Effects of diet on fecal occult blood testing in healthy dogs.

Six dogs were fed each of nine diets to evaluate the effects of diet on fecal occult blood test results. The diets represented a range of different type (i.e. canned, dry or semi-moist), protein and vegetable constituents, and fiber contents. Each diet was fed twice daily for five consecutive days; fecal samples were collected twice daily on days 4 and 5. An o-tolidine test kit and a guaiac paper test kit for fecal occult blood were used. Two hundred and sixteen fecal samples were analyzed (24 samples/diet). When using the guaiac test the following positive results were obtained from fecal samples from dogs consuming a canned meat- and vegetable-based diet (24/24 samples); a canned meat-based diet (24/24 samples); a dry corn and poultry-based diet (9/24 samples); a dry corn, wheat, and meat meal diet (4/24 samples), a canned poultry-based diet (1/24 sample) and a semi-moist soybean meal-based diet (2/24 samples). A total of 64 samples were positive using the guaiac test. Using the o-tolidine test, no samples were positive. The difference between the number of positive results with each test kit was highly significant (p < 0.001). Results indicate that 1) diet affects the specificity of guaiac test fecal occult blood results in the dog and 2) positive o-tolidine test results were not caused by diets fed in the study.     

Effect of vaccination on fecal cortisol metabolites in cats and dogs

The aim of this study was to apply a cortisol metabolite determination in the faeces of cats and dogs for monitoring disturbances. In this experiment faeces from every spontaneous defecation of 10 cats and 10 dogs (5 of each sex) were collected starting from one day before until two days after the yearly vaccination. Concentrations of 11,17-dioxoandrostanes (cat) and cortisol equivalents (dog) were determined by enzyme immunoassay (EIA). Faecal cortisol metabolites increased and reached peak concentrations (median: 412% in cats and 417% in dogs, respectively above baseline values) in one of the next two samples following the vaccination. This indicated an activation of the adrenocortex, the degree to which the different parts (physical and psychological components) of the whole vaccination procedure contributed to it was not evaluated. From this experiment we conclude that measuring cortisol metabolites in the faeces is a non-invasive method to monitor stressful conditions in cats and dogs and thus is a valuable tool for evaluating animal welfare.     

Prevalence and factors associated with fecal shedding of Giardia spp. in domestic cats

The prevalence of cats shedding Giardia cysts (13.6%) in the present study was found to be higher than previously reported (1% to 11%) and may reflect a higher sensitivity for the diagnostic test used. The presence of Cryptosporidium spp. oocysts, coccidial oocysts, and a clinical history of chronic (>2 weeks) gastrointestinal signs were significantly associated with the presence of Giardia spp. cysts in the feces. There were no associations between the presence of Giardia spp. cysts and type of housing, acute gastrointestinal signs, vomiting, gender, source of cat (i.e., animal shelter versus private breeder), or gastrointestinal parasites other than Cryptosporidium spp. and intestinal coccidial agents.     

Evaluation of dietary and environmental risk factors for hyperthyroidism in cats

OBJECTIVE: To identify dietary and environmental risk factors for hyperthyroidism in cats. DESIGN: Case-control study. ANIMALS: 100 cats with hyperthyroidism and 163 control cats. PROCEDURE: Medical records were examined, and owners completed a mailed questionnaire. Data collected included information regarding demographic variables, environmental exposures, and diet, including preferred flavors of canned cat food. RESULTS: Case cats were significantly less likely to have been born recently than control cats. Housing; exposure to fertilizers, herbicides, or plant pesticides; regular use of flea products; and presence of a smoker in the home were not significantly associated with an increased risk of disease, but cats that preferred fish or liver and giblets flavors of canned cat food had an increased risk. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cats that prefer to eat certain flavors of canned cat food may have a significantly increased risk of hyperthyroidism.     

Occurrence of occult bacteriuria in healthy cats

Knowledge of the occurrence of bacteriuria in adult, healthy cats is scarce in the scientific literature. A study was designed to investigate the occurrence of bacteriuria in healthy cats without current or previous signs of lower urinary tract disease. The study included 108 cats, 53 males (49.5%) and 55 females (50.5%). The cats ranged in age between 7 months and 18 years, with a mean age of 4.4 years and a median age of 4.0 years. Urine was obtained by cystocentesis from all the cats, and was submitted for bacteriological analyses. Urine and urine sediment was cultured on separate blood agar plates for quantification and species identification by standard procedures. Detection of ≥10(3)colony forming units (cfu) per ml urine was defined as significant bacteriuria. Significant bacteriuria exceeding 10(5) cfu/ml was detected in one sample with a combination of Enterococcus species and Staphylococcus species. There was no bacterial growth in the urine samples from 107 cats (99.1%). Results from our study indicate that the prevalence of bacteriuria in clinically healthy, adult cats is low. Also, that contamination of samples is rare when urine is collected by cystocentesis.     

Effect of low levels of dietary tyrosine on the hair colour of cats

Experiments were conducted to investigate the basis for the change in hair colour of black cats to reddish-brown. Black cats were given purified diets based on gelatin, casein plus lactalbumin, or crystalline amino acids as protein sources. Diets that caused the colour of hair to change to reddish-brown were associated with a reduction in melanin in hair (observed by direct microscopic examination), a decreased total melanin concentration and low concentrations of tyrosine in plasma. Reddish hair coat was induced in black kittens born to queens given a tyrosine-deficient diet during pregnancy. Black hair colour was maintained or restored by diets containing a high concentration of tyrosine or phenylalanine. Current dietary recommendations for dietary tyrosine and phenylalanine for cats are below those required to support maximal melanin synthesis in black cats. The requirement appears to be greater than a combination of 4.5 g tyrosine plus 12 g phenylalanine/kg diet but less than 24 g phenylalanine alone/kg diet.     

Effect of diet on results obtained by use of two commercial test kits for detection of occult blood in feces of dogs.

To evaluate the effect of diet on results obtained by use of 2 commercial test kits for detection of occult blood in feces, 5 dogs were fed 7 diets in randomized sequence. Dry and canned diets with various principal ingredients were evaluated. Each diet was offered twice over a 24-hour period, followed by a 36-hour nonfeeding period. Fecal specimens were collected twice daily, and tests for occult blood were performed within 12 hours. The dietary origin of fecal specimens was confirmed by use of colored markers fed with each diet, and was correlated with estimates of gastrointestinal tract transit time. A modified guaiac paper test and an o-tolidine tablet test were performed on each specimen. Of 59 specimens, 4 were positive for occult blood, using the o-tolidine tablet test. Three positive results were associated with a mutton-based canned diet, and 1 positive result was associated with a canned beef-based diet. Of 59 specimens, 11 were positive for occult blood, using the modified guaiac paper test. Four positive results were associated with the mutton diet, and 3 positive results were associated with the beef diet. Of the remaining 5 diets, 4 caused 1 positive reaction. Results were inconsistent with the null hypothesis that the distribution of positive occult blood test results is not affected by diet (P < 0.025), and indicate that diet can affect the specificity of peroxidase-based tests for detection of occult blood in canine feces. Diet modification prior to testing is recommended.     

Association between dietary factors and calcium oxalate and magnesium ammonium phosphate urolithiasis in cats.

OBJECTIVE: To identify dietary factors associated with the increase in occurrence of calcium oxalate (CaOx) uroliths and the decrease in occurrence of magnesium ammonium phosphate (MAP) uroliths in cats. DESIGN: Case-control study. ANIMALS: 173 cats with CaOx uroliths, 290 cats with MAP uroliths, and 827 cats without any urinary tract diseases. PROCEDURE: Univariate and multivariate logistic regression were performed. RESULTS: Cats fed diets low in sodium or potassium or formulated to maximize urine acidity had an increased risk of developing CaOx uroliths but a decreased risk of developing MAP uroliths. Additionally, compared with the lowest contents, diets with the highest moisture or protein contents and with moderate magnesium, phosphorus, or calcium contents were associated with decreased risk of CaOx urolith formation. In contrast, diets with moderate fat or carbohydrate contents were associated with increased risk of CaOx urolith formation. Diets with the highest magnesium, phosphorus, calcium, chloride, or fiber contents and moderate protein content were associated with increased risk of MAP urolith formation. On the other hand, diets with the highest fat content were associated with decreased risk of MAP urolith formation. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that diets formulated to contain higher protein, sodium, potassium, moisture, calcium, phosphorus, and magnesium contents and with decreased urine acidifying potential may minimize formation of CaOx uroliths in cats. Diets formulated to contain higher fat content and lower protein and potassium contents and with increased urine acidifying potential may minimize formation of MAP uroliths.     

Influence of dietary source of phosphorus on fecal and urinary excretion of phosphorus and other minerals by male cats

Twelve male cats were fed 2 diets that differed in the source of P. In diet 1 (1.4% P), 62.7% of P originated from poultry, meat, and fish meal, and the remainder from other organic ingredients of food. In diet 2 (1.6% P), 63.5% of P was derived from neutral monobasic/dibasic salts, and the remainder from other organic ingredients of the food. The P intake was nearly the same with both diets, but there was a significant (P less than 0.05) difference between diets in the percentage of ingested P that was excreted in the urine (14.7 +/- 5.3% for diet 1; 34.9 +/- 8.4% for diet 2), and in 6-day urinary P excretion (774 +/- 290 mg for diet 1; 2,004 +/- 556 mg for diet 2). The P concentrations in urine samples obtained by cystocentesis after cats ate were significantly (P less than 0.05) higher when cats were fed diet 2 than when those same cats were fed diet 1. Plasma P concentrations increased after ingestion of diet 2, but were unchanged after ingestion of diet 1. Seemingly, urinary excretion of P was markedly influenced by dietary composition. Diets with the same P content have potential for different biologic effects because of differences in availability of P.     

Effect of dietary soy on serum thyroid hormone concentrations in healthy adult cats

OBJECTIVE: To compare effects of short-term administration of a soy diet with those of a soy-free diet on serum thyroid hormone concentrations in healthy adult cats. ANIMALS: 18 healthy adult cats. PROCEDURE: Cats were randomly assigned to receive either a soy or soy-free diet for 3 months each in a crossover design. Assays included CBC, serum biochemical profile, thyroid hormone analysis, and measurement of urinary isoflavone concentrations. RESULTS: Genistein, a major soy isoflavone, was identified in the urine of 10 of 18 cats prior to dietary intervention. Compared with the soy-free diet, cats that received the soy diet had significantly higher total thyroxine (T4) and free T4 (fT4) concentrations, but unchanged total triiodothyronine (T3) concentrations. The T3/fT4 ratio was also significantly lower in cats that received the soy diet. Although the magnitudes of the increases were small (8% for T4 and 14% for fT4), these changes resulted in an increased proportion of cats (from 1/18 to 4/18) that had fT4 values greater than the upper limit of the laboratory reference range. There was no significant effect of diet on any other measured parameter. CONCLUSIONS AND CLINICAL RELEVANCE: Short-term administration of dietary soy has a measurable although modest effect on thyroid hormone homeostasis in cats. Increase in T4 concentration relative to T3 concentration may result from inhibition of 5'-iodothyronine deiodinase or enhanced T3 clearance. Soy is a common dietary component that increases serum T4 concentration in cats.     

Effect of dietary phosphoric acid supplementation on acid-base balance and mineral and bone metabolism in adult cats.

Experimental evidence indicates that maintenance of urinary pH < or = 6.4 is the single most effective means of preventing feline struvite crystalluria or urolithiasis of noninfectious causes. This may be accomplished by dietary acidification, but must be moderated to avoid potential adverse effects of excessive acidification, including bone demineralization, negative calcium balance, potassium depletion, and renal disease. Effects of chronic dietary phosphoric acid supplementation on acid-base balance and on mineral and bone metabolism were investigated in adult, domestic cats. One group of 6 cats was fed a basal, naturally acidifying diet without added acidifiers, and another group of 6 cats was fed 1.7% dietary phosphoric acid. Changes observed during 12 months of study included development of noncompensated metabolic acidosis, increased urinary calcium excretion, and lower but positive calcium balance in cats of both groups. Urinary pH decreased in cats of both groups, but was significantly (P < 0.05) and consistently maintained < or = 6.4 in cats given dietary phosphoric acid. Urinary phosphorus excretion increased in cats of both groups, but was significantly (P < 0.05) greater in phosphoric acid-supplemented cats, leading to lower overall phosphorus balance as well. Potassium balance decreased in cats of both groups, but was only transiently negative in the phosphoric acid-supplemented cats midway through the study, and normalized at positive values thereafter. Plasma taurine concentration was not affected by dietary acidification, and remained well within the acceptable reference range for taurine metabolism. Double labeling of bone in vivo with fluorescent markers was followed by bone biopsy and histomorphometric measurement of several static and dynamic variables of bone formation. Overall indices of bone formation decreased in cats of both groups with age and confinement, but were not affected by dietary phosphoric acid supplementation. Dietary supplementation with phosphoric acid used as the principal inorganic P source to achieve moderate and stable degree of urinary acidification, did not appear over the course of 1 year, to have induced adverse effects on mineral, bone, or taurine balance in these adult domestic cats.     

Effects of dietary cysteine on blood sulfur amino acid, glutathione, and malondialdehyde concentrations in cats

OBJECTIVE: To determine effects of dietary cysteine on blood sulfur amino acids (SAA), reduced glutathione (GSH), oxidized glutathione (GSSG), and malondialdehyde (MDA) concentrations in cats. ANIMALS: 12 healthy adult cats. PROCEDURE: Cats were fed diets with a nominal (0.50 g/100 g dry matter [DM]), moderate (1.00 g/100 g DM), or high (1.50 g/100 g DM) cysteine content in a 3 X 3 Latin square design with blocks of 8 weeks' duration. Venous blood samples were collected after each diet had been fed for 4 and 8 weeks, and a CBC and serum biochemical analyses were performed; poikilocyte, reticulocyte, and Heinz body counts were determined; and MDA, GSH, GSSG, and SAA concentrations were measured. RESULTS: Blood cysteine and MDA concentrations were not significantly affected by dietary cysteine content. Blood methionine, homocysteine, and GSSG concentrations were significantly increased when cats consumed the high cysteine content diet but not when they consumed the moderate cysteine content diet, compared with concentrations obtained when cats consumed the nominal cysteine content diet. Blood GSH concentrations were significantly increased when cats consumed the moderate or high cysteine content diet. CONCLUSIONS: Increased dietary cysteine content promotes higher blood methionine, homocysteine, GSH, and GSSG concentrations in healthy cats. CLINICAL RELEVANCE: Supplemental dietary cysteine may be indicated to promote glutathione synthesis and ameliorate adverse effects of oxidative damage induced by disease or drugs.     

Plasma histamine concentration and histamine detection in peripheral blood eosinophils in cats

Plasma histamine levels were measured in 11 clinically healthy cats and 15 cats with allergic dermatitis. Histamine levels were markedly elevated in 5/15 allergic cats. A calcium ionophore, A23187, stimulates histamine release from feline peripheral blood cells. Immunostaining of blood smears from clinically healthy cats revealed that approximately 10% of eosinophils possessed histamine-containing granules. These results indicate that some peripheral eosinophils in cats contain histamine and can release histamine by appropriate stimulation.     

Effect of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus

OBJECTIVE: To evaluate effects of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus. DESIGN: Randomized controlled crossover trial. ANIMALS: 16 cats with naturally acquired diabetes mellitus. PROCEDURE: Cats were fed a diet high in insoluble fiber (HF) containing 12% cellulose (dry-matter basis) or a diet low in insoluble fiber (LF) for 24 weeks; they were fed the other diet for the subsequent 24 weeks. Caloric intake and insulin treatment were adjusted to maintain stable body weight and control of glycemia, respectively. Cats were allowed an adaptation period of 6 weeks after initiation of a diet, after which control of glycemia was evaluated at 6-week intervals for 18 weeks. Variables assessed included serum glucose concentration measured during the preprandial state, blood glycated hemoglobin concentration, serum glucose concentration measured at 2-hour intervals for 12 hours beginning at the time of the morning insulin injection, 12-hour mean serum glucose concentration, and mean fluctuation in serum glucose concentration from the 12-hour mean serum glucose concentration. RESULTS: Mean daily caloric intake, body weight, or daily insulin dosage did not differ significantly between cats when fed HF and LF diets. Mean preprandial serum glucose concentration, most post-prandial serum glucose concentrations, and the 12-hour mean serum glucose concentration were significantly lower when cats consumed the HF diet, compared with values when cats consumed the LF diet. CONCLUSIONS AND CLINICAL RELEVANCE: These results support feeding a commercially available diet containing approximately 12% insoluble fiber (dry-matter basis) to cats with naturally acquired diabetes mellitus.     

Effect of dietary factors on the responses of chicks to corticosterone injections

Corticosterone-injected chicks fed on a diet based on sorghum gained less weight and accumulated more hepatic fat than chicks treated similarly and fed on a diet based on maize. The retention of nitrogen and dry matter and the apparent metabolisable energy of these diets were not affected by type of grain, either in corticosterone-injected or in untreated birds. A slight methionine deficiency in the maize diet resulted in an additional increase in the concentration of hepatic lipids in corticosterone-injected chicks. However, hepatic lipid concentration was not affected by either a deficiency or an excess of methionine in the diet based on sorghum. The dietary fat concentration of isocaloric and isonitrogenous diets and the energy concentration of diets containing similar energy-to-protein ratios did not affect the response of the chicks to corticosterone. There was a negative correlation between the relative weight gain of corticosterone-treated chicks and the relative hepatic fat content. The latter was positively correlated with relative abdominal fat pad size.     

Evaluation of two commercial test kits for detection of occult blood in feces of dogs

To evaluate the sensitivity and specificity of 2 commercial test kits for detection of occult blood in canine feces, various volumes of blood were administered to 6 dogs via orogastric tube. Blood volumes tested were chosen on the basis of hemoglobin quantities of 5, 10, 20, 200, 350, and 500 mg of hemoglobin/kg of body weight. Fecal specimens were collected twice daily and analyzed separately by 2 observers for the presence of occult blood by use of modified guaiac and orthotolodine tablet tests, and for melena by visual inspection. Five dogs given blood at the rate of 500 mg of hemoglobin/kg and 1 dog given blood at the rate of 350 mg of hemoglobin/kg developed melena. Results of both occult blood tests were positive in 2 of 6 dogs given blood at the rate of 5 mg of hemoglobin/kg. Five of 6, and 4 of 6 dogs given blood at the rate of 10 mg hemoglobin/kg had positive test results by modified guaiac and orthotolodine methods, respectively. Results of both methods were positive in all dogs given blood at the rate of 20 mg of hemoglobin/kg. There was 86% agreement between the 2 observers' results for the modified guaiac method, and 78% agreement for the orthotolodine method. There was 77% agreement of results between the 2 test methods. Gastrointestinal transit time decreased with increasing volumes of blood. Occult blood testing was found to be useful for detection of blood in feces at volumes 20 to 50 times less than that required to cause melena.