Taurine deficiency in Newfoundlands fed commercially available complete and balanced diets

OBJECTIVE: To determine taurine status in a large group of Newfoundlands related by environment, diet, or breeding to a dog with dilated cardiomyopathy and taurine deficiency. DESIGN: Prospective study. ANIMALS: 19 privately owned Newfoundlands between 5 months and 11.5 years old that had been fed commercial dry diets meeting established nutrient recommendations. PROCEDURE: Diet histories were obtained, and blood, plasma, and urine taurine concentrations and plasma methionine and cysteine concentrations were measured. In 8 dogs, taurine concentrations were measured before and after supplementation with methionine for 30 days. Ophthalmic examinations were performed in 16 dogs; echocardiography was performed in 6 dogs that were taurine deficient. RESULTS: Plasma taurine concentrations ranged from 3 to 228 nmol/mL. Twelve dogs had concentrations < 40 nmol/mL and were considered taurine deficient. For dogs with plasma concentrations < 40 nmol/mL, there was a significant linear correlation between plasma and blood taurine concentrations. For dogs with plasma concentrations > 40 nmol/mL, blood taurine concentrations did not vary substantially. Taurine-deficient dogs had been fed lamb meal and rice diets. Retinal degeneration, dilated cardiomyopathy, and cystinuria were not found in any dog examined for these conditions. The taurine deficiency was reversed by a change in diet or methionine supplementation. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate a high prevalence of taurine deficiency among an environmentally and genetically related cohort of Newfoundlands fed apparently complete and balanced diets. Blood taurine concentrations indicative of taurine deficiency in Newfoundlands may be substantially less than concentrations indicative of a deficiency in cats.     

Taurine deficiency in dogs with dilated cardiomyopathy: 12 cases (1997-2001)

OBJECTIVE: To determine signalment, history, clinical signs, blood and plasma taurine concentrations, electrocardiographic and echocardiographic findings, treatment, and outcome of dogs with low blood or plasma taurine concentrations and dilated cardiomyopathy (DCM). DESIGN: Retrospective study. ANIMALS: 12 client-owned dogs with low blood or plasma taurine concentrations and DCM. PROCEDURE: Medical records were reviewed, and clinical data were obtained. RESULTS: All 12 dogs were being fed a commercial dry diet containing lamb meal, rice, or both as primary ingredients. Cardiac function and plasma taurine concentration improved with treatment and taurine supplementation. Seven of the 12 dogs that were still alive at the time of the study were receiving no cardiac medications except taurine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that consumption of certain commercial diets may be associated with low blood or plasma taurine concentrations and DCM in dogs. Taurine supplementation may result in prolonged survival times in these dogs, which is not typical for dogs with DCM. Samples should be submitted for measurement of blood and plasma taurine concentrations in dogs with DCM, and taurine supplementation is recommended while results of these analyses are pending.     

Effects of dietary fat and L-carnitine on plasma and whole blood taurine concentrations and cardiac function in healthy dogs fed protein-restricted diets

OBJECTIVE: To evaluate plasma taurine concentrations (PTC), whole blood taurine concentrations (WBTC), and echocardiographic findings in dogs fed 1 of 3 protein-restricted diets that varied in fat and L-carnitine content. ANIMALS: 17 healthy Beagles. DESIGN: Baseline PTC and WBTC were determined, and echocardiography was performed in all dogs consuming a maintenance diet. Dogs were then fed 1 of 3 protein-restricted diets for 48 months: a low-fat (LF) diet, a high-fat and L-carnitine supplemented (HF + C) diet, or a high-fat (HF) diet. All diets contained methionine and cystine concentrations at or above recommended Association of American Feed Control Officials (AAFCO) minimum requirements. Echocardiographic findings, PTC, and WBTC were evaluated every 6 months. RESULTS: The PTC and WBTC were not significantly different among the 3 groups after 12 months. All groups had significant decreases in WBTC from baseline concentrations, and the HF group also had a significant decrease in PTC. One dog with PT and WBT deficiency developed dilated cardiomyopathy (DCM). Taurine supplementation resulted in significant improvement in cardiac function. Another dog with decreased WBTC developed changes compatible with early DCM. CONCLUSIONS AND CLINICAL RELEVANCE: Results revealed that dogs fed protein-restricted diets can develop decreased taurine concentrations; therefore, protein-restricted diets should be supplemented with taurine. Dietary methionine and cystine concentrations at or above AAFCO recommended minimum requirements did not prevent decreased taurine concentrations. The possibility exists that AAFCO recommended minimum requirements are not adequate for dogs consuming protein-restricted diets. Our results also revealed that, similar to cats, dogs can develop DCM secondary to taurine deficiency, and taurine supplementation can result in substantial improvement in cardiac function.     

Evaluation of stabilized rice bran as an ingredient in dry extruded dog diets

The objectives of this research were to examine the palatability of stabilized rice bran (SRB) when included in a dry canine diet, and to determine the effects of SRB on food intake, digestion, fecal characteristics, blood lipid characteristics, and selected immune mediators. Experiment 1 tested the palatability of SRB. Diets contained poultry fat in Test 1 and soybean oil in Test 2, in conjunction with either 12% SRB or 12% defatted rice bran (DRB, as-fed basis), and were fed to 20 dogs. Diets contained approximately 32% protein and 22% fat (DM basis). Food intake data were collected and intake ratios calculated (grams of SRB diet consumed divided by total consumed of both diets). Intake ratios were 0.73 for Test 1 (P < 0.01) and 0.61 for Test 2 (P < 0.14) for SRB diets. Diets in Exp. 2 contained 12% SRB or DRB (as-fed basis), and poultry fat, beef tallow, or poultry fat:soybean oil (50:50) as the main fat sources, and were fed to 36 beagles. Diets contained approximately 32% protein and 22% fat (DM basis). The effects of SRB and DRB were determined on food intake, digestibility, fecal characteristics, and blood fatty acid, phospholipid, and eicosanoid concentrations. No differences were noted in food intake, digestibility, or fecal characteristics. Fat sources contributed much more to dietary fat than rice bran source; therefore, fat source profiles overwhelmed the rice bran source contribution. Dogs consuming a DRB diet had lower (P < 0.050) plasma phospholipid total monounsaturated fatty acids compared with those consuming a SRB diet (-1.17 vs. 0.95%, respectively), whereas plasma fatty acid concentrations tended (P < 0.119) to decrease more than with SRB diets. Total concentrations of red blood cell phospholipid SFA tended (P < 0.15) to be greater in dogs consuming a beef tallow-containing diet compared with those consuming a poultry fat or poultry fat:soybean oil diet. Total concentrations of red blood cell phospholipid PUFA and n-6 PUFA tended to be greater (P < 0.097 and P < 0.083, respectively) in dogs consuming a poultry fat-containing diet than in those consuming a beef tallow-containing diet. Statistical differences and tendencies were detected in individual plasma fatty acids and plasma and red blood cell phospholipids due to rice bran source, fat source, and their interaction. Eicosanoid concentrations did not change due to treatment. Stabilized rice bran is a highly palatable ingredient when included in a dry dog diet, and did not elicit an effect on inflammatory immune mediators in healthy dogs.     

Effects of dietary fiber supplementation on glycemic control in dogs with alloxan-induced diabetes mellitus.

The effect of a high insoluble-fiber (IF) diet containing 15% cellulose in dry matter, high soluble-fiber (SF) diet containing 15% pectin in dry matter, and low-fiber (LF) diet on glycemic control in 6 dogs with alloxan-induced insulin-dependent diabetes mellitus was evaluated. Each diet contained greater than 50% digestible carbohydrate in dry matter. A crossover study was used with each dog randomly assigned to a predetermined diet sequence. Each dog was fed each diet for 56 days. Caloric intake was adjusted weekly as needed to maintain each dog within 1.5 kg of its body weight measured prior to induction of diabetes mellitus. All dogs were given pork lente insulin and half of their daily caloric intake at 12-hour intervals. Mean (+/- SEM) daily caloric intake was significantly (P less than 0.05) less when dogs consumed the IF diet vs the SF and LF diets (66 +/- 3 kcal/kg, 81 +/- 5 kcal/kg, and 79 +/- 4 kcal/kg, respectively). Serum alkaline phosphatase activity was significantly (P less than 0.05) higher when dogs consumed the LF diet vs the IF and SF diets (182 +/- 37 IU/L, 131 +/- 24 IU/L, and 143 +/- 24 IU/L, respectively). Mean postprandial plasma glucose concentration measured every 2 hours for 24 hours, beginning at the time of the morning insulin injection, was significantly (P less than 0.05) lower at most blood sampling times in dogs fed IF and SF diets, compared with dogs fed the LF diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Taurine depletion and cardiovascular disease in adult cats fed a potassium-depleted acidified diet.

Although low plasma taurine concentrations have been associated with congestive cardiomyopathy in cats, the cause of taurine depletion in cats consuming adequate quantities of taurine is unknown. Taurine depletion and cardiovascular disease (cardiomyopathy and thromboembolism) developed unexpectedly in 3 of 6 healthy adult cats during a potassium-depletion study. Plasma taurine concentration decreased significantly (P less than 0.05) and rapidly over an 8-week period (from 98 to 36 nmol/ml) in 6 cats that consumed a potassium-deficient diet (0.20% potassium, dry matter basis) that was acidified with 0.8% ammonium chloride, despite containing dietary taurine concentrations (0.12% dry matter basis) in excess of amounts currently recommended. Taurine concentrations were significantly lower in cats fed the acidified diet than in 6 cats fed a potassium-deficient diet that was not acidified (36 nmol/ml vs 75 nmol/ml) after 8 weeks. In addition, plasma taurine concentrations did not decrease over a 6-month period in 8 cats that were fed a potassium-replete diet with acidifier. Plasma taurine concentrations were lowest in 3 cats that died of cardiovascular disease in the group receiving potassium-deficient, acidified diets. These data indicated an association between taurine and potassium balance in cats and suggested that development of taurine depletion and cardiovascular disease may be linked to concurrent potassium depletion.     

Effect of replacing barley with rice bran in finishing diet on productive performance and carcass characteristics of Afshari lambs

Thirty-five male Afshari lambs (3.5 months old), with an average weight of 35 kg were randomly assigned to one of five experimental treatments relating to optimal replacement level of rice bran in lamb finishing diets. The lambs were fed a milled concentrate (3 mm screen) diet supplemented with 15% (DM basis) chopped (5 cm length) lucerne hay and chopped (5 cm length) maize silage or wet (80% moisture) sugar beet pulp. Barley grain in the lambs’ diets was replaced by rice bran at either 0, 15, 30, 45 or 60% of the concentrate mixture on a dry matter basis. Results show that lambs fed 45 and 60% rice bran treatments weighed significantly less than those fed with 15 and 30% and control group (P < 0.05). Average daily gain in lambs fed with concentrate mixtures containing 45 and 60% rice bran were 33 and 47% lower than control, respectively (P < 0.05). Lambs that received diets containing 45 and 60% rice bran, had lower feed intake (P < 0.05) than other groups. Using rice bran in the finishing diet had no significant effect on dressing percentage, tail percentage, abdominal fat and visceral organ weights. These results suggest that barley can be replaced with rice bran up to 30% in the finishing diets of lambs without any adverse effect on lamb performance.     

Comparison of the efficacy of two anti-uric acid diets in dalmatian dogs.

Commercial anti-uric acid diets for dogs may contain insufficient protein to sustain growth and lactation. In order to investigate the efficacy of an experimental purine-free diet moderately low in protein, its effect on urinary uric acid excretion was compared with that of a commercial dog food and a commercial low-protein anti-uric acid diet. The experimental diet, commercial dog food and commercial anti-uric acid diet contained 10.0, 12.8 and 5.0 g crude protein/MJ metabolizable energy, respectively. Twelve Dalmatian dogs were subjected to a 3 x 3 Latin square study. Although the plasma uric acid concentration was significantly lower when the dogs were fed either the commercial anti-uric diet (18.7 +/- 6.0 mumol/l, mean +/- SD, n = 12) or the experimental diet (19.2 +/- 8.3 mumol/l), when compared to the commercial dog food (29.2 +/- 11.1 mumol/l), no significant decrease of uric acid concentration in urine collected before the morning meal was seen. The average concentration of urinary uric acid was 60 mumol/l. There was a significant increase in the urea:creatinine ratio in urine when the dogs were fed the experimental diet compared to the commercial anti-uric acid diet, confirming that the experimental diet contained more protein. The experimental diet lowered plasma uric acid and was relatively high in protein and thus may be suitable for use in growing and lactating dogs to prevent ammonium urate urolithiasis.     

Effects of phosphorus/calcium-restricted and phosphorus/calcium-replete 32% protein diets in dogs with chronic renal failure.

Twenty-four dogs with induced, severe chronic renal failure were allotted to 2 groups of 12 each. Group-A dogs were fed a 0.4% phosphorus (P)/0.6% calcium, 32% protein diet, and group-B dogs were fed a 1.4% P/1.9% calcium, 32% protein diet. Dogs were studied over 24 months to determine clinical status, survival, blood biochemical alterations, glomerular filtration rate (GFR), urinary excretion of P and protein, renal morphologic changes, and renal tissue concentrations of calcium, P, and magnesium. Group-A dogs developed statistically significant differences from group-B dogs in several blood biochemical values (PCV and total solids, calcium, P, potassium, sodium, chloride, total CO2 (TCO2), anion gap, and parathyroid hormone concentrations) and in urinary P excretion. Mean (+/- SEM) GFR values in group-A and group-B dogs were nearly identical when diets were initiated (group A = 0.73 +/- 0.05 ml/min/kg of body weight; group B = 0.72 +/- 0.08 ml/min/kg), but significantly (P = 0.0346) lower GFR developed in group-B than in group-A dogs over time. At 24 months, GFR in survivors was 0.83 +/- 0.08 and 0.63 +/- 0.15 ml/min/kg for dogs of groups A and B, respectively. Other measurements favored the hypothesis that P/calcium restriction was beneficial, but values failed to reach statistical significance. Survival was greater at 24 months in group-A than in group-B (7 vs 5) dogs, and renal tissue concentrations of calcium and P were higher in group-B than in group-A dogs. Differences were not detected between groups in urinary excretion of protein and in the type or severity of renal lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma thyroid hormone concentrations in dogs competing in a long-distance sled dog race

Plasma thyroxine (T4), 3,5,3'-triiodothyronine (T3), total protein, and albumin concentrations were measured in 15 dogs both before and after completion, and in an additional 16 dogs before and 24 dogs after completion, of a long-distance sled dog race. The plasma T4 concentration (mean +/- SD) decreased significantly from 18.2 +/- 5.4 nmol/L before to 14.3 +/- 3.5 nmol/L after the race in dogs evaluated at both times and decreased significantly from 21.8 +/- 10.5 nmol/L before to 15.8 +/- 4.9 nmol/L after the race in dogs sampled only before or only after the race. The mean plasma T3 concentrations in dogs measured twice decreased significantly from 1.20 +/- 0.48 nmol/L before to 0.74 +/- 0.42 nmol/L after the race, as well as in dogs measured either before (1.28 +/- 0.36 nmol/L) or after (0.69 +/- 0.28 nmol/L) the race, respectively. Plasma total protein and albumin concentrations decreased significantly after completion of the race. No significant change was noted in 4 control dogs that did not compete in the race and were tested during a similar time period. The plasma concentrations of T4 and T3 were lower than the normal reference range established for this laboratory in 23 and 39%, respectively, of Alaskan sled dogs tested before the race. Plasma thyroid hormone concentrations frequently are below normal in conditioned Alaskan sled dogs and are further reduced after prolonged submaximal exercise.     

Effect of dietary fat on oral bioavailability of tepoxalin in dogs

A pharmacokinetic study was conducted to compare the oral bioavailability of tepoxalin and its pharmacologically active acid metabolite in fasted dogs and dogs fed either a low-fat or high-fat commercial diet. Using a cross-over design, six beagles were administered tepoxalin (10 mg/kg) intravenously (i.v.) and orally (p.o.) after being fed one of three diets (fasted, low-fat, or high-fat). Thereafter, blood samples were collected at frequent intervals, concentrations of tepoxalin and acid metabolite in plasma were determined by high performance liquid chromatography, and pharmacokinetic parameters were estimated. After i.v. dosing, the mean (+/-SD) half-life of elimination (t(1/2(beta))) was 2.45 +/- 1.47 h. After p.o. administration, plasma concentrations of acid metabolite were consistently higher than corresponding concentrations of the parent tepoxalin, indicating that tepoxalin is subject to a substantial first-pass effect. Mean (+/-SD) peak concentrations of tepoxalin were significantly higher after feeding of low-fat (1.08 +/- 0.37 microg/mL) and high-fat (1.19 +/- 0.29 microg/mL) diets than in fasted dogs (0.53 +/- 0.20 microg/mL), suggesting that feeding improves oral bioavailability.     

Evaluation of selected high-starch flours as ingredients in canine diets.

Cereal grains represent 30 to 60% of the DM of many companion animal diets. Once incorporated into a diet, the starch component of these grains can provide an excellent source of ME. However, crystallinity and form of starch are variable and can cause incomplete digestion within the gastrointestinal tract. Diets fed in this experiment included one of six high-starch flours as the main source of carbohydrate. The flours originated from barley, corn, potato, rice, sorghum, and wheat. The diets were extruded and kibbled. Starch fraction concentrations of flours consisted of nearly 100% rapidly digestible starch (RDS) and slowly digestible starch (SDS) combined. Starch fraction concentrations of diets paralleled concentrations in flours. Flours varied widely in concentrations of CP, fat, starch, and total dietary fiber. Ileal OM and CP digestibilities were lowest for the potato flour treatment (74 and 64%, respectively). Ileal and total tract starch digestibilities were different (P<.05) among treatments; however, the starch component of all diets was nearly completely digested (>99%). Total tract digestibility of DM and OM was lowest for sorghum (80 and 84%, respectively) compared to all other diets. Crude protein digestibility was highest for corn (87%). Wet fecal weights tended (P<.08) to be greatest for dogs fed the barley treatment (175 g/d). However, dry fecal weights (dried at 55 degrees C) were greatest for dogs consuming the sorghum diet (51 g/d). Fecal scores were consistently greater (i.e., looser stools) for the barley treatment. Any of these flours could be used without negative effects on digestion at either the ileum or in the total tract. Fecal consistency data for dogs consuming the barley treatment indicate that diets containing large amounts (>50%) of barley may not be advantageous for dog owners who house their animals indoors for most of the day.     

Glycaemic and insulinaemic responses to mechanical or thermal processed barley in horses

This study was conducted to evaluate the effects of different barley processing techniques on the glycaemic and insulinaemic responses in horses. It was hypothesized that the changes in pre-caecal starch digestibility caused by barley processing would affect metabolic responses. Six horses were fed in random order: whole (WB), finely ground (FGB), steamed (SB), steam-flaked (SFB) and popped barley (PB). The total barley intake was adjusted to 630 g starch/horse/day (1.2-1.5 g starch/kg BW/day). During a 10-day stabilization period, the horses also received 6 kg grass hay/horse/day. On the blood collection day, the horses were fed their test diet (exclusively barley), and blood samples were taken at defined times for glucose and insulin analysis. The degree of starch gelatinization (DG) in the untreated or thermally processed barley was analysed using the glucoamylase method. In general, barley feeding resulted in a significant increase in mean plasma glucose and insulin concentrations within 30-45 min after feeding. While the highest glucose and insulin responses occurred after intake of SFB with a DG of 28.7%, the changes in glucose and insulin were more pronounced with PB with a DG of 95.6%, with SB (DG: 22.2%), FGB (DG: 14.9%) and WB (DG: 14.9%). The peak plasma glucose varied between 5.72 +/- 0.67 mmol/l with FGB and 6.52 +/- 0.64 mmol/l with SFB (treatment p < 0.05). These results confirm the post-prandial changes in plasma glucose and insulin after intake of the different barley products, but also show that there was no association of the highest degree of gelatinization in the different barley diets with the most pronounced glycaemic or insulinaemic response.     

Influence of obesity on plasma lipid and lipoprotein concentrations in dogs

OBJECTIVE: To determine effects of obesity and diet in dogs on plasma lipid and lipoprotein concentrations by assaying plasma leptin and ghrelin concentrations and determining total plasma cholesterol and triglyceride concentrations as well as the concentrations of cholesterol and triglycerides in various lipoprotein classes (ie, very-low-density, low-density, and high-density lipoproteins). ANIMALS: 24 Beagles; 12 lean (mean [+/- SEM] body weight, 12.7 +/- 0.7 kg) and 12 chronically obese (21.9 +/- 0.8 kg) dogs of both sexes, between 1 and 9 years old. PROCEDURES: Total plasma cholesterol and triglyceride concentrations; lipoprotein cholesterol and triglyceride concentrations; and plasma ghrelin, leptin, free fatty acids, insulin, and glucose concentrations were measured and compared between lean and obese dogs, both of which were fed a complete and balanced maintenance diet. Chronically obese dogs were subsequently fed a high-protein low-energy diet to evaluate effects of diet composition on plasma lipid and lipoprotein measurements. RESULTS: Chronic obesity resulted in a significant decrease in plasma ghrelin concentration and a significant increase in plasma leptin, cholesterol, and triglyceride concentrations in dogs. High total plasma cholesterol and triglyceride concentrations resulted from increased cholesterol and triglyceride concentrations in all lipoprotein fractions. In obese dogs, modification of diet composition resulted in beneficial effects on plasma lipid and leptin concentrations, even before weight loss was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Correlations exist between obesity and plasma measurements (ie, lipoproteins, leptin, insulin, and ghrelin) commonly associated with obesity. Modification of diet composition to control energy intake improves plasma lipid and leptin concentrations in obese dogs.     

Myocardial taurine concentrations in cats with cardiac disease and in healthy cats fed taurine-modified diets.

Myocardial taurine concentrations were measured in cats with cardiac disease and in healthy cats fed diets with various concentrations of taurine. Group 1 was composed of 26 cats with 3 categories of naturally developing cardiac disease: dilatative cardiomyopathy (group 1A), 10 cats; hypertrophic cardiomyopathy (group 1B), 9 cats; and volume overload (group 1C), 7 cats. These cats had been fed various commercial diets. Group 2 was composed of 40 healthy cats that had been fed diets varying in taurine concentration (0 to 1% taurine) for at least 2 years. Mean myocardial taurine concentrations did not differ significantly between group-1 cats with dilatative cardiomyopathy and those with hypertrophic cardiomyopathy or volume overload. Cats in group 1A had a mean myocardial taurine concentration 3 times higher than healthy cats fed a taurine-free diet (P less than 0.002). Mean myocardial taurine concentrations did not differ significantly between group-1A cats and healthy cats fed a diet containing 0.02% taurine; group-1A cats had significantly lower mean myocardial taurine concentrations than did healthy cats fed a synthetic diet containing 0.05 or 1.0% taurine (P less than 0.001). Acute oral administration of taurine in 5 group-1A cats appeared to increase mean myocardial taurine concentrations, compared with similar cats not given taurine during treatment for cardiac failure. In group-2 cats, mean myocardial taurine concentrations increased directly with percentage of dietary taurine.     

Dietary hyperthyroidism in dogs

Objectives: Evaluation of dogs with elevated plasma thyroxine concentration fed raw food before and after changing the diet. Method: Between 2006 and 2011 all dogs presented with an elevated plasma thyroxine concentration and a dietary history of feeding raw food were included. Thyroxine (reference interval: 19·3 to 51·5 nmol/L) and in many cases also thyroid-stimulating hormone concentrations (reference interval: <0·30 ng/mL) were measured initially and after changing the diet. Results: Twelve dogs were presented with a median age of five years. The median plasma thyroxine concentration was 156·1 (range of 79·7 to 391·9) nmol/L; in six dogs, thyroid-stimulating hormone concentration was measured and was <0·03 ng/mL in five dogs and 0·05 ng/mL in one dog. Six dogs showed clinical signs such as weight loss, aggressiveness, tachycardia, panting and restlessness while six dogs had no clinical signs. After changing the diet eight dogs were examined: thyroxine concentration normalised in all dogs and clinical signs resolved. Clinical Significance: Dietary hyperthyroidism can be seen in dogs on a raw meat diet or fed fresh or dried gullets. Increased plasma thyroxine concentration in a dog, either with or without signs of hyperthyroidism, should prompt the veterinarian to obtain a thorough dietary history.     

Influence of dietary composition on gastric emptying and motility in dogs: potential involvement in acute gastric dilatation

Gastric dilatation-volvulus is a dramatic and life-threatening disease of large-breed dogs. The cause is unknown, but ingestion of dry cereal-based food is frequently incriminated as a predisposing factor. The purpose of this study was to examine the effect of commercial diets on gastric motility and emptying in the dog. Four large-breed dogs were fed 3 different diets (diet A = canned meat-based; B = cereal-based with 77% added water; and C = dry cereal-based) in a randomized block design. Each experiment was done in triplicate. Motility was assessed, using 5 AgAgCl electrodes and 2 strain gauges sutured along the serosa of the stomach and proximal duodenum. Dogs were fed at the same time each day and the time to change from the fed to the fasted pattern of gastrointestinal motility (changeover) was measured. Gastric emptying was assessed by recording gastric radioactivity. After feeding a meal mixed with 99mTc-labeled resin, the log of activity was plotted against time, and the half-time of gastric emptying (t1/2 GE) was calculated. Mean (+/- SEM) times from feeding to changeover for the 3 diets were: diet A, 9.7 +/- 0.9; B, 10.5 +/- 0.4; and C, 11.0 +/- 0.8 hours. Diet had minimal influence on the half time of gastric emptying (diet A, 2.2 +/- 0.3; B, 2.6 +/- 0.4; and C, 2.9 +/- 0.3 hours; P greater than 0.05). The data indicate that gastric motility and emptying in healthy large-breed dogs were not affected by dietary composition. Because most large dogs are fed cereal-based food for reasons of cost and ease of use, these diets may have been wrongly incriminated as a predisposing factor in gastric dilatation-volvulus.     

Plasma Taurine Concentrations in Normal Dogs and in Dogs With Heart Disease

Plasma taurine concentrations were determined in 76 dogs with dilated cardiomyopathy (DCM), 28 dogs with acquired valvular disease (AVD), and 47 normal (control) dogs. The data were collected at 2 referral centers. The Animal Medical Center, New York, NY (AMC), and the University of California, Davis (UCD), and the studies were conducted independently. Different anticoagulants (sodium citrate at AMC and lithium heparin at UCD) were used to collect the plasma samples. Paired analysis of samples showed a significant difference in plasma taurine concentrations, depending on the anticoagulant used. Consequently, results from each clinic were analyzed separately. Plasma taurine concentrations were significantly higher in dogs with AVD (median, 133 nmol/mL; range, 25 to 229 nmol/mL) than in control dogs (median, 63 nmol/mL; range 44 to 224 nmol/mL) and dogs with DCM (median, 72 nmol/mL; range, 1 to 247 nmol/mL) at AMC (P= .001). The number of dogs with AVD at UCD was too small to draw meaningful conclusions. At UCD, the median plasma taurine concentration was 98 nmol/mL (range, 28–169 nmol/mL) in dogs with AVD, 75 nmol/mL (range, 0.1–184 nmol/mL) in dogs with DCM, and 88 nmol/mL (range 52–180 nmol/mL) in control dogs. There were no significant differences in plasma taurine concentrations between dogs with DCM and the control dogs at either hospital. Congestive heart failure and administration of cardiac medication had no significant effect on plasma taurine concentrations. Plasma taurine concentration was low (<25 nmol/mL) in 17% (13/76) of the dogs with DCM. Seven of the 13 dogs with low plasma taurine concentrations were Cocker Spaniels or Golden Retrievers. It was concluded that most dogs with DCM do not have low plasma taurine concentrations. However, certain breeds or individual dogs may have low plasma taurine concentrations in association with DCM. Whether this association is causal or not is unknown. The significance of the high plasma taurine concentrations in dogs with AVD is also unknown.     

Evaluation of cats fed vegetarian diets and attitudes of their caregivers

OBJECTIVE: To determine motivation and feeding practices of people who feed their cats vegetarian diets as well as taurine and cobalamin status of cats consuming vegetarian diets. DESIGN: Cross-sectional study. ANIMALS: 34 cats that had been exclusively fed a commercial or homemade vegetarian diet and 52 cats that had been fed a conventional diet for > or = 1 year. PROCEDURES: Participants were recruited through a Web site and from attendees of a national animal welfare conference. Caregivers of cats in both groups answered a telephone questionnaire regarding feeding practices for their cats. Blood was obtained from a subset of cats that had been fed vegetarian diets. Blood and plasma taurine and serum cobalamin concentrations were measured. RESULTS: People who fed vegetarian diets to their cats did so largely for ethical considerations and were more likely than people who fed conventional diets to believe that there are health benefits associated with a vegetarian diet and that conventional commercial cat foods are unwholesome. Both groups were aware of the potential health problems that could arise from improperly formulated vegetarian diets. All cats evaluated had serum cobalamin concentrations within reference range, and 14 of 17 had blood taurine concentrations within reference range. CONCLUSIONS AND CLINICAL RELEVANCE: Vegetarian diets are fed to cats primarily for ethical considerations. Results of this study should aid practitioners in communicating with and providing advice to such clients.