Nasal Dermatitis (Sorenose): 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. 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. 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. 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. 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.
Tyzzer's Disease: Clostridium piliforme is a gram-negative, pleomorphic, obligate intracellular bacteria that produces spores. The incidence of spontaneous disease is quite low, occurring in sporadic outbreaks. Infection occurs by contact with infected animals or bedding, via the fecal-oral route. Unlike most other rodents and rabbits, gerbils are innately susceptible to expressing overt Tyzzer's disease without a need for physiologic stress or steroid therapy to aid in disease development. This is an acute, usually fatal, enterohepatic disease in gerbils. In colony situations, high mortality rates can occur with some animals exhibiting depression, unthrifty appearance, and varying degrees of watery diarrhea. Morbidity and mortality is highest in young gerbils and pregnant females, although all age groups can be affected. Pathology and Diagnosis: Grossly, multiple white foci of necrosis in the liver with mild to moderate enteritis, serosal edema, and possible brain and cardiac involvement may all appear in affected animals. Coagulative liver necrosis with minimal inflammatory cell infiltrate (arrows) is observed on histopathologic examination of the liver. Definitive diagnosis is made by demonstration of the organism in hepatocytes (arrows) surrounding necrotic foci of the liver or intestine sections stained by silver, PAS, or Giemsa methods. No treatment is effective once the disease is clinically apparent due to the intracellular nature of the organism and its ability to sporulate. Treatment with tetracycline may decrease mortality. Control is achieved by strict sanitation and the reduction of environmental and experimental stress and/or by elimination of exposed and symptomatic animals. Disinfection of cages and equipment is best accomplished with sporocidal disinfectants such as 1% bleach solutions.
Gerbil Enteritis: Salmonella enteritidis, along with protozoal infestation, and food deprivation, have all been reported to be causes of enteritis in gerbils. The affected animal may rarely have moderate to severe diarrhea, but frequently displays a rough hair coat, weight loss, depression, and dehydration. Acute death will sometimes be encountered. Gross lesions may include a congested liver, gastrointestinal distension, and a fibrinosuppurative peritonitis in gerbils with salmonellosis. Positive culture of Salmonella sp. should indicate concern for personnel safety. No treatment has been reported to be effective and severely affected colonies should be depopulated.