Bloat is relatively common, particularly in spring. It’s far more common in cattle than other species, and milking cows are most often affected, particularly young cows.

What are the signs of bloat?

  • In bloat, the rumen swells. This can be seen as distension and then a large bulge in the abdomen in the left flank area behind the rib cage in front of the hip where there is normally a depression.
  • The cow will stop eating and become restless; she may bellow, repeatedly try to defaecate or urinate and regurgitate boluses of herbage. Her breathing will become rapid and more laboured, maybe with the mouth open and tongue protruding. She may groan and grind her teeth because of the pain and discomfort.
  • If she gets worse she will become staggery, her mucous membranes (lining the mouth and nose and eyes) will become cyanotic (pale blue), she will go down, develop convulsions and die or asphyxiation and heart failure.
  • Sometimes it may take only 30 minutes from access to rapidly-growing clover-rich pasture to death.


  • Early treatment of bloat is usually successful. If treatment is left until the cow is recumbent, the outlook is not good.
  • If bloat is spotted early, the cow should be taken off pasture and given proprietary anti-bloat or anti-foaming agents by mouth. These act by breaking down the foam in the rumen.
  • In an emergency, 100 ml of vegetable oil, or 250 ml cream, or 1 litre of milk may do the trick.
  • A little gentle exercise may help break down the foam and make the animal start to belch - this is a very good sign!
  • When the bloat is severe and the cow distressed, you should call your veterinarian right away. The vet may need to operate on the rumen to release the pressure caused by the foam.
  • If the cow is very distressed and gasping with head extended and tongue protruding and your veterinarian is not available, you may need to resort to an emergency rumen puncture operation. This is not for the faint-hearted and should only be a last resort. Even then, it’s best to speak to your veterinarian first to make sure it’s the best thing to do.
  • The emergency operation involves plunging a sharp pointed knife into the distended rumen and making a short incision into it. Sometimes the gas will explode outwards but it may be necessary to scoop the excess stable foam out by hand. Oils like liquid paraffin or antifoaming agents like pluronics should be added to the rumen contents, then the site should be cleansed and sutured like a standard operation site.


  • If you have only lush clover-dominant pasture, don’t put cows onto it when they are hungry. Give them hay or concentrates first. Hungry cattle will gorge and may develop bloat.
  • Anti-foaming agents can be sprayed onto risky pasture before it is grazed.
  • If they are on risky pasture, cows can be drenched twice daily (eg at milking time) with proprietary anti-bloat substances (that often contain pluronics or detergents or alcohols).
  • Some antibloat treatments can be given in the drinking water, but this may be insufficient in wet weather when the cows may not drink as much.
  • A combination of drinking water medication plus once daily drenching may be a practical approach.
  • You could dose your cows with long-acting (controlled release) antibloat capsules, and these have the advantage of lasting for 100 days or more.
  • You could provide anti-bloat blocks and licks.