DERMATOPHILOSIS (“RAIN SCALD”)
Dermatophilosis, also called Streptothricosis or rain scald, is a common skin infection of cattle and other large animals caused by Dermatophilus congolensis. Moist environmental conditions and long hair coats predispose to contagious infection by D. congolensis. Rain and snow that wet hair coats and cause matting present the greatest opportunity for infection. In addition to moisture and long hair, physical damage to the skin seems to be necessary because D. congolensis is thought not to be able to invade healthy skin. Depending on the region and time of year, external parasites such as flies and lice may sufficiently injure skin and also help spread the infection. Other sources of skin injury include abrasions from scratching, rubbing, or licking and moist dermatitis that develops under wet matted hair.
Heifers that are housed outside and some herds of adult cattle that have access to outdoor environments each day are most at risk for dermatophilosis.
In animals housed outdoors, a crusty dermatitis along the top line represents the classical distribution of dermatophilosis.
Animals with short hair coats may have a folliculitis with mild raised crusts and tufts of hair, whereas more classical cases with long hair coats have thick tufts of matted hair and crusts that can be plucked off to expose a thick, yellow-green pus on the skin and attachment areas of crust. Pink areas of dermis may be apparent after removal of crusted tufts of hair. Cattle that have access to farm ponds, deep mud, or lush wet pastures may develop lesions on the lower limbs and muzzle rather than the classical dorsal distribution.
Bulls may develop the lesions on the skin of the scrotum, and occasionally cows develop lesions on the udder and/or teats.
Dermatophilosis that becomes widespread or covers more than 50% of the body surface may be fatal. It is a serious cause of cattle mortality in tropical climates, where greater heat and humidity coupled with more profound insect loads exist. Death may occur in severe cases as a result of debility, discomfort, protein loss, and septicemia.
Animals with long hair coats, crusts of matted hair with underlying pus, and a dorsal distribution, especially over the gluteals, loin, and withers, are easily diagnosed by physical examination. Animals with short hair coats that have signs of folliculitis or lesions on the extremities may present a difficult differential diagnosis that includes staphylococcal folliculitis, viral infections, zinc-responsive dermatoses, dermatophytosis, and immune-mediated dermatoses.
When pus can be found underneath plucked tufts of hair or on the bottom of the detached tuft, it provides an excellent diagnostic specimen for direct microscopic examination.
Treatment is difficult and time consuming. Infections often resolve spontaneously over several weeks if affected animals can be kept dry. In addition to keeping the animals dry, it is helpful to remove tufts of crusted hair or to clip matted.
A crusted tuft of hair being removed from a cow infected with dermatophilosis. Although the underside of this tuft appears somewhat dry, more typical cases will have a thick pus evident.
Whenever possible, combining grooming with an iodine or chlorhexidine shampoo is an excellent treatment. Unlike ringworm, dermatophilosis lesions seldom are focal enough to be treated individually. Therefore overall grooming or clipping usually is necessary. Clippers, combs, and other grooming equipment must be thoroughly disinfected before reuse with chlorhexidine, iodophors, or bleach to prevent cross-contamination. The rational treatment of the disease also is complicated by the fact that in the winter animals may need as much hair as possible to survive outdoors.
Systemic therapy with penicillin or oxytetracycline is highly efficacious and can be life saving for animals with diffuse disease.
Therefore standard treatment recommendations include:
Grooming to remove crusts is very helpful
Clipping long hair, if possible
Iodine shampoos, if possible
7 days, or IM long-acting oxytetracycline dosed at 20 mg/kg once
Handlers should wear gloves and wash themselves with iodophor soaps after handling or treating affected cattle.
Babesiosis is caused by an intra-erythrocytic protozoan of the genus Babesia transmitted by hard ticks of the family Ixodidae
Unlike many other parasitic diseases, it affects adults more severely than young cattle in which infection is frequently subclinical. It causes fever, haemoglobinaemia, haemoglobinuria, anaemia and death.