Both L- and D-lactate contribute to metabolic acidosis in diarrheic calves

Effect of time of sample collection after onset of diarrhea on fecal microbiota composition of calves

BACKGROUND

The effect of time of sample collection after onset of diarrhea on the fecal microbiota composition of calves is unknown.

OBJECTIVE

Compare the fecal microbiota of calves with diarrhea onset on the day of sampling (D <24h), and calves having had diarrhea for >24 to 48 hours (D 24-48h).

ANIMALS

Thirty-one diarrheic calves (20 D <24h and 11 D 24-48h), 3 to 7 days of age.

METHODS

Cross-sectional study. Diarrhea was defined as a calf with loose feces or watery feces. Assessment of the fecal microbiota was performed by sequencing of 16S ribosomal RNA gene amplicons.

RESULTS

Richness and diversity were not statistically different between D <24h and D 24-48h (P > .05), but bacterial membership and structure differed significantly (AMOVA, P < .001 for both comparisons). Linear discriminant analysis effect size (LefSe) showed an enrichment of Faecalibacterium, Phocaeicola, Lachnospiracea, and Lactobacillus in the feces of D <24h calves, whereas Escherichia/Shigella, Ligilactobacillus, Clostridium_Sensu_Stricto, Clostridium_Incerta_Sedis, and Enterococcus were enriched in the D 24-48h calves.

CONCLUSION AND CLINICAL IMPORTANCE

Rapid changes in fecal microbiota occur during the first 48 hours of diarrhea with an enrichment of lactic acid-producing bacteria in D <24h followed by an enrichment in Escherichia/Shigella and Clostridium spp. in D 24-48h. The time from diarrhea onset to sampling appears to affect the bacterial composition. Researchers should standardize times for fecal collection based on the time of diarrhea.

Calf Diarrhea Is Associated With a Shift From Obligated to Facultative Anaerobes and Expansion of Lactate-Producing Bacteria

Diarrhea is the leading cause of morbidity, mortality and antimicrobial drug use in calves during the first month of age. Alteration in the bacterial communities of the gastrointestinal tract occurs during diarrhea. Diarrheic calves often develop anion gap (AG) acidosis associated with increased concentrations of unmeasured anions including D- and L-lactate. However, studies investigating the association between gut microbiota alterations and the development of acid-base disorders in diarrheic calves are lacking. We investigated the fecal bacterial alterations of calves with diarrhea and its association with changes in blood pH, and AG. Blood and fecal samples from healthy and diarrheic veal calves were taken 7 days after arrival to the farm. The fecal microbiota of healthy and diarrheic calves was assessed by sequencing of 16S ribosomal RNA gene amplicons. Blood gas analysis was completed using an i-Stat analyzer. In healthy calves, higher richness, evenness, and diversity were observed compared to diarrheic calves. Phocaeicola, Bacteroides, Prevotella, Faecalibacterium, Butyricicoccus, Ruminococcaceae and Lachnospiraceae were enriched in healthy compared with diarrheic calves. Enterococcus, Ligilactobacillus, Lactobacilus, Gallibacterium Streptococcus, and Escherichia/Shigella were enriched in diarrheic calves. In diarrheic calves, an increased abundance of lactate-producing bacteria including Lactobacillus, Streptococcus, Veillonella, Ligilactobacillus and Olsenella was detected. Diarrheic calves had a lower pH and bicarbonate concentration and a higher AG concentration than healthy calves. Together, these results indicate that calf diarrhea is associated with a shift from obligated to facultative anaerobes and expansion of lactate-producing bacteria which are related to acidemia, low bicarbonate and increase AG. Our results highlight the importance of the gastrointestinal microbiota on the clinicopathological changes observed in diarrheic calves.

Effect of fish oil and canola oil supplementation on immunological parameters, feed intake, and growth of Holstein calves

Supplemental n-3 fatty acids (FA) may support better immune responses than n-6 and n-9 FA in dairy calves. The objective was to evaluate the effect of n-3 FA, supplemented as a fish oil product (FO) in the milk replacer (MR), in comparison to n-6 and n-9 FA, supplemented as canola oil (CO), on body weight (BW), daily gain, and immunological parameters of preweaning Holstein calves. The study was conducted from September to December 2019. Calves were randomly allocated to a control group (n = 15; BW = 36.2 ± 1.5 kg; mean ± SEM) supplemented daily with 30 mL of CO and to an experimental group (n = 15; BW = 36.3 ± 1.5 kg) supplemented with 60 g of a product containing 30 g of FO. Both treatments were added to the MR during the morning feeding. All calves were fed 4 L of MR at 12.5% solids at 0700 and 1600 h for wk 1, 6 L from wk 2 to 7, and 3 L once daily (0700 h) during wk 8 until weaning (56 d). Blood samples were collected at 7, 14, 21, 28, 35, 42, 49, and 56 d of age for serum haptoglobin, TNF-α, IL-1β, and protectin. Dry matter intake was recorded in all experimental calves daily. Seroneutralization titers to vaccination against viral diseases (infectious bovine rhinotracheitis, parainfluenza 3, bovine viral diarrhea, and bovine respiratory syncytial virus) were determined. Mixed models for repeated measures were developed to analyze variables over time. Seroneutralization titers were analyzed by the Kruskal-Wallis test. The other variables were compared by a generalized linear model. Serum FA profile at 35 d of age showed that FO supported higher concentrations of n-3 FA than CO. Final BW [65.2 vs. 62.0 kg, standard error of the mean (SEM) = 2.1 kg] and average daily gain (0.52 vs. 0.46 kg/d, SEM = 0.1 kg/d) tended to be higher for the FO than the CO group. An interaction of treatment × day for dry matter intake was observed, especially during weaning (2.17 kg vs. 1.94 kg, SEM = 0.158 kg, for FO and CO group, respectively). Blood lactate (mmol/L) was higher in the CO than in the FO group at d 7. Haptoglobin and IL-1β were higher for the CO group on d 14 than the FO group. The TNF- α concentrations for the FO group were reduced over time, whereas the concentrations in the CO group remained constant. Protectin was higher in the FO group on d 14, but was lower on d 28, 35, and 49. Seroneutralization antibody titers postvaccination for the PI₃ virus were higher for the FO than the CO group. In conclusion, calves supplemented with FO had lower concentrations of blood lactate, haptoglobin, IL-1β and TNF-α than calves supplemented with CO during the study period. The FO supplementation had a higher DMI than CO supplementation. Results of this trial should be interpreted with caution due to the lack of a negative control group as well as the lower birth weight and growth rate observed under heat stress conditions.

Supplement Based on Fermented Milk Permeate for Feeding Newborn Calves: Influence on Blood, Growth Performance, and Faecal Parameters, including Microbiota, Volatile Compounds, and Fatty and Organic Acid Profiles

Simple Summary

Gastrointestinal infections and diarrhoea are the main health issues in young calves. The application of microbial products containing probiotics and prebiotics may lead to better management of the gut microbiome and improved calf health. After fermentation with selected lactic acid bacterial strains, milk permeate (a dairy industry by-product) contains lactic acid bacteria and prebiotics, both of which possess viable antimicrobial properties. We hypothesised that fermented milk permeate could be a prospective feed supplement for newborn calves. A 14-day experiment was conducted in which a group of newborn calves were given a supplement of milk permeate fermented with Lactobacillus uvarum LUHS245. A significantly higher count of lactic acid bacteria, a lower total count of enterobacteria, a higher species variety, and greater concentrations of both propionic acid and dry matter were found in the faeces of the calves fed with fermented milk permeate compared with a control group. Most of the fatty acids and volatile compounds in the faeces differed significantly between the two groups. The results suggest that supplementing the calves’ feed with fermented milk permeate has a positive effect on certain health parameters but no influence on blood parameters and growth performance.

Abstract

The aim of this study was to assess the effect of a feed supplement, namely milk permeate (MP) fermented with Lactobacillus uvarum LUHS245, on the newborn calves’ growth performance and blood and faecal parameters, including microbiota and volatile compound and fatty acid profiles. Ten female Holstein calves in the control group (CON group) were fed with a standard milk replacer diet and colostrum only, from day 2 to 14 of life, while 10 calves of the treated group (MP group) were fed with the same diet supplemented with 50 mL of the fermented MP. After 14 days, there were no significant differences between the groups in blood parameters, growth performance, or faecal pH. There was a significantly higher percentage of live lactic acid bacteria (by 17.02%), a lower percentage of enterobacteria (by 10.38%), a higher overall number of probiotic bacteria, a 1.7-fold higher species variety, and a higher content of dry matter in the faeces of the MP group (p < 0.05). The fatty acid and volatile compound profiles differed significantly between the groups. The results suggest that supplementing calves’ feed with fermented milk permeate has a positive effect on certain health parameters but not on blood parameters or growth performance.

Monitoring the Transition Period in Dairy Cows through 1H NMR-Based Untargeted Metabolomics

The metabolic alterations associated with the increase in milk production make the transition period critical to the health of dairy cows, usually leading to a higher incidence of disease in periparturient animals. In this manuscript, we describe the use of NMR-based untargeted metabolomics to follow how these changes impact the serum metabolome in a group of 28 transition dairy cows with no initial clinical diseases. Principal component analysis (PCA) of serum 1H NMR data from four weeks before calving to 8 weeks after parturition allowed us to clearly identify four stages during the transition period. Pairwise comparisons using orthogonal partial least square discriminant analysis (OPLS-DA) and univariate data analysis led to the identification of 18 metabolites that varied significantly through these stages. Species such as acetate, betaine, and creatine are observed early after calving, while other markers of metabolic stress, including acetone, β-hydroxybutyrate (BHB), and choline, accumulate significantly at the height of milk production. Furthermore, marked variations in the levels of lactate, allantoin, alanine, and other amino acids reveal the activation of different gluconeogenic pathways following parturition. Concomitant with a return to homeostasis, a gradual normalization of the serum metabolome occurs 8 weeks after calving. Correlations of metabolite levels with dietary and metabolic adaptations based on animal parity could also be identified. Overall, these results show that NMR-based chemometric methods are ideally suited to monitor manifestations of metabolic diseases throughout the transition period and to assess the impact of nutritional management schemes on the metabolism of dairy cows.

Dependence of the apparent bicarbonate space on initial plasma bicarbonate concentration and carbon dioxide tension in neonatal calves with diarrhea, acidemia, and metabolic acidosis

BACKGROUND

Marked strong ion (metabolic) acidosis in neonatal diarrheic calves usually is corrected by IV administration of NaHCO₃ . The distribution space for IV-administered bicarbonate, called the apparent bicarbonate space (ABS), appears to depend on initial plasma bicarbonate concentration (cHCO₃ ) and varies considerably in calves.

OBJECTIVE

To determine whether ABS was associated with initial plasma cHCO₃ and other acid-base variables.

ANIMALS

Twenty-five neonatal diarrheic calves with acidemia and metabolic acidosis.

METHODS

Prospective observational study using a convenience sample. Calves received NaHCO₃ (10 mmol/kg) and glucose (1.4 mmol/kg) IV in a crystalloid solution at 25 mL/kg over 60 minutes. The ABS (L/kg) was calculated at 4 time points over 2 hours after the end of the infusion. The relationship between ABS and initial acid-base variables was characterized using nonlinear, linear, and stepwise regression.

RESULTS

The median value for ABS calculated from the initial plasma cHCO₃ increased from 0.53 L/kg (range, 0.40-0.79) at the end of IV infusion to 0.96 L/kg (range, 0.54-1.23) 120 minutes later. Data obtained at the end of infusion provided the best fit to initial plasma cHCO₃ and jugular venous blood Pco₂ , such that: ABS = 0.41 + 1.06/cHCO₃ and ABS = 0.87-0.0082 × Pco₂ .

CONCLUSIONS AND CLINICAL IMPORTANCE

The observed median value for ABS of 0.53 L/kg in our study was similar to the empirically used value of 0.6. However, ABS values varied widely and were increased in calves with severe metabolic acidosis. We therefore recommend calculating ABS using the initial plasma cHCO₃ or venous blood Pco₂ , if respective measurements are available.

Changes in fluid and acid-base status of diarrheic calves on different oral rehydration regimens

The administration of oral rehydration solutions (ORS) is an effective method to treat dehydration and acidosis in calves suffering from diarrhea. The ORS can be prepared in water or milk. The aim of the present study was to elucidate how fluid and acid-base balance change after feeding milk compared with ORS prepared in water or milk to diarrheic calves. Calves (n = 30) with naturally acquired diarrhea were sequentially assigned in a 2:1 ratio to the following pretreatments: milk and water-ORS (pretreatment 1; n = 20 calves) or milk-ORS (pretreatment 2; n = 10 calves), respectively. The assignment was done on the day of diarrhea diagnosis. On d 3 ± 1 following assignment to pretreatment group, and after a fasting period of 9 h, diarrheic calves were subjected to the following treatments: 2 L of milk (pretreatment 1; n = 10 calves), water-ORS (pretreatment 1; n = 10 calves), or milk-ORS (pretreatment 2; n = 10 calves). Blood samples were taken before and at several time points until 6 h after feeding. Plasma protein, osmolality, and electrolytes were determined and a blood gas analysis was performed. Change in plasma volume was calculated according to plasma protein, and water intake during the experimental period was recorded. Plasma volume was increased 30 min after feeding water-ORS or milk but the increase was less pronounced after feeding milk compared with water-ORS. After feeding milk-ORS, no significant increase in plasma volume could be detected. Because of the pretreatment, plasma osmolality was higher in calves fed milk-ORS, but no change in plasma osmolality after feeding was detected. No difference in water consumption between the treatment groups was noted within the observed 6-h period. The pH was increased after feeding milk-ORS, whereas water-ORS and milk-feeding did not increase pH in blood. Pretreatment with milk-ORS resulted in higher baseline d-lactate concentration, but feeding milk-ORS reduced d-lactate values after feeding. In calves with diarrhea, plasma volume increased more quickly and to a greater extent after feeding water-ORS; thus, we recommend treating diarrheic calves with water-ORS before supplying milk. Nevertheless, diarrheic calves need milk to fulfill their energy needs. The administration of ORS in milk combined with free water access is more advisable than feeding milk exclusively because milk has no alkalinizing ability and contains less sodium. However, the effects of milk-ORS feeding on d-lactate levels in diarrheic calves need further elucidation.

Relationship between the values of blood parameters and physical status in Korean native calves with diarrhea

Dehydration, electrolyte disturbance, and acid-base imbalance are the most significant consequences of diarrhea in calves. We aimed to determine blood gas, hematological, electrolyte, and biochemical values and investigate the relationship between the physical status and blood parameters in Korean native calves (KNCs) with diarrhea. One hundred eighty KNCs with diarrhea (age < 75 days) were investigated. Blood samples were collected from the external jugular vein and analyzed using a portable clinical blood gas analyzer. The measured parameters were statistically compared according to the status of physical activity, dehydration, or prognosis. The mean values of parameters in the Calves with diarrhea showed metabolic acidosis, hyponatremia, and azotemia. The mean values of potassium, chloride, hematocrit, and hemoglobin were in the upper limit of their reference ranges. More than 75% of the calves had metabolic acidosis caused by bicarbonate loss, and 63.6% had high blood urea nitrogen (BUN) values. Moreover, BUN showed the highest correlation with the physical activity status and dehydration. pH, base excess of the extracellular fluid (BE), anion gap, potassium, hematocrit, bicarbonate, and hemoglobin were closely correlated with physical deterioration and dehydration (p < 0.001). BUN, pH, BE, and anion gap were closely correlated with physical deterioration and dehydration. These correlations between clinical symptoms and blood gas parameters can be clinically relevant in predicting the status of parameters according to clinical symptoms.

Vitreous humor endogenous compounds analysis for post-mortem forensic investigation

The chemical and biochemical analysis of bodily fluids after death is an important thanatochemical approach to assess the cause and time since death. Vitreous humor (VH) has been used as a biofluid for forensic purposes since the 1960s. Due to its established relevance in toxicology, a literature review highlighting the use of VH with an emphasis on endogenous compounds has not yet been undertaken. VH is a chemically complex aqueous solution of carbohydrates, proteins, electrolytes and other small molecules present in living organisms; this biofluid is useful tool for its isolated environment, preserved from bacterial contamination, decomposition, autolysis, and metabolic reactions. The post-mortem analysis of VH provides an important tool for the estimation of the post-mortem interval (PMI), which can be helpful in determining the cause of death. Consequently, the present review evaluates the recent chemical and biochemical advances with particular importance on the endogenous compounds present at the time of death and their modification over time, which are valuable for the PMI prediction and to identify the cause of death.

Serum D-lactate concentrations in dogs with parvoviral enteritis

BACKGROUND

Dogs infected with canine parvovirus (CPV) have compromised intestinal epithelial barrier integrity. Production of D-lactate by enteric bacteria may directly reflect disease severity or contribute to metabolic acid-base status in these dogs.

HYPOTHESIS

Serum D-lactate concentration will be increased in CPV dogs compared to healthy controls and correlate with markers of disease severity and acid-base status.

ANIMALS

Dogs with CPV undergoing treatment (n = 40) and healthy control dogs (n = 9).

METHODS

Prospective observational study. Dogs with CPV had a baseline and daily CBC, venous blood gas with serum electrolyte concentrations, composite clinical severity score, and serum D-lactate concentration performed. A single serum D-lactate measurement was obtained from healthy control dogs.

RESULTS

The CPV dogs had a higher D-lactate concentration (mean ± SD) of 469 ± 173 μM compared to controls, 306 ± 45 μM (P < .001). There was no difference in baseline D-lactate concentrations for CPV survivors (474 ± 28 μM), versus nonsurvivors (424 ± 116 μM; P = .70). D-lactate concentration decreased over the first 4 days of treatment (-9.6 μM/d; P = .46). Dogs hospitalized for <4 days had lower baseline D-lactate concentrations compared to those hospitalized ≥4 days (400 ± 178 μM versus 520 ± 152 μM; P = .03). No sustained correlation over time between serum D-lactate concentration and clinical severity score or recorded acid-base results.

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum D-lactate concentrations are higher in dogs with CPV compared to healthy controls but do not appear to be clinically relevant. No relationship identified between serum D-lactate concentrations and markers of CPV disease severity, acid-base status, or outcome.

Detection of endotoxin in plasma of hospitalized diarrheic calves

OBJECTIVES

To investigate whether lipopolysaccharide (LPS) is present in plasma of calves with naturally occurring diarrhea. The second objective was to determine whether plasma [LPS] correlates with clinical, hematological, biochemical, and acid-base variables, and whether [LPS] differs between surviving and nonsurviving diarrheic calves.

DESIGN

Prospective observational study (January 2012-May 2014).

SETTING

Veterinary teaching hospital.

ANIMALS

Thirty-four calves <28 days old admitted for diagnosis and treatment of diarrhea and 30 healthy control calves.

MEASUREMENTS AND MAIN RESULTS

Admission demographics, physical examination, blood gas, biochemistry analysis, and outcome data were recorded. Plasma concentration of LPS was determined using a bovine LPS ELISA assay. Plasma [LPS] was detected in both healthy and diarrheic calves. Plasma [LPS] was significantly higher in diarrheic than healthy calves (median: 0.99 ng/mL; Interquartile range (IQR): 0.068, vs 0.88 ng/mL; 0.065 ng/mL, respectively; P < 0.001). Plasma [LPS] was higher in nonsurviving (1.04 ng/mL; 0.07 ng/mL) than in surviving calves (0.98 ng/mL; 0.022 ng/mL; P < 0.001). Plasma [LPS] was higher in beef (1.07 ng/mL; 0.182 ng/mL) than in dairy diarrheic calves (0.99 ng/mL; 0.022 ng/mL; P < 0.001). In diarrheic calves, plasma [LPS] correlated with [l-lactate] (r² = 0.496; P = 0.002); hypoglycemia (r² = -0.453; P = 0.007); increased unmeasured strong ions (r² = 0.332; P = 0.050), [Mg²⁺ ] (r² = 0.475; P = 0.004), and [phosphate] (r² = 0.468; P = 0.005), and increased aspartate aminotransferase activity (r² = 0.348; P = 0.003).

CONCLUSIONS

This study highlights a potential role of LPS in the pathogenesis of metabolic derangements such as hyperlactatemia, hypoglycemia, and increased concentration of unmeasured strong anions in diarrheic calves. Further investigation evaluating the effect of LPS on l-lactate and glucose metabolism in diarrheic calves is warranted.

Effect of dehydration and acidemia on the potassium content of muscle tissue and erythrocytes in calves with neonatal diarrhea

Disturbances of extracellular potassium (K) homeostasis in calves with severe neonatal diarrhea have been studied extensively. Although total body depletion of this predominantly intracellular electrolyte is generally thought to occur in diarrheic calves, the mechanisms through which K depletion occurs are poorly understood. The aim of this study was to investigate how intracellular K homeostasis is affected by dehydration and acidemia, the 2 most important metabolic disturbances in calves with naturally occurring diarrhea. Twenty-seven calves with naturally occurring neonatal diarrhea, pronounced dehydration, and acidemia, and 2 groups of 10 healthy control calves were included in this study. Blood samples and muscle biopsies were obtained immediately before initiation of treatment (T₀) and after complete rehydration and correction of acidemia (T₁) from diarrheic calves. Blood samples were used to perform blood gas, blood biochemical, and hematological analyses and to determine K content in erythrocytes. Muscle biopsies were used to determine muscle tissue K content and tissue dry matter. Controls were used to determine values for erythrocyte and muscle tissue K content in healthy neonatal calves for comparison with diarrheic calves. As defined by the inclusion criteria, diarrheic calves showed pronounced acidemia and dehydration at T₀. Mean muscle tissue K content and tissue dry matter remained unchanged between sampling times and did not differ from values measured in healthy control calves. Erythrocyte K content increased from 73.63 ± 13.73 to 77.64 ± 15.97 mmol/L (±standard deviation) but was associated with a concomitant decline in erythrocyte volume. Values measured at both sampling times in diarrheic calves did not differ from erythrocyte K measured in healthy control calves. The plasma K concentration (median [interquartile range]) decreased from 5.44 [4.76-6.17] to 4.16 [3.99-4.31] mmol/L between T₀ and T₁. Although changes in plasma [K] were associated with the degree of dehydration, neither dehydration nor acidemia was associated with changes of K content in muscle tissue or erythrocytes. In conclusion, severe dehydration and acidemia in diarrheic calves were not associated with notable changes in K content of muscle tissue or erythrocytes. These results do not support the concept of pronounced K depletion occurring in calves with neonatal diarrhea. Erythrocytes are a poor surrogate tissue in which to measure changes of intracellular K content in diarrheic calves because of concomitant changes in erythrocyte volume that complicate the interpretation of results.

Impact of bacterial translocation in calves with atresia coli

OBJECTIVE

To identify whether enteric bacteria pass into the mesenteric lymph nodes (MLNs) and peritoneal cavity in calves with atresia coli and to evaluate whether the presence of bacterial translocation (BT) has an impact on the success of surgical treatment.

DESIGN

Prospective clinical study.

ANIMALS

Twenty-six client-owned calves.

INTERVENTIONS

During laparotomy, swab samples were collected from the peritoneal cavity and MLNs using a sterile swab stick and were submitted for microbiological analysis.

MEASUREMENTS AND MAIN RESULTS

Bacterial cultures of swab samples revealed that 65% (n = 17) of the calves experienced BT. Of these, 14 calves experienced BT to the MLNs, 9 to the peritoneal cavity, and 5 to both regions. Of the bacteria isolated from the MLNs, 72% (n = 10) were Escherichia coli. Of the samples isolated from the peritoneal fluid, 33% (n = 3) contained E. coli and 33% (n = 3) contained E. coli + coagulase-negative Staphylococcus (CNS). In calves with BT that were discharged (n = 13) and without BT that were discharged (n = 7), the median survival was 30 days; these data were found to be similar in the 2 groups.

CONCLUSIONS

This study revealed that BT is observed in the majority of atresia coli cases. E. coli is more common in BT, and translocation occurs primarily through the lymphatic route. These results suggest that the presence of BT is closely related to the success of the operation for correction of atresia coli.

Association of unmeasured strong ions with outcome of hospitalized beef and dairy diarrheic calves

Increased systemic concentrations of L-lactate and unmeasured strong ions (USI) are associated with an increased risk of mortality in human neonates and adults suffering from various diseases. This exploratory study aimed to investigate if values of certain acid-base parameters, especially L-lactate and USI, on admission to hospital are associated with mortality in diarrheic calves. Fifty-five calves < 28 days old admitted to 2 teaching hospitals for diagnosis and treatment of diarrhea were included. Admission demographic, physical examination, blood gas and biochemistry analysis, and outcome data were recorded. Admission acid-base values associated with outcome were assessed using multivariable regression modeling. Calves with elevated plasma L-lactate (OR: 1.30, 95% CI: 1.08 to 1.55; P = 0.005) and USI (OR: 1.40, 95% CI: 1.12 to 1.74; P = 0.003) at admission were more likely to die or to be euthanized. This study revealed that elevated concentrations of L-lactate and USI at admission were positively associated with mortality.

Influence of ad Libitum Feeding of Piglets With Bacillus Subtilis Fermented Liquid Feed on Gut Flora, Luminal Contents and Health

Some scholars caution that long-term ad libitum feeding with probiotic fermented food poses potential health risks to baby animals. We conducted a feeding experiment to investigate the influence of ad libitum feeding of pre-and post-weaned piglets with a Bacillus subtilis fermented diet on the gut microbiome, gut metabolomic profiles, bile acid metabolism, proinflammatory cytokines and faecal consistency. Compared with piglets fed a Bacillus subtilis-supplemented pellet diet, piglets fed the Bacillus subtilis fermented liquid diet had lower intestinal bacterial diversity (P > 0.05), higher intestinal fungal diversity (P > 0.05), more Firmicutes (P > 0.05), fewer Bacteroidetes, Actinobacteria and Proteobacteria (P > 0.05), higher concentrations of 3-hydroxypropionic acid (P < 0.05), orotic acid (P < 0.05), interleukin-6 (P < 0.01), lactic acid (P < 0.01), deoxycholic acid (P > 0.05) and lithocholic acid (P < 0.01) and a higher incidence of diarrhoea (P > 0.05). The data show that ad libitum feeding of piglets with a Bacillus subtilis fermented liquid diet during the suckling and early post-weaning periods promotes the growth of lactic acid bacteria, bile salt hydrolase-active bacteria and 7a-dehydroxylase-active bacteria in the intestinal lumen; disturbs the normal production of lactic acid, orotic acid and unconjugated bile acids; and increases circulating interleukin-6 levels and diarrhoea incidence.

Quantitative physicochemical analysis of acid-base balance and clinical utility of anion gap and strong ion gap in 806 neonatal calves with diarrhea

BACKGROUND

Acid-base abnormalities in neonatal diarrheic calves can be assessed by using the Henderson-Hasselbalch equation or the simplified strong ion approach which use the anion gap (AG) or the strong ion gap (SIG) to quantify the concentration of unmeasured strong anions such as D-lactate.

HYPOTHESIS/OBJECTIVES

To determine and compare the clinical utility of AG and SIG in quantifying the unmeasured strong anion charge in neonatal diarrheic calves, and to examine the associations between biochemical findings and acid-base variables by using the simplified strong ion approach. We hypothesized that the SIG provides a more accurate prediction of unmeasured strong anions than the AG.

ANIMALS

Eight hundred and six neonatal diarrheic calves admitted to a veterinary teaching hospital.

METHODS

Retrospective study utilizing clinicopathologic findings extracted from medical records.

RESULTS

Hyperphosphatemia was an important predictor of venous blood pH. Serum inorganic phosphorus and plasma D-lactate concentrations accounted for 58% of the variation in venous blood pH and 77% of the variation in AG and SIG. Plasma D- and total lactate concentrations were slightly better correlated with SIG (rs = -0.69; -0.78) than to AG (rs = 0.63; 0.74).

CONCLUSIONS AND CLINICAL IMPORTANCE

Strong ion gap is slightly better at quantifying the unmeasured strong anion concentration in neonatal diarrheic calves than AG. Phosphorus concentrations should be included as part of the calculation of Atot when applying the simplified strong ion approach to acid-base balance to critically ill animals with hyperphosphatemia.

Metabolic Profiling of Green Tea Treatments in Zucker Diabetic Rats Using 1H NMR

This study has investigated the metabolic effects of catechin-rich green tea (GT) and its formulation with ascorbic acid (AA) on the Zucker rat model of type 2 diabetes. AA is used to protect the GT catechins during digestion and increase bioavailability. Thirty two Zucker diabetic fatty (ZDF) rats were randomly divided into four groups (n=8 in each group) and treated with water, GT, AA and GT+AA respectively for five weeks. Urinary metabolic profiles were determined using ¹H NMR spectroscopy. Fourteen metabolites were identified and their 24-hr excretions were quantified. Changes in the 14 metabolites demonstrated differential treatment effects on the metabolism of ZDF rats. GT and AA were found to be able to independently reduce urinary excretions of most metabolites that were over-excreted in the control diabetic rats, such as oxidative stress marker metabolites and TCA cycle metabolites. GT showed a great potential in controlling metabolic acidosis by suppressing the excretion of lactic acid and acetic acid from diabetic rats and GT+AA showed a remarkably stronger suppression than GT while AA was unable to suppress these two acids. Further investigation is needed to better understand the role of GT and/or formulated GT in altering the metabolic pathways in the diabetic animal model as well as in humans.

Evaluation of 4 point-of-care units for the determination of blood l-lactate concentration in cattle

BACKGROUND

Despite being used commonly in bovine medicine, information on reliability of point-of-care (POC) lactate meters is limited.

OBJECTIVE

To determine the validity of 4 commercially available POC lactate meters in cattle.

ANIMALS

Cattle with various diseases (n = 120).

METHODS

Blood samples collected from the jugular vein were processed immediately on POC lactate meters. Plasma l-lactate concentration was measured by the enzymatic-colorimetric method (ELISA). Data were subjected to Friedman's test for comparison, Passing-Bablok regression and Bland-Altman plot analyses for reliability, and receiver operating characteristics analysis for sensitivity (Se) and specificity (Sp).

RESULTS

The POC lactate meters were highly correlated with ELISA (r = 0.98-0.99) despite disagreements among units. When regressed on ELISA, blood l-lactate concentrations generated from Accutrend Plus and Lactate Pro were linear up to 16.6 and 15.7 mmol/L, respectively, whereas those generated from i-STAT and Lactate Scout were linear up to 19.5 and 19.7 mmol/L, respectively. All POC lactate meters had a Se of 100% with Sp of 95.7-98.6% at a plasma l-lactate cut-off concentration of 4 mmol/L. i-STAT had the best accuracy (99.0%) and precision (99.8%), the best linear fit (y = -0.13 + 1.04X) yielding the lowest bias (-6.6%) as well as the highest Se (100%) and Sp (98.6%).

CONCLUSIONS AND CLINICAL IMPORTANCE

Despite high correlation with the reference method, dilution is needed for Accutrend Plus/Lactate Pro and i-STAT/Lactate Scout if concentrations >15 and 20 mmol/L, respectively. i-STAT provided the most accurate and precise results.

Contribution of unmeasured anions to acid-base disorders and its association with altered demeanor in 264 calves with neonatal diarrhea

Background

The quantitative effect of strong electrolytes, unmeasured anions (UAs), pCO₂, and plasma protein concentrations in determining plasma pH and bicarbonate (HCO₃⁻) can be demonstrated using the physicochemical approach. Demeanor of calves with diarrhea is associated with acidemia, dehydration, and hyper‐d‐lactatemia.

Hypothesis

Unmeasured anions are a major factor influencing changes in plasma pH and HCO₃⁻ of calves with diarrhea and UAs and strong UAs, estimated by anion gap (AG) and strong ion gap (SIG), respectively, are more strongly associated with alteration of demeanor compared to other acid–base variables.

Animals

A total of 264 calves with diarrhea from two data sets (DS1 and DS2).

Methods

Retrospective study. Forward stepwise regression was performed to determine the relationship between measured pH or HCO₃⁻, and physicochemical variables. A two‐way ANOVA was performed to investigate the association between acid–base variables and attitude (bright, obtunded, and stuporous), posture (standing, sternal or lateral recumbency), and strength of suckling reflex (strong, weak, or absent).

Results

Increased strong UAs estimated by SIG was the most important contributor to changes in measured pH and HCO₃⁻ (DS1: r² 66 and 59%, DS2: 39 and 42%, P < .0001). SIG and AG were correlated to deteriorating calf demeanor for all three clinical scoring categories: attitude, posture, and suckle reflex (P < .0001).

Conclusion and Clinical Relevance

Elevated concentrations of strong UAs were the primary cause of acidemia and had an important influence on the demeanor of calves with diarrhea. These findings emphasize the importance of the calculation of UAs when evaluating acid–base abnormalities in calves.

Clinical, microbiological and histological findings in lambs affected by 'salivary abomasum disease'

'Salivary abomasum disease' is a common syndrome in Greece affecting lambs and kids from three to 17 days of age. In this case series, we present clinical and laboratory findings from 37 affected lambs presented alive and subsequently euthanased for welfare reasons and necropsied, and also from 24 other lambs submitted dead that were also necropsied. The clinical signs in the 37 lambs presented alive included lethargy (100 per cent), absence of sucking (83.8 per cent), weakness (37.8 per cent), abdominal distension (40.5 per cent) and increased frequency of urination (24.3 per cent). Diarrhoea was not observed in any affected lambs. At necropsy of these 37 lambs, the abomasum was distended with gas (70.3 per cent), saliva (43.2 per cent) along with mixed milk clots and gastric secretions; while multiple small mucosal and serosal haemorrhages with blood clots ('coffee grains') were recorded (91.9 per cent). Eight of 37 lambs that were examined alive, had elevated blood urea nitrogen concentrations (21.6 per cent). The pH of the abomasal contents ranged from 1.0 to 2.8; Escherichia coli was cultured from six of 37 (16.2 per cent) abomasal fluid samples. A mild to moderate inflammatory cell infiltrate was present in the mucosal lamina propria of 13 of 15 abomasal samples (86.6 per cent). Kidneys were paler than normal in 13 of the total 61 lambs necropsied (21.3 per cent); while acute tubular necrosis was evident on histopathological examination of 11 of 12 examined pale kidneys (91.6 per cent). The low abomasal pH and reported successful treatment with oral sodium bicarbonate suggest that metabolic acidosis may develop during the disease; however, further studies, including blood gas analysis, and determination of D- and L-lactic acid concentrations, are necessary to confirm this hypothesis.

Construction and validation of a decision tree for treating metabolic acidosis in calves with neonatal diarrhea

BACKGROUND

The aim of the present prospective study was to investigate whether a decision tree based on basic clinical signs could be used to determine the treatment of metabolic acidosis in calves successfully without expensive laboratory equipment. A total of 121 calves with a diagnosis of neonatal diarrhea admitted to a veterinary teaching hospital were included in the study. The dosages of sodium bicarbonate administered followed simple guidelines based on the results of a previous retrospective analysis. Calves that were neither dehydrated nor assumed to be acidemic received an oral electrolyte solution. In cases in which intravenous correction of acidosis and/or dehydration was deemed necessary, the provided amount of sodium bicarbonate ranged from 250 to 750 mmol (depending on alterations in posture) and infusion volumes from 1 to 6.25 liters (depending on the degree of dehydration). Individual body weights of calves were disregarded. During the 24 hour study period the investigator was blinded to all laboratory findings.

RESULTS

After being lifted, many calves were able to stand despite base excess levels below -20 mmol/l. Especially in those calves, metabolic acidosis was undercorrected with the provided amount of 500 mmol sodium bicarbonate, which was intended for calves standing insecurely. In 13 calves metabolic acidosis was not treated successfully as defined by an expected treatment failure or a measured base excess value below -5 mmol/l. By contrast, 24 hours after the initiation of therapy, a metabolic alkalosis was present in 55 calves (base excess levels above +5 mmol/l). However, the clinical status was not affected significantly by the metabolic alkalosis.

CONCLUSIONS

Assuming re-evaluation of the calf after 24 hours, the tested decision tree can be recommended for the use in field practice with minor modifications. Calves that stand insecurely and are not able to correct their position if pushed require higher doses of sodium bicarbonate, if there is clinical evidence of a marked D-lactic acidosis. In those calves, determining the degree of loss of the palpebral reflex was identified as a useful decision criterion to provide an additional amount of 250 mmol sodium bicarbonate. This work demonstrates the clinical relevance of the discovery that D-lactate is responsible for most of the clinical signs expressed in neonatal diarrheic calves suffering from metabolic acidosis.

Serum D-lactate concentrations in cats with gastrointestinal disease

BACKGROUND

Increased D-lactate concentrations cause neurological signs in humans with gastrointestinal disease.

HYPOTHESIS/OBJECTIVES

To determine if serum D-lactate concentrations are increased in cats with gastrointestinal disease compared to healthy controls, and if concentrations correlate with specific neurological or gastrointestinal abnormalities.

ANIMALS

Systematically selected serum samples submitted to the Gastrointestinal Laboratory at Texas A&M University from 100 cats with clinical signs of gastrointestinal disease and abnormal gastrointestinal function tests, and 30 healthy cats.

METHODS

Case-control study in which serum D- and L-lactate concentrations and retrospective data on clinical signs were compared between 30 healthy cats and 100 cats with gastrointestinal disease. Association of D-lactate concentration with tests of GI dysfunction and neurological signs was evaluated by multivariate linear and logistic regression analyses, respectively.

RESULTS

All 100 cats had a history of abnormal gastrointestinal signs and abnormal gastrointestinal function test results. Thirty-one cats had definitive or subjective neurological abnormalities. D-lactate concentrations of cats with gastrointestinal disease (median 0.36, range 0.04-8.33 mmol/L) were significantly higher than those in healthy controls (median 0.22, range 0.04-0.87 mmol/L; P = .022). L-lactate concentrations were not significantly different between the 2 groups of cats with gastrointestinal disease and healthy controls. D-lactate concentrations were not significantly associated with fPLI, fTLI, cobalamin, folate, or neurological abnormalities (P > .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

D-lactate concentrations can be increased in cats with gastrointestinal disease. These findings warrant additional investigations into the role of intestinal microbiota derangements in cats with gastrointestinal disease, and the association of D-lactate and neurological abnormalities.

Importance of the effective strong ion difference of an intravenous solution in the treatment of diarrheic calves with naturally acquired acidemia and strong ion (metabolic) acidosis

BACKGROUND

The effect of sodium bicarbonate on acid-base balance in metabolic acidosis is interpreted differently by Henderson-Hasselbalch and strong ion acid-base approaches. Application of the traditional bicarbonate-centric approach indicates that bicarbonate administration corrects the metabolic acidosis by buffering hydrogen ions, whereas strong ion difference theory indicates that the co-administration of the strong cation sodium with a volatile buffer (bicarbonate) corrects the strong ion acidosis by increasing the strong ion difference (SID) in plasma.

OBJECTIVE

To investigate the relative importance of the effective SID of IV solutions in correcting acidemia in calves with diarrhea.

ANIMALS

Twenty-two Holstein-Friesian calves (4-21 days old) with naturally acquired diarrhea and strong ion (metabolic) acidosis.

METHODS

Calves were randomly assigned to IV treatment with a solution of sodium bicarbonate (1.4%) or sodium gluconate (3.26%). Fluids were administered over 4 hours and the effect on acid-base balance was determined.

RESULTS

Calves suffered from acidemia owing to moderate to strong ion acidosis arising from hyponatremia and hyper-D-lactatemia. Sodium bicarbonate infusion was effective in correcting the strong ion acidosis. In contrast, sodium gluconate infusion did not change blood pH, presumably because the strong anion gluconate was minimally metabolized.

CONCLUSIONS

A solution containing a high effective SID (sodium bicarbonate) is much more effective in alkalinizing diarrheic calves with strong ion acidosis than a solution with a low effective SID (sodium gluconate). Sodium gluconate is ineffective in correcting acidemia, which can be explained using traditional acid-base theory but requires a new parameter, effective SID, to be understood using the strong ion approach.

Metabolic acidosis in neonatal calf diarrhea-clinical findings and theoretical assessment of a simple treatment protocol

BACKGROUND

Clinical assessment of metabolic acidosis in calves with neonatal diarrhea can be difficult because increased blood concentrations of d-lactate and not acidemia per se are responsible for most of the clinical signs exhibited by these animals.

OBJECTIVES

To describe the correlation between clinical and laboratory findings and d-lactate concentrations. Furthermore, the theoretical outcome of a simplified treatment protocol based on posture/ability to stand and degree of dehydration was evaluated.

ANIMALS

A total of 121 calves with diagnosis of neonatal diarrhea admitted to a veterinary teaching hospital during an 8-month study period.

METHODS

Prospective blinded cohort study. Physical examinations were carried out following a standardized protocol. Theoretical outcome of treatment was calculated.

RESULTS

Type and degree of metabolic acidosis were age dependent. The clinical parameters posture, behavior, and palpebral reflex were closely correlated to base excess (r = 0.74, 0.78, 0.68; P < .001) and d-lactate concentrations (r = 0.59, 0.59, 0.71; P < .001), respectively. Thus, determining the degree of loss of the palpebral reflex was identified as the best clinical tool for diagnosing increase in serum d-lactate concentrations. Theoretical outcome of treatment revealed that the tested dosages of sodium bicarbonate are more likely to overdose than to underdose calves with diarrhea and metabolic acidosis.

CONCLUSIONS AND CLINICAL IMPORTANCE

The degree of metabolic acidosis in diarrheic calves can be predicted based on clinical findings. The assessed protocol provides a useful tool to determine bicarbonate requirements, but a revision is necessary for calves with ability to stand and marked metabolic acidosis.

Peritoneal and plasma D-lactate concentrations in horses with colic

OBJECTIVE

To evaluate the association between peritoneal fluid and plasma d-lactate concentration with variables used in the diagnosis and prognosis of horses with colic.

ANIMALS

Clinically healthy horses (n=6) and 90 horses with colic.

STUDY DESIGN

Prospective cross-sectional study.

METHODS

D-lactate concentration was determined in peritoneal fluid and plasma of all horses. Information on other blood and peritoneal fluid variables, signalment, results from the physical examination, outcome, need for surgery, lesion location, and type was retrieved from medical records.

RESULTS

Peritoneal D-lactate concentration was strongly correlated with plasma D-lactate concentration (r=0.71; P<.001). Peritoneal and plasma D-lactate concentrations were positively correlated with peritoneal (r=0.8; P<.001) and plasma L-lactate (r=0.33; P=.001) concentrations, respectively. Peritoneal D-lactate concentration was negatively correlated with survival to discharge (U=430.5; P<.001). Median peritoneal D-lactate concentration of horses with septic peritonitis (455.2 μmol/L) and horses with gastrointestinal rupture (599.5 μmol/L) were higher compared with horses with nonstrangulating obstructions (77.7 μmol/L). A cut-off concentration of peritoneal D-lactate of 116.6 μmol/L had a sensitivity of 0.813 and a specificity of 0.651 to differentiate between nonstrangulating and strangulating obstructions.

CONCLUSIONS

Peritoneal D-lactate concentration may be more useful for identifying horses with strangulating obstructions (high sensitivity, low probability of a false negative) than to ruling out strangulating obstruction (moderate specificity, high probability of a false positive).

Comparison of the effects of intravenous administration of isotonic and hypertonic sodium bicarbonate solutions on venous acid-base status in dehydrated calves with strong ion acidosis

OBJECTIVE-To compare the effects of IV administration of isotonic (1.3%) and hypertonic (8.4%) sodium bicarbonate (NaHCO(3)) solutions on acid-base status in dehydrated calves with strong ion (metabolic) acidosis. DESIGN-Randomized controlled clinical trial. ANIMALS-50 calves with diarrhea and severe dehydration. PROCEDURES-Calves were randomly assigned to receive isotonic NaHCO(3) solution (65 mL/kg [29.5 mL/lb], IV) over 3 hours (n = 30) or hypertonic NaHCO(3) solution (10 mL/kg [4.5 mL/lb], IV) over 20 minutes (20). Blood samples were collected at 0 hours (immediately prior to solution administration) and at 0.5, 1, 2, and 4 hours after administration began. Samples were submitted for blood gas analysis, serum biochemical analysis, and determination of blood Na(+), K(+), and Cl(-) concentrations and percentage change in plasma volume. RESULTS-Calves that received isotonic NaHCO(3) solution had an increase in venous blood pH, HCO(3) concentration, and base excess; a small, transient increase in Po(2); and no change in Pco(2) within 4 hours after administration began. Calves that received hypertonic NaHCO(3) solution had an immediate increase in venous blood pH, HCO(3) concentration, and base excess; a small, transient increase Pco(2); and no change in Po(2) within 0.5 hours after treatment began. Plasma volume increased to a greater extent following administration of isotonic solution than after administration of hypertonic solution. CONCLUSIONS AND CLINICAL RELEVANCE-IV administration of 8.4% NaHCO(3) solution in small volumes provided fast and effective improvement of severe acid-base abnormalities in calves with severe strong ion acidosis but did not improve hydration status as well as administration of a larger volume of isotonic NaHCO(3) solution.

Treatment of calf diarrhea: oral fluid therapy

Diarrhea remains the leading cause of mortality in beef and dairy calves. Calves that have diarrhea frequently develop dehydration, strong ion acidosis, and electrolyte abnormalities, and are in a state of negative energy balance. Oral electrolyte therapy is a simple and economical method of addressing all of these potential complications. This article gives an overview of oral electrolyte therapy of calves, including indications, guidelines for administration, and how to choose an electrolyte product.

Treatment of calf diarrhea: intravenous fluid therapy

Severely dehydrated calves that are unable to suckle need intravenous fluids for effective resuscitation. Intravenous fluid therapy is also indicated for sick calves without obvious dehydration, such as calves with strong ion acidosis, ruminal acidosis (rumen drinkers), severe pneumonia, septicemia, or hypothermia. This article presents an updated overview of intravenous fluid therapy for calves, recent insights into the development of metabolic acidosis in young calves resulting from accumulation of D-lactate, a simplified algorithm for intravenous fluid therapy, and a procedure for ear vein catheterization under field conditions.

Enumeration of some cultivable bacterial groups and characterization of some abiotic variables in the jejunoileal content of Prim'Holstein veal calves

A study was conducted to characterize the bacterial and biochemical composition of the jejunoileal content of veal calves and the effect of pre-slaughter fasting time. At 22 wk of age, 22 preruminant Prim'Holstein calves fed milk replacer and pellets (mainly composed of corn) were slaughtered at 6, 12, or 24 h after their last meal. Chyme samples were collected from the jejunoileal compartment just after slaughter, and pH and redox potential were immediately measured. Culture-based methods were used to determine the concentrations of total anaerobic microflora, lactate-utilizing bacteria, Bacteroides fragilis group, Lactobacilli, Bifidobacteria, Enterococci, and 2 potential pathogenic species, Escherichia coli and Clostridium perfringens. Concentrations of l-lactate, ammonia, and short-chain fatty acids (SCFA) were determined on frozen samples. The biochemical composition (DM, total protein, lactose, galactose, glucose, minerals, AA profile, and fatty acid profile) of the jejunoileal content was determined only on samples from the 6-h fasted group. Microflora concentrations were greater (P < 0.01) in the 6-h fasted group compared with the 12- and 24-h fasted groups, involving a decreased pH (P < 0.05) and greater lactate and SCFA concentrations, both linked directly to the fermentative state of the microorganisms. The 6-h fasted group showed the least interanimal variability in bacterial group levels, except for Cl. perfringens, which presented increased interanimal variability regardless of fasting time. At 6 h postprandial, the jejunoileal content of veal calves seemed to be in a stable state, allowing the creation of a database on its biochemical composition. This study is a key first step in the development of an in vitro system for modeling the jejunoileal ecosystem of veal calves. This model will provide a useful tool for assessing the effects of feed additives on intestinal microflora.

Clinical efficacy of intravenous hypertonic saline solution or hypertonic bicarbonate solution in the treatment of inappetent calves with neonatal diarrhea

Background: The clinical efficacy of IV administered hypertonic saline solution and hypertonic bicarbonate solution (HBS) in the treatment of inappetent diarrheic calves has not been compared yet.

Hypothesis: HBS is more advantageous than hypertonic saline in the treatment of calves with severe metabolic acidosis.

Animals: Twenty‐eight dehydrated, inappetent calves with neonatal diarrhea.

Methods: In 2 consecutive clinical studies, calves were initially treated with saline (5.85%; 5 mL/kg body weight [BW] over 4 minutes; study I: N = 16) or bicarbonate solution (8.4%; 10 mL/kg BW over 8 minutes; study II: N = 12), respectively, followed by oral administration of 3 L isotonic electrolyte solution 5 minutes after injection. Clinical and laboratory variables were monitored for 72 hours.

Results: Treatment failed in 6 calves of study I and in 1 calf of study II as indicated by a deterioration of the general condition. All treatment failures had more severe metabolic acidosis compared with successfully treated calves before treatment. In the latter, rehydration was completed within 18 hours after injection; metabolic acidosis was corrected within 24 hours (study I) and 6 hours (study II) after injection.

Conclusions and Clinical Importance: Diarrheic calves with slight metabolic acidosis (base excess [BE] >−10 mM) can be treated successfully with hypertonic saline. HBS is appropriate in calves without respiratory problems with more severe metabolic acidosis (BE up to −20 mM). Intensive care of the calves is required to ensure a sufficient oral fluid intake after the initial IV treatment.

Influence of experimental Eimeria zuernii infection in calves on electrolyte concentrations, acid–base balance and blood gases

Coccidiosis, often caused by Eimeria zuernii, is an important disease in calf rearing and is clinically mainly associated with diarrhoea (PR Fitzgerald in Adv Vet Sci Comp Med, 24:121-143, 1980). Calves were experimentally infected with E. zuernii oocysts to investigate the effects of artificial E. zuernii coccidiosis on electrolyte concentrations, acid-base balance and blood gases. Therefore, animals were assigned to three groups: group 1 (n = 14) served as uninfected control group, group 2 (n = 11) was infected with 150,000 sporulated E. zuernii oocysts per calf, and group 3 (n = 16) was infected with 250,000 sporulated E. zuernii oocysts per calf. Aberrances which were attributed to coccidiosis were observed in the following parameters: sodium and chloride concentrations, pH (only high-dose infected group 3), base excess, standard bicarbonate, total carbon dioxide and partial pressure of carbon dioxide. Alterations were most pronounced in the high-dose infected group 3. Anion gap and oxygen saturation did not show significant differences between the groups. Due to diarrhoea and malabsorption in coccidiosis-affected calves, there is a distinct loss not only of fluid and blood but also of electrolytes and alkaline buffer substances which provokes the development of an acidosis. This is counteracted by metabolism and respiration but cannot be compensated in severely affected and moribund calves.

D-Lactic acid-induced neurotoxicity in a calf model

Lactic acidosis (DAC) occurs as a complication of short-bowel syndrome in humans and in a variety of other gastrointestinal disorders in monogastrics and ruminants. DAC is associated with signs of impaired central nervous system (CNS) function including ataxia and coma. The objective of this experiment was to determine whether either acidification of nervous tissue or d-lactic acid is responsible for decreased neurological function. Eight Holstein calves (32 +/- 11 days, 70 +/- 10 kg) were surgically catheterized with indwelling intravenous jugular and atlanto-occipital space cerebrospinal fluid (CSF) catheters and infused for 6 h in random order with isomolar dl-lactic acid (dl-LA), l-lactic acid (l-LA), hydrochloric acid (HCl), or saline. dl-LA induced ataxia after 4 h of infusion and produced the greatest obtunding of CNS function (at 7 h, score 8.0 +/- 0.4), whereas the other infusions caused neither ataxia nor scores over 1.5 (P < 0.01 from dl-LA). dl-LA induced significantly less acidemia than HCl (at 6 h pH 7.13 +/- 0.06 and 7.00 +/- 0.04, base excess -16 +/- 1 and -23 +/- 3 mmol/l, bicarbonate 11 +/- 1 and 8 +/- 1 mmol/l respectively, all P < 0.01) but greater than l-LA and saline (P < 0.01). CSF changes followed a similar but less pronounced pattern. Although HCl infusion produced a severe acidemia and CSF acidosis, only minor effects on neurological function were evident suggesting that d-lactate has a direct neurotoxic effect that is independent of acidosis. Conversely, l-LA produced only minor neurological changes.

Investigations on the association of D-lactate blood concentrations with the outcome of therapy of acidosis, and with posture and demeanour in young calves with diarrhoea

The objective of this prospective study was to elucidate whether amounts of bicarbonate needed for correction of acidosis and normalization of clinical signs are influenced by blood D-lactate concentrations in calves with diarrhoea. In 73 calves up to 3 weeks old with acute diarrhoea and base excess values below -10 mmol/l correction of acidosis was carried out within 3.5-h by intravenous administration of an amount of sodium bicarbonate which was calculated using the formula: HCO (mmol) = body mass (kg) x base deficit (mmol/l) x 0.6 (l/kg). Clinical signs, venous base excess, and plasma D-lactate concentrations were monitored immediately following admission, following correction of acidosis at 4 h and 24 h after admission. The base excess and plasma D-lactate concentrations throughout the study were -17.8 +/- 4.0, -0.4 +/- 0.4, -3.0 +/- 5.5 mmol/l (base excess), and 10.0 +/- 4.9, 9.8 +/- 4.8, 5.4 +/- 3.4 mmol/l (D-lactate) for the three times of examination. Metabolic acidosis was not corrected in more than half of the calves (n = 43) by the calculated amount of bicarbonate, whereas the risk of failure to correct acidosis increases with D-lactate concentrations. The study shows that calves with elevated D-lactate concentrations do not need additional specific therapy, as D-lactate concentrations regularly fall following correction of acidosis and restitution of body fluid volume, for reasons that remain unclear. However, calves with distinct changes in posture and demeanour need higher doses of bicarbonate than calculated with the factor of 0.6 in the formula mentioned above probably because of D-hyperlactataemia.

Fecal D- and L- lactate, succinate, and volatile fatty acid levels in young dairy calves

For evaluation of physiologically significant organic anions in the colonic environment, 87 samples of normal feces were collected from the rectum of 15 calves less than 60 days old. The calves were fed milk replacer with free access to starter diet and hay. After fecal extraction with water, pH, D- and L-lactate, succinate, and volatile fatty acid (VFA) concentrations were determined. There was wide variation in fecal pH (4.3 to 7.7). Higher lactate concentrations were observed in feces samples with lower pH, and most of these samples were collected during the first 4 weeks of life. Elevated lactate concentrations included both the D- and L-isomers, and the D-isomer comprised approximately 30-50% of total lactate. Elevated succinate concentrations were observed in only 8 fecal samples, while other samples had lower or trace amounts of succinate. Elevated fecal succinate showed no relationship with fecal pH or VFA concentrations. Fecal VFA concentrations were lower in samples collected in the early postnatal stage, but fecal VFA concentrations were not necessarily related to age. We confirmed that fecal D- and L-lactate concentrations increased with a concomitant decrease of VFA in the acidic lumen of the colon, although acidic feces were not necessarily accompanied by elevated concentrations of lactate. In contrast, succinate production was not related to fecal pH or VFA concentrations.

Lactobacillus GG does not affect D-lactic acidosis in diarrheic calves, in a clinical setting

D-lactate, produced by gastrointestinal fermentation, is a major contributor to metabolic acidosis in diarrheic calves. Lactobacillus rhamnosus GG survives gastrointestinal transit in the neonatal calf and does not produce D-lactate. To determine whether this probiotic reduces gastrointestinal D-lactate production or severity of diarrhea or both, 48 calves (mean, 11 days old; range, 2-30 days) admitted to the clinic for treatment of diarrhea were randomly allocated to 2 groups. The experimental group was given Lactobacillus rhamnosus GG (1 x 10(11) cfu/d) PO, dissolved in milk or oral electrolyte solution, in addition to clinic treatment protocols; the other group served as a control. Serum and fecal samples were obtained at admission and at 24 and 48 hours after initial administration of Lactobacillus rhamnosus GG. All samples were analyzed for D- and L-lactate by using high-pressure liquid chromatography. Feces were also analyzed for pathogens, Lactobacillus rhamnosus GG recovery, and dry matter. D-lactic acidemia (>3 mmol/L) was present in 37/48 calves at admission. Lactobacillus rhamnosus GG was recovered in the feces of 13 experimental calves and 0 control calves 24 hours after administration. No difference in serum or fecal D- or L-lactate between the groups was detected at any time point. After therapy, D-lactic acidosis was absent at 48 hours in all but 1 calf. No relation between fecal pathogen (viral, bacterial, or protozoal) and degree of D-lactic acidosis was observed. The reduction in mortality and greater fecal dry matter in Lactobacillus rhamnosus GG-treated calves was not statistically significant.

Lactobacillus GG does not affect D-lactic acidosis in diarrheic calves, in a clinical setting

D‐lactate, produced by gastrointestinal fermentation, is a major contributor to metabolic acidosis in diarrheic calves. Lactobacillus rhamnosus GG survives gastrointestinal transit in the neonatal calf and does not produce D‐lactate. To determine whether this probiotic reduces gastrointestinal D‐lactate production or severity of diarrhea or both, 48 calves (mean, 11 days old; range, 2–30 days) admitted to the clinic for treatment of diarrhea were randomly allocated to 2 groups. The experimental group was given Lactobacillus rhamnosus GG (1×10¹¹ cfu/d) PO, dissolved in milk or oral electrolyte solution, in addition to clinic treatment protocols; the other group served as a control. Serum and fecal samples were obtained at admission and at 24 and 48 hours after initial administration of Lactobacillus rhamnosus GG. All samples were analyzed for D‐and L‐lactate by using high‐pressure liquid chromatography. Feces were also analyzed for pathogens, Lactobacillus rhamnosus GG recovery, and dry matter. D‐lactic acidemia (>3 mmol/L) was present in 37/48 calves at admission. Lactobacillus rhamnosus GG was recovered in the feces of 13 experimental calves and 0 control calves 24 hours after administration. No difference in serum or fecal D‐ or L‐lactate between the groups was detected at any time point. After therapy, D‐lactic acidosis was absent at 48 hours in all but 1 calf. No relation between fecal pathogen (viral, bacterial, or protozoal) and degree of D‐lactic acidosis was observed. The reduction in mortality and greater fecal dry matter in Lactobacillus rhamnosus GG‐treated calves was not statistically significant.

D-lactic acidosis

D-lactic acidosis, also referred to as D-lactate encephalopathy, is a rare neurologic syndrome that occurs in individuals with short bowel syndrome or following jejuno-ileal bypass surgery. Symptoms typically present after the ingestion of high-carbohydrate feedings. Neurologic symptoms include altered mental status, slurred speech, and ataxia, with patients often appearing drunk. Onset of neurologic symptoms is accompanied by metabolic acidosis and elevation of plasma D-lactate concentration. In these patients, malabsorbed carbohydrate is fermented by an abnormal bacterial flora in the colon, which produces excessive amounts of D-lactate. High amounts of D-lactate are absorbed into the circulation, resulting in an elevated concentration of D-lactate in the blood. Development of neurologic symptoms has been attributed to D-lactate, but it is unclear if this is the cause or whether other factors are responsible. This review examines the pathophysiology of the production and accumulation of D-lactate while exploring the potential factors contributing to the development of neurologic manifestations. Methods of diagnosis and treatment are reviewed. Areas requiring further investigation are identified.