A Review Of Calf Scours
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Newborn calves are extremely susceptible to calf scours especially during the first 28 days of life. Bacteria and viruses attack the lining of the calf's gut. The result is often watery diarrhea, with the calf losing nutrients and fluids and becoming dehydrated.

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  • There are two main forms of diarrhea.
-- Excess secretion into the intestine and normal reabsorption back out.
         (Example -- E. coli K99)

-- Normal secretion into intestine with reduced back out (malabsorption).
Example -- most other infectious diarrheal agents)

  • Results of calf scours.
-- Dehydration -- skin tents, mouth dry, legs and ears cold, eyes sink, urine 
          output drops.

-- Body electrolyte (salts) loss and imbalance. Heart and muscle function 
  impairment and the heart stops.

-- The most common cause of calf death is due to E. coli infection.

  • More about Rotaviral and Corona diarrhea. 
-- The incubation period for calves is usually around three days.

-- Heifers' calves are more susceptible than cows' calves.

-- Virus kills the cells of the gut causing malabsorption scours.

-- Scouring calves shed millions of virus about three days after infection.

-- Carrier cows in the herd shed in low numbers.

-- Virus survives for weeks.

-- Vaccines are available. Vaccinate just before calving (heifers -- two  shots,
cows -- annual booster). Not always effective. Oral vaccine should be given in
the back of the throat before the calf sucks colostrum. Antibiotics won't kill a

  • More about cryptosporidial scours.
-- Crypto bug is everywhere and survives for months on the ranch.

-- Vaccines not available and antibiotics aren't effective.

-- Not killed by most disinfectants. Cleaning pens and corrals is the only way
  to reduce the challenge.

-- Can be spread by dust in the air. Humans can get this infection.

Scours Agent

Rotavirus (virus)

E. coli K99

Coronavirus (virus)

Cryptosporidia (protozoa)

Salmonella spp (bacteria)

Clostridium perfringens
Type C (bacteria)

Coccidia (protozoa)

Summary of Scours Agent
Age of Onset

Usually after 6 days -
can be 0-28

Most common at 1-5 days

Usually after 7-10 days -
can be 0-28

Usually at 7-21 days

Commonly at 1-7 days

Commonly at 7-28 days

Usually after 7 days


Mucus, watery brown or green diarrhea, blood

Effortless passing of yellow to white feces

Watery yellow feces

Watery brown or green feces with blood and mucus

Like E. coli, yellow to white feces (human infection also)

Sudden death (blood tinged feces)

Mucus and often bloody diarrhea

Table and information provided by: Bill Kvasnicka, University of Nevada-Reno Extension Veterinarian, 775-784-1377 or,
E-Mail: bkvasnicka@cabnr.unr.edu