The mange parasites are probably the widest spread of all the external parasites. They attack a wider range of hosts and vary more within themselves than any other. Fortunately they are host-specific in that the mange of one animal will not attack any other species.
All the domestic animals except birds but including cats, rabbits and goats are prone to attack by up to 3 or 4 types of the mange parasite. Fortunately most of them are very benign in their effect and do not cause the affected animal any serious inconvenience.
Others, however, are of major importance to us, because they can cause very serious economic loss. The most serious of all, of course, is the one which causes scab of sheep.
This disease is due to the sarcoptic mange mite and can cause immense wool damage and even death of the sheep due to the continuous scratching, biting and rubbing to allay the intense irritation.
This disease entered Australia with the first colonists and spread to every colony. It was eventually eradicated in the latter half of last century. Even today sheep from Great Britain have to be dipped as a precaution against the re-entry of the mite.
Of the larger domestic animals affected by mange the pig suffers most severely.
A mangy pig is indeed a sorry sight. The ears, hocks and base of the tail are first affected and eventually most of the body surface becomes a mass of dry scaly corrugated skin with raw areas caused by the constant rubbing.
Young pigs are the worst affected and such animals fail to grow, remain stunted and unhealthy and are prone to other infections. Older sows may have only a small area of infestation but such sows remain a source of danger to their litters and to other pigs.
Cattle show only a mild mange infection, usually over the head, tail and buttocks in spring and winter. Horses may become quite badly infected over the body and legs but fortunately the sarcoptic mange of horses is absent from Australia.
Dogs suffer from two main forms: the slowly spreading and relatively non-irritating demodectic mange which causes hairlessness and some loss of condition but not intense irritation as occurs in sarcoptic mange. The latter form leads to loss of condition and severe skin infections.
The adult mites on dogs are extremely small and can hardly be seen with the naked eye. The pregnant females burrow into the skin forming long channels in which they lay their eggs and it is this burrowing which causes most of the irritation.
The eggs hatch in a few days and the young mites reach maturity and commence egg laying within 2 weeks from the time of laying of the eggs.
Formerly treatment, usually with some oily preparation containing sulfur, was applied with moderate success. Today the newer insecticides have provided an easy, non messy almost 100 percent effective treatment, and usually one dressing is sufficient.