Bull Vet Inst Pulawy 51, 83-87, 2007
RELATIONSHIP BETWEEN THE DEGREE
OF DEHYDRATION AND THE BALANCE
OF ACID-BASED CHANGES IN DEHYDRATED CALVES
WITH DIARRHOEA
HASAN GUZELBEKTES, ALPARSLAN COSKUN, AND ISMAIL SEN
Department of Internal Medicine, Faculty of Veterinary Medicine,
Selcuk University, 42075, Campus, Konya, Turkey
[email protected]
Received for publication May 20, 2006.
Abstract
The aim of the study was to investigate acid-base
changes and to determine some serum biochemical parameters
in dehydrated calves with diarrhoea according to the degree of
dehydratation. Thirty diarrhoeic dehydrated calves submitted
to treatment in the university clinic, were used in the study.
The calves were accessed as suitable for this study, if they
were moderately or severely dehydrated according to clinical
symptoms. All sick calves had the usual yellow and watery
diarrhoea. Calves with 4% to 8% dehydration (moderate) had a
weak suckle reflex, dry mucous membranes, warm mouth and
partly good muscular tone. Calves with 10% and above
dehydration (severe) were unable to stand, and had no suckling
reflex and cold mouth. The mean pH, base excess, HCO3¯,
chloride (only severely dehydrated group) and sodium were
significantly decreased in both moderately and severely
dehydrated groups. On the other hand, potassium, phosphorus,
and anion gap levels were increased, compared to that of the
control group. Results of this study showed that there was a
relationship between the base excess and anion gap, with a
degree of clinical dehydration. However, there may not be an
exact correlation between the degree of dehydration and the
severity of acidosis. Based on the clinical symptoms, the
results of this study could be a useful tool under field
conditions, in estimating the base excess in diarrhoeic
dehydrated calves, when acidosis therapy is needed.
Key words: calves, diarrhoea, dehydration,
acid base balance.
The diseases that accounts for most calf
illnesses and deaths are septicaemia, diarrhoea and
pneumonia (1, 2). Neonatal diarrhoea is a major source
of economic loss in the cattle industry, and a leading
case of calf mortality in most countries (23). Financial
losses arise not only from mortality, but also from the
cost of medication and labour needed to treat sick
calves. Diarrhoea can lead to dehydration, acidaemia,
primarily due to strong ion (metabolic) acidosis,
hyperkalaemia, and impaired cardiovascular and renal
functions (7, 19).
L-lactic acidosis is thought to arise from poor
tissue perfusion, due to dehydration or endotoxaemia
with subsequent anaerobic glycolysis and decreased
hepatic clearance of L-lactate (21). Formation of Llactate from anaerobic glycolysis following tissue
hypoperfusion has long been considered to be a cause of
high anion gap acidosis in calves with neonatal
diarrhoea. A clinically important problem is the
identification of plasma strong anions (such as lactate, βhydroxybutyrate, acetoacetate, sulphate, and anions
associated with uraemia) that are not routinely measured
(17). Measurement of these strong anions, often results
in a new test for a clinical laboratory, requiring
additional equipment or special handling of blood
samples to ensure that changes in strong anion
concentrations do not occur after blood collection. For
this reason, many strong anion concentrations are not
routinely determined (9, 10). However, these
unmeasured strong anions traditionally have been
quantified by calculating the anion gap (11).
Electrolyte imbalance and acidosis have been
considered as the major systemic changes in diarrhoeic
calves, and often result in the death of calves in the
absence of corrective measures (22). Altered hydration
status (usually dehydration) can be estimated and
quantified by accessing the eye position within the orbit,
extent of skin elasticity, and the degree of mucous
membrane moistness (8). Therapeutic studies report that
the correction of acidosis is essential to the well being of
calves with diarrhoea (4, 14). Furthermore, preventing
the development of acidosis has long-term benefits on
the demeanour and survival of diarrhoeic calves (20).
The measurements of the buffer needs, are based on
formulas for extracellular base excess (from blood gas
analysis), or plasma TCO2 concentrations (3, 24).
However, the measurement of blood gas analysis or
plasma TCO2 concentrations is very difficult under field
conditions.
84
The aim of the study reported here was to
investigate the acid-base changes, and to determine
some serum biochemical parameters in dehydrated
calves with diarrhoea, according to dehydration degree.
Material and Methods
Animals. Thirty diarrhoeic dehydrated calves
(up to the age of 45 d) submitted to treatment at the
university clinic were used in the study. The majority of
the calves were Swiss–Holstein breed. The routine
clinical examinations of all the calves following
submission were performed. The calves were considered
suitable for this study if they were moderately or
severely dehydrated. Dehydration degree was scored
according to Constable et al. (8), and the calves were
divided into two groups according to the degree of
dehydration (Table 1). Calves with shock or mild
dehydratation were not included in the study.
Ten healthy calves (group I) (up to the age of
60 d) located in a dairy farm were used as controls. Two
calves in group II and 3 calves in group III had suffered
both respiratory disease and diarrhoea. All sick calves
were treated with antibiotics, oxygen therapy (if
needed), and fluid infusion (oral/intravenous).
Collection of blood samples. Blood samples
were taken from the jugular vein immediately following
submission of the calves. An aliquot of blood was
placed into EDTA-containing plastic tube for
haematocytometry, and another aliquot of blood was
placed into a heperanized plastic tube for blood gas
analysis. The rest of the blood sample was placed into
glass tubes for serum. These tubes were centrifuged and
the serum was harvested, and immediately frozen at –
20οC until analysis.
Blood analysis. A complete blood count (CBC)
was performed by Medonic CA 530 Thor. Blood gas
analysis (pH, PO2, PCO2, HCO3, base excess) was made
using the GemStar auto analysis (GEM Premier Plus).
The total Serum protein (TP), globulin, albumin and
phosphorus,
chloride,
potassium,
and
urea
concentrations were measured by spectrophotometer.
Determination of anion gap (AG). The AG
was calculated using the following formula:
AG: [Na+ ]+[K+]-[HCO3-]+[Cl-]
Statistical analysis. ANOVA and Duncan’s
multiple range tests were used to evaluate differences
among groups and significance levels of variation (SPSS
10.0 for Windows).
Results
All sick calves had the usual yellow and watery
diarrhoea. According to history taken from the owners,
the calves were affected by diarrhoea for about 1 to 3 d.
Calves with 4% to 8% dehydration (group II) had a
weak suckle reflex, dry mucous membranes, warm
mouth, and partly good muscular tone, in addition to the
other general clinical symptoms described in Table 1.
Calves with 10% and in above dehydration (group III),
were unable to stand, and had no sucking reflex, and
cold mouth, in addition to the other general clinical
symptoms described in Table 1.
The heart rate in four calves with 10% and
above dehydration was increased, compared to that of
normal values. In addition, the quality of their peripheral
pulse was not good.
Haematological
values,
some
serum
parameters, and acid-base changes in both healthy and
dehydrated calves are presented in Tables 2 and 3. The
results of blood gas analyses of group II and III, were
compared with the healthy group (group I): pH, HCO3,¯
chloride (only group III), and the sodium was
significantly decreased, while potassium, phosphorus,
and anion gap levels were increased. Anion gap,
potassium, and base excess increased in the calves of
group III as compared with the calves of group II, but
chloride and HCO3¯ concentrations were decreased.
WBC counts, and HCT in calves of groups II
and III were increased significantly, compared with the
control group. Serum phosphorus and urea levels in the
calves of groups II and III were higher than those in
calves of control group. However, levels of these
parameters were much higher in group III in comparison
to group II. While serum albumin concentrations in
group III compared to group I were high, serum globulin
levels were found to be low. Serum calcium level was
within the normal range. The mean serum glucose levels
in groups II and III were increased when compared to
the healthy group.
Discussion
Dehydration and disturbances in electrolyte
balance in diarrhoeic neonatal calves cause various
clinical symptoms, and even death in some cases (6, 18).
The severity of metabolic acidosis and changes in some
serum parameters in diarrhoeic dehydrated calves
included in this study, were observed according to the
degree of dehydratation.
Metabolic acidosis in diarrhoeic calves was
originally attributed to faecal bicarbonate loss, as well as
the presence of unidentified organic acids in plasma, and
a decrease in glomerular filtration rate in response to
severe dehydration (7). Kasari (15) reported that pH
values below 7.28 and HCO3¯ concentration of 20.0
mmol/L, are reflective of metabolic acidosis in a
neonatal calf. The mean base excess –9.6 mEq/L, mean
pCO2 43 mmHg, mean pO2 39 mmHg, and mean pH
7.21 in calves with 4% to 8% dehydration were found in
this study. These calves had a moderately severe
metabolic acidosis with respiratory compensation;
however, the mean anion gap was increased up to 20.34
mEq/L in calves with 4% to 8% dehydration. The
traditional (Henderson-Hasselbach) approach to an acid–
based balance, has usually involved the calculation of
the anion gap in order to quantify the unmeasured anion
concentration (9).
85
Table 1
The evaluation of hydration status in dehydrated calves with diarrhoea
Dehydration (%)
4-8
(group II)
10 and over
(group III)
Clinical signs
Enophthalmos; 2 - 4 mm
Decreased cervical skin elasticity–tent duration 4 - 6 s
Cool extremities
Able to stand but with difficulty
Enophthalmos; 6 mm and over
Decreased cervical skin elasticity –tent duration; 7 s and above
Cold extremities
White mucous membranes
Recumbent and unable to stand
Table 2
Haematological values and some serum biochemical parameters (mean ± SEM)
in dehydrated diarrhoeic and healthy calves
Dehydrated diarrhoeic calves
Control
4% to 8%
10% and over
(n = 10)
(n = 15)
(n = 15)
RBC
106/mm3
6.10 ± 0.26
6.83 ± 0.49
6.99 ± 0.44
WBC 103/mm3
10.18 ± 0.51 a
14.85 ± 1.71 ab
19.92 ± 2.28 b
HGB
g/dL
10.32 ± 0.51
10.46 ± 0.41
10.06 ± 0.56
HCT
%
27.20 ± 0.87 a
31.51 ± 1.55 b
37.34 ± 1.10 c
Glucose mg/dL
70.80 ± 3.29 a
82.93 ± 3.29 b
91.07 ± 6.36 b
a
b
Urea
mg/dL
13.70 ± 0.99
32.50 ± 4.66
49.00 ± 9.12 b
Protein g/dL
5.95 ± 0.15
6.20 ± 0.21
6.39 ± 0.34
Albumin g/dL
3.03 ± 0.27 a
3.74 ± 0.33 ab
4.40 ± 0.46 b
Globulin g/dL
2.92 ± 0.28 a
2.51 ± 0.16 ab
2.07 ± 0.17 b
I. Ca
mg/dL
0.95 ± 0.05
0.94 ± 0.06
0.85 ± 0.07
7.54 ± 0.66 a
11.01 ± 1.42 b
P
mg/dL
6.64 ± 0.35 a
abc
Different letters in the column indicate the significant differences ( P< 0.05).
Parameters
Table 3
Results of blood gas analyses (mean ± SEM) in dehydrated diarrhoeic and healthy calves
Dehydrated diarrhoeic calves
Control
4% to 8%
10% and over
(n = 10)
(n = 15)
(n = 15)
pH
7.38 ± 0.01 a
7.21 ± 0.06 b
7.13 ± 0.04 b
pCO2
mmHg
47.10 ± 1.29
43.00 ± 3.12
41.36 ± 1.85
pO2
mmHg
40.20 ± 1.25
39.43 ± 1.57
40.71 ± 1.59
Na
mmol/L
141.30 ± 1.00 a
133.86 ± 2.56 b
134.29 ± 1.97 b
K
mmol/L
4.02 ± 0.11 a
4.63 ± 0.15 b
5.36 ± 0.35 b
HCO3
mmol/L
26.55 ± 0.70 a
15.01 ± 2.18 b
12.21 ± 1.15 b
Base excess mmol/L
3.06 1.01 a
-8.66 ± 3.95 b
-17.81 ± 1.46 c
a
a
Chloride mmol/L
104.10 ± 1.22
107.50 ± 3.02
94.43 ± 3.35 b
a
b
Anion gap mmol/L
10.89 ± 1.29
20.34 ± 1.31
34.83 ± 2.98 c
abc
Different letters in the column indicate the significant differences ( P< 0.05).
Parameters
86
Lorenz (16) found that there was no significant
correlation between the base excess and degree of
dehydration as assessed by the urea concentration.
However, Stocker et al. (25) reported that in the calves
that were unable to stand up, the acidosis was
significantly more severe than in the calves that could
stand up. The mean base excess –17.8, mean pCO2 41
mmHg, mean pO2 40 mmHg, and mean pH 7.13 in
calves with 10% and above levels of dehydration were
determined in this study. These calves had a severely
metabolic acidosis with respiratory compensation, and
the mean anion gap levels were increased up to 34.83
mEq/L. However, there were no exact correlations
between the base excess and clinical pictures of some
calves (total of 7 calves) in both groups. But, anion gap
levels in calves with 10% and above levels of
dehydration were higher than those of calves with 4% to
8% dehydration. It could be said that there was a
relationship between anion gap and the degree of
dehydration. If calves with high levels of anion gap
recover following treatment, the high anion gap might
be a minor impact on disease prognosis. Omole et al.
(21) found that the concentrations of all acids measured
(pyruvic, lactic, and acetic) were significantly higher in
diarrhoeic calves. This indicates that all acids contribute
to a lower mean pH value, and higher anion gap in
diarrhoeic calves (9, 10).
Important risk factors for the development of
septicaemia in calves include decreased passive transfer
of colostral immunoglobulins, and exposure to invasive
bacterial serotypes (5,12). High WBC counts and
decreased serum globulin concentrations in groups II
and III were observed in this study. Total serum protein
concentration levels of less than 5.0 g/dL are a cause for
concern; greater than 5.0 g/dL may be partially or
completely protective in the normally hydrated calf that
is only a few days old (13). Turgut et al. (26) reported
that serum total protein concentrations, could not be an
accurate diagnostic index in the determination for the
failure of passive colostral transfer. Serum urea, total
protein concentration, and HCT are increased in groups
II and III compared to the healthy group. Increase in
serum TP could be the results of dehydration, not
immunity. Azotaemia may also be related to a decrease
in glomerular filtration rates, in response to severe
dehydration.
Dehydrated neonatal ruminants typically have a
hyponatraemic, hyperkalaemic, and metabolic acidosis
(10). The total body potassium content is decreased in
diarrhoea (23). A study of a large number of calves with
naturally acquired diarrhoea, showed no correlation
between heart rate and blood potassium concentrations,
although another study found that the heart rate
increased linearly with serum potassium concentrations
up to K+ = 8mEg/L.
Bradycardia, defined as less than 90 beats per
minute, is seen in hypothermia, hypoglycaemia, and
hyperkalaemia.
Although
serum
potassium
concentrations in calves of group III was high and
statistically important, bradycardia was not noted by
auscultation, because the mean potassium levels were
close to normal range of the values. The mean decreased
serum sodium concentrations, and increased serum
phosphorus levels in groups II and III may be also
related to dehydration.
In conclusion, the results reported here,
identifies that there was relationship between the base
excess and anion gap with a degree of clinical
dehydration. In addition to this, serum urea had
increased according to the degree of dehydration.
However, there may not be an exact correlation between
the degree of dehydration and the severity of acidosis.
Based on the clinical symptoms, the results of this study
could be a useful tool under field conditions, in
estimating the base excess in diarrhoeic dehydrated
calves when acidosis therapy is needed.
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