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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #133329
Title: PREVALENCE, PATHOLOGY, AND PATHOGENESIS OF CYSTIC THYROIDS IN LLAMAS (LAMA GLAMA)

Author
item Hamir, Amirali
item TIMM, KAREN - OREGON STATE UNIVERSITY

Submitted to: Veterinary Record
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: This article documents the prevalance and changes associated with fluid-filled cysts in thyroid glands of llamas. During a period of 2.5 years (1995 - 1998), 88 South American camelids from northwest United States were examined. Eleven were alpacas and 77 were llamas. There were either bilateral or unilateral fluid-filled cysts seen in thyroids of 15 llamas. Fourteen were females and 1 was a male. Cut section of the affected thyroids revealed single or multiple cavities, which usually contained yellowish clear material. Within the cysts there was an extensive accumulation of fluid material. Based on the laboratory findings of cystic and non-cystic thyroids, it is suggested that the cysts originate within small tumors (adenomas). These cysts enlarge by fusing together to form larger cysts. Thyroid cysts have not previously been reported in South American camelids. Although none of the llamas in our investigation showed clinical signs of thyroid disfunction, many of the animals in the study were donated because the females were barren after repeated breedings with known fertile males. Many of these older females had previously had crias of their own. Therefore, it is speculated that the high prevalence of thyroid cysts present in the examined population of llama may partially be responsible for the inability of the females to successfully reproduce.

Technical Abstract: Prevalance and pathological changes associated with thyroid cysts in llamas is documented. During a period of 2.5 years (1995 - 1998), necropsy examinations were performed on 88 South American camelids from northwest United States. Eleven were alpacas and 77 were llamas. Grossly either bilateral or unilateral fluid-filled cysts were seen in thyroids of 15 llamas. Fourteen were females and 1 was a male. Cut section of the affected thyroids revealed single or multiple cavities, which usually contained yellowish clear material. Microscopic examinations of the cystic thyroids revealed an extensive accumulation of colloidal material and lining by intact thyroid follicles and strands of free floating follicular epithelium. Based on the microscopic findings of grossly cystic and non-cystic thyroids it is suggested that the cysts originate within small follicular adenomas. These cysts enlarge by fusing together to form larger cysts which eventually result in large macroscopic cysts. Thyroid cysts have not previously been reported in South American camelids.