Acetonaemia also called ketosis, sweet breath, and hypoglycaemia, is a disease commonly seen either in high producing dairy cows, or in any cows on a poor diet.
The disease is caused by a deficiency of glucose in the blood and in body tissues. It is important to remember that cows cannot be fed glucose in their diet, because of their complex digestive processes. Glucose is made in the rumen from suitable carbohydrates in the diet. Cows need considerably more energy during the latter part of pregnancy and in early lactation. A high producing cow may be not able to consume enough carbohydrate (particularly if the ration is pasture based only) to produce enough glucose.
If glucose demand cannot be met by additional feed of the right sort, fat is broken down in the body. If this is excessive, there is a build-up of by-products called ketones in the blood. The clinical condition - acetonaemia
- is caused by these toxic substances.
Acetonaemia has two major forms - the wasting form and the nervous form. They usually occur during the first 60 days of lactation. Cows of any age may be affected but the disease increases in prevalence to peak at the fourth calving.
Wasting form - the disease shows up as the gradual but moderate decrease in appetite and milk yield over 2-5 days. Body weight is lost rapidly, resulting in the coat having what is described as a 'woody' appearance. The dung is firm and dry but the animal is not constipated. Reluctance to move and a hangdog appearance is also seen as the syndrome progresses. A sweet smell of ketones can be smelt on the breath and sometimes in the milk. Without treatment, the milk yield falls by as much as 25% but spontaneous recovery usually occurs over about a month.
Sometimes, the disease is very mild - the only signs being a small reduction in milk production and a sweet, acetone smelling breath. Acetonaemia is sometimes seen as a secondary sign to some other more major disease disorder in the animal, for example displacement of the fourth stomach, mastitis, metritis, peritonitis, milk fever, and other conditions that result in reduction of the cows appetite for a length of time.
Nervous form - is less common but more dramatic. There is a sudden onset of signs that may last 1-2 hours. These signs include walking in circles, straddling or crossing of the legs, head-pushing, apparent blindness, aimless wandering, staggering, vigorous licking of the skin, depraved appetite, nervousness and slobbering. Affected cows may injure themselves during one of these episodes, which may occur 2 or 3 times a day. The animal is very sensitive when touched and bellows when the skin is pinched. Movement of the limbs often seems to be stiff and uncoordinated.
The aim of treatment is to restore body glucose levels as fast as possible. This can be achieved by drenching with glycerine at a rate of half a litre twice daily for two days. Ceton®
are suitable alternative commercial preparations.
It is important not to give glucose by mouth to cattle since their complex digestive system will make the acetonaemia worse.
Dextrose can be administered intravenously to give a quick initial response, and long-acting corticosteroids may be given by intra muscular injection but both these treatments are only available through a veterinarian. Where there is a lack of response to treatment, an underlying cause must be diagnosed and treated.
Prevention is always preferable to treatment and depends on adequate feeding and management.
Cows in late pregnancy must be well fed so that they calve in Body Condition Score 4.5 to 5.5 on a condition score scale of 1 - 8 where 1 is very thin and 8 is very fat. A condition score outside the range of 4.5 to 5.5 increases the cow's susceptibility to acetonaemia.
After calving, suitable high energy feed must be available. Acetonaemia is often seen in Tasmania where freshly calved cows are fed only on lush, fresh pasture. This pasture has a high moisture content and may not supply sufficient energy to satisfy the needs of high producing cows.
Supplementary feeding with grain early in lactation may be necessary to overcome any shortfall in energy.