Plasma oestrogen changes in adult male cats after orchiectomy, body-weight gain and low-dosage oestradiol administration

Effects of a high-protein, high-fiber diet rich in antioxidants and L-carnitine on body weight, body composition, metabolic status, and physical activity levels of cats after spay surgery

Spay and neuter surgeries are useful in controlling pet populations, but increase obesity risk due to increased appetite, decreased metabolic rate and decreased energy expenditure. Dietary management may help limit post-spay weight gain, but few research studies have been conducted in cats. Therefore, the objective of this study was to evaluate the effects of a high-protein, high-fiber diet (HPHF) compared to a moderate-protein, moderate-fiber diet (MPMF) in female cats following spay surgery. Twenty healthy female cats (9.5±0.1 mo) were used. After a 4-wk baseline phase with cats fed MPMF to maintain body weight (BW), 16 cats were spayed and allotted to MPMF (n=8) or HPHF (n=8), with the remaining cats being sham-operated and fed MPMF (n=4). Cats were fed to maintain BW for 12 wk, then allowed to eat up to twice that amount for another 12 wk. Daily food intake, twice weekly BW and twice weekly body condition scores (BCS) were assessed. Back fat thickness (BF) using ultrasound, body composition using dual-energy X-ray absorptiometry (DEXA), feline body mass index (fBMI), body fat percentage estimates using zoometry measurements, serum metabolites, and voluntary physical activity levels were measured prior to spay (wk 0) and every 6 wk post-spay. A treatment*time effect was observed for food intake (g/d), but not caloric intake (kcal ME/d). Caloric intake was affected by time and treatment, being reduced over the first 12 wk and reduced at higher amounts in HPHF and MPMF cats vs. sham cats. BW, BCS and body fat percentage were affected over time. Treatment*time effects were observed for blood urea nitrogen, alkaline phosphatase, and fructosamine, while blood triglycerides, total cholesterol, creatinine, total protein, phosphorus, and bicarbonate were affected by time. Physical activity was reduced over time. Our results demonstrate that spay surgery affects food intake, BW, metabolism, and physical activity of cats. Dietary intervention in this study, however, led to minor changes.

Prevalence, risk factors, and disease associations of overweight and obesity in cats that visited the Veterinary Medical Teaching Hospital at the University of California, Davis from January 2006 to December 2015

Overweight and obesity are commonly diagnosed in domestic cats, and undermine cats' quality of life directly or indirectly via various disease processes known to be associated with overweight and obesity. Epidemiological studies have reported varied overall prevalence among different feline populations, and commonly identified risk factors such as neutering. However, disease associations were not consistently reported. The status of feline overweight and obesity in a referral veterinary teaching hospital in the United States remains undefined as well. The present study used descriptive statistics and logistic regression models to analyze feline medical records obtained at the Veterinary Medical Teaching Hospital at the University of California, Davis from January 2006 to December 2015 and to characterize the prevalence of overweight and obesity, risk factors, and disease associations. In 9,062 feline records analyzed, the overall prevalence of overweight (17.2%; n = 1,560) and obesity (23.8%; n = 2,160) was 41.0%. Neutered, male, and crossbred cats that were in age groups between 3.0 and 14.9 years old and presented with disease processes in orthopedic, dentistry, and urinary categories were positively associated with overweight and obesity. Overweight and obesity are prevalent problems, which can benefit from continual veterinary education emphasizing its importance. Structured disease surveillance plans monitoring these associated factors also help guide further research and ideally can contribute to development of better prevention strategies for overweight and obesity.

Risk of obesity in the neutered cat

Surgical neutering is one of the most common procedures performed on pets in the USA among other countries. There are known effects of neutering on the physiology and behavior of the cat that predispose to obesity, which is the most significant sequela from a nutritional perspective. Increased food intake is the most likely factor influencing weight gain in the neutered cat. Proactively addressing these changes with nutritional management strategies can help prevent weight gain and associated negative consequences.

The impact of time of neutering on weight gain and energy intake in female kittens

Neutering is a risk factor for obesity in companion animals. In a study to determine the total energy requirements of kittens (15-52 weeks) the impact of neutering and age when neutered on intake and body weight (BW) was investigated. Females (n 14), neutered when 19 (early neuter; EN) or 31 (conventional neuter; CN) weeks old (n 7/group), were individually fed to maintain an ideal body condition score (BCS). EN kittens gained weight gradually whilst CN kittens' BW gain slowed from week 24, weighing less than EN kittens from week 30 with a reduced energy intake (kcal/kg BW^0·67) in weeks 24-32 (P < 0·05). Following neutering, CN cats' BW and energy intake increased rapidly (energy intake CN > EN in weeks 36-40). Although EN required earlier diet restriction, acute hyperphagia and increased rate of BW gain following neutering were not observed. Earlier neutering may aid healthy weight management through growth when regulating intake to maintain an ideal BCS.

Scope of the Problem and Perception by Owners and Veterinarians

Obesity is a common disease of modern dogs and cats. Dog and cat owners often do not realize their animal is affected. Some pet owners are skeptical of the diagnosis or rationalize the overweight condition of their pets. Animal-related factors associated with obesity in dogs and cats include breed, neuter status, age, and gender, whereas owner-related factors include diet choice, feeding method, and provision of exercise. Owner characteristics, such as age and income, are also potential risk factors for pet obesity. Identifying such risk factors for both animals and owners may help provide targets for prevention or interventional tools.

Short-Term Estrogen Replacement Effects on Insulin Sensitivity and Glucose Tolerance in At-Risk Cats for Feline Diabetes Mellitus

Male domestic cats that are neutered and overweight are at an increased risk for developing a type-2-like diabetes mellitus. Beneficial effects of 17β-estradiol (E2) on glucose homeostasis may be lost with neutering and thereby account for increased diabetes risk. To evaluate this, adult male neutered overweight cats (n=6) were given daily E2 (1.0 μg/kg) or vehicle (Vh; ethanol, 1.0μL/kg) in a single crossover trial of 14-day periods with a 7-day washout. The E2 and Vh were voluntarily ingested on food. The E2 dosage was determined in a pre-trial to significantly and transiently reduce food intake with no measurable change in plasma E2 concentration. During treatments, physical activity was assessed with collar-mounted accelerometers on days 9-11, and tests of intravenous insulin tolerance and intravenous glucose tolerance were conducted on days 13 and 14, respectively. Over the 14 days, E2 compared to Vh treatment reduced (p=0.03) food intake (- 22%) but not enough to significantly reduce body weight; activity counts were not significantly changed. With E2 compared to Vh treatment, the late-phase plasma insulin response of the glucose tolerance test was less (p=0.03) by 31%, while glucose tolerance and insulin sensitivity indexes were not significantly changed. The results indicate that oral E2 at a dosage that moderately affects food intake may reduce insulin requirement for achieving glucose homeostasis in neutered male cats. Further investigation is needed to identify the mechanism underlying the E2 effect.