Nutrition and Aging in Dogs and Cats.

Aging is often associated with chronic inflammation and declining health. Both veterinarians and owners of aging dogs and cats are interested in nutritional solutions and strategies to prevent signs of age-related disease, increase longevity, and improve quality of life. Physiological decreases in muscle mass, decreased immunity, and a decrease in sense acuity are some of the changes often seen in otherwise healthy senior pets; however, there may also be an increase in risk for pathologies such as renal, cardiovascular, musculoskeletal, and neoplastic diseases. Aging may also lead to cognitive decline and even cognitive dysfunction. Some nutritional strategies that may be helpful with the prevention and treatment of age-related diseases include supplementation with ω3 polyunsaturated fatty acids and antioxidant nutrients that can help modulate inflammation and benefit osteoarthritis, renal disease, cancer, and more. Supplementation with medium-chain triglycerides shows promise in the treatment of canine cognitive dysfunction as these may be metabolized to ketone bodies that are utilized as an alternative energy source for the central nervous system. Additionally, a high intake of dietary phosphorus in soluble and bioavailable forms can lead to renal disease, which is of greater concern in senior pets. There are no published guidelines for nutritional requirements specific to senior pets and as a result, products marketed for senior dogs and cats are highly variable.

Evaluation of iron, copper and zinc concentrations in commercial foods formulated for healthy cats.

OBJECTIVES: The aim of this study was to analyze iron, copper and zinc concentrations in commercial foods and compare among food formats (dry, canned, raw), foods marketed by age category (adult 1+ years and senior 7+ years) and foods intended for adult maintenance vs all life stages. METHODS: In total, 112 commercial non-therapeutic food products marketed for healthy adult and senior cats were purchased in the USA. Foods were analyzed for their proximate composition. Trace mineral concentrations were measured using inductively coupled argon plasma-optical emission spectroscopy and described on a calculated metabolizable energy basis using standard modified Atwater values. RESULTS: Measured iron (median 58.4 mg/1000 kcal [range 15.7-379.0]), copper (median 5.6 mg/1000 kcal [range 0.8-13.3]) and zinc (median 47.6 mg/1000 kcal [range 7.6-128.1]) concentrations were highly variable among cat foods. When all food products - regardless of their nutritional adequacy substantiation method - were compared with the Association of American Feed Control Officials regulatory minimums, 13/112 food products had a mineral deficiency, of which a majority (n = 11/13) were raw food products. Raw foods had significantly lower trace mineral concentrations compared with dry food products and, except for copper, canned food products. Cat foods marketed for senior cats had higher iron (P = 0.019) and zinc (P <0.0001) concentrations than foods marketed for adult cats. Foods intended for adult maintenance had higher iron (P = 0.003) and zinc concentrations than foods intended for all life stages (P <0.0001). CONCLUSIONS AND RELEVANCE: Iron, copper and zinc concentrations in commercial non-therapeutic foods for adult and senior cats are highly variable. A minority of foods - mainly raw food products - were deficient in these minerals. It is unknown if some foods with high trace mineral concentrations could have adverse effects as studies are needed to establish safe upper limits for dietary intake of trace minerals in healthy cats.

Healthy Ageing Is Associated with Preserved or Enhanced Nutrient and Mineral Apparent Digestibility in Dogs and Cats Fed Commercially Relevant Extruded Diets.

Age-related changes in gastrointestinal function have been reported in companion animals, but the impact on digestive efficiency remains uncertain. Healthy dogs (n = 37; 2.6-14.2 years) received four diets varying in total dietary fibre (TDF; 6-29%, as fed). Healthy cats (n = 28; 1-13 years) received four diets with two fat (10-12%; 17-18%) and TDF (9 and 12%) levels. In a crossover design, diets were provided over four consecutive 10-day cycles, including a 4-day faecal collection. Apparent crude protein (CP), ether extract (EE), TDF, calcium (Ca), and phosphorus (P) digestibilities were determined. The effect of age was analysed as a continuous variable in dogs and as differences between adult (1-5 years) and senior (7-13 years) cats. In dogs, EE digestibility was unaffected by age (p > 0.10). Dogs of 6-12 years had higher digestibility of CP (p = 0.032), TDF (p = 0.019), Ca (p = 0.019), and P (p = 0.024) when fed the 6% TDF diet. Senior cats had greater digestibility of TDF (p < 0.01) and Ca (p = 0.024) but had lower EE and CP digestibility with one diet (17% fat; 9%TDF) (age, p > 0.10; diet × age, p < 0.001). Healthy ageing was associated with preserved nutrient digestibility in dogs and cats within the age ranges studied. The effect of ingredient sources in senior cats warrants further investigation.

No Observed Adverse Effects on Health Were Detected in Adult Beagle Dogs When Fed a High-Calcium Diet for 40 Weeks.

The implications of long-term high calcium (Ca) intake are well documented in growing dogs and in adult dogs of large breed size, however, the consequences on other breeds and breed sizes are yet to be determined. Eighteen neutered adult beagles, nine males and nine females aged 1.4-4.4 years, were randomized to control or test diets providing in g∙4184 kJ-1 (1000 kcal-1): 1.44 and 7.19 total Ca balanced with 1.05 and 4.25 total phosphorus, respectively, for 40 weeks. Health parameters, ultrasound scans, radiographs, glomerular filtration rate, and mineral balance were measured at eight-week intervals. All dogs remained healthy with no measured evidence of orthopedic, urinary, or renal disease. The test diet resulted in a 5.2 fold increase in fecal Ca excretion. Apparent Ca digestibility (%) and Ca balance (g/d) did not significantly (p > 0.05) change from baseline in the test diet group, although dogs displayed a positive Ca balance (maximum at week 8, 1.11 g/d with 95% CI (0.41, 1.80)) before a neutral Ca balance was restored at week 32. Despite an initial positive Ca balance, we can conclude that no measurable adverse health effects were observed as a result of the test diet fed in this study in beagles over a period of 40 weeks.

Calcium, Phosphorus, and Vitamin D in Dogs and Cats: Beyond the Bones.

Calcium, phosphorus, and vitamin D are nutrients that play a key role in maintaining normal organ, cell, and tissue function. Much is known about their role in bone metabolism, but these nutrients are also important in renal health, urinary tract disease, and multiple other organ systems. It is nutritionally important to meet the physiologic requirements for each of these nutrients, but the interplay between them should also be considered.

Evaluation of nutrient content and caloric density in commercially available foods formulated for senior cats.

BACKGROUND: Cat foods marketed for senior cats (≥7 years) are available to owners. The variability in the nutritional content of these foods is unknown. OBJECTIVES: To measure the caloric density and caloric distribution of crude protein, crude fiber, crude fat, phosphorus, calcium, magnesium, sodium, potassium, and vitamin D3 in commercially available foods for senior cats and to compare nutrient content with foods for adult cats. SAMPLES: Thirty-one senior and 59 adult commercial nontherapeutic cat food products. METHODS: Descriptive study. Crude protein, crude fiber, and crude fat were measured using Dumas nitrogen combustion, Ankom filter bag technique, and acid hydrolysis, respectively. Mineral concentrations were measured using inductively coupled argon plasma-optical emission spectroscopy. Vitamin D3 was determined by liquid chromatography with tandem mass spectrometry. Caloric density was calculated using modified Atwater values. RESULTS: The evaluated nutrient concentrations in all foods for senior cats met the values of the Association of American Feed Control Officials Cat Food Nutrient Profile for adult maintenance. Foods for senior cats had significantly higher crude fiber content when compared to foods for adult cats (P < .0001). No significant difference in crude protein, crude fat and mineral concentrations was found between foods for senior and adult cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Foods marketed for senior cats are highly variable in their caloric density and nutrient content and, except for crude fiber, are similar to foods for adult cats. Veterinarians should avoid broad recommendations regarding commercially available foods for senior cats, and dietary recommendations should reflect the patient's individual needs.

Evaluation of phosphorus, calcium, and magnesium content in commercially available foods formulated for healthy cats.

BACKGROUND: High dietary phosphorus (P) and low calcium-to-phosphorus ratio (Ca:P) are associated with kidney damage in cats. There are no established guidelines for dietary P maximum for cats. OBJECTIVES: To quantify crude protein, P, Ca, and magnesium (Mg) concentrations in cat foods and compare among food formats (dry, canned, raw), primary protein ingredients, protein concentrations (low, moderate, high), grain-free versus grain-containing foods, foods intended for adult maintenance versus all life stages, and cost. SAMPLES: Eighty-two commercial nonprescription cat foods. METHODS: Descriptive study. Mineral concentrations were measured using inductively coupled argon plasma-optical emission spectroscopy. Crude protein was measured using the Dumas nitrogen combustion method. Mineral and crude protein concentrations were compared among food categories. RESULTS: Twenty-seven foods contained ≥3.6 g P/1000 kcal metabolizable energy (ME), of which 7 exceeded 4.8 g/1000 kcal ME. Thirteen foods had low Ca:P ratio (≤1.0). The low-protein diet group had no products ≥3.6 g P/1000 kcal ME, which was significantly different compared to the high-protein diet group (52% of products had ≥3.6 g P/1000 kcal ME; P = .01). No significant differences in P content and Ca:P ratio were found among other diet categories. Canned foods had significantly lower Mg compared to dry (P < .001) and raw (P = .007) foods. Declared minimum P and Ca were significantly lower than analyzed concentrations (P = .0005 and P = .003, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: The high number of foods with high P and low Ca suggest that pet food regulatory reform should be considered.

Preliminary evaluation of fecal fatty acid concentrations in cats with chronic kidney disease and correlation with indoxyl sulfate and p-cresol sulfate.

BACKGROUND: Straight- and branched-chain (BCFA) short-chain fatty acids (SCFAs) are produced by colonic microbiota and have both beneficial and deleterious effects in humans with chronic kidney disease (CKD). Fecal SCFAs in cats with CKD have not been described. OBJECTIVE: To characterize fecal SCFA concentrations in cats with CKD as compared to healthy geriatric cats and correlate SCFA to serum indoxyl sulfate (IS) and p-cresol sulfate (pCS) concentrations. ANIMALS: Twenty-eight cats with CKD (International Renal Interest Society [IRIS] stages 2, 3, and 4) and 11 older (≥ 8 years) healthy geriatric cats. METHODS: Prospective, cross-sectional study. Voided feces were analyzed using stable isotope dilution gas chromatography-mass spectrometry to determine fecal concentrations of SCFAs. Serum concentrations of IS and pCS were measured using liquid chromatography tandem mass spectrometry. RESULTS: Fecal isovaleric acid concentrations were significantly higher in CKD cats(P = .02) Cats with IRIS CKD stage 3 and 4 had significantly higher fecal isovaleric acid concentrations compared to healthy geriatric cats (P = .03), but not compared to IRIS CKD stage 2 cats. Total fecal concentrations of BCFAs were found to correlate weakly with serum creatinine concentration (rho, 0.33; P = .05), blood urea nitrogen concentration (rho, 0.40; P = .01), and pCS concentration (rho, 0.35; P = .04). CONCLUSIONS AND CLINICAL IMPORTANCE: Fecal isovaleric acid concentrations were higher in CKD cats, particularly in late stage disease, compared to healthy geriatric cats. Fecal BCFA concentrations correlated with pCS and were higher in cats with muscle wasting, providing evidence for malassimilation of protein in CKD cats.

Metabolomic profiling to identify effects of dietary calcium reveal the influence of the individual and postprandial dynamics on the canine plasma metabolome.

Short-term feeding studies have highlighted a phenomenon in Ca regulation that raises concerns around Ca absorption in dogs that may make an impact on commercial diets near to the maximum recommended level. A recent study to determine responses in dogs fed one of two diets differing in dietary Ca over 40 weeks found no evidence to suggest a concern across a range of biological parameters hypothesised to be affected by Ca. Unforeseen consequences of dietary Ca could have occurred and metabolic profiling was deemed a suitable data-driven approach to identify effects of dietary Ca. The objectives were to compare the fasted plasma metabolome (sampled at 8-week intervals over 40 weeks) of dogs fed one of two diets, near to the minimum and maximum recommended levels of dietary Ca. Comparisons with the control diet were also investigated across the postprandial time course (1-4 h) following acute (1 d) and long-term (24 weeks) feeding of the test diet. Comparing fasted plasma samples at each time point, no significant effect (adjusted P < 0·05) of diet on metabolites was observed. In the postprandial state, only phosphate was consistently different between diets and was explained by additional dietary P to maintain Ca:P. Metabolic profiling analysis supports the view that the dietary Ca upper limit is safe. Additionally, the canine plasma metabolome was characterised, providing insights into the stability of individual profiles across 40 weeks, the response to consumption of a nutritionally complete meal over a 4 h postprandial time course and different kinetic categories of postprandial absorption.

Contribution of Palmar Radiocarpal and Ulnocarpal Ligaments to the Stability of the Canine Antebrachiocarpal Joint.

OBJECTIVE: The aim of this study was to evaluate the contribution of the palmar radiocarpal ligament and the palmar ulnocarpal ligament to canine antebrachiocarpal joint stability. MATERIALS AND METHODS: The right carpus of four dog cadavers, free of musculoskeletal pathology, was stripped of muscle. Each specimen was placed into a custom-made joint testing machine and tested at 15° extension, and 0° and 15° flexion. A single motion tracking sensor was fixed to the metacarpal bones. All specimens were tested with all ligaments intact and after transection of the palmar radiocarpal and ulnocarpal ligaments. A range of weights between 0.2 and 2.0 kg was used to test the carpi in three directions (axial, medial/lateral and cranial/caudal) and two moments (pronation/supination and valgus/varus). RESULTS: No differences were found between the translations and rotations of the manus relative to the radius and ulna with the ligaments intact and the ligaments transected at any of the carpal angles tested, except at 15° of flexion. Increasing the angle of flexion resulted in a significant increase in cranial and caudal translation of the manus relative to the radius and ulna both in the intact and transected specimens. CLINICAL RELEVANCE: Antebrachiocarpal joint position plays a more important role in craniocaudal antebrachiocarpal joint stability than the palmar radiocarpal and ulnocarpal ligaments.

Promoting Outdoor Physical Activity for People and Pets: Opportunities for Veterinarians to Engage in Public Health.

Regular physical activity (PA) is a health promoting behavior that transcends species. The collective evidence of a positive relationship between PA and health in both people and animals suggests that implementation of outdoor, dog-associated activities to increase PA may synergistically enhance both human and dog health. A systematic literature review was performed to identify research investigating objective, quantitative health outcomes in both dogs and people exercising together. Within the confines of the search, only 2 studies fulfilled the criteria for complete review. One study was administered through a veterinary clinic and another through a human health care provider. Both studies focused on obesity treatment, either for the dog or for both the dog and the owner. Collectively this work demonstrates the feasibility of simultaneously promoting health in both groups through PA; however there are limitations to the generalizability of the findings. Additional research is needed to further investigate the feasibility and effectiveness of PA promotion in primary care veterinary clinics as well as the use of animal-assisted PA promotion as a preventative, not just therapeutic, tool. As diseases that can be prevented, at least in part, by regular PA are now the leading causes of morbidity and mortality in developed countries, veterinarians have the potential to significantly impact not only the health of their patients, but also that of the public.

Effects of the long-term feeding of diets enriched with inorganic phosphorus on the adult feline kidney and phosphorus metabolism.

Renal disease has a high incidence in cats, and some evidence implicates dietary P as well. To investigate this further, two studies in healthy adult cats were conducted. Study 1 (36 weeks) included forty-eight cats, stratified to control or test diets providing 1·2 or 4·8 g/1000 kcal (4184 kJ) P (0 or approximately 3·6 g/1000 kcal (4184 kJ) inorganic P, Ca:P 1·2, 0·6). Study 2 (29 weeks) included fifty cats, stratified to control or test diets, providing 1·3 or 3·6 g/1000 kcal (4184 kJ) P (0 or approximately 1·5 g/1000 kcal (4184 kJ) inorganic P, Ca:P 1·2, 0·9). Health markers, glomerular filtration rate (GFR) and mineral balance were measured regularly, with abdominal ultrasound. Study 1 was halted after 4 weeks as the test group GFR reduced by 0·4 (95 % CI 0·3, 0·5) ml/min per kg, and ultrasound revealed changes in renal echogenicity. In study 2, at week 28, no change in mean GFR was observed (P >0·05); however, altered renal echogenicity was detected in 36 % of test cats. In agreement with previous studies, feeding a diet with Ca:P <1·0, a high total and inorganic P inclusion resulted in loss of renal function and changes in echogenicity suggestive of renal pathology. Feeding a diet containing lower total and inorganic P with Ca:P close to 1·0 led to more subtle structural changes in a third of test cats; however, nephrolithiasis occurred in both diet groups, complicating data interpretation. We conclude that the no observed adverse effects level for total dietary P in adult cats is lower than 3·6 g/1000 kcal (4184 kJ), however the effect of inorganic P sources and Ca:P require further investigation.

A Comparative Study of Serum Biochemistry, Metabolome and Microbiome Parameters of Clinically Healthy, Normal Weight, Overweight, and Obese Companion Dogs.

The aim of this study was to compare fecal microbiome, plasma, fecal and urine metabolomes, and serum biochemistry of adult companion dogs according to body condition scores. Blood, serum/plasma, urine, and fecal samples were collected from 66 clinically healthy, adult companion dogs of either normal weight (NW), overweight (OW), or obese dogs (OB). analyses included fecal microbiome analyses via 16S ribosomal RNA gene amplicon; sequencing, nontargeted plasma, fecal, and urine metabolomics using liquid chromatography/gas chromatography-mass; spectrometry, and serum biochemistry for each dog. Few significant differences in serum biochemistry and fecal microbiome Operational Taxonomic Unit (OTU) were found between weight groups and there was high OTU variation between individual dogs. NW dogs had higher relative abundance of the genus Eubacterium (log-fold change 4.3, adjusted P value = .003) and lower relative abundance of the family Bifidobacteriaceae (log-fold change -3.6, adjusted P value = .02) compared to OB dogs. The microbiome of NW dogs had higher OTU richness compared with OB dogs. Metabolome analysis showed 185 plasma, 37 fecal, and 45 urine metabolites that significantly differed between NW and OW or OB dogs. There were notable significant differences in relative abundance of several plasma phospholipid moieties and fecal volatile fatty acids between weight phenotypes. The combinations of host and gut microbiota and metabolic shifts suggest a pattern that could help detection of early metabolic changes in overweight dogs before the development of obesity related disease. The results of this study support the need for continued investigation into sensitive measures of metabolic aberrancies in overweight dogs.

Adult dogs are capable of regulating calcium balance, with no adverse effects on health, when fed a high-calcium diet.

Although the implications of long-term high Ca intakes have been well documented in growing dogs, the health consequences of Ca excess in adult dogs remain to be established. To evaluate the impact of feeding a diet containing 7·1 g/4184 kJ (1000 kcal) Ca for 40 weeks on Ca balance and health parameters in adult dogs, eighteen neutered adult Labrador Retrievers, (nine males and nine females) aged 2·5-7·4 years were randomised to one of two customised diets for 40 weeks. The diets were manufactured according to similar nutritional specifications, with the exception of Ca and P levels. The diets provided 1·7 and 7·1 g/4184 kJ (1000 kcal) (200(SD26) and 881(SD145) mg/kg body weight0·75 per d, respectively) Ca, respectively, with a Ca:P ratio of 1·6. Clinical examinations, ultrasound scans, radiographs, health parameters, metabolic effects and mineral balance were recorded at baseline and at 8-week intervals throughout the study. Dogs in both groups were healthy throughout the trial without evidence of urinary, renal or orthopaedic disease. In addition, there were no clinically relevant changes in any of the measures made in either group (all P>0·05). The high-Ca diet resulted in a 3·3-fold increase in faecal Ca excretion (P0·05). Ca intakes of up to 7·1 g/4184 kJ (1000 kcal) are well tolerated over a period of 40 weeks, with no adverse effects that could be attributed to the diet or to a high mineral intake.

Prevalence, distribution, and progression of radiographic abnormalities in the lungs of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii): 89 cases (2002-2005).

OBJECTIVE: To evaluate the prevalence, distribution, and progression of radiographic abnormalities in the lungs of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) and associations between these abnormalities and body weight, carapace length, and hematologic and plasma biochemical variables. DESIGN: Retrospective case series. ANIMALS: 89 cold-stunned juvenile Kemp's ridley sea turtles. PROCEDURES: Medical records were reviewed. Dorsoventral and horizontal beam craniocaudal radiographs were evaluated for the presence, distribution, and progression of lung abnormalities. Turtles were categorized as having radiographically normal or abnormal lungs; those with abnormalities detected were further categorized according to the distribution of abnormalities (left lung, right lung, or both affected). Body weight, carapace length, and hematologic and plasma biochemical data were compared among categories. RESULTS: 48 of 89 (54%) turtles had radiographic abnormalities of the lungs. Unilateral abnormalities of the right or left lung were detected in 14 (16%) and 2 (2%), respectively; both lungs were affected in 32 (36%). Prevalence of unilateral abnormalities was significantly greater for the right lung than for the left lung. Evaluation of follow-up radiographs indicated clinical improvement over time for most (18/31 [58%]) turtles. Prevalence of bilateral radiographic abnormalities was positively correlated with body weight and carapace length. There was no significant association between radiographic category and hematologic or plasma biochemical variables. CONCLUSIONS AND CLINICAL RELEVANCE: Radiographic abnormalities of the lungs were commonly detected in cold-stunned Kemp's ridley turtles. Results of this study may aid clinicians in developing effective diagnostic and treatment plans for these patients.

Physiologic and biochemical measurements and response to noxious stimulation at various concentrations of MS-222 in koi (Cyprinus carpio).

OBJECTIVE: To evaluate the physiological effect and response to noxious stimulation at five concentrations of MS-222 in koi (Cyprinus carpio). STUDY DESIGN: Prospective experimental study. ANIMALS: Twenty-one healthy adult unknown sex koi fish weighing mean 450±SD 120 g. METHODS: Each fish was exposed to five different concentrations of MS-222 (50, 70, 110, 150 and 190 mg L(-1) ) in a random sequence during the same anaesthetic event. For each concentration of MS-222, vital functions such as heart rate (HR) (via Doppler) and opercular rate (OpR) were recorded after a standardized induction period. Response to two noxious stimuli in the form of haemostat clamp pressure applied on the tail and the lip was evaluated, and blood was drawn to measure biochemical and blood gas values. RESULTS: Decrease in response to noxious stimulation with an increase of MS-222 concentration both for the lip (p=0.0027) and the tail (p<0.0001) stimulus was observed. Biochemical values were unaffected by the concentration of MS-222 with the exception of lactate concentration which was weakly correlated with the duration of anaesthesia (r=0.31, p<0.001) and the number of times the fish was clamped or bled prior to sampling (r=0.23, p<0.001). Opercular rate decreased with the increase in anaesthetic concentration, and HR was not affected. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicated a decrease in response to stimulus and a decrease in OpR that were associated with increased concentrations of MS-222. This may assist in establishing anaesthetic protocols using MS-222 in fish and supports the use of supramaximal pressure stimuli to teleost fish under variable MS-222 concentrations as a model for future studies.

West Nile virus infection in a green-winged macaw (Ara chloropterus).

A 29-year-old female green-winged macaw (Ara chloropterus) was presented for acute pelvic limb lameness. On physical examination the bird was found to be mildly dehydrated with paraparesis and proprioceptive deficits of the pelvic limbs. Antemortem diagnostics included a complete blood count and plasma biochemistry panel, fecal Gram and Ziehl-Neelsen acid fast stains, plasma heavy metal concentrations, reverse transcriptase (RT)-PCR testing for West Nile virus (WNV) RNA and PCR testing for Chlamydophila psittaci DNA from choanal/cloacal swabs, and survey radiography. Abnormal findings included a heterophilic leukocytosis, elevated kidney and muscle enzyme values, and a positive RT-PCR result for West Nile viral RNA. Although the bird showed some improvement with supportive care, on the fourth day it began having seizures and was euthanatized. There were no abnormal findings detected on gross necropsy; however, histopathology revealed mononuclear inflammatory cell infiltration in multiple organs including brain, heart, and pancreas. WNV antigen and RNA were detected using immunohistochemistry and RT-PCR in various tissues including brain, pancreas, and spleen. WNV was successfully isolated from brain, pancreas, spleen, and liver. To our knowledge, this is the first report characterizing WNV disease in a green-winged macaw and one of few reports of this disease in a psittacine bird.