There is only limited published information on diseases of hedgehogs, including neoplastic disease.2,4,6,8,9,10,11 Most of these publications are individual case reports with a few involving multiple animals. Certain types of sarcomas in hedgehogs have been associated with retroviral infection.3,5 In two previous retrospective studies concerning necropsy findings in hedgehogs, neoplastic disease was noted in approximately 30% of hedgehog necropsies.1,7 The present study summarizes a series of tumors diagnosed in captive African hedgehogs and includes several tumors that have never been previously reported in hedgehogs.
Specimens were obtained from a total of 97 hedgehog submissions recorded at Northwest ZooPath (NZP) from 1994 to 2000. Sixty of the 97 hedgehogs were from zoologic parks and 37 were privately owned. Thirty-nine of the 97 hedgehogs were male, 46 female, and 12 of unknown gender. All were adult (>1 year old). The tumors were classified according to histomorphologic features and the presence or absence of metastases. For evaluating possible gender predisposition, χ2 test was performed and a p-value ≤0.05 was considered significant.
Neoplastic disease was diagnosed in 50 (51.5%) of the 97 hedgehogs, and four of these 50 animals had more than one type of tumor. Twenty-two of the hedgehogs with tumors were female, 16 were male, and 12 were of unknown gender. The occurrence of tumors was unrelated to gender (p≥0.25). The median age at time of tumor diagnosis was 3.5 years with a range of 2–5.5 years. The average life expectance for hedgehogs in captivity is approximately 3–5 years. Seventeen of the hedgehogs with tumors were of unreported age and were classified as adult (>1 year old). Thirty-one hedgehogs were from zoologic parks and 19 were privately owned. Of a total of 56 tumors diagnosed, 11 were classified as mesenchymal, 29 as epithelial, and 16 as discrete round cell neoplasms.
Fifty (89%) of 56 tumors were classified as malignant and six (11%) as benign. The diagnosis of a malignant tumor usually warranted a guarded to poor prognosis. The body systems in which the tumors were found (in order of frequency of occurrence) were as follows: integumentary (18 tumors), hemolymphatic (12 tumors), digestive (nine tumors), endocrine (eight tumors), genital (six tumors), musculoskeletal (two tumors), and nervous (one tumor).
The most commonly diagnosed tumors were mammary gland tumor (nine), lymphosarcoma (eight), and oral squamous cell carcinoma (seven). Mammary tumors were usually malignant and presented as large, subcutaneous swelling along the ventral thorax and abdomen. In three cases, the mammary tumor reoccurred within six months of surgical removal. Five of the eight cases of lymphosarcoma were of the multicentric form and the other three were of the alimentary form. Diarrhea and weight loss were common clinical signs in hedgehogs with gastrointestinal lymphosarcoma. Cases of oral squamous cell carcinoma (SCC) usually presented as swelling of the maxillary or mandibular gingiva. Hedgehogs with oral SCC presented with loose teeth, tooth loss, swollen gingiva, and/or gingivitis. In all cases, the tumor was locally infiltrative but there was no evidence of metastasis.
In conclusion, neoplastic disease is very common in adult African hedgehogs and occurs without gender preference. In the majority of cases, the neoplasms were malignant and usually carried a poor prognosis. The integumentary, hemolymphatic, digestive, and endocrine systems were the most common sites for tumors. Mammary gland carcinoma, lymphosarcoma, and oral SCC were the most common types of tumors.
We thank Roy Brown for technical assistance with histology, and the many veterinarians who submitted the cases for histopathology.
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