TheModernEquineVetDec12

The Modern

Equine Vet www.modernequinevet.com

Immune link to chronic

laminitis

December 2012 | Vol 1 No 5

Floating cheek teeth Drug testing Can't put them out to pasture?

Technician Update Recipe for obesity

Table of Contents

Cover story

4 Biology behind laminitis Chronic disease may be linked to altered immune system Cover photo by Makarova Viktoria/shutterstock

Dentistry

Floating cheek teeth?.............................................................................. 6 Try a little tenderness

Housing

Can't put them out to pasture?............................................................ 8 Active stable a good compromise

Sports Medicine

Testing for methylprednisolone .................................................12

Remains in body longer than thought

Technician Update

Immune response critical for influenza vaccination............16

Feedbag

20 Recipe for a fat horse Infectious diseases

14 New piroplasmosis treatment, test 15 New leaders for AAEP LEGAL DISCLAIMER: The content in this digital issue is for general informational purposes only.

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

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December 2012 | ModernEquineVet.com

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laminitis Biology behind

Chronic laminitis may be linked to altered immune system regulation

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December 2012 | ModernEquineVet.com

laminitis

Shutterstock/anakondasp

Photo courtesy of Samantha M. Steelman

linked to inflammatory proteins that regulate the immune system throughout the body, particularly in the gastrointestinal (GI) tract, according to a recent study that appeared in the journal BMC Veterinary Research, which is an open access journal at BioMed Central.

“Our results suggest that a number of proteins involved in immune regulation are expressed differentially in horses with chronic equine laminitis. In particular, the anti-inflammatory protein APOA-IV was elevated approximately twofold in foundered horses,” the researchers wrote in the article.

The researchers found that in horses with chronic laminitis, there is an increase in apolipoprotein A-IV (APOA-IV). This suggests that the condition is linked to a more general inflammatory state, especially of the GI tract, they said. This is the first study to describe changes in plasma proteins among horses with chronic laminitis, according to Samantha M. Steelman, PhD, MS, postdoctoral research associate, Texas A&M University, College of Veterinary Medicine.

Although no one knows the exact cause of chronic laminitis, it can be associated with insulin resistance and obesity, and can be preceded by colic, diarrhea and other diseases. Laminitis is prevalent among horses allowed to eat lots of lush, fresh grass especially after being kept indoors for the winter, according to the researchers. Inflammation can lead to irreversible rotation of the foot bones inside the hoof, and in 75% of cases, the inflammation becomes chronic founder, leaving the horse permanently lame.

Steelman and Bhanu Chowdhary, PhD, MVSc, BVSc&AH, professor and associate dean for research and graduate studies, at Texas A&M, found that the blood levels of 16 proteins were different in horses depending on whether or not they had chronic laminitis.

Apart from the laminitis, all the horses were in good health. Eleven of the proteins found, such as coagulation factor X, are released in response to wounding, coagulation and inflammation. The remaining proteins include fetuin A and B, which are involved in the acute immune response, immunoglobin, an indicator of increased antibody levels, and most importantly APOA-IV. “APOA-IV is produced by the small intestine. One of its functions is to tell the animal when it is full. It also has anti-oxidant and anti-inflammatory properties, which might explain the raised levels of APOA-IV,” Steelman said.

Photo courtesy of Samantha M. Steelman

Chronic laminar inflammation appears to be

Image of the master DIGE gel stained with deep purple showing equine plasma depleted of albumin and IgG.

Horses with chronic laminitis experienced alterations in the plasma proteome that reflect inflammatory changes that appeared throughout the body, not just the foot. Specifically, the increased complement proteins and acute phase reactants appear to cause a chronic activation of the immune system.

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For more information: Steelman SM, Chowdhary BP. Plasma proteomics shows an elevation of the anti-inflammatory protein APOA-IV in chronic equine laminitis.

BMC Veterinary Research 2012,8:179 doi:10.1186/1746-6148-8-179 http://www.biomedcentral.com/1746-6148/8/179/abstract ModernEquineVet.com | December 2012

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dentistry

Floating cheek teeth?

Try a little tenderness Less aggression best when floating cheek teeth B

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Don’t be over aggressive

when floating cheek teeth, cautioned Rachel Marshall, BVM&S, MRCVS, of the Royal School of Veterinary Studies and Roslin Institute at the University of Edinburgh in Scotland.

Cheek teeth overgrowths need to be floated because they can cause soft tissue lacerations and interfere with normal bitting and mastication, she explained. “However

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when treating, it is important to understand that the layer of secondary dentine protecting the pulp of the tooth can be very thin and so therapeutic reductions must take place over several occasions to minimize the risk of pulpar exposure.”

Marshall and her colleagues studied the cheek teeth of 15 horses to obtain a value for the thickness of secondary dentine (protective layer covering the pulp of the tooth) in

Above picture courtesy of Professor P. M. Dixon, The University of Edinburgh.

The above overgrown teeth are likely causing problems with mastication and soft tissue trauma.

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overgrown cheek teeth compared with normal teeth. They found that the secondary dentine layer in some overgrown cheek teeth could be very thin. The results were published recently in The Veterinary Journal.

“Overgrown teeth occur when the occlusal contact with the opposing tooth is reduced,” she said.

“This can occur for many reasons including a lost tooth, a tooth with

Above picture courtesy of Professor P. M. Dixon, The University of Edinburgh.

The overgrowth seen in this picture was causing soft tissue trauma to the area directly above behind the last molar.

sition, apical infection can then lead to dental sinusitis or the formation of an abscess in facial bones. Pulp exposure is also believed to be considerably painful,” she said.

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Shutterstock/Studio 37

weak or thin enamel, a displaced or fractured tooth or due to diastemata.”

Secondary dentine might be thinner because the horse's ability to provide the constant occlusal pressure from opposing teeth needed to lay down a normal thickness of secondary dentine might be missing from opposing teeth. Therefore, there will be less secondary dentine, she explained.

The study showed that it is better to float teeth in stages, rather than fully reduce the overgrowth in one treatment to avoid exposing the pulp beyond the secondary dentine. This study showed the secondary dentine thickness can be less than 2 mm thick.

“Reducing in stages, i.e., 2-3 mm every 3 months allows time for further dentine to be laid down over the pulp and the process of floating itself may actually stimulate further production of dentine, helping to rebuild what was ground down in the first one making the second floating safe. If there was no stimulation to produce more than we would grind straight into pulp the second time,” she told The Modern Equine Vet. Failure to reduce the cheek teeth in stages could lead to infection and pain for the horse, she added. Nobody likes a toothache!

Oral bacteria can infect exposed pulp. There is a risk that this may spread and cause apical infection of the tooth, which can ultimately kill the tooth.

“Depending on the tooth po-

For more information: Marshall R, Shaw DJ, Dixon PM. A study of sub-occlusal secondary dentine thickness in overgrown equine cheek teeth. Vet J. 2012 Jul;193(1):53-7. http://www.ncbi.nlm.nih.gov/pubmed/22112631 ModernEquineVet.com | December 2012

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housing

Can't put them

out to pasture?

Active stables are a good compromise between horses' and people's needs B y

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Active stables might be more beneficial and en-

Photos courtesy of Gundula Hoffmannn

courage positive behavior among horses rather than housing them in individual stalls, because individual stalls do not meet their need for social interaction and activity, according to a recent study of Icelandic horses.

The problem is particularly perplexing in countries like Iceland that have long, cold winters.

An active stable system is a type of group housing that allows horses to interact as a herd. All of the horses live together on a big paddock with shelter, feeding and resting areas, where they have to move from one area to another to perform certain functions, such as eating, rather than just standing in a stall in a barn.

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December 2012 | ModernEquineVet.com

ModernEquineVet.com | December 2012

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housing

An active stable system is a type of group housing that allows horses to interact as a herd, which is a normal lifestyle for equids. All of the horses are living together on a big paddock with shelter, feeding and resting areas, so that they must move from one area to another to perform certain functions, rather than just standing in a stall in a barn.

“This system should motivate the horses to be more active.

Therefore, the functional areas (feeding of roughage, feeding of concentrates, watering place, lying hall) are at different sides of the paddock,” explained Gundula Hoffmannn, DVM, of the department of engineering for livestock management, Leibniz Institute for Agricultural Engineering in Germany.

“The movement is important to prevent diseases of the locomotor system and respiratory tract,” she said.

There are some active stable housing in use in Germany, but this is the first one to be used in Iceland, where the study took place, explained Hoffmann. The aim of the study, which was published recently in the journal Animal, was to analyze the suitability of a group housing system under Icelandic conditions.

Eight Icelandic horses were observed in an active stable system, and their behavior and time budgeting were recorded. The effect of an automatic concentrate feeding station (CFS) on the horses’ behavior also was examined.

The researchers looked at the system in two periods. In the first period, the horses were fed concentrates manually, and in the second period, they were fed with a CFS. “The results showed a significant increase between the first and second trial periods in both the activity and the lying time of the horses with the use of the CFS,” she said.

“I undertook the study because I wanted to know the behavior of the horses in an active stable. In Germany, we already have many active stables but, in Iceland, this is the first one. We also wanted to see if this system would work during a strong winter,” she said.

They wanted to scientifically measure the activity of the horses, as well as the lying behavior (resting) of the horse.

“This kind of housing meets horses’ needs in terms of movement, rest, fresh air, social behavior and feed intake (feeding in little portions over the whole day),” she said.

They found: •E very horse could be feed individually with concentrates.

• The horses accepted the system, and • The horses showed good social behaviors.

In addition, there were positive effects on the horses' health and welfare, and the system makes less work for the barn manager because he or she isn't taking care of individual stalls, but the horses are always available to ride, ac-

cording to Hoffmann.

Hoffmann said that integrating any group of horses can take time, especially if they are not used to herd life, but most horses do adapt to this type of group housing.

“The integration of horses can take some time, like in every group. If a horse is not accustomed to group housing or has a very low rank index, it could have problems. But after some time, it is normally integrated to the group,” she said.

Although the horses may have been a little less aggressive in an active stable situation, Hoffmann said that most aggression really depends on the horse's life experiences, as well as its acceptance in the ranking social hierarchy. Having said that, she does think “the number of behavioral disorders will be lower in this type of housing.”

Hoffmann said she sees a time when all horse housing is developed like this. “I think that this is a good compromise between horses’ and humans’ needs. The horses would prefer a pasture, I think. But most of the horse owners don’t want group housing. They are afraid of injuries, etc. In Germany, 90% of all horses are living in individual boxes. It is very important that they spend most of the day time on a pasture or paddock together with other horses.”

Active housing would be applicable to other regions and countries, but ultimately, the barn manager should determine the housing set up.

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For more information: Hoffmannn G, Bentke A, Rose-Meierhofer S, et al. Influence of an active stable system on the behavior and body condition of Icelandic horses. Animal. 2012 Oct;6(10):1684-93. doi: 10.1017/S1751731112000699. Epub 2012 Apr 3. http://www.ncbi.nlm.nih.gov/pubmed/22717220 For more information about the active stables: http://www.aktivstall.de/ 10

December 2012 | ModernEquineVet.com

AAEVT Membership

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

AAEVT Membership • • • • • • • •

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

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

AAEVT Objectives • • • •

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

AAEVT Online Equine Certification Program

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

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

ModernEquineVet.com | October 2012 For more information visit www.aaevt.org

*American Association of Equine Veterinary Technicians and Assistants

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Methylprednisolone may be detected for longer periods B

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The United States Equestrian Federation (USEF) may change its screening method for therapeutic steroids based on a recent study that found that levels of a natural occurring steroid, hydrocortisone, decrease when horses are given a man-made steroid.

The study also found that levels of injected methylprednisolone stayed in the blood and urine longer than originally thought, which could affect USEF test results in performance horses.

In the study, researchers from The Ohio State University tested the pharmacokinetics of 100 mg and 200 mg methylprednisolone given as intra-articular injections in exercised horses. In addition, they looked at the relationship between methylprednisolone and naturally occurring hydrocortisone levels in five 3-year-old Thoroughbred mares to determine how long it takes to clear the drug from plasma and urine.

“We wanted to relook at the profiles in the blood and urine of this medication coming out of the 12

December 2012 | ModernEquineVet.com

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joint because it can drug test positive and may be affected by exercise in sport horses,” explained Alicia L. Bertone, DVM, PhD, DACVS, The Trueman Chair in Equine Medicine and Surgery at the department of clinical Sciences at The Ohio State University.

The five mares were conditioned for three weeks on a treadmill, then they received therapeutic doses of methylprednisolone in two joints in the hind limb. Plasma and urine samples were collected from each horse before the injections and at various times for eight weeks after receiving the injections.

The researchers chose methylprednisolone because intraarticular administration of this medication is a common method of reducing joint inflammation and pain in horses with lameness due to joint injury or disease, according to Bertone.

They found that the methylprednisolone could be found in the plasma and blood for longer than the two weeks currently allowed

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in the drug-testing guidelines. This means that a horse could test positive, even if the methylprednisolone was given 14 days before the event — and could be disqualified, unless the federation received a medications disclaimer form signed by the veterinarian that stated when the methylprednisolone was given, how much and why. It is important for the public to understand that the medical use of these steroids under a veterinarian's recommendation is acceptable, but a medications form needs to be on file prior to showing if under the guideline withdrawal time.

Bertone said that the group’s results were likely different from previous drug-level studies because the testing technology has improved and become better at detecting lower drug levels. In addition, the make-up of test subjects in the Ohio study was different than that of other studies. In the past, most researchers that looked at drug levels studied grazing or stalled animals, basically “pets,” she said, rather than performance

horses. In addition, the studies did not look at what happens when the drugs are injected into multiple joints, which is closer to a real-life situation.

“Our job was to look at this in athletes,” she said.

The second finding was that as the amount of methylprednisolone increased in the blood, the horse stopped making the natural steroid, hydrocortisone. “When you give a steroid of any kind, it causes an effect in the body that shuts down the natural hormone. When you give this drug in the joint or muscle, the body says there is a lot of circulating steroid, so I don’t have to produce hydrocortisone,” she said.

And this finding may change the way the USEF tests for these medications.

“They wanted us to prove that this method of screening for hydrocortisone suppression would be a good method for screening.

They had observed that when they tested for corticosteroid use, the hydrocortisone was low. Our study was the first one that correlated it

very well to the level of drug. So, when the drug was at a peak the hydrocortisone suppression was at a peak,” she said.

Veterinarians have about 10 different steroid products they can administer, so the federation has to test for each of these drugs, where screening for hydrocortisone suppression would only require one test. If it is positive that horse could be tested further.

This does not mean that veterinarians cannot give performance horses necessary medication, but they must fill out a medications form and submit it to the federation before the horse is tested at the event, she said.

“If there is a therapeutic reason, a sore joint, a problem with the joint, and you want to reduce the joint pain and inflammation, and it is in the best interest of the horse to have an anti-inflammatory, then it is acceptable to use them, but fill out the appropriate paperwork. The USEF is not interested in penalizing these people, they just want disclosure.”

As an aside, Bertone said that some veterinarians worry that hydrocortisone suppression would have health implications, but she said short-term use does not bear that out. “If you kept them on steroids for a long period, you might increase the risk of infections and other issues, just as can occur in people. But a single dose in a horse, to my knowledge, has not been associated with any long-term problems.”

When a man-made steroid is given, the natural steroid decreases, she explained, but once it is cleared, the body begins manufacturing the natural steroid again.

“Veterinarians need to use their medical judgment when using these drugs in joints, but they should recognize that they will be detected in a higher level and maybe for longer than the guidelines suggest. We had one individual horse — now it was only one horse — but still, it showed corticosteroid use at 56 days after the injection was given. So, individual horses may be out of the range of that guideline,” she said.

MeV ModernEquineVet.com | December 2012

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news notes

WSU/USDA scientist creates test, treatment for piroplasmosis When investigators were asked to investigate a rare but deadly outbreak in South Texas in 2009, they ended up developing a diagnostic test and a treatment for piroplasmosis.

The outbreak occurred at a large 825,000-acre family-owned estate that stretches across four counties. One horse had tested positive for the disease when the federal government first alerted Don Knowles, DVM, PhD, DACVP, Washington State University and the Department of Agriculture veterinary scien-

“If a horse dies of piroplasmosis, anemia is often the cause,” said Knowles, who is a professor of microbiology and pathology at WSU’s veterinary college. “It’s a progressive process and a miserable way for an animal to die.”

Before the outbreak in 2009, no standard treatment existed. If a horse tested positive for piroplasmosis, the owner had three government-mandated options to keep the disease from spreading: euthanize, quarantine or ship the horse out of country. These were not options that appealed to the folks at the ranch.

Photo courtesy of USDA, ARS, Animal Disease Research Unit

Real-world experience

A stained blood smear showing a red blood cell parasitized by Theileria equi.

tist. A few days later, it was a dozen; then four dozen.

“The number just kept going up,” Knowles said.

“This kind of outbreak had never been seen in this country before.” At the request of federal officials, Knowles investigated the outbreak and diagnosed piroplasmosis, or equine tick fever. The causative agents Babesia caballi and Theileria equi parasites are transmitted through a tick bite. Similar to malarial parasites that infect people, these pear-shaped parasites travel through the horse's circulatory system, proliferating and destroying red blood cells.

No treatment, painful options

Many infected horses exhibit little more than coldlike symptoms, but in regions where piroplasmosis is uncommon, such as in the United States, horses have no natural immunity. Unimpeded, the disease causes clinical signs like fever, anorexia and anemia.

Because the test sometimes gave false negatives, Knowles was asked to develop a more reliable diagnostic test and a standardized treatment to kill the parasites. Most of the work on this disease had been done in a laboratory, so this outbreak provided a realworld case.

The horses were treated with high-doses of imidocarb dipropionate, a drug used to treat certain cattle diseases, and it succeeded in eradicating the parasites.

Knowles and his colleagues also identified a new vector, the cayenne tick, and according to a paper in Emerging Infectious Diseases, it is the predominant carrier of the disease.

“Prior to that outbreak, we knew of two tick species capable of transmitting the disease. There, we discovered a third,” said Knowles.

It's likely a cayenne tick bit an infected horse years before the outbreak, drawing parasites in through its blood meal then moving on, infecting other horses, said entomologist Glen Scoles who, after the outbreak, proved that the cayenne species was involved.

This outbreak could have coincided with climate factors that increased the number of ticks, according to Scoles, research entomologist at the Animal Disease Research Unit, Agricultural Research Service, USDA, in Pullman, Wash.

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For more information: Scoles GA, Hutcheson HJ, Schlater JL, et al. Equine piroplasmosis associated with Amblyomma cajennense ticks, Texas, USA. Emerg Infect Dis [serial on the Internet]. 2011 Oct [date cited]. http://dx.doi.org/10.3201/eid1710.101182 14

December 2012 | ModernEquineVet.com

Ann Dwyer, G. Kent Carter sworn in to Lead AAEP Ann Dwyer, DVM, co-owner of Genesee Valley Equine Clinic in Scottsville, N.Y., was sworn in as president of the American Association of Equine Practitioners (AAEP) at the association’s 58th Annual Convention in Anaheim, Calif.

Renowned for her expertise in equine ophthalmology, Dwyer has been an active advocate for the horse and a steady source of service and leadership since joining the AAEP in 1984.

Dwyer was hired as an associate at Genesee Valley Equine Clinic after graduation from Cornell University College of Veterinary Medicine and purchased the practice from AAEP past president Dr. Bob Pearson in 1995.

sis, Nominating and Executive Director Review Committees. She has participated in the Governance Review, Bureau of Land Management Wild Horse and Bureau, and Educational Summit task forces. She represented District 1 on the board of directors from 2006 to 2008 and joined the Executive Committee in 2010. She was honored by her clients with the AAEP’s “My Vet Matters” recognition in 2005.

In related news, G. Kent Carter, DVM, MS, DACVIM, professor and chief of medicine at Texas A&M University, was named 2013 vice president. With this appointment, Carter will assume the role of AAEP president in 2015.

Ann Dwyer, DVM

G. Kent Carter, DVM, MS, DACVIM

She added a full-service equine clinic to the practice in 1997 and brought on practice co-owner Dr. Amy Leibeck in 2001.

In 1988, Dwyer was invited to attend human medical rounds at the University of Rochester Flaum Eye Institute. She has published four book chapters on equine eye disease, including recurrent uveitis and the management of blind horses. Dwyer chaired the AAEP’s Focus on Ophthalmology meeting in 2009 and was instrumental in the planning of the Focus on Ophthalmology meeting in 2012. She serves as a reviewer for Equine Veterinary Ophthalmology and Equine Veterinary Journal. She was awarded a research grant from the American Society of Veterinary Ophthalmology in 1994 and named an Honorary Diplomate of the American College of Veterinary Ophthalmology in 2011.

Dwyer has served on the AAEP’s Problems Analy-

Carter entered private practice in Reno, Nev., after graduating from Colorado State University College of Veterinary Medicine in 1979. He completed a residency in large animal medicine at Texas A&M University in 1982. After two years as a faculty member at Purdue University, he became board certified in internal medicine. In 1984, Carter joined the faculty of Texas A&M University College of Veterinary Medicine and Biomedical Sciences.

For the past 20 years, Carter has collaborated with farriers to resolve equine hoof disorders and lameness.

An AAEP member since 1982, Carter has served on the Abstract Review, Leadership Development, Infectious Disease, Nominating and Student Relations Committees, as well as the Bureau of Land Management Task Force. He was a representative on the AAEP board of directors from 2006-2007. MeV ModernEquineVet.com | December 2012

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technician update

Immune response is critical to control influenza Researchers found that innate and adaptive responses of the immune system play an important role in helping a horse control equine influenza virus (EIV) infection.

Equine influenza virus (EIV) is one of the most common respiratory tract infections in horses.

It can be found in horses worldwide, with the notable exceptions of New Zealand and Iceland, according to the American Association of Equine Practitioners (AAEP). The virus does not circu-

late constantly even among large groups of horses, but is introduced sporadically to a herd by an infected horse, according to the AAEP. Isolation is a good defense. Infection can be avoided by segregating new arrivals for at least 14 days. Vaccination is also a good idea, but horses need to be vaccinated before they are ex-

A schematic representation of equine influenza virus.

Source: PLoS Computational Biology

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EIV Vaccination Schedule Adult horses, previously vaccinated: Mature performance, show, or pleasure horses constantly at risk of exposure should be revaccinated at 6-month intervals.

Other adult horses could be vaccinated as infrequently as once a year.

Adult horses, unvaccinated or having an unknown vaccination history: Either one dose of the MLV intranasal vaccine or a 2-dose series of canary pox vector vaccine at a 4- to 6-week interval (revaccinate semi-annually) or a primary series of 3 doses of the inactivated-virus vaccines is recommended. The ideal intervals between these vaccinations are three to four weeks between the first and the second vaccination, followed by an interval ideally as long as three to six months before the third vaccination. This regimen generally induces higher and more persistent antibody titers than those induced by use of the previously recommended 2-dose initial series.

Subsequent revaccination should be at intervals of 6 to 12 months, depending on the age of the horse as well as the degree and duration of risk of acquiring infection.

Pregnant broodmares, previously vaccinated: Vaccinate 4 to 6 weeks before foaling using an inactivated-virus vaccine or the canary pox vectored vaccine.

Pregnant broodmares, unvaccinated or having an unknown vaccination history: Use a 3-dose series of the inactivated-virus vaccines, with the second dose administered 4 to 6 weeks after the first dose and the third dose administered 4 to 6 weeks pre-partum. With a canary pox vector vaccine, a 2-dose series is recommended with the second dose administered 4 to 6 weeks after the first dose but no later than 4 weeks pre-partum.

Foals of vaccinated mares: Administer either a single dose of the MLV intranasal vaccine (2 doses are recommended if foal is less than 11 months of age, 1st dose at 6 to 7 months of age and second dose at 11 to 12 months of age) or a primary series of 2 doses of canary pox vector vaccine at a 5- week interval or 3 doses of inactivated-virus vaccine beginning at 6 months of age. The recommended intervals between these vaccinations with an inactivated-virus vaccine are 4 to 6 weeks between the first and the second vaccinations. The third dose should be administered between 10 and 12 months of age.

Foals of nonvaccinated mares: Administer either a single dose of the MLV intranasal vaccine (2 doses are recommended if foal is less than 11 months of age, 1st dose at 6 to 7 months of age and second dose at 11 to 12 months of age) or a primary series of 2 doses of canary pox vector vaccine at a 5-week interval or 3 doses of inactivated virus vaccine at 6 months of age (see above), unless there is an unusual threat that recommends earlier vaccination. Because some maternal anti-influenza antibody is still likely to be present, a complete series of primary vaccinations should still be given after 6 months of age.

ModernEquineVet.com | December 2012

OKSun /ShutterStock

Source: AAEP website. See the AAEP Infection Control Guideline for Influenza here http://www. aaep.org/pdfs/control_guidelines/Influenza%20guidelines.pdf

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technician update

posed to the virus. All horses should be vaccinated against EIV, unless they live in a closed and isolated facility, according to the AAEP. This airborne infection is highly contagious and spreads rapidly when coughing horses disperse aerosolized droplets.

Many factors affect the infection and clinical signs, including the horse's degree of existing immunity.

mune responses to study the dynamics of EIV. In the study, the researchers challenged 6 unvaccinated ponies with equine influenza virus and collected nasal secretions for 10 days after the challenge. They also took blood samples for five days after the challenge.

They found that the viral load in all of the ponies increased rapidly and peaked

Equine Influenza Vaccination

3 types of equine influenza virus vaccine are marketed in the United States:

VICTOR TORRES /ShutterStock

• Inactivated vaccines • Modified-live (MLV) coldadapted equine influenza / A2 vaccine • Canary pox vector vaccine

Some horses can have a subclinical infection and still shed virus.

Although most infected patients with intact immune systems can clear the virus and recover without serious complications, the researchers in the current study wanted to characterize the biological factors responsible for this process. They developed mathematical models that included both innate and adaptive im-

at day 2, although there was a wide variation in the peak levels. After peaking, the viral load rapidly declined. In addition, all the ponies experienced a viral plateau, but some ponies experienced a minor, but obvious, second peak, according to the study that appeared in the open access journal, PLOS Computational Biology.

Eventually the viral load declined in all of the horses and the infection resolved.

By comparing modeling predictions with experimental data, researchers examined the relative roles of availability of target cells (cells susceptible to infection), as well as, innate and adaptive immune responses in controlling the virus.

Two-part innate response

The research showed that the first rapid viral decline and subsequent second viral peak can be attributed to a two-part innate immune response generated by natural killer cells and interferon, which are proteins released by the body in response to the presence of pathogens. The second peak comes about because as the viral level falls, the immune response also falls allowing the virus the opportunity to grow back before the adaptive immune molecules ultimately clear the infection.

The adaptive immune response provides the needed response to clear the virus.

The data analyzed were from equine influenza virus infection in horses. However, similar viral kinetic profiles have been observed in a person's reaction to influenza virus infection. The researchers concluded that the study can be used to explain the viral and interferon kinetics observed during a typical human influenza virus infection, once again demonstrating the One Health concept.

MeV

For more information: Kasia A. Pawelek, Giao T. Huynh, Michelle Quinlivan, Ann Cullinane, Libin Rong, Alan S. Perelson. Modeling Within-Host Dynamics of Influenza Virus Infection Including Immune Responses. PLoS Computational Biology, 2012; 8 (6): e1002588 DOI: 10.1371/journal.pcbi.1002588 http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1002588 18

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feedbag

Putting on a few extra pounds? Maybe A recent study found that more than 50% of the horses studied were overweight or obese. Craig D. Thatcher, DVM, MS, PhD, DACVN, said that the problem is probably worse than anyone thought.

Unfortunately, there is not enough data about the problem. A 1998 USDA National Animal Health Monitoring System study estimated that about

1.5% of the US horse population was overweight or obese. In a later study, NAHMS increased the estimate to 3.4% were overweight or obese. However, these estimates were based on owner estimates, instead of objective measurements, according to Thatcher, who is interim associate executive vice provost and professor at Arizona State University.

In this study, the researchers assessed a random sample of 300 mature, light breed horses from 114 Virginia farms. The assessment was made in the summer. Obesity was determined using a validated body condition scoring system and a combination of other body measurements. They found that 51% of the horses were overweight or obese, which was higher than previously reported.

Since obesity results from overfeeding and lack of exercise, it should come as no surprise the horses were obese, because 54.3% had unlimited access to pasture and some of these horses were receiving additional hay and concentrate/grain, according to Thatcher. Furthermore, 58.3% of the horses received less than 1 hour of exercise per week.

He suggested that veterinarians and veterinary

Recipe for a Fat Horse Give horses unlimited access to pasture Add less than 1 hour of exercise a week Result: A nice fat horse In the study

54.3% 58.3%

of horses had unlimited access to pasture had < 1 hr of exercise a week

Result:

Shutterstock/Anastasija Popova

51.0% 20

December 2012 | ModernEquineVet.com

were overweight or obese

technicians implement measures to identify, treat, and prevent obesity in horses, such as routinely performing body condition scoring and evaluating the feeding and exercise programs of patients.

“Nutritionally balanced feeding programs should be implemented based on the Craig D. Thatcher, horse's body weight, body DVM, MS, PhD, condition score, and amount DACVN and intensity of the exercise program,” Thatcher said.

He suggested that veterinarians and/or equine nutritionists sample their patient’s feeds and have them chemically analyzed to develop a nutritionally balanced feeding program. “Decide what feeds should be feed and how much of each feed the horse should receive daily. Once developed, the feeding program and horse should be monitored over time,” he said.

Risk factors for being overweight or obese in this study included feeding 0-1.4 kg of grain or concentrate a day and being older. Most of the overweight or obese horses were between 9 and 12 years old.

Feeding hay was actually protective, he said.

Many of the horses received the grain and concentrate as a treat in addition to the calorie rich pasture, the researchers noted, increasing their risk.

Whether it is people, pets or horses, overcoming the epidemic of obesity won't be easy, but it should start with a conversation with owners about the horse. Just as obesity leads to a host of human diseases, obese horses are at risk for problems, such as hyperinsulinemia and laminitis, he reminded.

A study in Scotland showed that horse owners generally underestimate how fat their horses are, which indicated the poor ability they have to accurately assess body condition. They need their veterinarian's help to keep their pets nutritionally healthy.

Some owners are also concerned that horses that

“

Nutritionally balanced feeding programs should be implemented based on the horses body weight, body condition score, and amount and intensity of the

”

exercise program.

aren't grazing all day will have behavior problems, but Thatcher said that a horse that is exercised and fed appropriately should not be a behavior concern.

Thatcher said his study had several limitations.

Primarily, the horses were analyzed in the summer when they had access to high-quality pasture.

They might lose a little weight in the winter. He said more studies are needed in different regions and different times of year to really understand the extent of the problem.

MeV

Thatcher CD, Pleasant RS, Goer RJ, Elvinger F. Prevalence of overconditioning in mature horses in southwest Virginia during the summer. J Vet Intern Med. 2012 Sep 4. doi: 10.1111/j.19391676.2012.00995.x. [Epub ahead of print] http://www.ncbi.nlm.nih.gov/pubmed/22946995

By Dr. Robert M. Miller

For more information:

Dr. Miller’s books and videos are available for sale at www.robertmmiller.com ModernEquineVet.com | December 2012

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finish line

Be prepared New Jersey Gov. Chris Christy is calling Hurricane Sandy "New Jersey's Katrina," and it is a fair comparison, except I think the government response was a heck of a lot better here than after Katrina.

Many New Jerseyans won't be back into their homes for many months, and there is a lot of debate about whether the shore area will be ready for the 2013 beach season, which would cost this state a lot of revenue. And several equine veterinarians have lost clients who no longer have stables!

Around Thanksgiving, the Christie administration estimated the damages at about $29.4 billion.

The governor plans to refine that estimate in the coming days, i.e., he thinks it's going to cost more.

The preliminary cost estimate is inclusive of aid received to date and anticipated from federal sources including FEMA and the Small Business Administration. The estimate will likely be refined further to consider and include the long-term impact on the next tourism season, shifts in population, impact on real estate values and other factors, the state website said.

“This preliminary number is based on the best available data, field observations and geographical mapping, and supported by expert advice from my Cabinet commissioners and an outside consulting company,” Christie said on the state website. “In

a short period, we put together a comprehensive and responsible estimate, which may increase in the weeks ahead, and I stand ready to work with our Congressional delegation and the Obama Administration to get the funding support New Jersey expects and deserves in the aftermath of this catastrophe.

“We will continue to provide immediate relief for our citizens who were struck hard by Sandy,” the Governor continued. “But be assured, I will spare no effort and waste no time to rebuild and restore our tourism industry, our transportation and utilities infrastructure and the lives of our citizens for the long term.”

I live in New Jersey, but luckily not near any bodies of water, and because our home is relatively new, not near any old trees, so we came through the storm pretty well. We lost our power for four days and had to throw away some groceries, but all in all, we were among the very lucky.

My dogs' veterinarian was not so lucky. She practices in a small two-doctor clinic that is attached to the owner's home. They were without power for closer to 10 days. That means they could not practice for almost two weeks.

While such a devastating natural disaster is so fresh in our minds, I thought it would be a good

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idea to talk about emergency preparedness.

Be prepared and educate

Today's equine veterinarian has to be prepared for any disaster, but he or she should assure that clients know what to do, too. You are the one who can best treat the injuries that might occur as a result of a disaster, and you understand the stress a horse might experience in a disaster, as well as the logistical factors involved in evacuating it.

Take care of yourself first. Make sure your practice insurance coverage is sufficient to handle all the loses you might suffer in a disaster.

Buy a generator or two to keep your vaccines and medications refrigerated if needed.

Make sure your staff knows what to do to prepare for an emergency. Make sure your home and family are covered, and they know what to do, too.

Establish disaster and emergency plans

Print out a hard copy of any important phone numbers and documents and keep this copy with your emergency preparedness evacuation kit.

It might be difficult to search an internet database when the power is out. My utility and local media kept advising me to go online for information, but with my electricity out for four days, I had no cable, i.e. Internet access. Connecting to the Internet drains a cell phone's battery quickly, and it might be difficult to recharge it. (Thanks to Wal-Mart who created free charging stations for customers to use.)

Take care of your clients and patients next.

Teach clients the importance of emergency preparedness and help them establish a disaster and emergency response plan.

Here are recommendations from FEMA: • Ensure all animals have some form of identification.

• Evacuate animals whenever possible. Map

out primary and secondary routes in advance.

• Make available vehicles and trailers needed for transporting and supporting each type of animal. Also make available experienced handlers and drivers. Note: It is best to allow animals a chance to become accustomed to vehicular travel so they are less frightened and easier to move.

• Ensure destinations have food, water, veterinary care and handling equipment.

• If evacuation is not possible, animal owners must decide whether to move large animals to shelter or turn them outside.

And for heaven's sake, if the governor of the state tells you to get the heck out of Dodge — Get the heck out of Dodge!

Evacuate.

Don't sit around and wait for the water to lap up against your doorstep before you leave, either.

And if it's not safe for you, it probably is not safe for your animals, either. Don't leave them behind. Many of the shore communities could not get back to their homes for over a week.

Find a safe and secure place to put them to wait out the storm. That might mean making arrangements with another horse owner long before the storm occurs or boarding horses, dogs and cats in another state.

Remember that your stuff is just that — stuff.

It can be replaced, and buildings can be rebuilt.

It is your family and your animals that are important. Be smart and stay safe.

The American Association of Equine Practitioners has a lot of great information on its website about disaster preparedness for both the equine veterinarian and horse owners. http://www.aaep.org/emergency_prep.htm Marie Rosenthal, MS Editor The Modern Equine Vet

Here are a few more links about emergency preparedness that might be useful: AVMA: https://www.avma.org/kb/resources/reference/disaster/pages/default.aspx FEMA: http://www.ready.gov/animals National Weather Service: http://www.nhc.noaa.gov/ USDA: http://www.aphis.usda.gov/animal_health/emrs/ National Center for Animal Health Emergency Management: http://www.aphis.usda.gov/vs/ep/hpai-response.html

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