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Objectives: Urinary tract infections (UTIs) are reported to be relatively common in hyperthyroid cats, with prevalence rates ranging from 12% to 22%. Factors that are associated with UTIs include age, decreasing body weight and active urine sediments. The purpose of this study was to investigate the prevalence of positive urine cultures (PUCs) in hyperthyroid cats and associated risk factors for PUC. Methods: In total, 197 hyperthyroid cats presenting for radioiodine therapy had urine cultures prospectively performed on cystocentesis samples. Data pertaining to clinical signs, drug history, age, weight, blood urea nitrogen, creatinine, serum thyroxine and urinalysis were also evaluated. Results: The prevalence of PUCs in this population of hyperthyroid cats was 5.1% and all cats were subclinical. Microscopic bacteriuria was significantly associated with a PUC (60%) compared with a negative urine culture (1.6%) status. Age, weight, urine specific gravity <1.020, urine pH, hematuria, pyuria, thyroxine concentration, breed and sex were not associated with PUC status. Conclusions and relevance: The prevalence of PUCs in this population of cats was lower than previous reports of cats with hyperthyroidism. Cats with a PUC were subclinical at the time of culture, regardless of urine sediment abnormalities. Further studies are necessary to determine the clinical significance of subclinical bacteriuria in hyperthyroid cats. [ABSTRACT FROM AUTHOR]

Objectives: Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls. Methods: Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism. Results: Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group (P = 0.023). Conclusions and relevance: Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to evaluate symmetric dimethylarginine (SDMA) in hyperthyroid cats before and after treatment with radioactive iodine and to determine how pretreatment SDMA relates to the development of post-treatment azotemia. Methods: Eighty-four non-azotemic hyperthyroid cats had serum SDMA and creatinine evaluated before and 1, 3 and 6 months after treatment with radioiodine therapy. Results: Baseline SDMA was increased in 7% (n = 6/84) of cats, whereas SDMA was increased in 19% (n = 15/81), 20% (n = 16/80) and 32% (n = 26/81) at 1 month, 3 months and 6 months after treatment, respectively. Creatinine was not elevated in any of the cats at baseline because of the study design, and was elevated in 6% (n = 5/81), 15% (n = 12/80) and 15% (n = 12/81) of cats at 1, 3 and 6 months after treatment, respectively. SDMA (median 11 μg/dl, range 1–22 μg/dl) was significantly higher at 3 (12 μg/dl, range 6–45 μg/dl; P = 0.005) and 6 months (11 μg/dl, 6–25 μg/dl; P <0.001) compared with baseline (11 μg /dl, range 1–21 μg/dl). The median baseline SDMA was significantly higher in the azotemic group (13 μg/dl, range 11–22 μg/dl) compared with the non-azotemic group (10 μg/dl, range 1–21 μg/dl, P = 0.002). The sensitivity of SDMA for detecting azotemia after treatment was 15.4%, with a specificity of 94.4%. Baseline serum SDMA concentration had a moderately positive association with baseline creatinine concentration (P <0.001, r = 0.437). At 6 months, there was a strong positive correlation between SDMA and creatinine concentrations (P <0.001, r = 0.721). There was no significant correlation with SDMA and thyroxine at baseline (P = 0.772, r = −0.034) or 6 months (P = 0.492, r = −0.078). Conclusions and relevance: SDMA increases in cats treated for hyperthyroidism with radioactive iodine and likely reflects associated changes in glomerular filtration rate. An increased SDMA concentration above the reference interval prior to treatment has a high specificity but poor sensitivity for the prediction of post-treatment azotemia. [ABSTRACT FROM AUTHOR]

Iopanoic acid is an iodine containing oral cholecystographic agent that has been used to treat hyperthyroidism in humans and has recently been evaluated in an experimental model of feline hyperthyroidism. The aim of this study was to evaluate the efficacy of iopanoic acid in cats with spontaneous hyperthyroidism. Eleven cats were included in the study. Eight were treated initially with 50mg orally q 12h and three were treated with 100mg orally q 12h. Prior to treatment (baseline) and at 2, 4, and 12 weeks of treatment, owner questionnaires, physical exams, complete blood count, biochemistry analyses, and T3 and T4 concentrations were evaluated. The mean serum T3 concentration decreased with treatment at all time periods compared to baseline. Mean T4 concentrations were increased at weeks 4 and 12 compared to baseline. Five cats had a partial response during the initial 4 weeks of therapy, but the effects were transient and no significant improvements in clinical signs or physical exam findings were noted at any time period. Results suggest that iopanoic acid may be beneficial for acute management of thyrotoxicosis in some cats, but is not suitable for long-term management. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the safety and effect of iopanoic acid in 13 cats with hyperthyroidism induced by daily subcutaneous administration of 25μg/kg levothyroxine for a period of 42 days. On day 28 of levothyroxine administration, cats were randomly allocated to receive treatment twice daily with a placebo (control group; n =4), 50mg iopanoic acid (low dose group; n =5), or 100mg iopanoic acid (high dose group; n =4) for 14 days. Compared to the control group, T3 concentrations were significantly decreased in both the low dose and high dose groups on days 35 and 42. T3 concentrations in the low dose and high dose groups at days 35 and 42 were not different from day -8. The effect of iopanoic acid on clinical signs of hyperthyroidism was less apparent. Further clinical studies evaluating the long-term effect in cats with spontaneous hyperthyroidism are warranted. [Copyright &y& Elsevier]