Mites in Cattle

Introduction

Mite infestation (mange) in cattle can be caused by several different species and result in a variety of signs from mild and insignificant scurf and scaling to severe crusting skin lesions, discomfort and secondary complications. Outcome is dependent on both the species of mite and the health and management of the cattle and their individual responses to infestation. Mange can be very difficult to treat and a veterinary diagnosis should be sought for severe or unusual skin problems.

Cause

The most common mite found on UK cattle is Chorioptes bovis which causes chorioptic mange typically seen on the hind legs, udder and tail base. These mites live and reproduce near to the skin surface, feeding on skin secretions and debris. Chorioptic mites are able to survive off their host for at least 3 weeks under suitable conditions, and are also capable of infesting other domestic species including sheep, goats and horses.

Mange caused by Sarcoptes scabiei (scabies mites) is less common but appears to be increasing in the UK. Sarcoptic mange lesions are typically located on the neck, head and tail base. Sarcoptic mites tend to burrow and live deeper in the skin than chorioptic and psoroptic mites. Infestations are often mild, but can result in severe disease. These mites are usually adapted to live on a single host species, but some may be able to spread particularly from goats and pigs.

There have previously been reports in the UK of a cattle-adapted strain of the sheep scab mite, Psoroptes ovis. Whilst neither sheep or cattle are thought to play important roles in the spread of each other’s host-adapted strains, this relationship is not fully understood and caution should be exercised where psoroptic mange occurs in either species. Psoroptic mites can cause severe disease and widespread outbreaks if introduced into a herd. Beef cattle appear to be more commonly affected, although it has been reported in dairy herds, and outbreaks associated with importation of carrier animals from abroad. Psoroptic mange is typically observed on the back, shoulders and tail. Like Chorioptes, psoroptic mites are also able to survive in the environment for a limited time of around 18 days.

Welfare and Economics

Mild mite infestations with few or no clinical signs are generally well tolerated and not considered significant. Severe cases may result in intense itching due to the presence of mites and their faeces and the resulting immune response leading to intense itching and skin damage, with crusting and oozing of serum from the damaged surface and the potential of secondary infections. Severe outbreaks may be associated with loss in productivity through reduced weight gain, and milk yield in dairy cattle. Mites infestation can be present year-round, but are of particular concern over winter in housed animals. Signs may appear to resolve spontaneously over the spring and summer months, although animals may continue to carry low levels of infestation allowing signs to recur once favourable conditions return. Imported cases of the less common mites can be very costly and require large scale, repeated treatment and isolation of groups of animals.

Clinical Signs and diagnosis

Skin lesions associated with chorioptic mange are usually mild and spread slowly, located on the tail head, legs, feet and udder with dry, scaly skin and localised hair loss. In bulls, the scrotum may be affected. Lesions are usually only moderately itchy, but cows may bite or rub the affected areas. Animals in poor condition or with other underlying disease can develop severe crusting and secondary infections.

Figure 1. Mange at the trailhead of a dairy cow causing scaling, itching and hair loss.

Figure 2. Mange in the scrotum skin of this bull was causing crusting, itchy skin.

Sarcoptic mange tends to cause hair loss and crusting and intense itching around the face and neck and sometimes the tail head, although more widespread lesions can be seen in some animals where severe disease develops.

Psoroptic mange in cattle can be severe with extensive crusting lesions along the back and shoulders with intense itching.

Diagnosis of mange is typically based on clinical signs, location of lesions, time of year and conditions present. However, if disease is severe and/or complicated veterinary advice should be sought as further diagnosis may be required to detect mites and/or to investigate the possibility of other skin conditions. Unlike lice, mites cannot be seen with the naked eye. Microscopic examination of skin scrapes taken from the edges of affected areas allows the detection of mites, and identification of the type of mite present.

Figure 3. Severe crusting lesions caused by psoroptic mange in a bull

Prevention

Preventing entry of any mange into a herd through isolation and quarantine is the best course of action where it is not already present on farm. This is of particular importance for the rarer, more severe mange mites, particularly Psoroptic mange for which treatment and eradication can be extremely problematic. This should form part of the herd health plan and be followed for all incoming stock. Seek veterinary advice to diagnose skin lesions in any quarantined stock and treat as recommended.

Herds with persistent or repeat problems of severe chorioptic mange should seek advice to determine underlying causes of poor nutrition or health which may be contributing to the susceptibility of the cattle.

It is also advisable to avoid introducing unaffected animals into areas where previously infested cattle have been kept for up to 3 weeks since it is known that mites can survive in the environment for extended periods of time.

Treatment

Treatment of mild cases of chorioptic mange is usually unnecessary, although as with lice some group 3-ML products used to treat roundworms at housing can have the added benefit of reducing mite burdens also. Severe cases of chorioptic and sarcoptic mange can be treated with pour-on preparations of permethrin and group 3-MLs (ivermectin, eprinomectin, moxidectin and doramectin). Some injectable group 3-ML preparations may be used, but are less effective for these mites. It is important to check the datasheet of products for licence of efficacy, and it should be noted that products stating “aids in control” for named parasites