04/09/2026
❗🌱Fog fever🌱❗
With the weather finally favourable for grass growth after the extended draught, be aware of the risk of Fog Fever in cattle
What is Fog Fever?
It's a condition absolutely unrelated to foggy weather, and will not cause a fever either!
Acute Bovine Pulmonary Edema and Emphysema is a severe, non-infectious respiratory disease that affects adult cattle when they are abruptly moved from dry feed to lush, high-protein pastures
What causes it?
Fog Fever is caused by the rumen being unable to adapt to the sudden change in diet. It usually occurs 5 to 10 days after moving cattle from poor, dry, or over-grazed forage to fast-growing, green pasture.
High amounts of the amino acid L-tryptophan in the lush grass are broken down by rumen microbes into a toxic compound called 3-methylindole (3-MI).
Absorbed into the bloodstream, 3-MI damages cells in the lungs, causing severe fluid build-up (edema) and trapped air (emphysema)
What are the symptoms?
*Difficulty breathing with extended head and neck
*Grunting on expiration
*Coughing
*Frothing at mouth
*Cattle do not normally run a fever!
*Anxiety
*Collapse
*Death
What is the treatment?
Unfortunately, there is no specific cure. Mild cases might recover, but severely affected animals can die withing a few days. Handling distressed animals can cause sudden death.
How to prevent?
🌱Graze pastures before they become overly lush and protein rich
🌱Limit grazing on these pastures to a couple hours a day for the first 10 days and slowly build this up
🌱Cutting the pasture immediately before turnout can help
