Diarrhoea or calf scour can be a major cause of poor growth and
calf mortality in many dairy herds. The incidence and severity of
disease is highly dependent upon the level of colostral protection
that a calf receives within the first six hours of life (Fig 1).
Indeed, it is generally recommended that calves receive three
litres within the first 2 hours of life. 1,2,3; first milk, within
two hours, three litres!
Fig 1: The incidence
and severity of disease is highly dependent upon the level of
colostral protection that a calf receives within the first six to
12 hours of life.
The most important causes of
calf diarrhoea are rota- and corona-viruses but on a small number
of dairy farms Salmonella species, such as Salmonella
Dublin and Salmonella typhimurium, can be a major
problem. However, it is essential to appreciate that most outbreaks
of calf diarrhoea are caused by viruses. Fluid therapy is the most
effective treatment strategy; antibiotics are rarely indicated and
their use is contrary to the responsible use of antibiotics in
As with all animal diseases
prevention is better than cure and an effective veterinary herd
health plan is essential for all dairy herds to maintain health and
prevent costly diseases. Effective vaccines are available against
the most important infectious causes of calf diarrhoea but such a
prevention strategy will only work if calves receive adequate
volumes of good quality colostrum within few hours of birth, and in
the case of viral causes, continue to receive stored colostrum from
vaccinated cows for the first two weeks of life.
Fig 2: Check for adequate colostrum ingestion if
joint infections have become a problem in young calves on your
Recent surveys have revealed
that more than two-thirds of dairy calves do not receive adequate
volumes of good quality colostrum within few hours of birth. If
calf diarrhoea, joint infections (Fig 2), meningitis (Fig 3), and
septicaemia (Fig 4) have become a problem in young calves on your
farm it would prove very worthwhile checking their immune status by
means of a simple and inexpensive blood test (measurement of total
plasma protein concentration) undertaken by your veterinary
Fig 3: Check for adequate colostrum ingestion if
meningitis has become a problem in young calves on your
Fig 4: Check for adequate colostrum ingestion if
septicaemia has become a problem in young calves on your
Delayed colostrum ingestion
may result from, recumbency of the dam caused by dystocia, trauma,
nerve damage, and milk fever (Fig 5). Unlike many beef cows, summer
mastitis should not be a problem in dairy cows but pendulous udders
and distended teats may delay sucking. Prolonged labour and nerve
damage may cause delays in the calf rising to its feet and sucking
Heifers generally produce
colostrum with 25 per cent less immunoglobulin content (protective
antibodies) than mature cows but feeding three litres should
overcome this potential problem.
Fig 5: Delayed colostrum ingestion may result from
milk fever although this calf has learned how to
The level of hygiene in most
calving boxes in seasonally-calving herds could be improved on many
farms by more regular mucking out, disinfection, and plenty of dry
barley straw bedding (Fig 6). Not only would a higher standard of
hygiene result in fewer calf diseases, it may also reduce the risks
of coliform mastitis and uterine infection in the dam. While firm
footing is important in calving boxes because of the risks
associated with cows slipping, especially when suffering from milk
fever, there is the tendency to over-compensate and not clean out
calving boxes for several weeks. Navel dressing with strong
veterinary iodine BP is essential at birth and again two to four
hours later to prevent umbilical infections.
Fig 6: Early clinical signs of
meningitis - infection acquired from dirty calving
Individual calf pens
Wet, dirty or inadequate
bedding allows a build up of pathogens in calf pens (Fig 7).
Survival of most gastrointestinal pathogens and maturation of
coccidial oocysts is best under moist, cool or warm conditions.
Some infectious agents (particularly protozoa causing coccidiosis)
survive for many months, even after routine cleaning. Poor hygiene
with respect to feeding equipment (e.g. dirty buckets and
contaminated water drinkers) constitutes an important source of
infection not only for pathogens causing diarrhoea but diseases
such as calf diphtheria.
Fig 7: Wet, dirty or
inadequate bedding allows a build up of pathogens in calf
Calf hutches provide good
accommodation with respect to the prevention of respiratory
diseases but must be cleaned out and disinfected between occupants
to prevent a build-up of enteric pathogens (see above with
reference to calf pens). Movement of calf hutches between calves is
an effective means of providing a clean surface.
Feeding artificial milk replacers
Most farmers feed artificial
milk replacers to calves from around 12 hour-old. Artificial milk
replacers prepared at the wrong temperature or concentration, and
raw milk fed at different temperatures may cause nutritional scour.
Scour in calves may also occur if animals are fed at irregular
intervals or if there is a period of enforced starvation followed
by greedy feeding. Fresh clean water must always be available
because thirsty calves (e.g. during hot weather or after transport)
may drink too much milk, resulting in nutritional scour.
Paratuberculosis can be
transmitted to newborn calves if colostrum from infected cows (Fig
8) is fed to young calves. As a general guide colostrum must only
be fed to the offspring of that cow. Pooling colostrum from
numerous cows only adds to the potential spread of
Fig 8: Paratuberculosis
can be transmitted to newborn calves if colostrum from infected
cows is fed to young calves.
Infectious causes of diarrhoea
Rotavirus infection is a
common cause of diarrhoea in young dairy calves. Calves are most
commonly affected at 8 to 14 days old when there is an acute onset
of diarrhoea with the passage of very watery yellow/green faeces.
Infection may be acquired in the calving accommodation then spread
between young calves in the calf house by direct contact. Typical
early signs include a reluctance to stand and drink, mild
depression and salivation. The calf becomes dehydrated with sunken
eyes and tight and inelastic skin; recumbency soon
The diarrhoeic calf should be
isolated in a dry, well-bedded pen. 1-2 litres of oral electrolyte
are given 4 to 8 times daily. Intravenous fluids administered by a
veterinary surgeon are essential in dehydrated calves that are
unable to stand unaided.
Oral antibiotics are not
necessary. Parenteral antibiotics should be used to control
concurrent infections, e.g. navel ill and calf diphtheria. Return
to a milk diet should be a complete change and not diluted with
electrolyte solution. Alternate milk and electrolyte solution
should be fed every four hours.
Annual vaccination of the dam
with a combined rotavirus, coronavirus and K99 combined vaccine
will prevent disease in the newborn calf following colostrum
feeding for the first two weeks of life, and is an invaluable
insurance policy in dairy herds.
Since protection of calves
depends on the physical presence of passively acquired antibodies
within the gut, calves must receive adequate colostrum from their
dams. In the dairy herd, colostrum from the first six to eight
milkings of vaccinated cows should be stored in a cool place. The
calves should then be fed on this pool at the rate of 3 to 4 litres
per day (according to body size) for at least the first two weeks
of life. Optimal results will be obtained if a whole herd cow
vaccination policy is adopted. This will ensure that the level of
infection and consequent virus excretion is kept to a minimum and
consequently, the overall level of disease challenge on the farm is
kept to a minimum.
Outbreaks of calf coronavirus
diarrhoea are similar to, or more severe than, those observed for
rotavirus infection. Fortunately, coronavirus infection is much
less common than rotavirus.
Treatment and prevention of
coronavirus infection is as outlined above for
In calves this term is used
to refer to strains of the bacterium E. coli possessing
the K99 antigen. Recent surveys show the incidence of K99 E.
coli to be very low in dairy herds. The disease
characteristically affects calves aged 1-3 days old when there is
sudden onset of profuse yellow/white diarrhoea causing rapid and
severe dehydration. The calf quickly becomes recumbent.
Accumulation of fluid in the abomasum and intestines gives the
abdomen a bloated appearance. Disease would typically follow
introduction of infection into the herd with contamination of the
calving environment and infection of newborn calves.
Enterotoxigenic E. coli infection is as outlined above for
rotavirus and coronavirus using a combined vaccine and ensuring
passive antibody transfer in colostrum.
Cryptosporidiosis is not a
major problem in dairy calves housed in individual pens but
infection can rapidly build-up in group pens fed by automatic
feeders where newborn calves are constantly added to the
Diarrhoea is caused by the
physical loss of absorptive area of the small intestine and
exacerbates the viral infections described above. There is profuse
yellow/green diarrhoea with much mucus present. There is only mild
dehydration but the calf rapidly loses condition over 2-5 days and
has a dull tucked-up appearance. Whilst morbidity is high, the
mortality rate in uncomplicated cases is usually low.
In uncomplicated cases ensure
that the scouring calf is properly hydrated and use oral
electrolyte solutions as necessary. Halofuginone lactate is
licensed for the prevention and treatment of diarrhoea caused by
C. parvum. Cryptosporidiosis is a zoonotic disease (can
affect man). Children and the elderly are most at risk when
handling calves, less so contaminated boots/clothing and other
indirect sources of infection.
Salmonella species, such as
Salmonella Dublin and Salmonella typhimurium, can
cause severe diarrhoea with the presence of blood and mucosal casts
which may result in death. More often, Salmonella infections of
young calves cause joint and bone infections and severe pneumonia
which proves very difficult to treat. Identification of Salmonella
infections necessitates detailed veterinary
Prevention and control of
calf diseases caused by certain Salmonella spp. can be achieved by
appropriate vaccination of the dam with colostral transfer of