Join well respected veterinarians as they discuss bovine neonatal diarrhea, or baby calf scours, in this hour-long program. Appropriate for beef and dairy producers, the program covers the many factors contributing to scours: cow/heifer health and plan of nutrition, calving ease, environmental factors, management practices, infectious causes of scours, and – perhaps most important – what can be done to help prevent scours in your calf crop. Learn more about this complex disease that costs producers millions every year.

To Download:
Right Click, and select 'Save Target As..'
guardian vaccine

GUARDIAN vaccine is administered to cows and heifers to help prevent infectious neonatal scours in calves. It is the broadest coverage available in a scours vaccine. GUARDIAN stimulates production of protective antibodies in cows and heifers, and they are passed to the calves in colostrum. Antibody-rich colostrum should be consumed within the first six hours and continued through the first 24 hours of a calf's life. The disease-fighting antibodies can only be absorbed at that time, and they can make a difference between life and death.

Vaccination with GUARDIAN is simple and convenient.

Guardian Dosing and Administration - Product Label
Dosage & Route2 mL SC
Primary Dose12 weeks precalving
Booster Dose3-6 weeks after primary dose
Annual Revaccination5-7 weeks precalving
Bottle Sizes20 mL (10 doses) & 100 mL (50 doses)
Preslaughter Withdrawal60 days

Vaccinating cows and heifers with GUARDIAN can give you peace of mind, less labor during calving season, and a healthier calf crop.

Finally reliable scours protection
scours education

Vaccination is Your Ally

Scours is a life-threatening disease. Keep it from impacting your calf crop or your doctoring budget by vaccinating with GUARDIAN. Baby calves are highly vulnerable to the many causes of neonatal diarrhea, more commonly called calf scours. Vaccination can help you overcome those many causes.

3 Major Causes of Scours

If not controlled properly, all can weaken the calf, resulting in a failure to resist serious disease.

1. Pathogens - Infectious Agents that Cause Scours

Scours can be caused by viruses, bacteria and parasites. Disease conditions are created when these agents damage the villi that line the intestinal tract. This damage prevents normal absorption of fluids and nutrients.


Rotaviruses cause pasty, sometimes liquid scours in calves a few days old. They generally do not cause significant mortality but create depression and dehydration by compromising the calf's ability to absorb nutrients and fluids. This also stresses the immune system and allows other opportunistic pathogens to invade the gut. Coronaviruses affect slightly older calves, usually five to 10 days of age. Diarrhea is more intense and bloody. Coronaviruses are much more likely than rotaviruses to cause a fatal infection.


Escherichia coli bacteria are a common cause of calf scours. The E. coli K99 strain is capable of causing severe, very liquid, yellow diarrhea in calves one to two days old. Other bacteria (e.g., Salmonella) may cause opportunistic infections when the gut has been damaged by other pathogens, such as rotaviruses and coronaviruses.


Cryptosporidium is the principle parasite capable of causing scours in very young calves, with a pasty, yellowish diarrhea that is sometimes blood-streaked. Most often, Crypto acts in conjunction with a virus or bacteria. Cryptosporidia can also infect humans. Another parasitic infection more common in older calves is coccidiosis.

2. Environmental Factors

The pathogens (viruses, bacteria and parasites) that cause scours are shed in the feces of adult cows or sick calves. The organisms can then persist in the environment for various lengths of time. The table below indicates the duration and persistence of the various scours agents in different environments. As you can see in the table below, it is virtually impossible to eliminate the sources of all pathogens.

Rotaviruses — Coronaviruses

Duration of excretion by sick calvesClinical + 1 to 2 days2 to 6 days10 to 40 days10 days
Persistence in the feces2 to 3 months5 to 6 months6 months to 2 years1 to 2 years
Bedding2 to 3 weeks5 months4 months1 to 2 years
Hard-surfaced area6 to 12 months1 to 2 years

3. Management Factors

The management goal is to reduce the probability of infection by limiting the contact with shedding animals and to keep the calving area as dry and clean as possible. For example, a calf born in May in a large pasture with plenty of open space has much less chance of becoming infected than will a calf born in March in a concentrated calving area, where it is immediately exposed to many pathogens. The more animals held per acre of calving area greatly increases the pathogen contact and therefore the severity of disease challenge. When the level of immune protection is overcome by the challenge level of the environment, severe outbreaks will result. In addition, combining calves of different ages aggravates the problems. Older animals can transmit pathogens to younger ones without being sick themselves.

Click the arrows to view a competitive comparison of ScourGuard 4KC and GUARDIAN.

Colostrum, Antibodies, and GUARDIAN Vaccine

At birth, a calf has virtually no protective antibodies in its system, and it has enormous nutritional needs. Colostrum, rich in antibodies and nutrients, is vital to the survival of every newborn calf.


Toward the end of pregnancy, antibodies in the bloodstream of the cow begin to concentrate in the udder, which is forming colostrum. Colostrum contains high levels of antibodies, nutrients, vitamins and minerals. During the first few days after calving, the colostrum transitions to milk, with a composition that rapidly declines in antibodies and nutrients until it stabilizes at the level of normal milk needed for the sustained growth of the calf.


In the last few weeks before calving, protective antibodies circulating in the cow's blood become concentrated in the udder. During pregnancy, these maternal antibodies cannot cross the placental barrier to reach the fetus. At birth, then, the calf has virtually no antibodies to protect itself. The neonatal immune system begins to recognize infectious agents and manufacture its own antibodies, but the immune system will not be capable of true protection until about a month after birth. During this time, protection by maternal antibodies is essential. And the only way for the calf to get them is by consuming antibody-rich colostrum. The passage of antibodies in colostrum from dam to calf is called passive transfer. Failure of passive transfer is a major cause of neonatal disease.

Jolene Schropfer

"We struggled with Clostridium in our area, and once you have it on your property, it's really a challenge to deal with. There's nothing more frustrating than having a healthy heifer calf that's six days old, doing very well, and then at the next feeding, she's dead because of Clostridium.

"We were vaccinating with another scours product before, and you can look through our records to see which calves we haven't lost to Clostridium compared to when we were vaccinating with the other product. I will definitely keep using GUARDIAN."

Jolynne Schroepfer
Nagel Dairy
Deerbrook, WI

Brian Schick

"The first year I used GUARDIAN I didn't treat one calf for scours out of 300 calves. The year before, I treated 10 or 15 with scours.

"GUARDIAN has worked wonders for us. With 350 cows, you don't have time to deal with 30 or 40 sick calves. And if you save one or two calves, the cost of the vaccine is covered.

"As far as I'm concerned, GUARDIAN is worth every penny."

Brian Schick
Schick Farms
Densmore, KS

Dr. Russ Weston

"There are a whole lot of things that need to be administered at dry-off, so by giving GUARDIAN prior to that time, we spread those out a little bit.

"Plus, there's an extra coronavirus serotype in GUARDIAN and there's extra protection against Clostridium. Because there are more serotypes in GUARDIAN than in other vaccines, GUARDIAN is beneficial in controlling scours in dairy cattle.

"We like the convenience, timing and broader spectrum of GUARDIAN over other vaccines. I will continue to use and recommend it."

Dr. Russ Weston
Lena Veterinary Clinic
Lena, IL

Dr. Tom Cox

"I've used several products over the years, and most of them worked pretty well. When GUARDIAN came out, I went to one of Merck Animal Health's seminars and learned about the different types of coronaviruses in the products. That seems to be important. The vaccines I used before GUARDIAN did help with scours, but not totally. With GUARDIAN it seems like I'm getting total control.

"The bottom line is that people want convenience. They want to give a vaccine in the last trimester when they preg check the cow. You can do that with GUARDIAN."

Dr. Tom Cox
All Creatures Animal Hospital
Weatherford, OK