Experimental Obesity in the Dog

Abstract

During the past 5 years obesity in dogs frequently has been observed following operations on the hypophysis and hypothalamus. The operations, performed mostly through the oral approach, involved: (1) removal of the posterior lobe with or without removal of the pars distalis: (2) section of the fibers to the neurohypophysis with the immediate or subsequent removal of the adenohypophysis, the infundibular stem and the infundibular process; (3) removal of the neuro and adeno hypophysis at one sitting; (4) median transverse section of the posterior hypothalamus between the infundibular stem and mammillary bodies with or without removal of the posterior lobe and the pars distalis. The conclusions reported in this paper are based on observations made on 125 animals with a fairly equal distribution among the above classes.

The animals were kept in metabolism cages and 24-hour urine collections were made. They were fed measured limited amounts of dog chow and horse meat except when for experimental purposes unlimited but measured quantities were allowed. The dogs were kept for a period before operation to establish a constant weight and to determine the normal daily urine output. They then were subjected to operation and kept for periods of observation varying from 3 months to over a year. All but 6 of the animals have been sacrificed to obtain anatomical material to determine the lesions present in the hypophysis and in the hypothalamus. The brains were fixed in situ by irrigation through the carotid artery with formalin 1 to 10 after bleeding the animal. After further fixation the sella and its contents were separated from the hypothalamus.