DERMATOLIGIC DISEASES Main
I. Nasal Dermatitis (Sorenose)
A. Etiology: Unknown, although trauma, stress, hypersecretion or accumulation of Harderian gland secretions, and superficial bacterial infections (i.e., Staphylococcus sp.) have all been associated with the development of lesions. Incidence of disease is higher in weanlings than in adults. Nasal dermatitis is a fairly common disease problem in gerbils.B. Pathogenesis: Stresses such as overcrowding, weaning, and environmental variations can cause an increased secretion of porphyrin-containing fluid from the Harderian gland. Accumulation of these secretions around the external nares and eyes may result in irritation, self-induced trauma, and secondary bacterial infections.
C. Clinical Signs: Alopecia, erythema, focal dermatitis, and frequent scab and ulcer formation are all features of the typical case. The perinasal area is normally affected most severely, at least in early cases (see photo). The periocular region frequently becomes involved in more chronic cases. A well-established, moist, ulcerative dermatitis can spread to involve the remainder of the head, the forelimbs, and the ventrum of the chest and abdomen.
D. Diagnosis: A history of recent stress and possibly mechanical injury, together with clinical signs, are usually diagnostic. Harderian gland secretions appear as a red-brown crust, and are often misdiagnosed as nasal or ocular hemorrhage.
E. Treatment and Control: This disease is normally self-limiting when the predisposing stress factor has been removed. In cases where secondary bacterial infections have become established, topical or systemic antibiotics can be used (i.e., Chloramphenical 1% ophthalmic ointment applied to lesion every 8 hr). Avoid using antibiotics that contain aminoglycosides, as the gerbil has been reported to succumb to aminoglycoside toxicity when dosed at levels considered therapeutic in other species. A study of managerial practices, and reduction of environmental and husbandry stresses will aid in control of the disease.Parasitism of the gerbil rarely causes clinical disease problems. Alopecia in aged or debilitated gerbils may be due to demodicosis (A.). Scrapes of affected areas may reveal hamster demodectic mange mites, Demodex aurati or Demodex criceti (B.)
An unkempt, matted hair coat is often an indicator of excessive humidity levels in the environment (50% relative humidity). (Rough looking hair is also the most frequent physical reflection of active disease in most rodents.) This problem is often seen in animals kept in solid-topped aquariums or microisolator cages. Adequate air exchange to remove excess moisture is the best preventative measure.
Barbering of the tail hairs is observed in cages that are overcrowded. The hair grows back once the cage population is diminished. Fractures of the tail vertebrae, and slipping of the tail skin can all occur with improper handling (A.). This usually involves picking up animals by the distal portion of the tail. Surgical amputation with cautery (silver nitrate cautery shown in B.) supportive post-surgical care may be necessary when large amounts of tissue are compromised. Such injuries may be prevented by handling animals by the base of the tail.
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