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

A scoping review of neonatal calf diarrhea case definitions

Various case descriptions and scoring systems have been used to define neonatal calf diarrhea (NCD) and diverse diarrhea-related outcomes are reported, which limits direct comparison between studies. Therefore, the objective of this scoping review was to characterize the case definitions used for NCD and describe diarrhea-related outcomes to inform future efforts towards standardization. A literature search identified articles using 3 databases (Medline, CAB Direct, Agricola), along with Google and Google Scholar. This returned 16,854 unique articles, which were then screened for eligibility by two independent reviewers, resulting in 555 being selected for data extraction. Among articles, the study populations included mostly dairy-breed calves (88%; n = 486) while the remainder evaluated beef, crossbred, or dual purpose beef/dairy calves (10%; n = 53), or did not report breed (3%; n = 16). Studies used between 1 and 8 metrics to define NCD, with 933 unique metrics extracted in total. The most common metric was fecal consistency alone (30%; n = 281), or with at least 1 other metric (26%; n = 241). To define diarrhea, fecal consistency was either described qualitatively (e.g., "profuse liquid feces"), or semi-quantitatively, for example using a scoring system that frequently included 4 levels (n = 208). Some NCD case definitions included fecal color, volume, or odor (10%; n = 98), physical exam parameters (8%; n = 79), the duration of abnormal feces (7%; n = 67), the presence of abnormal contents (e.g., blood, 7%; n = 61), farm treatment records (6%; n = 54), fecal dry matter (1%; n = 12), or another metric (4%; n = 41). One or more references were cited for the NCD case definition by 49% of studies (n = 273/555), with the most common references being Larson et al. (1977) (n = 85), and McGuirk (2008) (n = 59). In the 555 included articles, 979 unique diarrhea-related outcomes were found, most commonly a binary categorization of calves having or not having diarrhea (49%; n = 483). Other articles reported statistical outcomes calculated from fecal scores (16%; n = 159), multiple diarrhea severities (10%; n = 95), or the age calves first developed NCD (8%; n = 76). This review characterized substantial heterogeneity among NCD case definitions and diarrhea-related outcomes, which limits interpretation and comparison of studies. Future work is required to develop and validate reporting standards for NCD to optimize knowledge synthesis and support rigorous and ethical calf health research.

Clinical Scoring Systems in the Newborn Calf: An Overview

Simple Summary

Clinical scores are gaining increasing popularity in veterinary medicine thanks to their multiple advantages, which include quickness, ease, and convenience of use. This review discusses the applications of some already-known clinical scores in newborn calf management at birth and during the first weeks of age. Clinical scores are employed to assess newborn calf viability and to diagnose and monitor neonatal calf diarrhea and respiratory diseases, helping the clinician promptly recognize calves needing medical assistance. This review discusses limitations pertaining to their use and encourages efforts towards a greater consistency in definition and validation.

Abstract

A scoring system is an instrument that enables the scorers, including farmers, technicians, and veterinarians, to adopt a systematic approach for diagnosis or monitoring, as it decreases bias and confounding and increases objectivity. Practically, it is a number assigned to a patient that correlates with a probability that a diagnosis can be confirmed or that a specific outcome will follow. This article examines the clinical scores designed or adapted to bovine medicine that aim to assess newborn calf viability and to diagnose and monitor neonatal calf diarrhea and respiratory diseases, helping the clinician promptly recognize calves needing medical assistance. Despite the large number of clinical scores described in the literature, these are still barely used in farm animal practice; possibly, the complexity of the scores and missing recommendations for intervention are reasons for their lack of popularity as well as the crosswise lack of consistency among scores designed for the same purpose. Further research is needed in this regard to increase scores validation and encourage their application in bovine calf neonatology.

Can apps be used to formulate fluid therapy plans in veterinary medicine?

BACKGROUND

Formulating sophisticated fluid therapy plans can be complicated and time consuming. Consequently, veterinarians in the field who lack experience, time, or confidence may formulate suboptimal fluid therapy plans.

OBJECTIVES

Compare conventional and app-guided fluid therapy plans for simulated cases of neonatal calf diarrhea.

PARTICIPANTS

Third and fourth year veterinary students (n = 55) from The University of Sydney.

METHODS

We developed a web app to assist fluid therapy formulation (http://calfaid.com) that was evaluated in a randomized case simulation trial. Participants were instructed to perform fluid therapy calculations and formulate an integrated fluid therapy plan for case scenarios using conventional methods and using the fluid therapy app. Responses were scored by a blinded study investigator using an a priori scoring guide and groups (conventional vs. app-guided) were compared using linear mixed models.

RESULTS

On average, total scores for app-guided fluid therapy calculations were 20.6% points higher (95% confidence interval [CI], 14.1-27.1) than calculations completed using the conventional method (88.2% vs. 67.5%, respectively). On average, total scores for app-guided integrated fluid therapy plans were 14.2% points higher (95% CI, 6.3-22.2; 65.8% vs. 51.2%). Eighty percent of respondents indicated they would prefer to use the app-guided method over the conventional method.

CONCLUSION AND CLINICAL IMPORTANCE

Our findings suggest that fluid therapy plans can be improved using apps.

The Antibiotic Treatment of Calf Diarrhea in Four European Countries: A Survey

Neonatal calves are commonly affected by diarrhea caused by different pathogens, but not always bacteria. Yet, antibiotics are routinely used as a treatment to an unknown extent. It was our goal to survey antibiotic use for the treatment of neonatal calf diarrhea in different countries and to identify influencing factors. A total of 873 farmers and veterinarians in Austria, Belgium, Portugal, and Scotland participated in a voluntary online survey. The data were analyzed using classification and regression tree analyses and chi² tests. Overall, 52.5% of the participants stated that they use antibiotics when treating neonatal calf diarrhea. Of those, 27% use them always, and 45% use highest priority critically important antibiotics. The most important factor differentiating antibiotic use practices was the country the participants were from, which could be due to regulatory differences between the countries. All antibiotic products stated were licensed for use in cattle, but several were not licensed for the treatment of diarrhea in calves. Our study shows that there is an urgent need for more scientific evidence to define best practices for the treatment of neonatal calf diarrhea. Furthermore, consensual criteria for antibiotic therapy must be defined, and targeted training for farmers and veterinarians must be provided.

Detection of Infectious Agents Causing Neonatal Calf Diarrhea on Two Large Dairy Farms in Yangxin County, Shandong Province, China

Neonatal calf diarrhea (NCD) is one of the most serious health challenges facing the livestock industry and has caused substantial economic losses due to increased morbidity and mortality rates. The present study investigated the main infectious pathogens causing NCD among cattle in Yangxin County, China. Sixty-nine fecal samples were collected from diarrheic newborn cattle and tested for infectious agents, including bovine rotavirus, bovine coronavirus, Escherichia coli K99, Cryptosporidium parvum, and Giardia lamblia, that cause NCD, as determined by rapid kit analysis and polymerase chain reaction (PCR) amplification. The PCR results showed that the percentages of samples that were positive for C. parvum, bovine rotavirus A, bovine coronavirus, and G. lamblia were 44.93, 36.23, 17.39, and 13.04%, respectively. The rapid kit analysis results showed that the prevalence of C. parvum, rotavirus, coronavirus, and G. lamblia was 52.17, 31.88, 28.98, and 18.84%, respectively. No E. coli K99 was detected by either method. The total positivity of the samples, as determined by PCR and rapid kit analysis, was 80.00 and 81.16%, respectively. No significant difference between the two methods was observed. The results of this study may help to establish a foundation for future research investigating the epidemiology of NCD in cattle and may facilitate the implementation of measures to control NCD transmission to cattle in Yangxin County, Shandong Province, China.

Intravenous and Oral Fluid Therapy in Neonatal Calves With Diarrhea or Sepsis and in Adult Cattle

Optimal fluid therapy protocols in neonatal calves and adult cattle are based on consideration of signalment, history, and physical examination findings, and individually tailored whenever laboratory analysis is available. Measurement of the magnitude of eye recession, duration of skin tenting in the lateral neck region, and urine specific gravity by refractometry provide the best estimates of hydration status in calves and cattle. Intravenous and oral electrolyte solutions (OES) are frequently administered to critically ill calves and adult cattle. Application of physicochemical principles indicates that 0.9% NaCl, Ringer's solution, and 5% dextrose are equally acidifying, lactated Ringer's and acetated Ringer's solution are neutral to mildly acidifying, and 1.3-1.4% sodium bicarbonate solutions are strongly alkalinizing in cattle. Four different crystalloid solutions are recommended for intravenous fluid therapy in dehydrated or septic calves and dehydrated adult cattle: (1) lactated Ringer's solution and acetated Ringer's solution for dehydrated calves, although neither solution is optimized for administration to neonatal calves or adult cattle; (2) isotonic (1.3%) or hypertonic (5.0 or 8.4%) solutions of sodium bicarbonate for the treatment of calves with diarrhea and severe strong ion (metabolic) acidosis and hyponatremia, and adult cattle with acute ruminal acidosis; (3) Ringer's solution for the treatment of metabolic alkalosis in dehydrated adult cattle, particularly lactating dairy cattle; and (4) hypertonic NaCl solutions (7.2%) and an oral electrolyte solution or water load for the rapid resuscitation of dehydrated neonatal calves and adult cattle. Much progress has been made since the 1970's in identifying important attributes of an OES for diarrheic calves. Important components of an OES for neonatal calves are osmolality, sodium concentration, the effective SID that reflects the concentration of alkalinizing agents, and the energy content. The last three factors are intimately tied to the OES osmolality and the abomasal emptying rate, and therefore the rate of sodium delivery to the small intestine and ultimately the rate of resuscitation. An important need in fluid and electrolyte therapy for adult ruminants is formulation of a practical, effective, and inexpensive OES.

D-Lactic Acid as a Metabolite: Toxicology, Diagnosis, and Detection

Two enantiomers of lactic acid exist. While L-lactic acid is a common compound of human metabolism, D-lactic acid is produced by some strains of microorganism or by some less relevant metabolic pathways. While L-lactic acid is an endogenous compound, D-lactic acid is a harmful enantiomer. Exposure to D-lactic acid can happen by various ways including contaminated food and beverages and by microbiota during some pathological states like short bowel syndrome. The exposure to D-lactic acid cannot be diagnosed because the common analytical methods are not suitable for distinguishing between the two enantiomers. In this review, pathways for D-lactic acid, pathological processes, and diagnostical and analytical methods are introduced followed by figures and tables. The current literature is summarized and discussed.

Determining the predictive capability of a Clinical Assessment Scoring Chart to differentiate severity of the clinical consequences of neonatal calf diarrhea relative to gold-standard blood gas analysis

Neonatal calf diarrhea (NCD) is a major problem to calf health worldwide, in terms of both morbidity and mortality. A five-point ordinal scale clinical assessment scoring (CAS) chart was utilized to assess calves suffering from NCD-related clinical abnormalities (acidosis and dehydration) on commercial farms. The objective of this research was to determine the predictive capability of this CAS chart against gold standard blood gas parameters, designed to assist farmers in the accurate assessment of the clinical consequences of NCD. A total of 443 diarrheic and non-diarrheic calves were enrolled in the study. The CAS chart rated a calf’s health from no clinical signs to varying degrees of clinical severity on a 0 (clinically normal) to 4 (grave) scale, based on clinical indicators including calf demeanour, ear position, mobility, suckle reflex, desire-to-feed, and enophthalmos. Blood gas analysis was conducted for individual calves, consisting of pH, base excess, Na⁺, K⁺, Ca²⁺, Cl⁻, glucose, total hemoglobin, bicarbonate, anion gap, and strong ion difference. Statistical evaluation was performed by comparison of the CAS score with blood gas profiles using ordinal logistic regression and a non-parametric estimation of the Receiver Operating Characteristics (ROC). The ROC analysis indicated that the CAS chart had acceptable specificity (>95%) with low sensitivity (<60%) in differentiating clinically normal from acidotic/dehydrated cases. Assessment of individual severity classes indicated that the chart can predict and differentiate both clinically normal and advanced cases from the other severity classes (peak estimations >80%) but had reduced accuracy in differentiating mild and moderate cases (peak estimations >50%). The chart, as presented, provides a simple tool to differentiate clinically normal from calves suffering the consequences of diarrhea, but fails to accurately differentiate severity for NCD related acidosis and dehydration. Further efforts are required to enhance the sensitivity and differential diagnostic value of this type of chart.

Comparison of oral, intravenous, and subcutaneous fluid therapy for resuscitation of calves with diarrhea

Neonatal diarrhea remains the primary cause of mortality in dairy calves around the world, and optimal treatment protocols are needed. The main goals of therapy are to restore hydration and electrolyte concentrations, correct strong ion (metabolic) acidemia, and provide nutritional support. Administration of oral electrolyte solutions (OES) has long been the primary method used to treat neonatal diarrhea in humans and calves because OES are capable of addressing each of the primary goals of therapy. In calves with moderate dehydration, we hypothesized that oral electrolytes would be as good as or better than small volumes of intravenous (IV) or subcutaneous (SC) fluids. Therefore, the main goal of this study was to compare the ability of a commercially available oral electrolyte solution (OES) administered alone or in combination with hypertonic saline with small volumes of IV or SC fluid therapy to resuscitate calves with diarrhea. Thirty-three Holstein calves from 5 to 14 d of age were utilized in this clinical trial. Diarrhea and dehydration were induced by adding sucrose to the milk replacer. In addition, hydrochlorothiazide and spironolactone were given orally and furosemide intramuscularly. Depression status, clinical hydration scores, fecal consistency, and body weight were recorded at regular intervals. Treatment began when calves had severe diarrhea and had a decrease in plasma volume of at least 10%. Calves were randomly assigned to 1 of 4 treatment groups of 8 to 9 calves per group: (1) OES; (2) OES with hypertonic saline (4 mL/kg, IV); (3) IV fluids (lactated Ringer's, 2 L); or (4) SC fluids (lactated Ringer's, 2 L). Treatments were given at 0 and 12 h. Changes in plasma volume, blood pH, electrolyte levels, and physical examination scores were determined before therapy and again at 1, 2, 4, 8, and 12 h after each treatment. All 4 treatments were ultimately successful in improving hydration as well as increasing blood pH; however, animals in both groups that received OES had much faster resuscitation than those in either the IV or SC fluid group. In conclusion, oral electrolyte products remain the gold standard for resuscitating diarrheic calves with moderate dehydration and acidemia and will likely perform better than small volumes of IV lactated Ringer's solution. Subcutaneous fluids by themselves are a poor treatment option and should be only be used as supportive therapy following the initial correction of hypovolemia and metabolic acidosis.

Diagnosis and Treatment of Infectious Enteritis in Neonatal and Juvenile Ruminants

Common causes of infectious enteritis in neonate and juvenile ruminants include viral, bacterial, and protozoal pathogens. The most common presenting sign in ruminants with infectious enteritis is diarrhea. Diagnosis of the cause of enteritis has important zoonotic and herd health implications. Severity of clinical signs with similar pathogens may differ between calves and small ruminants. Treatment of enteritis involves supportive care to correct fluid and electrolyte imbalances, provision of nutritional support for neonates, prevention and treatment of endotoxemia or sepsis, and pathogen-specific treatments when relevant and available.

Clinical signs, profound acidemia, hypoglycemia, and hypernatremia are predictive of mortality in 1,400 critically ill neonatal calves with diarrhea

Profound acidemia impairs cellular and organ function and consequently should be associated with an increased risk of mortality in critically ill humans and animals. Neonatal diarrhea in calves can result in potentially serious metabolic derangements including profound acidemia due to strong ion (metabolic) acidosis, hyper-D-lactatemia, hyper-L-lactatemia, azotemia, hypoglycemia, hyperkalemia and hyponatremia. The aim of this retrospective study was to assess the prognostic relevance of clinical and laboratory findings in 1,400 critically ill neonatal calves with diarrhea admitted to a veterinary teaching hospital. The mortality rate was 22%. Classification tree analysis indicated that mortality was associated with clinical signs of neurologic disease, abdominal emergencies, cachexia, orthopedic problems such as septic arthritis, and profound acidemia (jugular venous blood pH < 6.85). When exclusively considering laboratory parameters, classification tree analysis identified plasma glucose concentrations < 3.2 mmol/L, plasma sodium concentrations ≥ 151 mmol/L, serum GGT activity < 31 U/L and a thrombocyte count < 535 G/L as predictors of mortality. However, multivariable logistic regression models based on these laboratory parameters did not have a sufficiently high enough sensitivity (59%) and specificity (79%) to reliably predict treatment outcome. The sensitivity and specificity of jugular venous blood pH < 6.85 were 11% and 97%, respectively, for predicting non-survival in this study population. We conclude that laboratory values (except jugular venous blood pH < 6.85) are of limited value for predicting outcome in critically ill neonatal calves with diarrhea. In contrast, the presence of specific clinical abnormalities provides valuable prognostic information.

Effect of Intravenous Small-Volume Hypertonic Sodium Bicarbonate, Sodium Chloride, and Glucose Solutions in Decreasing Plasma Potassium Concentration in Hyperkalemic Neonatal Calves with Diarrhea

Background

Hyperkalemia is a frequently observed electrolyte imbalance in dehydrated neonatal diarrheic calves that can result in skeletal muscle weakness and life‐threatening cardiac conduction abnormalities and arrhythmias.

Hypothesis

Intravenous administration of a small‐volume hypertonic NaHCO₃ solution is clinically more effective in decreasing the plasma potassium concentration (cK) in hyperkalemic diarrheic calves than hypertonic NaCl or glucose solutions.

Animals

Twenty‐two neonatal diarrheic calves with cK >5.8 mmol/L.

Methods

Prospective randomized clinical trial. Calves randomly received either 8.4% NaHCO₃ (6.4 mL/kg BW; n = 7), 7.5% NaCl (5 mL/kg BW; n = 8), or 46.2% glucose (5 mL/kg BW; n = 7) IV over 5 minutes and were subsequently allowed to suckle 2 L of an electrolyte solution. Infusions with NaHCO₃ and NaCl provided an identical sodium load of 6.4 mmol/kg BW.

Results

Hypertonic NaHCO₃ infusions produced an immediate and sustained decrease in plasma cK. Hypertonic glucose infusions resulted in marked hyperglycemia and hyperinsulinemia, but cK remained unchanged for 20 minutes. Between 30 and 120 minutes after initiation of treatment, the most marked decrements in cK from baseline occurred in group NaHCO₃, which were significantly (P < .05) larger during this period of time than in calves in group NaCl, but not group glucose. After 120 minutes, the mean decrease in cK from baseline was −26 ± 10%, −9 ± 8%, and −22 ± 6% in groups NaHCO₃, NaCl, and glucose, respectively.

Conclusions/Clinical Importance

Small‐volume hypertonic NaHCO₃ infusions appear to have clinical advantages for the rapid resuscitation of hyperkalemic diarrheic calves, compared to hypertonic NaCl or glucose solutions.

Risk factors for the development of hypokalemia in neonatal diarrheic calves

Background

Neonatal diarrheic calves have a clear negative potassium balance because of intestinal losses and decreased milk intake but in the presence of acidemia, they usually show normokalemic or hyperkalemic plasma concentrations.

Objectives

To assess whether marked hypokalemia occurs in response to the correction of acidemia and dehydration and to identify factors that are associated with this condition.

Animals

Eighty‐three calves with a clinical diagnosis of neonatal diarrhea.

Methods

Prospective cohort study. Calves were treated according to a clinical protocol using an oral electrolyte solution and commercially available packages of 8.4% sodium bicarbonate, 0.9% saline and 40% dextrose infusion solutions.

Results

The proportion of hypokalemic calves after 24 hours of treatment (19.3%) was twice as great as it was on admission to the hospital. Plasma K⁺ after 24 hours of treatment was not significantly correlated to venous blood pH values at the same time but positively correlated to venous blood pH values on admission (r = 0.51, P < .001). Base excess on admission (Odds ratio [OR] = 0.81, 95% confidence interval [CI] = 0.70–0.94), duration of diarrhea (OR = 1.37, 95% CI = 1.05–1.80), milk intake during hospitalization (OR = 0.54, 95% CI = 0.37–0.79) and plasma sodium concentrations after 24 hours (OR = 1.12, 95% CI = 1.01–1.25) were identified to be independently associated (P < .05) with a hypokalemic state after 24 hours of treatment.

Conclusions and Clinical Importance

Findings of this study suggest that marked depletion of body potassium stores is evident in diarrheic calves that suffered from marked metabolic acidosis, have a low milk intake and a long history of diarrhea.

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.

Effects of alkalinization and rehydration on plasma potassium concentrations in neonatal calves with diarrhea

Background

Increased plasma potassium concentrations (K⁺) in neonatal calves with diarrhea are associated with acidemia and severe clinical dehydration and are therefore usually corrected by intravenous administration of fluids containing sodium bicarbonate.

Objectives

To identify clinical and laboratory variables that are associated with changes of plasma K⁺ during the course of treatment and to document the plasma potassium‐lowering effect of hypertonic (8.4%) sodium bicarbonate solutions.

Animals

Seventy‐one neonatal diarrheic calves.

Methods

Prospective cohort study. Calves were treated according to a clinical protocol using an oral electrolyte solution and commercially available packages of 8.4% sodium bicarbonate (250–750 mmol), 0.9% saline (5–10 L), and 40% dextrose (0.5 L) infusion solutions.

Results

Infusions with 8.4% sodium bicarbonate solutions in an amount of 250–750 mmol had an immediate and sustained plasma potassium‐lowering effect. One hour after the end of such infusions or the start of a sodium bicarbonate containing constant drip infusion, changes of plasma K⁺ were most closely correlated to changes of venous blood pH, plasma sodium concentrations and plasma volume (r = −0.73, −0.57, −0.53; P < .001). Changes of plasma K⁺ during the subsequent 23 hours were associated with changes of venous blood pH, clinical hydration status (enophthalmos) and serum creatinine concentrations (r = −0.71, 0.63, 0.62; P < .001).

Conclusions and Clinical Importance

This study emphasizes the importance of alkalinization and the correction of dehydration in the treatment of hyperkalemia in neonatal calves with diarrhea.

Advances in prevention and therapy of neonatal dairy calf diarrhoea: a systematical review with emphasis on colostrum management and fluid therapy

Neonatal calf diarrhoea remains the most common cause of morbidity and mortality in preweaned dairy calves worldwide. This complex disease can be triggered by both infectious and non-infectious causes. The four most important enteropathogens leading to neonatal dairy calf diarrhoea are Escherichia coli, rota- and coronavirus, and Cryptosporidium parvum. Besides treating diarrhoeic neonatal dairy calves, the veterinarian is the most obvious person to advise the dairy farmer on prevention and treatment of this disease. This review deals with prevention and treatment of neonatal dairy calf diarrhoea focusing on the importance of a good colostrum management and a correct fluid therapy.