In the February and March issues of Progressive Cattleman, I shared with you my top 10 beef cow-calf nutrition myths. In this issue are the first five of my top 10 beef cow-calf management myths. Click here to read part 2.

Midla lowell
Dairy Technical Services Veterinarian / Merck Animal Health

Myth 1
“I’ve treated this calf with an antibiotic and it is not getting better. Therefore, I need a stronger antibiotic.”

When a small hammer doesn’t work, what do most of us do? We get a bigger hammer. Antibiotics are not like hammers. Antibiotics are like screwdrivers. You can’t put a slotted-head screw in with a Phillips screwdriver.

The bacteria you are trying to kill are either susceptible to a particular antibiotic or not – like a screwdriver fitting a screw head or not.

Thus, just like there is no such thing as a stronger or weaker screwdriver, there is no such thing as a stronger or weaker antibiotic. Often, good old penicillin may be the most appropriate antibiotic.


It is important to remember there are many potential reasons an animal may not respond to antibiotic therapy in a way that is satisfying to us. Examples include:

  • Inappropriate expectations: An animal with bovine respiratory disease, if detected early, may still be in the viral phase of the disease process. Antibiotics kill bacteria, not viruses.

    It is probably appropriate in most cases to treat these animals with an antibiotic to prevent the bacterial pneumonia that very commonly results from the viral infection. But remember, the animal still has to fight off the virus on its own and this may take a few days.

  • Incorrect diagnosis: I can’t tell you how many times I have been presented with a steer with a kidney stone blocking its ability to urinate that was treated the day before with an antibiotic because it was “sick.”

Myth 2
Antibiotics are the most important thing when treating a calf with scours (neonatal diarrhea).

The vast majority of calves that die from scours die from dehydration. Thus, rehydration/fluid therapy is the most important treatment. Oral fluids will effectively treat most calves, but some calves may require IV fluids.

I have seen IV fluid therapy take a calf that was flat out and near death to standing and nursing in as little as 24 hours.


  • Calves with scours (neonatal diarrhea) are often acidotic. That is, the pH of their blood has moved down out of the normal range.

    Thus, in general, it is a good idea to use an electrolyte/oral rehydration product that contains either sodium bicarbonate or a similar buffer as one of the main ingredients.


  • Think of yourself as a donut: A donut has an outside on the outside, but it also has an outside on the inside. Our skin is our barrier to protect us against invaders from the outside.

    Our gut wall has two functions – the first is, of course, to absorb nutrients. The second is to be our “skin” to protect us against invaders from the inside. When a calf has scours, the “skin” function of the gut wall is often compromised, and bacteria may gain access to “rest of calf.”

The preceding story is why your veterinarian may recommend a calf with scours be put on an antibiotic – to protect it against bacteria in its bloodstream that may get there during the time of compromised gut wall defensive ability.

It is very important to remember, however, that the antibiotic is most likely not fighting the bug that is causing the scours. It is instead protecting the rest of the calf while the calf has scours.

With the exception of Coccidia in older calves, most of the bugs that cause scours are not likely to be killed by most antibiotics, on most days anyway.

Myth 3
If a vaccine is available, then it must be effective at preventing what it is supposed to prevent.

The USDA is responsible for approving cattle vaccines. There are five “levels” of label claim that may be granted to a vaccine by the USDA. Examples include “for prevention of disease due to …,” “aids in prevention of disease due to …” and “as an aid in the control of disease due to ….” There are stringent standards a vaccine must meet for each level of claim.

There are only minimum requirements that must be met regarding efficacy for a vaccine to be approved at the lowest level of label claim. There have been many examples over the years of vaccines that were either minimally effective or not effective at all.

Some of these vaccines are still manufactured and marketed. Just because a vaccine is available does not mean that it is going to necessarily do what you expect it to do. That is, you can’t say, “I vaccinated against disease X, therefore I don’t have to worry about disease X anymore.”

The fact that there are only minimum requirements that must be met regarding efficacy to gain a vaccine approval from the USDA is not a bad thing. It is appropriate that the USDA err on the side of approval so a vaccine can get used more widely and thus be subjected to the test of time.

If the USDA requirements for approval were to be ramped up, then vaccine manufacturers would be severely dissuaded from investing in new vaccine development.

Myth 4
Vaccination is always 100 percent effective/100 percent protective.

Examples of reasons this can be false:

  • The heat-humidity index is too high (greater than 85ºF) on the day of vaccination. Note: It could be 79ºF but humid. If you are sweating, then you probably should not be vaccinating.

  • The animal being vaccinated is selenium- or copper-deficient on the day of vaccination.

  • The animal being vaccinated is parasitized on the day of vaccination. There is a growing body of evidence that this can be significant. Think about calves grazing summer pastures and accumulating a parasite load.

    We deworm them and vaccinate them on the same day either at weaning or (infinitely better) in preparation for weaning. It may make the vaccination much more effective if we were to deworm them prior to vaccinating them.

  • The animal went too long since the last time it was vaccinated, so the vaccination that you are giving is not really a “booster.”

  • The number one reason vaccinating the dam to prevent scours in the calf fails is that the calf did not get an adequate volume of colostrum or received colostrum too long after it was born for the colostrum to be adequately absorbed. Remember, the antibodies against the scours pathogens that we stimulated the dam to produce must still get passed to the calf via the colostrum.

  • The antigens in the vaccine that stimulate an immune response are different than the antigens on the surface of the bacteria/viruses/etc., to which your cattle are exposed.

    That is, the bugs attacking your animals “look” different than the bugs in the vaccine to your animals’ immune system. Thus, your animal was not prepared by the vaccine against the bug to recognize it and so was not prepared by the vaccine to deal with it.

  • The vaccine got warm at some point before it was injected. The dash of your pickup is not an appropriate place to store a bottle of vaccine.

Myth 5
“Re-vaccinate annually” on the label of the vaccine bottle means the vaccine imparts 365 days of duration of immunity.

“Re-vaccinate annually” is standard language allowed to be printed on the label of vaccines regardless of the actual duration of the immunity that results from the vaccine.

Check with your veterinarian or the manufacturer of the vaccine regarding the actual duration of the immunity induced by a particular vaccine. Many vaccines need to be administered more than once per year in order for the animal to be kept protected.  end mark

Lowell Midla
  • Lowell Midla

  • Assistant Professor
  • College of Veterinary Medicine
  • Ohio State University
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