Data from: Pathology and epidemiology of ceruminous gland tumors among endangered Santa Catalina Island foxes (Urocyon littoralis catalinae) in the Channel Islands, USA

In this study, we examined the prevalence, pathology, and epidemiology of tumors in free-ranging island foxes occurring on three islands in the California Channel Islands, USA. We found a remarkably high prevalence of ceruminous gland tumors in endangered foxes (Urocyon littoralis catalinae) occurring on Santa Catalina Island (SCA) - 48.9% of the dead foxes examined from 2001-2008 had tumors in their ears, and tumors were found in 52.2% of randomly-selected mature (≥ 4 years) foxes captured in 2007-2008, representing one of the highest prevalences of tumors ever documented in a wildlife population. In contrast, no tumors were detected in foxes from San Nicolas Island or San Clemente Island, although ear mites (Otodectes cynotis), a predisposing factor for ceruminous gland tumors in dogs and cats, were highly prevalent on all three islands. On SCA, otitis externa secondary to ear mite infection was highly correlated with ceruminous gland hyperplasia (CGH), and tumors were significantly associated with the severity of CGH, ceruminous gland dysplasia, and age group (older foxes). We propose a conceptual model for the formation of ceruminous gland tumors in foxes on SCA that is based on persistent, ubiquitous infection with ear mites, and an innate, over exuberant inflammatory and hyperplastic response of SCA foxes to these mites. Foxes on SCA are now opportunistically treated with acaricides in an attempt to reduce mite infections and the morbidity and mortality associated with this highly prevalent tumor.

本研究针对美国加利福尼亚海峡群岛三座岛屿上的野生岛屿灰狐，系统调查了其肿瘤的患病率、病理学特征与流行病学规律。我们在圣卡塔利娜岛（Santa Catalina Island, SCA）的濒危圣卡塔利娜岛灰狐（Urocyon littoralis catalinae）中发现了极高的耵聍腺肿瘤（ceruminous gland tumors）患病率：2001至2008年间剖检的死亡灰狐中，48.9%耳部存在肿瘤；2007至2008年随机捕获的成熟（≥4岁）个体中，52.2%检出肿瘤，这是目前野生种群中记录到的最高肿瘤患病率之一。与之形成鲜明对比的是，圣尼古拉斯岛与圣克莱门特岛的灰狐均未检出任何肿瘤；尽管耳痒螨（Otodectes cynotis）——犬与猫耵聍腺肿瘤的易感诱因——在三座岛屿上均呈高度流行态势。在圣卡塔利娜岛，耳痒螨感染继发的外耳炎与耵聍腺增生（ceruminous gland hyperplasia, CGH）呈显著相关；肿瘤发生亦与CGH严重程度、耵聍腺发育异常以及年龄分层（老龄灰狐）显著相关。我们构建了圣卡塔利娜岛灰狐耵聍腺肿瘤发生的概念模型，该模型基于耳痒螨的持续性、广泛性感染，以及圣卡塔利娜岛灰狐对该螨的先天过度亢进炎症与增生反应。目前，研究团队正对圣卡塔利娜岛的灰狐开展杀螨剂（acaricides）机会性治疗，以降低耳痒螨感染率，并缓解这一高流行肿瘤所导致的发病与死亡情况。