Medina Spirit’s necropsy was released yesterday and the results are inconclusive, although consistent with heart failure. The 3-year old colt died on Dec. 6 after working five furlongs at Santa Anita Park. The necropsy was conducted by veterinarians and forensic experts at the University of California, Davis. The report only states “sudden cardiorespiratory arrest/cardiac failure” as the suspected cause of death.

“A definitive cause of death was not established despite extensive testing,” the California Horse Racing Board said in a statement.

Medina Spirit had swollen lungs, foam in his windpipe and an enlarged spleen, all common when horses die suddenly, the board said. Those conditions are “compatible with, but not specific for a cardiac cause of death,” it said.

There were no unexpected — or illegal — drugs in the colt’s system, only omeprazole—used to treat ulcers—and the diuretic Lasix were detected in blood and urine samples. These findings were consistent with the medication report filed by the attending veterinarian.

A copy of the necropsy report can be found here. If you don’t want to see the photos, stop at page 13 and skip ahead to 32.

The mechanics of the necropsy, which included the collection and examination of tissue samples from the heart, lungs, liver, spleen, kidney, stomach, intestines, muscle, brain, spinal cord, testicles, and other glands. Additionally:

• Liver tissue was tested for various substances including heavy metals like cobalt, anticoagulants, pesticides, environmental contaminants, and drugs.

• A blood sample was sent to Cornell University to be tested for thyroxine.

• Blood, urine, and aqueous humor samples were screened for “hundreds” of legal and illegal drugs and substances, including erythropoietin (EPO), clenbuterol, and betamethasone.

• Heart tissue samples were sent to the University of Minnesota and to the UC Davis Veterinary Genetics Laboratory as part of ongoing collaborative research program with the CHRB investigating possible genetic causes of sudden death in racehorses.

The finalized report—including necropsy photographs and microscopic sections—were sent to experts at the University of Kentucky and the University of Guelph, Ontario, Canada, for independent review.

California officials said it is not unusual to reach an inconclusive necropsy result. They cited an international study of exercise-related sudden death in racehorses that found a cause of death was determined with certainty in about 53 percent of cases, a presumptive cause was established in 25 percent, and in about 22 percent the specific cause of death could not be determined.

Last year, 13 percent of the 71 racing deaths of thoroughbreds and American quarter horses in California were classified as sudden deaths.

The necropsy does not resolve whether Medina Spirit’s Derby victory will be allowed to stand. As a result of the pending investigation, trainer Bob Baffert has been banned from running horses in the Kentucky