Dear Mohair producer

Most Mohair farmers are unaware of Dermatophilus congolensis (a bacteria) but have seen evidence of its presence on their Angora goats over many years and one of the reasons Zinc sulphate was historically added to the dip.

A crusty tan brown colour on the skin surface can be seen when infected goats are carefully inspected. In most cases it appears to be insignificant but over the last two years many producers have reported concerns to the SAMGA Vet.

These included:

• Crusty skin lesions (often on the ears) or body (photo below)
• The hair ‘breaks’ (pulls away from the skin) easily and bald patches can develop.

The angoras have lost patches of hair or in severe cases become bald.

• Crusty lesions developed on the skin 

• The goats seem to become itchy after dipping.
• Thicken crusted lesions ‘sores’ on the skin reported (often legs) which when scrubbed clean the skin appears red and inflamed (below)

Due to these reports SAMGA have over the last 2 years tested samples from 7 of these farms. They all tested positive (on culture) for Dermatophilus congolensis.

What other signs (apart from those reported above) can be seen and how does it affect the goat?

The goat is not always itchy. Most goats recover spontaneously within 3 weeks of the initial infection.  These infections usually have little effect on general health.  

 What is Dermatophilus congolensis?

To put it simply it is a type of bacteria or for those who really want to know it is actinomycete. It has 2 forms (i) filamentous hyphae  and (ii)motile zoospores.

This is the same bacteria that causes ‘klont-wol’ in sheep.

How does Dermatophilus develop and what causes the hair loss?

To establish infection, the infective zoospores must reach a skin site where the normal protective barriers are reduced. Wetting of the skin causes disruption of the sebaceous film on the skin rendering the skin susceptible to infection. Zoospores germinate to produce hyphae and the branching filaments invade the living cells of the epidermis of the skin and the sheaths of the hair follicles. The organism causes inflammation and exudate resulting in the crusty skin associated with the hair loss.  

How is Dermatophilus transmitted?

• Contact can occur between goats especially when wet after dipping. The reason is that the zoospores occur in the crusty scabs which when wet are released. Wetting in addition to the activation of the zoospores may also transport the spores to other non-infected sites on the goat or to other goats.
• Contact with contaminated plants or insects or soil.
• Outbreaks of hair loss often occur after dipping, shearing, periods of rain or ear punching.
• Continuous wetting of the feet, the face and fleece when grazing wet pastures may play a contributing role and why lesions are often seen on ear margins.
• Some goats may have crusty lesions remaining on ear margins and these goats may act as carriers.
• Dermatophilus can survive in contaminated soil for up to 4 months
• Any damage to the skin may predispose it to infection.

Dermatophilus can be transmitted to people. Thorough handwashing with an antibacterial soap is recommended after contact with an infected animal.

Treatment:

• Zinc sulphate solution 5% (dip/spray lesions)
• Antibiotic injections of Long Acting Tetracycline or Penstrep . Organisms are susceptible to a wide range of antimicrobials: erythromycin, spiramycin, penicillin G, ampicillin, chloramphenicol, streptomycin, amoxicillin and tetracyclines.
• Bathing of crusts with topical disinfectant.

Two doses of long-acting oxytetracycline (20 mg/kg)2-3 days apart have shown to be curative in 100% of sheep, compared with cure rates of 80% in sheep for a single dose.

Prevention:

• Preventative treatment by adding Zinc sulphate to the dip. (0.2-0.5%)
• Isolating clinically affected animals,
• Culling affected animals,
• Controlling ecto-parasites
• Avoid excessive dipping.
• Zinc levels should be checked because outbreaks have been associated with zinc deficiencies.

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