Miscellaneous Conditions
Dermatologists in referral hospitals see a disproportionate number of goats with “uncommon” skin diseases that have not responded to empirical treatments, including antibiotics, parasiticides, and manipulations of the diet.
Extensive diagnostic workup has characterized and identified the cause of some of these conditions, but others remain perplexing. In particular, crusting lesions of Nubian goats, especially involving the ears and face, have frequently defied attempts to identify an etiology or an effective treatment.Pemphigus
Pemphigus foliaceus is an autoimmune disease in which the affected individual (human, dog, cat, horse, or goat) develops auto-antibodies against the glycocalyx of keratino- cytes. Reports of the condition in goats are few (Jackson et al. 1984; Scott et al. 1984; Valdez et al. 1995; Pappalardo et al. 2002; Cornish and Highland 2010; Janzen et al. 2011). There is no evidence that the condition is hereditary.
Clinical Signs and Diagnosis
Clinical findings include vesicles or blisters, pustules, crusts, alopecia, and sometimes pruritus. The lesions may be generalized over the entire body or may be concentrated in or begin in a more restricted location, such as the perineal region, ventral abdomen, and groin (Jackson et al. 1984). Diagnosis requires full-thickness skin biopsies of lesions containing intact vesicles or pustules. Routine histology (formalin fixation) reveals intraepidermal acantholysis with formation of clefts, vesicles, or pustules. Cells of the stratum granulosum may be seen attached to the overlying stratum corneum (Scott 1988). These granular “clingons” may also be found in direct smears of intact vesicles, along with nondegenerate neutrophils and/or eosinophils (Scott 2018), but are not pathognomonic, at least in other species (Olivry 2006). Direct immunofluorescence testing (tissue in Michel’s fixative; no glucocorticoids administered in the past three weeks) reveals intercellular deposition of immunoglobulin.
Serologic testing (indirect immunofluorescence) is unreliable for the diagnosis of caprine pemphigus (Scott et al. 1987).Treatment
Treatment of pemphigus may be attempted with high doses of systemic glucocorticoids (1 mg/kg prednisone or prednisolone intramuscularly (IM) twice daily for 7-10 days, then alternate-morning therapy at reduced dosage). A long- acting corticosteroid injection (dexamethasone-21- isonicotinate 0.04 mg/kg IM) once every two months suppressed clinical signs in one goat (Pappalardo et al. 2002), but the potential risks are greater. Another goat responded well to prednisolone injections followed by methylprednisolone acetate, eventually recovering completely (Janzen et al. 2011). Oral prednisolone is not generally used because of very low bioavailability in ruminants (Koritz 1982), but has been reported to be effective (Corke and Matthews 2018). In young or non-responsive goats (Cornish and Highland 2010), chrysotherapy with aurothioglucose (1 mg/kg weekly until response is observed, then monthly) may be tried. This drug has been discontinued in the United States. Although adverse reactions to gold have not been reported in goats, hemograms and urinalyses should be monitored. Gold treatment was successful in two reported cases (Scott et al. 1984; Cornish and Highland 2010) and unsuccessful in another (Valdez et al. 1995).
Alopecia Areata
Solitary or multiple annular areas of alopecia on the face and neck have been reported in otherwise healthy goats (Scott 2018). An immune-mediated attack on anagen hair follicle bulbs is the proposed etiology.
Alopecic Exfoliative Dermatitis, Psoriasiform Dermatitis
A non-pruritic, seborrheic skin condition affecting Pygmy goats of all ages has been described in England. Hair loss, scaling, and crusting occur around the eyes, lips, chin, ears, ventrum, and perineum. Histology reveals a psoriasiform dermatitis, and the condition responds to steroids but recurs when treatment is stopped (Jefferies et al. 1987, 1991). There is orthokeratotic and parakeratotic hyperkeratosis (Scott 2018). A very similar condition has been studied in Pygmy goats in the Netherlands (Kuiper 1989). The condition was not contagious and did not respond to administration of corticosteroids, zinc, vitamin A, or selenium. A hereditary basis was suspected.
There is a single report of exfoliative dermatitis as a paraneoplastic syndrome in a goat with a thymoma in the chest (Byas et al. 2019). The animal showed severe scaling and ulceration over 60% of the body, especially the back, ventral abdomen, coronary bands, and dewclaws. Histology revealed cell-rich inflammation at the dermal-epidermal junction, as well as superficial bacteria and yeast.
Lichenoid Dermatitis and Ichthyosis
This idiopathic condition was reported in a 2-year-old Boer buck in Israel (Yeruham et al. 2002). Pruritic