A necropsy on Medina Spirit, who won the 2021 Kentucky Derby, has shown no definitive cause of death, despite extensive testing.
Microscopic changes seen in various tissues were mild and did not point to a specific cause of death.
The swollen lungs and foam seen in his windpipe, as well as an enlarged spleen and congestion and mild bleeding in other tissues, are common in horses dying suddenly. They are all compatible with, but not specific for a cardiac cause of death.
The anti-ulcer medication omeprazole and the diuretic furosemide were detected in blood and urine samples, but this was consistent with the medication report filed with the California Horse Racing Board by the attending veterinarian.
No other drugs, heavy metals (including cobalt) or toxicants were detected in the colt. Thyroxine levels were below normal reference limits.
Degenerative joint disease was seen in the horse’s fetlock and elbow joints.
Medina Spirit, aged three, died on the morning of December 6 after collapsing near the finish line after completing a workout on the main track at California’s Santa Anita raceway.
The Bob Baffert-trained horse had last raced on November 6 last year, when he finished second in the Breeders’ Cup Classic at Del Mar.
Racing authorities promised a thorough investigation in a bid to determine the cause of death, including a detailed necropsy and toxicological tests.
The necropsy was performed by a diagnostic team with expertise in pathology, toxicology, and equine drug testing, who are part of the California Animal Health and Food Safety diagnostic laboratory system of the University of California, Davis, veterinary school.
Team members included Dr Francisco Uzal, Dr Javier Asin Ros, Dr. Monika Samol, Dr Robert Poppenga, and Dr Benjamin Moeller.
Medina Spirit’s body was transported to the California Animal Health & Food Safety’s San Bernardino laboratory for the necropsy, which included visual examination of the body and internal organs, and specimen collection for microscopic examination, toxicology, drug testing, and genetic testing. Specimens were also stored for possible future testing.
After the examination, Medina Spirit was cremated.
During the necropsy, the horse was examined for obvious causes of death and visually apparent abnormalities. Tissue samples were collected from the heart, lungs, liver, spleen, kidney, stomach, intestines, muscle, brain, spinal cord, testicles, and other glands, and were examined under the microscope for evidence of abnormalities.
Liver tissue was tested for heavy metals, anticoagulants, pesticides, environmental contaminants, drugs, and other products.
A blood sample was tested for thyroxine at Cornell University.
Blood, urine, and eye samples were screened for the presence of hundreds of substances, both legal medications and prohibited drugs, including, among others, erythropoietin, clenbuterol, and betamethasone.
Heart tissue samples were sent to the University of Minnesota and to the University of California, Davis, Veterinary Genetics Laboratory as part of ongoing research programs, in collaboration with the state racing board, investigating possible genetic causes of sudden death in racehorses.
After completion of all testing, the finalized report, including photographs and the results of all tests, was provided to the University of Kentucky’s Dr Laura Kennedy and the University of Guelph’s Dr Grant Maxie for independent review.
The process now continues with a further required review of the necropsy report required under California’s racing rules.
Veterinarian Dr Alina Vale will perform that review. Additionally, a safety steward and a member of the Board of Stewards will be assigned to participate. Their report will be published by the racing board.
Medina Spirit, from the first crop of Prontonico (by Giant’s Causeway) was born on April 5, 2018, in Ocala, Florida, and was bred by Gail Rice. His dam, Mongolian Changa (by Dynaformer son Brilliant Speed and from the Unbridled mare, Bridled), was initially unable to produce milk so Rice used stored colostrum until the mare’s milk came in.
He attracted little attention when he was entered in the Ocala Breeders Sale of January, 2019. There was only one bid and he sold for the minimum $US1000 to Christy Whitman, who later resold the colt to bloodstock agent Gary Young for $35,000 for Saudi Arabian businessman Amr Zedan at the Ocala July Two-Year-Old Sale. Zedan named the horse for Medina, his hometown and the second holiest city in Islam after Mecca.
After he went into training with Bob Baffert, he outshone his more expensive stablemates. He won his maiden race in December 2020 at Los Alamitos.
In May 2021, he bested a field of 19 in the Kentucky Derby at Churchill Downs, including unbeaten favourite Essential Quality, earning $US1.86 million for his efforts.
An international study found that causes of exercise-related sudden death in racehorses are similar across multiple countries. In that study, a cause of death was determined with certainty in about 53% of cases, a presumptive cause was established in 25%, and the specific cause of death could not be determined in around 22% of cases.
Research is continuing worldwide to better understand and prevent these deaths.