Vaccination in the Healthy Cattery Concept

Before we can discuss disease prevention, we must first define the fundamental principles of health.

One of the first and most important topics we need to address is vaccination.

Vaccination is one of the most complex and controversial subjects in modern feline breeding. It is a topic that often provokes strong opinions, emotional reactions, and even conflict whenever information challenges long-held beliefs.

Our goal is not to argue or prove that one side is right and another is wrong.

Our goal is to examine the subject as thoroughly as possible and to understand it from multiple perspectives.

In this chapter, we will focus on the FVRCP vaccine.

FVRCP is a combination vaccine designed to protect cats against three viral diseases:

• Feline Herpesvirus

• Feline Calicivirus

• Feline Panleukopenia

These are considered the three most significant viral diseases affecting cats, which is why they were combined into a single vaccine.

According to the standard vaccination protocol, the first vaccine is administered at 8 weeks of age, followed by a booster vaccination 3–4 weeks later.

However, before discussing the advantages and disadvantages of this approach, it is important to understand how a kitten's immune system functions and why this protocol was developed in the first place.

1. Maternal Antibodies Neutralize the Vaccine

When a kitten is born, its immune system is still immature and has not yet learned how to protect the body on its own.

During the first 24–48 hours of life, the mother transfers ready-made antibodies to the kitten through colostrum. These antibodies provide passive protection during the first weeks and months of life—typically until 8–12 weeks of age—while the kitten's own immune system gradually develops.

Maternal antibodies are pre-formed protective proteins capable of recognizing specific viruses. They provide temporary protection, but they do not train the kitten’s immune system. This is a very important distinction.

A vaccine contains a weakened or inactivated virus (antigen) that is intended to be recognized by the immune system and trigger the development of an active immune response.

However, if a vaccine is administered while maternal antibody levels are still high, those antibodies bind to and neutralize the vaccine antigen. As a result, the kitten's immune system does not receive sufficient stimulation to develop its own protection.

In this situation, vaccination may be ineffective because the antigen is eliminated before the body has an opportunity to develop a full immune response.

2. How a Kitten’s Own Immune System Works

True immune training occurs only when a vaccine is administered at a stage when the kitten's immune system has matured enough to respond independently.

At that point, the body recognizes the vaccine antigen, activates immune cells, and develops immunological memory cells. This process is known as the development of active immunity.

Maternal Antibodies

• Ready-made protection• May neutralize the vaccine• Do not create immunological memory

The Kitten’s Own Immune System

• Learns and develops independently• Responds to the vaccine• Creates immunological memory

3. What Is the “Immunity Gap”?

The immunity gap (also known as the "window of susceptibility") is the period during which maternal antibody levels are declining, while the kitten’s own immune system is still not capable of producing a strong and stable immune response.

During this period, the protection received from the mother is gradually weakening, while the kitten’s own immunity is not yet fully developed.

The challenge is that this period is highly individual for each kitten.

For one kitten, it may occur at 7 weeks of age; for another, at 10 weeks; and for a third, closer to 12 weeks.

This is why it is impossible to determine one universal "perfect day" for vaccination that would be equally appropriate for every kitten.

4. The Logic Behind Vaccination Protocols

Modern vaccination protocols were originally developed during the first half of the twentieth century for shelters and populations of stray animals living under high infectious pressure.

If vaccination was delayed for too long, a kitten could become infected before immunity had time to develop.

The goal was simple: reduce mortality and control disease outbreaks.

This is why booster vaccinations at specific intervals were introduced.

Not because a single dose was necessarily "weak," but because it was impossible to know exactly when maternal antibodies would disappear in any individual kitten.

For that reason, vaccinations were repeated every 3–4 weeks in order to "catch the window" when the vaccine would finally be able to work.

Historical Background

• 1940s — development of panleukopenia vaccines begins.• 1950s — the first commercial vaccines become available.• 1960s — vaccine antigens begin to be combined into single products.• 1970s — combination vaccines become the standard, particularly in shelters.

In other words, this approach was developed nearly a century ago for conditions in which large populations of stray animals lived in close contact with one another and faced a high risk of infectious disease exposure.

The primary objective was NOT to create the ideal vaccination schedule for each individual kitten, BUT to control disease outbreaks at the population level.

This system was designed as a population-management solution, not as an optimized approach for home-raised pedigree kittens.

5. When Modern Pedigree Breeding Began in the United States

The popularity of pedigree companion cats began to grow significantly during the 1970s and 1980s.

With the rise of the Internet in the 1990s and early 2000s, private catteries and small home-based breeding programs expanded rapidly.

In other words, mass vaccination protocols had been developed decades earlier to control epidemics in high-risk animal populations.

The challenge for today's pedigree kittens is that the same protocols continue to be applied to animals living under conditions that are fundamentally different from those experienced by shelter kittens of the past.

6. How Vaccination Protocols Developed for Stray-Animal Shelters of the Early Twentieth Century Are Applied Today

According to the traditional vaccination schedule, a kitten receives:

• the first vaccination at 8 weeks of age;• a booster approximately one month later, at 12 weeks.

If the vaccine is administered during the immunity gap (roughly between 7 and 12 weeks of age), kittens whose maternal antibodies have already declined or disappeared, while their own immune systems are still not fully mature, may face significant risks.

The kitten may become ill following vaccination.

Alternatively, the body may experience substantial immune stress with potential long-term consequences, including chronic immune-related disorders.

Some experts believe that if vaccination had not become so widespread, many of these conditions might be far less common today.

The "fortunate" kittens are those whose maternal antibodies remain strong enough to rapidly neutralize the vaccine virus.

7. When Is It Safest to Vaccinate?

Not before 12 weeks of age.

The further vaccination is delayed beyond the immunity gap, the more mature the kitten's immune system becomes.

8. The FVRCP Vaccine Is Not Legally Required

In the United States, the only vaccine required by law is the rabies vaccine.

All other vaccines are considered recommended rather than mandatory.

It is important to note that the rabies vaccine is administered after 12 weeks of age, when the kitten's own immune system is already more stable.

This raises an obvious question:

Why is the first FVRCP vaccine administered during the immunity gap and then repeated at 12 weeks?

The usual explanation is that protection must be provided as early as possible, and the booster is given because it is impossible to know whether maternal antibodies neutralized the first dose.

However, it is important to remember that this logic was originally developed nearly a century ago for stray animals living under conditions of high infectious disease risk.

Today, however, the situation is fundamentally different from the one in which these protocols were originally created.

We no longer live in the era of widespread stray animal populations that characterized the middle of the twentieth century. Most pedigree kittens are born and raised in home catteries, receive high-quality nutrition, remain under constant breeder supervision, and are not exposed to the same infectious pressures that existed decades ago.

Nevertheless, the vaccination protocols have remained largely unchanged.

And this raises another important question.

If vaccination during the immunity gap is considered so critical for protecting a kitten's life, why do owners so frequently observe a decline in their kitten's condition following vaccination?

Throughout my years as a breeder, I have repeatedly encountered situations in which owners contacted me hours or days after vaccination, reporting that a previously healthy, active kitten had suddenly become lethargic, stopped eating, remained inactive, refused to play, and appeared seriously ill.

When owners associate this decline with vaccination, they are often told that the vaccine could not possibly be responsible.

Yet in practice, many veterinarians are well aware that post-vaccination reactions do occur and that some animals experience vaccination far more severely than others.

In some cases, owners must return to the veterinary clinic, undergo additional testing, perform diagnostic workups, and provide medical treatment in order to stabilize the kitten's condition.

Particularly concerning is the fact that these situations often occur when vaccination is administered during the immunity gap—at a time when the kitten's own immune system has not yet fully matured while maternal protection is already fading.

According to a number of holistic veterinary researchers, the body may experience significant immune stress during this period.

Instead of developing strong and stable immunity, some kittens may exhibit signs of immune imbalance that can later manifest as chronic health problems.

Among the most frequently discussed potential consequences are:

• chronic inflammatory conditions;

• recurrent upper respiratory infections;

• chronic rhinitis;

• chronic conjunctivitis;

• gingivitis and stomatitis;

• allergic reactions;

• autoimmune disorders;

• inflammatory bowel disease;

• chronic skin problems;

• increased immune sensitivity to various environmental triggers.

Some experts also point out that following vaccination, certain animals begin to display symptoms resembling the very diseases against which they were vaccinated, particularly respiratory illnesses associated with feline herpesvirus and calicivirus.

Supporters of an alternative approach believe that these cases deserve far more careful investigation than they currently receive.

In their view, the question should not simply be:

"How early can we vaccinate a kitten?"

It should also be:

"Is vaccination necessary at all for a kitten whose living conditions do not involve exposure to sick animals? And if vaccination is necessary, at what age would it be safest for that particular animal?"

Post-Vaccination Problems

Another question that is almost never discussed openly among breeders is not how to treat the consequences of vaccination, but why those consequences are considered normal in the first place.

Virtually every experienced breeder has encountered a situation in which a kitten became ill following vaccination.

Breeders even have their own professional jargon for these cases: “the vaccine broke through,” “the kitten got what it was vaccinated against,” “caught rhino after vaccination,” or “the kitten went into a reaction.”

Most breeders know exactly what to do when this happens. Many keep the necessary medications on hand, have established support protocols, and possess extensive experience in monitoring and treating affected kittens.

They know how to bring kittens back from serious post-vaccination crises.

Yet a much less common question is asked:

If these situations are so common, why are they accepted as an inevitable part of the process?

Many catteries keep kittens until 12, 14, or even 16 weeks of age because they know that some kittens will require intensive care following vaccination.

In practice, most breeders unconsciously accept as normal that there may be a period after vaccination when a kitten requires additional support, monitoring, and treatment.

But when viewed from the outside, an obvious question arises.

Why is a condition that requires observation, medical intervention, and sometimes extensive treatment considered a normal part of a preventive procedure?

Why is the necessity of the intervention itself discussed so rarely?

Why is the usual question:

"How should we vaccinate correctly?"

But only rarely:

"Does this particular kitten actually need this vaccination right now?"

It is at this point that many breeders encounter their own fears.

The fear of going against accepted practices.

The fear of making a mistake.

The fear of taking responsibility for a decision that differs from the standard protocol.

For decades, breeders have been taught that vaccination is an unquestionable good and that any doubts about its necessity are inherently dangerous.

As a result, most people never even consider asking the following question:

If a kitten lives indoors, has no contact with stray animals, does not attend shows, and is not exposed to a high risk of infection, does it truly face the same threats for which the vaccination protocols of the last century were originally developed?

To answer that question, one must first let go of fear and allow oneself to explore the subject openly.

Every informed decision begins not with a ready-made answer, but with a willingness to ask uncomfortable questions.

An Alternative Perspective on Vaccination

Don Hamilton, DVM — Vaccination

If you have read this far, you have probably realized that the issue of vaccination is far more complex than most people have been led to believe.

For decades, breeders and pet owners have been presented with only one side of the discussion. We were told about the benefits of vaccination, but rarely about the potential risks, complications, and long-term consequences.

That is why I believe every breeder and every pet owner should become familiar with the work of Dr. Don Hamilton.

Dr. Hamilton was not simply a veterinarian.

He was a practicing veterinarian, a researcher, and a man who found the courage to publicly ask questions that many others preferred not to ask.

In his book, he describes in detail his professional journey, his observations, and the research that led him to question conventional assumptions about vaccination and its consequences.

One episode in particular made a profound impression on me.

Dr. Hamilton describes presenting his findings to colleagues, expecting a scientific discussion about animal health, vaccine safety, and the implications of the data.

Instead, the conversation quickly shifted to a very different question:

"How are we going to make money if vaccination is eliminated?"

For him, this was one of the greatest disappointments of his career.

He expected a scientific debate—an honest discussion of risks, benefits, research findings, and the search for the safest possible solutions for animals.

Instead, he found that financial and professional interests often carried more weight than concerns about animal health itself.

According to Hamilton, it was at that moment that he truly began to understand how difficult it is to change a system that has been built around long-established protocols and the economic interests connected to them.

Over time, the conflict between his professional convictions and the demands of the system became so significant that he made a difficult decision.

He left conventional veterinary practice and devoted himself to holistic veterinary medicine.

For him, this was not simply a career decision.

It was a matter of professional integrity and personal conscience.

Whether or not you ultimately agree with every conclusion he reached, I believe that anyone making decisions about vaccination should first become familiar with his arguments.

No one can make a truly informed decision after hearing only one side of a debate.

Dr. Hamilton's book does not ask you to accept his conclusions blindly.

Instead, it invites you to examine the evidence, observations, and research for yourself—and then draw your own conclusions.

That is why I recommend it to every breeder and every cat owner.

I understand that many people today simply do not have time to sit down and read an entire book.

For that reason, I recorded an audio version of the chapter titled Vaccination.

The recording is less than two hours long.

If you do not have time to read the book, I encourage you to at least listen to the audio.

Ninety minutes is a very small investment compared to a decision that could influence your animal's health for years to come.

The book, which can be downloaded for free from my website, is here

The audio version, with the same content, is available on my YouTube channel here