Diagnosis of Hyperthyroidism in Cats with Kidney Disease

Wakeling, J., K. Moore, et al. (2008). "Diagnosis of hyperthyroidism in cats with mild chronic kidney disease." Journal of Small Animal Practice 49(6): 287-294.


It is a well known phenomenon that hyperthyroid cats with concurrent non-thyroidal illness, such as chronic kidney disease (CKD), may have total thyroxine concentrations within the normal reference range. This causes a diagnostic dilemma. The objective of this study was to determine total thyroxine, free thyroxine and/or thyroid-stimulating hormone concentrations in cats with mild CKD. Three groups of cats were included: 16 cats with CKD and clinical signs compatible with hyperthyroidism but total thyroxine within the reference range (these cats were confirmed with hyperthyroidism at a later date); 20 cats with CKD and no signs of hyperthyroidism; 20 clinically healthy senior cats (over 8 years of age). Four of the 20 cats with CKD had free thyroxine concentrations that were borderline or high. Of the 16 cats with hyperthyroidism and CKD, free thyroxine was high in 15/16 cats and thyroid-stimulating hormone was low in all cats. The researchers conclude that the combined measurement of free thyroxine with total thyroxine or thyroid-stimulating hormone may be of merit in the diagnosis of hyperthyroidism in cats with chronic kidney disease.
>> PubMed abstract


Related articles:
Langston, C. E. and N. J. Reine (2006). "Hyperthyroidism and the kidney." Clin Tech Small Anim Pract 21(1): 17-21.
>> PubMed abstract


More on cat health: Winn Feline Foundation Library

Wakeling, J., K. Moore, et al. (2008). "Diagnosis of hyperthyroidism in cats with mild chronic kidney disease." Journal of Small Animal Practice 49(6): 287-294.


It is a well known phenomenon that hyperthyroid cats with concurrent non-thyroidal illness, such as chronic kidney disease (CKD), may have total thyroxine concentrations within the normal reference range. This causes a diagnostic dilemma. The objective of this study was to determine total thyroxine, free thyroxine and/or thyroid-stimulating hormone concentrations in cats with mild CKD. Three groups of cats were included: 16 cats with CKD and clinical signs compatible with hyperthyroidism but total thyroxine within the reference range (these cats were confirmed with hyperthyroidism at a later date); 20 cats with CKD and no signs of hyperthyroidism; 20 clinically healthy senior cats (over 8 years of age). Four of the 20 cats with CKD had free thyroxine concentrations that were borderline or high. Of the 16 cats with hyperthyroidism and CKD, free thyroxine was high in 15/16 cats and thyroid-stimulating hormone was low in all cats. The researchers conclude that the combined measurement of free thyroxine with total thyroxine or thyroid-stimulating hormone may be of merit in the diagnosis of hyperthyroidism in cats with chronic kidney disease.
>> PubMed abstract


Related articles:
Langston, C. E. and N. J. Reine (2006). "Hyperthyroidism and the kidney." Clin Tech Small Anim Pract 21(1): 17-21.
>> PubMed abstract


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Feline Large Granular Lymphocyte Lymphoma

Krick, E. L., L. Little, et al. (2008). "Description of clinical and pathological findings, treatment and outcome of feline large granular lymphocyte lymphoma (1996-2004)." Veterinary and Comparative Oncology 6(2): 102-110.

Large granular lymphocytes (LGL) can be found in the blood of healthy animals and usually constitute 10% or less of total circulating lymphocytes. Large granular lymphosarcoma/leukemia is a neoplastic disease of lymphocytes rarely seen in cats and dogs and is a distinct variation of lymphoma. Limited information exists regarding pathological and immunohistochemical descriptions, clinical findings, treatment and survival times in cats. Medical records of 45 cats with LGL lymphoma were retrospectively evaluated. The most common clinical signs were decreased appetite, anorexia, weight loss, lethargy, and vomiting. The mesenteric lymph nodes and small intestine were the most commonly affected organs. One complete response and six partial responses were noted in the 23 cats that received chemotherapy as their initial treatment. Median survival time for cats that were treated was 57 days. Based on these results, feline LGL lymphoma appears to be minimally responsive to chemotherapy and is associated with a grave prognosis.
>> Journal abstract

Related articles:
Roccabianca, P., W. Vernau, et al. (2006). "Feline large granular lymphocyte (LGL) lymphoma with secondary leukemia: primary intestinal origin with predominance of a CD3/CD8(alpha)(alpha) phenotype." Vet Pathol 43(1): 15-28.
>> PubMed abstract and free, full text article

More on cat health: Winn Feline Foundation Library

Krick, E. L., L. Little, et al. (2008). "Description of clinical and pathological findings, treatment and outcome of feline large granular lymphocyte lymphoma (1996-2004)." Veterinary and Comparative Oncology 6(2): 102-110.

Large granular lymphocytes (LGL) can be found in the blood of healthy animals and usually constitute 10% or less of total circulating lymphocytes. Large granular lymphosarcoma/leukemia is a neoplastic disease of lymphocytes rarely seen in cats and dogs and is a distinct variation of lymphoma. Limited information exists regarding pathological and immunohistochemical descriptions, clinical findings, treatment and survival times in cats. Medical records of 45 cats with LGL lymphoma were retrospectively evaluated. The most common clinical signs were decreased appetite, anorexia, weight loss, lethargy, and vomiting. The mesenteric lymph nodes and small intestine were the most commonly affected organs. One complete response and six partial responses were noted in the 23 cats that received chemotherapy as their initial treatment. Median survival time for cats that were treated was 57 days. Based on these results, feline LGL lymphoma appears to be minimally responsive to chemotherapy and is associated with a grave prognosis.
>> Journal abstract

Related articles:
Roccabianca, P., W. Vernau, et al. (2006). "Feline large granular lymphocyte (LGL) lymphoma with secondary leukemia: primary intestinal origin with predominance of a CD3/CD8(alpha)(alpha) phenotype." Vet Pathol 43(1): 15-28.
>> PubMed abstract and free, full text article

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Carbimazole for Feline Hyperthyroidism

Frenais, R., S. Burgaud, et al. (2008). "Pharmacokinetics of controlled-release carbimazole tablets support once daily dosing in cats." Journal of Veterinary Pharmacology and Therapeutics 31(3): 213-219.


Carbimazole is a common oral treatment for feline hyperthyroidism, although not in North America. Carbimazole is a prodrug, as it is converted to methimazole after metabolism. Methimazole reduces production of the thyroid hormones, T3 and T4. The pharmacokinetics of methimazole was investigated in healthy cats following oral administration of 15 mg of carbimazole as a newly available controlled-release tablet (Vidalta®, Intervet). Methimazole levels were sustained and without a peak when compared to dosing with conventional carbimazole tablets. Repeated oral dosing for 13 days did not lead to accumulation of methimazole in plasma. Absorption of carbimazole was improved when administered with food. The relative oral bioavailability of methimazole following administration of the controlled-release tablets was similar to that of a conventional release formulation (83 ± 21%). The pharmacokinetics of this controlled-release formulation of carbimazole supports its use as a once daily treatment (both as a starting dose and for maintenance therapy) for cats with hyperthyroidism.
>> PubMed abstract


Related articles:
Bucknell, D. G. (2000). "Feline hyperthyroidism: spectrum of clinical presentions and response to carbimazole therapy." Aust Vet J 78(7): 462-5.
Free, full text article


More on cat health: Winn Feline Foundation Library

Frenais, R., S. Burgaud, et al. (2008). "Pharmacokinetics of controlled-release carbimazole tablets support once daily dosing in cats." Journal of Veterinary Pharmacology and Therapeutics 31(3): 213-219.


Carbimazole is a common oral treatment for feline hyperthyroidism, although not in North America. Carbimazole is a prodrug, as it is converted to methimazole after metabolism. Methimazole reduces production of the thyroid hormones, T3 and T4. The pharmacokinetics of methimazole was investigated in healthy cats following oral administration of 15 mg of carbimazole as a newly available controlled-release tablet (Vidalta®, Intervet). Methimazole levels were sustained and without a peak when compared to dosing with conventional carbimazole tablets. Repeated oral dosing for 13 days did not lead to accumulation of methimazole in plasma. Absorption of carbimazole was improved when administered with food. The relative oral bioavailability of methimazole following administration of the controlled-release tablets was similar to that of a conventional release formulation (83 ± 21%). The pharmacokinetics of this controlled-release formulation of carbimazole supports its use as a once daily treatment (both as a starting dose and for maintenance therapy) for cats with hyperthyroidism.
>> PubMed abstract


Related articles:
Bucknell, D. G. (2000). "Feline hyperthyroidism: spectrum of clinical presentions and response to carbimazole therapy." Aust Vet J 78(7): 462-5.
Free, full text article


More on cat health: Winn Feline Foundation Library

Read More