Behavior in dogs with spontaneous hypothyroidism during treatment with levothyroxine

Abstract

BackgroundThyroid hormone supplementation anecdotally has been described as a valid treatment option for dogs with aggression‐related problems. However, prospective, controlled, and blinded trials evaluating behavior and neurohormonal status in hypothyroid dogs during treatment with levothyroxine are lacking.ObjectiveLevothyroxine supplementation will have a significant influence on the behavior and neurohormonal status of dogs with spontaneous hypothyroidism.AnimalsTwenty client‐owned dogs diagnosed with spontaneous hypothyroidism.MethodsThis prospective study was to evaluate the behavior of dogs, which was screened at initial presentation, and after 6 weeks, and 6 months of treatment with levothyroxine (starting dosage 10 μg/kg PO q12h) using the standardized Canine Behavioral Assessment and Research Questionnaire (C‐BARQ). At each time period, circulating serotonin and prolactin (PRL) concentrations were evaluated using a commercially validated ELISA kit and heterologous radioimmunoassay, respectively.ResultsAfter 6 weeks of thyroid hormone supplementation, C‐BARQ scores demonstrated a significant increase in activity of hypothyroid dogs (P < .01). No significant change in any of the behavioral signs was observed after 6 months of treatment. No significant difference in circulating concentrations of serotonin (P > .99 and P = .46) and PRL (P = .99 and P = .37) were noted between the 6‐week and 6‐month periods compared with baseline.Conclusions and Clinical ImportanceThe results of this study indicate increased activity of hypothyroid dogs after 6 weeks of thyroid hormone supplementation. None of the hypothyroid dogs in this cohort showed a significant change in any of the evaluated behavioral signs and neurohormonal status after 6 months of thyroid hormone supplementation.

Making the Case for Multi-Axis Assessment of Behavioural Problems

“…In a randomised, double-blinded, placebo-controlled study of the effect of thyroid replacement therapy on aggressive dogs (owner-directed) with suboptimal thyroid function, Dodman et al did not find an effect [37]. Hrovat et al tracked behavioural changes during levothyroxine therapy over six months in clinically hypothyroid dogs using the C-BARQ questionnaire, and found no change other than an increase in the score for the activity sub-scale [38]. Taken as a whole, this suggests that, as in human medicine, clinical hypothyroidism may be associated with behavioural pathology in individual cases, but that thyroid function does not have a generalised effect on aggression.…”

Clinical Signs and Behavior in Dogs with Hypothyroidism

“…Recent research has dispelled the belief that hypothyroidism is associated with aggressive behavior in dogs and instead suggested an increase in activity as the most characteristic symptom (12,13). This study also signified that hypothyroidism in dogs is not associated with aggressive behavior but is associated with frequent attention-seeking and excitation.…”

“…In addition to the diagnostic challenges, dogs diagnosed with hypothyroidism have been observed to experience changes in their behavior. While some authors have asserted that dogs with hypothyroidism may exhibit signs of aggression (9,10,11), others have found no connections between this behavior and hypothyroidism (12,13). The thyroid hormone is known to encourage neuroprotection and control neurogenesis (14).…”