Grain-free Diets Research Articles

Postprandial Plasma and Whole Blood Amino Acids Are Largely Indicative of Dietary Amino Acids in Adult Dogs Consuming Diets with Increasing Whole Pulse Ingredient Inclusion

BackgroundPulse ingredients often replace grains in grain-free dog diets owing to their high-protein content. However, research to ascertain the benefit of this modification is limited. ObjectivesThis study aimed to correlate food compounds in 1 corn-inclusive control diet and 3 grain-free diets with increasing inclusions of whole pulses (≤45%; Pulse15, Pulse30, and Pulse45), formulated to meet similar macronutrient and micronutrient targets with postprandial amino acids (AAs) in healthy dogs >20 wk. MethodsDiets were analyzed for biochemical compounds using tandem mass spectrometry. Twenty-eight outdoor-housed, healthy, adult Siberian Huskies were allocated to diet, and meal responses were analyzed at baseline and weeks 2, 4, 8, 16, and 20 with samples collected at fasted and 15, 30, 60, 90, 120, and 180 min after meal presentation. Blood AAs were analyzed by ultra performance liquid chromatography and differences across week, treatment, and time postmeal were analyzed in SAS Studio. Partial least squares regression was performed in SAS Studio using biochemical compounds in the diet as predictor variables and blood AAs as response variables. ResultsIn plasma, Pulse45 had ∼32% greater postprandial Asn than Pulse15, and the control diet had ∼34% greater postprandial Leu and ∼35% greater Pro than Pulse15 (P < 0.05). In whole blood, Pulse30 had ∼23% greater postprandial Lys than the control diet, and the control diet had ∼21% greater postprandial Met and ∼18% greater Pro than Pulse45 and Pulse30, respectively (P < 0.05). Several phospholipids were correlated with postprandial AAs. Compounds in the urea cycle and glycine and serine metabolism were more enriched (P < 0.05) in plasma and whole blood, respectively. ConclusionsIn macronutrient-balanced and micronutrient-balanced canine diets that differ in their inclusion of corn-derived compared with pulse-derived ingredients, postprandial changes in circulating AAs are largely indicative of the dietary AAs. This helps further our understanding of AA metabolism in healthy dogs fed grain-free diets.

Effects of single and twin thermal screw extrusion on protein quality of grain-free pet foods formulated with predominantly animal- or plant-based protein ingredients

With the diversification of the pet food industry and increasing market demand, the inclusion of plant protein in companion animal diets has become of interest. Pulses, commonly seen in grain-free diets, are high in protein and could serve as an alternative source of animal-based protein. There has been research on the ingredient about nutrient profiles and effects on canine health. However, little is known about the amino acid availability when pulses are incorporated into diets. In addition, there is lacking in knowledge about the effect of extrusion processing on protein quality and the possible interaction between processing and ingredients. Therefore, the study was conducted to determine the effect of extrusion and pulses on amino acid digestibility and protein quality. Eight grain-free diet formulations were designed: chicken byproduct meal diet (CON), chicken slurry diet (SLR), chicken slurry + yellow pea diet (SLR+YP), yellow pea diet (YP), green lentil diet (GL), garbanzo bean diet (GB), chicken slurry + taurine diet (SLR+TAU), and chicken slurry + yellow pea + taurine diet (SLR+YP+TAU). Two types of extruders were used: single screw and twin screw extruder. Diet samples were taken at 3 processing time points: raw ingredients, at the end of the preconditioner, and at the end of the extruder. The resulting 48 diet samples were analyzed for chemical composition and fed to cecectomized roosters (n=4/treatment) to determine standardized ileal amino acid digestibility and Digestible Indispensable Amino Acid Score (DIAAS)-like values. Even though the diets were mostly similar in chemical composition, methionine content was lower in diets containing yellow pea and green lentil. Extrusion processing did not have negative effect on natural or synthetic taurine in the diets. Preconditioning and extrusion also increased amino acid digestibility and DIAAS-like values in most diets, as processed diets could be considered well-digested and of good protein quality. According to reference protein sources, tryptophan and methionine were the most limiting amino acids in all treatment diet samples. In conclusion, grain-free diet formulation could result in good protein quality in canine diets and extrusion processing increased amino acid digestibility and protein quality.

Diet-Mediated Dilated Cardiomyopathy in the Canine

Dilated cardiomyopathy (DCM) is a disease of the heart muscle resulting in decreased myocardial function and is the second most common myopathy in canine. Previously, canine dilated cardiomyopathy was considered to be an inherited disease among large and giant breeds, however, recent reports suggest a possible link between certain grain-free diets and this condition. Several investigations into the incidence of this condition in relationship to grain-free diet consumption have been conducted in recent years. The most recent research shows a static overall trend in the incidence of DCM despite a five-fold increase in the sales of grain-free pet foods. Inadequate intake of protein, taurine, and specific sulfur-containing amino acids may have a potential role in the development of DCM, as these nutrients are crucial for cardiac muscle development and function. However, significant research remains to be done on the topic to discern any potential definitive causation.

Effects of a 28-day feeding trial of grain-containing versus pulse-based diets on cardiac function, taurine levels and digestibility in domestic dogs.

In 2018, the US Food and Drug Administration reported a link between canine dilated cardiomyopathy (DCM) and grain-free diets. Evidence to support a link has emerged, but the specific ingredients responsible and the role of taurine or other causative factors remain unclear. We hypothesized dogs fed pulse-based, grain-free diets for 28 days will show decreased macronutrient digestibility, increased fecal bile acid excretion, and reduced plasma cystine, cysteine, methionine and taurine, causing sub-clinical cardiac or blood changes indicative of early DCM. Three diets were formulated using white rice flour (grain), whole lentil (grain-free), or wrinkled pea (grain-free) and compared to the pre-trial phase on a commercial grain-based diet. After 28 days of feeding each diet, the wrinkled pea diet impaired stroke volume and cardiac output, increased end-systolic ventricular diameter and increased plasma N-Terminal Pro-B-type Natriuretic Peptide (NT-ProBNP), albeit in a sub-clinical manner. Digestibility of some macronutrients and sulphur-containing amino acids, excluding taurine, also decreased with pulse-based compared to grain-based diets, likely due to higher fiber levels. Plasma taurine levels were unchanged; however, plasma methionine was significantly lower after feeding all test diets compared to the commercial diet. Overall, DCM-like changes observed with the wrinkled pea diet, but not lentil diet, after only 4 weeks in a breed not known to be susceptible support a link between pea-based diets and canine nutritionally-mediated DCM.

117 Assessment of Complete Blood Count and Biochemistry Parameters in Adult Dogs fed a Grain-Free Diet with up to Forty-Five Percent Pulse Inclusion

Abstract With interest in grain-free diets (GFD) and plant-based diets, understanding the use of pulse ingredients is warranted. Recently our laboratory found that high pulse inclusive diets did not cause echocardiographic changes in healthy adult dogs after 20 weeks of feeding. Thus, the objective of this study was to assess the safety of pulse ingredient inclusion up to 45% in canine diets using gross physiological, hematological and biochemical measurements. Twenty-eight healthy adult Siberian huskies were fed one of four experimental diets formulated to achieve the same macronutrient targets and the same micronutrient supplementation for 20 weeks: 1) grain-inclusive diet, with 45% corn, 0% pulses (Control); 2) GFD, 15% pulses (Pulse15); 3) GFD, 30% pulses (Pulse30) 4) GFD, 45% pulses (Pulse45). All diets included chicken meal and the same combination of pulse ingredients; green and yellow peas, pinto beans, chickpeas, and lentils. Dogs were fed once daily. Body weight was measured weekly, feed intake measured daily, and body composition was measured using DEXA at baseline and week 20. Fasted blood samples were collected at weeks -3, 3, 6, 10, 14 and 18. Data were analyzed as repeated measures in SAS using PROC GLIMMIX. Body weight, body composition, and feed intake were similar among treatments and over time (P &amp;gt;0.05). Several blood parameters were different among treatments but remained within defined reference ranges for healthy dogs. Red blood cells, hemoglobin and carbon dioxide were greater, while lymphocytes were reduced in Pulse45 than Pulse15 (P&amp;lt; 0.05), but similar to Control and Pulse30. Mean corpuscular hemoglobin concentration was decreased in Control and Pulse15 compared with Pulse30 and Pulse45 (P&amp;lt; 0.05). Gamma-glutamyl transferase was less in Control and Pulse15 than Pulse45 (P&amp;lt; 0.05), but similar to Pulse30. These data suggest that feeding diets with up to 45% pulse inclusion for 20 weeks does not impact gross health parameters of healthy adult dogs.

Untargeted global metabolomic profiling of healthy dogs grouped on the basis of grain inclusivity of their diet and of dogs with subclinical cardiac abnormalities that underwent a diet change.

To compare metabolomic profiles of dogs eating grain-free (GF) versus grain-inclusive (GI) diets (1) for healthy dogs at baseline and (2) for dogs with subclinical cardiac abnormalities at 12 months after a diet change. Serum samples from 23 dogs eating GF diets and 79 dogs eating GI diets, of which 17 (8 eating a GF diet and 9 eating a GI diet) were reevaluated 12 months after a diet change. Metabolomic profiles were developed by means of ultrahigh-performance liquid chromatography-tandem mass spectroscopy of serum samples. Baseline results for the GF group were compared with those for the GI group. Dogs from both groups with subclinical cardiac abnormalities were transitioned to a GI, pulse-free, intervention diet, and samples collected 12 months later were compared between diet groups. Statistical significance for biochemical group differences was defined as P < .05 with a false discovery rate (q) < .10. Baseline differences in lipid metabolism and amino acid metabolism were found between the GF and GI diet groups. There were 46 metabolites that were higher and 82 metabolites that were lower in the GF group (n = 23), compared with the GI group (79). Comparison of the GF (n = 8) and GI (9) groups 12 months after the diet change showed only 6 metabolites that were higher and 11 metabolites that were lower in the GF group, compared with the GI group. Metabolomic pathway differences between dogs eating GF versus GI diets highlight the important effect of diet in metabolomics analyses. The clinical importance of these differences and how they might relate to cardiac disease in dogs remains undetermined.

Responses in randomised groups of healthy, adult Labrador retrievers fed grain-free diets with high legume inclusion for 30 days display commonalities with dogs with suspected dilated cardiomyopathy

Early responses in healthy adult dogs fed grain-free diets with high inclusion of split peas (20%) and lentils (40%) that may lead to canine diet-induced dilated cardiomyopathy (DCM) were investigated. To help understand the clinical relevance of the findings, a survey of electronic health records (EHR) was conducted of dogs with and without suspected DCM for comparison. Control and Test diets were fed to Labrador retriever dogs for 30 days (n = 5 and 6, respectively). Blood and urine samples collected at baseline and days 3, 14 and 28/30 were analyzed for hematology, clinical biochemistry and taurine concentrations. The EHRs of dogs at Banfield® Pet Hospitals in the 2-year period 2018-2019 were surveyed, revealing 420 dogs diagnosed with DCM, which were compared with 420 breed, gender and age-matched healthy control dogs. Compared to baseline values, feeding the Test diet for 28 days caused progressive, significant (p < 0.001) decreases in red blood cell counts (RBC), hematocrit and total hemoglobin by 7.7, 8.3 and 6.3%, respectively, and a 41.8% increase in plasma inorganic phosphate. Commonalities in these parameters were observed in clinical DCM cases. Regarding taurine status, Test dogs transiently increased whole-blood (23.4%) and plasma (47.7%) concentrations on day 14, while taurine:creatinine ratio in fresh urine and taurine in pooled urine were reduced by 77 and 78%, respectively, on day 28/30. Thus grain-free, legume-rich Test diets caused reduced RBC and hyperphosphatemia, findings also indicated in dogs with suspected DCM. Changes in taurine metabolism were indicated. The data will aid in generating hypotheses for future studies.

Effect of diet change in healthy dogs with subclinical cardiac biomarker or echocardiographic abnormalities.

BackgroundA recent study showed higher high‐sensitivity cardiac troponin I (hs‐cTnI) concentrations in healthy dogs eating grain‐free (GF) compared to those eating grain‐inclusive (GI) diets.Hypothesis/ObjectivesHealthy dogs with subclinical cardiac abnormalities eating GF diets at baseline will show improvements in cardiac biomarkers and echocardiographic variables after diet change, whereas healthy dogs eating GI diets at baseline will not improve.AnimalsTwenty healthy dogs with subclinical cardiac abnormalities (12 Golden Retrievers, 5 Doberman Pinschers, 3 Miniature Schnauzers).MethodsThis prospective study included dogs with increased hs‐cTnI or N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) concentrations, or echocardiographic abnormalities. Mixed modeling was used to evaluate echocardiographic, hs‐cTnI, and NT‐proBNP differences between groups (GF or GI diet at baseline) over time (1 y after diet change).ResultsTen GF and 10 GI dogs were evaluated. There were statistically significant time: group interactions for hs‐cTnI (P = .02) and normalized left ventricular internal systolic diameter (LVIDsN; P = .02), with GF dogs showing larger decreases in these variables than GI dogs. Median (range) hs‐cTnI (ng/mL) for GF dogs was 0.141 (0.012‐0.224) at baseline and 0.092 (0.044‐0.137) at 1 y, and for GI dogs was 0.051 (0.016‐0.195) at baseline and 0.060 (0.022‐0.280) at 1 y. Median LVIDsN for GF dogs was 1.01 (0.70‐1.30) at baseline and 0.87 (0.79‐1.24) at 1 y, and for GI dogs was 1.05 (0.84‐1.21) at baseline and 1.10 (0.85‐1.28) at 1 y.Conclusions and Clinical ImportanceDecreased hs‐cTnI and LVIDsN in GF dogs after diet change supports reversibility of these subclinical myocardial abnormalities.

119 Awardee Talk: A Matter of the Heart: The Use of Pulses in Canine and Feline Nutrition

Abstract In the pet food industry, the popularity of plant-based protein sources has risen as consumer demand for grain-free and novel protein sources increase. However, minimal research has been conducted as regards use of pulses and their effects on acceptability and digestibility in canine and feline nutrition. In addition, market shift towards grain-free and pulse-rich diets has presented concerns about the suitability of pulses as viable protein sources. In July 2018, the FDA published a press release discussing a potential link between diets containing legumes and the development of dilated cardiomyopathy (DCM) in dogs. As such, part of our research program has focused on the 1) characterization of the macronutrient composition and protein quality of plant-based protein sources, 2) evaluation of the effects of plant-based protein sources in extruded canine and feline diets on macronutrient digestibility, and modulation of fecal microbiota and metabolites, and 3) determination of the longitudinal effects of high pulse inclusion in diets on taurine status in dogs. Pulse ingredients contained approximately 20% crude protein, and had methionine or tryptophan as the first-limiting amino acids using the precision-fed cecectomized rooster assay. When incorporated in canine and feline diets, pulses did not result in negative effects on macronutrient digestibility or fecal scores. However, shifts in fecal microbial and metabolites were observed in animals fed pulse-based in contrast with animal-based protein diets. The inclusion of 45% green lentils in extruded diets did not cause decreased plasma or whole blood taurine or methionine levels. Additionally, excess taurine was not depleted from these animals in the urine or feces. Taurine status was considered normal in these dogs, despite changes in fecal bile acid concentrations and microbiota. Although we are currently carrying out further research projects investigating potential association of pulse rich diets and canine DCM. Current research findings from our laboratory suggest the inclusion of pulses may not be the causative factor. The use of plant-based proteins as ingredients in canine and feline diets not only meet consumer demand but also provide a valuable, safe, and nutritionally adequate alternative to traditional protein sources.

Roles of plant-based ingredients and phytonutrients in canine nutrition and health.

Dogs possess the ability to obtain essential nutrients, established by the Association of American Feed Control Officials (AAFCO), from both animal‐ and plant‐based ingredients. There has been a recent increase in the popularity of diets that limit or completely exclude certain plant‐based ingredients. Examples of these diets include ‘ancestral’ or ‘evolutionary’ diets, raw meat‐based diets and grain‐free diets. As compared to animal sources, plant‐derived ingredients (including vegetables, fruits, grains, legumes, nuts and seeds) provide many non‐essential phytonutrients with some data suggesting they confer health benefits. This review aims to assess the strength of current evidence on the relationship between the consumption of plant‐based foods and phytonutrients (such as plant‐derived carotenoids, polyphenols and phytosterols) and biomarkers of health and diseases (such as body weight/condition, gastrointestinal health, immune health, cardiovascular health, visual function and cognitive function) from clinical trials and epidemiological studies. This review highlights the potential nutritional and health benefits of including plant‐based ingredients as a part of balanced canine diets. We also highlight current research gaps in existing studies and provide future research directions to inform the impact of incorporating plant‐based ingredients in commercial or home‐prepared diets.

Addition of dietary methionine but not dietary taurine or methyl donors/receivers to a grain-free diet increases postprandial homocysteine concentrations in adult dogs.

Grain-based ingredients are replaced in part by pulse ingredients in grain-free pet foods. Pulse ingredients are lower in methionine and cysteine, amino acid (AA) precursors to taurine synthesis in dogs. Although recent work has investigated plasma and whole blood taurine concentrations when feeding grain-free diets, supplementation of a grain-free diet with various nutrients involved in the biosynthesis of taurine has not been evaluated. This study aimed to investigate the effects of supplementing a complete grain-free dry dog food with either methionine (MET), taurine (TAU), or methyl donors (choline) and methyl receivers (creatine and carnitine; CCC) on postprandial AA concentrations. Eight healthy Beagle dogs were fed one of the three treatments or the control grain-free diet (CON) for 7 d in a 4 × 4 Latin square design. On day 7, cephalic catheters were placed and one fasted sample (0 min) and a series of nine post-meal blood samples were collected at 15, 30, 60, 90, 120, 180, 240, 300, and 360 min. Data were analyzed as repeated measures using the PROC GLIMMIX function in SAS (Version 9.4). Dogs fed MET had greater plasma and whole blood methionine concentrations from 30 to 360 min after a meal (P < 0.0001) and greater plasma homocysteine concentrations from 60 to 360 min after a meal (P < 0.0001) compared with dogs fed CON, TAU, and CCC. Dogs fed TAU had greater plasma taurine concentrations over time compared with dogs fed CON (P = 0.02) but were not different than dogs fed MET and CCC (P > 0.05). In addition, most AAs remained significantly elevated at 6 h post-meal compared with fasted samples across all treatments. Supplementation of creatine, carnitine, and choline in grain-free diets may play a role in sparing the methionine requirement without increasing homocysteine concentrations. Supplementing these nutrients could also aid in the treatment of disease that causes metabolic or oxidative stress, including cardiac disease in dogs, but future research is required.

The Effects of 7 Days of Feeding Pulse-Based Diets on Digestibility, Glycemic Response and Taurine Levels in Domestic Dogs.

Grain-based carbohydrate sources such as rice comprise 30–50% of commercial pet foods. Some pet foods however have removed the use of grains and have instead incorporated pulses, such as peas and lentils, resulting in grain-free diets. The hypothesis was dog diets with higher levels of dietary fiber will produce a low glycemic response due to decreased rates of digestion and lowered bioavailability of all macronutrients and increased fecal bile salt excretion. This in turn was hypothesized to produce lower plasma concentrations of cysteine, methionine and taurine after 7 days of feeding each test diet in dogs. Six diets were formulated at an inclusion level of 20% available carbohydrate, using white rice flour (grain) or whole pulse flours from smooth pea, fava bean, red lentil or 2 different wrinkled pea varieties (CDC 4,140–4 or Amigold) and fed to beagles in a randomized, cross-over, blinded design. After 7 days feeding each diet, fasting blood glucose was the lowest in the lentil (3.5 ± 0.1 mmol/L) and wrinkled pea (4,140–4; 3.6 ± 0.1 mmol/L) diet periods, while peak glucose levels was lowest after feeding the lentil diet (4.4 ± 0.1 mmol/L) compared to the rice diet. Total tract apparent digestibility of all macronutrients as well as taurine differed among diets yet plasma taurine was not outside normal range. Decreased macronutrient and amino acid digestibility was associated with increasing amylose and dietary fiber content but the specific causative agent could not be determined from this study. Surprisingly, digestibility decreases were not due to increased bile salt loss in the feces since increasing dietary fiber content led to decreased fecal bile salt levels. In conclusion, although pulse-based canine diets have beneficial low glycemic properties, after only 7 days, these pulse-based diets decrease macronutrient and amino acid digestibility. This is likely related at least in part to the lower animal protein content, but on a long-term basis could put domestic dogs at risk for low taurine and dilated cardiomyopathy.

Diet associated canine dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a common cause of heart failure in the dog. Primary DCM is often a disease of exclusion, but inherited genetic breed dispositions have been reported. Secondary causes of DCM include toxins, nutritional deficiency, systemic and infectious disease. The number of dogs diagnosed with DCM has increased significantly in the last 20 years, and has been linked to the rise in popularity of boutique, exotic and grain-free, legume-rich diets. Veterinary cardiologists raised concerns as DCM was being reported in atypical breeds. Subsequently, the United States Food and Drug Agency released a statement in 2018 warning pet owners of the risks of grain-free and novel protein diets. It is assumed that the problem also occurs in the UK because these diets are popular here also. Contrary to primary causes of DCM, dogs have improved clinically and on echocardiograph when their diet has been changed and/or supplemented. No clear cause has yet been identified between these diets and DCM, but the potential reasons seem to be multifactorial and limited by a lack of understanding of the bioavailability, digestibility and metabolism of the novel proteins and legume-rich diets.

Effect of type of diet on blood and plasma taurine concentrations, cardiac biomarkers, and echocardiograms in 4 dog breeds.

BackgroundAssociations of diet with dilated cardiomyopathy are under investigation.ObjectivesThat cardiac assessment would show abnormalities in healthy dogs eating grain‐free (GF) diets or diets with Food and Drug Administration (FDA)‐listed ingredients of concern (peas, lentils, or potatoes) as top 10 ingredients (FDA‐PLP), but not in dogs eating grain‐inclusive (GI) diets or diets without FDA‐listed ingredients of concern (PLP) in the top 10 ingredients (NoFDA‐PLP).AnimalsOne hundred eighty‐eight healthy Doberman Pinschers, Golden Retrievers, Miniature Schnauzers, and Whippets.MethodsThis study was an observational cross‐sectional study. Echocardiograms, cardiac biomarkers, and blood and plasma taurine concentrations were compared between dogs eating GF (n = 26) and GI (n = 162) diets, and between FDA‐PLP (n = 39) and NoFDA‐PLP (n = 149) diets, controlling for age and breed. Demographic characteristics, murmurs, genetic status, and ventricular premature complexes (VPCs) during examination were compared between dogs eating different diet types.ResultsNo differences in echocardiographic variables, N‐terminal pro‐B‐type natriuretic peptide or whole blood taurine were noted between dogs eating different diet types. Dogs eating GF diets had higher median high‐sensitivity cardiac troponin I (hs‐cTnI) (GF 0.076 ng/mL [Interquartile range (IQR), 0.028‐0.156] vs. GI 0.048 [IQR, 0.0026‐0.080]; P < .001) and higher median plasma taurine (GF 125 nmol/mL [IQR, 101‐148] vs GI 104 [IQR, 86‐123]; P = .02) than dogs eating GI diets. Dogs eating FDA‐PLP diets had higher median hs‐cTnI (0.059 ng/mL [IQR, 0.028‐0.122]) than dogs eating NoFDA‐PLP diets (0.048 [IQR, 0.025‐0.085]; P = .006). A greater proportion of dogs eating FDA‐PLP diets (10%) had VPCs than dogs eating NoFDA‐PLP diets (2%; P = .04).Conclusions and Clinical ImportanceHigher hs‐cTnI in healthy dogs eating GF and FDA‐PLP diets might indicate low‐level cardiomyocyte injury.

PSXI-28 Commercial grain-free diet improved taurine status, but increased bile acid excretion when fed to Labrador Retrievers

Abstract In 2018 the Food and Drug Administration (FDA) released a statement that grain-free diets may be related to the increased incidence of dilated cardiomyopathy (DCM) in dogs. This statement was made despite all implicated diets meeting nutrient requirements published by the Association of American Feed Controls Official (AAFCO) and enforced by State Officials. Many of these dogs presented with low plasma or whole blood taurine concentrations, and as such, we hypothesized that feeding these diets would result in reduced taurine status over a 26 wk feeding period. The objective of this study was to determine the effects of feeding a grain-free diet to large breed dogs on taurine status and overall health. Eight Labrador Retrievers (4 males, 4 females; Four Rivers Kennel, MO) were individually housed and fed a commercial complete and balanced grain-free diet (Acana Pork and Squash formula; APS; moisture 8.40%, crude protein 37.81%, crude fat 18.78%, ash 8.06%, and total dietary fiber 11.40%) for 26 weeks. Fasted blood samples were collected at week 0 and 26 for analyses of plasma and whole blood taurine. Urine was collected by free catch and analyzed for taurine and creatinine. Fresh fecal samples were collected and analyzed for bile acids. Data were analyzed using the GLIMMIX procedure with repeated measures in SAS (v. 9.4). Dogs were healthy throughout the duration of the trial. Urinary taurine to creatinine ratio did not change throughout the feeding period (wk 0 = 0.25 vs. wk 26 = 0.28). Fecal bile acid excretion increased after 26 weeks of feeding APS to dogs. Despite the higher fecal excretion of bile acids, plasma and whole blood taurine increased over the 26 wk feeding period. In conclusion, feeding APS for 26 wk results in increased taurine status in large breed dogs, despite higher excretion of fecal bile acids.

83 The acute effects of feeding a grain-free diet with or without methionine, taurine or methyl donor/acceptor supplementation on plasma and whole blood amino acid concentrations in dogs

Abstract Grain-free pet foods have been sold for over a decade and comprise more than 40% of dog and cat diets sold today. Grain-free diets replace grain ingredients with pulse ingredients, which are high in lysine but low in methionine and cysteine, the precursor amino acids to taurine synthesis in the dog. The objective of this study was to evaluate the postprandial response of plasma methionine and taurine and whole blood taurine concentrations of dogs fed a grain-free diet without supplementation (CON) or with methionine (MET), taurine (TAU) or creatine, carnitine and choline (CCC) supplementation. Eight Beagles were pair housed and fed one of the four experimental diets for seven days in a 4x4 Latin Square Design. On the morning of d 7, cephalic catheters were placed and one fasted sample (0 min) and nine post-meal blood samples (15, 30, 60, 90, 120, 180, 240, 300 and 360 min) were collected. Data were analyzed as repeated measures using the PROC GLIMMIX function in SAS (Version 9.4). Dogs supplemented with MET had significantly higher plasma methionine concentrations from 30 to 360 minutes post-meal compared to dogs on CON, TAU and CCC treatments (P &amp;lt; 0.05). However, no differences were observed in plasma methionine concentrations between CON, TAU and CCC treatments at any time point (P &amp;gt; 0.05). Plasma taurine concentrations were significantly higher across time points in all treatment groups compared to CON (P &amp;lt; 0.05). Whole blood taurine concentrations tended to be higher across time points in MET and TAU treatment groups compared to CCC (P = 0.0513). Overall, MET, TAU and CCC supplementation increased plasma taurine concentrations compared to CON, but only MET supplementation increased plasma methionine concentrations from 30 to 360 minutes post-meal.

A commercial grain-free diet does not decrease plasma amino acids and taurine status but increases bile acid excretion when fed to Labrador Retrievers.

Grain-free diets tend to have greater inclusions of pulses in contrast to grain-based diets. In 2018, the Food and Drug Administration (FDA) released a statement that grain-free diets may be related to the development of canine dilated cardiomyopathy (DCM). However, all dog foods met regulatory minimums for nutrient inclusion recommended by the Association of American Feed Controls Official. In some FDA case reports, but not all, dogs diagnosed with DCM also had low concentrations of plasma or whole blood taurine; thus, we hypothesized that feeding these diets will result in reduced taurine status from baseline measures. The objective of this study was to determine the effects of feeding a grain-free diet to large-breed dogs on taurine status and overall health. Eight Labrador Retrievers (four males and four females; Four Rivers Kennel, MO) were individually housed and fed a commercial complete and balanced grain-free diet (Acana Pork and Squash formula; APS) for 26 wk. Fasted blood samples were collected prior to the start of the trial (baseline; week 0) and at weeks 13 and 26 for analyses of blood chemistry, hematology, plasma amino acids, and whole blood taurine. Urine was collected by free catch at weeks 0 and 26 for taurine and creatinine analyses. Fresh fecal samples were collected at weeks 0 and 26 for bile acid analyses. Data were analyzed using the GLIMMIX procedure with repeated measures in SAS (v. 9.4). Plasma His, Met, Trp, and taurine and whole blood taurine concentrations increased over the course of the study (P < 0.05). Urinary taurine to creatinine ratio was not affected by diet (P > 0.05). Fecal bile acid excretion increased after 26 wk of feeding APS to dogs. Despite the higher fecal excretion of bile acids, plasma and whole blood taurine increased over the 26-wk feeding study. These data suggest that feeding APS, a grain-free diet, over a 26-wk period improved taurine status in Labrador Retrievers and is not the basis for the incidence of DCM for dogs fed APS. Other factors that may contribute to the etiology of DCM should be explored.

Review of canine dilated cardiomyopathy in the wake of diet-associated concerns.

Dilated cardiomyopathy (DCM) has been in the literature and news because of the recent opinion-based journal articles and public releases by regulatory agencies. DCM is commonly associated with a genetic predisposition in certain dog breeds and can also occur secondary to other diseases and nutritional deficiencies. Recent communications in veterinary journals have discussed a potential relationship between grain-free and/or novel protein diets to DCM, citing a subjective increase in DCM in dog breeds that are not known to have a genetic predisposition for the disease. This literature review describes clinical presentations of DCM, common sequelae, treatment and preventative measures, histopathologic features, and a discussion of the varied etiological origins of the disease. In addition, current literature limitations are addressed, in order to ascertain multiple variables leading to the development of DCM. Future studies are needed to evaluate one variable at a time and to minimize confounding variables and speculation. Furthermore, to prevent sampling bias with the current FDA reports, the veterinary community should be asked to provide information for all cases of DCM in dogs. This should include cases during the same time period, regardless of the practitioner’s proposed etiology, due to no definitive association between diets with specific characteristics, such as, but not limited to, grain-free diets and those containing legumes, novel protein diets, and those produced by small manufacturers to DCM in dogs. In summary, in order to determine if certain ingredients, categories of diets, or manufacturing processes are related to an increased risk of DCM, further studies investigating these variables are necessary.

Development of plasma and whole blood taurine reference ranges and identification of dietary features associated with taurine deficiency and dilated cardiomyopathy in golden retrievers: A prospective, observational study.

IntroductionA surge in Food and Drug Administration (FDA) consumer complaints identified concerns that legume-rich, grain-free diets were associated with nutritionally-mediated dilated cardiomyopathy (DCM). Golden retrievers represent the most reported breed affected by this condition and previous studies documented the disease is responsive to dietary change and taurine supplementation. Although dietary findings across cases are compelling, prospective studies with control groups are lacking. The role of diet in developing taurine deficiency and echocardiographic changes consistent with DCM in healthy dogs is unknown.ObjectivesWe hypothesized that golden retrievers eating non-traditional diets are at a higher risk of having taurine deficiency and nutritionally-mediated DCM compared with those eating traditional commercial diets. We aimed to compare taurine concentrations and echocardiographic indices of systolic function between golden retrievers in each diet group and elucidate associations between diet and these variables. Additionally, we aimed to generate breed-specific reference intervals for whole blood and plasma taurine concentrations.Animals86 golden retrievers.MethodsGolden retrievers eating traditional or non-traditional diets were evaluated and diet history, taurine concentrations and echocardiographic data were collected. Dietary features, taurine concentrations and echocardiographic findings were compared between diet groups. Relative risks were calculated for the likelihood of echocardiographic abnormalities and taurine deficiency in each diet group. Breed-specific reference intervals were constructed for taurine concentrations in dogs from the traditional diet group.ResultsGolden retrievers eating non-traditional diets had significantly lower taurine concentrations and more frequent systolic dysfunction. Breed specific reference intervals are higher than previously reported across breeds.ConclusionsNon-traditional diets, which were typically grain-free and contained legumes in this study, were significantly associated with and have increased relative risk for the identification of taurine deficiency and echocardiographic abnormalities consistent with nutritionally-mediated DCM. These findings were identifiable in the absence of clinical signs and support the findings of multiple previous studies and the ongoing FDA investigation.

Starch characterization of commercial extruded dry pet foods.

Starches provide an effective energy source for dogs and cats and can affect health according to its inclusion and extent of digestion. The starch fraction that escapes small intestine (SI) digestion is called resistant starch (RS) and is desirable due to its prebiotic function. Starch is not an essential nutrient for dogs and cats and thus is not reported on commercial pet food labels. Hence, the objective of this work was to characterize starches in commercial pet foods. The top five pet food companies by sales were selected to represent U.S. pet foods, which were divided into four strata with a sampling frame of 654 foods: dog grain based (372 foods), dog grain free (71 foods), cat grain based (175 foods), and cat grain free (38 foods). Five random foods within each stratum were purchased (20 total). Starch analyses (total starch, resistant starch, and starch cook), as well as nutrient analyses were conducted on all foods. Total starch, RS, and starch cook means were compared using a two-group Z-test on dog vs. cat and grain-based (GB) vs. grain-free (GF) diets, and differences were considered significant at a P < 0.05. Total starch was higher (P < 0.05) in dog than cat food, and starch cook was greater (P < 0.05) in GF diets. A regression analysis showed that nitrogen-free extract was a good predictor of total starch. Resistant starch was low and not different among groups. A post hoc test showed that a total sample size of at least 28 diets per group would be required to detect differences in RS between GF and GB diets, if one exists.