The debate of race-day furosemide has once again taken over the websites and social media accounts of our industry. Trainers tell us how inhumane it would be to not allow a horse that has experienced exercise-induced pulmonary hemorrhage (EIPH) to receive furosemide (Lasix). The public does not understand why we tell them that horses love to run on their own, yet we give more than 95% of horses a drug on race day that certain groups claim that horses need to be able to run.
Earlier this year the second of two projects funded by Grayson-Jockey Club Research Foundation that examined furosemide administration at 24 hours prior to a race was published in the Journal of Veterinarian Internal Medicine, and Grayson believes we have a way forward.
This project examined fit Thoroughbreds that were known to be clinical EIPH patients – horses that are known bleeders. The research started in the clinic on the treadmill with all horses receiving one of seven different treatments, with the 250 mg dose representing the traditional low dose allowed by regulatory authorities and the 500 mg representing the traditional high dose:
1. Placebo (saline)
2. Conventional (low-dose, 250mg, 5ml) furosemide four hours pre-exercise
3. Controlled water access only with no medication (maintenance water access for 24 hours pre-exercise)
4. Low-dose furosemide (250mg, 5ml) 24 hours pre-exercise with free access to water
5. High-dose furosemide (500mg, 10ml) 24 hours pre-exercise with free access to water
6. Low-dose furosemide (250mg, 5ml) 24 hours pre-exercise with maintenance water access
7. High-dose furosemide (500mg, 10ml) 24 hours pre-exercise with maintenance water access
From all seven of these treatments, the one that was clinically relevant and showed the least amount of blood from horses that suffer from EIPH was treatment No. 6, low-dose furosemide given at 24 hours pre-exercise with maintenance water.
After the clinical trial, the horses returned to the racetrack, trained for one month, and then ran in two simulated 1,100-meter (slightly longer than 5 furlongs) races. The horses received treatment No. 6, the most effective treatment as defined by clinic trial in one race, and a saline control in the other. The races were separated by two weeks of training.
Results from the simulated races show that for horses that are known bleeders, the low-dose furosemide administered at 24 hours prior to post with maintenance water has great promise as a replacement to the current four-hour administration of furosemide.
These findings are encouraging and indicate that Lasix is capable of attenuating EIPH for a longer duration than traditionally believed.
Here's a link to the study: ncbi.nlm.nih.gov/pubmed/31397944
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