VetInfo Digest

VetInfo Digest October 2006

Table of Contents:

What is good medicine?

This month’s note:

Many of you had questions about Henry, my Cavalier King Charles Spaniel puppy after last month’s note. Henry is doing pretty well but he does have clinical signs of heart disease so we have made the decision to attempt to have his heart repaired. He has pulmonic stenosis, which is narrowing of the valve between his heart and lungs. It is possible to pass a balloon catheter through is femoral artery and circulatory system into this valve, where it is quickly and repeatedly inflated to increase the diameter of the valve. The surgery is supposed to be successful about 80% of the time. He is scheduled for surgery in mid-October so I will fill you all in on the results next month.

Good Medicine?

A client came into our practice last month and asked for his pet’s records in order to seek homeopathic treatment for heartworm disease. I can tell you with near certainty that homeopathic treatment of heartworm disease doesn’t work. I know this for several reasons. I have followed the care of several dogs treated with homeopathic remedies for heartworm disease and done follow-up testing on them over a number of years. On each subsequent visit occult heartworm testing was still positive, despite the therapy. Despite this, the owners were convinced that the treatment had been successful.

I can also tell you that some conventional vets treat heartworms ineffectively, using conventional medications, because I have followed the results of their treatment efforts over time, as well. The owners of these dogs are equally likely to point out that I am wrong about the continuing heartworm disease symptoms and test results because they know they have treated the dog.

Finally, I can tell you that if you do absolutely nothing about heartworm disease, some patients will self-cure. I know this because I have followed a number of these patients over the years, too. The owners of these pets are sometimes convinced that all they have heard about heartworm disease is hype from veterinarians wishing to make money by treating their pets unnecessarily.

So what is the meaning of these things when viewed together?

There is good medical practice and bad medical practice. This statement applies to any type of practice philosophy. It is entirely possible to practice good medicine with an underlying philosophy favoring homeopathy, favoring herbalism, favoring pharmaceutically based practice or favoring a holistic approach that includes elements of several medical practice philosophies.

It doesn’t really matter what underlying philosophy of practice your veterinarian or medical advisor chooses as a base. What matters is doing what is best for the patient, considering as many risk factors and potential benefits as possible and trying to put together a plan that maximizes the chance of getting the benefits while minimizing the risks taken. Doing this requires a great deal of empathy for the patient and client, as well as taking the time to think through the possibilities. It also requires some measurement over time of the results of the choices made. If this last step is not taken seriously it is entirely possible to make patients worse for a very long time without realizing it. It is also possible in some cases to see benefits that weren’t anticipated and would go unnoticed without some measurement of the effect of medications.

Testing or assessing the results of treatment should be a part of every medical procedure. In addition, some early recognition of what the expected results of treatment are should be established. It is possible to do a very good job treating epilepsy without reducing seizure activity completely. If a dog is seizuring several times a week and the seizures are reduced to once a month, a neurologist would likely consider this to be a good outcome. A pet owner might not. If you know in advance what the neurologist considers success to be you may decide it is acceptable to you or you may decide that you want to pursue some other form of therapy.

Flea control is one area in which there is a lot of room for argument over what constitutes successful therapy. I get lots of pet owners who let a flea problem build up for months and then expect instant results from any therapy. This pretty much ensures they will be disappointed. Killing adult fleas is pretty easy. Where pet owners often fail in their assessment of flea control is an unwillingness to accept certain aspects of flea biology. Adult fleas try to spend their entire remaining life on the pet. Eggs that the female flea produces fall off the pet as they are produced. The larval and pupal stages of the flea develop very close to where the eggs fall off. Therefore, if your pet has fleas, you have fleas in your house. Maybe not adult fleas but lots of flea larvae and flea pupae who will become adults soon. As they hatch, your pet is re-infested. If you fail to understand that point then the fact that you continue to see adult fleas, even if they are quickly killed by the flea control product, seems like failure. On the other hand, if you recognize that the great majority of the flea population consists of immature fleas and that there is nothing you can use that kills that pupal stage of the flea, you can see that a lower number of adult fleas will be seen for several months. As long as the number is dropping off you are working towards successful control of the problem.

It is important to assess the right things, too. In the case of heartworm disease assessing the dogs current condition is not satisfactory. Heartworms cause problems very slowly over a long period of time in most dogs. Therefore, it is important to test for the worms themselves. On the other hand, if a dog is itchy, presumably due to fleas and you use the itchiness to assess success in flea control, you are assessing the wrong way. It is entirely possible to completely control fleas and still have an itchy dog. If you continue to put major effort into flea control and ignore the fact that something else is causing the itchiness, you aren’t doing a good job for your patient.

I would be really thrilled if medicine was just a matter of logic and correct therapy. Unfortunately, there is also good luck and bad luck. I have seen lots of patients for second opinions who were not responding well to therapy, despite excellent work-ups, apparently correct diagnostic assumptions and proper treatment for those problems. This is hard to understand. Even harder to understand is how some patients do extremely well despite obvious misdiagnoses or improper care. There is always some chance that treatment is helping with an unidentified problem in these cases but most of the time I think it is just good luck.

In going back to my heartworm example, I was motivated to see what the various options in homeopathic treatment were for heartworm disease. As is usually the case I found that many of the treatments claiming to be homeopathic actually weren’t. Homeopathy is a very specific form of therapy, not a general term for “natural” or “alternative” therapies. In addition, I found that there are a number of homeopathic veterinarians who attempt treatment for heartworms using homeopathic remedies but who set a time line for success. If the patient is not cleared of heartworms based on occult heartworm testing within a certain period of time they fall back to conventional treatment. While a really dedicated homeopath might not consider this good medicine, I consider it a good approach to medical care. It is reasonable to try almost any methodology of medicine as long as there are definitions for success and alternative plans when those requirements are not met.

The dogs I have seen treated inappropriately for heartworms using conventional medication have been given a variety of dewormers, medications meant for heartworm prevention rather than treatment and various alternations of the recommended dosages or dosing intervals of the medications actually approved for heartworm prevention. I have not tried very hard to talk to the practitioners who have used these methods to try to understand their logic, with the exception of the vets who are using heartworm prevention medications in the hope of a cure. In almost every case the vets promoting these cures were also using heartworm testing methods they knew, or should have known, to be ineffective and then justifying their treatments with the results of these tests. Using appropriate test procedures it was possible to demonstrate that the dogs still had heartworms. You have to measure success using some standard that will actually measure it!

You might think that people would be grateful when you point out to them that their dog has not actually been cured of heartworm disease but that it was still possible to treat them appropriately if that is desired. In almost all cases, you would be wrong, at least based on our experience. One of the things about all potential therapies is that once people buy into them they tend to be very defensive of their decision making. This is why it is critically important to decide what you will consider to be successful therapy before starting a treatment plan and how you will evaluate the results of the treatment. I tested one dog in our practice that had been treated using a “new” technique, using three different occult heartworm test procedures, all of which were positive and the client still stormed out of our office, looked back at the door and said something like “You’re just angry you didn’t get the money for treatment!” Don’t fall into the trap of ignoring test results or continuation of symptoms just because you want a treatment to work. Know what you plan to do if treatment goals are not met within specific time periods.

I have to take a break from the natural flow of this article for a moment and explain one thing about heartworm disease as it is important to the above discussion, even though it is a side issue. There was a study done at the University of Georgia that showed that dogs given heartworm prevention medications containing ivermectin on a regular basis after heartworms were deliberately introduced into the dogs were able to clear the heartworm disease in about 18 months. This study prompted a lot of vets to give up on the conventional therapy for heartworm disease and to rely on using heartworm prevention medications to treat heartworm disease as well as controlling new infection. This study had a serious flaw that it took a little time to discern, though. The dogs were deliberately infected with young adult heartworms. It turns out that heartworm prevention medications based on invermectin do have some ability to shorten the life span of heartworms if the adults are exposed to the medication before they are 8 months to a year or so old. After that, there isn’t much effect from heartworm medications used at the regular prevention doses -- and no one has studied higher doses to the best of my knowledge. This means that in many naturally infected dogs there will be no benefit, or minimal benefit, from attempting to treat dogs with ivermectin based prevention medications because they have already got heartworms that are older than the susceptible age. Some dogs will do well, because some dogs do well with no treatment at all. Other dogs will develop clinical heartworm disease and die despite the therapy. Sadly, we are dealing with the end stages of one of these dog’s lives in our practice at this time.

There are a number of other diseases in which there are choices between conventional medications and alternative therapies or between “more toxic” and “less toxic” conventional therapies. One of these situations occurs with hyperadrenocorticism, or Cushing’s disease. There are several ways to treat Cushing’s disease. For many patients it is acceptable not to treat the disease, as long as the symptoms aren’t bothering the owners or the patient too much. One approved therapy, selegiline ( Anipryl Rx), doesn’t seem to alter any of the lab test results normally associated with Cushing’s disease. However, it often seems to reduce the symptoms enough to make veterinary clients happy. If that is the criteria for success, then that is enough. On the other hand, the two medical therapies most commonly recommended, mitotane (Lysodren Rx) and trilostane (Vetryl Rx) are more likely to cause side serious side effects but do actually have impact on cortisol levels and therapeutic success can be measured by testing procedures. For many veterinarians this is the only acceptable way to measure success since people’s impressions are prone to be altered by the placebo effect when medications are administered. Choosing the definition of success in advance is very important to any discussion of Cushing’s disease therapy. Do you just want to relieve the symptoms or do you want to control the excessive cortisol levels, as well? Just to cover all the bases, hypophysectomy, or surgical removal of pituitary tumors that cause most cases of Cushing’s disease, is also an option although there is limited availability for the surgical procedure at this time. The surgery can provide an actual cure for the disease, though, rather than a management program.

I have a few clients who seem totally convinced that pharmaceutical companies are evil to the core. They believe that pretty much all pharmaceuticals are ineffective, toxic, oversold and under regulated. Some of my clients who believe this have had genuinely bad experiences with side effects or unintended consequences of intended effects from various medications. Others just seem to be influenced by conspiracy theory and the visible profit motives of pharmaceutical companies.

I think it is a good idea to maintain a healthy suspicion of medications -- all medications, natural or manufactured. People who have something to sell are predisposed to tell you the good things about it and to ignore the bad things. There is very little question that modern medications have made a huge difference in health, on the average. There is also very little question that modern medications have ruined the health of some dogs and cats. If no consideration is given to the possibility that a medication will have or is having adverse effects then the veterinarian is not practicing medicine carefully. On the other hand, excessive fear of medications that are necessary causes a great deal of harm when those medications are withheld. Make sure that you understand the most likely side effects of a medication. Make sure that you know what beneficial effects you are looking for and approximately how long it will take to see them. If problems occur or if expected benefits are not seen within the expected time period, contact your vet.

There is one thing that I think has be mentioned when it comes to pharmaceuticals. Drug companies spend a lot of money trying to convince veterinarians and pet owners that their medication is the best one to reach for when “X” illness occurs. In general, they are pushing mostly new medications that are still under patent, because these are the medications they make the most money from. There are many times when the newest, latest, “greatest” medication isn’t necessary. For most patients the cost of a medication doesn’t correlate at all with its effectiveness.

If your vet never tells you that it may be a good idea to wait and see what happens before using medications there is a chance that he or she is using medications inappropriately, either as a profit generating mechanism or out of fear that doing nothing will disappoint you. For many patients there will be some question as to whether or not to treat with medications at all. A dog or cat with infrequent seizures may never need therapy to control the seizures. A puppy with demodectic mange has nearly a 90% chance of recovering with no treatment at all. Wounds that are quite large will heal with time, if surgery is not a good option for a particular patient or client. I think that this is one of the reasons that ineffective therapies last for years, or even centuries. If you are treating a patient who is going to get better without treatment, your therapy will look good as long as it doesn’t cause harm. Since most of our patients are going to get better no matter what we do, it is important to remember that a successful outcome isn’t a guarantee that treatment was appropriate. It just means it didn’t make things worse.

Deciding to do nothing is often the most difficult decision facing a veterinarian. After all, people come in and pay good money to get an answer to their pet’s problems. If all that the vet does is say “Give it some time.” there is a tendency to think the visit was a waste. In reality, it is good that your vet is willing to trust you to take his or her best recommendation, rather than dispensing some medication that is approved for the condition that the pet seems to have but which is not likely to help. A classic example of this is the use of Goodwinol ointment for demodectic mange. This ointment was approved a very long time ago and it is well known now that it has little, if any, effect on the Demodex mites. However, when veterinarians want to wait and see if demodecosis will improve before using therapies that might have significant side effects, there is a tendency to hand over a tub of Goodwinol ointment to apply to affected areas. It gives the anxious pet owner something to do that isn’t likely to be harmful. This is probably reasonable as long as the medications aren’t likely to cause problems on their own -- but it still shows more trust in the client to just tell them no treatment is necessary.

Small lacerations are something that we have a hard time deciding what to do for in our practice sometimes. If the goal of therapy for a wound is to obtain a minimal scar, it might be necessary to suture the wound to obtain that goal. If the goal of therapy is to eventually have closed skin and scarring is not a big deal, only really large wounds or wounds in places where healing is difficult, such as elbows, might need suturing. Over the years I have sutured fewer and fewer lacerations, until recently. I have noticed that my patients seem to feel better sooner when wounds are sutured. This has led me back to a point where I suggest suturing wounds more often than in the recent past. However, I still tend to think that it is acceptable not to suture many wounds. Now I just try harder to understand the client’s motivation. If they are mostly concerned about cost and I think a wound will heal, I don’t suture it. If they are mostly concerned with avoiding pain for the pet, I am much more likely to suture the wound. I have some clients who want to avoid causing the pet pain but also want to avoid using general anesthesia. This is no problem if the pet is calm enough to use a local anesthetic but it can be a major part of the decision making process for pets who have lacerations in places where local anesthesia won’t help due to motion or positioning or for pets who are just too nervous to allow us to work on them even when we are not causing them pain. A compromise in these cases is to allow a wound to heal on its own but to provide pain relief medications. There are often several ways to approach the treatment of a problem and all can be correct in certain circumstances.

For many aspects of veterinary care there is no way at all to know if a particular approach to diet, therapy or surgery is effective, even over time. This is enormously frustrating for veterinarians. I think that the vast majority of vets really do want their patients to benefit from therapies. There is a strong tendency to think that just because a treatment is available it should be used. Given the evidence to back up doing nothing I think that most vets would choose that option when it clearly made as much sense, though.

As I have noted in past editions of the VetInfo Digest, one of these examples is cruciate ligament surgery. This is a very common surgery but the long term results in studies have not shown much benefit to patients despite good short term outcomes. The exception to this rule might be tibial plateau leveling osteotomy (TPLO) surgery, but at this time there have not been any studies done that I am aware of that have looked at patients who have had TPLO surgery five or more years later. Until these studies are done it is not possible to know whether or not the long term results are beneficial. The short term results look very good but that is true of most stifle surgery. So is it best to have surgery when a cruciate ligament is ruptured? I would argue that right now there is no definitive answer to that question, although I know that the majority of veterinarians disagree.

There are a very large number of specialty diets available as well as a great deal of interest in dietary philosophies, such as feeding raw foods, feeding only “natural” ingredients, feeding diets that are based on regionally available ingredients for breeds that originated in known environments, among other choices. For the great majority of these diets there is simply no information available from well designed studies to support or refute the claimed benefits. This includes most of the veterinary “prescription” diets, although there is good data to support the use of the kidney disease diets, at least.

Your veterinarian is a human being and is susceptible to the influences of training, marketing, personal experience and peer pressure, just like most other human beings. There undoubtedly is a culture among veterinarians that influences practice philosophies. Some vets will dismiss anything other than the style of medicine they were trained in, offhand. Others do take the time to look into other practice philosophies and to try to sort the good from the bad in them. This can be a very daunting task.

I work with a number of clients whose basic medical philosophy is much different than mine. It doesn’t really matter to me if a client wants to try a different approach than the one I favor as long as I don’t think the pet will be harmed. In some instances I will work with clients even when I think the pet might be harmed, as long as the client truly seems to understand the potential consequences of their decisions. I really only take a firm stance against therapies other than the one I favor when I am nearly certain that the pet will be harmed by the choice. This happens far less frequently than you might imagine. In those cases, I tend to ask the client to seek care from another veterinarian who is more inclined to treat in the manner they prefer.

Mammals are very complex organisms. It is astounding to me how well all the billions and billions of cells that make up an organism work together. I am constantly surprised that people and pets aren’t continuously suffering from conflicts between body systems or failures of some small part of the system. So when pet owners are surprised by the sudden appearance of illness I am always surprised by the normal physical examinations. I also understand that just because I’m not finding something doesn’t mean that all is well. It just means that there are no obvious symptoms, today. When I use medications they are interacting with this complex organism in more ways than I can possibly be aware of. To ensure that I remain vigilant about medical complications it is necessary to work hard to keep these four things in mind:

1) Have I given the client a firm idea of what I expect to achieve by using a medication or procedure, including specific guidelines for what constitutes successful therapy in my opinion?

2) Does my opinion of success meet the client’s needs? If not, are they aware of that?

3) Does the client know when I think it is necessary to conclude that medication or therapy has not been successful, based on clinical signs or measurable results and what the next step is in that case?

4) Am I willing to recognize my limits? When a case is not responding in a way I think it should or when testing or specialized procedures might benefit the patient do I refer the pet to a specialist or another practitioner who might have a better approach?

If everyone involved fully understands these four things and the answer to each question is yes, then I think that I am practicing medicine that can be defended as good medicine - even when the outcome isn’t what I hope for. I think that this is also true for vets who practice a different type of medicine than I do, as long as they can also say “yes” to these questions. It isn’t a matter of conventional medicine being good or of any alternative medicine being good or bad, it is about whether the practitioner is good and is keeping the patient’s best interests in mind.

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The opinions expressed in this newsletter are those of Michael Richards, DVM., author.