Selenium Deficiency Cases Appearing in Washington

Article Outline

• Causes of Colic in Horses
• Rare Treatment for Equine Cancer a Success
• Unwanted Horse Coalition Meets in Lexington, KY
• IDEXX Laboratories is Now an AAEP Educational Partner
• Johanns Releases NAIS Implementation Plan
  • Standards for Database Integration
• Timoney Elected to NIAA Board; Beeman Retires
• New Director of NADC Named
• AAEP Task Force Issues Guidelines for Equine Infectious Disease Outbreaks

Two horses with severe clinical signs related to selenium deficiency have been seen at the WSU Veterinary Teaching Hospital this year.

“That might not sound like a lot, but both horses died of the condition,” said Dr. Macarena Sanz, a WSU resident veterinarian in equine medicine. “And there may be more cases out in the field that we have not heard about.”

Many horses have mild or subclinical cases of selenium deficiency, with signs such as decreased immune function or impaired reproductive efficiency. Horses with acute cases, however, experience severe muscle abnormalities, and the prognosis for survival is often poor.

“It is important that owners realize selenium deficiency can be prevented,” Dr. Sanz said. “We know most soils in the Northwest, as well as in many other areas in the United States, are deficient in selenium, but owners can supplement their horses' feed to compensate.”

Selenium is a mineral found in soil that horses utilize as a component of an enzyme that helps protect cell membranes from the damage caused by normal cell metabolism. Selenium works in conjunction with vitamin E. If selenium is not present, the cells may fragment and die. Selenium also helps the immune system function, so selenium deficiency is associated with immune suppression, and horses may have a decreased resistance to infections.

Horses usually get the selenium they need while foraging. However, plants grown in selenium-deficient soils will be low in this mineral, and horses can develop a deficiency. Both foals and adult horses are susceptible to what is called nutritional muscular dystrophy (also known as white muscle disease, muscular dystrophy, or nutritional myodegeneration). This is a degenerative condition in which muscles actually break down. This disease is also present in other species such as pigs, calves, and lambs.

“What we see is massive muscle damage,” Dr. Sanz said. “The clinical signs and the severity of the disease vary depending on the muscles affected. When the heart is affected, the prognosis is very poor. Affected foals can be weak at birth or they may look normal the first 24 hours of life and be weak and recumbent or unable to nurse later on.”

Signs of selenium deficiency or nutritional muscular dystrophy in horses include severe muscle cramps, sweating, stiffness, and an increased pulse. An affected horse may also have red or brownish urine, indicating muscle damage. Skeletal muscles, heart, and the chewing muscles are more commonly affected in adult horses, and the muscles involved in nursing are more commonly involved in foals.

“A severely affected horse will have painful muscles and be stiff, won't want to walk, and is sore when touched,” Dr. Sanz said. “Other times in adult horses, they will appear healthy, but won't be able to swallow or chew.”

A diagnosis is made based on clinical signs and a blood test to determine the amount of selenium present. A test also can measure concentrations of an enzyme of which selenium is a component. This test is particularly useful in cases in which the horse has recently been treated with a selenium product.

“Once a horse has selenium deficiency, we supplement selenium and vitamin E and provide supportive treatment until muscle regeneration occurs,” Dr. Sanz said. “Sometimes horses are affected severely and there is nothing we can do for them.”

“Selenium deficiency in horses can be prevented, so the main message is to supplement their feed if you are in a deficient area,” she said. “We don't know why some horses are affected with severe clinical signs and some are not, but the risk is certainly there.”

Supplementation should be performed under veterinary supervision. An appropriate supplementation rate is approximately 1 to 3 mg selenium daily per horse. Horse owners should be careful to supplement their horses in the proper amounts. Too much selenium can lead to toxicity, which can cause hair loss from the mane and tail, hoof problems, and lameness.

Numerous products are available for selenium supplementation, including oral and injectable products. Some, but not all, salt blocks contain selenium. If this is the only source of selenium in the diet, many horses do not ingest enough of the block to attain optimal selenium levels. It is best to consult a veterinarian about the most appropriate supplementation program for individual horses in a given area.

For more information about selenium deficiency in horses or how to prevent it, contact the WSU Veterinary Teaching Hospital at 509-335-0711.

Reprinted from: Equine News, Fall 2006, Vol. 3, Number 4, Washington State University College of Veterinary Medicine

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Causes of Colic in Horses 

Colic is a common ailment in horses that can have more than 70 causes. According to data from the USDA, colic is the second leading cause of death in horses, next to old age.

These data, generated from a 1998 study conducted by USDA's National Animal Health Monitoring System, and including information from the National Agricultural Statistics Service and the American Horse Council, estimated that 4% of horses suffer from colic each year, and of those, 11% die of it. The annual cost to horse owners was estimated at $115 million.

“Colic is a general term for abdominal pain or a belly ache in a horse that can be related to the gastrointestinal tract or other organs, such as the liver or kidney,” said Dr. Julie Cary, a WSU clinical instructor of equine surgery and emergency care. Some cases of colic are mild, but others can be fatal depending on the cause.

Colic can be caused by gas distension, food impactions, intestinal tract spasms, intestinal displacement or torsion (twist), intestinal enteritis or inflammation, and gastric distension or stomach rupture. Some are more specific to different geographic areas, such as sand or enterolith formation. At other times, the colic's cause is unknown.

“The most common cause is gas colic or spasmodic colic,” Dr. Cary said. “With gas colic, the horse gets a big, uncomfortable gas bubble in its intestine, and with spasmodic colic, part of the intestine spasms, which causes pain.”

These types of cases are generally mild compared with other forms of colic, including intestinal displacements, twists in the large colon, or strangulation of a section of the bowel (generally in the small intestine), resulting in a loss of blood supply. Examples of strangulation include an abdominal lipoma or fatty tumor that wraps around a section of small intestine, or when the small intestine works its way into a small space, such as the epiploic foramen.

Colicky horses often display symptoms such as pawing at the ground, looking to their side, rolling or laying down and getting up, and a loss of appetite or refusal to eat. Unfortunately, determining how serious a case of colic is based on the horse's symptoms can be difficult.

“Some cases resolve when the horse is walked around, which can relieve a gas bubble that builds up,” Dr. Cary said. “But if the horse does not show improvement within 20 minutes, then it is best to have a veterinarian evaluate it.”

Some horses may also appear violently painful, which may indicate a serious case. In this instance, contact a veterinarian immediately.

To help with gastrointestinal pain, many veterinarians administer a nonsteroidal antiinflammatory drug, as well as giving mineral oil through a naso-gastric tube. Sedation and other more potent pain medications may be needed, depending on the horse's specific condition.

“As veterinarians, we often pass a nasogastric tube through the horse's nasal passage and down through its throat to its stomach,” Dr. Cary said. “Horses cannot vomit, so the tube is important because if the horse is building up pressure in its stomach, the excess pressure and stomach contents may rupture it. Decompressing the stomach with a tube can be life-saving.

If spasmodic colic is determined as the cause, veterinarians can administer a drug called Buscopan that will treat the spasms. “This drug is very specific in its treatment of this certain type of colic and will actually stop the spasms,” Dr. Cary Said.

“If the case is more serious, often the horse's heart rate will be high, and it will not respond to drugs,” she said. “It may also have reflux in the gastric tube, or will not have a normal rectal examination. A lot of things can cause a serious case, so it is best to get a veterinarian involved.”

Some horses with a serious case of colic may need surgery. “At the WSU Veterinary Teaching Hospital, we see about 75 to 90 colic cases a year, and of those, about one third to one half need surgery,” Dr. Cary said. “Usually, approximately 90% of colic cases respond to routine treatments and do not require hospitalization or surgery, but we commonly have serious cases referred to us here at WSU.”

“The survival rate of horses that do need surgery depends on what the cause of colic is,” she explained. “If the horse is seen early, no matter what the cause, we have a very good chance of saving it and it often has a faster recovery.”

Horses that do not require surgical intervention may receive intensive fluid therapy or other more specific medication and advanced care.

Colic can happen in any horse; however, owners can take steps to try to prevent it. First, keep a routine feeding schedule, and make sure horses always have access to clean water, especially during weather changes. Owners should throw out moldy hay or grain, and feed hay and water before grain. Exercise is also important for horses, but it is best to wait until they have cooled down before being fed or watered. Intestinal parasites also may cause colic, so it is best to keep horses on a regular preventive worming schedule.

“Any food and exercise changes an owner plans for a horse should also be made gradually,” Dr. Cary said.

For more information about colic or in case of a colic emergency, contact the WSU Veterinary Teaching Hospital at 509-335-0711. More information about colic can also be found at www.myhorsematters.com.

Reprinted from: Equine News, Fall 2006, Vol. 3, Number 4, Washington State University College of Veterinary Medicine

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Rare Treatment for Equine Cancer a Success 

Squamous cell carcinomas are one of the most commonly diagnosed cancers in horses. Last year, the equine surgical team at WSU's College of Veterinary Medicine successfully treated this type of tumor near a horse's eye with a method typically reserved for smaller animals, such as dogs, cats, and people.

Ghostbuster, a teenaged Clydesdale/Thoroughbred cross, suffered persistent weeping in his right eye due to a squamous cell tumor, a slow-growing type of tumor that can become malignant over time.

“His owners and referring veterinarian, Dr. Andy Denome, had tried a variety of unsuccessful treatments, including topical chemotherapeutic agents, but it continued to come back every time the treatment ended,” said Dr. Kelly Farnsworth, a professor and equine surgeon at WSU.

Clinical evidence has shown that squamous cell carcinomas are susceptible to radiation therapy. The WSU Veterinary Teaching Hospital features a linear accelerator similar to that used with human cancer patients, one that can deliver very focused radiation therapy. One of the most advanced machines in the world dedicated to animal cancer treatment, the WSU linear accelerator uses either electron beams or high-energy x-ray radiation to treat tumors with minimal impact to the surrounding healthly tissue.

“The linear accelerator works extremely well in similar tumors in dogs and cats, so we thought why not try it in this case?” Dr. Farnsworth said.

Two challenges faced Ghostbuster and his WSU veterinarians—his size and the number of treatments he was to receive. At 1,400 pounds, Ghostbuster would be the largest animal to be treated in WSU's linear accelerator. WSU College of Veterinary Medicine cancer specialist Dr. Janean Fidel developed the protocol to be used, and the WSU equine team developed a method of anesthetizing the horse, and moving him to and from the linear accelerator in a safe and rapid manner.

“We used a protocol where we anesthetized Ghostbuster twice a day for 5 days,” Dr. Farnsworth said. “This protocol had not been used in horses before. Typically the procedure from the time he was anesthetized to the time he was back in the recovery stall was around 12 to 13 minutes. The treatment in the linear accelerator lasted only about 25 to 30 seconds, and the rest of the time was transporting him to and from the linear accelerator. He came through the treatments without any problems at all.”

Better yet, Ghostbuster's tumor completely regressed and more than a year later, the horse is cancer free. The incessant weeping in his eye was also eliminated. “The results of this therapy in other species and certainly in this horse have been very encouraging,” Dr. Farnsworth said.

Radiation therapy is not the only option in treating a horse with squamous cell carcinoma, but the treatment depends on the extent that the tumor has spread and the stage of cancer the horse has.

“If we find the tumor only on the third eyelid, which is the most common place we see it, then we generally just surgically remove the third eyelid,” Dr. Farnsworth said. “If the tumor is small and hasn't spread, the horse can be treated with laser radiation to evaporate the tumor and make it go away. But when the cancer is extensive and involves deeper structures, the options are removing the eye or trying some other form of radiation.

“Many horses end up losing the eye to prevent tumor regrowth,” Dr. Farnsworth said. “This was not necessary with our protocol, so I think there are a lot of horses that could benefit from this treatment.

Reprinted from: Equine News, Fall 2006, Vol. 3, Number 4, Washington State University College of Veterinary Medicine

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Unwanted Horse Coalition Meets in Lexington, KY 

On October 31, 2006, the Unwanted Horse Coalition met officially for the first time under the auspices of the American Horse Council at the United States Equestrian Federation headquarters in Lexington, Kentucky.

The meeting was attended by representatives from the American Association of Equine Practitioners, American Paint Horse Association, American Quarter Horse Association, American Veterinary Medical Association, The Jockey Club, National HBPA, National Thoroughbred Racing Association, Professional Rodeo Stock Contractors, Thoroughbred Owners and Breeders Association, United States Equestrian Federation, and US Trotting Association.

Meeting participants discussed a number of issues relating to the unwanted horse situation in the United States, and committees were established to continue work on Communications and Education, Research, Fundraising, and Steering functions of the UHC. The Communications and Education Committee will work to develop a website, informational brochures, a guide to responsible horse ownership, and continue to develop public outreach strategies, while the appointed Research Committee will focus on compiling up-to-date information on issues such as horsemanship, alternative careers, retirement, retraining, and euthanasia/disposal options. The Funding Committee will continue to recruit new UHC Members, in addition to individual donors and exploring corporate sponsorships, and the Steering Committee will oversee the overall direction of the Unwanted Horse Coalition.

“This meeting was an important step in establishing the core goals of the Unwanted Horse Coalition,” said Dr. Tom Lenz, Chairman. “There is alot of work to be done, but I am confident that we have established achievable short- and long-term objectives and are prepared to continue moving forward with the mission of the Coalition.”

As the national trade association representing the horse industry in Washington, D.C., the American Horse Council works daily to represent equine interests and investments. Organized in 1969, the AHC promotes and protects the industry by communicating with Congress, federal agencies, the media, and the industry on behalf of all horse-related interests every day.

The AHC is member supported by individuals and organizations representing virtually every facet of the horse world from owners, breeders, veterinarians, farriers, breed registries, and horsemen's associations to horse shows, race tracks, rodeos, commercial suppliers, and state horse councils.

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IDEXX Laboratories is Now an AAEP Educational Partner 

IDEXX is proud to announce that it is now an Educational Partner of the American Association of Equine Practitioners (AAEP). This new relationship will create additional educational choices for AAEP member veterinarians, veterinary students, and horse owners.

IDEXX has long been focused on equine care and the practitioners who provide it—with everything from diagnostics and consulting to treatment and follow-up monitoring. IDEXX products and services include in-hospital diagnostic treatments, rapid assay tests, imaging technology, telemedicine, pharmaceuticals, reference laboratories, and practice management software.

IDEXX has supported the AAEP through veterinary education, and this unique opportunity will allow us to add to that curriculum, effectively targeting the goals and needs of AAEP members.

Reprinted from: IDEXX Equine Edge Newsletter – Fall 2006 http://www.idexx.com/equine/equineedge/2006fall.jsp

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Johanns Releases NAIS Implementation Plan 

Agriculture Secretary Mike Johanns has announced the release of an implementation plan that outlines timelines and benchmarks for the establishment of the National Animal Identification System (NAIS), along with a plan for the initial integration of private and state animal tracking databases with NAIS.

“Developing an effective animal identification system has been a high priority for USDA and we've made significant strides toward achieving a comprehensive U.S. system,” said Johanns. “We recognize that this represents one of the largest systematic changes ever faced by the livestock industry.”

The implementation plan continues to set an aggressive timeline for ensuring full implementation of the NAIS by 2009. It establishes benchmarks for incrementally accomplishing the remaining implementation goals to enable all components of the NAIS to be operational by 2007, and to achieve full producer participation by 2009.

Several important components have already been accomplished. These include the development of premises registration systems in each state and the issuance of guidelines for the manufacture and distribution of animal identification numbers. More than 270,000 premises are currently registered.

“We have a plan in place and we need producers to take the first step by registering for a premises identification number,” said Jim Niewold, a pork producer from Loda, IL, and member of the Swine ID Implementation Task Force.

“The program was developed by producers to protect animal health. Voluntary implementation of the program by our industry will help us transition smoothly…” Niewold said.

Standards for Database Integration 

USDA also released the general technical standards for animal tracking databases that will enable integration of private systems with the NAIS. Private database owners are invited to submit applications for system evaluation to USDA and offer feedback as the final technical requirements are established. USDA will then enter into cooperative agreements with owners of databases that meet the standards. The application for system evaluation and a draft cooperative agreement are available on the NAIS website at: www.usda.gov/nais.

By early 2007, USDA expects to have the technology in place, called the Animal Trace Processing System or commonly known as the portal system. The animal tracking databases will record and store animal movement tracking information for livestock that state health officials will query only for animals of interest in a disease investigation.

USDA's Animal and Plant Health Inspection Service (APHIS) is also finalizing $3 million in funds that will be awarded to a number of states and tribes to conduct field trials to analyze information pertaining to animal identification. Field trials will focus on the valuation of new technologies for animal identification and automated data collection. APHIS will also fund an economic study focusing on the cost of NAIS implementation within a state, the development of procedures to measure the performance of identification devices, and a bistate study to develop recommendations regarding livestock exhibitions to achieve compatibility with the NAIS.

The NAIS implementation plan, along with more information about the program, is available at www.usda.gov/nais.

Reprinted from Equine Health Report published by the National Institute for Animal Agriculture in cooperation with USDA/APHIS, Spring/Summer 2006, http://www.animalagriculture.org/equine/equineintropage.asp

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Timoney Elected to NIAA Board; Beeman Retires 

Dr. Peter Timoney, an internationally renowned expert in equine infectious diseases, was elected to the board of directors of the National Institute for Animal Agriculture at the organization's annual meeting in Louisville in April.

Timoney is chair of the University of Kentucky Department of Veterinary Science and director of U.K.'s Maxwell H. Gluck Equine Research Center, considered by many as the preeminent equine research center in the world. Known for his work on the pathogenesis and epidemiology of equine infectious diseases, Timoney is an internationally recognized authority on equine viral arteritis.

Timoney received his PhD from the University of Dublin and is a graduate of the Royal College of Veterinary Surgeons.

Timoney was elected to a 3-year term. He served as chairman of the NIAA Equine Health Committee from 2004 until his election to the board.

Recognized in April at the annual recognition banquet for his service to the organization was Dr. Marvin Beeman, an equine practitioner from Littleton, CO, who stepped down from the NIAA board of directors after completing a 3-year term. Beeman has provided NIAA with leadership in the area of equine health issues for a number of years and was the first chairman of the organization's Equine Health committee, established in 2002.

In addition to his service to NIAA, Beeman is a past president of the American Association of Equine Practitioners, a former member of the Secretary's Advisory Committee on Foreign Animal and Poultry Diseases, and serves on the American Horse Council board of trustees.

Reprinted from Equine Health Report published by the National Institute for Animal Agriculture in cooperation with USDA/APHIS, Spring/Summer 2006, http://www.animalagriculture.org/equine/equineintropage.asp

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New Director of NADC Named 

Animal reproductive physiologist Kurt A. Zuelke is the new director of the U.S. Department of Agriculture's National Animal Disease Center (NADC) in Ames, Iowa, effective May 28, 2006.

ARS Administrator Edward B. Knipling said Zuelke, who for the past 5 years has served as research leader at the agency's Biotechnology and Germplasm Laboratory in Beltsville, MD, was officially appointed in April after a year long international recruitment process.

Before serving with ARS, Zuelke was with the Victorian Institute of Animal Science in Attwood, Australia.

Reprinted from Equine Health Report published by the National Institute for Animal Agriculture in cooperation with USDA/APHIS, Spring/Summer 2006, http://www.animalagriculture.org/equine/equineintropage.asp

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AAEP Task Force Issues Guidelines for Equine Infectious Disease Outbreaks 

The Infectious Disease Task Force of the American Association of Equine Practitioners (AAEP) has developed guidelines for the control of contagious infectious disease within the horse population. Recommendations are provided for the control of suspected cases of infectious respiratory, neurologic, diarrheal, and vesicular disease. The symptom-based guidelines provide a detailed action plan for veterinarians as they address a possible infectious disease outbreak. From the point at which a case of infectious disease is suspected, the guidelines offer measures to control the spread of infection, diagnostic testing options, and communication considerations.

Highlights of “Equine Infectious Disease Outbreak: AAEP Control Guidelines” include:

The Task Force stresses that the veterinarian on scene is the most qualified person to initiate the outbreak control plan, and is critical to effective outbreak management. Each infectious disease outbreak is unique and an existing plan may require modification for specific situations.

“When a large group of horses gathers, be it at a racetrack or a horse show, all those involved in the horses' care should be vigilant about monitoring the health of the animals. It is key that the presence of contagious disease be quickly identified and responsibly addressed,” said Mary C. Scollay, DVM, chair of the AAEP Infectious Disease Task Force. “Our expectation is that the AAEP guidelines will assist veterinarians and equine caretakers in minimizing the impact of infectious disease in a given horse population.”

The Task Force, chaired by Dr. Scollay, comprised leading researchers, internal medicine specialists, and private practitioners: William Bernard, DVM, DACVIM; Brian S. Carroll, DVM; Roberta M. Dwyer, DVM, MS, DACVPM; Robert E. Holland, Jr., DVM, Ph.D.; Daniel G. Kenney, VMD, DACVIM; Maureen T. Long, DVM, Ph.D.; Paul Lunn, BVSc, MS, Ph.D., MRCVS; and Josie L. Traub-Dargatz, DVM, MS, DACVIM.

The guidelines are available to veterinarians and can be accessed only through the members-only area of the AAEP Web site, http://www.aaep.org/. For questions about the guidelines or how to gain access, contact Sally J. Baker, AAEP director of marketing and public relations, at sbaker@aaep.org or (859) 233-0147.

The American Association of Equine Practitioners, headquartered in Lexington, Kentucky, was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse. Currently, the AAEP reaches more than 5 million horse owners through its 9,000 members worldwide and is actively involved in ethics issues, practice management, research and continuing education in the equine veterinary profession and horse industry.

Reprinted from the AAEP Press Room web page: http://www.aaep.org/press_room.php?id=248

Contact: Sally J. Baker, APR, Director of Public Relations 859-233-0147, sbaker@aaep.org.