Special Feeding and Care of Senescent Spontaneously Hypertensive Rats.

This study investigated the impact of feeding methods on body weight of senescent female spontaneously hypertensive rats (SHRs) and showed that supplementing powdered feed was useful as they approached heart failure at 22 to 23 months of age. SHRs are genetically predisposed to systemic hypertension and will, with age, progress into complete heart failure resulting in death. Close to the time of heart failure, some rats experienced a loss of appetite and weight loss. It was postulated that either elevated blood pressure, age-associated health issues, or the effort required to access pelleted food prevented the rats from eating properly, resulting in malnutrition and weight loss. As they aged, the rats benefited from the addition of powdered food to ensure that body weights remained stable and to prevent malnutrition that could lead to premature death. Animals were fed commercially available rat chow pellets until they showed persistent signs of weight loss or a lack of interest in their food. At that time, the rats were also given powdered rat chow in shallow bowls to facilitate the eating and the digestion of their food. The rats were weighed weekly to confirm they consumed sufficient calories daily and to ensure that the change to the powdered chow was having the desired effect. Prior to being fed the powdered rat chow, the rats had shown signs of progressive weight loss. After starting the powdered chow, the rats either maintained or gained weight. This study shows that as the female SHR matures, special care and handling is key to maintaining body weights and good health. With only modest changes in routine (i.e., powdered food) and an attentive eye on the rats' daily activities, it was possible to maintain these senescent female SHRs in a healthy condition until the termination of the study or onset of heart failure.