Skin Diseases By William C. Rebhun 1^^ ingworm is a fungal in- Mfection of the skin (dermatomycosis) that occurs commonly in calves and occasionally in adult cattle. It is contagious; therefore, when one calf in a group develops the problem, many calves usually are affected. The causative agent generally is Trichophyton verrucosum, a fungus that lives on the skin of cattle and other livestock. The signs of ringworm are hair loss and development of heavy gray-white crusts at the site of infection. The lesions do not cause itching. If the crusts are scraped or cleared away, a raw area of skin devoid of hair is found. The lesions are roughly circular and usually 1 to 10 centimeters in diameter. William C. Rebhun is Associate Professor of Veterinary Medicine and Ophthalmology, New York State College of Veterinary Medicine, Cornell University, Ithaca. Calves commonly are affected in several spots around the face, eyelids, ears, and neck, although lesions can occur anywhere on the body. Adult cattle, when affected, tend to have more generalized lesions on the face, neck, trunk, and tail region. Spread of ringworm occurs through body contact and inanimate objects such as brushes or blankets used on an infected animal and then used on other animals. This problem can be transmitted to humans very easily and is an important public health problem for farm workers and veterinarians that handle affected animals. If ringworm is suspected in a human who has been in contact with cattle, a physician should be contacted for appropriate treatment. Treatment is difficult because of the multiple sites and large number of animals that tend to be affected. For an in- Skin Diseases 161
Cornell University Ringworm is a fungal infection of skin that causes circular areas of hair loss and crusting of the infected skin. dividual animal, the crusts can be carefully removed and topical applications of iodine, chlorox, captan, or thiabendazole applied. For widespread lesions or multiple animal problems, captan sprays, oral griseofulvin, or other preparations may be used. It is best to consult with a veterinarian if the problem is widespread. Fortunately, the disease tends to be self-limiting, and affected animals usually recover spontaneously within several months. Vitamins A and D sometimes are administered as empiric treatment. and sunlight is felt to be helpful in resolving the problem. Because of the risk of contagion, affected animals usually are not allowed to be shown in cattle shows. Warts And Calves Warts, or fibropapillomas, are benign skin tumors that tend to occur in calves between 4 to 24 months of age. The tumors are caused by infection of the skin with the bovine papilloma virus. These are contagious through direct contact especially at sites of skin abrasion or injury. The virus also can 162 Dairy and Beef Cattle
be inoculated into the skin by dehorners, castration devices, and eartags which have been contaminated by affected animals. Usual signs include raised growths that have a gray appearance and are covered by a crust. Warts usually are 1 to 10 centimeters in diameter. A calf rarely will develop "atypical warts," which are large, very numerous, and tend to affect large areas of the body. Warts tend to occur on the face, head, eyelids, ear, neck, and topline. These warts are not contagious to people and tend to resolve spontaneously over a course of several months in affected calves and heifers. There is no specific treatment, but large warts can be removed surgically. Wart bacterins or vaccines are used sometimes in an attempt to prevent the disease or speed resolution of the problem, but the results are variable. These vaccines should be discussed with a veterinarian if a high incidence of warts exists on a farm. Again, as in ringworm, the contagious nature of this problem may preclude moving affected animals to shows. Mange Problems Cattle mange is caused by mange mites of four major types. In general, mange causes loss of hair and tremendous itching due to movement of these tiny parasites within the skin layers. Chorioptic mange or "tail mange" is probably the most commonly recognized clinical problem and causes loss of hair over the tailhead, escutcheon, and rear udder attachment, itchiness, skin crustiness, treading of the feet, and decreased production due to the irritating nature of the disorder. This parasite also may affect horses, sheep and goats, although the signs are somewhat different than those seen in cattle. Sarcoptic mange, or barn itch, causes a severe, generalized loss of hair, reddening of the skin, and profound itching. Affected animals lose condition dramatically and decrease in production due to the irritation and itching caused by the parasites. The parasite can affect other species of livestock, such as horses, sheep, pigs, and goats, as well as people. Psoroptic mange causes an itchy, crusty dermatitis on the neck, withers, and tailhead of affected cattle. The dermatitis can become generalized in some instances. This type mange tends to be spe- Skin Diseases 163
Murray Lemmon. USDA This barbed wire fence became a scratching post for cattle so severely bothered by scabies mites that they rubbed their hides raw to try and relieve the itching. Signs like these are signals that parasites such as scabies mites or sarcoptic mange may be affecting a herd. cies specific and, therefore, the cattle psoroptic mange mite does not usually spread to other species. Demodectic mange tends to be the most innocuous of the manges affecting cattle, and it consists of nodules or pustules on the neck, shoulders, and trunk of affected cattle. It does not tend to cause itching and is of concern mainly because of possible damage to the hide of affected animals. Demodectic mange tends to be species specific, and cattle do not spread this problem to other livestock species. 164 Diagnosis of mange requires a veterinarian to do skin scrapings or a skin biopsy and identify these specific parasites under a microscope. Whenever mange is suspected or diagnosed, a vetterinarian should be notified for recommendations. In cases of psoroptic or sarcoptic mange. State or Federal officials may need to be notified to enact treatment and control procedures. These include quarantine and chemical dips or sprays to kill the mange mites on all animals. The diseases are highly contagious to all animals within a Dairy and Beef Cattle
Murray Lemmon. USDA herd and early recognition is necessary to allow successful therapy. Demodectic mange seldom requires treatment in cattle, and chorioptic mange usually is managed by specific sprays containing lime sulfur or ciodrin. Murray Lemmon, USDA When severe loss of hair, reddening of the skin and profound itching is noticed in a herd, diagnosis requires a veterinarian to do skin scrapings or skin biopsy to identify the specific parasite so that correct treatment can be performed. Louse Infestation Both biting and sucking types of lice infest cattle. Louse infestation tends to be more of a problem during colder months when cattle have longer coats and are confined in close proximity to one another. Lice are species specific for the most part and cattle lice tend not to affect other species of animals or humans. The major signs are itching and loss of hair in affected calves and cattle. Hair loss is Skin Diseases 165
self-induced due to rubbing and licking by affected animals who are greatly irritated by the lice. In severe cases, blood-loss anemia may develop due to thousands of lice draining blood from a single animal. This most often occurs in younger animals that are exposed to large numbers of lice. Many effective insecticides are available to control lice. These can be applied as powders, sprays, pour-ons, or dust bags. In any event, precautions should be taken to be sure the insecticide used is approved and safe for the breed, sex, age, and function of animal to be treated. Streptothricosis Streptothricosis, or Dermatophilosis, is a disease caused by Dermatophilus congolensis, a microbe that grows best in moist areas. In cattle, infection of the skin tends to occur when the hair coat is long. Conditions that favor long hair coats, wet hair coats, matting of the hair, or skin abrasions favor growth of the organism. The skin lesions consist of crusts and clumps of hair that can be plucked off, leaving a raw area of dermatitis covered with a purulent discharge. The majority of lesions oc- I cur on the topline of affected cattle, but in severe cases lesions can be generalized and affect the legs, udder, and trunk. The organism is spread by contact, and other species such as sheep and horses can be affected as well as people. Treatment necessitates grooming and clipping of hair if the hair coat is excessively long or moist. Grooming will remove the tufts and clumps of hair to reveal the raw skin lesions which then can be treated with iodine shampoos. In severe cases, systemic penicillin and streptomycin may be needed to help destroy the organisms. Warbles or back grubs. This important parasite of cattle is responsible for tremendous economic loss in the form of damaged hides from affected cattle. The adult parasite is a large fly, Hypoderma bovis or H, lineata, that deposits its eggs on the hair of cattle during the fly season. These eggs hatch, the larvae migrate through the skin of the host cow and through several other tissue layers until they reach the subcutaneous tissue on the back. At this point, they establish air holes in the skin and remain under the skin until mature, at which time they emerge 166 Dairy and Beef Cattle
Many effective insecticides are available for treating parasites. Remember it is extremely important to read the label. Safe and effective use depends upon many variables, including sex, breed, age and function of the animal as well as time of the year. Murray Lemmon, USDA Mane T. Sebrechls USDA-APHiS and drop to the ground. They then mature into adult flies and complete the life cycle. Younger animals tend to be more severely affected than older cows. Insecticides are available to kill these larvae before they complete their migration. However, it is extremely important to treat according to directions since treating at the wrong time of the year can lead to severe reactions. Each geographic area has its own specific time of treatment, and treatment to prevent grubs should be discussed with a veterinarian. Skin Diseases 167