Hair loss in Angora goats- Dermatophilosis (Dermatophilus congolensis )

Monday, 9th May 2016

Dr Mackie Hobson (SAMGA Vet)

A number of farms have reported Angora goats with significant hair loss. A crusty tan brown colour on the skin surface can be seen and when the hair is pulled it easily ‘breaks’- pulls away  at the skin surface.

In cases where importantly red and blue lice have been ruled out we have done cultures to determine the cause of this hair loss.

  • On 4 farms where this hair loss has occurred in Angora goats we took hair pluck and skin scraping samples. These were examined and cultured.
  • All 4 cultured positive for Dermatophilus congolensis.

 

Dermatophilus congolensis is seen more in sheep where it causes ‘klont-wol’ .

In goats it is often associated with wet hair from dipping. Hence one of the reasons farmers in the past added Zinc Sulphate to dip tanks.

The infection is often seen as crusting lesions on the ear margins of goats.

Transmission

  • Contact between goats especially when wet such as after rain or dipping.
  • Contact with contaminated plants or insects.
  • Prolonged wetting of the skin causes disruption of the sebaceous film on the skin rendering the skin susceptible to infection by dermatophilosis.
  • The zoospores occur mainly in the crusty scabs which when wet are released. The number of viable zoospores decreases as the scabs dry. Hence these outbreaks of hair loss often occur after periods of rain, dipping, shearing or ear punching.
  • Continuous wetting of the feet, the face and fleece when grazing wet pastures may play a contributing role.
  • Wetting in addition to the activation of the zoospores may also transport the spores to other non-infected sites on the goat.
  • Some goats may have crusty lesions remaining on ear margins and these goats may act as carriers.
  • Dermatophilosis can survive in contaminated soil for up to 4 months
  • Any damage to the skin may predispose it to infection.

What is Dermatophilus congolensis?

D congolensis is a gram-positive, non-acid-fast, facultative anaerobic actinomycete.

It has two characteristic morphologic forms: filamentous hyphae and motile zoospores. The hyphae are characterized by branching filaments (1–5 μm in diameter) that ultimately fragment by both transverse and longitudinal septation into packets of coccoid cells. The coccoid cells mature into flagellated ovoid zoospores (0.6–1 μm in diameter).

 

How does Dermatophilosis develop?

To establish infection, the infective zoospores must reach a skin site where the normal protective barriers are reduced or deficient. Zoospores germinate to produce hyphae, which penetrate into the living epidermis and subsequently spread in all directions from the initial focus. Hyphal penetration causes an acute inflammatory reaction. Natural resistance to the acute infection is due to phagocytosis of the infective zoospores, but once infection is established, there is little or no immunity.

What causes the hair loss and crusty lesions?

The branching filaments of the dermatophilus invade the living cells of the epidermis of the skin and the sheaths of the hair follicles where extensive proliferation of the organism occurs causing hair loss. The organism causes inflammation and exudate resulting in the crusty skin associated with the hair loss.

Clinical signs

Angora goats.

  • Angora goats the infection is usually associated with hair loss
  • Crusting lesions against the skin can be seen. Flecks of yellowish- white to brownish grease or crusts.
  • Reddening (erythema ) of the skin

Angora goat skin with hair loss and exudate cultured positive for Dermatophilus congolensis

The goat is not always itchy. Most affected animals recover spontaneously within 3 weeks of the initial infection.  In general, the onset of dry weather speeds healing.  These infections usually have little effect on general health.  Animals with severe generalized infections often lose condition

Clinical signs are well documented in sheep:

Acute lesions:  erythema, exudation and flecks of yellowish –white to brownish grease or crusts. In severe cases large amounts of exudate and scabs are formed. The sticky exudate can dry and glue staples together and hence the name ‘klont- wol’ in sheep.

Chronic lesions:  in sheep are seen as lumps 30-40mm in diameter.

The bacteria can cause strawberry footrot

Diagnosis

  • Clinical appearance
  • Smears, skin scraping
  • Biopsy
  • Culture

Treatment:

  • Bathing of crusts with warm water, topical disinfectant (eg. chlorhexidine).
  • Antibiotics injection of LA tetracycline or penicillin + streptomycin
  • Zinc sulphate solution 5% (dip/spray lesions)
  • Preventative treatment by adding Zinc sulphate to dip. (0.2-0.5%) with Alum crystals (1%)

Organisms are susceptible to a wide range of antimicrobials: erythromycin, spiramycin, penicillin G, ampicillin, chloramphenicol, streptomycin, amoxicillin, tetracyclines, and novobiocin.

Two doses of long-acting oxytetracycline (20 mg/kg) 1 day apart have shown to be curative in 100% of sheep, compared with cure rates of  80% in sheep for a single dose.

  • Isolating clinically affected animals,
  • culling affected animals,
  • controlling ecto-parasites
  • Keeping the goats dry is important.
  • Zinc levels should be checked  because outbreaks have been associated with zinc deficiencies.

Farmers beware:  Zoonotic Risk

Dermatophilosis can be transmitted to people. Direct contact with an infected animal can lead to infections on the hands and arms. Affected animals should be handled with gloves, and thorough handwashing with an antibacterial soap is recommended after contact with an infected animal.

 

Reference:

Kleinvee-siektes:  De Wet and Bath

Infectious diseases of livestock : Coetzer, Thomson, Tustin

The Merck Veterinary manual

 

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