Thyroidectomy produces abnormal grooming behavior in cats

Abstract

Cats with midbrain lesions exhibit an abnormal dissociation between appetitive and consummatory grooming behaviors and some signs of hypothyroidism. To determine jf a hypothyroid state causes the abnormal dissociation, six cats were thyroidectomized and their behavior monitored. The thyroidectomized cats exhibited the same abnormal dissociation in grooming behavior as did the cats with midbrain lesions. However, certain considerations, including the latency and time course of the thyroidectomized-induced changes, suggest that the hypothyroid state is not directly involved, but rather brings about other endocrine and metabolic changes that are involved in the production of the behavioral abnormality.Ouring a study of abnormal grooming behaviors that were induced by lesions of the caudal midbrain region, histological signs of thyroid dysfunction were found (RandalI, 1964). Subsequent investigations revealed that the grooming abnormality waxed and waned concomitantly with rhythmic fluctuations in thyroid activity (Randali & Littschwager, 1967). The grooming a bnormalities occur most frequently in the fall of the year, a time when the normal maximum in thyroid activity occurs. Ouring the spring, a time of the normal troughs in thyroid activity, the cats with brain-stem lesions are normal, exhibiting none of the abnormal behavior that was present in the fall.The abnormal grooming behavior, which appears after brain-stem lesions, consists of a dissociation between appetitive and consummatory grooming behaviors. The dissociation is detected by directing light tactile stimuli to the body surface of the ca!. These light tactile stimuli, which have no effect on the normal cat, elicit three consummatory grooming behaviors. The particular consummatory behavior that is elicited depends on the part of the body surface that receives the tactile stimuli: Touth the head or neck or shoulder of the cat and a nonoriented nonfunctional scratching movement of the foot is elicited; stroke the lateral surface of the trunk and the tongue is protruded and a lick occurs; touch the dorsal surface of the body and a nondirected grooming bite occurs in midair. These three consummatory behaviors occur in normal cats at the end of orienting behaviors but are elicited in lesioned cats by tactile stimuli without the normally preceding appetitive components.

Role of thyroid hormones in an abnormal grooming behavior in thyroidectomized cats and cats with pontile lesions.

“…ectomized cats exhibited the identical disintegration of appetitive and consummatory grooming behavior as did the cats with pontile lesions (Randall & Parsons, 1970). However, certain features of the time course and latency of the behavioral changes following thyroidectomy precluded the simple interpretation that the behavioral abnormality in the cats with pontile lesions was attributable merely to a hypothyroid state; e.g., the onset of the abnormal behavior occurred months after thyroidectomy, and the abnormal behavior of both the thyroidectomized cats and the cats with pontile lesions exhibited the same rhythmic variations during the year (Randall & Parsons, 1970).…”

“…Five thyroidectomized cats and 14 cats with pontile lesions were used in the first study. A preliminary report of this first study has been published (Randall & Parsons, 1970).…”