Preserving drug integrity
The direct benefits of responsible drug use are safety to animals, violative residue avoidance,
better drug performance and preserving the drug's effectiveness. Saltman notes that respect and
understanding of proper drug use must be a training focus for everyone working on a dairy, from
the owner to the frontline workers, who often are the ones giving the shots.
What's more, today's drug use could have farreaching implications on tomorrow's dairy industry.
"One thing that allows the pipeline of new drugs to function is how responsibly we use the drugs
we have today," notes Apley. "If regulators have confidence that a drug's label will be followed,
there is a greater chance that they will allow new veterinary compounds to become available. If
not, then our pipeline could dry up pretty quickly."
All the more reason to follow product label directions, seek a veterinarian's advice, and look for
ways to ensure compliance with proper antibiotic dose and duration.
Survey says... compliance is a real issue
Researchers from Penn State and Michigan State Universities surveyed more than 100 dairy
herds in Pennsylvania about antibiotic usage.1 The results point to potential issues with prudent
antibiotic use.
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Only 50 percent maintained treatment records
Only 21 percent had written plans for treating sick animals
Only 32 percent sought veterinarian advice before
administering antibiotics
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Only 24 percent said they always completed the labeled course
of treatment
"Although it's just one small group of dairy farms, the results of the survey may be indicative of
a larger problem across the country," says Roger Saltman, DVM, MBA, manager, dairy
veterinary operations, Pfizer Animal Health. "We need to find out how widespread this problem
is and encourage the industry to start correcting it with the proper guidance and tools. New
strategies for the proper use of antibiotics are needed."
1 Sawant AA, Sordillo LM, Jayarao BM. A survey on antibiotic usage in dairy herds in
Pennsylvania. J Dairy Sci 2005;88:2991-2999.
Dose & Duration
Compliance Is Critical For Antibiotic Success.
"When all else fails, read the directions." You've probably recited this motto when assembling a
Christmas gift or repairing a piece of farm equipment. But the rule applies, too, when using
veterinary medications.
"We have access in animal agriculture to many sophisticated antibiotics and other medications,"
says Mike Apley, DVM, PhD, associate professor and pharmacologist at Kansas State University
College of Veterinary Medicine, Manhattan, Kan. "With that access comes a high level of
responsibility to use those drugs correctly. Ignoring that responsibility could come with a heavy
price to pay down the road."
Apley says accurate diagnostics and regular monitoring of disease pathogens on dairies must be
the cornerstone of responsible drug use. Both require an ongoing relationship with a skilled
veterinarian who can establish and monitor those diagnostic protocols. Veterinarians also can
perform the next step of evaluating antimicrobial sensitivity—matching the best drug to the bug
with which you're dealing.
In the absence of that homework, selecting and administering drugs "on instinct" can lead to
unnecessary costs, poor treatment outcomes, and the potential to create new populations of
bacteria that are less sensitive to antibiotics.
Follow the label
Two of the other most common mistakes made using veterinary drugs is not administering the
correct dose for the animal's size or disease condition and/or not administering as many
treatments as the label indicates.
"We should use antibiotics only when they are required but, when they are required, they need to
be used at a sufficient dose and duration to ensure that the infection is completely cured," says
Roger Saltman, DVM, MBA, manager, dairy veterinary operations, Pfizer Animal Health. "Just
because an animal begins to show clinical signs of improvement like brighter eyes, decreased
fever or better appetite, it doesn't mean the infection is completely cured."
Saltman compares the difference between a clinical cure (animal looks better) and a more
complete, bacteriological cure (all the bacteria are gone) to a bonfire. The infection starts small,
like tinder being lit by a match. More of the tinder is engulfed by flames, larger logs begin to
burn. Saltman says an antibiotic is like the water with which we try to put out the flames. The
flames die fast, but the fire is still smoldering.
"We need to dose effi ciently and keep pouring it on so that the entire ‘fire' is extinguished and
any smoldering embers aren't still around to take off again," he adds. "The durations
recommended on drug labels are based on thorough research, including clinical trials. They are
there for a reason."
Veterinary drugs with more than one label indication may inadvertently pose challenges for
antibiotic compliance in a dairy producer's day-to-day routine. "EXCENEL® RTU (ceftiofur
hydrochloride) Sterile Suspension, for example, is labeled for foot rot, pneumonia and metritis in
dairy cattle," says Saltman. "While the course of therapy for foot rot and pneumonia is 1 to 2 cc
per 100 pounds of body weight for 3 to 5 days, the metritis course of therapy is strictly 2 mL per
100 pounds for 5 days. Using a lower dose and/or giving it for fewer than 5 days to treat metritis
can produce disappointing results." As with all drugs, EXCENEL RTU should not be used in
animals found to be hypersensitive to the product.
The outcome of drug therapy can be impacted by straying from the label in other ways as well,
including:
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Changing the site of administration
Increasing or decreasing the frequency of administration
Administering a larger volume per injection site than indicated
on the label
"Some people use penicillin pretty indiscriminately, for example," says Apley. "In that case, you
can create some incredibly long milk discard times. That's a huge cost, in terms of lost milk, and
the risk of creating a violative drug residue." Penicillins and cephalosporins should not be given
to animals that are known to be hypersensitive to the drug.