A Toronto man is dead after a cat bit him on the right thumb—but the cause is so rare that doctors wrote up a case study in the World Journal of Clinical Cases warning other physicians to be on the lookout for the unusual cascade of events.

Animal bites are common, and the reason for some 330,000 annual US ER visits, with those attending doctors "acutely aware of the skin and soft tissue infections that can arise from mammalian bites," the researchers write.

A course of antibiotics tends to do the job, preventing a bacterial infection or at least stopping its spread. But in this case, the bacteria Pasteurella multocida, which lives in many pets' mouths, caused a 4-inch-wide aneurysm in the abdominal section of the man's aorta (the large vessel descending from the heart to the abdomen) that ultimately ruptured.

A portion of the aorta was fixed using a tube graft, but 13 days later he developed septic shock and died. When the man's wife mentioned—upon the 68-year-old's admission to the hospital—the four-week-old cat bite whose local infection had since healed, doctors dismissed it as the cause of his symptoms, which included elevated heart rate, low blood pressure, abdominal pain, and sudden weight loss.

"Sometimes as physicians we roll our eyes at information that seems to be extraneous," study co-author Dr. Dennis Cho tells the Toronto Sun.

"Only looking back did we realize this was probably the key to unlocking the true diagnosis." The doctors note the man's heavy drinking likely caused him to be immunosuppressed and upped his risk of long-term complications from the bacterial infection.

And CBS News reports on the highly unusual case of a woman who suffered sepsis after her dog simply licked her. (This cat lick was blamed for a woman's blindness.)

This article originally appeared on Newser: A Man Was Bitten by a Cat. 6 Weeks Later, He Was Dead

More From Newser