Features March 2004 Issue

The Dangers of Antibiotic Misuse for Dogs

Threats from antibiotic overuse include drug-resistant “super bugs” and loss of natural protectors.

[Updated July 19, 2017]


- Reserve antibiotic use for those very rare occasions when they are necessary to save a life.

- If you absolutely must use an antibiotic, use it at the prescribed dosage and for the entire period of time recommended by the manufacturer.

- When feasible, use immune-enhancing and antioxidant supplements in place of (or to prevent the need for) antibiotics.

- Give your dog probiotics during and after antibiotic use to restore and promote healthy bacterial flora.

- Avoid using antibiotic-laden household cleansers; these help create resistant bacteria.

I’ve been fortunate enough to have lived through an era of one of medicine’s most dramatic miracles. Unfortunately, I may also live long enough to witness the miracle come full circle. Unless we get a firm grip on the two-headed monster of antibiotics, I’m scared we may be in for a self-induced era of monstrously killer “bugs,” powerful infectious agents that will actually be able to feast on any of the manmade antibiotics we toss their way.

Actually, we are almost there now. Our refusal to listen to the very people who developed antibiotics some six decades ago; our quest for the quick-fix, silver-bullet answer to all diseases; our human hubris, thinking that we are smarter than nature; and perhaps some of the very assumptions that have been the mainstay of Western medicine (e.g., the belief in the germ theory of disease, and the “us against them” model of medicine where we “confront the enemies as if we were at war with them”) – all of these have played an active part in helping to create a world where most species of bacteria are now able to develop resistance to most, if not all, the antibiotics we are able to manufacture.

Antibiotic Misuse and Your Dog

Antibiotics are one of the most useful and powerful tools that veterinarians have at their disposal for treating our dogs. However, the decision to use the drugs should not be made lightly.

And, despite what some may try to tell you (typically, those who have a vested interest in the commercial production or distribution of antibiotics are the loudest drumbeaters for the drugs), there is absolutely no evidence that we will ever be able to stem the tide of resistant bacteria . . . no matter what technology we are able to develop in the future. It turns out that bacteria are smarter than anything we have been able to develop to date – smarter than anything we have yet been able to conceive!

Furthermore, and perhaps worst of all, as we have tried to create an environment where we and our pets will never get sick, we have in fact created an environment that may be less healthy overall, and may actually be more harmful to future generations.

On the up side of all this is the hope that we animals can still create and perpetuate a harmonious environment with nature by using the natural methods of health and healing – herbal medicines, acupuncture, homeopathy, etc. Along with this use of natural medicines, perhaps we can also learn the lesson of the importance of living with nature; as we live today, it is a life-threatening certainty that the model of trying to dominate nature isn’t working.

There are at least four areas of concern when we use antibiotics:

1. Resistant strains of bacteria that will make future treatments for this patient difficult, if not impossible;

2. Resistant strains in the environment that may create super strains of bacteria that could affect entire communities;

3. Destruction of the normal flora that lives on us all and that is actually beneficial; and,

4. Adverse side effects.

Resistant Bacteria Strains

Here’s what’s been happening on the “germ warfront” while you and I were apparently asleep at the wheel:

The original production of a class of synthetic biochemicals that eventually became known as antibiotics began in the early 1940s, so we animals and our environment have had only a few decades to test the short- and long-term effects of synthetic antibiotic use. Already it is apparent the experiment has gone awry.

By one account, in 1946, just a few years after the introduction of penicillin, 14 percent of the bacterial strains isolated from sick patients were already resistant. By the end of that decade, the frequency had jumped to 59 percent in the same hospital. Today almost all species of bacteria have developed resistant strains; many species have strains that are at least 70-80 percent resistant to one or more antibiotics; and some bacterial strains are almost 100 percent resistant to nearly all the antibiotics currently available.

Interestingly, even back in the early days of antibiotic discovery, while they were being touted by some enthusiasts as absolutely miraculous, silver-bullet germ killers, the very people who were instrumental in their development were warning us about their potentially harmful aspects. These early scientists, including Louis Pasteur, Alexander Fleming, and Rene J. Dubos, all understood that there were shortcomings to the antibiotics as medicine, and they warned us of dire consequences if we did not understand the naturally adaptive mechanism of evolution that the “bugs” would use against us and our antibiotics.

The dire predictions of the early scientists were well-founded. The basic “job” of a species of bacteria, as with any species, is to survive and reproduce. Whenever a colony of bacteria is confronted with a potentially lethal mechanism (in this case, synthetic antibiotics), one of its natural survival mechanisms is to evolve ways to protect itself from the invader.

Bacteria, with their extremely rapid reproduction rate, are uniquely adapted to use evolution as a survival mechanism. No synthetic antibiotic yet produced has been able to kill 100 percent of the pathogenic bacteria it is meant to kill (without also killing the patient). Given the fact that just one surviving bacterium can produce an entirely new, antibiotic-resistant generation within days, it only takes an extremely small percentage of survivors to regenerate a new subspecies of resistant bacteria.

But bacteria are even “smarter” than this, and they have “learned” how to develop even more insidious methods of avoiding the killing powers of antibiotics. Bacteria contain plasmids – mini-chromosomes that can carry genetic information about methods of avoiding antibiotics from one generation to another in what we think of as the normal evolutionary manner.

With bacteria, however, the scenario goes beyond simple evolution. A bacteria’s plasmids can transfer antibiotic resistance information from one species to another (say, from streptococcus to staphylococcus), and the plasmid can transfer resistance information about more than one antibiotic at a time. So, if one streptococcal strain survives an insult from several different antibiotics (say, penicillin, ampicillin, lincomycin, tetracycline, and cephalexin) and thereby “learns” how to resist each of these antibiotics, this streptococcal strain can transfer this multiple antibiotic resistance “know-how” to its offspring and to other, entirely different species of bacteria.

There’s more. Recently, scientists have discovered that many bacteria have the ability to somehow predict the mechanism of destruction the next antibiotic we produce will use – and they are not only able to form resistance to antibiotic pressures they have never been exposed to, but also can transfer this ability to other species of bacteria.

It’s no wonder that experts in the field of antibiotics have been worried, from the time when the drugs were developed to now.

To be sure, it is true that many of the resistant strains of bacteria likely have been created by inappropriate use of the antibiotics. Whenever a patient does not use the full antibiotic dosage or does not continue the dosage throughout the full time-frame recommended by the manufacturer, more bacteria will be left alive to evolve ways to avoid the antibiotic pressure. However, even given perfect compliance with antibiotic dosage amounts and length of time, there will always be some bugs that aren’t killed, and some of these bugs will ultimately learn how to resist the antibiotics being prescribed to kill them.

Resistant Strains in the Environment

In 1942 the total amount of antibiotic available in the entire world amounted to about 32 liters of penicillin. Today some 20 million pounds of antibiotics are used annually in this country alone. As we’ve seen, every time an antibiotic is used, it creates an environment where bacteria are “encouraged” to evolve protective mechanisms, and the result is that our environment has become literally saturated with resistant strains of bacteria.

Much of the total amount of antibiotics produced in this country (some estimates indicate more than 80 percent of total production) is fed to food animals at sub-therapeutic levels – levels that promote animal growth (and allow for cheaper meat for the consumer), but that allow for a faster production of resistant bacterial strains. It is a simple matter for these resistant strains to be passed to farmers and people living nearby. Of course, this transfer of resistance can go the other way too – from people to animals.

Antibiotic Misuse and Your Dog

It’s becoming more common for veterinarians to need to try more than one synthetic antibiotic to successfully treat some bacterial infections in their patients.

The concern doesn’t end with food animal production. Consider that perhaps 100 to 150 million dogs, cats, and other pets are ingesting antibiotics each year – each of these with the potential to cause resistant strains of bacteria. Horticulturists and farmers use antibiotics to wage war on plant bacteria, and even our waterways are contaminated with antibiotics. Then there’s the recent movement to hyper-hygiene, an attempt to remove any and all “bugs” from the household environment by coating every surface with “protective” antibiotics.

Every year we are literally dumping millions of tons of antibiotics into our living environment – each ounce of antibiotic with the potential to create yet another antibiotic-resistant strain of bacteria.

Furthermore, scientists have shown that multiresistant bacteria spread to others as a contaminant (meat contaminated with very small amounts of multiresistant salmonella, for example) has a much better chance of causing severe infection (in our example case, life-threatening diarrhea) in those people who are currently on antibiotics. In other words, ingestion of antibiotics is an important contributing factor in the increased likelihood of getting severe disease when exposed to resistant bacteria, whatever the source of the bacteria.

There may be an even deeper problem for us pet lovers. As the problem of antibiotic resistant bacteria grows, in order to reserve at least some antibiotic effectiveness for severe cases in people, there will likely be more hue and cry that we quit using them entirely for “lesser” species such as dogs and cats. Already considerable effort has been made toward banning the agricultural antibiotic use in food animals to promote growth, and that effort is certain to eventually extend to our pets.

There are a myriad of reasons – for our health, for the health of the environment, and for the future health of our pets – that we should be concerned about the overuse of antibiotics.

Spread of Antibiotic-Resistant Bacteria

In the mid-1970s after an outbreak of resistant salmonellosis in a hospital newborn nursery in Connecticut was traced to an infected calf on a nearby farm, an experiment was conducted to monitor the potential for spread of resistant bacteria from farms.

Two groups of chickens were monitored for nine months – one group was fed sub-therapeutic levels of the antibiotic oxytetracycline (much as is the current practice to enhance growth and production); the other group acted as control (no antibiotics used). Feces were examined from the chickens, from farm workers, from a farm family living about 200 feet away, and from neighboring families whose children attended the same schools.

Within 24-36 hours of feeding the oxytetracycline-laced feed to the chickens, their intestinal Escherichia coli were converted from susceptible to those that were mostly resistant to tetracycline. Over the ensuing three months, E. coli appeared that were not only resistant to tetracycline but also to ampicillin, streptomycin, and sulfonamides, even though the chickens had never been fed these drugs. In fact, no one had used these drugs on the farm at all.

Gradually, after five to six months, increased resistance appeared in the intestinal E. coli of the farm family members. By the sixth month, the E. coli were resistant to four to five different antibiotics, and this phenomenon of multiple resistance in farm inhabitants occurred even though they were not taking the tetracycline, nor were they eating the chickens.

Other experiments have shown that a similar spread of resistant bacteria can occur between many, if not all, animal species.

Destruction of Normal Flora

About 1014th (one hundred thousand billion) bacteria live on the skin and in the gut of a normal, healthy human being. This amount is about 10 times more than all the tissue cells that make up an average 150-pound person. Almost none of these bacteria ever cause harm, and many of them are not just beneficial, they are absolutely necessary to maintain a healthy inner and outer environment. For example, a healthy gut actually requires that certain bacterial species be present in adequate numbers, and many of the bacteria normally found on the skin help provide a healthy protective activity against outside invaders.

Only a very small percentage of bacteria ever become pathogenic (causing harm), and the body has many natural mechanisms to keep these pathogens from gaining a foothold. What’s more, it almost always takes some change in the normal body’s homeostatic mechanisms to allow these species to revert to unhealthy ones.

If you use an antibiotic that is effective enough to kill most of the pathogenic bacteria, you have not only instigated the process of creating resistant bugs, but also set off the reaction that can kill many of the beneficial bugs in and on the body. The most common symptom you’ll see from the kill-off of the beneficial bacterial species is diarrhea, the result of destroying the normally protective flora of the gut. However, many medical scientists now speculate that a loss of the normal flora of the body may ultimately lead to chronic conditions such as immune-mediated diseases and cancers.

Adverse Side Effects of Antibiotics

If we think only of the extent of the direct problem, adverse side effects may be one of the least of our antibiotic-related concerns. But, in a perverse way, this habit of Western medicine to rely on statistical numbers may be a prime contributor to the overall problem.

Even though life-threatening reactions to antibiotics (anaphylactic reactions) occur only rarely, they do occur. And the fact that they are rare is certainly no solace to that one-in-several-hundred-thousand patient who has just become a statistic.

Other side effects are much more common, although they typically affect only a small percentage of the patients being treated. Some antibiotics may be, depending on the individual’s sensitivity to the drug being used, toxic enough to destroy one or more of the patient’s organ systems. More commonly, side effects are said to be “mild” and they are generally thought to be reversible when treatment is discontinued.

To my way of thinking, it is this “hidden” aspect of antibiotic adverse reactions that is as dangerous, if not more dangerous, than the actual reactions themselves. (See “Hidden Dangers of Antibiotics.”) Because they are “hidden” and so rarely observed, adverse side effects are often totally discounted. As a result, treatments (often inappropriate treatments) are instigated without even considering adverse side effects.

Worse yet: Because we veterinarians have typically been so cavalier in our approach to antibiotics, it has been easy for us to use them in inappropriate ways. Over the years it has become common practice for many of us to prescribe antibiotics to treat disease-causing agents that are not affected by antibiotics (viral diseases, for example). Also, we often have used antibiotics as a means to cover for less-than-sterile surgery techniques. And this is to say nothing about those of us who have recommended low levels of antibiotics to enhance growth in food animals. Because each of these practices allows more resistant strains of bacteria to emerge, all of them have helped create the tremendous numbers of resistant bacteria in the world today.

Hidden Dangers of Antibiotics

An illustrative true story: I once had a veterinarian call me, mad as a wet hen. “What the hell is this stuff you recommended for Ms. Smith’s dog?” he demanded in a huff. “I don’t recognize any of what you wrote down. I’m guessing they’re all some kind of herbal crapola or something like that. Is that right?”

“What seems to be the problem?” I asked, trying to remain calm, and he responded that whatever it was I had recommended, according to the lab results he had just received, was destroying the dog’s kidney.

So, I reviewed what I had recommended and didn’t recognize any of the herbs on my list as potentially nephro-toxic. I relayed that information to the doctor, and I also gave my usual disclaimer: “You know that any medicine may cause adverse reactions in certain individuals, so I suppose that what we could be dealing with here is an individual sensitivity to one or more of the herbs I’d recommended.”

Then I asked, “Out of curiosity, are you treating this patient with any Western medicine?”

“Hell, yes!” he replied. “This dog is sick, really sick. I’ve had him on gentamicin for better than a week now.”

Gentamicin, along with other aminoglycoside antibiotics, is well-known as being toxic to the kidney (as well as being toxic to ears and creating neuromuscular problems); gentamicin can cause acute cell death to the kidney’s tubular epithelial cells. Read the package insert and this is spelled out loud and clear. So, I calmly asked my irate caller, “Tell me, doctor, have you ever heard of the potential for causing renal problems from using gentamicin?” Upon which he hung up.

Read the package insert of any antibiotic and you’ll see that a certain percentage of all patients using it will have some sort of adverse reaction. Common side effects, depending on the antibiotic being used, might include: diarrhea, skin rash, joint pain, headaches, behavioral changes, abnormal bone or tooth growth, or, as in the case of gentamicin, ear, kidney, and neuromuscular toxicosis.

(Incidentally, just because adverse side effects are listed on the package inserts of antibiotics, don’t expect that your veterinarian has read them. A recent survey of physicians indicated that only a very small percentage of those surveyed had read any package insert during the past 12 months. Instead, they relied on drug company representatives to provide them with information pertinent to the drugs they bought. A similar survey is not available for vets, but I’d expect the results to be similar.)

Usually, adverse symptoms are passed off as being mild or reversible when treatment is discontinued, and because they are usually rare, the fact that they even exist is simply ignored. Then, because we practitioners ignore the possibility of side effects, we tend to feel it’s safe to use them, even when they might not be indicated. With a false sense of security, we blithely go about our business, prescribing antibiotics willy-nilly.

Don’t Create Resistant Bacteria

There are several general things you can do to help avoid the creation of resistant bacteria in your household:

• Synthetic antibiotics can be life savers – life savers that can have dire consequences if used inappropriately. Reserve their use for those rare occasions when they are absolutely necessary to save a life.

• Not all symptoms are bad. Fever, for example, is one method the healthy dog uses to overcome bacterial infections. Resist using antibiotics for every little ailment that comes along life’s pathway.

• If you absolutely must use antibiotics, use them at the recommended dosage and for the entire period of time recommended by the manufacturer.

• Avoid the routine use of antibiotic-laden household cleansers that can only perpetuate the creation of resistant bugs. Let your dogs (and your family!) develop their own immunity to the naturally occurring bacteria in the environment by interacting naturally with them. Bathe your dogs only when absolutely necessary.

Support Your Dog’s Defenses

In addition to reduced and more thoughtful use of antibiotics, there are several natural methods we can use to maintain our dogs’ health and to treat any disease that may arise:

• Probiotics (which literally means “for life,” as compared to antibiotics, which means “against life”) help your dogs maintain a healthy bacterial flora. These beneficial, “good-guy” bacteria are found in the gut in enormous numbers, with smaller numbers occurring in other locations on the body – the vagina, mouth, and skin, as examples. Probiotic species include several species of Bifidobacterium and Lacto-bacillus.

Antibiotic Misuse and Your Dog

Dog owners should give their dogs probiotics during and after use of synthetic antibiotics.

Probiotics have a number of healthful functions including enhancing digestive functions; maintaining control over potentially hostile yeasts and pathogenic bacteria; helping to maintain normal levels of certain hormones; helping to decrease cholesterol; and acting as anti-tumor agents. Perhaps their most vital activity, though, is their ability to destroy bacteria by producing natural antibiotic products.

Probiotics are easily killed by synthetic antibiotics, and returning them to their natural habitat is essential for the long-term health of any animal that is or has been on antibiotic therapy.

The ideal way to recharge the gut with healthy bugs is to supplement with a probiotic product that contains one or more of the abovementioned species. A dollop of unsweetened natural yogurt on top of your dog’s daily meal will go a long way toward helping him maintain intestinal health. If you are dealing with a specific disease, though, you may need to check with your holistic vet for the appropriate probiotics to use.

• Immune-enhancing and antioxidant supplements can sometimes be used in place of (or to prevent the need for) antibiotics. As the body defends itself against bacteria and the polluting toxins from the environment, cells form oxidative products or free radicals that are toxic to inner tissues. Antioxidants counter these toxic byproducts and in turn enhance the ability of the immune system to function properly. Several nutrients, including vitamins A, C, E, selenium, and zinc, act as antioxidants.

Herbal antioxidants include almost all the spice herbs, such as basil (Ocimum basilicum), oregano (Origanum vulgare), thyme (Thymus vulgaris), and cayenne, (Capsicum annuum), along with many others. Herbals that have a direct effect on the immune system include astragalus (Astragalus membranaceous), echinacea (Echinacea spp.), calendula (Calendula officinalis), and thuja (Thuja occidentalis).

You can provide these as a supplement to the diet on a daily or weekly basis, and the beautiful aspect of herbs is that they can often simply be added to the diet as a tasty sprinkle atop your dog’s food. Do a taste test to see which herbs he likes the best; it’s these herbs that are likely to be the ones he needs the most. Herbs and nutritional supplements can also be given at therapeutic levels whenever an infection arises. Check with your holistic vet for dosages.

• Few people are aware that there are many herbs that offer antibiotic action without concomitant risk of resistance. Within many herbs lies an almost complete medicine chest of substances that are active against a wide variety of microorganisms. There are two keys here: 1) a typical herb contains dozens of bioactive ingredients, and 2) these bioactive ingredients have activity against many different microorganisms, including the viruses where synthetic antibiotics are totally ineffective.

From a practical standpoint, this means it is extremely difficult for any one bacterial species to develop resistance to all the different bioactive mechanisms contained in a single herb plant. Also, the herb will likely be effective against a variety of micro-organisms – another bonus when we worry about creating antibiotic resistance.

On the other hand, herbal medicines do not contain gargantuan amounts of any one bioactive substance, so their effects are often mild and relatively slow-acting. This fact tempts some makers of herbal products to extract and concentrate the bioactive substances that they believe contribute the most to the herb’s beneficial action. But remember: If we remove one of the active ingredients of an individual herb and attempt to use the extract against a specific bacteria, we have returned to the basic paradigms of Western medicine that have gotten us into trouble with synthetic antibiotics.

I strongly feel that it’s best to use whole herbs. They may be generally mild and tend to work slowly, but due to their basic makeup, whole herbs are active against many microorganisms at once, making it extremely difficult for any bacterial species to become resistant.

Some of the common herbs with active antibiotic activity include: aloe (Aloe vera); calendula (Calendula officinalis); echinacea (Echinacea spp.); garlic (Allium sativum); goldenseal (Hydrastis canadensis); lavender (Lavendula officinalis); licorice (Glycyrrhiza glabra); oregano (Origanum vulgare); peppermint (Mentha piperita); sage (Salvia officinalis); and thyme (Thymus vulgaris).

• Many of the alternative medicines, including homeopathy, acupuncture, chiropractic, etc., work by restoring whole mind/body/spirit balance, and it is this restoration that allows the physical body to create an inner environment inhospitable to pathogenic bacteria.

Homeopathy is said to act by enhancing the patient’s “vital force.” Acupuncture is supposed to balance whole-body “chi.” By aligning the spine, chiropractic enhances the body’s “innate” ability to return to homeostasis. While none of these methods is specific for “fighting” germs, perhaps this is their real saving grace as medicines; while helping the patient return to normal health, none of these methods destroys beneficial bacteria, nor do any of them force the bacteria to develop resistance.

Antibiotic Summary

I am personally scared to death that antibiotic use may become the single most formidable opponent to health we have ever seen in human history. I pattern my fears after many other medical scientists, from those who “discovered” antibiotics to today’s more enlightened scientists and practitioners; see the bibliography below for a partial list. If I didn’t succeed in scaring you, I hope you will at least think long and hard before you let your veterinarian use or prescribe antibiotics for your dog.

There are lots of natural ways to prevent and combat infections. We have used some of these methods for millennia; neither our species nor those of our animal companions were on the brink of extinction before we discovered antibiotics! Some infection-fighting methods use substances that already occur in nature, and the best do no harm to the powerfully healing environment all of us living creatures rely on.

Also With This Article
"Selected Bibliography."

Dr. Randy Kidd earned his DVM degree from Ohio State University and his Ph.D. in Pathology/Clinical Pathology from Kansas State University. A past president of the American Holistic Veterinary Medical Association, he’s author of Dr. Kidd’s Guide to Herbal Dog Care and Dr. Kidd’s Guide to Herbal Cat Care (see "Resources").

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