Calf Scours in Newborn Calves: Causes, Early Signs, and When to Call Your Vet

Scours is diarrhea in young calves. It matters because of what comes with it: a scouring calf loses water and electrolytes quickly, and dehydration is what makes these calves so sick. According to the University of Minnesota Extension, scours is the leading cause of death in calves under one month of age, and dehydration is what kills them.

Most cases show up in the first three weeks of life. Penn State Extension notes that calves with infectious scours usually start showing signs between one and three weeks of age. That is the window when the protection a calf gets from colostrum is fading and its own immune system is still catching up.

Scours has two broad sources, and many sick calves have more than one going on at once.

Infectious Causes

Viruses, bacteria, and parasites all cause scours. The University of Minnesota Extension reports that rotavirus, coronavirus, and Cryptosporidium ("crypto") cause about 95 percent of infectious scours cases in calves under three weeks old. E. coli and Salmonella are also common culprits on some farms.

Every calf is exposed to these pathogens. Whether a calf actually gets sick often comes down to how big a dose it picks up from its surroundings, and how well its defenses were set up in the first hours of life.

Nutritional and Management Causes

Not every case starts with a germ. Common management triggers include:

• Not enough milk. A calf needs energy to grow and to fight off disease at the same time. Underfeeding is one of the most common causes of scours.
• Inconsistent feeding. Changing feeding times, milk temperature, or how milk replacer is mixed stresses the calf's gut.
• Milk replacer mixed too strong. Over-concentrated replacer pulls water into the gut and causes diarrhea on its own.
• Stress. Transport, weather swings, dehorning, and switching milk sources can all bring on short-term scours.

Nutritional scours often clears once the stress is removed, but it can still dehydrate a young calf just as quickly as an infection, so these calves need close watching too.

A calf on an all-milk diet should not have firm manure. Loose manure alone is not scours.



• Normal: semi-formed to loose, about the consistency of pudding or yogurt, and it sits on top of the straw bedding.
• Scours: close to the consistency of water, and it runs right through the bedding.

Penn State Extension suggests scoring manure on a simple scale, where a "1" is pudding-like, a "2" is yogurt-like, and a "3" (roughly maple syrup, loose to watery with a strong odor) counts as scours. Scoring every calf the same way helps your whole crew make the same call.

Color gets a lot of attention, but the University of Minnesota Extension points out that manure color usually has little diagnostic value unless there is blood in it. Blood in the manure is a reason to call your vet.

Early Signs a Calf Is Getting Sick

The best time to catch scours is before the calf stops eating. Watch for:

• Droopy ears, dull eyes, and a calf that seems depressed or slow
• A calf still lying down when the others are up
• A calf that needs coaxing to finish its bottle or bucket
• Faster, harder breathing (make sure you are not mistaking scours for pneumonia)
• Sunken eyes and dry gums

Attitude at feeding time is one of the most reliable early clues. A calf that normally drives into its bottle and suddenly needs encouragement deserves a closer look that day.

Because dehydration drives how sick a scouring calf gets, it helps to judge it quickly. Penn State Extension reports that a scouring calf can lose 5 to 10 percent of its body weight in water within a single day.

Two quick checks tell you a lot:

1. Skin tent test. Pinch a fold of skin on the neck and count how long it takes to flatten. Under 2 seconds is normal. Two to 6 seconds suggests moderate dehydration. Over 6 seconds suggests severe dehydration.
2. Gums. Healthy gums are pink and damp. White, dry gums point to significant dehydration.

Per Penn State Extension, fluid loss beyond about 8 percent usually calls for IV fluids, which means a call to your veterinarian.

Treatment decisions belong with your veterinarian, and every farm should have a written scours protocol worked out with them. A few principles show up in nearly every extension recommendation:

• Electrolytes come first. Oral electrolytes replace the water and salts the calf is losing. Mix them exactly as the label directs, because a solution mixed too strong can make scours worse.
• Keep feeding milk. Both Penn State and Minnesota Extension advise against pulling milk from a scouring calf. Electrolytes cannot supply enough energy on their own, and the calf needs that energy to recover. Feed electrolytes as separate feedings in addition to milk.
• Antibiotics are not automatic. Since most scours cases are caused by viruses or crypto, antibiotics will not treat the cause in most calves. Your vet will usually decide based on a rectal temperature and an exam.
• Pain relief helps. Scours is uncomfortable, and your vet can recommend an anti-inflammatory that helps a calf get back on its feet.

When to Call Your Veterinarian Right Away

Call your vet for any calf that cannot stand, will not suckle, has blood in its manure, has a temperature above 102.5°F or below 101°F, or is showing signs of severe dehydration. Those calves may need IV fluids that only your vet can provide.

Prevention works better than treatment, and most of it happens in the first hours of a calf's life.

• Colostrum, early and plenty. The University of Minnesota Extension recommends 4 quarts of clean, high-quality colostrum within the first two hours of life. A calf's ability to absorb antibodies drops every hour after birth
• A clean calving pen. Exposure starts the moment the calf hits the ground. Clean, dry bedding lowers the dose of pathogens a newborn picks up.
• Clean everything the calf can reach. Bottles, buckets, nipples, and hutches should be cleaned and disinfected between calves.
• Consistent, adequate milk. Same time, same temperature, same mix, every feeding.
• A cow vaccination plan. Work with your vet on pre-calving vaccines that improve the protective antibodies in colostrum.

Some producers also add a direct-fed microbial at birth as part of the day-one routine. That is where our product fits. Start Baby is a probiotic paste with a guaranteed minimum of 60 billion CFU per tube and a full panel of B vitamins, given as one tube within six hours of birth. It supports the gut in those first hours. It does not replace colostrum, clean housing, or your veterinarian's protocol, and it is not a treatment for a calf that is already sick.

If you are setting up a day-one routine for your calving season, the Start Baby 25 Pack is sized for steady year-round calving, and our FAQ page covers timing and dosing questions.

Keep a box of Start Baby in the calving pen so the first tube is ready when the next calf arrives. Shop Start Baby or call us at (223) 341-9188.

Most people who raise calves deal with scours at some point. The calves that come through best usually belong to operations that already have colostrum, cleanliness, feeding consistency, and a vet-approved treatment plan in place before calving season starts. Write your plan down, make sure everyone on the crew knows it, and keep electrolytes and your day-one supplies stocked.

Questions about fitting Start Baby into your calf program? You can read more about our family and how Start Baby started, or call our team at (223) 341-9188.