elbow grease required for...

Elbow Grease Required for Disinfection

Fescue Toxicosis in Nonpregnant Horses

Toxicosis, p. 5

Tall fescue (Lolium arundina-ceum) is a perennial grass that is

adapted to much of the eastern half of the United States, and is widespread in the central Ohio valley, including Ken-tucky. Much of the tall fescue contains a fungus, called an endophyte, which, together with the fescue plant, produc-es chemicals called ergot alkaloids that can be harmful to grazing animals. The best known of these ergot alkaloids is ergovaline.

Fescue toxicosis in horses is most frequently associated with hormonal changes in late gestation mares, where

gestation lengths may be extended be-yond the expected due dates. It is also associated with thickened placentas and abnormal placental separation when birth occurs, as well as with dys-tocia and agalactia (lack of milk pro-duction by the dam).

In cattle, the most frequently reported signs of fescue toxicosis are associated with constriction of the blood vessels. This may result in cattle overheating in the summer because they cannot dis-sipate heat effectively, and sometimes causes signs of gangrene in the winter when there is insufficient blood flow to

the hooves or tail switch. In cattle, fes-cue toxicosis is also associated with low average daily gain, poor growth rates, and lowered fertility. Reports in the lit-erature of whether grazing endophyte-infected fescue can cause poor growth rates in young horses or reduced perfor-mance or fertility rates in horses are inconsistent, and mechanisms which might contribute to these effects have not been investigated. Therefore, several years ago,

Cleaning out the garage. Sorting through all the “stuff ” in the attic.

Shampooing the en-tire house’s carpet-ing. What could be a worse assignment? All of those tasks require lots of time, hard work, and are few people’s enter-tainment-of-choice for a weekend. Most horse people would rather saddle soap every saddle and piece of leather they own, or even wash and wax the horse trailer.

There is one horse-related duty that ranks right up there (on most people’s scale) with the above dreaded assign-ments--cleaning and disinfecting stalls. Who wants to strip totally every stall in a

barn, wash, disinfect, and re-bed them all? That is a lot of labor most people would

gladly put off for a nice trail ride. Plus, it’s not really neces-sary, or is it? Put yourself in these situ-ations:

You are the owner of a b o a r d i n g stable with 35 horses,

primarily pleasure horses used for trail riding. After some horses return from a weekend ride, two horses develop pro-fuse diarrhea. The veterinarian suspects salmonellosis and two days later con-firms the diagnosis. How do you protect the other horses on the farm, including

your own?As manager and resident trainer at a

hunter/jumper instructional school, you have horses and riders from throughout the country come to your facility to train. One day, a jumper develops a snotty nose and spikes a temperature. Within two days, abscesses start to form under the horse’s jaw--diagnosis, strangles. What will this do to your business and reputa-tion?

You own one horse and proudly com-pete at county fairs and local horse shows. Besides vaccinations, how do you keep your horse healthy when you don’t know what was in that stall on the show grounds where you have to put your horse?

Disease outbreaks are dangerous to the health of your horses, and can be eco-nomically disastrous for your business and reputation. They can be personally

Disinfection, p. 3

G L U C K E Q U I N ER e s e a r c h & S e r v i c e R e p o r t

Spring 2014Volume VI, Issue I

The best way to slow and stop the infectious chain of events is to kill the organism before it can

contaminate another horse and cause disease.

Gluck Equine Research Foundation Spring 2014 2

GLUCK EQUINE RESEARCH FOUNDATION

Dr. Ed Squires Executive Director Mrs. Jenny EvansMarketing and Promotion Specialist Senior Gluck Equine Research Foundation 108 Gluck Equine Research Center Lexington, KY 40546-0099 Phone: (859) 218-1089 Fax: (859) 257-8542 E-mail: [email protected] [email protected]

Website: http://ca.uky.edu/gluck

Cover photo by Erin Morgan

The mission of the Gluck Equine Research Center is scientific discovery, education and dissemination of

knowledge for the benefit of the health and well-being of horses.

The UK Gluck Equine Research & Service Report is pro-duced by UKGERF and the Department of Veterinary Sci-ence. It is published twice a year on behalf of all equine researchers and veterinarians and others in the horse industry who are committed to the continued improve-ments in equine research and technology.

Research material is meant to be shared. However, materials are copyrighted and require reprint permission from UKGERF.

UNIVERSITY OF KENTUCKY GLUCK EQUINE RESEARCH FOUNDATION

Case Clay, Chair

Art Zubrod, Vice Chair Dr. Eli Capilouto, President

Dr. Christine Riordan, Vice PresidentDr. Nancy Cox, Secretary

Mrs. Angela Martin, Treasurer

Michael BanahanMark Bellissimo

Benny Bell Williams Dr. Stuart Brown

Dr. Rolf Embertson William S. Farish, Jr.

Tom GoncharoffThomas Grossman

Eric HamelbackDr. Robert E. Holland, Jr. G. Watts Humphrey, Jr.

William Lynn Jones Lisa Lourie

Michael MeuserDr. Stephen ReedDan Rosenberg

Dermot RyanDr. Robert Stout

William “Bill” W. Thomason, Jr. Dr. Mats Troedsson

Ron WallaceF. E. “Butch” Wise

Dr. Naoya Yoshida

MASTHEADBOARD OF D IRECTORS


Infectiou

s Diseases

devastating when the disease prevents you from competing in a long-awaited event and causes significant financial strain.

Why disinfect? Isn’t vaccination enough? If only it were that easy!

First, no vaccine is 100% effective. Sec-ond, there are many more disease-caus-ing organisms (pathogens) than there are vaccines. The table at right shows only some of the known pathogens of horses, and indicates those that commonly cause outbreaks of disease, or multiple cases on one farm. Many Gram-negative bacteria are present in feces and bedding, and are common causes of septicemia, which can be deadly to foals. These bacteria also can cause localized infections in areas such as eyes and joints of adult horses.

Of course, there are always those “mys-tery microbes” in the environment that cause respiratory disease, diarrhea, limb swelling, and other conditions that veter-inarians recognize as being caused by in-fectious agents, but are unable to find the specific cause. They can’t find the exact cause usually due to limitations in cur-rent diagnostic tests. New bacteria and viruses are being found regularly with the advent of new microscopes and cul-turing methods. In 10 years, the list in the table will be increased—which is good since the more we know about the “bad guys,” the more we can do to fight them and protect the health of horses.

Tough Bugs Of the known common equine patho-

gens, clostridial organisms are the most difficult to kill because they are spore-forming bacteria found in feces and soil (organic matter). Clostridial diseases such as tetanus and botulism are indi-vidual animal diseases, and outbreaks are not common.

Of the contagious disease-causing pathogens in the table, rotavirus is the most difficult to kill due to its being a “non-enveloped” virus. The lipid enve-lope of other viruses is disrupted by a variety of detergents and disinfectants, enabling the virus to be killed.

Salmonella spp. also are difficult to kill, requiring thorough cleaning and strin-gent disinfection.

The follwing is an example of its resil-iency: In one Swedish study, viable Sal-

monella cultures were obtained from dried cattle feces removed from a barn that had been abandoned for six years.

Rotavirus can remain infective after more than nine months.

Rhodococcus equi lives in the environ-ment for years.

So, by identifying the horse’s bacterio-logic and virologic enemies, and know-ing that vaccination is useful, but not 100% effective, often the only way to pre-vent and control outbreaks of disease is through management and disinfection of the horse’s environment.

Notice: We did not say we are steriliz-ing or sanitizing the stalls. Rather, we are killing the pathogens as best we can with chemicals produced specifically for that use.

In the midst of a salmonellosis, stran-gles, or rotavirus outbreak, the best way to slow and stop the infectious chain of events is to kill the organism before it can contaminate another horse and cause dis-ease.

What are we going to disinfect? This actually is an important question, and its answer dictates the types of disinfectants appropriate for use.

Many disinfectant labels state they are

for use in hospitals, nursing homes, and health care facilities, with many people’s natural conclusion being, “If it is good enough to use in human hospitals, surely it is good enough to use in my barn.”

But, what surfaces are being disinfect-ed in hospitals? Stainless steel, glass, ce-ramic, linoleum, and solid plastics. Now, who has ever seen a horse stall made of glass and ceramic? Hospital surfaces are primarily nonporous and easily cleaned prior to disinfection.

Horse stalls are primarily made of wood or concrete block and might have some metal fittings and fixtures. Raw wood and unpainted concrete blocks are very porous and can trap and hide pathogens from disinfectants. This porous nature also makes the surfaces difficult to clean adequately.

There is a solution to this problem. Raw wood has to be cleaned of all debris. Holes and knots are filled with caulking or plas-tic wood, then a marine-quality varnish or polyurethane is applied to make the wood as nonporous as possible. Concrete block also can be cleaned and covered with two coats of enamel paint to make the surfaces easy to clean and disinfect.

Disinfection, continued

Disinfection, p. 4

Common Equine PathogensBacteria Pathogen Classification Diseases Salmonella spp.* Gram-negative Salmonellosis, septicemia,

diarrheaStreptococcus equi* Gram-positive StranglesRhodococcus equi* Gram-positive Pneumonia, diarrhea,

other infectionsEscherichia coli Gram-negative SepticemiaActinobacillus spp. Gram-negative SepticemiaPseudomonas spp. Gram-negative SepticemiaKlebsiella spp. Gram-negative SepticemiaEneterobacter spp. Gram-negative SepticemiaClostridium spp. Gram-positive,

spore-formingTetanus, botulism, diarrhea, sudden death

Virus Pathogen Classification DiseasesRotavirus* Non-enveloped virus Foal diarrheaInfluenza* Enveloped virus Respiratory diseaseHerpesvirus* Enveloped virus Respiratory disease,

abortion, neurologic diseaseEquine arteritis virus Enveloped virus Abortion, systemic disease

*cause of disease outbreaks potentially involving large numbers of animals


Disinfection, continued

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What about floors?Dirt, sand, or clay floors cannot be dis-

infected because they are soil (see disin-fecting dirt sidebar at left). Removable rubber mats can hide many microorgan-isms beneath them, causing an increas-ing stench if not routinely removed and cleaned. Certain rubber mats can be placed and sealed along all seams and glued to the solid floor beneath, making them an excellent surface for the horse and stall cleaner. Asphalt or concrete flooring easily can be cleaned and disin-fected, but can be hard on the horse’s legs.

So, our first objective is to have as many nonporous surfaces in a stall as possible.

Disinfectant Considerations Hundreds of disinfectants are available

commercially. How is anyone to know which ones are the best?

First, we know what major pathogens we need to kill, and we know the types of surfaces there are on horse farms . Second, we need to recognize where the pathogens are residing--in organic mat-ter. Salmonella and rotavirus are in feces; S. equi is in nasal and abscess discharges; influenza virus and herpesvirus are in re-spiratory droplets. All of these materials (feces and discharges) are considered or-ganic matter, which readily can inactivate some of the most potent disinfectants.

The situation is much different in a lab-oratory where a pure culture of bacteria is on glass or stainless steel. A disinfec-tant doesn’t have to deal with any organic matter--it just kills the bacteria on the nonporous surface. As we know, the situ-ation is quite different in a horse stall!

In the real world, a disinfectant must be able to work in the presence of organic matter on contaminated surfaces. It must be germicidal against the pathogens en-countered, and it must be biodegradable, cost effective, and relatively safe for hu-mans and animals.

The disinfectant also must be able to kill pathogens in the water you have avail-able. Water hardness is an indication of calcium and magnesium in the water. Those minerals can adversely affect the potency of a disinfectant.

Many disinfectants are labeled as to their effectiveness in hard water, such as, “Proven effective in 400 ppm water hard-ness.” The abbreviation “ppm” means

parts per million. This little fact is mean-ingless unless you know the hardness of the water on the farm. If you use city wa-ter, check with the water company on the average water hardness; if you have well water, contact the county extension ser-vice on how to get water samples tested. If you have used a disinfectant in your barn that only works to 400 ppm water hardness and your well water is 550 ppm, you’ve put a lot of money and labor into a cleaning effort that is not effective!

Choices, Choices, Choices So, where do you find a disinfectant

that will work given all these factors? There are many different classes of disin-fectants, including phenols, iodophores (e.g., povidone iodine), hypochlorites (e.g., bleach), chlorhexidine, quaternary ammonium compounds, and others.

Phenolic compounds, recognized by the “-phenol” or “-phenate” at the end of the active ingredient names, will kill rotavirus, Salmonella, R. equi, and other equine pathogens in the presence of or-ganic matter (see disinfectant protocol sidebar above).

Iodophores, such as 10% povidone io-dine, also will kill rotavirus in the pres-ence of organic matter, but usually are used as a surgical scrub and antiseptic rather than a stall disinfectant.

Although bleach commonly is used in human hospitals and laboratories, it is readily inactivated in the presence of or-ganic matter and, therefore, is not suit-

Disinfecting Pastures and Dirt FloorsWith outbreaks of salmonellosis, strangles, rotavirus, and other diseases, the ques-

tion often arises, “How do we disinfect the pastures?” There is no safe way to kill equine pathogens in soil. In fact, the soil contains its own set of normal flora (and even earthworms) that keep the soil and the pastures healthy. Killing these soil orgain-isms would be extremely detrimental to pastures of chemical disinfectants were used.

Some viruses, like herpesvirus, cannot live for long periods of time outside of living cells, and are susceptible to Mother Nature’s “disinfectants” of sunshine, drying, and wind. Other pathogens, like Clostridium spp. and rotavirus are extremely resistant to environmental conditions.

So what are you to do?Remove feces from dirt lots, chain harrow pastures to expose manure to air, reseed

bare areas in pastures, and practice good pasture management. Also, avoid overpopu-lating pastures.

For sand, dirt, or clay stall floors, remove as much bedding and feces as possible to allow the area to dry. Lime (calcium carbonate) can be sprinkled on floors of fans can be used to speed the drying process. In extreme situations, such as a stall that is heavily contaminated with Salmonella, the top 6-12 inches of soil might have to be removed and replaced with fresh material.

--Dr. Roberta Dwyer

able for use as the primary disinfectant on the farm.

Chlorhexidine does not kill rotavirus, but is useful for disinfecting surgical in-struments and is used as an antiseptic.

Quaternary ammonium compounds, recognized by “-ammonium chloride” at the end of the active ingredient name, are inactivated in the presence of organic matter and do not kill rotavirus.

Pine oil, often used for its fragrant smell, is not useful as a disinfectant.

Keep in mind that disinfectants that are inactivated in the presence of organic matter might be perfectly useful for the countertops in the tack stall, cleaning out the refrigerator, and for other areas that are not heavily contaminated. How-ever, for use in stalls, horse trailers, and aisleways that have heavy traffic and high levels of contamination, phenolic com-pounds work very well.

Two phenolic disinfectants with greater than 20% active ingredients are approved for use in Kentucky equine quarantine facilities: Tek-Trol (Bio-Tek Industries, Inc.) and 1-Stroke Environ (STERIS Corp.). Many other phenolic compounds are on the market.

Whenever you are comparing prod-ucts, be sure to read the label for water hardness testing, organic load testing, biodegradability, proven efficacy against equine pathogens, dilution, and cost.

--Dr. Roberta Dwyer


the laboratory of Karen McDowell, PhD, as-sociate professor at the University of Ken-tucky Gluck Equine Research Center, un-dertook some experi-ments to determine if endophyte-infected fescue caused vasocon-striction (constriction of the blood ves-sels) in horses, similar to what it does in cattle.

McDowell, along with Laurie Law-rence, PhD, professor in the Depart-ment of Animal and Food Sciences at UK, fed horses ground fescue seed that contained either ergovaline and associated ergot alkaloids, or did not contain the alkaloids. They measured blood flow in, and the diameter of, the palmar artery in the left foreleg of each horse, just above the fetlock joint, using Doppler ultrasonography. They found a significant constriction of that artery in animals consuming fescue seed con-taining the alkaloids but not in animals consuming alkaloid free seed (Figure 1). This was the first known report of endophyte-infected fescue causing va-soconstriction in horses consuming it, and the results were published in the Journal of Animal Science.

Next, McDowell’s laboratory set out to investigate if mares consuming

Toxicosis, continued

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Three images of the palmar artery of same horse before (A) or during (B and C) the treatment of adding endophyte infected fescue seed to the diet. During the treatment period the artery would sometimes appear as in B (circled) or as in C, both signifi-cantly constricted compared to A.

endophyte-infected fescue seed had altered blood flow to the ovaries. This experiment was part of the Master of Science Degree of Drew Hestad, MS, who is currently in veterinary school at Auburn University. Mares were fed fescue seed which contained ergovaline and associated alkaloids, or fescue seed that was free of the alkaloids. Each of 12 mares received non-infected seed for one complete estrous cycle and infected seed for another complete estrous cycle. Mares receiving the infected seed had constriction of the palmar artery, pal-mar vein, and importantly, reduced blood flow in the corpus luteum, the structure on the ovary that produces progesterone. This was the first report of infected fescue causing reduced blood flow to the ovaries in mares.

This spring, McDowell, along with Glen Aiken, PhD, from the USDA For-age Animal Production Unit on the UK campus, and Michael Barrett, PhD, and Tim Phillips, PhD, from the Depart-

ment of Plant and Soil Sciences at UK, will examine va-soconstriction and pregnancy outcomes in pregnant mares grazing fescue grass which contains a novel endophyte. This grass produces alkaloids which give

the grass a competitive advantage over other forage grasses, but not the al-kaloids, such as ergovaline which are harmful to grazing animals.

Although the deleterious health ef-fects of endophyte-infected fescue in mares has previously only been asso-ciated with problems in late gestation, recent work has demonstrated that en-dophyte-infected fescue can cause va-soconstriction in the legs and reduced blood flow to reproductive organs in mares. The significance of these effects on growth, performance, fertility, or other physiological parameters is yet to be determined. However, McDowell believes that the use of Doppler ultra-sonography to monitor the diameter of the palmar artery of horses grazing endophyte-infected tall fescue pastures may provide a convenient and noninva-sive biomarker to determine premoni-tory signs of fescue toxicosis, and is continuing work in this area.

--Dr. Karen J. McDowell

Nutrition’s Role in Enhancing Aging Horses’ Immunity

Over the past century, improve-ments in health care and ad-

vancements in biology, chemistry, and medicine have extended the average lifespan of humans and companion animals, including horses. However, we are now facing new challenges with the paradox of an older population with increased longevity, while confronted with the potential for many years of poor health. A better understanding of the mechanisms leading to a decline in physiologic function with age would provide new predictive biomarkers and potential therapeutic targets.

It has been well-documented that

the aged, i n c l u d i n g horses, have i n c r e a s e d susceptibil-ity to and prolonged r e c o v e r y from infec-tious dis-eases, poor re s p on s e s to vaccina-tion, and i n c r e a s e d

Aging, p. 6Chronic inflammation (inflamm-aging) is a major underlying

condition of many age related diseases in horses.


The first research crowd-funding project at the Uni-

versity of Kentucky raised more than $6,000 for parasitology re-search with more than 50 indi-vidual donors from the United States, Canada, Australia, and several European countries hav-ing contributed.

Martin Nielsen, PhD, DVM, PhD, DEVPC, DACVM, an equine parasitologist, veterinar-ian and assistant professor at the UK Gluck Equine Research Cen-ter, launched the crowdfunding project titled, “Let the germs get the worms:

Testing a novel probiotic compound for treatment of equine parasites,” in Janu-

ary. Nielsen’s crowdfunding proj-ect, which ended on March 10, is possibly the first such effort in the field of veterinary science.

“We are highly grateful for the tremendous support we received. Reaching the first milestone will enable us to test our bacterial product against equine ascarid roundworms under laboratory conditions,” Nielsen said. “Asca-rids are a major problem in foals,

as they have become highly drug-resistant and are the cause of severe

small intestinal impactions.”

First UK Equine Research Crowdfunding Project Raises $6,000

Crowdfunding, p. 7

incidence of various cancers. Further-more, it is now accepted that chronic inflammation (inflamm-aging) is a ma-jor underlying condition of many age related diseases, such as arthrosclerosis, arthritis, cancer, diabetes, osteoporosis, dementia, vascular diseases, obesity, and metabolic syndrome.

In anti-aging research, much atten-tion is focused on nutritional inter-ventions as practical, cost-effective ap-proaches to mitigating this age-related breakdown in immune function. These natural dietary compounds found in a variety of fruits, vegetables, nuts, and seeds are promising candidates in help-ing to combat the effects of aging. They possess broad biological activities: anti-oxidative, anti-inflammatory, detoxi-fication, regulating signaling pathway, and modulation of enzyme activities (see chart to right).

Since aged horses (those 20 years and older) have increased levels of inflam-mation, and treatment with long-term use of non-steroidal anti-inflamma-tory drugs (NSAIDs) such as flunixin meglumine and phenylbutazone can pose health problems, we are interested in nutritional interventions to counter-act this inflamm-aging process.

Flavonoid (quercetin) and polyphe-nolic compounds (curcuminoids, resveratrol, pterostilbene, and hy-droxypterostilbene) were compared to

phenylbutazone and flunixin meglu-mine to determine differences in equine cytokine production in cell culture. White blood cells from aged horses were isolated and incubated overnight with each compound of NSAID at multiple concentrations. Inflammation production was measured when white cells were stimulated.

At varying doses (measured in mi-cromolar units [µM]), each of the compounds and NSAIDs significantly reduced cellular inflammation: cur-cuminoids (20 µM), hydroxypterostil-bene (40 µM), pterostilbene (80 µM), quercetin (160 µM), resveratrol (160 µM), flunixin meglumine (40 µM), and phenylbutazone (>320 µM). Interest-ingly, curcuminoids at a concentration of 20 µM reduced inclmmation to the same level as higher doses of flunixin

Aging, continued

meglumine (40 µM) and phenylbu-tazone (>320 µM). All natural com-pounds outperformed phenylbutazone by being effective at lower doses.

This preliminary research has led into two studies using aged horses to deter-mine if a relationship exists between circulating vitamin and fatty acid levels to systemic inflammation and muscle mass, and if anti-inflammatory supple-mentation affects immune responses to vaccination. These are preliminary steps to identify effective nutritional in-tervention regimens to improve func-tion of the immune system in the aged horse.

--Dr. Amanda Adams This is an excerpt from Equine Disease

Quarterly, funded by underwriters at Lloyd’s, London, brokers, and their Ken-tucky agents.

Natural Dietary Compounds with Anti-Inflammatory MechanismsGroup CompoundCarotenoids Beta-carotene, lycopene, luteinFlavonoids Quercetin, catechin, epigallocatechin-3-O-gallate,

theaflavinIsothiocyanates Sulforaphane, phenethyl, isothiocyanateTerpenoids Limonene, retinoic acidProanthocyanidinsOmega-3 fatty acids Eicosapentaenoic acid, docosahexaenoic acidPolyphenolic compounds

Curcumin, gingerol, resveratrol, pterostilbene

Im

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Dr. Martin Nielsen


Level of Parasite Egg Shedding on Thoroughbred Horse Farms in Central Kentucky

Researchers from the University of Kentucky Gluck Equine Research

Center recently conducted a study on strongyle parasite egg count values in horses on 25 Central Kentucky farms. Data from the study showed the benefit of establishing strongyle egg counts to determine the need for treatment.

The trend for parasite control in hors-es has long been to deworm on a fre-quent basis, although it is well-known that this might lead to widespread drug resistance. Typically, owners treat herds without first performing parasite egg counts to help determine which indi-vidual horses need treatment.

Therefore, the researchers aimed to investigate the strongyle egg count sta-tus on a large number of horses on a regular deworming program, said Gene Lyons, PhD, professor in classical para-sitology at the Gluck Center.

A total of 1,300 mares of various ages participated in the study (most were Thoroughbreds, while the rest were Standardbred and mixed light breeds). The goal was to establish a strongyle egg count profile on each mare based

upon age, number of egg count posi-tives, and level of egg shedding.

“Findings from the study clearly showed the value of performing the EPG (eggs per gram) status on horses. The most important result of this re-search was that the majority of Thor-oughbred and Standardbred mares had no or low egg counts. Since these horses were already on a regular deworming

program, there would be no obvious reason to give them extra treatment,” Lyons said.

Upon reviewing the results of this particular study, the researchers also found:

• The Thoroughbreds had the low-est prevalence of positive egg counts at 32%. The youngest age

Crowdfunding is a relatively new term that describes reach-ing out to the general public, usually through the Internet, to reach a fundraising goal. Suc-cess in reaching the goal often depends on many individu-als making smaller donations through a website. The crowd-funding campaign was host-ed at http://equineparasitol-ogy.ca.uky.edu/. The site is still available and will continue to allow guests to sign up for more information, access videos and educational information and ask Nielsen exclusive questions about parasite control for their horses. Featured videos on the site have been viewed more than 1,500 times since it launched.

Nielsen’s research team is devoted to providing solutions for worm control

Crowdfunding, continued

Parasitology

in horses. Horse parasites, such as small strongyles and large roundworms, are developing increased levels of resis-tance to all available dewormers. No new drugs are being developed for use in horses, so the equine industry needs new reliable treatment alternatives.

Horses on pasture are constantly exposed to different parasites. These can cause disease symp-toms such as colic, diarrhea and weight loss. Foals are particular-ly vulnerable to parasite infec-tion and need special attention in parasite control programs.

“It is our experience that horse owners are very interested in updated information about parasite control and have great concerns about drug resistance,” Nielsen said. “We therefore felt that crowdfunding would be very appropriate for raising funds for research in this area.

The crowdfunding platform allows di-rect interaction with the end users of our research, which is very valuable to us. A good question can inspire us to set up the next research project.”

--Jenny Evans

Egg shedding, p. 8

Dr. Nielsen’s parasitology group with horses in the parasitology herd at UK’s Maine Chance Equine Campus. Pictured are (L to R): Holli Gravatti, research analyst; Emily Rubinson

and Jennifer Bellaw, MS graduate students; and Dr. Nielsen.

The researchers considered management aspects as part of the reason why Thoroughbreds and Standardbreds had lower levels of parasite infection

compared to the smaller group of mixed light breeds.


Egg shedding, continued

Small Strongyles Might be Developing Drug Resistance Against Ivermectin

Early return of parasite eggs in fe-cal samples after ivermectin treat-

ment should be seen as a sign of de-veloping resistance, according to Gene Lyons, PhD, professor in classical para-sitology, and colleagues from UK’s De-partment of Veterinary Science.

Small strongyles (cyathostomes) are the most numerous parasites in the horse and they can cause severe damage when encysted stages merge in large numbers from the intestinal wall. Thus, it is important to treat infected horses with potent and effective drugs used for parasite control, particularly because small strongyles have the ability to de-velop resistance to dewormers. In ad-dition, these parasites naturally have a relatively short life cycle.

Since no new drugs against small strongyles are currently being devel-oped, an effective parasite control pro-gram should aim to prevent further resistance. Previous studies performed by Lyons and others have shown that strongyle eggs are currently return-ing sooner after ivermectin treatment, compared to when the drug was in-troduced about 30 years ago. This has raised concerns about whether it could signal early signs of developing iver-mectin resistance.

Recent studies performed by research-ers at UK have shown that ivermectin resistance is developing in the imma-ture larvae of the small strongyle para-

sites. The horse ingests infective larvae from the pasture that develop into adult egg-laying worms within the bowel. Small strongyles reside in the colon and cecum of the horse and undergo several developmental stages before they begin to shed eggs.

According to Lyons, the purpose of a follow-up study was to obtain further information about the activity of iver-mectin against immature small stron-gyles in four Central Kentucky born and raised weanlings.

The weanlings in the study had not been given a dewormer prior to study, but other horses in the same herd had received ivermectin repeatedly over the course of several years, Lyons said. While the weanlings were housed in stalls, their body weights were mea-sured and each horse received ivermec-tin according to a standard protocol. Worms were then recovered from fe-cal matter collected daily for six days following treatment. The researchers found 12 species of small strongyles parasites after counting and identifying worms.

According to Lyons, the study overall confirmed previous findings.

“Ivermectin efficiency still was 100% against adult parasites, which is good news, but only ranged between 0 and 16% against the immature stages,” he said. “Overall, the efficiency both against adult and immature stages com-bined was in the range of 68%-83%.”

The reason for the early return of strongyle eggs after treatment, Lyons said, is most likely a lowered drug effi-ciency on immature small strongyles in the large intestine of the horse. Interest-ingly, the drug efficiency against imma-ture strongyles was lower in this study compared to a previous study, which may reflect that ivermectin efficiency is declining.

--Shaila Sigsgaard

Par

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group (3-5-year-olds) showed the highest strongyle counts, while the group of 6-10-year-olds and older had lower infection rates.

• 48% of the Standardbreds were positive for strongyle egg count. For both Thoroughbreds and Standardbreds about 60-70% of horses had low egg counts below 200 eggs per gram (EPG).

• In contrast, 77% of the mixed light breed mares were positive for egg count. The infection rates for this group were highest in 3-10-year-

Early return of strongyle eggs (egg reappearance period) can be explained as the interval between an anthelmintic treatment (dewormer) and the time when eggs can be detected in the feces. Early egg return can either be a sign of selection of populations of worms that reproduce faster than the average or resistance to the anthelmintic.

olds and lowest for the older age groups, but significant for all the age groups. More than 37% of the mixed light breed mares had val-ues of more than 500 EPG.

The researchers considered manage-ment aspects as part of the reason why Thoroughbreds and Standardbreds had lower levels of parasite infection com-pared to the smaller group of mixed light breeds.

The mixed light breeds tended to graze on more overpopulated pastures with less intensive management, whereas the Thoroughbreds and Standardbreds

tended to have ample pasture, Lyons said. All breeds were on a routine de-worming schedule, and the research team therefore suggested management efforts could influence strongyle egg counts.

“While our data clearly showed that different horse management systems af-fect the parasitic status of horses, an as-sociation between the breeds of horses and the prevalence of parasite infection could not be established,” Lyons said.

--Shaila Sigsgaard


Using Oxytocin to Suppress Estrus in Mares

Researchers from the Uni-versity of Kentucky Gluck

Equine Research Center evaluated the effectiveness of a hormonal treatment (oxytocin) in prevent-ing mares from showing estrus (heat) for an extended period of time.

Currently, in order to prevent mares from showing estrus an oral hormonal (progesterone) product (ReguMate) must be given every day. This is a labor-intensive and expensive way to suppress estrus. The study investigated a simpler, less-costly approach, which was based on injecting another hor-mone called oxytocin. Earlier studies had shown oxytocin to be effec-tive in suppressing estrus in mares but frequent injections had to be given. The goal of the current project was to de-termine if the number of injections of oxytocin could be decreased and still be effective in suppressing estrus.

“This work is a huge leap forward in unfolding the mechanisms behind the effects of chronic oxytocin treatment in mares,” said Ed Squires, PhD, Dipl. ACT (hon.), professor and executive director of the UK Gluck Equine Re-search Foundation. “Treatment with oxytocin may be one option to pre-vent the mare from going into heat and could be the least costly method of sup-pressing heat in show horses and pos-sibly race horses.”

The normal cycle in the mare is 21 to 22 days long, as measured by counting days be-tween ovulation. The length of time the mare is in heat can vary but is gener-ally four to seven days. Once a mare ovulates a follicle, the corpus luteum (CL) forms on the ovary and produces the hormone progesterone, which pre-vents the mare from coming back into heat for about 14 days. This phase of the mare’s cycle is called diestrus.

While some mares’ behavior is altered very little when they are in heat, others

exhibit signs of heat that may negatively affect performance and lessen their fo-cus. An elevated tail and frequent uri-nation, which are associated with es-trus, are generally undesirable. While these attitude changes might not pose a problem, it could potentially distract and impair a mare’s overall perfor-mance in the show ring or on the race track. Horse handlers, therefore, often prefer to suppress estrus in mares to prevent potential behavioral problems, Squires said.

For the study, mares received oxytocin daily on Days 8 to 10, 8 to 12, or 8 to 14 after ovulation to study the mecha-nisms behind treatment with oxytocin that would result in continual produc-tion of progesterone from the CL on

the ovary. Death of the CL occurs in the absence of pregnancy at the end of di-estrus phase while treatment with oxy-tocin prolongs the period the mare is not in heat. If a mare does not become pregnant, release of prostaglandin (a hormone coming from the uterus) nor-mally causes the CL to die and the mare enters a new cycle. However, several previous studies have confirmed that

administering oxytocin after ovu-lation prolongs the length of time the CL in the mares continues to produce progesterone.

“As research has previously prov-en, we found oxytocin administra-tion when given eight days after ovulation was effective in prevent-ing the corpus luteum on the ovary from dying, and heat-related signs were reduced accordingly in these mares,” Squires said. “However, the oxytocin had to be given for sev-eral days to get this response. We were not able to shorten the num-ber of days oxytocin was given and still have the mare stay out of heat for an extended period of time.”

The researchers also collected tis-sue from the endometrium (the lining of the uterus) to evaluate the cellular changes in the uterus with oxytocin treatments from Days 8 to 14 after ovu-lation.

The study found that administration of oxytocin regulates an enzyme called cyclooxygenase 2, preventing the pro-duction of the hormone prostaglandin which is responsible for death of the CL. Thus, oxytocin injections allowed progesterone to continue to be pro-duced by the CL and the mare stayed out of heat.

“Instead of having to give the mare injectable or oral progesterone as a supplement, we tricked the mare into producing her own progesterone lon-ger in the cycle, but at this point we still need further studies to determine if the number of injections can be decreased perhaps by giving a longer acting oxy-tocin,” Squires said.

--Shaila Sigsgaard

Reprod

uctive H

ealth

The study found that administration of oxytocin regulates an enzyme called cyclooxygenase 2,

preventing the production of the hormone prostaglandin which is responsible for death

of the corpus luteum.

“Instead of having to give the mare inject-able or oral progesterone as a supplement, we

tricked the mare into producing her ownprogesterone longer in the cycle,”

-Dr. Ed Squires


Gluck Equine Research Foundation Releases Fifth Research Report

The long-standing and successful partnership between Lloyd’s of

London and the University of Ken-tucky College of Agriculture, Food and Environment continued when representatives from Lloyd’s recently presented a check for $45,000 to UK.

The contribution supports the Lloyd’s Equine Disease Quarterly, a research-based publication dedicated to equine health produced by the UK Department of Veterinary Science.

The award-winning publication in-cludes articles written by prominent researchers from around the world and provides timely and authoritative re-ports on some of the most important issues facing the equine industry. The Quarterly reaches more than 18,000 readers in 102 countries. Available in paper and online, its articles are regu-larly reprinted in numerous scientific and lay equine publications worldwide.

“Last year, Lloyd’s cumulative sup-port surpassed the $1 million mark. That speaks significantly of the market’s long-standing commitment for sup-porting equine research and health,” said Julian Lloyd, bloodstock under-writer with Amlin and chair of Lloyd’s

Livestock Committee. “This year’s con-tribution of $45,000 continues that ef-fort, and we are proud to support the global distribution of Equine Disease Quarterly.”

Mats Troedsson, chair of the Depart-ment of Veterinary Science and direc-tor of the Maxwell H. Gluck Equine Research Center, agreed.

“The Equine Disease Quarterly is a valuable and popular source of infor-mation to equine veterinarians and in-dustry leaders around the world, and the contributions from Lloyd’s cannot be overemphasized,” he said. “We are very thankful and proud of the long-

standing support that has made the success of the Quarterly possible, and we are looking forward to future years of collaborations with Lloyd’s.”

Lloyd’s Equine Disease Quarterly is available to subscribers at no charge. It is co-edited by Roberta Dwyer, Pe-ter Timoney, and Neil Williams from the Department of Veterinary Sci-ence.

The current version of the Equine Disease Quarterly is located online at http://www2.ca.uky.edu/gluck/q_oct13.asp. For more information

about the Department of Veterinary Science and the Maxwell H. Gluck Equine Research Center visit http://www2.ca.uky.edu/gluck/.

Lloyd’s of London is a 325-year-old insurance market whose members un-derwrite risk on a direct and reinsur-ance basis in more than 200 countries. As a global leader in specialty insur-ance, Lloyd’s remains committed to supporting equine research and provid-ing the insurance coverage essential to the well-being and prosperity of blood-stock interests worldwide.

--Aimee Nielson

Lloyd’s of London Continues Partnership with UK

Gluck Equine Research Center Director Dr. Mats Troedsson (center, left) received a check from Lloyd’s

Regional Director Patrick Talley (center, right).

The University of Kentucky Gluck Equine Research Foun-

dation published its 2013 Research Report in late March of this year. The Re-search Report 2013 focuses on the UK Maxwell H. Gluck Equine Research Center facul-ty’s research accomplishments and scientific publications dur-ing the 2013 calendar year.

The Research Report is divided into the seven sections (genetics and genomics, immunology, infec-tious diseases, musculoskeletal sci-ence, parasitology, pharmacology/toxicology, and reproductive health) and includes faculty members’ educa-tional backgrounds, interests, research

projects, and graduate students. It also lists research technicians/assistants and visiting scientists in 2013.

The Research Report covers Gluck

Equine Research Center awards and grants, scientific publica-

tions, including books/chapters in books, refer-

eed journal articles, non-refereed journal articles,

and seminars and abstracts/papers presented. The report

also recognizes individuals and organizations that donated

money to the Gluck Foundation in 2013.The Research Report is available

online at www.ca.uky.edu/gluck or at www.ca.uky.edu/equine. For

more information contact Jenny Evans at [email protected] or 859-218-1089.

--Jenny Evans


Annual Seminar Series Kicked Off in January

The schedule for the 2014 University of Kentucky Department of Vet-

erinary Science Diagnostic and Research Seminar Series at the UK Veterinary Di-agnostic Laboratory kicked off Thursday, Jan. 30. The next seminar will be on equine welfare on June 19.

All seminars, except the showcase, short course and October symposium, are free.

The seminar series is co-sponsored by Boehringer-Ingelheim, Kentucky Associa-

tion of Equine Practitioners (KAEP), TheHorse.com and UK Ag Equine Programs. The series is hosted by the UK Gluck Center and UKVDL.

For those who cannot attend in person, TheHorse.com films and ar-chives these lectures, which are free to registered users as Horse Health videos through sponsor Boehringer-Ingelheim.

--Jenny Evans

Several Continuing Education Events Held During the Winter

The University of Kentucky Ag Equine Programs, which includes

the Gluck Equine Research Center and Veterinary Diagnostic Laborato-ry, hosted three continuing education events in two months.

Role of Genetics in Studying Equine Disease

Dec. 17 at Embassy Suites Hosted by the Gluck Center, the Role

of Genetics in Studying Equine Dis-eases Symposium offered an in-depth look at the latest information in this rapidly involving field. Special consid-eration were given to select features of Equine Viral Arteritis (EVA) including host-related factors that may influence establishment of the carrier state in this infection.

The symposium was free and funded by a USDA-NIFA-AFRI grant titled “Identification of genetic factors re-sponsible for establishment of equine arteritis virus carrier state in stallions.”

Another similar seminar will be held in late November.

UK Equine Showcase Feb. 7 at Four Points by Sheraton

The UK Equine Showcase, now in its third year, highlighted the university’s current equine programs and relevant industry findings.

Topics included: Equine Cushing’s disease in the aged horse; Is your horse fat? There’s an app for that!; The Ken-tucky Horse Racing Necropsy Program: for the health and welfare of horses, humans and the racing industry; The economic impact of Kentucky’s equine industry; Stem cells for equine tissue regeneration; Age-related susceptibility of foals to Rhodococcus equi; Genetics, health and performance; and Why did my performance horse test positive for prohibited substances?

5th annual Kentucky Breeders’ Short Course

Feb. 8 at Four Points by Sheraton The 5th Annual Kentucky Breeders’

Short Course was an in-depth program on equine reproduction and horse management issues.

Topics included: Reproductive anato-my and physiology of the mare; Starting and stopping a mare’s cycle; Methods for evaluating stallion sperm; Methods to predict foaling; Diagnosing crytor-chids and ovarian tumors; Problems in newborn foals; Managing your stallion for a natural mating or artificial insemi-nation program; Diagnosing placentitis (placental problems); and a problem mare panel.

New this year, an in-depth reproduc-tive “wet lab” was offered on Feb. 9 to a limited number of participants who wanted a hands-on educational oppor-tunity led by some of the equine indus-try’s foremost experts.

All programs are open to veterinar-ians, owners and managers of all horse breeds or anyone with an interest in learning more about equine reproduc-tion and topics concerning horse man-agement.

To receive emails about upcoming educational seminars, contact Jenny Evans at [email protected].

University of KentuckyGluck Equine Research Center

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Please return this form with your gift to:Gluck Equine Research Foundation, 108 Gluck Equine Research Center, Lexington, Kentucky 40546-0099

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The Gluck Equine Research Center encompasses faculty members that conduct equine research full time in the areas of infectious diseases and immunology, genetics and genomics, musculoskeletal science, parasitology, pharmacology/toxicology and reproductive health. Gifts to the Gluck Equine Research Center are used to support research, build facilities, purchase equipment, provide scholarships for graduate students, create educational material and provide continuing education programs for Veteri-narians and Horsemen.

108 Gluck Equine Research Center Lexington, KY 40546-0099

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