Neutering is often associated with obesity in companion animals. However, the maintenance energy requirement (MER) for these animals has not been clearly defined. The present study investigated the MER for spayed cats whose body weights (BW) began to increase shortly after ovariohysterectomy. A total of twenty-two shorthair adult female cats were fed complete and balanced diets in amounts to maintain their BW and body condition score (BCS) before the present study. All cats were spayed and the diet was fed for 11 weeks using the same MER as previously. During these weeks, all cats gained weight. Beginning with week 12, a weight-loss regimen was initiated until each cat achieved a BCS of 5 out of 9. After each cat obtained a BCS of 5, an appropriate amount of diet was fed to maintain its BW for at least 4 weeks to determine a modified MER. Daily food consumption, weekly BW and BCS were monitored. Blood was collected before and after weight loss for plasma biochemistry profiles. BW and BCS increased by 16 % and one point (P,0·01), respectively, during the first 11 weeks after surgery, although food consumption was constant both pre-and post-surgery. The mean MER after obtaining a BCS of 5 was 313·6 (SEM 23·6) kJ/BW 0·67 , which is 25 % lower than the current National Research Council recommendation and lower than the cat's requirement before surgery (P, 0·05). In conclusion, spaying significantly increased BW when using MER values for intact cats. Thus, 313·6 £ ideal BW 0·67 kJ is proposed for the MER of spayed adult cats.

In this study, we investigated a combination of a low glycemic index starch (LGIS) and diacylglycerol (DAG) on lipid, lipoprotein (LP) metabolism, and weight management. Obese, intact female adult Beagle dogs were assigned to 1 of 4 starch/oil combination diets [LGIS/DAG (LD); LGIS/triacylglycerol (TAG); high glycemic index starch (HGIS)/DAG; and HGIS/TAG (HT)] and fed for 9 wk (n = 6/group) using an incomplete 4 × 4 Latin square design. Each dog was fed 1 of 2 opposite starch/oil combination diets (e.g. LD and HT). At wk 1 and 8, postprandial blood was collected for plasma triacylglycerol (TG), β-hydroxybutyrate (BHB), total cholesterol (TC), and LP analyses. During the same week, dogs were overnight feed-deprived and post-heparin blood was collected for LP lipase and hepatic lipase activity determinations. At wk 1, 4, and 8, blood was drawn from overnight feed-deprived dogs for plasma TG, BHB, TC, LP, leptin, and adiponectin measurements. Feces were collected at wk 3 for digestibility calculations. The LGIS diets resulted in lower carbohydrate, protein, total tract dry matter digestibilities, and metabolizable energy compared with the HGIS diet groups (P < 0.05). Thus, the LGIS groups lost more body weight (P = 0.001), which was positively correlated with plasma leptin concentrations (r(2) = 0.427; P < 0.001). Moreover, the LGIS diet lowered TC concentrations in combination with DAG. The DAG diet groups decreased postprandial TG and increased BHB concentrations (P < 0.05). Starch/oil types did not alter lipase activities or adiponectin concentrations. In conclusion, the LGIS diet demonstrated potential as a weight management tool in dogs by decreasing postprandial TG and increasing BHB in combination with DAG.

For the purpose of investigating the mechanism of obesity-induction/re-induction including weight-cycling in beagles, a study was conducted using commercially available dog food combined with human food to mimic at home-snacking and diet-supplementation behaviours. Adult female beagles, which had free access to water and exercise, were used (n = 9). All dogs were initially offered two times their daily calculated number of calories using a dry extruded diet plus blend of canola and soybean oils and allowed to eat ad libitum. After 3 weeks, Pecan shortbread cookies were added to the diet mixture. Obesity was induced during a 19-week period with 1875-2250 kcal/day consumed, on average, during this period. The dogs were then subjected to a weight-loss regimen while consuming 490-730 kcal/day. After weight loss, a similar degree of obesity was re-induced for 17 weeks even though dogs consumed only 1125-1250 kcal/day. Body weight, body condition scores, kcal consumption and food efficiency were recorded. Results indicated that less time and fewer kcal were required to re-induce the same degree of obesity compared with the initial obesity induction. Human snack foods appeared to stimulate appetite and thus contribute to the obese state. Food efficiency was also increased during the obesity-reinduction period compared with the induction period. This information may help pet owners better understand the need to limit table scraps and human-type food snacks in dogs prone to obesity as well as weight maintenance after weight loss.

The relationship between lecithin:cholesterol acyltransferase (LCAT) activity and weight loss in dogs was investigated. Four experimental weight-loss diets were fed to 12 obese female beagles for 56 days in a partial crossover design (n = 6). High- (HGI) or low- (LGI) glycemic index starch and diacylglycerol or triacylglycerol oils were combined to compose experimental diets with similar fatty acid profiles. Food intake and body weights were measured daily and weekly, respectively. Fasted blood samples were drawn at day 0, day 28, and day 56 to measure plasma LCAT activity and total (TC), unesterified (UC), and esterified (EC) cholesterol concentrations, and for fatty acid analysis of the phospholipid (PL) and EC fractions. The LGI groups lost more weight than the HGI groups due to starch digestibility differences. An HGI starch effect on TC and UC concentrations was observed but was unrelated to weight loss. LCAT activities increased over time but were not different after controlling for percentage weight loss. However, a positive linear correlation was found between LCAT and UC concentrations in all groups. Plasma PL fatty acid profiles reflected the diets fed, but increases in 16 and 18 carbon saturated and monounsaturated fatty acids in all groups appeared to be an effect of fatty acid mobilization from storage sites. Both plasma PL and EC fatty acid profiles were similar with both acylglycerol types and EC fatty acids reflected linoleic acid specificity with minimal diet or time effects.

Obesity increases insulin resistance and disregulation of glucose homeostasis. This study investigated low glycemic index starch (LGIS)/diacylglycerol (DAG) diet on plasma insulin and circulating incretin hormones during canine weight loss. Obese Beagle dogs were fed one of four starch/oil combination diets (LGIS/DAG; LGIS/triacylglycerol (TAG); high glycemic index starch (HGIS)/DAG; and HGIS/TAG) for 9 weeks during the weight loss period. At weeks 1 and 8, fasting plasma insulin, glucose, nonesterified fatty acid (NEFA), glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-1 (GLP-1) were determined. Weight loss did not affect fasting insulin, glucose, and NEFA, but fasting GIP increased and GLP-1 decreased. LGIS affected postprandial insulin at both times and glucose was similar to insulin, except 60 min postprandially with DAG at week 8. NEFA lowering was less with the LGIS diets initially but not thereafter. At 60 min postprandially on week 8, GIP was significantly elevated by DAG, while GLP-1 was increased only with the HD diet. LGIS suppressed insulin and glucose responses up to 180 min postprandially at both sample times. DAG increased incretin hormones as did the DAG/HGIS combination but only at week 8. This latter finding appeared to be related to the glucose response but not to insulin at 60 min.