Safety of orally administered, USP-compliant levothyroxine sodium tablets in dogs

Wellbeing, quality of life, presence of concurrent diseases, and survival times in untreated and treated German Shepherd dogs with dwarfism

BACKGROUND

Pituitary dwarfism (PD) in German Shepherd dogs (GSD) is a rare endocrinopathy. Cause and inheritance of the disease are well characterized, but the overall survival time, presence of concurrent diseases, quality of life (QoL) and influence of different treatment options on those parameters is still not well investigated. The aim of this study was to obtain data regarding the disease pattern of GSD with PD and to investigate the impact of treatment.

METHODS

47 dogs with dwarfism (presumably PD) and 94 unaffected GSD serving as controls were enrolled. Data were collected via a standardized questionnaire, which every owner of a participating dog had completed. Dogs with PD were grouped based on three categories of treatment: Group 1 (untreated), group 2 (treated with levothyroxine), group 3 (treated with thyroxine and progestogens or with growth hormone (GH)). Groups were compared using One-Way-Anova, Kruskal-Wallis test or Wilcoxon-rank-sum test. Categorical analysis was performed using Two-Sample-Chi-Squared-test.

RESULTS

Dogs treated with thyroxine and gestagen or GH were significantly taller and heavier compared to all other dogs with PD. Quality of life was best in dogs with PD treated with thyroxine and similar to unaffected GSD. Treatment increased survival time in dogs with PD independent of the treatment strategy. Dogs receiving thyroxine and progestogens or GH did not develop chronic kidney disease (CKD).

CONCLUSION

GSD with PD should be treated at least for their secondary hypothyroidism to increase survival time. Additional treatment with progestogens or GH improves body size and seems to protect against the occurrence of CKD.

A Pivotal Field Study to Support the Registration of Levothyroxine Sodium Tablets for Canine Hypothyroidism

A prospective, pivotal, multicenter field study to evaluate the dose regimen, effectiveness, and safety of levothyroxine sodium tablets, USP for the treatment of hypothyroidism and hypothyroidism-associated clinical signs in dogs was conducted. Ninety-two dogs diagnosed with primary hypothyroidism met the entrance criteria and were enrolled into the study. Levothyroxine sodium was administered to each dog on a daily basis either as the whole dose q 24 hr or as half the dose q 12 hr. Dosing started at 0.1 mg/10 lb (0.022 mg/kg) and continued for approximately 6 mo to Day 182. During this time, the thyroid status of each dog was evaluated at monthly intervals. For the determination of effectiveness, dogs classified as euthyroid at Day 182, based on their thyroid hormone values, were considered treatment successes. Results of the statistical analysis showed that there was no difference between the two dosing regimens (P = .11) and that when the data from both groups were pooled, the overall success rate was 75.64% (95% confidence interval = 66.34%). By Day 182, improvement and/or resolution of hypothyroidism-associated clinical signs was observed in all categories. No abnormal trends in the reported adverse events were observed.