Background: Reversible antioxidant depletion is found in hyperthyroid humans, and antioxidant depletion increases the risk of methimazole toxicosis in rats.Objectives: To determine whether abnormalities in concentrations of blood antioxidants or urinary isoprostanes were present in hyperthyroid cats, and were reversible after radioiodine treatment. To determine whether or not antioxidant abnormalities were associated with idiosyncratic methimazole toxicosis.Animals: Hyperthyroid cats presented for radioiodine treatment (n = 44) and healthy mature adult control cats (n = 37).Methods: Prospective, controlled, observational study. Red blood cell glutathione (GSH), plasma ascorbate (AA), plasma free retinol (vitamin A), a-tocopherol (vitamin E), and urinary free 8-isoprostanes in hyperthyroid cats were compared to healthy cats and to hyperthyroid cats 2 months after treatment.Results: Blood antioxidants were not significantly different in hyperthyroid cats (mean GSH 1.6 ± 0.3 mM; AA 12.8 ± 4.9 lM, and vitamin E, 25 ± 14 lg/mL) compared to controls (GSH 1.4 ± 0.4 mM; AA 15.0 ± 6.6 lM, and vitamin E, 25 ± 17 lg/mL). Urinary isoprostanes were increased in hyperthyroid cats (292 ± 211 pg/mg creatinine) compared to controls (169 ± 82 pg/mg; P = .006), particularly in hyperthyroid cats with a USG < 1.035. Plasma free vitamin A was higher in hyperthyroid cats (0.54 ± 0.28 lg/mL versus 0.38 ± 0.21 in controls; P = .007). Both abnormalities normalized after radioiodine treatment. No association was found between oxidative status and prior idiosyncratic methimazole toxicosis.Conclusion and Clinical Importance: Increased urinary isoprostane could reflect reversible renal oxidative stress induced by hyperthyroidism, and this requires additional evaluation.

Previous reports of true pancreatic cysts in cats have suggested that pancreatic cysts in cats are benign incidental findings. This case report describes the progressive clinical course and diagnostic findings in a cat with multiple recurrent pancreatic cysts. The presenting clinical signs included diarrhea, intermittent vomiting, polyphagia, and marked weight loss. Pancreatic cysts were identified via abdominal ultrasound and computed tomography (CT). An exploratory celiotomy and lesion histopathology confirmed multiple true pancreatic cysts of unknown etiology. One month after surgery the cat presented for lethargy and decreased appetite. Clinical re-evaluation was diagnostic for diabetes mellitus and an abdominal ultrasound confirmed recurrence of the pancreatic cysts. The recurrent nature of the pancreatic cysts and the concurrent development of diabetes mellitus were suggestive of progressive loss of pancreatic function or insulin resistance. This is the first described case of multiple recurring pancreatic cysts in a cat associated with pancreatic inflammation, atrophy and endocrine dysfunction.