Mange is a collective name for allergic dermatitis caused by ectoparasitic infestation by mites that are obligate parasites and spread from animal to animal by direct contact. Mange usually appears as a skin condition associated with irritation and scratching that leads to inflammation, exudation and crusts and scabs forming on the skin. Untreated mange leads to thickening of the skin and loss of condition of the animal. The disease is often seen in animals in generally poor condition and during the winter season. The condition sometimes causes welfare problems in dairy herds as the treatment of lactating animals is not carried out due to long withdrawal periods required in connection with the efficacious treatments.
The mange mites prevalent in the UK can be divided into burrowing and non-burrowing mites. The only burrowing mite of importance in the UK, Sarcoptes scabiei, has a life cycle of about three weeks from egg to adult, after which the adult female will lay eggs for up to 60 days. The most common sites for sarcoptic mange on cattle are inner thigh, underside of neck and brisket and around the root of the tail. Small areas of infestation do not cause major irritation to the animal, but a generalised condition can be extremely distressing.
The non-burrowing mites, Chorioptes and Psoroptes, have a similar life-cycle to the burrowing mites, with a slightly shorter adult phase of 40 days. The predilection site for Chorioptic mites is at the base of the tail, in the perineum and at the back of the udder in the winter. Long-haired, highland cattle are considered to be particularly susceptible to infection. Psoroptic mites are initially found on the withers, with the condition rapidly worsening to exudative dermatitis, associated with severe irritation.
The prevalence of mange in cattle in the UK is considered to be at a low level. A summary of surveys suggests that the prevalence in dairy herds ranges from 1-10% and in beef herds from 1-50%. Whilst dairy cattle are generally less susceptible than beef animals, all cattle are less susceptible to mange than sheep, as grooming is more efficient in cattle and acquired infections are usually eliminated by the animal.
Mange in Cattle
Mange is the term used to describe infection by mites, microscopic relatives of spiders. They inhabit and damage the skin of domestic animals and man. Problems are most frequently seen in the autumn and winter but can occur all year round. There are three main species of mite that affect cattle in the UK, the surface mite (Chorioptes bovis), the burrowing mite (Sarcoptes scabiei) and the sheep scab mite (Psoroptes ovis) The surface mite is the most commonly seen in the UK
The effect of mites
The surface mite is usually found on the neck, legs, and tail head. It produces limited hair loss, which only increases slowly in size. However, the lesions are obviously itchy which results in hide damage elsewhere as the cattle try to rub the affected areas.
The sheep scab mite is found on the flanks and around the tail head and anus. Although this mite feeds on the surface of the skin, its mouthparts pierce the skin, producing blisters, which are very irritant.
The burrowing mite prefers the neck and the loin area next to the tail (leading to the description of ‘neck and tail’ mange). As they burrow into and out of the skin they produce a much more intense irritant reaction so that the skin damage rapidly develops with much larger areas being affected and the skin becoming very thickened and crusty. Infection of the damaged areas often develops and affected animals have much reduced production
Life cycle
The surface mite and the sheep scab mite both spend their entire life cycle on the surface of the skin. Females lay around 90 eggs which once hatched take around ten days to develop into mature adults.
The burrowing mites lifecycle is more complex. The female mite tunnels into the skin, and lays around 50 eggs. These hatch in four or five days, each releasing a larva. Some of these tunnel to the surface to become adult others develop in the tunnels; this process takes around two weeks. More tunnels are often formed during the mating process.
For all three species, infection is spread mainly by direct contact between cattle. However, the burrowing mite can survive for some time off the host, so, for this species, bedding and objects that come into contact with infected animals may become contaminated and help spread the infection. For the sheep scab mite, although mites found on cattle are very similar to those found on sheep, it is very unlikely that natural spread from cow to sheep (and vice-versa) occurs.
Diagnosis
Areas of thickened skin in obviously itchy animals are very suggestive of mites, particularly if there is no evidence of lice. To confirm a diagnosis get your vet to take a skin scraping for examination under a microscope.
Treatment
A range of products is available to treat mange in cattle. The choice is between pour-on products and injections. The first are easier and quicker to use and are often cheaper. However, in severely infected animals (as is often seen in burrowing mite problems), the skin reaction can mean that contact between the product and the mite is limited. In such cases, scabs may have to be removed before treatment. If very severe then injectable products are probably a better bet. For very severe surface mite problems, an injection should be followed up by a pour-on treatment when the skin has recovered, as in this species (unlike the burrowing mite) injections only control but do not eliminate. Sheep scab mite can be effectively controlled with injections
The timing and frequency of treatments depend very much on individual circumstances. In most clinical cases, two treatments will give adequate control of cattle mites for the housing period. Whichever product you use, dose accurately, ensuring that you do not under-dose as under-dosing is the best way of ensuring the development of mites that are resistant to treatment.
Treat all cattle on the property at the same time if possible, choosing a time when they are not stressed or in poor condition. If groups have to be treated separately, such groups should be kept apart to ensure there is no contact between treated and untreated groups.