen and cranioventral tho-rax to obtain specific information about the horse, such as:

tools of the trade“Palpation per rectum does not take much in the way

of equipment,” Dr. Norman said. “You’re going to need a lot of lube, and you’ll probably want a rectal sleeve of some type. Proper restraint is important for the patient’s safety and for ours. I’m not a tall person, so my footstool is standard equipment.”

For diagnostic ultrasonography, it is easy to understand why it was initially dismissed as a useful diagnostic modality for acute abdomen. The machines were large, they were very expensive, and the images were difficult to interpret. Often, referral services were the only places that could afford the type of probes that had a frequency low enough to meaningfully penetrate in the horse’s abdomen.

“However, technology is certainly coming along at a wonderful pace,” she explained. “There are commercial handheld units that are about the size of an iPod. Resolutions have improved, and the prices have come down. Units with battery packs are also available, which allows us to operate in areas where we don’t have a hard power source.”


GasTroenTeroloGy

• Is bowel present in the nephrosplenic space?

• How much peritoneal fluid is present, and what does it look like?

• Is there small intestine visible, and what does it look like?

• Is the diaphragm intact?• Is the stomach distended?With those questions in mind,

the clinician can place the ultra-sound probe in the corresponding areas, collect the pertinent infor-mation, and move on.

“Even a relatively inexperienced sonographer can finish that exam in about 10 minutes,” Dr. Norman said. “We have to stick around to see what the horse is going to look like after the xylazine wears off, so you might as well scan the horse while you’re waiting.”

large colon and cecumcommon things happen com-

monly, and so the large colon and the cecum are often the focus when eval-uating horses with abdominal pain.

“These sites are often impli-cated in patients with abdominal pain because they can do a lot of things,” Dr. Norman said. “They can get stopped up, they can spasm, they can wander around to aberrant places, they can twist and telescope into themselves, and they can get infected.”

ppr is an important part of the evaluation for impaction colic in-

volving the pelvic flexure and the cecum. Ultrasonography tends to be less revelatory in cases where the impaction has not been in place long enough for vascular compromise of the colon. It can be difficult to look at a normal colon and be able to tell where the colon wall ends and the intestinal contents begin.

For large colon displacement, the two modalities can work in concert. “on rectal examination in a horse with left displacement, we can feel the left colon cours-ing up through the nephrosplenic space,” Dr. Normal explained. “It’s difficult to say whether the colon is just ‘up there’ or if it’s entrapped in the space between the spleen and the kidney. on ultrasound, we get a better picture of this.”

In these cases, the classical im-age involves the spleen. Deep and

dorsal to the spleen, a large loop of gas-filled bowel can be visualized. The image of the kidney is ob-scured by the gas. In contrast, it is possible for the colon to be on top of the spleen, but not entrapped in the nephrosplenic ligament.

In a patient with large colon displacement on the right, ultra-sonography can be helpful as well. on rectal palpation, a taut band can be felt coursing horizontally across the abdomen where it does not belong. If the bowel is empty, this finding may be missed.

“If the bowel is full, it may be up where we can detect it,” Dr. Nor-man said. “If it is sunk down to the bottom of the abdomen, we may miss that on palpation. Finding edema of the large colon is highly suggestive of vascular compromise. you do not want to stick your arm into a horse with a large colon vol-vulus and restricted blood flow. Those horses get taken straight to surgery, because time is trauma.”

palpation of the horse’s rectum will generally yield results from the caudal third of the abdomen. Trans-cutaneous ultrasonography of the abdomen is useful for visualizing the outer third or sometimes half of the abdomen, including some solid organs. If the information from both of these modalities is combined, cli-nicians are afforded a much more complete picture than either one by itself. MeV

The large colon and the cecum are often the

focus when evaluating horses

with abdominal pain.

elMont, nY – Cornell Ruffian Equine Specialists celebrated their first anniversary on June 25 with an event held at the practice, located right across the street from Belmont Park. Guests included Long Island-area owners, trainers, veterinarians, and other horse lovers.

dean Michael Kotlikoff announced that the client entrance at Ruffian would be named the Dan and Jane Burke Foyer, in recognition of the couple’s support of the equine program. It’s a longstanding relationship that began when Dan Burke brought his first horse to Cornell in the early 1950s.

Ruffian opened on May 7, 2014 with dr. nixon, and drs. lisa Fortier and norm ducharme as the original medical team. The practice focuses on equine athletes, from Thoroughbred and Standardbred racehorses to sport horses that compete in dressage and jumping. Primary care veterinarians refer their patients

for advanced diagnostic and medical care. Ruffian initially offered leading-edge orthopedic, respiratory, imaging and regenerative medicine services. dr. Kyla ortved and dr. Samuel hurcombe joined Ruffian in August, adding general surgery and emergency and critical care to the list.

In their first year, Ruffian specialists and staff served about 1,000 horses, performing hundreds of procedures including bone scans, respiratory surgeries and fracture repair.

The sophisticated imaging services at Ruffian expanded in June to include standing magnetic resonance imaging (MRI). Looking ahead, Dr. Nixon said the facility was planning to obtain a robotic CT scanner that can produce images of a horse’s entire body and an aquatread rehabilitation system for rehabilitation. MeV

happy anniversary, ruffian


news noTes

The immune system of the Shetland pony can re-spond to midge bites in a way that prevents—rather than triggers—allergic reactions, researchers said.

“To our knowledge, this is the very first study of a natural allergic disease in which we can show that immune responses to allergens can take two direc-tions, either leading to allergy or to tolerance,” said dr. dietmar Zaiss, of the University of Edinburgh’s School of biological Sciences, who led the study.

It was previously thought that ponies that do not suffer an al-lergic reaction to bites do so be-cause their immune system does not recognize allergens carried by the insects, and as a result do not respond. However, the Scottish researchers showed that all horses respond, and that their immune system can act in two different ways in response to the irritants in midge bites.

one of these responses produc-es allergy symptoms, such as itch-ing and inflammation, while the other prevents an allergic reaction, researchers said. The team found that after being exposed to midges, the equine immune system releases various cytokines that affect the behavior of other cells. ponies that react to midge bites release cytokines—interleukin 4 (IL-4)—that trigger allergy symptoms. In ponies not sen-sitive to bites, another cytokine—interferon-gamma (INF-g)—is released, which blocks different immune cells that would otherwise trigger allergic reactions.

Allergies are caused by a complex interaction be-tween genetic and environmental factors. researchers said the reason why some individuals develop sensi-tivities to certain substances, while others do not, is not fully understood. It is unclear what causes the im-mune system to activate a protective response over an allergic one, the team said.

Shetland ponies’ immune response to insect bites is helping scientists understand how people could be prevented from developing allergies. The ponies’ im-mune response to midge bites is similar to what hap-

pens in people with allergies. Understanding what triggers allergic reactions could help researchers come up with ways to stop people developing sensitivities.

“We believe this finding could have direct practi-cal implications, for example, by helping immune re-sponses to choose the right direction in individuals who we would like to protect from developing occu-pation-associated allergies,” Dr. Zaiss said.

The study, published in the journal PLOS One, was funded by the Dutch Foundation for Technical Sci-ences (STW) and was carried out in collaboration with researchers in the Netherlands. MeV


CMeulenbroeks C, van der Lugt JJ, van der Meide NMA, et al. Allergen-specific cytokine polarization protectsshetland ponies against Culicoides obsoletus-induced insect bite hypersensitivity. PLOS ONE, 2015;10:e0122090 DOI: 10.1371/journal.pone.0122090http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122090

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Pony up an immune response or not

“To our knowledge, this is the very first study of a natural allergic disease in which we can show that immune responses to allergens can take two directions, either leading to allergy or to tolerance.”

Dr. Dietmar Zaiss, University of Edinburgh’s School of Biological Sciences,

TherIoGenoloGy

reduced oxytocin expression in the uterus may be a contributing factor to the high incidence of sec-ondary uterine atony and retained fetal membrane in heavy draught mares. This may be related to increas-ing age, according to polish researchers

researchers from the University of Warmia and Mazury, in olsztyn, poland, investigated the expres-sion of oxytocin receptors in heavy draught mares af-fected by retained fetal membranes. The researchers thought that one reason for the high incidence (50%) of retained fetal membranes in heavy draught mares may be a difference in the expression of uterine oxyc-tocin receptors.

The researchers obtained placental biopsies from eight mares, four of which had passed fetal membranes normally within three hours of parturition (control mares) and four that retained fetal membranes due to secondary atony of the uterus. The mares with secondary atony of the uterus and retained fetal membranes were signifi-cantly older than control mares (average age in each group was 13 and 5 years respectively).

c hemi lumines cent western blotting was used to estimate the amount of oxytocin receptors in pla-cental tissues (endometri-um and allantochorion). In placental tissue from mares with retained fetal membranes, oxytocin expression was found to be 50 times less intense than in the placental tissue from control mares. Immunocytochemistry was used to deter-mine the location of oxytocin receptors in the placental tissue. In cases of retained fetal membranes, the staining for oxytocin recep-tor expression was hardly visible. In control cases the staining was more intense, defin-ing the locations where receptors were ex-pressed. Expression of oxytocin receptors was particularly evident in the region where

the endometrium and allantochorion meet. As oxytocin expression is thought to be similar

in both the endometrium and myometrium around the time of parturition, the researchers suggest that oxytocin expression in the myometrium may also be reduced, contributing to secondary uterine atony observed in cases of retained fetal membranes. It was postulated that age-related changes to receptor num-bers and binding affinity may be related to this reduc-tion by as yet undetermined mechanisms. MeV

reduced oxytocin expression with retained fetal membranes


Rapacs-Leonard A., Ras A, Catka J, et al. Expression of oxytocin receptors is greatly reduced in the placenta of heavy mares with retained fetal membranes due to secondary uterine atony. Equine Vet J. 27 APR 2015 (Epub ahead of print) DOI: 10.1111/evj.12426. http://onlinelibrary.wiley.com/doi/10.1111/evj.12426/full

when membranes were retained, oxytocin expression was 50 times lower.

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RESULTS IN JUST 14 DAYS


woUnd Care

Although Tractor was not meant for the racetrack—second-to-last in his best race—he was clearly born to fly over open hills and jumps and was runner-up in the

2015 pennsylvania Most-Wanted Thoroughbred competition at the World Horse Expo in Harrisburg.

Sponsored by the retired race-horse project, only four horses are

chosen out of dozens of entries, based in part on a persuasive essay.

but Tractor almost didn’t com-pete. Not long after Monica Fiss started training Tractor, a swol-

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Medical Mystery: big thoroughbred

with big infection


len spot appeared under his belly. It didn’t seem to bother him, but it did her. An experienced horse-woman, she had never seen any-thing like it.

“you could push your finger in it, and it was like pushing into a sandbag. The impression would stay,” said Fiss, who owns and op-erates a training, lesson and board-ing barn, Windswept Stables, in Aberdeen, Md.

The local veterinarian pre-scribed a topical medicine, and said to keep an eye on it. one day, Ms. Fiss saw a little scab. “It

came off, and this really gross liq-uid came out, like a quart of it,” she said. “The smell was horren-dous. It was mostly yellowy, white, cloudy pus. The poor guy.”

The vet prescribed antibiotics, and a regimen of flushing with an antiseptic and salt water. but the ab-scess “wasn’t going away,” she said.

So off they went to Manor Equine Hospital for an ultrasound, which showed a large abscess in the abdomen. “It was surgery, or death,” Fiss said.

She brought him to New bolton center in Kenneth Square, pa. Through a more advanced ul-trasonography technique, eric J. Parente, Ab, DVM, professor of

surgery, discovered that the abscess was actually in the abdominal wall. The sack was enormous: 10 inches long and two inches wide.

“We defined the margins, and it was too big to open the whole thing up, because of the risk of body wall herniation,” Dr. parente said. “It was too big to take the whole thing out, too, because there wasn’t enough margin to put it back together.”

The goal was twofold: to try to find out what caused the abscess, and to effectively drain it, Dr. par-ente said. With ultrasound guid-ance, he inserted laparoscopic can-

nulas into the abscess sac through two small incisions, and flushed it out. He then inserted a special drain to administer a high concen-tration of local antibiotics over the next week. Tractor was put on sys-temic antibiotics as well.

once home, Ms. Fiss continued the care, administering a strong antibiotic three times a day for two weeks, as well as cleaning the wound site. Tractor was in quaran-tine because of the drug’s hazard to humans. Fiss wore safety goggles and gloves and a medical gown.

She started riding him again about three months later, starting slow with walk-trot, then bring-ing up to a canter, jumping, and

going cross country. “Then, one day, I looked down,

and the abscess was back,” she said. “It was leaking. I called Dr. parente in tears. I thought we were going to have to put him down.”

“I get a little emotional with this horse,” she continued. “I thought he was a goner. It was so sad for me.”

but Dr. parente told her to not give up. “I think what happened is that the infection hadn’t been

completely resolved, so we put Tractor back on antibiotics,” he said, which resolved the infection.

Although Dr. parente solved the problem, he did not pinpoint the cause. “It is very unusual to have an abscess without a reason, puncture, or previous surgery,” Dr. parente said. “There has to be some physiological reason. you have to presume there was a wound there at some point.”

Ms. Fiss said neither she nor the breeder noted any wound. So for now, it remains a mystery. MeV

since the wound was too large to open because of the risk of body wall herniation, the goal was to find out what caused the abscess and to effectively drain it.

tracktor competing after treatment. Photo courtesy of New Bolton Center.

Optimal horse health and well-being are the goals of every veterinarian and owner whether the horse is a high performance athlete or a beloved companion. providing good nutrition is the foundation for achieving this goal; however, there are times that supplements or other treatment options are needed to balance what the horse requires. Making decisions on which supple-ment or treatment to recommend can be daunting for even the most knowledge-able owners, as there are hundreds of oral supplements on the market adver-tised to sup-port a variety of conditions.

your advice is very important.one new supplement released

last year is marketed as an orally dosed serum protein product. Al-though administering oral serum to neonatal foals with failure of passive transfer or with the use of injected autologous conditioned serum (AcS or IrAp) may be familiar, the thought of orally dosing serum pro-teins to horses may seem foreign.

Traditionally, feeding of protein is talked about from a nutrition sense; i.e. the proteins incorporated in grasses and grains are ingested by

the horse and broken down into

amino acids in the stomach and small intestine. These amino acids are then absorbed and re-assembled back into proteins that the body uses for various needs. However, in recent years, science has shown that after ingestion, some proteins can act within the body in ways that are different from the traditional nutrition pathway. These proteins have been named bioactive proteins and are defined differently among various scientific disciplines. Ani-mal nutritionists define bioactive proteins as proteins that, when ad-ministered to the animal, improve animal performance and well-be-ing beyond what can be explained solely by the understanding of basic nutrient digestion and absorption.

For animals, the main sources of bioactive proteins are products purified from dried serum or milk. Milk-based oral products for horses have been commercially available for approximately 10 years, while the first serum-based oral product was introduced in 2014. Although relatively new to the horse indus-try, the beneficial effects of serum-based bioactive proteins are well documented in humans and food animals and products have been

available for over 30 years.Serum is the fluid portion of blood remaining after

the blood cells clot

bioactive ProteinSB y c a r r i e h a m m e r d V M , p h d

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and their role in horse health


Dr. Hammer is the director of the Equine Science program at North Dakota State University and also serves as the State Horse Extension Specialist.


and is rich in bioactive proteins, in-cluding immunoglobulins, transfer-rins, cytokines and growth factors. Immunoglobulins are antibodies produced by the immune system and are responsible for protecting the body from infectious agents and toxins. Immunoglobulins act through a variety of complex mech-anisms, ultimately rendering a dis-ease unable to function.

Transferrins are proteins that bind iron, an element necessary for the growth and development of many bacteria. Thus, transfer-rins create a low-iron environ-ment that affects bacterial sur-vival. Finally, there are numerous cytokines and growth factors present in serum, including inter-leukin-1, platelet-derived growth factor, transforming growth fac-tor and insulin-like growth fac-tor. cytokines and growth factors function in cell signaling, tissue growth and many various cellular activities.

one proposed mechanism-of-action of bioactive proteins is through modulation of the immune system, which is the body’s defense against disease-causing patho-gens—bacteria, viruses and toxins. bioactive proteins reduce the ability of pathogens to attach and repro-duce in the body, and also aid in tissue repair. These activities lead to beneficial support and maintenance of the immune system.

overall, the beneficial effects of bioactive proteins are more pro-nounced in higher stress situations, as these situations are known to in-

crease the release of inflammatory cells. Animals can experience high stress as a result of illness and dis-ease or other external factors, such as transportation, weaning and so-cial or environmental changes.

past research has shown that se-rum-based bioactive proteins help to manage symptoms and stress associated with illness. Increased survival and performance of pigs and calves suffering from respi-ratory and intestinal disease has been reported in numerous stud-ies. In humans with irritable bowl syndrome, serum-based bioactive proteins reduced the number of symptomatic days. Although there are data supporting the use of bio-active proteins in farm animals and humans, the data in horses are limited. A recently reported study by Dr. Josie Coverdale from Texas A&M University demonstrated improved stride length at the walk and trot in regularly exercised Quarter Horse geldings that were given serum-based bioactive pro-teins for 14 days. As the science in this area is strong in other species, one would expect to see additional equine studies published in the near future.

The value of bioactive proteins in supporting health and reducing the effects of disease are well docu-mented in animal agriculture and human research; however, the horse industry is only beginning to tap into these benefits. The future in this area is bright with the potential to set a new standard for horse health and performance. MeV

news noTes


diffusion of mepivacaine from tendon sheaths

Injecting the digital flexor tendon sheath with mepivacaine at the standard dose results in sufficient concentration for analgesia only in the digital flexor tendon sheath.

There was no clinically relevant diffusion to adjacent synovial structures, according to a study by researchers from Ghent University in Belgium.

The researchers wanted to evaluate the extent of diffusion of mepivacaine to adjacent synovial structures following intrasynovial injection into the digital flexor tendon sheath.

Eight horses with no clinical or radiographic orthopedic abnormalities were included in the study. Under general anaesthesia in lateral recumbency, each horse had synoviocentesis of the digital flexor tendon sheath performed on the uppermost forelimb and hindlimb. At the same time, venous blood samples were obtained.

A standard dose of mepivacaine (1 mL/50 kg) was injected into the same limbs from which synovial fluid had been sampled. Samples of synovial fluid were then aspirated from the treated tendon sheaths as well as the metacarpophalangeal/metarsophalangeal joint, proximal interphalangeal joint, distal interphalangeal joint and navicular bursa in the injected limbs and the contralateral metacarpophalangeal/metatarsophalangeal joint 15 minutes (forelimb) and 60 minutes (hindlimb) post-injection with blood samples at the same points. The protocol was repeated two weeks later except that the forelimb sites were sampled at 60 minutes and the hindlimb sites at 15 minutes.

All tendon sheath injections resulted in mepivacaine concentrations within synovial fluid well above those required for analgesia. Very low mepivacaine concentrations were found in all adjacent synovial structures sampled, and even the highest of these was well below a clinically relevant level. The concentrations in adjacent structures were all higher at 60 minutes post-injection than at 15 minutes, with the exception of the navicular bursa. There were no statistically significant differences between the concentrations in each adjacent synovial structure. Concentrations in blood were also below clinically significant concentrations at both time points.

A limitation to the study, the researchers said, was that it was performed in sound horses, so more studies are needed. MeV


Jordana M, Martens A, Duchateau L, Haspeslagh M, et al. Diffusion of mepivacaine to adjacent synovial structures after intrasynovial analgesia of the digital flexor tendon sheath. Equine Vet J. 2015 Mar 31. doi: 10.1111/evj.12447. [Epub ahead of print]

A surveillance program de-tected an increase in equine in-fluenza virus (EIV) among older horses and previously vaccinated horses compared with earlier sur-veillance data.

based on the study results, lead

investigator nicola Pusterla, DVM, phD, DAcVIM, of the Department of Medicine and Epidemiology, School of Veterinary Medicine at the University of california, Davis, said that in some instances equine influenza vaccine may have provid-

ed suboptimal protection to horses that received the vaccine.

Equine influenza virus is a prev-alent respiratory pathogen, and it is easily spread through fomites, droplets and aerosoles.

“What truly characterizes these pathogens is their short reproduc-tive cycle, hence they are highly contagious because they spread rapidly,” Dr. pusterla said. “De-pending on the susceptibility of the population, the morbidity can be as high as 90% while the mortality is fortunately relatively low.”

It has a high financial impact to the equine industry leading to the cancellation of shows and quaran-tine of horses to prevent transmis-sion and spread, he said.

For the surveillance study, which was funded by Merck Animal Health, Dr. pusterla and colleagues collected samples of nasal secretions from horses with acute fever (≥ 101.5⁰ F) and respiratory signs (leth-argy, nasal discharge, coughing)from 239 veterinary practices in 38 states from March 2010 to Novem-ber 2013. The samples were shipped overnight to a laboratory where they were processed using quantita-tive testing with polymerase chain reaction (qpcr). Investigators then

eIV increases in

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older horsesIn some instances equine influenza vaccine may have provided suboptimal protection to horses that received vaccination.


Pusterla N, Kass PH, Mapes S Voluntary surveillance program for equine influenza virus in the United States from 2010 to 2013. J Vet Intern Med. 2015 Jan;29(1):417-22. doi: 10.1111/jvim.12519. Epub 2015 Jan 14.

http://www.ncbi.nlm.nih.gov/pubmed/25586234


compared their results to those ob-tained from an earlier EIV surveil-lance study, conducted March 2008 to February 2010.

of the 2,605 horses enrolled in the study, 230 were found to be qpcr-positive for EIV. The infected horses ranged in age from 3 weeks to 24 years (median, 6 years). A questionnaire was used to collect data about each horse’s vaccination status including time of vaccination and type of vaccine used. The vac-cine brand and manufacturer were not included. of the 230 tested positive for EIV, 84 had been previ-ously vaccinated, 15 were unvacci-nated and the status was unknown in 131 horses.

“For those who have ever dealt with questionnaires, sometimes it’s difficult to gather appropriate infor-mation. When it came to vaccina-tion, unfortunately 50% to 60% of the questionnaires had ‘unknown’” Dr. pusterla said at the American Association of Equine practitioners annual meeting.

Still, the investigators found that the same percentage of horses were found qpcr-positive for EIV in both the control and previously vac-cinated horse groups.

of the horses known to receive a vaccination, 69 received a killed ad-juvanted EIV vaccine, 5 received a modified-live EIV vaccine, and for 10 horses, the type of vaccine was not listed, Dr. pusterla reported.

“If you look at vaccine type used, the horses were predominantly vac-

cinated with a killed adjuvanted vac-cine. There was no significant differ-ence in the use of the vaccine when we compared control versus EIV-positive horses,” Dr.pusterla said.

“The majority of the horses had been vaccinated recently, less than 6 months versus 6 to 12 months or over 12 months,” he added.

When the results of the two surveillance programs were com-pared, the investigators found that horses testing positive for EIV in 2010–2013 tended to be older—5 to 10 and 10 to 15 years of age—than the horses that tested positive in 2008–2010. In the earlier surveil-lance program, 2008-2010, 50% of the horses testing positive for EIV were younger than 5 years of age.

“When we looked at the two dif-ferent pairs, we found that in the

more contemporary set we are deal-ing with older and previously vacci-nated horses. It's also interesting to see that within these, we see horses that predominantly have been vac-cinated less than 6 months,” he said.

Sequence analysis of the select-ed strains revealed the EIV iso-lates were clade 1 sublineage. Dr. pusterla explained that clade 1 vi-ruses are present in North Amer-ica, Europe, South Africa, Japan and Australia. clade 2 viruses are seen primarily in Europe, china, as well as India.

However, Dr. pusterla said, it is only a matter of time before clade 2 is active in the United States.

Dr. pusterla also cited surveillance data from the office International des Epizooties, which has reported on outbreaks of clade 1 and clade 2 in previously vaccinated animals.

“This brings the point and the possibility with vaccine available in North America, that in some instances we are dealing with sub-optimal protection. So I urge the in-dustry to really consider including epidemiologically relevant strains when it comes to equine influenza,” Dr. pusterla said.

He recommended including a strain that is present and caus-ing clinical disease in previously vaccinated animals, a strain that causes moderate to severe clinical disease, and a strain that is geneti-cally and antigenically different from what is included in a killed adjuvanted vaccine. MeV

older horses equine influenza virus is a prevalent

respiratory pathogen, and it is easily spread

through fomites, droplets and

aerosoles.


reach your veterinarians wherever they are, whenever they want.

fOr adVerTIsInG raTes and InfOrMaTIOn, eMaIlrobin gellar

Equine VetThe Modern

the modern equine vet july 2015

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