Antibiotic Use and Misuse In The Dog and Cat

The Pharmacy

PET MEDICATIONS…What are they for?

Learn about what goes on in the animal hospital’s pharmacy. New medications are available on a continuing basis to help improve the safety and efficacy of veterinary medications.

Pet medications and prescriptions need to be used with an understanding of their effects and side effects. Only fresh, quality pet medications should be used for dogs and cats… and then used only as directed. Keep in mind that any medication or drug may not be safe and effective for every individual dog or cat taking that substance. Here’s an example from human medicine: Aspirin is widely available without a prescription and billions of aspirin tablets are consumed worldwide every year. On rare occasions someone will have a bad reaction from taking aspirin. Does that mean that aspirin is “Bad” and that it shouldn’t be available to anyone? Does it mean that no one should ever take an aspirin just because a few people shouldn’t? Likewise with pet medications we need to be vigilant of undesirable side effects and should keep in touch with the dog or cat’s veterinarian when any questions arise regarding pet medications and their use. Visit this page to see why medications sometimes seem expensive.

Lets get acquainted with the Pharmacy by first getting to know
some interesting definitions…


Veterinarians frequently get calls about “expired” medications. The expiration date means the product shouldn’t be sold or dispensed after that date. It does NOT mean that the product becomes ineffective or useless on that date. Here’s an example…if you purchased a box of Heartgard with nine tablets in it on January first, and you see an expiration date on the box of April of that year, your impression might be that you have only four useful tablets in the box of nine. What the drug companies must do, though, is set the expiration date well in advance of the time when any effectiveness might drop off in order to take into account the time it takes the consumer to use the medication. So you can safely use a medication after the expiration date if you use it in accordance with the label instructions. In this example of Heartgard, the company knows it will take you nine months to use up the nine tablets and sets the expiration date to take that time interval into account. The expiration date takes into account the time span it will take the purchaser to use up the medication after it is purchased.


A side effect is any response that is not the desired effect of a drug or medication. So if an antihistamine is prescribed in order to decrease nasal congestion due to an allergy and the patient also experiences a sluggish and sleepy mood as well, the drowsiness is considered to be a side effect. Since most dogs and cats don’t drive or operate heavy machinery, the side effect of sleepiness may not be an important consideration. In fact, the side effect of the antihistamine might even be good. Maybe an antihistamine would be a good choice to use prior to a trip where the dog or cat would benefit from being slightly sleepy instead of barking or yeowling for four hours straight! So, side effects are conditions other than the one intended… but remember, side effects can be good, bad or inconsequential.


The strength of a medication is the concentration or weight of the substance. For example cats are often given Amoxitabs as an antibiotic. Usually they are given the 50mg (50 one-thousandths of a gram) strength tablet. Amoxitabs also come in other strengths such as 100mg, 200 mg and 400mg. The dose is the amount of the medication that an individual should take at one time. For on antibiotic the dose might be 8mg per pound of body weight and for another antibiotic the dose might be 25mg per pound. The dosage is the amount to take over a period of time. The prescription bottle might read 2 capsules every 8 hours until gone. This means that the doctor wants the patient to take two capsules at a time and repeat taking two capsules at eight hour intervals until all the medication is gone. (No, generally the time interval doesn’t have to be exactly every eight hours! Just try to come close.)


Take an ordinary raisin. Cut it up into 1000 equal parts. Each little part will weigh about 1 milligram. There are 464,000 milligrams in a pound. The fact that most drugs are measured in milligrams should alert you to the fact that sometimes very tiny amounts of a substance can be very powerful. Label instructions should be followed very faithfully.

An example of the imperfect world we face in veterinary medicine can be seen when a dog or cat experiences a reaction to a vaccination. On occasion, a potentially serious reaction can occur shortly after receiving an inoculation. The patient’s blood pressure drops, heart rate slows and the patient can loose consciousness. Rapid measures may be needed to save the patient. (I have seen this happen 3 times in 27 years of vaccinating dozens of dogs and cats on a daily basis.) There are those who will flatly state that vaccinations are “bad” for dogs and cats, not just because they can cause serious reactions but they also believe that the vaccines cause future chronic ailments. I wonder how many cases of Canine and Feline Distemper, or Canine Hepatitis and Parvovirus I would have seen, and how many dogs and cats would have died from these preventable diseases if I wished for a perfect world and didn’t vaccinate all those pets for fear of the occasional imperfection.

There are those in the Holistic community who will differ with some of the information here in the Pharmacy. Strictly Holistic veterinarians have their reasons for believing what they do and we all should keep an open mind when it comes to non-traditional ways to medicate ourselves and our pets. However, historical facts and unemotional data have proven beyond any reasonable argument that some drugs and medications have very powerful health enhancing effects. On the other hand, if you are looking for a perfect world where everything is predictable and 100% safe and effective…you won’t find that perfection in the Pharmacy or Lab.


The following article appeared in an issue of Dog World Magazine regarding the use of antibiotics in pets:


by T. J. Dunn, Jr. DVM

Returning to his lab one morning in 1928 after a two-week vacation, Scottish microbiologist Sir Alexander Fleming realized that one petri dish inoculated with Staphylococcus bacteria had been accidentally left open. About to dispose of the worthless moldy dish, he noticed a clear halo devoid of any bacterial overgrowth surrounding each mold colony. For some strange reason the bacteria weren’t growing in these small halos of agar surrounding the greenish mold. Curious, as all scientists are, he asked himself why not? Instead of discarding the “contaminated” petri dish, he explored the antibacterial properties of the unusual mold, called Penicillium notatum, and the rest is history.

Since Fleming’s discovery of penicillin huge strides have been taken in the research and development of wide varieties of antimicrobial chemicals, and researchers continue to seek newer, safer, and more effective methods of interfering with bacterial and other microorganism replication. One of the greatest challenges veterinary and human doctors face today is to make appropriate antibiotic selections that effectively help the patient recover from bacterial, yeast and fungal infections… and at the same time to not harm the patient.

How would harm come to a patient being administered antibiotics? One common example is the over-prescribing of antibiotics… using them when not really indicated. Recently a young Wirehaired Fox Terrier was presented to me because of sudden onset of loose, foul smelling stool. There was no history of the dog having eaten anything unusual, the diet was excellent, no intestinal parasites were evident on the fecal analysis, and the patient was not dehydrated, vomiting, nor acting depressed. The temperature was normal and abdominal palpation revealed a loose, gassy and non-painful character. My diagnosis was a viral enteritis… call it “intestinal flu” if you like. After discussing my diagnosis, and my preferred treatment of withholding all dog food for 24 hours, allowing plenty of fresh water, and simply allowing the dog to eat small amounts of yogurt every two hours until the following day, the owner asked “Aren’t you going to give him some antibiotics?”

I had to convince the concerned and skeptical owner that if my diagnosis was correct, this patient did not need antibiotics and in fact might develop a much worse diarrhea if we went that route. Plus, once an antibiotic is used in a patient there is the potential for that patient to develop a resistant population of bacteria. And someday, when antibiotics are truly needed, if that antibiotic is chosen as a treatment the infection may be refractory to the drug. What this patient needed was to have “good” bacteria reintroduced into the gastrointestinal tract so that the correct balance of bacterial flora could be reestablished. Antibiotic administration should be reserved for patients who truly need them. Indiscriminate or casual use of antibiotics may lead to bacterial resistance in a patient as well as set up the potential for a future allergic reaction to the drug.

Conversely, in urinary tract infections and in skin infection cases called pyoderma, long-term administration of antibiotics may be necessary to eliminate tough infections. Often, with pyoderma, antibiotics are actually under-prescribed. According to veterinary dermatologist Rusty Muse of Tustin, California, most pyoderma cases require an appropriate antibiotic for as long as six to eight weeks to be effective. Dr. Muse states, “The skin receives only 4% of the heart’s output so effective blood delivery of antibiotic concentrations have a much more difficult time saturating the skin cells in microbe-killing amounts than in organs well perfused with blood such as the liver. At our dermatology clinic we have discovered that about 10% of the ‘allergy’ patients are actually suffering from chronic pyoderma and have not responded well to antibiotics previously used. Sometimes that failure for an infection to clear is due to too low of a dose being given or the dose not being given as often as directed or for as long as directed. In some cases, especially if a culture and sensitivity have not been done, the antibiotic chosen may not be the best choice for the specific bacteria causing the pyoderma.

“There are four principles to keep in mind regarding appropriate antibiotic use,” continues Dr. Muse. “One is that the correct choice of antibiotic needs to be made for a particular infection. The second is the proper dose must be given. Third is that the dose must be given at defined intervals because some medications should be given once a day and others four times a day to achieve consistent and effective tissue levels of the antibiotic. And finally, the antibiotic needs to be given long enough to truly effect a cure.”

In general, most veterinarians select what they consider to be an appropriate medication, and if the results are not favorable, laboratory identification of the bacteria and testing for the bacteria’s vulnerability to specific antibiotics is done. This is termed “doing a culture and sensitivity”. Should this be done in every situation where an infection is discovered? According to Mark G. Papich, DVM, Professor of Clinical Pharmacology in the College of Veterinary Medicine at North Carolina State University, “For routine infections, empirical treatment with ‘first line’ drugs can be used without obtaining lab tests (culture and susceptibility tests) first. For refractory infections, or cases that are more serious and/or life-threatening, lab tests are recommended.”

Some failures of antibiotic administration might be due to early withdrawal of the drug by the owner when it appears that an infection has “cleared up”. Every veterinarian has experienced the exasperation of faulty owner compliance with prescription instructions. A typical scenario goes like this…the veterinarian sees a patient again for the same problem a few months after prescribing an antibiotic. A different prescription is suggested to fight the infection and the owner says “I’ve still got quite a few left from the last time, Doctor, should I just start those again?” Bingo! So that’s why the medication didn’t work; it wasn’t used for the entire treatment time!

“Another concern regarding indiscriminate use of antibiotics in small animals” states Papich, “is the resistance problem. When animals are exposed to antibiotics, there is a good chance that the endogenous population of bacteria will mutate or acquire resistance factors that may change them from being susceptible to being resistant. When these bacteria later on are the cause of a urinary tract infection, wound infection, or other opportunistic infection, there is a good chance that they will be resistant to standard drugs.”

Some antibiotics, such as the tetracyclines, should not be given with dairy products that contain lots of calcium because the calcium binds with the antibiotic and reduces the effectiveness. Some antibiotics, as mentioned, must be given every six hours, some every eight, some every twenty-four hours. One prescription may need to be given with food and another on an empty stomach. One group of antibiotic might cause severe diarrhea, another could permanently discolor emerging tooth enamel if given to young pups, another group could cause bone marrow suppression, and another could potentially do harm to the auditory nerve and cause permanent deafness. The moral of this story is to expect antibiotics to be used only when truly needed and then to be used according to the directions. And if your veterinarian seems reluctant to dispense an antibiotic when little Snuffy has the sniffles, now you know why. Take heart that if the sniffles turn in to something worse, antibiotics are available if needed.

Find out about this unique in-home health test kit for dogs and cats that just may revolutionize pet health care awareness!

I’ve been practicing small animal medicine and surgery for over thirty-five years and when I saw what ThePetCheckup™ can do to help detect some common pet ailments I knew immediately that this home health detection kit was long overdue. For your peace of mind and your pet’s health, I recommend this easy, accurate and inexpensive way to check at home for early indicators of pet medical problems. This in-home health test kit for dogs and cats just may revolutionize pet health care awareness. T J Dunn, DVM

Used in addition to routine veterinary care, ThePetCheckup™ helps you know when your dog or cat needs medical attention—even before symptoms appear. ThePetCheckup™ specially packages the same urinalysis test materials that are commonly used in veterinary clinics so that you can now test your animals at home (we recommend on a monthly basis) and take a more active role in their health care. Good health is the goal – but if the health screen does indicate a potential problem, you will be able to get veterinary help for your pet at an early stage—when treatment is generally less painful, less expensive, and more effective. Now there is something you can do right in your own home to help your dog or cat live a longer and healthier life!


Click on the link at the beginning of this article…
“The Internet Animal Hospital”

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  1. Pet owners should know that only fresh, quality pet medications should be used for dogs and cats and then used only as directed.

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