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NEWS & INFORMATION


 

 


Equine Vaccination Guidelines released by AAEP 1-24-08

January 24, 2008—The Infectious Disease Committee of the American Association of Equine Practitioners has issued revised guidelines for the administration of vaccinations to horses. The Committee, chaired by Mary Scollay, DVM, has made recommendations for the use of vaccines based on the age of the horse and its previous vaccination history. The guidelines are intended to serve as a reference for veterinarians as they employ vaccines in their respective practices.

Highlights of “Guidelines for the Vaccination of Horses” include:

The identification of tetanus, Eastern/Western Equine Encephalomyelitis, West Nile virus and rabies as “core” vaccines. Core vaccines have clearly demonstrated efficacy and safety, and exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.

The addition of a vaccination protocol for anthrax.

Recommendations for the storage and handling of vaccines, as well as information on vaccine labeling and adverse reactions.

Inclusion of the AAEP’s Infectious Disease Control Guidelines, which provide an action plan for the containment of infectious disease during an outbreak.

The Committee stresses that veterinarians, through an appropriate veterinarian-client-patient relationship, should use the vaccination guidelines coupled with available products to determine the best professional care for their patients. Horse owners should consult with a licensed veterinarian before initiating a vaccination program.

“The goal of the guidelines is to provide current information that will enable veterinarians and clients to make thoughtful and educated decisions on vaccinating horses in their care,” explained Dr. Scollay. “The vaccination schedules are complemented by supporting information on topics including vaccine technology and disease risk-assessment, allowing veterinarians to customize vaccination programs specific to the needs of an individual horse or group of horses. The impact of infectious disease has been felt across the equine industry in recent years, and the Committee hopes that these guidelines will be a useful tool in preventing or mitigating the effects of equine infectious disease.”

The Committee, comprised of researchers, vaccine manufacturers and private practitioners, updated guidelines that were established by the AAEP in 2001.

The complete document, along with easy reference charts, is available on the AAEP Web site at http://www.aaep.org/vaccination_guidelines.htm.

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.

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Colic: Updates & Prevention (From: AAEP News, Dr Nancy Loving)

 

Colic is one of those emergency crises that horse owners seek to avoid. The National Animal Health Monitoring System (NAHMS) survey says that for every 100 horses, there will be 4.2 colic events every year. 1.2 percent of these events will be surgical, and 11 percent will be fatal. The objective of a conscientious horse owner is to find ways to prevent colic so your horse doesn’t become one of these statistics, while also understanding how to appropriately manage colic if it does occur.

 

Colic & Vital Signs

 

A colicky horse might appear depressed or “zoned-out,” or he may display anxious behavior like pawing, looking at his sides, lying down, getting up, rolling, and a general state of distress. A thorough veterinary examination helps determine the cause of these behaviors, and also rules out other medical conditions like tying-up, laminitis, pneumonia or foaling difficulties. When you call your veterinarian to attend your horse, it is greatly helpful to have information about your sick horse’s vital signs so a determination can be made about the seriousness of the horse’s condition, and how quickly the horse needs medical attention.

Learn how to take your horse’s vital signs -- heart rate, temperature, capillary refill time, and whether or not there are audible gut sounds. Normal heart rate is about 32 to 40 beats per minute (bpm). A heart rate over 64 bpm signifies pain and possibly a more serious problem. A stethoscope is the easiest means of obtaining a horse’s heart rate, but if you don’t have one, you can take a pulse from the big vessels behind the fetlock or along the jaw. The digital pulses on a limb are often difficult to feel on a healthy horse that isn’t experiencing any problems, so practice in advance.

Normal rectal temperature in an adult horse is 97 to 101 degrees Fahrenheit, while a foal may normally run up to 102 degrees Fahrenheit. A horse may feel sick, depressed and off his feed for many reasons, including a fever, but a fever may also be a sign of some serious intestinal problem related to colic, like a necrotic, leaking or ruptured bowel.

The gums should be healthy and pink and should return to that color within two seconds of pressing with your finger on the gum line above the teeth and then releasing. This is referred to as capillary refill time. A longer time to return color to the gums indicates that the circulatory system is in distress. Gums that are pale with a purple flush around the edges of the teeth, called injection or margination, denotes endotoxin in the circulation as a result of bacterial overgrowth from gut stagnation.
 

What & What Not to Do

 

Historically, horse owners have walked a colicky horse while awaiting arrival of the vet. This as an overrated and old myth; a horse should be kept walking only if he persists in trying to roll or thrash and is a danger to himself or humans. If the horse will lie quietly, you can let him be. When you first discover your horse has colic, it is valuable to try trotting him vigorously on the longe line for about 15 minutes to see if that will ease pain from a gas or spasmodic colic. A trailer ride also jiggles the bowel to achieve similar relief for a simple colic. Under no circumstances should non-steroidal anti-inflammatory medications (NSAIDs), like phenylbutazone or BanamineR, be given without first discussing your case with your veterinarian. These drugs are capable of masking the pain of a surgical condition and thereby may delay appropriate treatment. In addition, a horse with intestinal stasis and poor motility may not absorb oral medications sufficiently to provide a therapeutic advantage when intravenous administration would work better.

 

Veterinary Assessment

 

Once your vet arrives, your horse will be evaluated with a thorough physical exam. Additionally, your vet may conduct a rectal examination to determine if there is an impaction or a displaced bowel. A nasogastric tube passed into the nostril, down the esophagus and into the stomach is helpful to check for reflux and to administer fluids, electrolytes, and laxatives when indicated. Depending on the horse’s condition, it might be appropriate for your horse to receive pain-relieving drugs and intravenous fluids to improve his comfort and to improve gut motility. The administration of ample IV fluids is highly effective in increasing fluid volume in the bowel; over-hydration of the intestinal tract and its circulation improves blood flow and motility that might relieve an impaction or return a mild displacement to normal.

In the event that a horse does not respond well to medical therapy in a reasonable time, the horse should be shipped to a referral hospital for further diagnostic workup and possible surgery. Abdominal ultrasound, abdominal fluid analysis, and blood analysis are helpful to perform on site at a referral hospital to gain as much information as possible about your horse’s condition. In addition, precautionary steps will be taken to protect against laminitis, which is a possible side effect of severe colic due to circulatory disturbances created by the release of endotoxins associated with gut stagnation.

 

Preventive Steps -- Updates

 

There are steps a horse owner can take to minimize the risk of colic.

Many practical measures rely on altering feeding practices, as for example, limiting the amount of grain fed – too much grain is known to disturb intestinal health. A pound or two a day is not necessarily problematic provided a horse also has access to 15 to 20 pounds of hay per day (for the average 1000 lb. horse), but in general, grain or concentrates should not be the first choice in nutritional options. Optimal digestion occurs in the large intestine, but grain is processed mostly in the small intestine yet is incompletely digested there. This results in passage of a lot of starch into the large intestine where it is not digested effectively. Subsequently, the large intestinal pH is altered to a more acid environment, which then causes the die-off of resident bacterial flora that are essential for efficient processing of fiber. Other bacteria also die in the altered environment, with the potential to release endotoxin into the circulation.

Grain also amplifies acid production in the stomach. Gastric ulcers are known to be more prevalent in grain-fed horses, especially when fasted for long periods between feedings. A horse with ulcers might suffer intermittent bouts of colic, be reluctant to work or is lack-luster in performance, and often has a poor appetite in spite of weight loss. Ulcers occur in as many as 93 percent of high-stressed horses (racehorses, high-level show horses) and 60 percent in the average riding horse or less intense show horse. Risk factors for ulcers include stress of any kind, such as transport, illness or injury, dehydration, confinement or social competition in a herd. NSAIDs (phenylbutazone or BanamineR) are notorious in their propensity to induce gastric ulcers. Not all risk factors can be controlled, but offering free-choice hay and substituting other feeds, like soaked beet pulp or high-fat rice bran or vegetable oil, for grains helps to reduce the risk of developing gastric ulcers. Gastric ulcers are confirmed and visualized with a gastroscope, which is a three meter long, fiberoptic tube with an attached camera that allows a view of the inside of the stomach. A horse must first be fasted for about 12 hours prior to passing the tube and scooping his stomach. Anti-ulcer medications are currently available as a safe means of treating a horse with gastric ulcers.

Feeding practices influence digestive efficiency in other ways: Grain ingestion reduces the fluid content of the bowel by 15 percent, and to compound the problem, in an effort for a horse owner to control a horse’s daily caloric intake, a grain-fed horse is typically offered less hay. Yet, fiber is an essential component of intestinal health, and it also serves as a fluid reservoir in the bowel. The common practices of keeping horses in stalls for a large portion of the day and feeding them large meals only twice a day wreak havoc with their digestive health. Stall confinement increases the risk of colic by at least 50 percent. Intestinal motility is reduced by confinement and by fasting between large meals. With reduced intestinal motility comes the risk of impaction colic or gas distention. The best strategy for minimizing colic is to offer free-choice grass hay so a horse can “graze” intermittently through the day. Also, limit grain fed, while providing daily turnout and regular exercise.

Other causes of colic include sand ingestion, often related to restricted access to hay. Ample fiber in the diet is instrumental in moving dirt and sand through the digestive tract. If fiber is restricted and/or if a bored horse nibbles at remaining particles of hay on the ground, sand may accumulate in the bowel. The best prevention for sand colic is to feed ample hay, and, when possible, use feeders (like large tractor tires) to confine the hay and keep it from being strewn across the ground. Since many horses persist in throwing hay out of many forms of commercial feeders, sand ingestion cannot be prevented entirely – it is recommended to feed psyllium for a week each month to help move through any sand that has collected.

Obesity and parasites also are risk factors for colic, but a conscientious owner can prevent and manage these concerns. Your horse should be fed by weight, not volume since the density of hay varies from bale to bale. Pasture your horses on non-irrigated, dryland pasture when possible. If your only pasture option is a rich, irrigated field, then many problems, including obesity, can be avoided by fitting your horse with a grazing muzzle or by limiting turnout time. This prevents intake of highly fermentable, rich grass that can contribute to gas or spasmodic colic episodes.

Tapeworms have been identified to cause as many as 22 percent of spasmodic colic cases. Parasite control is managed with regular deworming schedules of the appropriate anthelmintics. It also is important to clean up manure at least twice a week to limit the development of other infective parasite larvae in areas where the horse might eat. It also helps to rotate your pastures to prevent overgrazing and to facilitate ultraviolet kill of remaining infective larvae.
 

In Summary

 

The ideal management that prevents colic includes the following recommendations:

Feed at least 60 percent of the daily ration as forage (hay or pasture)
When possible, pasture in non-irrigated fields and/or use a grazing muzzle to control weight and intake of rich forage
Limit grain to as little as possible – none is preferable
Substitute high-fat feeds and high-fiber feed for grain supplements when more calories are needed
Provide feeding systems that limit the intake of sand and dirt
Provide plenty of turnout and exercise each day
Provide clean, ice-free drinking water
Implement regular and frequent deworming programs for the herd
Implement a herd health program of preventive care
Minimize stress (transport, herd dynamics, housing, illness, injury) as much as possible

Not every one of these suggestions is feasible for every horse owner, but many practical steps can be taken to improve digestive health. Even the smallest details can make a large difference. In the overall picture, a healthy horse is a happy horse and able to perform to his best ability.

For more in-depth information, please refer to Dr. Loving’s book, All Horse Systems Go:The Horse Owner’s Full-Color Veterinary Care and Conditioning Resource for Modern Performance, Sport and Pleasure Horses.

 

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Strangles: Dispelling the Myths

, Posted March 27 2007 TheHorse.Com

 
The infection caused by the bacteria Streptococcus equi,, commonly known as strangles, has been described in horses for almost 800 years. The name strangles describes the condition in which an affected horse is suffocated as lymph nodes in the throat region become enlarged and obstruct the airway. Many misunderstandings exist regarding strangles, most likely due to horse people passing on tales regarding the infection.

Strangles is characterized by a sudden onset of fever with formation of abscesses under the jaw and within the throat approximately 7-21 days following exposure. These abscesses can open and produce a thick yellow discharge, which might also be seen as a nasal discharge. The symptoms of the disease can vary from severe lymph node enlargement with difficulty breathing to no outward signs with only a slight nasal discharge.

Misunderstandings regarding the transmission of the bacteria causing strangles, Streptococcus equi, exist. It is often said that once a farm has had an outbreak of strangles, the problem will always be on the farm and can show up at anytime. A fact that needs to be understood is that the source of infection from year to year and farm to farm is the horse, not any part of a barn, pasture, farm, or other animals besides horses.

With two to three weeks after outward clinical signs of strangles have ceased, the majority of horses clear the bacteria and no longer pose a threat for infecting others.

However, following an outbreak a number of horses (can be as high as 10%) cannot clear the bacteria and become persistently infected. The bacteria can survive in the guttural pouches, which are located in the pharyngeal region, for years. A carrier horse that undergoes some form of stress such as foaling, weaning, competing at a show, or a simple change in routine, can begin to shed the bacteria and serve as a source of infection for future outbreaks.

Transmission of Strep. equi occurs by either direct or indirect contact. Direct transmission occurs during horse-to-horse contact through everyday social behavior.

The indirect transmission can be more difficult to control and occurs through the sharing of contaminated stalls, water buckets and troughs, feed tubs, and bits. Water sources, either in shared stalls or in field settings with a common water supply, are the most common culprit when it comes to infecting a herd during an outbreak. When a horse is shedding the bacteria and dips their nose into a water source, the water serves as a reservoir for the bacteria to be passed to every horse that comes in contact with the water.

There is a misunderstanding regarding the persistence of Strep. equi in the environment. Besides in a water source, the bacteria will not survive for prolonged periods in the environment. This means horses do not become infected with the bacteria from the soil, grass, or fences unless a horse currently shedding bacteria is present.

Strangles is often diagnosed by clinical signs, but it takes a positive culture with or without a positive PCR test to confirm the presence of Strep. equi. Both tests utilize a sample from a nasal wash or guttural pouch sample or direct swab from an enlarged lymph node. Each test has its limitations, but when used in conjunction can be very effective in detecting the bacteria in a horse showing clinical signs and a carrier horse that might appear healthy.

Once a horse is confirmed to have strangles, they should be isolated from other horses and provided with supportive care to control fevers and ensure an open airway. The best management during an outbreak is to segregate the horses showing clinical signs, and monitoring the temperatures of the healthy horses for two to three weeks after the last horse with clinical signs was removed. Once the affected group of horses is no longer showing signs, they should be tested to confirm they have not become carriers of the bacteria. This is a critical step in preventing future outbreaks.

Steps can be taken to prevent the exposure of your horse to strangles. It is important to remember that a horse does not have to be showing active clinical signs of strangles to be capable of infecting others. Care should be taken to minimize exposure to other horses, particularly at shows and farms with a changing population. When traveling to shows, water buckets should be brought and not shared with other horses. Do not permit direct or indirect contact with other horses while at the show. This includes nose-to-nose contact as well as sharing such things as stalls, water buckets, feed tubs, grooming tools, tack, and trailers.

In a stable or herd situation, a few simple prevention methods can be used to decrease the likelihood of exposure to strangles. Isolation of all horses for two to three weeks before they come in contact with others can decrease the potential exposure. Testing incoming horses for Strep. equi can be an effective tool in limiting the introduction of strangles into a herd or stable. Strangles is a preventable disease and with the proper steps, the risk of exposure can be minimized.

Ask your veterinarian how they can help you protect your horse and farm from this preventable disease.

Article courtesy of The Kentucky Equine Education Project (KEEP), www.horseswork.com.


UC Davis experts: Sources on West Nile virus, mosquito-borne diseases

UC Davis has the largest West Nile research and public-testing programs in the state of California.

Read new and important information on biology of West Nile, mosquito control, and West Nile in

people and animals.

 

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What is EVA?

Equine viral arteritis (EVA) is an infectious viral disease of horses that causes a variety of clinical symptoms, most significantly abortions. The disease is transmitted through both the respiratory and reproductive systems. Many horses are either asymptomatic or exhibit flu-like symptoms for a short period of time. An abortion in pregnant mares is often the first, and in some cases, the only sign of the disease. EVA has been confirmed in a variety of horse breeds, with the highest infection rate found in adult Standardbreds.


Breeders, racehorse owners, and show horse owners all have strong economic reasons to prevent and control this disease. While it does not kill mature horses, EVA can eliminate an entire breeding season by causing numerous mares to abort. In addition, U.S. horses that test positive for EVA antibodies and horse semen from EVA-infected horses can be barred from entering foreign countries. As the horse industry becomes increasingly internationalized, nearly all major horse-breeding countries are including in their import policies measures to reduce the risk of EVA. The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service's (APHIS) Veterinary Services (VS) program provides the equine industry with EVA diagnostic and surveillance support.

History

In the past 15 years, few equine diseases have stimulated more interest or gained greater international notoriety than EVA The disease was thrust into the limelight of industry attention following a 1984 epidemic on a large number of Thoroughbred breeding farms in Kentucky. No outbreaks of EVA had previously been reported in Thoroughbreds in North America. Few equine diseases have been the subject of more misinformation or misperception than EVA. It is an acute, contagious viral disease known to affect horses and other members of the equid family only. EVA is not transmissible to humans or other domestic species. Like influenza and rhinopneumonitis, it is considered primarily a viral infection of the equine respiratory tract.

 

More than a century ago, a disease fitting the clinical description of what we now call EVA was reported in European veterinary literature. However, the virus was not isolated from horses in this country until 1953 during an epidemic of abortions and respiratory disease.
The most recent EVA epidemic occurred in 1984 when this disease affected 41 thoroughbred breeding farms in Kentucky. This outbreak brought to light two very important findings about EVA: the efficiency with which an acutely infected stallion could venereally transmit the virus and the high carrier rate that immediately occurred in stallions following natural infection with the virus.

Transmission

EVA is primarily a respiratory disease. Particles from acutely infected horses' nasal discharges are inhaled, often during the movement of horses at sales, shows, and racetracks. Horses are herd animals that tend to commingle, and this close contact facilitates the spread of the virus.
However, unlike other respiratory diseases, EVA can also be transmitted venereally during breeding, either naturally or by artificial insemination. When a mare, gelding, or sexually immature colt contracts the disease, the animal will naturally eliminate the virus and develop a strong immunity to reinfection. On the contrary, infected stallions are very likely to become virus carriers for a long time. Once stallions are in the carrier state, they transmit the virus to mares during breeding.
 

While the mare will shed the virus easily, a pregnant mare infected with EVA may pass the virus to her unborn fetus. Depending on the stage of pregnancy, the fetus can become infected, die, and be aborted. If the infected foal is born, it will only live for a few days.

Symptoms

Many horses infected with EVA are asymptomatic. When symptoms do occur in the acute stage of the disease, they can include any or all of the following: fever, nasal discharge, loss of appetite, respiratory distress, skin rash, muscle soreness, conjunctivitis, and depression. Other clinical signs in infected animals are swelling around the eyes and ocular discharge, swollen limbs, swollen genitals in stallions, and swollen mammary glands in mares.
Abortion in pregnant mares is also a symptom of EVA. Abortion rates in EVA-infected mares can be as low as 10 percent or as high as 70 percent.

Diagnosis

Horse owners should suspect EVA when respiratory symptoms accompany an abortion in a mare. Since the clinical signs of EVA are similar to those of other respiratory disease, and no characteristic lesions are in EVA-aborted fetuses, only diagnostic tests can confirm the disease. Virus isolation can be attempted from swabs of the nose, throat, or eyes; semen, placentas, or fetal tissue; and blood samples. However, the most common method of diagnosis is testing blood for the virus' neutralizing antibodies that cause EVA. While the presence of these antibodies alone does not indicate active infection, it does indicate EVA exposure has occurred. Very high levels of antibodies on a single sample or a rising antibody titer from paired blood samples collected 14 to 28 days apart indicate active infection.

Treatment

While there is no specific treatment for EVA, treatment should include rest and in selected cases, antibiotics, which may decrease the risk of secondary bacterial infection. Adult horses recover completely from the clinical disease. However, the virus commonly persists in the accessory glands of recovered stallions, so these carrier stallions continue to shed the virus for years and remain a significant source of infection.

Prevention and Control

Fortunately, there is a way the industry can work to prevent and control EVA. A safe, effective, and low-cost avirulent live virus is now available. Combining this vaccine with isolation of the vaccinated animal from noninfected horses can prevent the spread of EVA.
Since properly vaccinated EVA-negative stallions do not become carriers, all EVA-negative colts less than 270 days old should be vaccinated. The vaccine is not approved for use in pregnant mares.

Blood samples for EVA testing should be collected from all horses before breeding, and virus isolation should be performed on imported semen before use. Strict hygiene and disinfection of instruments and equipment are essential to minimize spread of the virus. EVA-negative mares should be bred only to EVA-negative, noncarrier stallions.
 

If blood test results are positive in a stallion, but there is no official documentation of negative EVA status prior to vaccination, the stallion must be tested for the presence of a carrier state. Virus isolation can be attempted on the semen from two separate ejaculations, or by mating two EVA-negative mares with the stallion. Twenty-eight days after breeding, mares' blood should be tested for the development of the neutralizing antibodies to the EVA virus.

Carrier stallions should be bred only to EVA-positive mares or mares that are properly vaccinated. When breeding an EVA-positive or carrier stallion to an EVA-negative, vaccinated mare, isolate both horses for 24 hours after breeding to prevent mechanical spread of EVA from voided semen. If this is the first time the mare has been bred to a carrier stallion, she should be isolated from other horses for an additional 21 days due to potential virus shedding.

All vaccinated horses should receive yearly boosters to protect against infection and, for the stallions, to prevent the development of a carrier state. In a generation or two, these practices could all but eliminate the population of carrier stallions.
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Current information on animal diseases is also available on the Internet at www.aphis.usda.gov. All information contained in this article is from: http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_ahequineva.html and http://www.newmexicolivestockboard.com

 

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