Calf scours

Calf scours is a broad, descriptive term. It can have several causes, including non-infectious causes such as changes in feeding, or infectious causes such as viruses, bacteria and protozoa.

Scours disrupts the normal movement of water into and out of the digestive tract. This causes calves to lose water and body salts, which can lead to dehydration, severe depression in the calf and, if untreated, death.

Non-infectious diarrhoea (nutritional scours)

Commonly caused by:

Irregular milk feeding schedules e.g. amount or timing.
Poor milk quality or preparation.
Sudden dietary changes.
Stress from environmental factors.

Nutritional scours can weaken a calf and make it more susceptible to infectious diarrhoea. It is usually less severe than infectious scours and calves respond quickly to treatment.

Temperature: normal 38.5-39.5^oC

Infectious diarrhoea

Commonly caused by pathogens such as:

Rotavirus
Cryptosporidium
E. coli.
Salmonella

Calves with infectious scours can become severely dehydrated, so prompt treatment is important. Identifying the infectious agent causing diarrhoea can help to inform a prevention program.

Temperature: above 39.5^oC

The key difference

Infectious scours are almost always accompanied by other signs of illness, particularly elevated body temperature. Having a thermometer and knowing how to use it is essential for proper diagnosis.

How to take a calf's temperature in 5 steps:

Use a digital thermometer (with a flexible tip if possible).

Apply lubricant to the thermometer.

Insert gently into the rectum about 5cm deep.

Wait for the reading to stabilise.

Record the temperature along with the time and date.

Treatment of scours

Calves with scours should continue receiving milk and may need an oral electrolyte solution, depending on the severity of scours.

It is helpful to have a treatment protocol documented so all staff know how to respond to scours. Key points to consider include:

Isolate sick calves in a designated sick bay immediately.
Consult your vet for support with infectious scours.
Treat scours using oral electrolytes and continue milk feeding.
Calves with a high temperature can benefit from pain relief as it can reduce inflammation and improve suckling behaviour.
Provide the calf with ad-lib access to clean, fresh water.
Clean the bedding area regularly.

Dehydration (%)	Behaviour	Suck reflex	Skin tent (seconds)	Sunken eyes	Mouth	Approx. oral electrolytes (litres)
1-5	Bright and alert, standing and moving around	Normal	1-4	Minimal	Moist	2-3
6-8	Less active, sitting down more	Usually reduced	5-10	Separation of eyeball to lower eyelid margin by 2-4mm	Sticky	3-5
9+	Lying down, reluctant to move	None	11+	Obvious separation of 5mm+	Sticky-dry, cold	Requires IV fluids - call vet

Assessing dehydration

When to seek veterinarian advice

Calves that are over 8% dehydrated (i.e. will not stand, poor or absent suckle reflex, cold, dry mouth, severely sunken eyes) cannot be properly rehydrated with oral electrolytes. Urgent veterinary attention is critical to provide intravenous fluid treatment.

Example fluid calculation

A 40 kg calf which is 1–5% dehydrated with a moderate scour requires the following daily fluid volumes:

Maintenance: 4 litres
Correct dehydration: 2.5 litres
Ongoing loss: 2 litres
Total: 8.5 litres.

If this calf is still drinking 4.5 litres of milk per day it requires 4 litres (8.5 minus 4.5) of oral electrolytes to meet daily needs and correct dehydration.

Scouring dairy calves under 14 days of age typically require a total of 6–8 litres of fluid intake per day.

If calves do not drink the electrolyte, then they can be given them via an oesophageal feeder (‘tubing’), but only if the calf is relatively alert.

The key to success

Review each calf, each day

One day of intense treatment is usually not enough to guarantee success. Assess each treated calf daily and adjust its treatment (oral electrolytes/milk/other) daily. Monitor the calf’s behaviour and the presence or absence of a suck reflex to guide treatment decisions.

Continue feeding milk to scouring calves

Maintaining sufficient energy intake is crucial to ensuring good outcomes for calves with scours. Even if good quality electrolytes containing glucose are used, they will not prevent energy deficiency. A litre of electrolytes will contain around 1.8MJ, compared to a litre of full fat cow’s milk containing 2.5MJ. It is crucial calves continue to be fed milk when they have scours. Continuing to feed milk improves recovery, growth rates, intestinal function and fat stores.

It is important to follow recommended wait times between milk and electrolyte feeds. Electrolytes are designed to support hydration and recovery but feeding them too close to milk can interfere with normal digestion. As a general guide, allow at least 2–3 hours between milk and electrolyte feeds, unless otherwise advised. Always follow the instructions on the product label, as formulations can differ and some are safe to feed ad-lib alongside milk feeds.

Calf scours refers to diarrhoea in calves. It is not a disease itself, but a sign that something is disrupting normal digestion. Scours can quickly lead to dehydration, so early identification and treatment are important.