Therapeutic Drugs Used for Doping of Race Horses

Literature Review on the Therapeutic Drugs Used for Doping of Race Horses research, By Mohamed Ahmed

Doping is the administration of performance manipulating drugs to improve athletic performance; depress performance, and mask inflammation and pain. This is a common aspect of the horse racing industry, whereby manipulating a horse’s performance has a significant monetary incentive. This is a practice that has been taking place since 480 BC, during Roman times, whereby the horse would be crucified. In the present day, racehorses are doped to enhance their probability of victory by enhancing their physiological capabilities. The drugs used in this case include bronchodilators, steroids, and NSAIDs. Tranquilizers and sedatives are, on the other hand, used to impair a horse to increase the probability of losing in a race (Keen et al., 2021).  Their impact on the race outcomes has led to their ban among racehorses and the anticipated severe side effects, especially with their interaction with other drugs and supplements. This information is relevant in the understanding of the impact of using therapeutic drugs on dope horses.  This literature review will relay and critically analyze the relevant recent research studies on therapeutic drugs used to dope racehorses, their benefits, side effects, and detection. 

Therapeutic drugs

Therefore, it is important to note that there are two types of drugs used in regulating the horse’s performance, namely, therapeutic medications and performance modifying substances. Therapeutic medications are used to alleviate pain and enhance the horses’ ability to heal. Therefore, they are powerful pain killers used along with potent drugs to enable an injured horse to train and even race. A common medication use to mask the pain is furosemide, a loop diuretic that causes the urine output to increase. It lasts for a short duration and has a rapid onset, which significantly reduces the chances of detection due to the induced high urine output (Tozaki et al., 2018). These drugs include opioids, albuterol, NSAIDs, and corticosteroids, primarily excreted through the urine. The furosemides are administered about four hours before the race time, reducing the risk of pulmonary hemorrhage due to exercise (Slifer, 2018). Therefore, it is clear that from the literature, the term therapeutic drugs in doping is used to refer to the drugs used to increase the horse’s endurance rather than increasing and reducing the physiological capacity of the horse. 

The furosemide’s mechanism of action directly acts on the horse’s renal tubular function inhibiting the reabsorption of chloride and sodium in the Loop of Henle’s ascending limb. The Na:K: Cl cotransporter regulates the inhibition of sodium and chlorine located on the liminal surface (Fragkaki et al., 2017). This increases their delivery to the distal tubule, leading to the increased isotonic urine production, which would occur through the equal concentration of osmotic. Due to this, sodium transportation to the lumen increases its hypertonic while reducing that of the interstitium, as the osmotic gradient causes the reabsorption of water in the nephron (Wilkin et al., 2017).  However, the literature is ambiguous on the exact mechanism of the prevention of exercise-induced pulmonary hemorrhage. It functions by decreasing the concentration of potassium plasma and the increase of the sodium, hydrogen, and chlorine ions’ rate of excretion. 

Furosemide use on horses has not only positive but also has negative unwanted side effects. One of the most common side effects is dehydration due to increased urinary excretion, which also causes electrolyte and blood volume reduction. This can lead to the horse’s susceptibility to muscle weakness which may lead to collapse and consequentially lead to injury. In addition, the overuse of therapeutic may lead to diarrhea, vomiting, and nausea (Slifer, 2018). To stop the adverse effects of the use of therapeutic medication in the United States, where there are multiple testing standards. One of the most common techniques is the Liquid chromatography-tandem mass spectrometry (LC-MS-MS) that uses equine plasma to test different classes of Furosemides.  In this process, solid-phase extraction (SPE) and triple, quadruple mass spectrometers are used (Moreira et al., 2021).

In conclusion, there is adequate literature on the therapeutic use of drugs the doping of racehorses. However, one of the key weaknesses of this literature is the use of “therapeutic.” In some studies, it refers to doping in the increasing and decreasing of the physiological capability of the horse and the masking of pain. However, it refers to the exclusive to refer in the masking of exercise-induced pulmonary hemorrhage.  This study will therefore focus on the therapeutic use of furosemide in horse racing. 


Fragkaki, A.G., Kioukia‐Fougia, N., Kiousi, P., Kioussi, M. and Tsivou, M., 2017. Challenges in detecting substances for equine anti‐doping. Drug testing and analysis9(9), pp.1291-1303.

Keen, B., Cawley, A., Fouracre, C., Pyke, J. and Fu, S., 2021. Towards an untargeted mass spectrometric approach for improved screening in equine anti‐doping. Drug Testing and Analysis.

Moreira, F., Carmo, H., Guedes de Pinho, P. and Bastos, M.D.L., 2021. Doping detection in animals: A review of analytical methodologies published from 1990 to 2019. Drug Testing and Analysis13(3), pp.474-504.

Slifer, P., 2018. A Review of Therapeutic Drugs Used for Doping of Race Horses: NSAIDs, Acepromazine, and Furosemide.

Tozaki, T., Karasawa, K., Minamijima, Y., Ishii, H., Kikuchi, M., Kakoi, H., Hirota, K.I., Kusano, K. and Nagata, S.I., 2018. Detection of phosphorothioated (PS) oligonucleotides in horse plasma using a product ion (m/z 94.9362) derived from the PS moiety for doping control. BMC research notes11(1), pp.1-5.

Wilkin, T., Baoutina, A. and Hamilton, N., 2017. Equine performance genes and the future of doping in horseracing. Drug testing and analysis9(9), pp.1456-1471.