Holey Cow: The Wonderful World of a Fistulated Cow

Cornell's current fistulated cow, Blossom. / Courtesy Cornell.


Behind every successful cow are millions of gut microorganisms — mostly bacteria, protozoa, and some fungi. This bastion of bugs that resides in a cow’s 20-gallon rumen are ultimately responsible for digesting all the plant material the bovine consumes.

Being the quintessential symbiotic relationship — the cow supplies the bugs with nutrients and the bugs convert cellulose into usable energy for the cow — it also works the other way: when the cow gets sick, the bugs get sick, too. Then they die. And no gut bugs eventually means no cow.

Transfaunation — the act of taking microbes from one source and putting them in another — can be a literal lifesaver when it comes to a bovine bellyache. And how does one go about retrieving such a sample? By creating a one-stop shop for your sick cow’s gut flora needs. Designated donor cows with a surgically installed port allow access to the rumen from the outside.

Placing a rumen fistula — the medical term for a permanent hole between an internal organ and the outside world — into a healthy cow for collection purposes is a relatively straightforward procedure and performed frequently at veterinary schools, according to Dr. Brian Aldridge, clinical professor and specialist in large animal internal medicine at the College of Veterinary Medicine at Illinois. “To put one in would take about an hour and a half,” he says.

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Rumen flora from a fistulated cow helps not only sick cows, but also sheep and goats because they share similar digestive systems.

Performed with the cow standing, local anesthesia is used and the rumen is surgically attached to the skin and body wall. Then, a cannula, essentially a tube, made of extremely durable, thick plastic is inserted to keep the surgically created hole between the rumen and the skin open yet sealed. A removable cap is included for easy access. After healing is complete in about four to six weeks, your brand new fistulated cow is ready to save lives.

“It’s amazing how important those rumen bugs are,” Aldridge says. “Not only are they important for digestive function, but also for how the animal feels.” These microorganisms in the gut produce vitamins and minerals necessary for the health of the cow.

“They are essentially a natural probiotic,” Aldridge says.

Rumen flora from a fistulated cow helps not only sick cows, but also sheep and goats because they share similar digestive systems. “Our vet school always has a fistulated cow,” Aldridge says. “The bovine GI surgery patients routinely get a transfaunation because it’s been shown that the recovery rate and return to appetite and milk production is much greater if you reestablish the gut flora.”

Sick farm animals and surgical patients aside, fistulated cows are also a staple in bovine nutrition research, since having a fistula makes it easy to sample rumen contents in order to study how different nutrients affect a cow’s digestive system. The cost of surgically installing a rumen fistula is about $300 and doesn’t affect the longevity or health of the cow, says Dr. Susan Fubini, professor of large animal surgery at Cornell University’s College of Veterinary Medicine. “The plastic cannulas themselves last forever,” she says. As for the fistulated cows, “They are without a doubt the happiest animals in our hospital.”

Aldridge agrees. “People have looked into the longevity of animals with a fistula and they do really well,” he says. The fistulated cow currently at University of Illinois is named Brooke. “Brooke’s been here for four or five years and she’s fine. If anything, she’s overweight and over-cared for.”

It’s no wonder a fistulated cow at a veterinary school is treated like bovine royalty. Rumen microbes, or the “liquor of life” as Aldridge calls it, are a hot commodity where there are sick ruminants around. Aldridge estimates Brooke helps at least one patient on a weekly basis.

The logistics of a rumen fistula are straightforward enough that these cows are common demos at vet school open houses. Just unplug the top, don a shoulder-length plastic sleeve, and in your arm goes into the rumen of a live cow.

Just unplug the top, don a shoulder-length plastic sleeve, and in your arm goes into the rumen of a live cow.

If you’re in there for therapeutic reasons instead of as a tourist, you can remove a couple of gallons of rumen contents without any negative impact to the donor cow. What you take is then kept warm — remember your sample contains live microbes that are accustomed to a cow’s internal body temperature — then run through a strainer and usually diluted with water before administration through an orogastric tube to a ruminant in need.

At the University of Illinois’ busy hospital, Aldridge says Brooke has never run out of rumen fluid. “It’s remarkable how quickly her supply turns around,” he says. “Sometimes we’ll take samples two or three days in a row, but she always has some. She hardly changes shape after we take that much out,” he jokes.

With biosecurity an eternal concern on farms, fistulated cows must be in good health and come from a historically healthy herd. Common GI diseases such as Salmonella can be transmitted between donor and sick cow through rumen contents, as well as other diseases such as Johne’s disease, a chronic bacterial disease of the gut.

“Disease transmission is always a risk,” Aldridge says. “However, we’ve never seen that as a complication. We try to keep the donor animal in relatively high health, and perform regular blood tests.”

Cornell’s current fistulated cow is named Blossom. “Before Blossom, we had Stella and Elsa,” Fubini says. It seems that much like a clean bill of health, an exceptionally cow-like name is a requirement before donning a portal to the rumen world.

As for the humans who care about these cows, they can wear their pride: a major company that sells rumen cannulas makes t-shirts emblazoned with fistulated cows and sheep. (Typically $15, they come free with a $500 cannula purchase.) But, maybe, don’t wear it to the human dinner table.

Holey Cow: The Wonderful World of a Fistulated Cow