Sunday, January 10, 2016

How Improved Veterinary Science Led to Discovery of Salmonella

By Matt Richmond, Originally published on April 27, 2015

Today is Cornell University’s 150th anniversary. Its charter was signed in Albany in 1865. One of the school’s founders, Ezra Cornell, was a farmer and made veterinary science a priority. This is the story of the career of the first doctor of veterinary medicine to graduate from Cornell.

Daniel Salmon was 18 years old in 1868 when he traveled to Ithaca to go to college. Today the College of Veterinary Medicine at Cornell is a sprawling maze of labs, barns and hospitals. Back then it was much simpler.

“There was just one academic building in the very beginning,” says Donald Smith, former dean of the College of Veterinary Medicine. “Cascadilla Hall was there for students and faculty as a residence and there was very little else except a farm, a working farm.”

Salmon’s doctorate from Cornell University was the first awarded in the U.S. The bacteria salmonella was named after him, though his assistant Theobald Smith actually discovered it. And Salmon helped found veterinary colleges in Washington, D.C., and Uruguay. He also developed the first federal meat inspection system in the U.S.

When Salmon’s career reached its peak 30 years after arriving at Cornell, it came right as the  profession began to change, too. Smith says at first veterinarians were in the cities and made sure horses could get people where they needed to go.

“And the Civil War was a period when they lost probably a million horses and mules from trauma, but mostly from starvation and disease,” says Smith.

The theory that disease is caused by microscopic germs was developed in the 1870s. Then Louis Pasteur first tested his rabies vaccine in 1885. And as Salmon’s career developed, veterinarians began to move out of the cities to work with farmers, treating diseases.

Today, at a state lab run by Cornell, technicians work on samples from farm animals. They load slides with those samples to see what microbes are in there.

“So within ten minutes we’ll know if we have a salmonella or not and we can report that back to the client immediately,” says lab manager Rebecca Franklin-Guild.

Obviously, finding salmonella for the first time was much trickier. They had simple microscopes in Salmon’s day. They had to find what they thought could be a pathogen in a sick animal. Then they had to inject it into a healthy animal. And if that animal got sick, then they knew they had found a disease. And when salmonella was found, Salmon and his assistant were actually looking for a virus called hog cholera.

“We sort of envy them,” says microbiology professor Craig Alltier. “They were able to just do whatever they wanted to do to try to diagnose disease and advance science.”

Alltier is still studying salmonella today, but he focuses on the genes that let this single-celled organism figure out when it’s inside a host’s intestine.

“Imagine this bacterium. Here it is living in your aunt’s egg salad at the church picnic. Suddenly, it’s eaten, it’s taken into the body, it’s in your stomach, it’s in your intestine,” says Alltier. “The bacteria has to change and adapt very quickly to those sorts of conditions.”

Salmon’s research assistant first identified the bacteria in 1885. But Salmon’s career didn’t end there. Around the same time, he put in place a federal meat inspection program at the Bureau of Animal Industry. He left the federal government under a cloud in 1905. Salmon was a part-owner of an ink company doing business with his department.

He went on to found a veterinary school in Uruguay and ended up working in Montana. And 150 years after he entered school, his name is revered as one of the earliest scientists to focus on diseases that moved from animals into humans.

Image: Dr. Daniel Salmon, the first doctor of veterinary medicine from Cornell University.



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