Fistulated Cows: Why Some Cows Have a Hole in Their Side

Originally published 2017-03-06.

A fistulated cow, also called a cannulated cow, is a cow that has had a surgical opening made in its left side and fitted with a ring, or cannula, that leads straight into the rumen, the largest chamber of its stomach. The opening is closed with a removable plug. Through it, researchers can look inside, take samples of partly digested feed and measure how a diet works, and vets can take rumen contents to help other cows whose digestion has failed.

The cows in viral photos are not wounded animals with an untreated hole. They have a healed, managed port. Whether creating that port is acceptable is a real ethical question, and this page sets out what the procedure is, why it is done, what supporters and critics say, and where Thinking Humanity stands.

What the procedure involves

Cows are ruminants. Their stomach has four compartments, and the first, the rumen, is a huge fermentation vat that can hold well over 100 litres in an adult. Microbes in the rumen break down grass and hay that a human gut could never digest. Studying that process from outside the animal is difficult, which is why scientists began creating direct access to it nearly a century ago.

Rumen cannulation was first documented in 1928 by Arthur Frederick Schalk and R. S. Amadon at North Dakota Agricultural College. The method used today is broadly similar. The cow is fasted beforehand and operated on standing up and awake, with a local anaesthetic numbing the flank. The surgeon opens the skin and muscle behind the last rib, stitches the wall of the rumen to the skin so the two heal together, and inserts a flanged rubber or plastic cylinder that holds the opening in shape. A cap seals it between uses.

Animal rights group PETA cites a recovery period of four to six weeks. After healing, the cow eats, walks and grazes with the herd, as the photo below shows.

The close-up shows what the port looks like after healing: a smooth, amber-coloured ring set into the hide, with the rumen wall visible through the centre. The plug is removed only when samples are taken or material is transferred.

Why researchers and vets use cannulated cows

Most of what we know about how cattle digest feed comes from animals like these. A port lets scientists sample the same cow again and again, over hours or months, instead of slaughtering many animals to look at their stomachs once. Research using cannulated cows has shown, for example, how rumen acidity rises and falls during the day and how different feeds change the fatty acids the microbes produce. It has also been used to test treatments for rumen acidosis, a painful condition caused by too much grain.

The second use is veterinary. When a cow's rumen stops working because of illness, surgery or poisoning by toxic plants, a vet can take a few litres of healthy rumen contents from a cannulated donor cow and pour them into the sick animal, restoring its microbes. This is called transfaunation. A 2014 review found it helpful for indigestion linked to illness, after surgery for a displaced abomasum and after toxic plant ingestion.

Cannulated cows also appear at university open days and agricultural shows, where visitors can feel inside the rumen. Those demonstrations are one reason photos of them spread so widely online.

The case against: welfare and purpose

Critics argue that cutting a permanent opening into a healthy animal is hard to justify, however well it heals. Their main points are:

• Pain and stress. The cow is awake during major abdominal surgery, and recovery takes weeks. Local anaesthesia reduces pain during the operation but does not remove the stress of restraint and handling.
• Lifelong maintenance. The port must be cleaned and checked for leaks and infection around the edge for the rest of the animal's life.
• Who benefits. The research mostly serves the beef and dairy industries, helping them feed animals more efficiently before slaughter. PETA argues that the cows endure the procedure for the profit of the very industry that will kill them. The New Zealand Anti-Vivisection Society has called the practice cruel.
• Alternatives exist. In much of Europe, fistulating cows to supply rumen fluid for sick animals is considered unethical and is not practised. Vets there use a rumen-fluid collector, a tube passed through the mouth, which can usually draw off around five litres and is reportedly well tolerated.

The case for: what supporters say

Animal scientists who work with cannulated cows say the animals recover well, live for years and often become calm, well-handled members of research herds. They argue that one cannulated cow, sampled many times, replaces large numbers of animals that would otherwise have to be slaughtered for the same information. Better knowledge of digestion also feeds into animal health: preventing bloat and acidosis, reducing the methane cattle produce and making diets safer.

Supporters also point out that the operation is regulated. In countries such as the United States, Canada and Australia, research on animals has to be approved by institutional animal ethics committees, which review the surgery, pain control and long-term care.

Watch: how the cannula is used

This video shows a cannulated cow and how the port is opened to reach the rumen. Viewers can judge for themselves how the animal behaves.

Watching a vet reach into a living cow's stomach is unsettling for many people, and that reaction is worth taking seriously. It is also fair to note that the cow in such footage usually stands quietly and keeps chewing. Neither the discomfort of the viewer nor the calm of the animal settles the moral question on its own.

Common myths about fistulated cows

"Farmers do this to all cows to produce more meat or milk." They do not. Cannulation is mostly done at universities, research stations and some veterinary practices. The vast majority of cattle never have the procedure.

"The hole is drilled." Nothing is drilled. The opening is cut surgically and the rumen is stitched to the skin, so it heals as a sealed tract.

"The cows are in constant agony." There is no good evidence for constant pain once healing is complete, but the surgery itself and the recovery are real burdens, and the port needs lifelong care. That is the honest core of the welfare debate.

"It is the only way to help sick cows." Not so. Rumen fluid can be taken through the mouth, which is standard practice in much of Europe.

Where we stand

This site's view, held since we first covered the subject in 2017, is that animals are not machines to be modified for our convenience. We think the burden of proof belongs with those who want to operate on healthy animals, and that where gentler methods such as oral rumen collection work, they should be preferred. Research that genuinely reduces suffering, such as preventing painful digestive diseases, is easier to defend than research aimed only at squeezing more output from each animal.

You may weigh it differently. The useful questions to ask are the same either way: what is each study for, could it be done without surgery, and who checks on the animals afterwards?

Sources: Wikipedia: Fistulated cow; PETA: Fistulated (cannulated) cows. Story first shared by Minds via Amazing Oasis.