Lying down in the wrong spot is a cow’s fatal mistake

Russ Daly

Getting to the dead cow took a fairly long ride.

It was a chilly November morning, and I was glad Glen’s side by side had a heater. Glen noticed this cow late the previous morning and called me out first thing in the morning. I was glad to oblige; it’s frustrating being asked why a cow died when you don’t get to see the cow, let alone perform a good necropsy.

Glen’s other cows, chewing on cornstalks and oblivious to the loss of one of their compatriots, watched us as we tooled along the edge of the field. There ahead of us lay a massively bloated cow, looking more spherical than rectangular. She was lying in the deep furrow at the field’s edge, on her side with her legs aimed up the gentle rise where the cornfield merged with a grassy hill.

“Glen, I think I know what happened, but I’ll open her up and make sure I’m not missing something,” I told the rancher as I dug my post-mortem knife out of my bag.

My exam revealed a healthy cow about four months pregnant with no visible problems elsewhere. Bloat was the immediate cause of death. When gas relentlessly builds up in a ruminant’s forestomach without an outlet, it squeezes the lungs and blood vessels so much the animal suffocates.

“Glen, I’m afraid she died from bad luck.”

Where the cow decided to lie down was her unlucky downfall. In the furrow with her back downhill was a position she couldn’t easily rise from. Struggling probably put her into an even worse position and her fate was sealed. Cows haven’t yet figured out how to roll over on their backs like horses can.

What we had here was a disruption in rumen physiology. Getting rid of the 10 gallons of carbon dioxide and methane the cow produces every hour requires the cow to burp. Normally this is no big deal: gas floats to the top of the rumen “vat” where the opening to the esophagus sits ready to serve as an outlet. This particular cow positioned herself (and her rumen) such that the opening to the esophagus was blocked with fluid. The gas couldn’t find its way out.

Should you find an obviously bloated cow like this in dire straits (severe difficulty breathing), the risk of death is great enough that you should consider extreme measures to relieve the pressure on the rumen. A length of hose run into the mouth and down the throat has a good chance of getting to the gas cap and letting it pass out the hose. A speculum (a short length of metal or heavy PVC pipe) placed into the mouth to run the hose into will prevent the cow from chewing up the hose.

But hoses and pipes are rarely available when you need them. This brings us to the “surgical” method of emergency bloat relief: puncturing the body wall and rumen with a sharp knife, allowing gas to escape out the cow’s side. This needs to be done on the cow’s left side (viewed when standing behind her), a hand’s-width or so behind the edge of the ribcage. It’s scary to carry out, but it just might save her life.

Luckily the vast majority of cows don’t put themselves in these situations. But I’ve been out on field investigations and taken calls from producers who have experienced this multiple times, raising the question of whether there are underlying factors that contribute to cows succumbing to “positional bloat.”

Pregnant cows are overrepresented in positional bloat cases: their increased abdominal fill makes it tougher to get up and down and exacerbates the effect of bloat. Cattle grazing hilly pastures or dry lots with lots of ruts and depressions are more prone than are flatlanders.

When multiple cases of positional bloating occur, a hard look at cow nutrition and body condition is warranted. Most cows have enough energy and strength to extract themselves from all but the stickiest situations, but pregnant cows in poor body condition, with extreme winter weather sapping their energy, often don’t.

Here's hoping all your cows have no such problems burping their way through the winter. If not, however, understanding what to look for, what to do in an emergency, and how to possibly prevent these problems, might be the difference between life and death.

Russ Daly

Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University.