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Why Should I Get My Cat Vaccinated?

Is Vaccination for Cats Helpful or Harmful?

Vaccination is not as widely and unquestionably accepted today as it was in the past.


Many pet guardians and veterinarians believe we have taken the concept much farther than its usefulness warrants. In twenty years of veterinary practice, I have made the transition from believing strongly in the protective power of vaccines to becoming continually more certain that they create at least as much illness as they have ever prevented. In truth, I now consider vaccination to be tantamount to animal abuse in most cases.

This opinion has two main bases: First, vaccines often do not provide any protection. This may result from poor vaccine performance (as with feline leukemia virus, feline infectious peritonitis virus, and ringworm vaccines), lack of risk (all vaccines at times, but particularly the above vaccines plus rabies), or simply lack of need (as with booster vaccination in almost all cases). Secondly, many vaccines actually induce illness that is much greater than that of the diseases that they are designed to prevent. 


A further consideration is that vaccination weakens the strength of a population by allowing individuals to survive that otherwise would succumb to natural diseases; these diseases provide cleansing and strengthening for the population under normal conditions. The population is further weakened by immunosuppressive and possibly gene-damaging vaccine impacts. Vaccination likely provides protection from acute, contagious diseases by inducing chronic disease. This trade-off is not a good one and itself amounts to abuse.


Obviously there are several issues here that affect an immunization decision. Each is a separate factor with its own issues. I’ll start with booster vaccinations, as this is the clearest area and one with little risk of error. Simply put, there is almost never a need for booster immunization. Once immunized, an animal, as with humans, is protected for life. Further vaccinations do not improve the immunity. The following quote, from Ron Schultz, Ph.D., and Tom Phillips, DVM, appeared in Current Veterinary Therapy XI in 1992 (This is a purely conventional textbook, and Drs. Schultz and Phillips are respected veterinary immunologists in the academic community):


”A practice that was started many years ago and that lacks scientific validity or verification is annual revaccinations. Almost without exception there is no immunologic requirement for annual revaccination. Immunity to viruses persists for years or for the life of the animal. Successful vaccination to most bacterial pathogens produces an immunologic memory that remains for years, allowing an animal to develop a protective anamnestic (secondary) response when exposed to virulent organisms.

Only the immune response to toxins requires boosters (e.g. tetanus toxin booster, in humans, is recommended once every 7-10 years), and no toxin vaccines are currently used for dogs and cats. Furthermore, revaccination with most viral vaccines fails to stimulate an anamnestic (secondary) response as a result of interference by existing antibody (similar to maternal antibody interference). 

The practice of annual vaccination in our opinion should be considered of questionable efficacy unless it is used as a mechanism to provide an annual physical examination or is required by law (i.e., certain states require annual revaccination for rabies).”


In essence, Drs. Schultz and Phillips are stating that the only reasons for annual vaccination are legal (as with rabies vaccination) or as a means of manipulating guardians into bringing their companions for examinations (rather than simply recommending an examination). They also clearly state that booster vaccines provide no other benefit, including improved or added immunization. 


Although it has been some years since this was published, the veterinary community has made little headway toward following these recommendations. Some university experts now recommend vaccinations every three years, and other university clinics recommend titer testing to determine need. While both concepts are a step in the right direction, they still do not reflect the actual picture. 


As the above quote indicates, immunologic memory lasts for years (usually for the life of the individual). This memory is not dependent upon titers, nor do titer levels always accurately indicate the immune status. A titer is a reflection of the quantity of circulating antibodies (immunoglobulins) to a given antigen (in this case, an organism). Cells in the body produce the antibody. These cells retain the ability to produce antibodies toward a given antigen for quite a long time, usually for life. 


Upon re-exposure, they can produce antibody within forty-eight hours. As a consequence of this capability, there is no need for the body to expend the energy needed to maintain circulating antibodies. A low or absent titer, therefore, does not mean the body is unprotected. The body may simply have cells ready to act, like firefighters playing cards until they are needed. When booster vaccines are administered, antibodies destroy the vaccine particles before they can augment the immunity, and nothing is accomplished. 


With kittens, antibodies (maternal antibody) may be passed from the mother to the kittens via the umbilical cord and via colostrum (the first milk). This antibody serves to protect the kitten, but it also can interfere with vaccination. For this reason, we often vaccinate kittens multiple times, in hopes that we will give a vaccination shortly after the maternal antibody diminishes to a level that will not interfere with vaccination. This is often overkill, as one vaccination can induce immunity in approximately 95 percent of animals if the timing is correct. 


Multiple vaccination, particularly with combination vaccines, is one of the greatest contributors to vaccine-induced illness. Limiting vaccination to one or two doses of appropriately indicated vaccines could greatly reduce disease from vaccination. In my opinion, this would be a huge step in the right direction for those who are too fearful to avoid vaccines entirely. 


The next area of concern is that of risk. Veterinarians and vaccine companies frequently use fear to convince others of the need for vaccines. Often, the risk of disease is so small that vaccination is foolish. Many cats are kept indoors, and while this practice is certainly controversial (I believe all animals need exposure to the outside), these cats have virtually no risk of exposure to most organisms (especially rabies and feline leukemia virus, both of which require direct contact with an infected animal). Vaccination is generally pointless for these animals. 


Even in outdoor cats, vaccines may be unnecessary, as many diseases are not truly contagious. In these cases vaccination is useless since it is not directed toward the cause of illness. These diseases are immune suppressive (often autoimmune) conditions. The immunosuppression occurs first, allowing a virus, bacteria, or fungus to grow. We know this because healthy animals are unaffected by these organisms. 


Organisms that fit this category include feline leukemia virus, feline infectious peritonitis virus, feline immunodeficiency virus, and ringworm (in most cases). Vaccines for these diseases are therefore of no benefit; in fact, they often induce just the disease they are purported to prevent. These vaccines are among the most dangerous ones available. The only prevention of these diseases comes from a healthy diet and lifestyle.


Vaccination often receives undue credit for disease prevention, and we often hear raving about the lifesaving benefits of vaccination. From human studies, however, we know that the death rates of measles, whooping cough, and polio had fallen significantly prior to the introduction of vaccination; in the case of measles it had dropped 95 percent. Many practitioners around the turn of the century reported that smallpox immunization often increased a person’s chance of disease; this was even reflected in public health statistics. (Miller) Most of the reduction of disease actually resulted from good food and good hygiene. 

This brings us to the question of damage from vaccines.

Although this is the most controversial aspect of vaccination, I see this so commonly that I personally have no doubts that vaccines are extremely dangerous. Most of my homeopathic colleagues are in agreement. We believe vaccination underlies a huge percentage of illness that we see today, and especially the rash of autoimmune diseases; these have increased dramatically since my graduation from veterinary school in 1979. 


I’ll briefly present a case that turned my head many years ago. When I first heard that vaccines might actually cause disease, I was skeptical. Of course, I knew about allergic reactions and other quick responses, but I assumed that these initial reactions were the extent of the problem. I remember a case, however, that opened my eyes. Fluffy was a sweet Persian cat who lived with an equally sweet woman. 


Fluffy had recurrent bouts of cystitis (urinary bladder inflammation) that were very resistant to conventional and homeopathic treatment. Despite the fact that I liked Fluffy’s guardian (and Fluffy), I hated to hear from her, as it was such a frustrating case. The bladder infections were never under control for long before they would return. One day I was reviewing the record for some clue as to what to do next when I had a stunning revelation. The cystitis bouts were always about a month after the yearly boosters. I suggested to Fluffy’s guardian that we no longer vaccinate Fluffy, and I never needed to treat Fluffy’s cystitis again. I could only conclude that vaccines could indeed cause diseases—even a supposed infection.


Once I opened my eyes to the possibility of vaccine-induced illness, I began to see it commonly. It even became clear that certain vaccines could cause chronic illness that resembled the acute disease that the vaccine was intended to prevent. Panleukopenia is a good example. 


With panleukopenia, major symptoms include inflammation and degeneration of the intestinal tract leading to severe vomiting and diarrhea, severe reduction of white blood cells (leukopenia) leading to immunosuppression, loss of appetite, mucopurulent nasal discharge, dehydration, and rapid weight loss. The chronic diseases we see frequently in cats correspond to many of these symptoms. Inflammatory bowel disease, an autoimmune inflammation of the intestines, is occurring at epidemic levels today. This disease was virtually nonexistent twenty years ago, yet today it is one of the most frequent diagnoses.


Cats are also extremely susceptible to immune malfunction and immunosuppression. The immunosuppressive state has been associated with two retroviruses (feline leukemia virus and feline immunodeficiency virus), and others are suspected. Rather than these being separate diseases, I believe they are the same, but that more than one virus can fill the niche opened by the immunosuppression (remember that with chronic diseases the illness precedes the infection). This is probably the same in people with HIV (human immunodeficiency virus) related viruses. Parvoviruses, which include the feline panleukopenia virus, are known to be very immunosuppressive. Additionally, I suspect the feline upper respiratory infections are a chronic state of the panleukopenia virus-induced immunosuppression and the tendency to get eye discharges. 


A similar scenario now exists in dogs. While immunosuppressive states are not common in dogs, reports of their occurrence are on the rise. I believe the massive vaccination program for canine parvovirus, which began some thirty plus years after we began vaccinating cats with feline parvovirus (panleukopenia virus), is creating this situation in dogs. If this is true, then the imminent future bodes poorly for dogs if the problem in cats is an indication. Furthermore, we have been seeing inflammatory bowel disease in dogs over the past five to ten years. Prior to this it was virtually nonexistent. I am certain that vaccination for parvovirus and coronavirus is a major cause. I commonly see inflammatory bowel disease that arises within a month or two after vaccination for one of these viruses. 


There is still another syndrome associated with parvoviruses, one that occurred first in cats, and later in dogs. Cardiomyopathy is a disease of the heart muscle. The muscle may either weaken and stretch (dilated cardiomyopathy), or it may thicken greatly (hypertrophic cardiomyopathy). Either condition will limit the heart’s ability to pump blood. Cardiomyopathy is often fatal. 


We have been diagnosing cardiomyopathy in cats for over twenty years, approximately the same period of time as for inflammatory bowel disease. Many (but not all) cases of the dilated form of cardiomyopathy have been associated with a deficiency of the amino acid L-taurine. The cause for hypertrophic cardiomyopathy, as well as the cause for the nontaurine-associated cases of dilated cardiomyopathy, is unknown. I believe that the answer may have appeared in dogs.


When canine parvovirus first erupted in the late 1970s, many young puppies died rapidly, sometimes within hours. It turned out that parvovirus was capable of attacking the heart muscle in young puppies, and this form of the infection killed the puppies rapidly. 


Cardiomyopathy did not affect dogs before the parvovirus outbreak (or if so it was very rare), but in the years since the outbreak it has appeared. The number of cases has especially risen over the past five to ten years, coincident with the rise of inflammatory bowel disease in dogs. The Merck Veterinary Manual states that, “The cause [of dilated cardiomyopathy in dogs] is still unknown although viral infection and resultant autoimmune reaction against the damaged myocardium are suspect…. Since the canine parvovirus (CPV) pandemic of 1978, male Doberman pinschers appear to be highly vulnerable to both CPV and cardiomyopathy.” (Fraser) In the years since this was written (in 1986), we have begun to see cardiomyopathy in many other breeds as well as Doberman pinschers.


I believe the author of this section of The Merck Veterinary Manual was correct, but I believe that parvovirus vaccination is even more likely to be the cause in most cases. I also believe that this explains the occurrence of cardiomyopathy in cats. Perhaps the heart muscle association of the feline parvovirus (panleukopenia virus) was not seen in natural infections, but vaccination brought it to the surface. Cardiomyopathy is an autoimmune disease, and vaccines are major causes of autoimmune disease. In my opinion, these connections are too close to be coincidence alone.


Another vaccine that induces great anguish for guardian and companion is the rabies vaccine. I see many cases of fear and aggression that stem from rabies vaccination. If you consider the nature of rabies, this might not surprise you. It appears we are introducing chronic rabies into our animals by injecting rabies virus particles into their bodies. How, you may wonder, could inactivated virus induce illness? Apparently, the ability to affect change is not contingent upon the quality of aliveness, as we understand the concept. In fact, viruses are on the border between living and non-living; they require another organism to reproduce and thrive; otherwise they are little more than a chemical compound with the potential to alter the metabolism of their hosts.


Other conditions we see frequently in veterinary medicine today are not so directly traceable to a particular vaccine, but the general connection to vaccination is clear to many practitioners. Hyperthyroidism (increased production of thyroid hormones) was not seen when I first graduated from veterinary school. It was not simply misdiagnosed. The symptoms are so characteristic that the syndrome would have been recognized even if the cause was unknown. The disease did not exist. 

Could vaccines be responsible?


Let’s look at another case: 
Sheba is a Siamese mix cat. She was nine years old when her guardian first consulted me. One week after vaccination, Sheba stopped eating and developed a rapid heart rate. Her conventional veterinarian suspected hyperthyroidism, although thyroid testing revealed no abnormalities. One dose of Thuja (a homeopathic remedy) reversed the rapid heartbeat and the appetite problems, and her health bloomed after the remedy so that she was better than before she became ill. Clearly the vaccines had caused these problems. I believe she would have developed true hyperthyroid disease if untreated.


The status of cats has elevated significantly since the 1960’s. Prior to this most cats received little veterinary care. Since the 1970’s, however, as cat status elevated, the care given to cats has climbed. This has generally meant more vaccinations. And rabies vaccination was often not recommended for cats until the mid-1980s. I believe the massive increase of vaccines in cats is responsible for hyperthyroidism as well as many other recently emerging diseases. 


Cats suffer greatly from vaccination damage. The most obvious vaccine-induced problem is one that is deathly serious, causing great suffering among cats and cat companions.

Fibrosarcomas, a type of cancer, occur more and more as a result of vaccination.

The vaccines that are implicated are the rabies and feline leukemia virus vaccines. These cancers arise at the site of injection of one of the vaccines. Researchers have identified vaccine particles within the cancer mass in a number of cases; the link is definite. Many veterinarians now refer to these cancers as vaccine sarcomas.


Fibrosarcomas are malignant, and the average life expectancy is less than three years once the cancer has arisen. No treatment has proven satisfactory. Even with aggressive surgical removal, these cancers recur in the vast majority of cats. Some leading veterinarians recommend giving the vaccines in a leg, or even in the tail (ow!), to make amputation a viable option in case the cancers arise. Does this make sense?


Obviously, when we reach the point of making recommendations like these, we are out of control. But do we simply avoid vaccinations in order to avoid all risk? Or is there possibly more risk by not vaccinating? Personally, I am opposed to vaccination in virtually all situations, but I will endeavor to give some guidelines that will assist you in making a balanced decision regarding your feline companions. 


There are four criteria that are at the center of any vaccine decision. One should only consider administering a vaccine if all four criteria are met:


1. The disease is serious, even life threatening. 

2. The animal is or will be exposed to the disease. 

3. The vaccine for the disease is known to be effective. 

4. The vaccine for the disease is considered safe. 


Let’s look at individual diseases to see how this works. I’ll start with feline leukemia virus (FeLV) disease. An indoor-only cat will not be exposed (number two) as this virus requires direct, intimate, cat-to-cat contact for transmission. Many veterinarians recommend immunizing indoor cats against this disease, but I feel this is unethical. This disease does not fit criteria numbers three or four anyway in my experience, so vaccination is unwarranted in most if not all circumstances. If a vaccine for the feline immunodeficiency virus were developed, it would be the same as for FeLV. 


Feline infectious peritonitis (FIP) is another disease that fits neither three nor four, and rarely number two. The FIP virus vaccine has generally been found ineffective and has produced severe side effects. Among the side effects I have observed with both FIP and FeLV vaccines is induction of the clinical disease they were intended to prevent.


Feline panleukopenia virus is very serious and the vaccine is quite effective, but most cats will not be exposed to the virus and the disease generally affects kittens only. Only those cats that are likely to be exposed would benefit from vaccination, and one vaccination between the age of ten to twelve weeks will protect 95 percent of cats for life. (Schultz) 

With the feline upper respiratory diseases (calicivirus and rhinotracheitis virus as well as feline chlamydia), most are not serious except in very young kittens. These kittens generally contract the disease before vaccines would typically be administered, so the vaccine is not often beneficial. If you choose to immunize for these, use the intranasal form, and do not vaccinate for chlamydia. The chlamydia fraction produces poor immunization. 


Recently a vaccine for ringworm was introduced. I have no direct experience with this vaccine, but I am certain that it will have little benefit and it is probably unsafe. Ringworm is usually the result of immunodeficiency—a chronic disease rather than an acute illness, so the vaccine will not address the cause of disease. I strongly recommend against using this vaccine. 


Finally, while rabies is a very serious disease with the potential to infect humans (this is the reason for excessive vaccination laws), most animals are very unlikely to be exposed. One vaccine at four months of age will protect most cats for life. If one booster vaccination is administered, almost all animals (95 percent) are immunized for life. (Schultz)


In summary, my first recommendation is avoidance of vaccination whenever possible. If the risk is great, one panleukopenia vaccination will adequately protect the cat in almost all cases. The intranasal rhinotracheitis-calicivirus vaccine is relatively effective, but very few cats will benefit from this. Finally, rabies is legally mandated, but one vaccination will generally protect cats that are at risk. 

I never recommend vaccines for feline leukemia virus, feline infectious peritonitis virus, Chlamydia, ringworm, or the feline immunodeficiency virus. And I never recommend booster vaccines; these are always unwarranted.



Clarence Fraser, ed. The Merck Veterinary Manual (Rahway, New Jersey: Merck & Co., Inc., 1986). 

Neil Miller, Vaccines: Are They Really Safe and Effective? (Santa Fe, NM: New Atlantean Press, 1994). 

Phillips, T.R., DVM, and Ron Schultz, Ph.D., “Canine and Feline Vaccines,” in Current Veterinary Therapy XI, Robert Kirk, DVM and John Bonagura, DVM, eds. (Philadelphia: Saunders, 1992). 

Ron Schultz, “Theory and Practice of Immunization” (paper presented at the annual meeting of the American Holistic Veterinary Medical Association, Snowmass, CO, September 1995), 92-104. 


Dr. Don Hamilton practices veterinary homeopathy in New Mexico. The vaccination issue is comprehensively reviewed in a chapter of his book, Homeopathic Care for Cats and Dogs: Small Doses for Small Animals, North Atlantic Books. Please see this book for further information about vaccination or other health problems, or you may call 505 666 2091 to schedule an appointment with Dr. Hamilton. There is a charge for telephone consultations.



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