The term ketosis is used to refer to a spectrum of conditions associated with low blood sugar and intense fat mobilisation resulting from reduced food intake. In conditions of persistent low blood sugar the liver attempts to produce sugar from fat. This process involves production of ketones, which in turn have the potential to result in suppression of appetite depending on the levels produced. The result may be persistent inappetence, inanition and death.
The trigger, persistent low blood sugar, is brought about by feed deprivation, inadequate energy in feed, or inappetence caused by stress or concurrent disease such as displaced abomasum, metritis or lameness.
Any class of animal in any physiological state may be affected. Animals that are older, fatter, pregnant or lactating, are at higher risk. Ewes and does that are pregnant with multiple foetuses are at higher risk. In heavily pregnant animals the disease is usually irreversible and fatal, while lactating animals may self-cure by reducing milk production. Some animals may become persistently inappetent and die from inanition. Depletion of rumen flora may be a complication in later stages in some animals and this may explain some treatment failures.
There are numerous potential stressors during the export process that may predispose animals to ketosis including mixing of cattle, introduction to unfamiliar environments, periods of feed or water deprivation during transport and handling, and dietary changes from farm to assembly depot to ship. Older, well-conditioned cattle entering the export process that become shy feeders at sea and at destination, may be suffering from ketosis.