A Multi-Institutional Collaboration to Understand Neoplasia, Treatment and Survival of Snakes

SIMPLE SUMMARY: Multiple studies have focused on types of neoplasia found in snakes, but an overall estimation of prevalence including total populations of animals at multiple facilities has not been conducted. Additionally, an in-depth evaluation of methods of therapy and survival of snakes with neoplasia has not been carried out. This study calculated the prevalence of tumors in 133 snakes, representing 65 different species, housed in six zoos and aquariums. Survival times were evaluated to determine whether these snakes were more likely to die from their tumors versus another cause. Treatment outcomes were evaluated to determine if the used treatment types lengthened the snakes’ life spans. Common or northern watersnakes (Nerodia sipedon), eastern diamond-backed rattlesnakes (Crotalus adamanteus), and timber rattlesnakes (Crotalus horridus) had the highest prevalence of tumors. Malignant (cancerous) tumors predominated, and the snakes with these tumors were significantly more likely to die of their cancer than those with benign tumors. Thirty-six of the 133 snakes received treatment for their tumors. There was no significant difference in survival times for those treated and not treated. This population is a subset of the overall snake population under managed human care, and a larger collection of snake tumor and population data could yield different results. Therefore, additional snake cases, along with other non-domestic species, are continuing to be curated in a database (Exotic Species Cancer Research Alliance tumor database). The goal of this data collection is to provide data on a select population of snakes to help veterinarians gain greater understanding of cancer types and to treat cancer in these animals. ABSTRACT: This multi-institutional collaborative study of neoplasia in snakes reviewed medical records of snakes at each facility to determine species prevalence, survival, and methods of treatment. Complete species numbers of snakes were also collected at each facility. In total, 65 species, 133 snakes, and 149 unique neoplasias were included in this study. Affected species, age, sex, and their tumor prevalence, tumor type and location, metastasis, treatment, and survival data are reported. The highest species-specific tumor prevalence was in Common or Northern Watersnakes (Nerodia sipedon) (30.8%, n = 4 of 13), Eastern Diamond-Backed Rattlesnakes (Crotalus adamanteus) (26.3%, n = 5 of 19), and Timber rattlesnakes (Crotalus horridus) (22.7%, n = 5 of 22). Malignant tumors predominated (86.6%, n = 129 of 149) with soft tissue sarcomas being the most common (30.2%, n = 45 of 149). Snakes with malignant neoplasia, metastases, or indeterminate presence of metastases were statistically more likely to die from their neoplasms than snakes having either benign neoplasia or no diagnosed metastases (p < 0.05). Gender, taxonomic family, and species of those evaluated did not significantly affect the outcome of snakes with neoplasia. Only 27.1% (n = 36 of 133) of snakes received a reported form of treatment and, for those treated, surgical excision was the most common treatment modality. There was not a significant difference in outcome based on treatment; however, surgery and chemotherapy were associated with death from a cause other than their tumor.