incidencia por idade e Diagnosis of neonatal calf diarrhoea Millemann 2009 RMV

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Revue Méd. Vét., 2009, 160, 8-9, 404-409
Introduction
Diarrhoea is characterized by the more frequent production
of faeces that are wet and soft (less than 10% dry content).
This clinical sign is easy to diagnose but non specific.
Effectively, it is encountered in a number of diseases of the
young animal, which are due to several agents: these agents
can act concomitantly to produce the disease in the calf. 
Often, this group of diseases is named “enteritis”, although
classical inflammation of the mucosa may not be present.
For instance, when diarrhoea is associated with enterotoxi-
genic strains of E. coli, there is mainly a large net increase of
secretion due to enterotoxins, with minor lesions of the gut
mucosa.
Diarrhoea is the most important disease of neonatal calves
and results in the greatest economic loss due to disease in
this age group in both dairy and beef calves. Outbreaks of
neonatal calf diarrhoea (NCD) can be indeed costly, espe-
cially for beef producers, as treatment of affected calves is
time consuming, and the death of a calf represents the loss of
profit from that cow–calf unit for the year. Additionally for
survivors there may be impacts on subsequent calf growth
rate and weaning weight, loss of genetic potential and a
decreased capacity to improve and maintain the herd. 
NCD is generally observed together with other clinical
signs, among them essentially dehydration with acid-base
imbalance. Dysentery or even abdominal pain (colic) can be
seen. All this depends on the cause of diarrhoea, on the
pathogenesis (enteritis, malabsorption…), on the location
and severity of corresponding lesions… 
At the individual level, the precise diagnosis is not always
indispensable, because it does not affect the course of actions
to take (generally urgent rehydration followed by a number
of hygienic measures and supportive treatment).
But at the herd level, diagnosis is important, and it has
consequences in question of applied treatment or vaccination.
Aetiological diagnosis of calf scours has to be made as rapidly
as possible. Effectively, as infectious agents are generally
implicated, it is of importance to check what agent(s) is (are)
circulating in the herd and is/are mainly determining the obs-
erved outbreak. An adapted treatment may be proposed after
diagnosis and above all the diagnosis may help defining an
adapted prophylaxis based on vaccination of dams or calves
as well as modification of management of the herd in the
areas of feeding, control of parasitism, etc. 
Finally it is also of importance to check whether the outbreak
is due to a zoonotic pathogen such as Salmonella,
Campylobacter…
SUMMARY
Neonatal calf diarrhoea (NCD) is the most important disease of neonatal
calves and results in the greatest economic losses due to disease in this age
group in both dairy and beef calves. NCD outbreak associated costs include
treatment time, possible impact on subsequent calf growth performances
and potential death. NCD results from a combination of an adverse envi-
ronment, poor host immunity and challenge from infectious agents. While
an etiological diagnosis in NCD cases may not be relevant for the treatment
of the individual, such diagnosis helps determining which adapted measures
can be taken on herd level especially if zoonotic pathogens are involved.
The clinical diagnosis should be based on the clinical picture including the
age of the affected animals and associated clinical signs collated through a
thorough physical examination together with epidemiological data inclu-
ding the season and herd history. In most situations, the clinical diagnosis
requires confirmation by on-farm or laboratory tests.
Keywords: Calf, diarrhoea, diagnosis, herd, epidemiology,
clinical signs, confirmation, laboratory.
RÉSUMÉ
Diagnostic des diarrhées néonatales du veau
Les diarrhées néonatales du veau constituent la maladie la plus importante
des veaux nouveau-nés, entraînant les pertes économiques les plus élevées
dans cette classe d’âge, tant chez les veaux laitiers que chez les veaux allai-
tants. Les coûts associés aux diarrhées néonatales du veau comprennent le
temps dévolu au traitement, l’impact possible sur les performances de crois-
sance du veau et la mortalité. Les diarrhées néonatales du veau résultent de
la combinaison de facteurs environnementaux défavorables, d’une immunité
faible de l’hôte et d’agents infectieux. Alors qu’un diagnostic étiologique
des cas de diarrhées néonatales se révèle peu important sur le plan du trai-
tement individuel, en revanche il aide à déterminer quelles sont les mesures
adaptées à prendre au niveau du troupeau, surtout si des agents zoonotiques
sont impliqués. Le diagnostic clinique devrait être fondé sur les données cli-
niques, comprenant l’âge des animaux atteints et les symptômes associés
relevés grâce à un examen clinique consciencieux, ainsi que des données
épidémiologiques incluant la saison, et l’historique du troupeau. Dans la
plupart des situations, le diagnostic clinique requiert une confirmation par
des tests réalisables dans la ferme ou avec l’aide du laboratoire.
Mots clés : Veau, diarrhée, diagnostic, troupeau, épidé-
miologie, signes cliniques, confirmation, laboratoire.
Diagnosis of neonatal calf diarrhoea
Y. MILLEMANN*
Pathologie du Bétail, Ecole Nationale Vétérinaire d’Alfort, 7 avenue du général de Gaulle, 94704 Maisons-Alfort cedex, FRANCE.
*Corresponding author: ymillemann@vet-alfort.fr
Cet article a fait l’objet d’une communication au 4ème “Dairy Solutions Symposium” les 25 et 26 septembre 2008, Lasalle Beauvais, FRANCE.
Revue Méd. Vét., 2009, 160, 8-9, 404-409
DIAGNOSIS OF NEONATAL CALF DIARRHOEA 405
Therefore, in order to adapt therapeutics and prophylactic
advices, it is of importance to search for the precise aetiology
of the observed digestive disorders.
Epidemiology 
Neonatal calf diarrhoea (NCD) occurs mainly in calves
less than six weeks of age, although calves up to four months
of age may be affected. It can affect beef as well as dairy cal-
ves. It occurs mainly also during the winter period and when
animals are within stables [5]. Lots of animals can be affec-
ted: for instance, in a French study on beef calves, the mean
incidence rate for diarrhoea during the neonatal period was
14.6%, with herds having an incidence over 50% [2]. 
During the winter season, the number of diarrhoeic calves
increases often together with the severity of the disease. This
is linked to the fact that the infection pressure for neonates
tends to increase progressively. A number of key points can
explain this phenomenon. First, all major enteric pathogens
are commonly carried by asymptomatic adult cows and
shedding of many pathogens species tends to increase
around calving. Second, healthy calves are often asympto-
matically or subclinically infected with enteric pathogens
and amplify environmental contamination. Finally, all major
enteric pathogens can survive in the environment and water
sources for weeks to months (and in most cases over a year)
in cool, damp conditions.
Many other animals, including feral animals and domestic
pets, can also contribute to the contamination of calves by
pathogens like Cryptosporidium, Salmonella or rotavirus.
Because of its essential infectious aetiology, NCD incidence
increases in herds where infection pressure increases and in
herds where calves have an inadequate immunity: this can be
due to a failure of transfer of colostral immunity or to stres-
sing factors like a cold weather [1, 16].
Aetiology
NCD is a multifactorial disease and results from a combi-
nation of an adverse environment, poor host immunity and
challenge from infectious agents [1, 16]. Although a very
serious impairment in any one of these factors can lead to
disease, NCD outbreaks usually reflect a problem in all three
areas. Consequently it is importantto address the problem at
a herd level by assessing risk factors and implementing pre-
ventive management.
ADVERSE ENVIRONMENT
Adverse conditions in the environment of the neonate can
contribute to the emergence of diarrheal outbreaks. For
instance, a cold winter with air drafts falling on calves, a wet
litter, a litter made of granite fines are risk factors associated
with NCD [15]. Indeed, environment of neonates is a key
factor in the emergence of diarrhoea: housing with abundant
straw bedding, nature of the pen walls, air volume per animal
[12]… Also, the absence of cohabitation with animals of
other age classes is important to control. 
One must not forget that diarrhoea may have also a nutri-
tional origin. This can be linked to the distribution of raw
milk at unsuitable temperatures, or of too large quantities
(over 3 L per meal). This can be linked also to the use of milk
replacers of inferior quality, or badly prepared (with
lumps…). All this can lead to the appearance of diarrhoea in
the calves, with often great quantities of soft faeces. But,
initially, there is no or minimal systemic effect… until there
is superinfection by a pathogen.
POOR HOST IMMUNITY 
A poor immunity in neonatal calves is essentially linked to
a failure of passive transfer (FPT) of colostral antibodies.
This may be due to an insufficient or delayed ingestion of
colostrum by the neonate or to a poor quality of the colos-
trum [11, 13-14]. Adequate ingestion of the colostrum by the
neonate can be easily controlled by a careful farmer. Colos-
trum quality can be checked with a colostrometer; this quality
is conditioned by the parity and the sanitary status of the dam,
linked to the control of parasitism, the nutrition, the season [9]… 
CHALLENGE FROM INFECTIOUS AGENTS 
Several pathogenic agents can, alone or, most often, in
combination, determine diarrhoea in the young calf. These
agents can also act successively in the same calf: this can
explain discrepant laboratory results of successive analyses
for a single calf or between calves in the same herd.
Enteropathogenic agents are usually present in the environ-
ment of the calves or are carried and shed by the dam or
other animals from the herd: sick or convalescent animals,
asymptomatic carriers [5, 18]… During calving season, the
concentration of pathogens in the environment increases pro-
gressively, with an amplification by the first calves of the
season. This increases infectious pressure, and, associated
with favourable conditions, this leads to a degradation of the
health of calves and to the emergence of real neonatal diar-
rhoea epizootics.
The main agents responsible for diarrhoea in the calf [16]
(Table I) are bacteria (mainly Escherichia coli strains, Table
II), parasites (essentially Cryptosporidia) and finally viruses
(among them particularly rotaviruses and to a less extent
coronaviruses). 
Enteropathogenic agents are very frequently isolated from
faeces of diarrhoeic calves that were not preliminarily trea-
ted with antibiotics, E. coli being the commonest. E. coli is
isolated alone in half of the cases but a sequential action of
several agents can not be excluded. In other cases, E. coli is
isolated along with other agents: most often associated
pathogens are by decreasing importance cryptosporidia, rota-
viruses, coronaviruses, and toroviruses [5, 6, 10].
Finally an essential point must be underlined: whatever the
responsible pathogen(s), diarrhoea is frequently associated in
Revue Méd. Vét., 2009, 160, 8-9, 404-409
406 MILLEMANN (Y.)
the young calf (from the birth to 3-4 weeks of age) to a
toxaemia and/or a septicaemia that complicate the disease
and worsen the prognosis.
Clinical diagnosis 
Practical diagnosis will first rest on the thorough clinical
examination of affected calves, together with a precise
anamnesis.
The aspect of diarrhoea can help orientating the diagnosis,
which will be based on associated signs as well as the age of
the affected animals (Table III). Effectively, each neonatal
disease characterised by diarrhoea in the calf has its peak
incidence at a specific age (Figure 1). Colibacillosis is generally
Bacteria Viruses Parasites 
E. coli : ETEC, EPEC, EHEC Rotavirus Cryptosporidium
Salmonella Coronavirus Giardia
Clostridium Torovirus (Breda) Eimeria bovis, or zuernii (animals over 3 weeks)
Campylobacter BVDV/MDV Candida 
Calicivirus (norovirus)… Toxocara
Strongyloides
TABLE I: Main pathogenic agents responsible for diarrhoea in the calf (non exhaustive list).
Bold characters underline the most often encountered pathogens.
Pathotype ETEC (entero-toxigenic E. coli) VTEC (vero-toxigenic E. coli)a EPEC (entero-pathogenic E. coli)b
Age of affected calves < 5 days 1 to 3 weeks 1 to 3 weeks
Adhesins K99 (F5), F41, FY Intimin (Eae) BFP (“bundle forming pili”)
(+/- CS31A) Intimin (Eae)
Toxins STa (ST1) VT1 and VT2 (Stx1, Stx2) -
TABLE II: Main Escherichia coli pathotypes responsible for calf diarrhoea and associated virulence factors [17, 23].
a mainly EHEC: enterohaemorrhagic E. coli; can be named STEC (shigatoxic E. coli). Responsible for HUS (haemolyitic and uremic syndrome) in the child
under 5 years, mainly serotype O157:H7.
b mainly AEEC: adhering-effacing E. coli.
Mean age of affected calves Clinical signs Probable aetiological diagnosis 
1-3 days Very liquid diarrhoea, yellow Colibacillosis (ETEC = F5 E. coli)
Rapid and important dehydration (eyes
sunkness, diminished skin elasticity)
Weakness, cold extremities
4-11 days Mucoid diarrhoea Rotavirosis, coronavirosis, cryptosporidiosis
Hyperthermia
Anorexia, abdominal pain
Progressive dehydration
> 11 days Very liquid diarrhoea with blood traces Salmonellosis 
Severe hyperthermia (> 41°C)
> 18 days Black diarrhoea, +/- blood and colic Coccidiosis due to Eimeria zuernii
Mucoid diarrhoea, hyperthermia Bovine viral diarrhoea
Ptyalism, anorexia, epiphora
TABLE III: Helpful elements for the differential diagnosis of NCD.
FIGURE 1: Incidence of the causes of diarrhoea according to the age of
calves (adapted from [18]).
Revue Méd. Vét., 2009, 160, 8-9, 404-409
DIAGNOSIS OF NEONATAL CALF DIARRHOEA 407
encountered in very young calves (under 5 days) while coc-
cidiosis (eimeriosis) will affect preferentially calves over 3
weeks.
Because of the pathogenic course of diarrhoea, the affected
animal will generally experience dehydration together with a
more or less severe acidosis linked to either faecal losses of
bicarbonate or L-lactate production following dehydration or
D-lactate production by Lactobacilli. The age of the calf
plays a great role in the susceptibility of the calf to the diar-
rhoea. Dehydration and acidosis (especially D-lactic acidosis
occurring in the “diarrhea without dehydration syndrome” in
10-day-old calves) have systemic consequences and lead to
depression, recumbency, or even cardiac or renal failure…
Hypothermia or cachexy may also been observed in affected
calves.
Together with the age of the affected calf, the observed
systemic effects and their severity can orientate the practitio-
ner towards the suspected responsible enteropathogen. For
instance, a marked hyperthermia (> 40.5-41°C) may lead to
a suspicion of colibacillosis, salmonellosis or coronavirosis,
as well as a high mortality of affected calves. By contrast, a
low mortality is rather evocative of rotavirosis. We may note
also that the absence or presence of hyperthermia in the
affected calf determines the choice for the adapted treatment,
taking into account the responsible and prudent use of anti-
biotics [4]. 
When NCD is accompanied by mortality, the practitioner can
obtain interesting hints by realising a necropsic examination:
observed lesions and samples can be very helpful to determine
the aetiological agent. Necropsy will also aid evidencing the
possible implication of thesuspected pathogen in the diarrheal
episode: one must keep in mind that the presence of an ente-
ropathogen in an affected calf is not enough to prove its role in
the pathogenic process. Indeed, asymptomatic carriers and shed-
ders exist, and the evidence of associated lesions is necessary
to demonstrate the implication of a suspected pathogen.
Paraclinical diagnosis 
The clinical examination in the farm leads to a suspicion
towards the implicated pathogen, together with a number of
risk factors contributing to the outbreak. The practitioner
needs afterwards to confirm his suspicion with the help of
laboratory tests (Table IV). Among them, several can be carried
out by the practitioner in the field or in his clinic (Table V). 
Moreover, when faced to an outbreak of NCD in a herd
one must verify FPT by measuring gamma-globulinemia in
calves [13, 14, 20, 22]. A number of dedicated commercial
tests that can be carried out in the field is today available
(Table V, first lines). Once the FPT is diagnosed, the practi-
tioner will help improving the passive transfer of immuno-
globulins in calves [7, 8].
Agent Sample Carried out method - observations
E. coli Faeces, intestinal content Elisa « BVT »
Culture then slide agglutination (F5, F41, F17, CS31A) 
Antibiotic resistance profile.
Search for genes specific for septicaemic E. coli [19]
Salmonella Faeces; on dead animal: ileo-colon, Culture, then antibiotic resistance profiling and serotyping
mesenteric lymphatic nodes, spleen, Serology: no diagnostic interest 
liver (aborted foetus)
Clostridium Faeces, intestinal content (hermetically sealed Culture and enumeration 
flacon), 4°C, brief delay for analysis Possible search for genes coding for toxins (PCR) 
Do not forget C. difficile ? [21]
Rotavirus Faeces; on dead animal: ileon Elisa « BVT »
Immuno-enzymatic search, latex test
Pb: only group A rotaviruses 
Coronavirus Faeces; on dead animal: ileo-colon Elisa « BVT »
Immuno-enzymatic search, agar immuno-diffusion 
Sensitivity 106 PFU /g
Adénovirus  Faeces Human ELISA kits useful [3]
Calicivirus  Faeces RT-PCR for identification [24] based on group primers 
Human ELISA kit useful because of the antigenic community.
Torovirus  Faeces ELISA and RT-PCR have been described [10].
Possible development of a multiplex RT PCR for cattle: 
calicivirus and adenovirus (+ astrovirus)
Pestivirus BVD/MD Faeces: NO! Immuno-enzymatic test in 24h (Antigen), cellular culture
Naso-pharyngeal lavage, blood (PI only); on (gold standard: 8-21d), immunofluorescence on organs
dead animal: ileo-colon, lymphatic nodes, (1-3d delay)
spleen, abomasum, rectum, lung (aborted foetus)
Cryptosporidium Faeces Microscopic examination (Ziehl Neelsen, Heine…)
Eimeria (bovis, zuernii) Faeces Microscopic examination
TABLE IV: Samples to be done according to the suspected enteropathogen in face of calf diarrhoea.
Revue Méd. Vét., 2009, 160, 8-9, 404-409
408 MILLEMANN (Y.)
Conclusion
In conclusion, NCD remains the most important disease in
calves under 4 weeks, responsible for huge economical losses.
Several enteropathogens can act successively or together to
determine NCD in herds where risk factors are present,
which impair the calf’s immunity and especially contribute
to FPT. 
Although NCD is quite easy to identify, a precise aetiolo-
gical diagnosis is difficult to carry out. It is indispensable in
herds where the infection pressure increases, to adapt the
treatment but also and above all the preventive measures. It
is also useful when the suspected agent is of public health
concern.
In order to carry out a precise diagnosis, the practitioner
needs first to carry out thoroughly a clinical examination of
the affected animals: the age of affected calves, together with
the aspect of the faeces and the associated clinical signs help
to hypothesize what is the probable diagnosis. Afterwards,
with the help of rapid tests that can be carried out in the farm
or in the clinic, or even with the help of laboratory analyses
or a precise necropsy, the diagnosis can be confirmed.
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Bovine® IgG (Midland) Colostrum Immunochromatography 20 minutes
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Calf® IgG (Midland) Total blood Evidence of a quantitative failure of IgG in the calf’s blood 20 minutes
Speed® Giardia Faeces Immunochromatography 5 minutes
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DIAGNOSIS OF NEONATAL CALF DIARRHOEA 409
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