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                    John Gay, DVM PhD DACVPM               AAHP                  FDIU             VCS

Calf Scour Slides


The following are versions the text slides I presented in VMS 261 Accidents and Disease lectures. At student request, these are presented here for their use and do not constitute veterinary advice.

Calf Scours Objectives:

What is it and how it "works"

What I as a veterinarian will recommend to:

Treat a calf with the problem

Prevent the problem from occurring

What is it?

“The discharge of more fluid than normal fecal matter from the bowel, often more frequently than normal.”

With this is lost more water and important electrolytes (salts) than are taken in.

Normal Fluid Balance

Physiology of Diarrhea

Normal cycling of body water into and out of intestinal tract is disrupted.

Normally considerably more fluid is secreted into the intestine and reabsorbed than is ingested.

Two main forms:

Excess secretion (hypersecretion) into intestine, normal reabsorption back out

Ex: E. coli K99

Normal secretion into intestine, reduced (malabsorption) back out

Ex: Most other infectious diarrheal agents

Diarrhea Imbalance - Hypersecretion

Diarrhea Imbalance - Malabsorption

Results of Diarrhea

Body fluid loss => Dehydration

Signs: Skin "tents", mouth isn’t slick, limbs and ears are cold, eyes sink and a gap appears between the eyeball and inner lid.

Urine output drops or stops

Body electrolyte (salts) loss and imbalance

Heart and skeletal muscle function affected

If shifts are severe enough, heart stops

Depression occurs

Most Important

Detect scouring calf before fluid loss becomes profound so oral replacement is still effective.

Replace lost body fluid and electrolytes in large enough quantity often enough that loss does not become profound.

Early Fluid Loss (<5% BW (body weight))

Calf is standing, skin "tents" for 4 seconds or less, eyes are bright, oral membranes are moist.

To eveluate skin tenting, twist a large fold of loose skin in the neck area or gently pinch an upper eyelid

Calf will suck electrolyte solution from a bottle

Leave calf on milk and add several 2 quart electrolyte feedings per day until scouring slows.

Even though nutrient absorption is incomplete, the calf needs what it can get from the milk.

Old recommendation to take calf off of milk is wrong.

Moderate Fluid Loss (7% BW)

Calf is dull and lying down but upright, skin "tents" for 5 seconds, eyes are sunken slightly with a slight gap, limbs are cold, oral membranes are warm but sticky.

Calf needs 1/2 gallon of warm high energy electrolyte solution (e.g. Entrolyte HE) by stomach tube (esophageal feeder) twice several hours apart to survive.

These solutions contain high levels of glucose to provide energy and other components to promote absorption.

Calf needs to be moved to a warm area where it can be monitored.

Severe Fluid Loss (>9% BW)

Calf is lying flat in a coma, skin stays "tented", eyes are deeply sunken with a big gap, limbs are cold, oral membranes are cold, pale and dry to touch.

Only 1 gallon of special fluids by IV drip soon will save the calf; SQ and oral fluids won’t be absorbed because circulation is too poor.

Take calf to veterinary clinic immediately.

Fluid Replacement

Enough balanced electrolyte fluids must be given to:

Replace % of body weight (BW) lost

Meet maintenance requirements (50 ml / kg BW per day)

Keep up with ongoing loss of 1 to 4 Liter per day in the diarrhea.

For a 7% dehydrated 80 lb calf, this is 6 to 9 quarts of electrolyte solution the first day.

The most common mistake is to give too little; if too much is given, the calf will urinate it away.

One of the signs that enough is being given is that more normal large volume urination resumes.

Commonest Infectious Diarrheal Agents in Young Calves:


Escherichia coli (E.coli) strains
Salmonella serotypes dublin, typhimurium, and others





Key E. coli Characteristics

Normal gut flora of all mammals so E. coli is ubiquitous (everywhere).

Three disease forms:

Colisepticemia - any strain:
Enterotoxigenic - specific strains (K99 and others).
Enteropathogenic - specific strains.

A most common cause of calf death.

Because the organisms involved in calf scours are usually highly antibiotic resistant, OTC antibiotics are usually not effective.


E. coli spreads from the gut through calf’s body and causes abscesses in the brain, eyes, kidneys, and joints.

Occurs when newborn calf ingests it in manure, mud or other material before or along with getting colostrum.

Virtually impossible to treat successfully.

Prevented by calving in clean, dry areas, cows having clean udders, and keeping colostrum clean and refrigerated or frozen.

Enterotoxigenic E. coli (ETEC)

Specific strain (K99) attaches to intestinal cells and causes a hypersecretory diarrhea.

Toxin turns on cell’s fluid pump which in turn pumps large amounts of fluid into the gut

This process can pump so much fluid into the gut that the calf dies before the external signs of diarrhea appear.

Almost the only diarrhea that occurs within first 3 days of life, often in first day.

Prevented by feeding colostrum containing K99 antibodies.

Cow vaccine available.

Enteropathogenic E. coli (EPEC)

Specific strains attach very tightly to gut wall and secrete various toxins, causing both excess secretion and malabsorbtion as well as general systemic effects on the calf.

No vaccine.

Corona & Rotaviral Diarrhea

Virus kills cells of intestinal villi, leading to malabsorbtion diarrhea.

Infected calves begin shedding 1011 virus per gram of feces about 3 days after infection.

Carrier cows in the herd shed low numbers of virus.

Virus survives in the environment for weeks.

Vaccines are available although not always efficacious.

Antibiotics are ineffective (virus).

Salmonella Diarrhea

Infected calves can shed the organism in feces, urine, saliva, and nasal secretions, contaminating everything they touch and everything that touches them (hands, esophageal feeders, nipples, ...).

Salmonella survives in the environment for months. Only direct sunlight kills it in the environment.

Because of antibiotic resistance, OTC antibiotics are usually not effective.

Salmonella Diarrhea


Depress the normal bacterial flora, making the animal more susceptible to infection and perhaps prolonging the diarrhea.

Are required if infection is systemic.

Current commercial vaccines are of questionable effectiveness.

This is a zoonotic disease, meaning that humans can get it!

Cryptosporidial Diarrhea

Ubiquitous organism that survives for months in the environment.

No antibiotics are effective.

Not killed by most disinfectants at practical concentrations.

Can be transmitted by dust in the air.

This is a zoonotic disease, particularly for the immunocompromised.


Most diarrheal agents:

Are ubiquitous.
Survive well in the environment.
Infections aren’t curable with drugs.
Establish carrier states in herdmates.

How do you reduce clinical disease?

Focus Areas for Prevention

General Principles

Maximize the calf’s natural resistance and acquired immunity (colostrum) prior to exposure.

Minimize dystocia, maintain proper nutrition and body condition of dam in critical third trimester of pregnancy.

Delay and minimize the infectious dose that the calf is exposed to.

As most of these agents are ubiquitous (in most herds), calf must eventually acquire the infection and develop an active immunity.

Minimize exposure dose by minimizing density of susceptible calves.

Minimize environmental survival of infectious agents by maximizing drying and exposure to sunlight of potential infectious material (feces)

Work with "Mother Nature" by exploiting the opportunities in the disease process:

Example: Viral Calf Scours

Facts about viral calf scours

Some cows are chronic carriers, intermittently shed low numbers of the viral scour agents.
The agents survive very well in the environment.
The incubation period for these in baby calves is usually around three days.
Scouring baby calves infected with these shed them in very high numbers, contaminating everything around them.
Heifers' calves are more susceptible than cows' calves.

Reducing Exposure - Beef

Move cows and heifers to separate calving area several weeks before calving.

Skin and hair of cows on winter feed and bed ground will have infectious agents shed by carrier cows.
Heifers have poorer colostrum.
Heifers need more supervision.

Reducing Exposure - Beef

1 Day after calving, move pair to large pasture area to spread out.

Exposed calf takes about 3 days to begin shedding agent in large numbers.

If scours develops in a group, leave all of that group in place but turn out new pairs to a new pasture.

More infected calves are subclinical shedders than are clinical cases (The Iceberg Principle).

DO NOT bring in purchased calves to replace dead calves.

They are often colostrum deprived and usually have been exposed to the full gamut of infectious agents.

Reducing Exposure - Dairy

Within first day, move calf to a cleaned individual hutch that isolates the calf from contact with and the air space of other calves.

Work has shown that the more air space each individual calf has and the more distance away from other calves, the less disease that they will have.

Sanitize anything that contacts the mouth of a calf prior to that contact (bottle nipples, esophageal feeders, pill guns, hands).

Reducing Exposure - Dairy

After weaning from milk, group by age in progressively larger groups

1 to 7 to 14 to 28

DO NOT hold back calves on the basis of small size; these are often carrier animals that will infect younger groups.

Group poor doers separately if they aren't advanced with their own group.

Acquired Immunity (Colostral Antibodies)

Due to the nature of the bovine placenta, calves are born without any antibodies.

They are needed to fight infection.

They are in the colostrum (first milk) produced by the dam.

These antibodies provide "passive immunity".

Work has shown that the higher the amount of these colostral antibodies absorbed by the calf, the less the disease severity and duration that they will experience.

Colostral Antibody Absorption

Colostral antibodies cross the calf's gut wall into the blood stream where they are an important component of the calf's immune system.

Occurs best during for the first hours of the calf’s life.
With the passage of time before feeding, less will be transfered.
Stops completely after the first day.

Note: Anything else in colostrum (bacteria!) is also absorbed indiscriminately.

You must keep colostrum and colostrum feeding equipment clean.

Methods of Feeding Colostrum

Natural Suckling: (only practical option for must beef cattle)

Highly variable colostrum intake
No opportunity to select high concentration colostrum
Frequently delayed colostrum intake, which lowers amount absorbed
30% to 80% of calves will have insufficient passive antibody levels to fight infection well.

Artificial Feeding:

Management policy controls colostrum intake amount
Selection of high quality colostrum is possible
Managment policy controls time of ingestion
10% to 20% of calves will have insufficient passive antibody levels to fight infection well.

Tubing with an esophageal feeder is usually more efficient and effective than bottle feeding if it is done carefully.

Selecting and Feeding Colostrum


Soon enough:

State to employees “Within 2 hrs. of birth” to give sense of urgency!

Volume enough: (Use esophageal feeder)

4 quarts (Holsteins)

The old recommendation of 2 quarts is too little for the modern Holstein calf.

Concentration enough:

Select first feeding colostrums from those cows producing less than 20 lbs. total (2 1/2 gallons) of colostrum at first milking.

The colostrums from cows producing more that 20 lbs are often too dilute for the calf to get enough passive antibodies to fight disease well.

Select colostrums that are greater than 50 mg / ml on colostrometer

Handling Colostrum - Dairy

Colostrum must be handled like grade A milk.

Disease causing bacteria will grow just as well in it as they do in milk.

These bacteria are transferred with the colostrum into the blood stream.

Harvest it into sanitized containers and refrigerate or freeze it if not used immediately.

Don’t pool - BLV, Salmonella, and Johnes are transferred by colostrum.

If the herd has a known Johnes or BLV problem, keep track of which calves are fed colostrum from a dam.


Because colostrum fights disease, it can be handled with dirty equipment and held at room temperature - FALSE!

Colostrum only fights infection when it is in the calf!

Bacterial contaminates multiply at least as rapidly in colostrum as in milk.

When warm, they can double in number every 30 minutes.

Anything that must be done to preserve milk quality must be done to preserve colostrum quality.

Cleaning & Disinfection

Thorough rinsing and cleaning is the first step, whether hutch, hands, or nipples.

Remove all organic matter (feces, blood, milk, milk stone, milk fat, saliva).

Organic matter protects infectious agents from the action of disinfectants (chemical or direct sunlight).

Soap, water, and scrubbing are the most important; mechanically removing the agents.

Chemical Disinfection

Use a disinfectant with labeled effectiveness against target agents.

Many commonly sold as disinfectants are not effective.

Environmental surfaces - One Stroke, Environ.

Tissue contact - Nolvasan or tamed iodine.

Allow adequate contact time (temperature dependent) at sufficient strength.

Organic material (milk, manure) inactivates most disinfectants, especially chlorine-based ones.

Chlorine begins evaporating when mixed.

Colostrum substitutes

Dietary Scours

Literature References - Calf Scours

Hunt, E (ed.). Symposium on Calf Diarrhea. The Veterinary Clinics of North America: Food Animal Practice. 1(3), 1985. WB Saunders Co.

A volume of 13 papers reviewing calf diarrhea, its causes, treatment and prevention, including one on milk replacers and their components.

Roy, JHB. The Calf, 5th ed. Vol. 1 Management of Health. 1990, Butterworths. 258 pp.

Detailed description of calf immunity and post-natal disease, particularly diarrhea.

Internet References - Calf Scours

Keep Them Alive (Nova Scotia Newsletter 5(5) MacKay, RD)


Calfhood Scours (D Marcinknowski, U Maine)

Electrolytes Are The First Line Of Defense For Treating Scours (D Marcinknowski, U Maine)

For Additional Information:

Calf Management - Birth to Weaning (dairy calves - T Brown, Tarleton State Univ)

Calf Scours: Causes, Prevention and Treatment (NebGuide)

Disease Protection of Baby Calves (colostrum in beef calves - Oklahoma State)

Electrolyte Treatment for Scouring Dairy Calves (KG Bateman, Ontario)

Neonatal Calf Diarrhea (KG Bateman, Ontario)


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