Challenges in measuring energy expenditure in companion animals: a clinician's perspective

Validation of saliva and urine use and sampling time on the doubly labelled water method to measure energy expenditure, body composition and water turnover in male and female cats

Less invasive protocols are necessary to study energy expenditure (EE) of cats living in homes for expressing their normal living conditions. The present study compared sampling times and the use of saliva, urine and blood to measure 2H and 18O to apply the doubly labelled water method. In the first study, four cats were used to evaluate the enrichment (2, 4, 6, 7 and 8 h) and elimination (2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 d) of 2H and 18O (subcutaneously injected). The maximum enrichment was after 5 h (R2 0·82) of injection, with an Ln linear elimination of both isotopes (P < 0·001; R2 0·99). The results of EE were similar, regardless of the sampling time used (P = 0·999). In the second study, seven male cats and seven female cats were used. Before and after isotope injection (5 h, 7 d, 10 d and 14 d), blood, saliva and urine were collected. Isotope enrichment was lower in urine (P < 0·05) and at the similar level in blood and saliva. Isotope elimination was similar for all fluids (P < 0·473). The EE calculated with blood and saliva was similar but higher for urine (P = 0·015). According to Bland-Altman statistics, blood and saliva presented low bias and high correlation (P < 0·001), but this was not observed for urine (P = 0·096). Higher EE was observed for male cats (384 (se 39) kJ/kg0·67 per d) than for female cats (337 (se 34) kJ/kg0·67 per d; P < 0·05). The sampling time for the method is flexible, and saliva can be used as a substitute for blood.

Nutritional management of a kitten with thermal burns and septicaemia

Case summary

A 3-month-old entire female British Shorthair cat presented for further management of thermal burns after falling into a bath of scalding water. On presentation to the primary care clinician the kitten was obtunded, markedly painful and relatively bradycardic, consistent with a state of shock. The haircoat was wet, with erythematous skin and sloughing from the digital pads and anal mucosa. The primary care clinician administered opioid analgesia, sedation, antibiotics and started intravenous (IV) fluid therapy prior to referral. On arrival to the referral hospital the kitten was obtunded with respiratory and cardiovascular stability but was overtly painful and resistant to handling. The kitten required intensive management with IV and regional analgesia, IV broad-spectrum antibiosis, IV fluid therapy, enteral nutrition and wound management, including surgical debridement and topical antibiotic therapy. Septicaemia developed during the hospitalisation. Multidrug-resistant Escherichia coli and Pseudomonas aeruginosa were cultured, and antibiosis was escalated to IV imipenem. Acute respiratory distress syndrome was suspected following the development of dyspnoea. Early enteral nutrition within 24 h of admission was initiated using an oesophageal feeding tube and a veterinary therapeutic liquid diet. Over the ensuing 72 h the kitten started voluntary intake of food alongside oesophageal tube feeds. The kitten experienced continued weight loss despite the provision of nutritional support to meet, and then later exceed, the estimated resting energy requirements. Caloric intake was gradually increased to a total of 438% of the calculated resting energy requirement using the most recent daily body weight, eventually resulting in stabilisation of weight loss and weight gain.

Relevance and novel information

There is limited published information on the nutritional management of veterinary patients with thermal burn injury. Hypermetabolic states related to burn injuries are induced and maintained by complex interactions of catecholamines, stress hormones and inflammatory cytokines on proteolysis, lipolysis and glycogenolysis. Secondary infections are common following burn injury and the subsequent proinflammatory state perpetuates hypermetabolism and catabolism. These states present a challenge in both predicting and providing adequate nutrition, particularly in a paediatric septic patient. This subset of patients should be monitored closely during hospitalisation to ensure body weight and condition are maintained (while taking into consideration hydration status), and caloric intake is adjusted accordingly to meet nutritional support goals. Extensive research exists regarding the nutritional requirements and metabolic derangements of people with thermal burns. However, the importance of maintaining body weight and body condition in veterinary burn patients, and the association between nutritional support and reduced morbidity and mortality, has not been investigated and remains to be elucidated.

Predictive equations of maintenance energy requirement for healthy and chronically ill adult dogs

Maintenance energy requirement (MER) is the energy amount necessary for dogs to maintain their weight and body condition. Some factors can influence the MER, such as gender, age, neutering status and also diseases. The present retrospective study aimed to evaluate MER of adult dogs with several diseases and compare with the MER of healthy adult dogs, observing the influence of parameters such as body condition score (BCS), neutering status, gender, age, diagnosis and type of food on MER of these dogs. A total of 165 adult dogs with weight changes of ≤5% were included and divided in groups according to diagnosis. Mean MER for healthy dogs was 86.09 kcal/BW^0.75 , which differed from NRC and FEDIAF recommendations for inactive adult dogs (p = .047). Lowest MERs were of the endocrinopathies (78.52 ± 19.32 kcal/BW^0.75 ), orthopaedic diseases (59.71 ± 19.30 kcal/BW^0.75 ) and neurologic diseases (78.83 ± 32.66 kcal/BW^0.75 ) groups. Gastrointestinal diseases (99.59 ± 20.36 kcal/BW^0.75 ), orthopaedic diseases (59.71 ± 19.30 kcal/BW^0.75 ) and neoplasia (95.61 ± 21.02 kcal/BW^0.75 ) groups were the only groups that differed from the mean MER of healthy adult dogs. Regarding BCS, for each increasing point in a 9-point scale, there was a decrease of 9.8 kcal/BW^0.75 on MER, independent of diagnosis (p < .0001; r²  = .55). There was no difference regarding breed size gender and age, but neutered dogs presented lower MER (p = .031). Based on data obtained from the present study, it can be concluded that it is necessary to consider BCS, age, neutering status and diagnosis when calculating MER, both in healthy dogs and chronically ill dogs.

Tissue-specific expression and circulating concentrations of nesfatin-1 in domestic animals

Nesfatin-1 is a naturally occurring 82-amino acid protein encoded in the precursor nucleobindin-2 (NUCB2) and has been implicated in multiple physiological functions, including food intake and blood glucose regulation. This study aimed to characterize nesfatin-1 in domestic species, especially cats (Felis catus), dogs (Canis lupus familiaris), and pigs (Sus scrofa). Our in silico analysis demonstrated that the NUCB2/nesfatin-1 amino acid sequence, especially the bioactive core region of the peptide, is very highly conserved (more than 90% identity) in domestic animals. Expression of mRNAs encoding NUCB2/nesfatin-1 was detected in the cat, dog, and pig stomach and pancreas. Immunohistochemistry revealed the presence of nesfatin-1 in the gastric mucosa of the stomach of dogs, cats, and pigs, and in the pancreatic islet β-cells of dogs and pigs. No nesfatin-1 immunoreactivity was found in the cat pancreas. Nesfatin-1 was detected in the serum of dog, cat, pig, bison, cow, horse, sheep, and chicken. Circulating nesfatin-1 in male and female dogs remained unchanged at 60 min after glucose administration, suggesting a lack of meal responsiveness in nesfatin-1 secretion in this species. The presence of nesfatin-1 in the gastric and endocrine pancreatic tissues suggests possible roles for this peptide in the metabolism of domestic animals. Future research should focus on elucidating the species-specific functions and mechanisms of action of nesfatin-1 in health and disease of domestic animals.

Inaccurate Assessment of Canine Body Condition Score, Bodyweight, and Pet Food Labels: A Potential Cause of Inaccurate Feeding

The objectives were to investigate owners’ ability to assign the correct bodyweight (BW) and body condition score (BCS) to their dog and to interpret wet and dry pet food labels by estimating how much to feed daily. One hundred and seventy-four questionnaires were completed. Owner estimated BW was compared to actual BW, correct being defined within ±10% of actual BW. Correct interpretation of the total amount of food required was determined by the number of cans (±25% of cans) required for wet food and grams (±20% of grams) for dry food, based on the dog’s actual BW, the feeding guidelines on the label, and a comparison with the owner’s estimate. Eleven percent of owners overestimated BCS and 19% overestimated BW. Only 48% of owners could correctly estimate their dog’s BW. Only 23% and 43% of owners could correctly estimate how much wet and dry food to feed, respectively. Chi-square analysis demonstrated a significant positive association for owners correctly estimating their dog’s BW and interpreting the wet pet food label. Many owners are not aware of their pet’s BCS and BW and cannot accurately interpret pet food labels. Further owner education to improve these skills is needed if dogs are to be fed correctly.

Canine and feline obesity: a review of pathophysiology, epidemiology, and clinical management

Canine and feline obesity rates have reached pandemic proportions and are similar to those in humans, with approximately 30%-40% of dogs and cats being overweight to obese. Obesity has been associated with other health problems, including osteoarthritis, renal disease, skin disease, insulin resistance, and neoplasia in dogs, while in cats obesity is associated with dermatological issues, diabetes mellitus, neoplasia, and urolithiasis. The health issues appear to be slightly different across the two species, which may be due to some inherent differences in the hormonal milieu involved in obesity that differs between the dog and the cat. In this review, we discuss the complicated nature of the pathogenesis of obesity, the hormonal stimulus for orexigenic and anorexigenic behavior, adipose tissue as an endocrine organ, and most importantly, clinical management of the number one disease in canine and feline medicine.

Energy requirements of adult dogs: a meta-analysis

A meta-analysis was conducted to determine the maintenance energy requirements of adult dogs. Suitable publications were first identified, and then used to generate relationships amongst energy requirements, husbandry, activity level, methodology, sex, neuter status, dog size, and age in healthy adult dogs. Allometric equations for maintenance energy requirements were determined using log-log linear regression. So that the resulting equations could readily be compared with equations reported by the National Research Council, maintenance energy requirements in the current study were determined in kcal/kg(0.75) body weight (BW). Ultimately, the data of 70 treatment groups from 29 publications were used, and mean (± standard deviation) maintenance energy requirements were 142.8±55.3 kcal·kgBW(-0.75)·day(-1). The corresponding allometric equation was 81.5 kcal·kgBW(-0.9)·day(-1) (adjusted R2 = 0.64; 70 treatment groups). Type of husbandry had a significant effect on maintenance energy requirements (P<0.001): requirements were greatest in racing dogs, followed by working dogs and hunting dogs, whilst the energy requirements of pet dogs and kennel dogs were least. Maintenance energy requirements were less in neutered compared with sexually intact dogs (P<0.001), but there was no effect of sex. Further, reported activity level tended to effect the maintenance energy requirement of the dog (P = 0.09). This review suggests that estimating maintenance energy requirements based on BW alone may not be accurate, but that predictions that factor in husbandry, neuter status and, possibly, activity level might be superior. Additionally, more information on the nutrient requirements of older dogs, and those at the extremes of body size (i.e. giant and toy breeds) is needed.

Energy requirements of adult cats

A meta-analysis was carried out in order to establish the energy requirements of adult cats. Publications that identified cat body weight (BW) were used to generate allometric relationships between energy requirements and BW of healthy adult cats, using log-log linear regression. Energy requirements were expressed in kcal/kg BW to be consistent with those reported by the National Research Council. Mean maintenance energy requirements were 55·1 (se 1·2) kcal/kg BW (115 treatment groups). Three allometric equations were identified to predict the energy requirements for maintenance of BW in the cat based on BW: light (53·7 kcal/kg BW− 1·061), normal (46·8 kcal/kg BW− 1·115) and heavy (131·8 kcal/kg BW− 0 ·366). When reported on lean mass, the allometric equation revealed maintenance requirements were 58·4 kcal/kg lean mass− 1·140 (adjusted R2 0·694; thirty-six treatment groups). The present review suggests that values for maintenance energy requirements based on BW alone may not be an accurate prediction and more detailed information on the age, sex and neuter status, BW and composition would enhance the ability to interpret the maintenance energy requirements of cats.