PVM Scholar Examines Iodine in Feline Diets

Dr. Catharine Scott-Moncrieff
Dr. Catharine Scott-Moncrieff

Hyperthyroidism is one of the most common diseases of older cats, and the prevalence has been increasing since the late 1970s. Iodine is essential for the synthesis of thyroid hormones, and it is possible that hyperthyroidism is related to the amount of iodine in cat food. As reported in “Elemental,” the annual report produced by the Purdue Office of the Executive Vice President for Research and Partnerships, Purdue Veterinary Medicine Professor of Small Animal Internal Medicine Catharine Scott-Moncrieff, a specialist in endocrinology and head of the Department of Veterinary Clinical Sciences, is looking for an answer to this question from a variety of angles. If left untreated, a hyperthyroid cat may exhibit excessive hunger, vomiting, diarrhea, nervousness, unkempt hair coat and tachycardia. Treatment options for hyperthyroid cats include administration of oral anti-thyroid drugs, thyroidectomy or administration of radioactive iodine.

A diet containing a restricted amount of iodine has been shown to decrease thyroid hormone concentrations and improve clinical signs in hyperthyroid cats. Iodine content of cat food varies widely among commercial cat foods, especially in canned cat food. Dr. Scott-Moncrieff and co-authors have called for a review of iodine supplementation standards used in commercial cat foods. “This research has resulted in improved recommendations for the use of iodine-limited diets for management of hyperthyroidism in cats and has the potential to lead to a greater understanding of the pathogenesis of hyperthyroidism in cats,” Dr. Scott-Moncrieff said. 

Click here to view the on-line version of the publication “Elemental”, which organizes reports about Purdue research projects on the basis of the “elements” involved.  In addition to iodine, another element discussed is the focus of research conducted by Professor Emeritus of Veterinary Clinical Sciences David Waters, who studied the correlation between selenium and prostate cancer.  “With selenium, it’s easy to over-supplement,” said Dr. Waters, who serves as director of the Gerald P. Murphy Cancer Foundation in the Purdue Research Park in West Lafayette.  He points to the results of one of his research team’s studies, reported in the peer-reviewed scientific journal BioFactors.  In controlled laboratory experiments, selenium triggered the elimination of prostate cells with the most genetic damage — a kind of “homeostatic housecleaning” process that helps keep cancer at bay.

PVM Professor Emeritus David Waters
PVM Professor Emeritus David Waters

But that only happened at mid-range selenium levels, Dr. Waters explained. If you imagine the letter “U,” with one tip being very high selenium levels and the other tip being very low, the ideal level seems to be the trough of the curve. “Measuring selenium status and then titrating selenium levels to mid-range status would seem to offer men a practical and informed approach, rather than blindly taking selenium supplements and risking the downside of unnecessary over-supplementation,” Dr. Waters wrote for the medical website UroToday.


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