Skin Disease

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ringworm | warts | dermatophilosis | photosensitization 

Introduction: There are four major types of skin diseases that are common to cattle. The cause, clinical signs, diagnosis, and treatment for each one of these problems will be discussed below.

  1. Ringworm (Dermatophytosis)

Cause: Ringworm in cattle is a fungal infection of the skin caused most commonly by the organism Trichophyton verrucosum.

Clinical Signs: Ringworm causes hair loss and crusts to form on the skin. There is usually more than one lesion present and the lesions can form almost anywhere. However, the head and around the eyes or neck seem to be the most common areas that are involved.

Disease Transmission: This skin problem is spread from animal to animal by direct contact. It can also be spread from animal to animal when contact is made with a contaminated object (equipment, trough, feeder, etc.). Young animals and cows that are sick, exposed to damp environments, or have poor nutrition are at an increased risk of developing the disease. Animals that are kept indoors or away from adequate sunlight are also at risk.

Diagnosis: The best way to diagnose this problem is by performing a fungal culture. This is accomplished by taking hair samples from the outside edge of a few of the lesions. The hair is then placed on fungal specific media and any dermatophytes are allowed to grow.

Treatment (choose one of the following):

* Allow the animal as much exposure to sunlight as possible.

  1. Warts (Papillomatosis)

Cause: Warts are caused by a group of viruses, called bovine papilloma virus (BPV1-6).

Clinical Signs: Warts can be found on the head, neck, teats, ears, and penis. The lesions are white to grey, firm and raised. These lesions are harmless in almost all situations, except where mastitis or pain is involved. These warts are most common in animals under 2 years old.

Disease Transmission: Warts are spread by direct contact from animal to animal. They can also be spread when contaminated equipment such as dehorning, ear tagging, or tattooing instruments are not cleaned properly between animals.

Treatment: Small warts can be crushed, pinched off, frozen (cryosurgery), or surgically removed. In severe cases or when a herd-wide wart problem exists, a specialized vaccine can be designed that helps prevent further spread of the wart. This vaccine is made from wart samples collected right from the herd or animal. This is called an "autogenous" vaccine and is specific for the virus that is causing the wart problem in the herd or individual animal.

Prevention: When an animal has a wart infection, it should be isolated from other animals. Any infected animal should also be kept from rubbing on feeders and posts that may be used by other animals. Cleaning of dehorning, tagging, and tattooing equipment with a product like chlorhexidine is essential for preventing the spread of warts. There are vaccines available that can be helpful in some herds as long as the strain of the virus in the herd matches the one in the vaccine. See page C965 for vaccine information.

  1. Dermatophilosis (Rain scald, streptotrichosis)

Cause/Clinical Signs: Dermatophilosis is caused by the actinomycete Dermatophilus congolensis. This problem causes areas of hair loss, matting, crusting, and scab formation over the back areas. Small tufts of hair can easily be removed, exposing a raw, sometimes infected lesion.

Disease Transmission: Like warts, this problem is spread by direct contact from animal to animal. It can also be spread when contaminated equipment is not cleaned properly between animals. Insects may also spread the disease from animal to animal. Wet, humid, rainy environments and any situation that causes the surface of the skin to be damaged, increase the chances of developing the problem.

Diagnosis: A diagnosis can often be made based on the appearance of the lesions. If this is not possible, a culture or microscopic examination is required.

Treatment: For effective treatment, four things should be done:

Prevention: Isolating any diseased animals and controlling biting insects are two of the most common preventative measures.

  1. Photosensitization - This topic is discussed in detail on F835

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