Diagnosis and Treatment of Hyperthyroidism in a Guanaco (Lama guanicoe)
American Association of Zoo Veterinarians Conference 2017
Christina E. McCullough1, DVM, MLAS; Matt D. Miesner1, DVM, MS, DACVIM; Jessie D. Monday2, DVM, MS
1Veterinary Health Center, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA; 2Texas A&M Veterinary Medical Diagnostic Laboratory, Amarillo, TX, USA


This is the first reported diagnosis and treatment of hyperthyroidism in a camelid. A guanaco (Lama guanicoe) is a nondomestic relative of the llama (Lama glama).2 Guanacos are native to the mountainous regions of South America, have entered the United States through the pet trade, and are popular exhibit animals.1 A privately owned guanaco presented to the Veterinary Health Center at Kansas State University for a swelling located on the proximal, ventral neck. Ultrasound and cytology revealed a cyst-like structure with proteinaceous fluid, macrophagic inflammation, and epithelial proliferation. A diagnosis of hyperplastic or neoplastic parenchyma was proposed. The initial total thyroxine (T4) and triiodothyronine (T3) results were 176 nmol/L and >4.7 nmol/L, respectively. Patient T4 and T3 levels were subsequently run in sequence with a healthy companion (171 nmol/L, >4.7 nmol/L; 106 nmol/L, 1.1 nmol/L), and the patient’s thyroid levels were considered elevated. Nuclear scintigraphy was performed, and the radiopharmaceutical uptake indicated hyperactive tissue in the lateral margins of the left and right thyroid gland. Treatment included a subcutaneous injection of radioactive iodine therapy (I131) at a dose of 50 mCi. Two- and 8-week recheck exams showed declining T4 levels but were maintained within camelid reference ranges. Fourteen months post I131 treatment, the patient experienced a hypothyroid event (T4: 9 nmol/L; T3: 0 nmol/L). Levothyroxine was initiated at 0.06 mg/kg SID for 1 month. At a 4-month recheck, the patient was clinically healthy, the swelling had regressed, and T4 levels were consistent with those post I131 treatment.


The authors would like to thank the radiology department at Kansas State University, College of Veterinary Medicine for their assistance with advanced imaging and radioactive therapy treatment of the guanaco. As well as Dr. Kent Refsal, DVM, PhD, from the Michigan State University Diagnostic Center for Population and Animal Health, for compiling the 10-year camelid thyroid ranges.

Literature Cited

1.  Bravo PW. Camelidae. In: Miller RE, Fowler ME, eds. Fowler’s Zoo and Wild Animal Medicine. Volume 8. St. Louis, MO: Elsevier Saunders; 2014:592–602.

2.  Kadwell M, Fernandez M, Stanley HF, Baldi R, Wheeler JC, Rosadio R, Bruford MW. Genetic analysis reveals the wild ancestors of the llama and the alpaca. Proc Biol Sci. 2001;268:2575–2584.


Speaker Information
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Christina E. McCullough, DVM, MLAS
Veterinary Health Center
College of Veterinary Medicine
Kansas State University
Manhattan, KS, USA

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