Bloat is one of the few calls we get which is an absolute, full-blown emergency. It happens when a cow eats lush feed (usually lucerne or legumes), which froths up in the rumen, preventing her from burping. The gas builds quickly, and the cow begins to blow up like a balloon. Soon, she's struggling to breathe. There's an extremely narrow timeframe to relieve the pressure by stabbing the rumen (remember: left side, and use a knife with a hilt if possible) and drenching with oil, and it's rarely just the one cow that is affected.
So, we get the call. Heart thumping, you collar the vet student, grab some paraffin, and dash out to the car park. On the way to the farm, you're pushing the speed limit and in your mind the problem becomes bigger and bigger - how many cows are affected? Does the farmer know what to do? Who will be around to help? How many are going to be dead by the time you get there - maybe the whole herd?
You pull up next to the dairy and dash over to the crush, panting and puffing, with trochar in hand.
Strangely, there doesn't seem to be many dead or dying cows around.
Instead, there's just the one cow standing in the yards, chewing quietly. Her left side is blown up, but she doesn't look particularly unhappy. The farmer walks up scratching his head. What's going on here?
You breathe a sigh of relief. It's vagal indigestion.
Vagal indigestion is uncommon but easy to diagnose. The cow looks like a 'papple' when viewed from behind. Both lower quadrants are usually bloated, and the left upper quadrant of the abdomen is bloated (apple), while the right upper quadrant is normal (pear). Because this happens gradually, the cow has time to adapt to the situation and is unlikely to be in respiratory distress (gasping for air). It's still worth checking that there are no other problems, but diagnosis is generally straightforward.
Unfortunately, treatment isn't quite so simple.
Usually, the cause is damage to the vagus nerve, which runs from the brain and along the oesophagus, all the way to the rumen. It's one of the longest nerves in the body. This exposes it to a lot of potential problems, including drenching injuries, internal abscesses, infection in the chest or abdomen, hardware disease (wire in the guts), cancer, twisted stomach (left displaced abomasum [LDA] or right displaced abomasum [RDA]), and chronic pneumonia. Occasionally, it's caused by something unrelated to the nerve, like a small growth stopping food from moving out of the abomasum, or a heavy twin pregnancy.
Whatever the cause, improper emptying causes a build-up of gas and fluid in the rumen, resulting in swelling of the left abdomen.
It can be difficult to tell what the original cause was without further testing (with the exception of pregnancy). Some of the causes are very treatable - pregnancy, for example, can be cured by calving. Some, however, are completely incurable, like cancer or scarring from injuries.
My preferred approach is to provide short-term respite by releasing the gas with a stomach tube or a wide-bore needle (this isn't without its risks - I usually clean and prepare the area first, and avoid stabbing too many times). You can almost hear the cow giving a sigh of relief when you do it.
Then, if I suspect hardware disease or cancer, I'm afraid there's not much more to be done.
However, if the cow is not terribly old or seems otherwise healthy, I like to trial a course of antibiotics and anti-inflammatories to cover infectious or inflammatory problems. If there's no response, then I reason that the cause must be irreversible.
For these cases, a trochar can be placed, allowing farmers to release pressure regularly until the cow has made it through calving or a withholding period. On a few occasions, I've left a stomach tube with the farmer so that he can deflate the cow as necessary (with the expectation that I'll get my tube back). This is a time-consuming exercise, so not everyone opts for it.
For highly valued cows, we can try exploratory surgery to find the cause, with a view to correcting it if at all possible. This might work for very small lumps or abscesses obstructing the flow of food, but we can do nothing for problems in the chest or neck. Also, adhesions or hardware disease might be diagnosable this way, but cannot be fixed -- even with surgery. So it can be hit or miss (usually the latter, in my experience).
Hopefully, this helps to differentiate frothy bloat from vagal indigestion. Bloat is fast and causes respiratory distress; vagal indigestion is gradual. Bloat affects multiple cows whereas vagal indigestion usually just the one. Knowing this may help to reduce unnecessary stabbings -- which are never fun to fix.
*Ee Cheng Ooi is a cattle veterinarian and fertility researcher working with the animal health team at Dairy Australia. All comments and information discussed in this article are intended to be of a general nature only. Please consult the farm's vet for herd health advice, protocols and/or treatments that are tailored to a herd's particular needs.
This story first appeared on the Australian Dairyfarmer