Hairy Warts (Digital Dermatitis)
click on images for detail

Description

The disease usually affects the skin above and between the bulbs of the heels (See Anatomy).

The lesion will encroach on the horn of the heel.

Infrequently, the lesion will be found around the false digits (dew claws). Initially, the lesion may appear similar in appearance to interdigital dermatitis.

The photograph on the right is typical of a relatively early digital dermatitis lesion. (click image)

The central circular area of granulating tissue is surrounded by a "halo." Photograph right below.

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As the lesion ages, it may start to get more and more "hairy." Photograph above left.

The lesion on the foot in the picture right is usually termed an "erosive lesion." The skin has been completely lost and the causal organisms appear to be attacking the horn of the heel. (click image)

Lesions of this type may appear separately from those described above or in combination with them.

Cause

It is believed that two or more microorganisms working together cause the condition known as "papillomatous digital dermatitis" or hairy warts. Research has shown that for the infection to gain a hold the feet must be subjected to prolonged exposure to moisture and exclusion to air. The predominant organisms (spirochetes) will induce an immune response in an affected animal but, to date, an effective vaccine is not available.

Treatment and Control

No single specific treatment can offer a guaranteed cure. Herds respond differently to different modes of treatment and control. It is, therefore, suggested that measures shall be combined and changed frequently in the hope that an ideal combination will be encountered.

Foot Baths

Whatever form of foot bath is used, it is highly desirable that the feet should be cleansed prior to exposure to any chemical or antibiotic solution. A cleansing foot bath, followed by a treatment footbath is the best solution.

Oxytetracycline 5-6g/ litre or Lincospectin 150g in 200 litres of water has been found effective. The treatment should be given every three or four weeks. The antibiotic should be changed every four months.

In order to conserve antibiotic, a minimal fluid foot bath or a "hoof mat" may be used (see Foot Bathes).

Chemical solutions have, so far, not proven to be effective against this disease except as a supplementary treatment. Some workers alternate an antibiotic solution with a 7% solution of copper sulfate or a 5% solution of formalin.

Topical Dressings

The worst affected feet require the animal to be restrained, the foot cleansed, and a topical antibiotic applied in powder form. The powder is held in place with a bandage. Recently, an inexpensive device "Bovine Booties" has been introduced. This is a durable, waterproof "diaper" which holds a dressing between the heels while staying fixed by velcro straps around the pastern.

Hygiene

This disease is more prevalent if the feet are continually exposed to slurry. The risk of infection is also relative to the number of organisms present in the slurry.

Although it is very difficult to reproduce this disease artificially, it is wise to see that instruments used on feet are disinfected prior to use.

Immunity

Heifers have no immunity to this disease. Animals introduced to a herd must be isolated for a month prior to being introduced to the main herd. At this time no vaccine has been proven reliable.