Rachel Liepman, DVM, DACVIM, of Cave Creek Equine Sports Medicine & Surgery in Arizona, said one of the most common respiratory issues in performance horses is allergies. She also said there are concerns with upper respiratory dynamic versus static issues, and lower respiratory problems such as EIPH and asthma. Liepman added in the problem of shipping fever, especially with show horses.
In this episode of the Disease Du Jour podcast, Liepman talks about these issues, including clinical signs, diagnoses, treatments, complications and client management (especially concerning environmental management of horses).
Liepman said allergies can be unique to each horse. She said some have runny eyes or hives, then get respiratory signs. “Getting a good history is important,” she stressed. “As is a thorough physical exam that covers history of cough or nasal discharge. Is nasal discharge in one or both nostrils and how frequent. Are signs seasonal? Has the horse had a fever? Do you monitor temperature? Does the horse cough after exercise? Is he ‘sour’ at the gate? Has he ever bled from the nostrils?”
In high-speed event horses such as race horses or Quarter Horses, you night have to check to see if they have EIPH (exercise-induced pulmonary hemorrhage). For example, not all horses that bleed actually have blood come out the nose. And not all blood at the nostrils is caused by EIPH.
For diagnosing horses with allergies, you need to get a history of feed, housing, hay, bedding and whether signs are seasonal, Liepman advised. While there are a couple of ways to diagnose allergies, Liepman starts with a “baseline clinical/pathological evaluation to make sure the horse is normal and we aren’t missing subtle signs of something else.”
The diagnosis testing will depend on the client. Tests could include imaging the lungs, ultrasound to see evidence of disease, plus or minus X-rays, she said.
Liepman said you can do serum and intradermal skin testing—which she said is the gold standard. “Testing can be customized by the region,” she noted. “In my clinical experience, I prefer intradermal testing, although I have seen good results in serum testing and treatment.”
Tests can help eliminate something in the feed or environment
Treatment can be immunotherapy (AKA, “allergy shots”) or exposure therapy.
Liepman said horses with asthma often have a history of coughing at the beginning of exercise and nasal discharge after exercise. “From there I get baselines on clinical pathology,” she said.
She often uses ultrasound and X-ray examinations of horses suspected of having asthma. “I tell students and clients that those give you two different results,” she said.
She went on to discuss what she can see on each modality, and what you can’t see. Liepman also talked about pulmonary testing and bronchoalveolar lavage (BAL).
Upper Respiratory Issues: Dynamic vs Static
Liepman talked about the different histological and examination findings for horses with upper respiratory issues. Those problems could include left laryngeal hemiplegia (roarers), which causes horses to make sound during exercise and toss their heads due to difficulty breathing.
Some horses have dorsal displacement of the soft palate (DDSP), which also obstructs the airway. Another issue is epiglottic entrapment.
An upper respiratory endoscopic exam is useful in the above-mentioned types of issues.
Liepman said shipping fever usually causes clinical signs 24-72 hours after a horse gets off a trailer. “There are some things we can do to help, including vaccinating for flu/rhino a couple of weeks before we trailer a horse,” said Liepman.
She also noted that horses that are tied in trailers while traveling are unable to lower their heads to get rid of inhaled dust, which “seeds things deeper in the airway.”
Liepman reminded veterinarians that horses can get “so sick so fast” that it is important to jump on the clinical signs of fever, lethargy and nasal discharge after travel.
One tip Liepman gave was that veterinarians know it is harder to hear the heart beat on the right side of the horse, so if you hear it easily, you probably have fluid in the lungs.
She said SAA (serum amalyoid A) testing is useful in these cases.
“I think the biggest thing to teach a client is that horse is breathing in its environment, which is not so different from us,” she said. She added that hay nets and round bales of hay are prime culprits of adding dust and molds to a horse’s environment.
She advised drilling down into the horse’s environment with clients that have horses experiencing upper or lower respiratory airway issues. “Look at how they feed, bedding type…try to devise strategies,” she advised.
“I try to be understanding of the owner,” she said when it comes to management changes. “The clients like their vet trying to be a team and to know there are options.”
“It is uncommon to involve an internist,” said Liepman, “but it can be helpful.” She noted that general practice veterinarians can get the characteristics of what is going on, and that an internist can support what the veterinarian wants to accomplish, “then turn the client back to you.”
About Dr. Liepman
Liepman is an internal medicine specialist who has extensive training in sports medicine as well as being an avid equine enthusiast herself. She attended veterinary school at Michigan State University, completed an equine internship with BW Furlong and Associates in New Jersey, and underwent advanced training to obtain her Master’s degree and certification with the American College of Veterinary Internal Medicine from The Ohio State University. Liepman grew up on the East Coast and in the Midwest with Thoroughbred racehorses, and she still competes with her jumper mare.