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Veterinarians operating a large racehorse or sport horse practice should consider investing in an open plethysmography system to help diagnose inflammatory airway disease (IAD) and other pulmonary and respiratory problems, says Rose Nolen-Walston, DVM, Dipl. ACVIM.
New Products on Market for Treating IAD
Animal health companies have developed products and services to help equine practitioners diagnose and treat inflammatory airway disease and other respiratory ailments.
Idexx Laboratories of Westbrook, Maine, came up the Equine Respiratory RealPCR Panel so practitioners can submit one sample to test for four respiratory diseases.
“Equine respiratory disease is one of the most common and most challenging medical conditions that equine practitioners face day to day,” says Scott Moffitt, senior manager of equine sales and marketing. “Customers who have used this test have been very impressed with the fact that they can submit a single nasal swab as a sample and receive results on four different respiratory diseases within 48 hours.”
The panel encompasses four real-time PCR tests:
• EHV-1 and EHV-4 RealPCR
• Sequi RealPCR (includes culture ID)
• Equine Influenza Virus RealPCR
• Equine Arteritis Virus RealPCR
Click here for more information or call 800-621-8378.
On the market for three years, the VibraVM uses sound waves introduced through the nose to break up accumulations of secretions in the respiratory system for easy expulsion. As a bonus, a certain type of sound produced relaxes constricted airways.
VibraLung Inc. of Parker, Colo., introduced VibraVM after six years of research, development and testing. The acoustic airway clearance percussor is used for relieving congestion in horses and any other mammal with acute and chronic respiratory conditions, says Jim Medford, vice president of sales for VibraLung.
In its bronchodilator mode, the
VibraVM relaxes airway muscles, opening them for increased airflow. Results are usually visible immediately.
By clearing the mucus, relaxing and opening the airways and increasing airflow, VibraVM treatments give the horse the maximum blood oxygenation possible, helping it breathe easier and feel better, Medford says.
Chronic conditions may take a month or so to clear all the mucus, Medford says, with an ongoing maintenance program afterward.
“We introduced the VibraVM at AAEP three years ago,” he says. “We were not very well received because at that time we only had a few in the field and we did not have any science to back up our claims.
“This (past) year was very different. We had just finished a dairy calf study at Colorado State University vet school with good results and we are in the middle of a ‘heavy’ horse study at Purdue University vet school. We had great handouts for our race-horse protocol and our standard equine protocol that answered most of the normal questions.”
Larry Britt, DVM, of Plant City, Fla., has used the VibraVM in his large-animal practice for almost a year. “The machine is phenomenal,” he says. “I’ve used it on about 15 horses and had a 90 percent success rate. I wish we had had this machine long ago.”
Click here for more information or call 303-805-4597.
Trudell Medical International of London, Ontario, in collaboration with Cummings School of Veterinary Medicine at Tufts University, has introduced the AeroHippus Equine Aerosol Chamber (EAC) for use with a metered dose inhaler, or puffer, to deliver aerosol medication to horses.
The lightweight AeroHippus EAC treats inflammatory airway disease and recurrent airway obstruction. The portable chamber is placed over one nostril. Once the puffer is depressed, the chamber separates large particles from small, breathable particles and holds them suspended until the horse inhales, allowing for the delivery of medication to the lungs.
Martin Foley, Trudell’s vice president of research and development, and Andrew Hoffman, DVM, of Tufts, collaborated on the AeroHippus, which was in development for several years.
“The AeroHippus delivers up to three times more medication to the horse’s lungs than competing products,” Foley says. Hoffman’s radiolabeling tests proved that about 18 percent of the medication landed in the lungs, as opposed to about 6 percent delivered by a competitor’s device.
Trudell also manufactures the AeroMask Equine System and the Aero Eclipse II Breath Activated Nebulizer.
For more information, call 800-465-3296.
Open Pleth, developed by Ambulatory Monitoring Inc. of Ardsley, N.Y., helps veterinarians test for airway hyperreactivity with its pulmonary function testing tool and diagnose inflammatory airway disease.
“Before open plethysmography, plethysmography was closed,” says Tom Kazlausky, president of Ambulatory Monitoring. “That meant bringing a horse into a chamber for testing. This was often difficult.
“The open, mobile system can be taken right into the horse’s stall. And because this way is easier, we are hoping that the tests are conducted more often, with an end result of healthier horses.”
Open Pleth with Equine Flowmetrics computer software is a modification of whole-body plethysmography that avoids the use of an enclosure.
Flow measurement is made at the opening of the horse’s nares. Volume displacements at the body surface are measured using elastic sensors.
Click here for more information or call 800-341-0066.
IAD, which causes coughing and poor performance in many performance and racehorses, is associated with airway hypersensitivity, says Dr. Nolen-Walston, assistant professor of medicine at the University of Pennsylvania’s New Bolton Center.
“Normal horses don’t have the hyperresponsive or ‘twitchy’ airway that horses with IAD demonstrate,” she says.
Open plethysmography, a pulmonary function test, is non-invasive and can easily be performed on the farm, she says.
Nolen-Walston suggests leveraging the results of open plethysmography with information gleaned from other diagnostics when formulating a treatment plan. She usually performs lung function testing with a histamine bronchoprovocation (HBP) before the cytological examination of the bronchoalveolar lavage (BAL) cells.
“Both tests are important to form a correct diagnosis,” she says. “Something might be diagnosed with lung function testing and not the BAL, or vice versa. You could miss this important information if you give one test or the other.”
The BAL test is easy to administer in the field, says Benjamin Buchanan, DVM, Dipl. ACVIM, Dipl. ACVECC, of Brazos Valley Equine in Navasota, Texas. The lung wash “takes about $60 of equipment”; a diagnosis of IAD or heaves can be made on the relative proportion of cell types.
Inflammation of the airway is not the same in every horse, says Alessandra Pellegrini-Masini, DVM, Ph.D, Dipl. ACVIM, of the University of Georgia’s College of Veterinary Medicine.
BAL results reveal that some horses show an increase in neutrophils, associated with local inflammation, while others have elevated eosinophils or mast cell counts, both associated with allergy.
Treatment for IAD involves both systemic and inhalant therapies, based on the type of cells present in the sample.
The newest medication delivery device on the market for horses, Nolen-Walston says, is the Aero Hippus, a one-nostril equine aerosol chamber that can deliver either inhaled steroids or bronchodilators from a metered-dose inhaler.
“We are diagnosing IAD earlier,” Dr. Pellegrini-Masini says, “so treatment may be more effective.”
A wide range of anti-inflammatories and corticosteroids is used to treat IAD. Dexamethasone, prednisolone and Flovent are commonly prescribed. Bronchodilators such as CombiVent, clenbuterol, albuterol and ipatropium bromide are used as rescue therapy, Dr. Buchanan says. “They are not intended for long-term control.”
Mast cell stabilizers may be necessary to control the disease, he says. Also used are equine nebulizers, which deliver an aerosol medication.
Nolen-Walston advises practitioners to be aware of tachyphylaxis to bronchodilators in treating IAD. “Most models of asthma–in horses, humans and rats–show that Beta-2 agonists lose their efficacy if used for more than two to four weeks,” she says.
“Don’t rely on bronchodilators alone,” she says. “Use them with a steroid to prevent their effect from waning over time.”
Pellegrini-Masini says research finds that young horses’ BAL tests frequently show more mast cells. In older horses, it is usually true that the test will show more neutrophils.
The first significant indication that should trigger a test for IAD is poor performance and slow recovery after exercise and chronic cough. Pellegrini-Masini says studies found that in some warmbloods, the only sign that something is wrong with the horse may be a reluctance to work with its head collected.
Nolen-Walston concurs and says that when a warmblood flexes at the poll, the upper airway is restricted. In horses with IAD, often this combination of increased upper airway resistance with lower airway inflammation results in exercise intolerance.
“No one has ever proved a breed predilection to IAD,” she says, “although there are some families of Warmbloods who seem more susceptible.”
Pellegrini-Masini says clinical signs are worse in horses that live in a hot, humid environment. She says a low dose of Interferon-alpha effectively reduces inflammation, while a high dose is less effective. The interferon also reduces the intensity of the inflammatory response to pollutants and allergens.
She recommends using Interferon-a with other steroids and bronchodilators in severe cases of IAD.
Pellegrini-Masini says there has been no scientific evidence that IAD leads to recurrent airway obstruction or chronic obstructive pulmonary disease. “The syndromes are different, but they can overlap,” she says.
“There is a trans-Atlantic debate over whether IAD is infectious or non-infectious,” Nolen-Walston notes. “Most American researchers believe IAD to be non-infectious and that environmental triggers are the main cause. IAD is a treatable disease. Management means reducing the triggers that can cause problems.”
What Can Be Done
Environmental IAD can be cured, Pellegrini-Masini says, if horse owners make permanent changes for their animal. She says veterinarians should recommend that owners:
• Reduce dust, allergens and other toxins in the barn and pasture.
• Avoid using hay or straw for bedding. Wood shavings, shredded paper or cardboard are alternatives.
• Replace hay with a pelleted diet. “There are some good feeds on the market that provide the fiber the horse needs without dust,” she says. “Feed companies also have a formulation that combines hay and molasses specifically for horses with IAD and allergy problems.”
• Feed hay on the ground, in the natural position in which a horse grazes, not above his head in a hay net or rack. “Horses are designed to eat with their heads down. There is a natural flow to help mucus to clear,” she says.
• Allow horses to spend more time in a pasture. Some do much better when they are not in a stall or a barn.
Pellegrini-Masini cautions that owners are not going to get good results if their horse is the only one in the barn to use wood shavings. Environmental pollutants can affect the animal when other horses are fed hay or when allergen-filled bedding is changed.
“The horse’s entire environment must change,” she says.
Owners need to be involved with the diagnostic tests, Pellegrini-Masini says. “I show them what is abnormal with the lungs when I test the respiratory function,” she says. “Treatment choices are made with the owner to make sure they can keep up with the therapy at home.”
IAD frequently goes unnoticed in backyard horses and broodmares. It is usually diagnosed in performance horses–dressage, hunter-jumpers and racehorses.
Buchanan, of Brazos Valley Equine, treats a lot of IAD-afflicted Quarter Horse racehorses, Western sport horses and barrel racers. “I see barrel horses that have run on Thursday, Friday, Saturday and Sunday,” he says. “They’ve inhaled dirt from the arena and are having a hard time working and cooling off. It takes them a long time to catch their breath.
“Their samples are unique in the amount of dirt and minerals they show,” he says. “The saturation of the air in the arena is quite high. If we can break the cycle of inflammation, the horse can go back to racing.”
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