==== Front
J Vet Med SciJ. Vet. Med. SciJVMSThe Journal of Veterinary Medical Science0916-72501347-7439The Japanese Society of Veterinary Science 2986302818-010910.1292/jvms.18-0109Internal MedicineFull PaperHypoglycemia and failure of respiratory compensation are risk factors for mortality in diarrheic calves in Hokkaido, northern Japan TSUKANO Kenji 12*SARASHINA Shinya 3SUZUKI Kazuyuki 11) School of Veterinary Medicine, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu, Hokkaido 069-8501, Japan2) Minami-Hokkaido Agricultural Mutual Relief Association, 74-2 Higashimae, Hokuto, Hokkaido 041-1214, Japan3) Minami-Hokkaido Agricultural Mutual Relief Association, 25-16 Misugicho, Yakumo, Futami-gun, Hokkaido 049-3114, Japan* Correspondence to: Tsukano, K.: tukano_kenzi@minami-hkd-nosai.or.jp04 6 2018 7 2018 80 7 1159 1164 01 3 2018 20 5 2018 ©2018 The Japanese Society of Veterinary Science2018This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives (by-nc-nd) License. (CC-BY-NC-ND 4.0:  https://creativecommons.org/licenses/by-nc-nd/4.0/)The aim of present study was to identify risk factors among laboratory findings for mortality in calves with diarrhea. A retrospective analysis was conducted utilizing medical records of
221 diarrheic calves (10.4 ± 3.7 days old) with no concurrent severe disorders that were treated with intravenous fluid therapy from the initial examination. Thirty-eight of the diarrheic
calves (17.2%) died within 35 days from the initial examination. Multivariate logistic regression analysis indicated that hypoglycemia (OR 3.09; 95% CI 1.22–7.87; P=0.02)
and failure of respiratory compensation (OR 2.63; 95% CI 1.05–6.62; P=0.04) were the major risk factors associated with a negative outcome in diarrheic calves. According to
the Kaplan-Meyer analysis, diarrheic calves with hypoglycemia and/or failure of respiratory compensation had a significantly shorter survival than calves without these factors.

calfdiarrheamortalityrisk factor
==== Body
Diarrhea in neonatal calves remains the leading cause of mortality. Diarrhea leads to overall loss of not only electrolytes and water, but also decreases absorption of carbohydrates, lipids,
and amino acids in calves [6]. As a result, calves experience acute symptoms of dehydration, electrolyte imbalance, metabolic acidosis, and negative energy
balance. Intravenous (IV) fluid therapy is important for decreasing the mortality associated with diarrhea in calves. Based on current knowledge, IV fluid therapy must satisfy the following
three requirements: (1) supply sufficient sodium to normalize the extracellular fluid volume; (2) provide an alkalinizing agent to correct the metabolic acidosis; and (3) provide energy because
most calves with diarrhea are in a state of negative energy balance [6].

Previous studies demonstrated that increased serum urea, hematocrit, chloride concentrations [13], acidemia, hypoglycemia, and hypernatremia [30] were risk factors for mortality in diarrheic calves. Trefz et al. [29] indicated that severe
hypoglycemia was present in only 6.3% of cases, but resulted in a mortality rate of 79.4% in 10,060 neonatal hospitalized calves. The high mortality rate in calves with hypoglycemia can be
explained by serious health conditions associated with this metabolic imbalance, including malnutrition [29]. Similarly, diarrhea remains a major cause of
death in children under the age of five years worldwide [21]. Talbert et al. [25] reported that
hyponatremia, hypoxia, hypokalemia, and malnutrition were risk factors for death, and children with malnutrition due to diarrhea in particular had a higher risk of death. [23, 25, 28]. Protein energy malnutrition was found to be a serious issue associated with death in
diarrheic children [27]. Bacterial infection is more common with severe malnutrition, and is thought to occur, in part, because of immunosuppressive
effects and the loss of the protective mucosal barrier in the gastrointestinal tract [8]. In an effort to address the high child mortality, the World Health
Organization (WHO) provides a guideline to improve management for children with malnutrition [32]. Therefore, many pediatric hospitals conforming to the
WHO guidelines have succeeded in reducing the mortality of children with malnutrition due to diarrhea [3, 12].

Although our understanding of the pathophysiology [14] and fluid therapy, especially replacement of fluid loss and correction of acid-base balance [6, 24], for diarrheic calves has progressed, mortality rates have remained unchanged for several decades [18, 19, 30]. This suggests the importance of the next step for treatment of
diarrheic calves. However, there is a lack of systematic reporting of laboratory data to identify risk factors that allow for comparative studies of the burden, spectrum, and outcome of
diarrheic calves. Identification of risk factors will help form prospective treatments or change management to improve outcome. Indeed, epidemiologic research may be useful to find new methods,
but there is very little epidemiologic research to advance treatments for diarrheic calves. The aim of present study was to identify risk factors among laboratory findings in calves with
diarrhea. These data may be useful information for treatment of calves with diarrhea.

MATERIALS AND METHODS
All procedures were in accordance with the National Research Council Guidelines for the Care and Use of Laboratory Animals (National Academy Press, 1996). A retrospective analysis was
conducted utilizing medical records of 221 diarrheic calves (10.4 ± 3.7 days old) with no concurrent severe disorder that were treated with intravenous fluid therapy from the initial
examination at the Minami Hokkaido Agricultural Mutual Relief Association, Hokkaido (140°E, 42°N) between January 2015 and September 2017. Of these calves, 96 (43.4%) were Holstein, 65 (29.4%)
were the first filial generation of a Japanese Black, and 60 (27.1%) were Japanese Black. Most of these calves had been treated such as oral electrolyte solutions, antimicrobial and probiotics
in farms before medical treatment by veterinarian. Clinical signs of eyeball recession into the orbit and impaired central nervous system function, including absent suckling reflex, ataxia,
and coma, were the main observations for these calves. All calves received an intravenous (IV) fluid therapy consisting of saline, acetate Ringer’s, 7.0% sodium bicarbonate, and glucose from
the initial examination. The IV fluid therapy was continued until recovery from clinical signs of metabolic acidosis and dehydration. In addition, antimicrobial or anti-inflammatory therapy
was carried out for 195 (88.2%) and 83 (37.6%) calves, respectively. The IV fluid therapy or supportive therapy was continued until calves were discharged in a healthy state.

Normally, all calves were offered two feedings of milk at the rate of 5% of body weight per feeding in the morning (a.m. 5:00−a.m. 8:00) and afternoon (p.m. 5:00−p.m. 8:00), but 205 of the
diarrheic calves (92.8%) in this survey fall into anorexia. The amount of last milk which calves drunk is unknown, but blood collections was done at least two hours after the providing milk
for calves. Venous blood samples were anaerobically collected in a heparinized 1 ml syringe from the left jugular vein, and the tips of the syringes capped after collection
before the IV fluid therapy. All calves underwent a blood analysis including blood pH, carbon dioxide partial pressure (PCO2), bicarbonate (HCO3−), base excess
(BE), anion gap (AG), sodium (Na), potassium (K), chloride (Cl), urea (BUN), glucose (Glu), hematocrit (Ht), and hemoglobin (Hb) concentrations using an automatic gas analyzer (i-STAT 1,
Abbott Lab, Princeton, IL, U.S.A.) and i-STAT cartridge (i-STAT EC8+ Cartridge, Abbott Lab) at the initial examination.

Statistical analysis: Statistical analysis was conducted using Excel Toukei 2010 (SSRI, Osaka, Japan). Normally distributed data are reported as the mean ± standard deviation
(SD), and non-normally distributed data (total treatment periods, plasma glucose concentration and blood pH) are expressed as the median and ranges. Calves were divided into two groups based
on the survival period (until 60 days) from the initial examination (Survival group or Non-survival group). The student’s t-test or Mann-Whitney U-test after
the F-test was used for comparisons of blood data between groups. Multivariate association between categorized variables and outcome of therapy was evaluated by logistic
regression analysis with calculation of odds ratios (OR) and associated 95% confidence intervals (95% CI). In addition, the overall survival time (OST) was calculated as the time between the
initiation of treatment and death resulting from diarrhea. The OST curves were estimated by Kaplan-Meyer statistics for the different groups of diarrheic calves with or without risk factors
for mortality. The OST among different groups of diarrheic calves was compared using the Bonferroni test after the log-rank test. ROC curves were also used to characterize the sensitivity and
specificity of each parameter with respect to changes associated with a negative outcome. The optimal cut-off point for each test was calculated by the Youden index [2]. The Youden index (J) is defined as the maximum vertical distance between the ROC curve and diagonal or chance line, and is calculated as J=maximum
[sensitivity+specificity−1]. The cut-off point on the ROC curve corresponding to J was regarded as the optimal cut-off point [2]. The significance level
was set at P<0.05.

RESULTS
Thirty-eight of the diarrheic calves (17.2%) died until 60 days from the initial examination. Therefore, 183 and 38 diarrheic calves were in the survival group and non-survival group,
respectively. The survival rate of the 221 diarrheic calves in this survey was 82.8% (183/221). The total treatment periods were significantly longer in the non-survival group (7.0 days, min
to max, 2–34 days) than those in the survival group (5.0 days, 1–22 days, P<0.05). During the IV fluid therapy for the diarrheic calves from the initial examination, the
total fluid volume was significantly higher in the non-survival group than in the survival group (5,186.8 ± 1,581.9 vs 4,344.6 ± 1,416.1 ml, P=0.006).
However, there were no significant differences in the volume of 7.0% sodium bicarbonate solution (437.6 ± 187.7 vs 400.9 ± 197.0 ml, P>0.05), glucose (82.1
± 62.5 vs 81.8 ± 61.8 g, P>0.05), and glucose per total fluid volume (1.6 ± 1.2 vs 2.0 ± 1.5%, P>0.05) between groups. Total IV fluid therapy periods
were significantly longer (P<0.001) in the non-survival group (5.0 ± 1.0 days) than in the survival group (2.4 ± 2.0 days).

The results of the blood analysis are summarized in Table 1Table 1. Laboratory findings for survival and non-survival groups
	Survival	Non-survival	P-value	
(n=183)	(n=38)	
Na	(mmol/l)	132.1 ± 8.7	135.5 ± 10.4	0.04	
K	(mmol/l)	5.6 ± 1.3	6.1 ± 1.6	NS	
Cl	(mmol/l)	106.0 ± 10.0	109.8 ± 11.8	0.04	
BUN	(mg/dl)	48.9 ± 37.5	60.4 ± 38.4	NS	
Glu	(mg/dl)	82.5 (34–192)	70.5 (19–263)	0.02	
Ht	(%)	34.2 ± 8.7	37.1 ± 9.7	NS	
Hb	(g/dl)	11.6 ± 2.9	12.6 ± 3.3	NS	
pH		7.11 (6.69–7.43)	7.05 (6.66–7.45)	0.04	
PCO2	(mmHg)	42.6 ± 11.8	50.0 ± 12.6	0.001	
HCO3−	(mmol/l)	14.6 ± 7.0	14.8 ± 6.4	NS	
BE	(mmol/l)	–14.9 ± 8.8	–15.7 ± 8.9	NS	
AG	(mmol/l)	17.3 ± 4.5	16.8 ± 4.7	NS	
. The plasma Na (P=0.04) and Cl (P=0.04) concentrations, and PCO2 (P=0.001) were significantly higher in the
non-survival group. On the other hand, blood pH (P=0.04) and plasma glucose concentrations (P=0.02) were significantly lower in the non-survival group. There
were no other significant differences in the blood analysis data.

The following blood analysis parameters were categorized at the initial examination for multivariate logistic regression analysis based on the reference values (ref) in Table 2Table 2. Risk factors among laboratory findings for mortality in diarrheic calves
Variable (n=221)	Variable category	Odds ratio	95% confidence interval	P-value	Reference	
Sodium concentration (mmol/l)	138.8–144.0	1.00	-	-	 [15]	
 <138.8	0.44	0.16, 1.25	NS	
 >144.0	0.43	0.09, 1.93	NS	
Chloride concentration (mmol/l)	100.3–107.0	1.00	-	-	 [15]	
 <100.3	0.47	0.14, 1.55	NS	
 >107.0	0.95	0.34, 2.64	NS	
Glucose concentration (mg/dl)	68.0–90.0	1.00	-	-	 [22]	
 <68.0	3.09	1.22, 7.87	0.02	
 >90.0	1.12	0.41, 3.07	NS	
Blood pH	≥7.20	1.00	-	-	 [5]	
 <7.20	1.64	0.58, 4.68	NS	
Carbon dioxide partial pressure (mmHg)	39.8–50.3	1.00	-	-	 [7]	
 <39.8	0.49	0.18, 1.32	NS	
 >50.3	2.63	1.05, 6.62	0.04	
. Multivariate logistic regression analysis indicated that hypoglycemia (OR 3.09; 95% CI 1.22–7.87; P=0.02) and failure of respiratory compensation (OR 2.63; 95%
CI 1.05–6.62; P=0.04) were the major risk factors associated with a negative outcome in diarrheic calves. However, no differences were found for blood pH or plasma Na and Cl
concentrations.

Figure 1Fig. 1. Graphs depicting the overall survival time (OST) from the initiation of treatment in diarrheic calves with or without risk factors associated with a negative outcome by Kaplan-Meyer
analysis. The OST among different groups was compared using the Bonferroni test after the log-rank test. *; P<0.05 vs no hypoglycemia and success of
respiratory compensation.

 shows the OST from the initiation of treatment for diarrheic calves with or without risk factors associated with a negative outcome. At the end point of the survey 60 days from the
initial examination, 8 of 111 (7.2%) diarrheic calves without risk factors had died. On the other hand, 13 of 51 (25.5%) and 12 of 48 (25.0%) diarrheic calves with risk factors for
hypoglycemia (<68.0 mg/dl, [15]) and failure of respiratory compensation (>50.3 mmHg, [7]),
respectively, had died. Similarly, at the end point of the survey, 5 of 11 (45.5%) diarrheic calves demonstrated that hypoglycemia and failure of respiratory compensation were the major risk
factors for mortality. Therefore, based on the survival estimated by Kaplan-Meyer analysis, diarrheic calves with risk factors had a significantly shorter (P<0.05) survival
than calves without.

The areas under the ROC curve for PCO2 and plasma glucose concentration were 0.678 (P<0.01) and 0.384 (P<0.05), respectively. The proposed
diagnostic cut-off point for PCO2 and plasma glucose concentration for non-survival progression of diarrheic calves were set at >46.9 mmHg and <71.5 mg/dl,
respectively (Fig. 2Fig. 2. ROC curves for partial pressure of carbon dioxide and serum glucose concentration for non-survival progression of diarrheic calves. The optimal cut-off point for the test was calculated
by the Youden index (J). Open Circle: Cut-off point.

). The sensitivity and specificity of the proposed diagnostic cut-offs for PCO2 were 68.4 and 68.9%, respectively. The sensitivity and specificity of the proposed diagnostic
cut-offs for plasma glucose concentrations were 53.3 and 70.5%, respectively. As a result of the multivariate logistic regression analysis using the cut-off values for a negative outcome in
diarrheic calves, hypoglycemia (OR 4.11; 95% CI 1.87–9.04; P<0.001) and failure of respiratory compensation (OR 6.07; 95% CI 2.71–13.6; P<0.001) were
finally extracted.

DISCUSSION
In this survey, we demonstrated that hypoglycemia and failure of respiratory compensation are the major risk factors associated with a negative outcome in diarrheic calves by multivariate
logistic regression analysis. According to Kaplan-Meyer statistics, diarrheic calves with hypoglycemia and/or failure of respiratory compensation had a significantly shorter survival than
calves without.

The i-STAT Portable Clinical Analyzer, a point-of-care testing has been shown to be valuable in the early diagnosis and management in critically ill patients [1]. Previous studies demonstrated that agreement between i-STAT Portable Clinical Analyzer for point-of-care testing with standard laboratory testing in the analysis of electrolytes,
glucose, blood pH and gases was goods [1, 20]. In addition, i-STAT portable clinical analyzer performed similarly
to the standard clinical laboratory systems for evaluation of glucose concentrations in horses [11]. Therefore the laboratory findings in this survey
were valid.

In this survey, we adopted cut-off value for hypoglycemia of diarrheic calves was set at <68.0 mg/dl [15]. Large-scale epidemiology
investigation demonstrated that plasma glucose concentration of non-survival diarrheic calves (median: 72.1 mg/dl) were significantly lower than those of survival diarrheic
calves (median: 79.3 mg/dl) [30]. In addition, our present survey proposed diagnostic cut-off point for plasma glucose concentration for
non-survival progression of diarrheic calves was set at <71.5 mg/dl. Furthermore previous study adopted similar reference range (79.3–124.3 mg/dl) for
diarrheic calves with hypoglycemia [29]. Therefore it seems that the cut-off value that we adopted is appropriate to diagnose hypoglycemia.

Trefz et al. [29] previously reported that hypoglycemia was associated with a poor survival rate in calves. Furthermore, Tennant
et al. [26] found that diarrheic calves with severe hypoglycemia (less than 40 mg/dl) were almost always extremely
dehydrated. Based on hematocrit (P=0.08) and hemoglobin (P=0.08) concentrations, the non-survival group tended to become dehydrated more often than the
survival group in this survey. Dehydration causes anaerobic metabolism, decreasing tissue oxygen levels and decreased glucose oxidation, resulting in anaerobic metabolism and inefficient
utilization of glucose [17]. Indeed, the addition of glucose to IV fluid solutions is widely used to provide energy [6], but it is important to improve the glucose efficiency to correct dehydration in diarrheic calves.

Hypoglycemia has been reported in diarrheic calves that were weak, lethargic, or comatose [26] and usually occurs in the terminal stages of the disease
[16]. The mean fecal fat content was higher in calves with diarrhea than in healthy calves, and the mean caloric uptake from milk was decreased by 31%
in diarrheic calves compared with healthy calves. Thus, the negative energy balance continues [33]. In addition, recent studies demonstrated that
diarrheic calves developed severe proteolysis and lipolysis [9, 31]. This suggests that diarrheic calves need to
more energy for maintenance because malnutrition is serious in diarrheic calves with hypoglycemia [29]. As malnutrition causes marked physiological and
metabolic changes, malnourished animals respond poorly to treatment. Treatment or prevention of hypoglycemia and hypothermia, and correction of micronutrient deficiencies are the main topics
in the WHO guidelines for the management of severe malnutrition [32]. Similarly, IV infusion in diarrheic calves should contain glucose in addition to
amino acids and lipids, but there is very little research on providing nutritional support to diarrheic calves. Parenteral nutrition (PN) has been widely adopted in human care since the late
1960’s [10]. PN has been used for patients with inappropriate oral feeding or any medical condition that leads to gastrointestinal failure. PN is usually
composed of a dilute solution of amino acids, glucose, and micronutrients. Therefore, greater concentrations of nutrients can be provided. Moreover, PN infusion therapy may be useful for
treatment of diarrheic calves exhibiting negative energy balance compared with classical glucose solution therapy.

In general, respiratory compensation of metabolic disorders occurs rapidly. Patients with metabolic acidosis have a base excess value of zero, usually due to compensatory respiratory
alkalosis [4]. The functional capacity of respiratory compensation of acidotic disorders in calves was reported around the same time as for humans [7]. In this survey, multivariate logistic regression analysis demonstrated that diarrheic calves with failure of respiratory compensation have a poor
prognosis. However, we only selected diarrheic calves with no concurrent severe disorders such as pneumonia or bronchitis. One reason for the failure of respiratory compensation in calves may
be severe dehydration [7]. We proposed a diagnostic cut-off point for PCO2 for non-survival progression of diarrheic calves, and multivariate
logistic regression analysis using the cut-off values for PCO2 resulted in a higher OR than when using the previous value. Respiratory compensation likely causes respiratory
alkalosis in calves with metabolic acidosis, thus it may be necessary to set a lower value for PCO2. However, there are few studies on respiratory compensation in calves with
metabolic acidosis [7]. Our data may be useful for respiratory compensation in calves with metabolic acidosis.

We found that hypoglycemia and failure of respiratory compensation were the major risk factors associated with a negative outcome in diarrheic calves. In diarrheic calves, treatment seems to
be unsuccessful when ventilatory deficiency occurs. The IV fluid therapy for the diarrheic calves with or without hypoglycemia in the initial examination, there were no significant differences
in the volume of the total fluid (4,513.7 ± 1,530.8 vs 4,479.8 ± 1,464.8 ml, P>0.05), 7.0% sodium bicarbonate solution (440.8 ± 184.0 vs 396.6 ± 197.0
ml, P>0.05), glucose (91.9 ± 66.3 vs 77.6 ± 59.8 g, P>0.05), and glucose per total fluid volume (2.0 ± 1.3 vs 1.8 ± 1.5%,
P>0.05) between groups, respectively. As we have demonstrated, it seems that veterinarians paid no attention to hypoglycemia. However, as hypoglycemia has a higher risk
of death, diarrheic calves with hypoglycemia require more careful medical attention during their recovery from diarrhea and need nutritional management for treatment to progress
appropriately.

This study was supported by a Grant-in-Aid for Science Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (no. 26450431) and a Grant-in-aid from the Ito
Foundation.
==== Refs
REFERENCES
1 Adekola O. O. Irurhe N. K. Meka I. A. Akanmu N. O. Menkiti I. D. Udenze I. C. Awolola N. A.  2013 . The agreement of point-of-care and standard laboratory electrolyte and glucose analysis in critically ill patients in a sub-Saharan tertiary
teaching hospital . Nig. Q. J. Hosp. Med. 23 : 58 –64 . 24579497 
2 Akobeng A. K.  2007 . Understanding diagnostic tests 3: Receiver operating characteristic curves . Acta
Paediatr. 96 : 644 –647 . doi: 10.1111/j.1651-2227.2006.00178.x 17376185 
3 Ashworth A. Chopra M. McCoy D. Sanders D. Jackson D. Karaolis N. Sogaula N. Schofield C.  2004 . WHO guidelines for management of severe malnutrition in rural South African hospitals: effect on case fatality and the influence of
operational factors . Lancet 363 : 1110 –1115 . doi: 10.1016/S0140-6736(04)15894-7 15064029 
4 Baer D. M.  1964 . Acid base disorders. The clinical use of the Astrup Method of determining pH, PCO2 and base excess .
Calif. Med. 101 : 439 –444 . 14232162 
5 Berchtold J.  1999 . Intravenous fluid therapy of calves . Vet. Clin. North Am. Food Anim.
Pract. 15 : 505 –531, vi . doi: 10.1016/S0749-0720(15)30161-4 10573809 
6 Berchtold J.  2009 . Treatment of calf diarrhea: intravenous fluid therapy . Vet. Clin. North Am. Food Anim.
Pract. 25 : 73 –99, vi . doi: 10.1016/j.cvfa.2008.10.001 19174284 
7 Berchtold J. Hartmann H. Hofmann W.  2000 . [Significance of respiratory compensation in acidosis in calves] . Dtsch. Tierarztl.
Wochenschr. 107 : 10 –16  (in German) . 10689793 
8 Brewster D. R. Manary M. J. Menzies I. S. O’Loughlin E. V. Henry R. L.  1997 . Intestinal permeability in kwashiorkor . Arch. Dis. Child. 76 :
236 –241 . doi: 10.1136/adc.76.3.236 9135265 
9 Bozukluhan K. Merhan O. Gokce H. I. Deveci H. A. Gokce G. Ogun M. Marasli S.  2017 . Alterations in lipid profile in neonatal calves affected by diarrhea . Vet.
World 10 : 786 –789 . doi: 10.14202/vetworld.2017.786-789 28831223 
10 Chang I. F. Sorof T. A. Nguyen N. Y. T.  2006  Chapter 27 Pharmacy considerations in pediatric parenteral nutrition. pp. 347−358. In: Pediatric Nutrition Support (Baker, S. S., Baker, R.
D. and Davis, A. M. eds.), Jones & Bartlett Pub, Sudbury.
11 Dechant J. E. Symm W. A. Nieto J. E.  2011 . Comparison of pH, lactate, and glucose analysis of equine synovial fluid using a portable clinical analyzer with a bench-top blood gas
analyzer . Vet. Surg. 40 : 811 –816 . 21770979 
12 Duke T. Kelly J. Weber M. English M. Campbell H.  2006 . Hospital care for children in developing countries: clinical guidelines and the need for evidence . J. Trop.
Pediatr. 52 : 1 –2 . doi: 10.1093/tropej/fmk006 16415297 
13 Fayet J. C. Overwater J.  1978 . Prognosis of diarrhoea in the newborn calf: statistical analysis of blood biochemical data . Ann. Rech.
Vet. 9 : 55 –61 . 707965 
14 Foster D. M. Smith G. W.  2009 . Pathophysiology of diarrhea in calves . Vet. Clin. North Am. Food Anim.
Pract. 25 : 13 –36, xi . doi: 10.1016/j.cvfa.2008.10.013 19174281 
15 Kasari T. R. Naylor J. M.  1984 . Metabolic acidosis without clinical signs of dehydration in young calves . Can. Vet.
J. 25 : 394 –399 . 17422463 
16 Kasari T. R. Naylor J. M.  1986 . Further studies on the clinical features and clinicopathological findings of a syndrome of metabolic acidosis with minimal dehydration in
neonatal calves . Can. J. Vet. Res. 50 : 502 –508 . 3024795 
17 Levenson S. M. Einheber A. Malm O. J.  1961 . Nutritional and metabolic aspects of shock . Fed. Proc. 20 
 Suppl 9 : 99 –140 . 13761350 
18 Lorenz I.  2004 . Influence of D-lactate on metabolic acidosis and on prognosis in neonatal calves with diarrhoea . J. Vet. Med.
A Physiol. Pathol. Clin. Med. 51 : 425 –428 . doi: 10.1111/j.1439-0442.2004.00662.x 15610486 
19 Naylor J. M.  1989 . A retrospective study of the relationship between clinical signs and severity of acidosis in diarrheic calves .
Can. Vet. J. 30 : 577 –580 . 17423372 
20 Papadea C. Foster J. Grant S. Ballard S. A. Cate J. C. 4th.Southgate W. M. Purohit D. M.  2002 . Evaluation of the i-STAT Portable Clinical Analyzer for point-of-care blood testing in the intensive care units of a university children’s
hospital . Ann. Clin. Lab. Sci. 32 : 231 –243 . 12175085 
21 Randremanana R. V. Razafindratsimandresy R. Andriatahina T. Randriamanantena A. Ravelomanana L. Randrianirina F. Richard V.  2016 . Etiologies, risk factors and impact of severe diarrhea in the under-fives in Moramanga and Antananarivo, Madagascar .
PLoS One 11 : e0158862 . doi: 10.1371/journal.pone.0158862 27411101 
22 Reece W. O.  1980 . Acid-base balance and selected hematologic, electrolyte, and blood chemical variables in calves: milk-fed vs conventionally
fed . Am. J. Vet. Res. 41 : 109 –113 . 7362116 
23 Schroeder D. G. Brown K. H.  1994 . Nutritional status as a predictor of child survival: summarizing the association and quantifying its global impact .
Bull. World Health Organ. 72 : 569 –579 . 7923536 
24 Smith G. W.  2009 . Treatment of calf diarrhea: oral fluid therapy . Vet. Clin. North Am. Food Anim.
Pract. 25 : 55 –72, vi . doi: 10.1016/j.cvfa.2008.10.006 19174283 
25 Talbert A. Thuo N. Karisa J. Chesaro C. Ohuma E. Ignas J. Berkley J. A. Toromo C. Atkinson S. Maitland K.  2012 . Diarrhoea complicating severe acute malnutrition in Kenyan children: a prospective descriptive study of risk factors and
outcome . PLoS One 7 : e38321 . doi: 10.1371/journal.pone.0038321 22675542 
26 Tennant B. Harrold D. Reina-Guerra M.  1968 . Hypoglycemia in neonatal calves associated with acute diarrhea . Cornell
Vet. 58 : 136 –146 . 5655836 
27 Tette E. M. Neizer M. Nyarko M. Y. Sifah E. K. Nartey E. T. Donkor E. S.  2016 . Changing patterns of disease and mortality at the children’s hospital, accra: are infections rising? PLoS
One 11 : e0150387 . doi: 10.1371/journal.pone.0150387 27045667 
28 Tette E. M. A. Nyarko M. Y. Nartey E. T. Neizer M. L. Egbefome A. Akosa F. Biritwum R. B.  2016 . Under-five mortality pattern and associated risk factors: a case-control study at the Princess Marie Louise Children’s Hospital in Accra,
Ghana . BMC Pediatr. 16 : 148 . doi: 10.1186/s12887-016-0682-y 27581079 
29 Trefz F. M. Feist M. Lorenz I.  2016 . Hypoglycaemia in hospitalised neonatal calves: Prevalence, associated conditions and impact on prognosis .
Vet. J. 217 : 103 –108 . doi: 10.1016/j.tvjl.2016.10.001 27810199 
30 Trefz F. M. Lorenz I. Lorch A. Constable P. D.  2017 . Clinical signs, profound acidemia, hypoglycemia, and hypernatremia are predictive of mortality in 1,400 critically ill neonatal calves with
diarrhea . PLoS One 12 : e0182938 . doi: 10.1371/journal.pone.0182938 28817693 
31 Tsukano K. Inoue H. Suzuki K.  2017 . Increase in branched-chain amino acids due to acidemia in neonatal calves with diarrhoea . Vet. Rec.
Open 4 : e000234 . doi: 10.1136/vetreco-2017-000234 29177054 
32 World Health Organization. 1999 . Management of Severe Malnutrition: a Manual for Physicians and Other Senior Health
Workers, World Health Organization, Geneva.
33 Youanes Y. D. Herdt T. H.  1987 . Changes in small intestinal morphology and flora associated with decreased energy digestibility in calves with naturally occurring
diarrhea . Am. J. Vet. Res. 48 : 719 –725 . 3592372