The feline iodine requirement is lower than the 2006 NRC recommended allowance

Abstract

The purpose of this study was to determine the iodine (I) requirement in adult cats. Forty-two healthy euthyroid cats (1.6-13.6 years old) were utilized in a randomized complete block design. Cats were fed a dry basal diet (0.23 mg/kg I) for a minimum of 1 month (pre-test) then switched to a different basal diet supplemented with seven levels of KI for 1 year (experimental period). Analysed I concentrations were 0.17, 0.23, 0.47, 1.1, 3.1, 6.9 and 8.8 mg I/kg diet [dry matter (DM) basis] and used to construct a response curve. Response variables included I concentrations in serum, urine and faeces, urinary I:creatinine ratio, I balance, technetium(99m) pertechnetate (Tc(99m)) thyroid:salivary ratio, complete blood count and serum chemistries as well as serum thyroid hormone profiles. No significant changes in food intake, weight gain or clinical signs were noted. Serum I, daily urinary I, daily faecal I and urinary I:creatinine ratio were linear functions of iodine intake. An estimate of the I requirement (i.e. breakpoint) was determined from regression of Tc(99m) thyroid:salivary ratio (scintigraphy) on I intake at 12 months [0.46 mg I/kg diet (DM basis) as well as 9 months I balance (0.44 mg I/kg diet (DM)]. The I requirement estimate determined in our study at 12 months for adult cats (0.46 mg I/kg) was higher than current Association of American Feed Control Officials (AAFCO) recommendations (e.g. 0.35 mg I/kg), but was lower than the 2006 National Research Council (NRC) I recommended allowance (e.g. 1.4 mg I/kg).

Effects of an iodine-restricted food on client-owned cats with hyperthyroidism

“…Another limitation is that the 2-month duration of the study was relatively short, and possible long-term side effects may have been missed. Further studies are needed to assess the long-term effect of iodine-restricted food in cats, although no side effects have been reported by Wedekind et al 19 who fed six cats a diet with 0.15 ppm dry matter iodine and six cats a diet with 0.24 ppm dry matter iodine for a 1-year period.…”

Effect of Feeding an Iodine‐Restricted Diet in Cats with Spontaneous Hyperthyroidism

“…Iodine content of both the canned and dry form of the diet is 0.2 ppm (μg/kg). Association of American Feed Control Officials (AAFCO) guidelines in 2008 and National Research Council (NRC) guidelines in 2006 have minimum recommendations for iodine content of commercial diets of 0.35 ppm and 1.4 ppm, respectively. The protein content for both the dry and wet formulations is 8.2 g/100 kcal.…”

Feline Hyperthyroidism

“…Published guidelines for iodine requirements for healthy cats have changed over the years, but current recommendations are that healthy cats should consume at least 0.46 mg/kg of dry food (Wedekind et al, 2010). Published guidelines for iodine requirements for healthy cats have changed over the years, but current recommendations are that healthy cats should consume at least 0.46 mg/kg of dry food (Wedekind et al, 2010).…”