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

Sinonasal chondrosarcoma in a llama

A 14-y-old intact female llama (Lama glama) was presented for evaluation of a right maxillary swelling of 3-mo duration. Clinically, the animal had mild nasal discharge, abnormal retropulsion of the right eye, and moderate gingival disease. An incisional biopsy of the maxillary mass revealed pleomorphic and mitotically active neoplastic spindle-to-stellate cells organized in haphazard lacunae embedded in abundant chondroid matrix. Given the poor prognosis, euthanasia was elected. Postmortem examination and sectioning of the head exposed a large solid, white, firm mass that vastly expanded the right infraorbital region, extending to the maxilla, effacing the right nasal conchae and ipsilateral zygomatic bone. Collectively, postmortem dissection, cytology, and histopathology of the primary mass supported a diagnosis of sinonasal chondrosarcoma. To our knowledge, this entity had not been reported previously in this species and should be considered a differential for facial deformities in New World camelids.

Fatal septicemia in 2 South American camelids with caudal C3-pyloric-duodenal adenocarcinoma

Gastrointestinal adenocarcinomas are often reported in South American camelids (SAC). We describe here cases of gastroduodenal adenocarcinoma in an adult alpaca (Vicugna pacos) and a llama (Llama glama); both SACs were anorectic and lethargic before death. At autopsy, a prominent and firm caudal C3-pyloric-duodenal junction with stricture and ulceration was present in both animals, as were hemorrhages in various organs and hydrothorax. Microscopically, scattered nests, cords, and tortuous acini of neoplastic epithelial cells were embedded in desmoplastic stroma and invaded the submucosa and muscle layers of the gastroduodenal junction. The mucosa was necrotic, with gram-negative rods in the alpaca and colonies of gram-positive cocci in the llama. No tumor metastases were observed. The neoplastic cells immunolabeled for pancytokeratin. Escherichia coli was isolated from the alpaca and Streptococcus lutetiensis from the llama; septicemia was the cause of death in both animals. Although adenocarcinomas arising from gastric compartments and intestinal segments have been reported in SACs, adenocarcinoma of the caudal C3-pyloric-duodenal junction has not been reported previously in these species, to our knowledge.

Hematologic parameters in female alpacas during age progression: a retrospective study

Alpacas, like all camelids, have elliptical red blood cells (RBCs) in contrast to other mammals. This particular shape is important for increased osmotic resistance and stability. Age-related changes in the RBC count are known in other species, with alterations in both red and white blood cells being described. In alpacas, there are few data on age-related changes, and only a comparison of crias with adult animals. We characterized age-related hematologic changes in a study of 21 female alpacas from a research herd. A total of 87 records of clinically healthy alpacas of different ages were statistically analyzed retrospectively from the hematologic records over a nine-year period. Significant positive correlations of age with hemoglobin (Hb), HCT, MCV, MCH, neutrophils, platelet-to-lymphocyte ratio (PLR), and neutrophil-to-lymphocyte ratio (NLR) were found as well as significant negative correlations of age with lymphocytes in addition to lymphocyte-to-monocyte ratio (LMR). A paired comparison of eight older animals in the herd at three different ages also showed significant differences in the parameters Hb, HCT, MCV, MCH, MCHC, lymphocytes, eosinophils and neutrophils. Similar changes in hematologic parameters have been reported in other species and should be taken into account when interpreting hematologic results in alpacas.

First detection of autochthonous Lamanema chavezi infections in llamas (Lama glama) in Europe

Lamanema chavezi is one of the most pathogenic nematode species of South American camelids (SAC), with a homoxenous life cycle involving enterohepatic migration of its larvae in the host. So far, it has been found in the Americas and New Zealand. The first autochthonous L. chavezi infections in SAC in Europe are reported here. On a SAC farm in Germany, a 15-month-old male llama with a short history of diarrhoea died in September 2017, followed nine months later by a three-year-old female llama with a history of emaciation, apathy, anorexia, anaemia and tetraparesis with retained sensorium. Both animals were born and raised on the farm, which had imported three llamas directly from Chile 4-14 years earlier. At necropsy, the main lesions in both cases were numerous white-yellow to dark red foci, up to 3 mm in size, close to the Glisson's capsule and deep in the parenchyma of the liver. Histologically, the livers showed haemorrhagic tracks by and with nematode larvae and a necro-haemorrhagic to fibrinous inflammation with a predominantly lymphohistiocytic infiltration. The larvae were 30-50 μm in diameter and had external longitudinal cuticular ridges. Larvae extracted from unfixed liver tissue were 1800-2000 μm long and about 80 μm in diameter, with a terminal spine at the posterior end, which is characteristic of female L. chavezi stages. The ribosomal DNA including the almost complete 18S rRNA gene, the first internal transcribed spacer, the 5.8S RNA gene, the second internal transcribed spacer (ITS) and the partial 28S rRNA gene from isolated larvae were amplified using nematode-specific oligonucleotide primers and then sequenced. The assembled nematode sequence of 3448 bp showed an identity of 99.4% to previously published L. chavezi sequences in the BLASTN search. Low numbers of L. chavezi-like eggs were found in the faeces of seven (29%) of 24 llamas and alpacas in the herd, including some farm-born crias, tested two years after the last fatal case. The results show for the first time that L. chavezi has not only been imported into Europe from South America, but has also completed its life cycle locally, resulting in autochthonous infections of SAC. This was also suspected to be the cause of the fatal disease in two llamas.

Intracranial embryonal neoplasm in an alpaca

An 11-y-old hembra alpaca was admitted because of cerebellar and vestibular signs, dysphagia, and aspiration pneumonia; without clinical improvement following empirical therapy, the patient was euthanized. On autopsy, a neoplasm was found incorporating the right vestibulocochlear nerve at the level of the acoustic meatus. Histologically, the mass was composed of a multiphasic primitive cell population associated with a dense fibrous stroma and enveloping a remnant ganglion and nerve bundles. Patterns included dense ribbons and cords of embryonal neuroepithelial cells admixed with loosely defined interlacing spindle cells. The embryonal cells had angular cell profiles with variable amounts of lightly basophilic cytoplasm, ovoid-to-irregular nuclei, and an open chromatin pattern with a typically inapparent nucleolus. Necrosis was not evident, and there was 1 mitotic figure per 2.37 mm2. The entire mass was infiltrated by small numbers of lymphocytes and plasma cells. Immunohistochemistry (IHC) revealed strong and diffuse cytoplasmic immunolabeling for vimentin, microtubule-associated protein-2, protein gene product 9.5, and synaptophysin; ~50% immunolabeling for cytokeratin AE1/3; sporadic OLIG2 and S100 immunolabeling; and absent glial fibrillary acidic protein immunolabeling. Based on the histologic pattern and the IHC results, our diagnosis was a poorly differentiated embryonal tumor with ependymal differentiation associated with the vestibulocochlear nerve.

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

South American camelids (SACs) have become increasingly popular as livestock and companion animals in the Midwestern United States. With increased ownership, postmortem evaluations and samples available for diagnostic assessment are being submitted more frequently to veterinary diagnostic laboratories. We searched archived pathology records at the Wisconsin Veterinary Diagnostic Laboratory (WVDL) between 2009-2019 for SAC cases. Postmortem records from 166 alpacas and 27 llamas were included, with an average of 1.42 diagnoses per animal. The overall average diagnostic rate was 79.8%. Abortion and neonatal cases (fetus to 1-wk-old) had the lowest diagnostic rate (33.3%) and was the only group with a diagnostic rate statistically significantly lower than the average. The most common diagnoses were gastrointestinal parasitism and suboptimal nutritional status or inanition; 78% of cases diagnosed with suboptimal nutritional status were also parasitized. The gastrointestinal parasites identified most frequently were Eimeria sp. and strongyles, especially Nematodirus sp. Our findings may aid allocation of diagnostic resources to better serve regional SAC populations and provide a framework for practitioners who send samples to laboratories for analysis. Submission of whole bodies, euthanized animals, fresh tissue, and inclusion of placental tissues in abortion cases are recommended for optimal diagnostic outcome.