Open Veterinary Journal

Open Veterinary Journal

Peer-Reviewed Journal 
ISSN 2218-6050 (Online), ISSN 2226-4485 (Print) 

"Original Research"

Iodine-restricted food versus pharmacological therapy in the management of feline hyperthyroidism: A controlled trial in 34 cats

Giorgio Grossi(1), Andrea Zoia(2), Paola Palagiano(3), Nadia Leoni(4), Federica Bubini-Regini(5), Eleonora Malerba(1), Angelo Peli(1), Giacomo Biagi(1) and Federico Fracassi(1*)

1- Department of Veterinary Medical Sciences, University of Bologna, Italy

2- San Marco Veterinary Clinic, Padova, Italy

3- Meda Veterinary Clinic, Meda, Italy

4- San Siro Veterinary Clinic, Milano, Italy

5- Practitioner, Venezia, Italy


Background: Hyperthyroidism is a common endocrinopathy of middle-aged and elderly cats. A dietary treatment has been proposed as alternative to traditional therapies.

Aim: The aim of this prospective study was to compare the efficacy of an iodine-restricted food versus pharmacological therapy with methimazole in client-owned cats with hyperthyroidism.

Methods: Indoor cats with newly diagnosed hyperthyroidism (consistent clinical signs and serum total thyroxine concentration greater than 50 nmol/L) were assigned to one of three groups: (A) received an iodine-restricted food as a single therapy; (B) received transdermal methimazole in pluronic lecithin organogel; (C) received oral methimazole. In all groups clinical parameters, biochemistry and serum total thyroxine were evaluated at baseline and 10, 30, 60, and 90 days after treatment began.

Results: Thirty-four cats were enrolled in the study (group A: n=14; group B: n=11; group C: n=9). No significant differences were found between groups at diagnosis for signalment, clinical and laboratory findings, including serum total thyroxine concentrations. In all groups, serum total thyroxine concentration decreased significantly following the baseline measurement. After 90 days treatment, serum creatinine increased significantly only in the methimazole-treated groups. Liver enzyme activities decreased significantly only in group B, while no significant decreases were detected in groups A and C at any time.

Conclusion: These results suggest that iodine-restricted food is effective at reducing the total thyroxine concentration in the serum of hyperthyroid cats. Moreover, the iodine-restricted food did not cause any increase of serum creatinine concentrations and failed to improve liver enzymes abnormalities. These findings could indicate a persistent hyperthyroid state in cats treated with iodine-restricted food despite normalization of serum total thyroxine concentrations.

Keywords: Iodine-restricted food, Liver enzymes, Methimazole, Pluronic lecithin organogel, Thyroxine.

Cite this paper:

Grossi, G., Zoia, A., Palagiano, P., Leoni, N., Bubini-Regini, F., Malerba, E., Peli, A., Biagi, G. and Fracassi, F. 2019. Iodine-restricted food versus pharmacological therapy in the management of feline hyperthyroidism: A controlled trial in 34 cats. Open Vet. J. 9(3), 196-204.