A 38-g, intact female Siberian hamster (Phodopus sungorus) of unknown age was presented to the Tufts Cummings School of Veterinary Medicine Exotics Service with a history of pruritus and reddening of the facial area and distal extremities. The clinical signs and lesions had been present when the owner obtained the hamster from a pet store 3 weeks earlier.
A local veterinarian had evaluated the hamster. She had scanned the skin and fur using an ultraviolet light (Wood's lamp) and had made Gram-stained impression smears from affected areas of skin. The ultraviolet light scan did not show any areas of fluorescence and was interpreted to indicate that dermatophytes were not present. Microscopic examination of the skin impression smears had shown clusters of large, Gram-positive cocci. The veterinarian had treated the hamster with ivermectin (0.4 mg per kg body weight, administered subcutaneously) for possible skin parasites and had sent the animal home with trimethoprim-sulfa antibiotic (30 mg per kg body weight to be administered orally every 12 h) and triple antibiotic ointment (to be applied topically three times per d). After 3 weeks of treatment, the cutaneous lesions had not resolved.
When we saw the hamster, the owner reported that it was doing well, was active and was eating and drinking. On physical examination, we found the hamster was bright and alert. It was eating and passing normal stools. We found skin lesions on the left side of the nose and mouth and on all four limbs, primarily localized to the paws (Fig. 1). The skin lesions were erythematous, mildly ulcerated and excoriated. The claws on all paws were elongated and deformed.
Our differential diagnoses for dermatitis in a hamster included infection such as pyoderma, ectoparasitism or dermatophytosis; neoplasia, primarily lymphoma or other round cell tumor; endocrine disorder such as hyperadrenocorticism; metabolic disorder such as renal failure; dietary deficiency, primarily pyridoxine; and husbandry-related trauma such as irritating or abrasive bedding.
We frequently take a full-thickness skin biopsy sample to use as a primary diagnostic tool in pet rodents with skin lesions. This avoids the need to take blood samples from small, often emaciated patients and can help to rule out most of the diagnoses on our differential list.
We anesthetized the hamster using sevoflurane gas delivered by a facemask. For the duration of the procedure, the hamster was laid on a warm pad. We supplemented general anesthesia with local anesthesia of the biopsy site by injecting 2% lidocaine circumferentially subcutaneously in the distal right forelimb. We collected a 2.0-mm punch biopsy sample from an active skin lesion. The biopsy site was closed using sterile surgical tissue glue. The biopsy sample was fixed in 10% neutral-buffered formalin. We gave the hamster fluids (lactated Ringers solution, 100 ml per kg body weight administered subcutaneously) and meloxicam (0.2 mg per kg body weight administered subcutaneously) for post-operative analgesia. The hamster recovered uneventfully from the procedure. Pending biopsy results, treatment with enrofloxacin (Baytril, 10 mg per kg body weight administered orally every 12 h) was initiated.boxed-text
What are your differential diagnoses? Is the condition metabolic, infectious or neoplastic?
Column Editor's Note There is some confusion over the common names of Phodopus species. Until about 1980, Phodopus sungorus was considered to have two subspecies: Phodopus sungorus sungorus and Phodopus sungorus campbelli. Phodopus sungorus sungorus was known as the Djungarian hamster. There was no commonly used name for Phodopus sungorus campbelli. Then studies showed that these two subspecies were, in fact, different species, and they were renamed Phodopus sungorus and Phodopus campbelli, respectively. Phodopus sungorus was then referred to as the Siberian hamster and Phodopus campbelli as the Djungarian hamster. In the scientific literature, both the older and newer common names are used.
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Eshar, D., Mayer, J. & Keating, J. Dermatitis in a Siberian hamster (Phodopus sungorus). Lab Anim 39, 71 (2010). https://doi.org/10.1038/laban0310-71