by

Geoff and Christine Smith

The subject of cataract formation has been an integral part of marsupial management for some years.

Much confusion abounds in relation to diets. The subject of carbohydrate metabolism is a large and intricate subject.    Hopefully, in the near future veterinary research will shed more light on this most interesting subject.

Some researchers found that cataract formation was due solely to a genetic deficiency of two enzymes in marsupials causing Galactosemia, as a result of high levels of lactose in cow’s milk.    Lactose is converted to Galactose causing an accumulation of Galactose which ultimately is converted in the lens to sugar alcohol, the osmotic effect causing Bi-lateral cataracts.

A number of low Lactose diets were recommended.   In my view, these diets resulted in the deaths of many thousands of young animals through malnutrition. Obviously high levels of lactose appear to be the culprit, however, I believe the mechanics of its conversion to cataracts is not fully understood.

A number of other factors need to be considered. Over the last few years considerably improved management information has been available and the introduction of adequate feeding tests has solved many problems.

In earlier years, by far the majority of young marsupials were suffering the effects of starvation resulting in malnutrition, prolonged dehydration, mismanagement and stress related problems causing considerable hyperactivity of the endocrine system and imbalance of hormonal output.

All the above problems have a profound impact on carbohydrate metabolism.

Cataract formation in marsupials is not exclusively a problem of very young animals.    I have observed cataract formation in grey kangaroos and wallaroos as old as 15 to 18 months.    Investigating their history, it was found they were usually suffering the effect of malnutrition, dehydration and stress related problems.   Obviously a small percentage is genetically predisposed to cataracts.    We have raised hundreds of young marsupials and not been able to produce cataracts in even the very young.