Neoplasia and Proliferative Lesions of New World Camelids: A Systematic Literature Review and Retrospective Study of Cases Submitted to Colorado State University From 1995 to 2020

Abstract

Camelid pathology submissions to veterinary diagnostic laboratories are on the rise given the increasing popularity and population of llamas and alpacas especially in the western United States. When compared to other animals, the field of camelid neoplasia has a relative paucity of cases reported in the literature. The Colorado State University Veterinary Diagnostic Laboratories (CSU-VDL) has had a steady increase in the numbers of camelid pathology submissions allowing for a robust review of diagnoses of neoplasia in new world camelids. Here we present a retrospective analysis of camelid neoplastic and proliferative lesions diagnosed at the CSU-VDL from 1995 to 2020, followed by an extensive literature review. Results show increasing incidence of camelid neoplasia reported in the literature, therefore becoming a common diagnosis in llamas and alpacas. Proliferative and neoplastic lesions were diagnosed in 8.8% of new world camelid submissions to CSU-VDL with the most common tumors being lymphomas, squamous cell carcinomas, fibromas, and adenocarcinomas. Risk factors are female sex and increased age except in the case of lymphoma, which tends to occur in younger camelids. Lymphomas, melanomas, and adenocarcinomas (especially of gastrointestinal tract) carry an increased risk of multiple-organ system involvement often with widespread metastases. Conditions described in camelids for the first time include osteosarcoma, cutaneous hemangiosarcoma, myxosarcoma, pilomatricoma, ovarian theca cell tumor, congenital nevus with malignant transformation, and various other neoplasia. This article will provide an operational guide for camelid neoplasia to further assist veterinary laboratory diagnosticians, researchers, and practicing veterinarians in the field of camelid medicine and pathology.

Multicentric malignant round cell tumour in a cria: Clinical presentation, pathologic findings and differential diagnoses

“…MRCTs described in llamas and alpacas consist mostly of lymphoma and PMRCT, the former being the most frequently reported 1,3,4,6–9,17 …”

“…The age range of lymphoma detection is extremely broad, and it has been diagnosed in juveniles less than 1 month as well as in adults up to 23 years of age. There is also a single case of multicentric T‐cell lymphoma reported in a fetus in late‐stage gestation 1,3–13,15–19,21–24 …”

“…Besides the economic value of their fine quality coat, the diffusion of these species has been growing in recent years as they are suitable, for example, both as companion and pack animals, as integrated sheep protection, as tourist attraction and in pet therapy. Hence, the frequency of animal movement for breeding and exhibition has also grown steadily, and consequently, health problems are increasingly detected 1–3 …”

Postmortem diagnoses in South American camelids and factors influencing diagnostic rate in the Upper Midwest USA, 2009–2019

“…The age range for lymphoma cases in our study was 4-13 y, which is older than age ranges identified in other retrospective studies. 1,18 The mean age of SACs diagnosed with neoplasia in our dataset was 9.0 ± 5.7 y, and all animals identified with neoplasia were alpacas.…”

“…Neoplasia was diagnosed in 5.2% of the submissions in our study (Table 2), which is within the range reported in other regions (3.0–8.8%). 1,12,15,18 The most common neoplasm was lymphoma (4 of 8 total neoplasms diagnosed), which is more frequently identified in young SACs. The age range for lymphoma cases in our study was 4–13 y, which is older than age ranges identified in other retrospective studies.…”