VetInfo Digest January 2000
If you received this issue, our computers survived the Y2K bug. All of the concern over the new century and the new millennium have made me think about how much veterinary medicine has changed over the course of time. So I thought I’d review some of the highlights of the millennium, with a strong emphasis on the highlights of the last century. Change in medicine is occurring at a faster rate now than it ever has and veterinary medicine is no exception.
I apologize for the delay in getting this issue. I really thought that I would have the time and ability to work on this issue while on vacation over the New Year’s holiday. I really enjoyed the family time this year and couldn’t get my modem to connect through the hotel’s digital phone system when there was a few minutes here and there to work. Next year, I’ll try to work on the New Year’s edition just a little bit earlier!
In This Issue:
History and Changes in Veterinary Medicine
Disease Profiles:
Parvovirus
Feline Leukemia Virus
Miracles
A Note from Michal and Me
History and Changes in Veterinary Medicine
Veterinary medicine is both a very old and very new profession. For as long as man has depended upon animals for food, transportation and companionship, there have been attempts to treat their illnesses. There is evidence of surgery on pets during the ancient Egyptian dynasties. The Romans kept dogs as house pets and there is even a mosaic at Pompeii of a dog with a leash and collar and the words "Beware of Dog". Despite that, veterinary medicine progressed very little for most of this millennium.
It would be 1852 before a veterinary college was established in the United States, although there had been veterinary colleges in Europe and other areas of the world prior to that time. Canada can lay claim to the oldest existing veterinary college in North America, Ontario Veterinary College. In the United States, Iowa State University is the oldest surviving veterinary college. It was established in 1879. The first graduate from a surviving veterinary school came from Cornell University, though. Dr. Elmer Salmon, for whom Salmonella was named, was the first person in the U.S. to receive the degree "Doctor of Veterinary Medicine". Veterinarians have been contributors to the overall knowledge in medicine, for humans and animals, right from the start.
Canada also boasts the early pioneers in small animal medicine. Prior to World War I, most of the emphasis in veterinary medicine was on horses and livestock. Dr. Duncan McEachran of Montreal, was among the first veterinarians to hospitalize and treat small animals. It would really be the early 1930s before small animal veterinary medicine really began to be accepted, though. This was the time when several major advances came to veterinary medicine, with the introduction of vaccinations for some diseases, the arrival of intravenous anesthetic agents (pentobarbital sodium), sterile surgery began to be accepted and when sulfonamids, the first successful antiseptics, became available.
Anesthesia allowed the advent of modern surgical techniques. Pentobarbital was much safer than the existing anesthetics, even though its risks are considered to be unacceptable in an anesthetic agent, today. While anesthesia is obviously a major advantage for the patient, it is far more important for the surgeon. I can just about guarantee that if patients would lay still and tolerate surgery and survive, without anesthesia, it would be fairly common for veterinarians not to use it. It is hard to imagine that, but there are still safety concerns with anesthesias in use today. They can be a true dilemma. Given the choice between anesthetics that provide better pain relief and anesthetics that patients are more likely to survive, veterinarians choose the latter group consistently. Even patients, for whom comfort during surgery is much more of an issue, might make the same choice. I am just grateful to be practicing in a time when anesthetic agents are safer and more effective than in the past. Perhaps the next millennium will witness a revolution in pain relief for patients, something that is still not emphasized enough.
In the 1950s, penicillin became available for veterinary use. It is almost impossible to overstate the impact that penicillin and the antibiotics that followed had on veterinary medical care. These medications were among the first medications to consistently work well enough to allow scientific measures of effectiveness to be established. It was suddenly possible for veterinarians to know, with reasonably certainty, that they could actually cure many diseases.
Antibiotics, when combined with effective anesthetics, allowed complicated surgical procedures to be undertaken. Prior to the advent of antibiotics it was difficult to do bone surgery or other complicated procedures without producing secondary bacterial infections. Antibiotics opened up a whole new world of surgical possibilities by making it possible to do complicated or extensive surgical procedures without much risk of complicating bacterial infections. Hip replacement surgeries, kidney transplants and other procedures that pets can have now would have much higher failure rates, and perhaps have never been attempted, without the advent of antibiotics.
Vaccinations for many of the worst veterinary viral infections, such as canine distemper and hepatitis, as well as feline panleukopenia were very effective by the early 1960s. Veterinary practitioners from this time saw huge advances in the control of these diseases. In 1978 an oddity occurred in veterinary medicine when a disease emerged, canine parvovirus, for which a vaccine already existed. Feline panleukopenia was also a parvovirus and vaccinating dogs with feline panleukopenia vaccine provided short term immunity to canine parvovirus. While this wasn’t a perfect approach, it did help many dogs avoid the initial epidemic of parvovirus in the early 1980s.
Vaccines have such strong acceptance among veterinary clients that they are easily marketed. This has produced a phenomenon in which vaccines are produced for diseases that are not very harmful. In one case, that of coronavirus vaccine, there is even some question as to whether the virus the vaccine was produced for causes any significant harm. Cornavirus vaccine has been called "A vaccine in search of a disease" by one veterinary skeptic. I can’t remember who said that first but it is a quote I have heard at a couple of seminars on infectious diseases. Many veterinarians have come to believe so strongly in the power of vaccinations and medications that we are willing to purchase them and promote their use without stopping to think about their real value. This is the down side of the medical revolution.
The success of antibiotics and vaccinations fueled the growth of the pharmaceutical industries. Research efforts to find medications that would produce similar results, both for patients and pharmaceutical company stockholders, intensified. Physicians, veterinarians and their patients or clients, demanded that medications actually work. Scientific testing of medications became the accepted standard for evaluating their effectiveness. This was an incredible advance in technology of medicine. It hasn’t totally prevented the emergence of vaccinations or medications of questionable usefulness but it has helped limit this problem.
Human beings want to believe in the effectiveness of therapies they are taking. They want to believe badly enough that it is easy to assess minor changes are important signs of a medication’s effectiveness. It is easy for observers to make "cause and effect" judgments about a patient’s progress that are invalid. Medications often get credit, or blame, for effects that have nothing to do with them. It is very hard to estimate the percentage of patients who will recover from illnesses and physical disorders without any medical intervention at all, but it would be foolish not to recognize that most will. It is also true that many patients will suffer chronic illness or die, despite expectations of full recovery on their part or on the part of their caretakers. Separating the natural recovery rate and natural complication rate from the effect of a medication requires rigorous scientific testing.
Scientific testing of medications is still an area that needs to be improved upon, though. Perhaps in the next century we will be able to develop methods of testing that can show small differences in the quality of a patient’s life during an illness or that can distinguish accurately when a medication might help or harm a small group of individuals, even when it doesn’t help or harm the majority of patients. Being able to illuminate when these sorts of effects are occurring would help to alleviate the distrust that patients whose responses to medications are out of the ordinary, in either a good or bad way, have for scientifically based medicine. Hopefully, the expectation that a product making health related claims has actually undergone testing to prove those claims will spread to the areas of nutritional supplements, herbs and other medical products or treatments. I think scientific testing will be more acceptable to these industries when it is easier to discern subtle differences in responses to therapies.
Perhaps the most important thing to think about when reviewing the progress of veterinary medicine for pets over the last century and even the last millennium is how short a time we have been gathering knowledge and making treatment plans based on scientific reasoning. When we speak of a thousand years but realize that we were still arguing the validity of sterile surgery in veterinary medicine as short a time as fifty years ago, it starts to make sense that there are huge areas of health information about which we know almost nothing, with certainty.
We know a lot about major illnesses and about how treatments affect the two big boundaries --- life and death. We just don’t know a lot about the subtle differences that make our patients feel better while they are surviving -- or dying. As we look to the next millennium, I hope that we are able to take what we have learned so far and apply it to these types of problems. Perhaps we will finally be able to help our patients experience optimum health rather than adequate health. I think that’s a good goal for the next century. Then we can figure out what to do with the rest of the next millennium!
Disease Profiles
The major emphasis of our web site has been to explain health problems in some detail. We have assumed that the major reason people come to our site and subscribe to our newsletter is a desire to have information that is more in-depth than their veterinarian has the time to provide. This has been the right way to build the site, we think, but it has ignored the needs of some people who just need an overview of diseases or health issues. Consequently, we thought it would be a good idea to try to build up a library of "disease profiles" that just hit the high points of the information available for some diseases and conditions. We’ll try to hit the diseases we get the most questions about first.
Parvovirus in Dogs
Background Facts: Parvovirus is the name of a family of viruses. There are parvoviral illnesses in many species but most of them have other names, such as panleukopenia in cats. For the most part, when you hear the terms "parvo" and "parvovirus" the reference is to this disease in dogs.
Parvoviruses attack rapidly dividing cells preferentially. In most cases, the only cells in the body which are replaced frequently enough to be attacked are the cells lining the intestine. In very young puppies the heart muscle is also susceptible. In dogs less than one year of age the entire cellular lining the intestine is replaced every five days or so. In older dogs, only the tip of the villi in the intestines are replaced, at about the same rate. So parvovirus is a disease that is clinically severe in puppies but may be an inapparent illness in an older dog.
Cause: canine parvovirus
Infectivity: Spread through contact with the stool of infected puppies or dogs. Parvovirus can live in the environment for several weeks to months. Avoid areas in which many dogs defecate when walking puppies
Age/Sex/Breed Differences: Clinical illness is almost always confined to dogs less than 14 months of age. Beagles, rottweilers and doberman pinschers may be more susceptible than other breeds.
Symptoms: Depression is usually the first sign of this illness. This is followed shortly by severe diarrhea and often vomiting. The diarrhea usually contains digested or partially digested blood giving it a pungent odor. Affected puppies often have very low white blood cell counts. Severe dehydration can occur rapidly with this illness.
Diagnosis: There are accurate tests for this virus in stool but there can be false positive results in recently vaccinated puppies, which is the case for most puppies in this age range. Depression, diarrhea and low white blood cell counts in a puppy are reason enough to treat as if parvovirus is present.
Treatment: Intravenous fluid therapy is the mainstay of treatment for this illness. Administration of serum and newer colloidal fluids along with traditional fluid therapy seems to help puppies survive. Antibiotics are necessary to prevent secondary bacterial illnesses. Since Clostridium species bacteria are a common secondary problem, amoxicillin and antibiotics with similar spectrum are often used.
Prognosis: Untreated puppies have an 80% fatality rate. In treated puppies the fatality rate hovers around 20% but seems to be improving with the use of colloidal fluids.
Prevention: Vaccinations remain the mainstay of prevention. Parvovirus is still capable of causing infection for several days prior to the time the vaccines can work to protect against the disease, though. For this reason, it is best to avoid areas that might be contaminated with parvovirus until after the puppy has received a vaccination at twelve weeks of age or older. It is recommended that vaccination start at 6 weeks of age and that puppies receive vaccinations at two to four week intervals until they are 12 to 16 weeks of age. We prefer to vaccinate at 6, 9 and 12 weeks for this virus but puppies with high exposure potential may have to be vaccinated more often.
Feline Leukemia Virus (FeLV)
Cause: Feline leukemia virus is a member of the retrovirus family.
Infectivity: Infection requires direct contact with an infected cat. Natural immunity is strong after about a year to eighteen months of age, so the current thinking is that most cats are infected prior to these age unless they are immune compromised when exposed to an infected cat.
Age/Sex/Breed Differences: The signs of FeLV may show up at any age, even though infection seems to be confined to young cats. The majority of cats showing clinical signs of FeLV are between two and five years of age, though.
Symptoms: Feline leukemia virus suppresses the immune system which allows secondary illnesses to occur. For this reason, FeLV has to be considered in almost any seriously ill cat as a possible contributor to the illness. Symptoms commonly associated specifically with FeLV include anemia, weakness, depression, jaundice and weight loss.
Diagnosis: Feline leukemia virus can be directly tested for in blood, saliva and tears. The test detects cats in the early stages of infections and cats who are carriers of the disease. Unfortunately, it has become apparent over the last few years that many cats with FeLV can keep the virus out of their circulation, making it very difficult to be sure that a cat is not infected. While the virus is suppressed successfully by the cat it will not cause illness but it may cause problems later if the cat is immune compromised for any reason. Consequently, it is necessary to test for this virus when a cat is severely ill, even it has had previous negative tests for the virus.
Treatment: There is no treatment for FeLV that will eliminate the virus. Treatments are currently aimed at supporting the immune system and keeping secondary illnesses under control by vigilant monitoring of the cat and aggressive care for any illnesses that do occur.
Prognosis: It seems likely that many cats infected with the feline leukemia virus live out normal life spans due to the ability to successfully suppress the virus. Some cats may even totally eliminate it from their body. However, many cats become long term carriers of the illness and eventually die after several months to several years. If a cat consistently tests positive for the virus in the blood stream it is unlikely that it will live more than three to five years.
Prevention: Cats that are carriers of FeLV should be kept separate from all non-infected cats. The vaccinations for this disease are effective enough that kittens who will be exposed to other cats should be vaccinated according to the manufacturer’s guidelines while kittens and then receive a booster a year after the last vaccination as a kitten. After that time, vaccination interval should be determined based on the relative risk to the cat for this disease, with every three year boosters being sufficient for most cats, probably. The feline leukemia vaccinations have been implicated in vaccine related cancers in cats, so it is important to carefully assess the risk of this vaccine as well as its potential benefits.
Miracles Still Occur
I can understand why veterinarians sometimes give up on science and begin to practice forms of medicine that are more faith based. Just about every veterinarian sees a case now and then which simply defies logic. There are times when we treat cases exactly according to the recommended guidelines, get lab results and exam findings that match a disease, treat it appropriately -- and the treatment fails. There are other times when everything that can go wrong does go wrong and a pet receives inappropriate treatment for several days but manages to recover anyway. Some pets just seem to be extraordinarily lucky and others to have incredible bad luck.
These are the cases that make it easy to think that what we do doesn’t matter or that there must be some better way to practice. I believe strongly in a scientific approach to medicine, but I thought I’d relate some of the cases that have made me wonder if there aren’t a few problems that just fall outside the bounds of science.
Early in my career I was working on a lame racehorse. I had no clue why this horse was lame. I had X-rays of every joint in the affected leg. I had removed the shoe and looked carefully for injuries to the hoof. I had done nerve blocks to see if there was pain in any particular area that could be localized by making it go away with local anesthetic. The horse continued to be lame. As I was working on him on my second or third visit, poking and prodding and sticking him with needles, he got more and more agitated. Finally, he went to strike at me with the lame leg. I had a pickax handle with a loop of string through it that we used as a twitch to distract horses while we worked on them, in my hand. In self defense, I blocked his kick with the pickax handle and he struck it hard with his cannon bone. Then he trotted off, perfectly sound. He was not lame again during the time I worked on horses.
I called all the equine specialists that I knew to ask how it could be that hitting the horse hard on its shin could cure a persistent lameness. No one knew. But one of the vets said to me, "Don’t tell anyone in the barn this worked or every trainer with a lame horse in the whole area will be whacking their cannon bones with baseball bats!" I thought about that and decided it might be true. I did not discuss this miracle cure with any of the horse trainers for quite some time.
There was a time, also somewhat early in my career, when I would try to fix almost any fracture or suture almost any wound, no matter how unlikely it seemed that there might be a successful outcome. Over time, it became painfully obvious that this approach was not helping as many patients as it was hurting and I became much more judicious about how and when I would do surgery on injured pets. However, there were some startling successes in the midst of the disappointments. One of these was a cat named Tug.
Tug arrived at our office about 7 AM on a Saturday. He had been awakened, apparently, by the sound of the car engine he was sleeping on starting up. His unsuccessful effort to get out of the engine compartment had produced numerous injuries that appeared to be a combination of direct blows from the fan and wear and tear on his skin from the fan belt. To this day, Tug is the patient who holds the record at our office for the longest surgical procedure. It took until 3:30 in the afternoon to finally figure out where each piece of skin was supposed to be and to suture it all back in place. The fact that Tug made it through his ordeal and that we got almost all his skin put back in place was tremendous luck in its own right. But that wasn’t the most amazing thing about Tug’s recovery.
As I was examining Tug’s right front leg and trying to decide how to repair it, I noticed that the large nerve that courses over the bone on the outside of the upper arm, near his elbow, was exposed. This is the nerve that when banged produces the painful effect we call "hitting your funny bone". I followed the nerve’s path and found that it was severed. I happened to have some very small suture material that a nurse had given us because the local hospital was going to throw it out. I had younger eyes and a magnifying head loupe. So I carefully sutured the cut ends of the nerve back together. I didn’t expect it to work, having been informed in veterinary school that suturing nerves when they are accidentally transacted is pretty much a waste of time.
The next day, Tug could not walk on the right front leg but he was alive, even though he did look a bit like we had had put him together with scraps of cat we had lying around the hospital. He had a great attitude and seemed like he would do well. So we sent him home. I explained to his owner that the weakness in his right front leg was due to the nerve damage and that I really didn’t expect Tug to recover from it.
We saw Tug almost every day for a couple of weeks, cleaning wounds where the sutures didn’t hold and finally taking the sutures out of the ones that did hold. Tug was a Siamese cat with a square body and a big head. Like most wounds on Siamese cats, the areas we sutured caused the hair to grow in dark, the normal color of the tips of his ears and his feet. He really looked like a patchwork quilt now, with dark lines zigzagging across his entire body. And strangely, he was starting to walk on the right front leg.
I checked him again in a month. He was using the right leg almost as well as the left by then. Over time, he made a full recovery, except that he always had the outlines of just about every injury visibly mapped in dark brown hair against the lighter tan color that made up the rest of his hair coat. I tried suturing a lot of nerves after Tug. So far, he is my only major success.
The other patient of ours that we consider to rank among the miracle cures we didn’t really treat -- at least not for the miracle. Charlie is a big beagle who would have been a hunting dog except that he didn’t like to sleep in the pen and persisted in howling all night long enough to become the sole house pet of an avid hunter.
We first saw Charlie in the middle of a busy morning in the clinic. His owner burst through our clinic door carrying his limp body in his arms.
"My dog has been at the emergency vet all night and he seemed OK when I picked him up but now he looks dead," Mr. Abbott yelled as he came through the door. My receptionist took one look and agreed with Mr. Abbott but shuttled him back to our surgery room quickly, so that he could be examined and treated immediately, if necessary.
Charlie had so much facial and pharyngeal swelling from a dog bite wound that his airway was completely blocked and he had passed out from the lack of oxygen just as he had arrived at our clinic with his owner. He had apparently been able to get enough oxygen in the emergency clinic’s oxygen cage but not enough to function in normal air.
Just the day before I had received two new trocar catheters meant to be used to quickly place chest drains in emergencies. I had been to a continuing education seminar at which the speaker had highly praised these particular catheters and so I had ordered them. They were laying on our surgical supply cabinet, waiting for me to find a spot for them. I grabbed one and pushed the trocar right through Charlie’s skin and into his trachea. Immediately we began to breath for him and to do external cardiac massage (CPR). He responded quickly and we were able to resolve his problems over the next day or so.
That seemed a lot like a miracle to us. We had the right equipment, at the right time, to save Charlie’s life. But in the process of figuring out what to do with his injuries we had taken X-rays of his neck. When I looked at the X-rays the first time, I just couldn’t believe what I was seeing. I felt like the doctor in the movie "Death Becomes Her" who is faced with Meryl Streep’s obvious broken neck and no good explanation for why she is sitting up and talking to him. Charlie had such a wide separation between two vertebrae that it was very hard to believe his spinal cord could be intact. Yet this wasn’t even what we were treating and he showed no signs of paralysis or even weakness.
I asked Mr. Abbott if Charlie had ever been injured. "You know, Doc, he was hit by a car when he was a puppy. He had a broken right front leg. The doctors fixed it but it took a really long time for him to try to get up and walk on it. They kept telling me that he should be able to, that the fracture wasn’t all that bad.".
The only explanation we could come up with was that Charlie had a broken neck that was never diagnosed when he was hit by the car. He made a startling recovery, without any assist from modern medicine. He continues to walk around normally today, eight years later. I have taken three sets of X-rays of Charlie’s neck because we have had to refer him to an orthopedic surgeon and a cardiologist for later problems. Strangely, every time I send his X-rays to anyone, I don’t get them back. I am pretty sure that there are other people besides me who take his X-rays out and look at them, every once in a while, when we think we might no longer believe in miracles.
A Note From Michal and Me
Michal and I want to wish you a Happy New Year and a great start to a new century and new millennium.
We recently passed the four hundred subscriber mark. Your support is the sole reason that the web site still exists and that the VetInfo Digest continues to be published. We had just about decided that the whole venture was too costly when we took a chance on people helping us to do a good thing and decided to see if subscriptions could support our effort. We hope that you are pleased that you are helping to make the information on our website available to others.
If you don’t want your first name to appear on posted replies on the website, or if you want an answer to remain totally confidential, just let us know. We will do our best to comply with your wishes. We will continue our policy of keeping our mailing list and contact information private. We have been approached by another web service with an offer to merge. If this happens, we will continue to protect your privacy as part of any merger plans.
It has been exciting to be part of the advances in veterinary medicine and communications technology over the last few years. We are looking forward to even better changes as we enter the 21st century.
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The opinions expressed in this newsletter are those of Michael Richards, DVM., author.
This page was last edited 06/15/04
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