b'SPONSORED BYLguillette said. Common signs of an up-per airway issue include: Abnormal respiratory noise; Furosemide Administration Times Tested Exercise intolerance; and Thoroughbred racehorses in North America often receive furosemide as a preventive forCoughing. exercise-induced pulmonary hemorrhage (EIPH, bleeding into the lungs). An estimated 44-Lower airway problems are often char- 75% of Thoroughbred racehorses suffer from this condition, which can adversely affect both acterized by: health and performance. Typically given four hours before a race, furosemide is currently theCoughing; only proven preventive treatment available. Nasal discharge, usually bilateral (fromUnder the pending Horseracing Integrity Act of 2017 (HR 2651), race-day furosemide both nostrils) and mucousy; administration might be banned due to concerns that it might mask illegal substances. Exercise intolerance; andIn anticipation of this legislation, researchers from the University of California, Davis,Labored breathing at rest. looked at furosemides ability to reduce EIPH in Thoroughbred racehorses when adminis-Studies have shown that owners aretered 24 hours vs. four hours prerace. Anecdotal reports suggest that administering the drug a good and reliable source for observ- 24 hours prerace might be as effective as race-day administration in decreasing EIPH sever-ing changes in their horses respiratoryity. Associate professor Heather Knych, DVM, PhD, Dipl. ACVCP, presented their findings.signs, Lguillette added.The team used 15 client-owned Thoroughbred racehorses, both male and female, ages 2 Specifically, researchers found thatto 4, whose EIPH status was unknown. They randomly assigned horses to one of three treat-owners are better than vets at detectingment groups: 250 mg of intravenous (IV) furosemide 4 hours before exercise, 250 mg of IV changes relating to their horses cough- furosemide 24 hours before exercise, or 5 mL of 0.9% IV saline as a control. They restricted ing, he said. One study that showed: horses water access four hours before a five-furlong simulated race on a synthetic or dirt Horses that cough frequently ortrack. All horses underwent a two-week washout period before moving to the next treatment.constantly and during exercise areThe researchers noted a significant difference in EIPH scores after four-hour and 24-hour more likely to have severe airwayfurosemide administration. When horses received furosemide four hours before exercise,nflammation; and 93% had a zero EIPH score (no blood detected in the pharynx, larynx, trachea, or main-istream bronchi) one hour post-exercise versus 60% when furosemide was given 24 hours Horses that cough more frequently atbefore exercise. Sixty-nine percent of the saline-treated horses had a zero score.the start of exercise are likely to haveAn investigator blinded to the treatment also performed bronchoalveolar lavage (BAL) moderate to severe inflammation. and counted the number of red blood cells (RBC) in the BAL fluid. Horses receiving furose-I think it is therefore important to notmide four hours before exercise had significantly fewer RBCs in their BAL fluid than when ignore coughing observed at the begin- they received saline, but there was no significant difference between saline and 24-hour ning of exercise, Lguillette said.furosemide treatment. After evaluating clinical signs, the vet- Knych cautioned that the limited sample size and broad range of horses athletic ability erinarian has several diagnostic options: might have impacted treatment effect. However, she said, the results suggest furosemide is Endoscopy Static (at rest, in a standingeffective for reducing EIPH severity in Thoroughbred racehorses, but any reports that its just horse) and dynamic (during exercise, asas effective when administered four or 24 hours prerace are unfounded.Clair Thunes, PhDseen in the photo to the left) upper airway endoscopy can help diagnose obstruc-tions, Lguillette said. Such issues canto diagnose inflammatory disease. he said. They include bronchoprovo-include laryngeal hemiplegia (roaring),Sampling to detect inflammation Vet- cation tests (to assess the respiratory dorsal displacement of the soft palate,erinarians can collect a variety of samplessystems response to bronchoconstrictive and pharyngeal collapse.from the respiratory tract, Lguilletteagents) and measuring VO 2 max.Upper and lower airway endoscopy cansaid. These include tracheal wash and/ Diagnosing pulmonary pathologies also show evidence of EIPH, mucous ac- or bronchoalveolar lavage (BAL) samplesin athletic horses can be challenging and cumulation (due to lung inflammation),(flushing saline into the windpipe andshould start with a good documentation of and pharyngitis (pharynx inflammation). drawing the wash back up with aclinical signs, Lguillette said. The inter-Thoracic ultrasound Most useful forsyringe, or lavaging a lung with sterilepretation of ancillary tests can be difficult assessing the lung surface and diagnosingfluid before drawing it back out again,if a good technique is not used properly. pneumonia and related issues, ultrasoundrespectively). Practitioners examine both of the horses chest can also reveal evi- types of samples under a microscope toConsider History, Environment When dence of EIPH, Lguillette said. detect signs of inflammation. LguilletteManaging Equine AsthmaRadiographs Although difficult to per- said BAL analysis is the more reliable ofOn the surface, managing equine asthmaincluding RAO, a chronic condi-form on full-sized horses in the field, duethe two for detecting lung inflammation. to the lungs large size, X rays can helpHowever, he added, it isnt always clear- tion common in older horses, and IAD, vets see the deeper lung structures, alongcut, because some horses have persistentoften seen in younger equine athleteswith evidence of EIPH and pulmonaryinflammation even after treatment. might not seem complicated: Modify nodular fibrosis, he said. However, theyLung function testing These tests arethe horses environment and treat, when lack the sensitivity (the probability thatdifficult to perform in the field and areneeded, with corticosteroids and broncho-results will be correctly positive) neededmost commonly used in research settings,dilators. In reality, it can be challenging.March 2018THE HORSE AAEP Wrap-Up TheHorse.com/AAEP2017 A51'