Feline Leukemia Virus

Feline leukemia virus (FeLV) in cats is a common disease with a terrible stigma.

What was previously seen as an instant death sentence is now better understood, meaning more cats with FeLV are going on to live full lives.

While cats can still live happy lives with this virus, it is still important to understand the disease and the potential complications it can bring.

So what is FeLV in our feline friends?

In this article we will discuss the details of FeLV in cats, and help you better understand what this diagnosis means for your furry friend.

What Is Feline Leukemia Virus (FeLV)?

Feline Leukemia Virus

Feline leukemia virus is a retrovirus that only infects the cat population.

This virus belongs to the oncornavirus subfamily, which means it is a cancer causing virus that often leads to further complications.

Not only does FeLV cause leukemia in the cat affected, but it also leads to a general suppression of the immune system.

FeLV can only be passed to other members of the cat family, and cannot be passed on to humans or non-feline pets in the home.

FeLV is a virus that only the cat population needs to be aware of, and spreads easiest in multi-cat environments.

FeLV is a common virus in the cat world, with about 2% of cats around the globe currently infected. (Source)

The prevalence varies based on how well vaccinated the region is, and how large of a stray cat population is present.

This virus is most common in cats currently living within stray cat colonies, those rescued from a previous life on the street, cats living with an infected cat, or kittens with infected mothers.

How Do Cats Get Feline Leukemia Virus?

The most common way that cats transmit FeLV is through prolonged, close contact with other cats.

FeLV can be spread to other cats through contact with infected saliva, feces, urine, milk, and bite wounds from FeLV positive cats.

Infected cats can even transmit the virus through regular grooming, as this introduces the other cat to a constant exposure of infected saliva.

Not only can adult cats catch the virus through the direct contact we mentioned above, but pregnant moms can even pass it onto their growing kittens.

FeLV can be transmitted in utero to her growing babies, as well as through the milk they consume each day.

Though this is more unlikely, kittens can also become infected when in contact with their mom’s urine or stool.

As you can see, FeLV is not an aerosolized virus that spreads through contact with infected droplets.

This means that a cat will need to be in direct contact with an infected cat or their wastes, though FeLV is only assumed to live for a couple hours outside of the cat’s body.

This is why the disease is most easily spread with long term exposure to infected cats, as these cats are often in direct contact with the virus many times throughout their lives.

Does Feline Leukemia Virus Spread Easily?

FeLV may be a common virus in the cat population, but it is not highly contagious.

Unlike other viruses such as Feline Herpes or Panleukopenia, FeLV often requires prolonged direct contact for infection to occur.

Most cats will either need to frequently groom or fight with an infected cat to acquire the virus, with a small percentage being infected through sharing litter boxes.

While it is easily spread when cats are in regular close contact with an infected cat, it is not highly contagious in itself.

The other situation in which it may be considered “easy” to spread is if an infected mother gives birth to kittens.

Kittens can be exposed to the virus in utero, through their mother’s milk, and through regular grooming.

However, most cats with FeLV are either infertile due to the virus, or will experience prenatal death and resorption of their growing kittens.

What Complications Can Feline Leukemia Cause?

As we mentioned before, FeLV carries a devastating stigma. While many believe that FeLV will automatically decrease a cat’s quality of life, this is not always the case.

Up to 30% of cats will effectively eliminate the virus with their immune response (known as an abortive infection), and will go on to live a normal life.

Cats will still be able to infect other cats when the virus is present within their body, but they may be able to eliminate the virus before they ever develop serious health complications as a result.

However, this is the best case scenario, and is considered the most rare of all possibilities.

If 30% of cats will effectively eliminate the virus, then 70% of cats will fall victim to a permanent infection of FeLV.

These cases are known as either progressive or regressive infections, varying in severity based on the body’s immune response to the virus.

These are the cats that will easiest spread the virus to other cats in their life, as well as experience FeLV related complications down the line.

It can take years for cats to develop secondary complications from the virus, which is why so many cat owners are unaware that their pet is infected.

This is also when most infection occurs within multi cat homes, as the owners were simply unaware of what preventative measures should have been taken.

The leukemia is serious in itself, but it is often the secondary disease down the line that makes this virus so devastating.

Cats with progressive infections of FeLV may experience suppressed immune systems, chronic infections, infertility, blood disorders, and even cancer.

FeLV is the most common cause of lymphoma in cats, with 50-70% (source) of all lymphoma cats testing positive for FeLV.

Cats with progressive FeLV are most contagious to other cats, but all infected cats can spread the virus at any point throughout their infection.

Symptoms of Feline Leukemia Virus

When a cat is first infected with FeLV, they won’t often display any sign of illness until further down the line.

The typical decline in health occurs within months to years after being infected, with rare cases displaying symptoms within weeks of infection.

No matter how long it takes for a cat to display symptoms related to FeLV, each infection typically leads to a general decline in health.

Most owners simply state that their cats began to feel unwell, with multiple vague symptoms that point to a general decline.

Some of the most common symptoms of FeLV in cats include:

  • Weight loss over time
  • Decreased appetite
  • Dull or lackluster coat
  • Chronic skin infections, UTI’s, or URI’s
  • Enlarged lymph nodes throughout the body
  • General lethargy
  • Chronic GI upset such as diarrhea or vomiting
  • Inflammation within the mouth
  • Fever
  • Behavioral changes
  • Abortion of kittens or other reproductive complications

Cats with FeLV may experience some of these symptoms once after their initial infection, or they may develop chronic flare ups throughout their life.

Some cats will also develop FeLV related disease in the later stages of the condition, which will lead to a variety of additional symptoms based on the complication they are facing.

Diagnosing Feline Leukemia Virus

Thankfully, FeLV in cats is easy to diagnose, and most clinics have access to the tools needed to test your cat.

The first tool used to detect the virus in cats is an ELISA test that screens for the protein component of the virus, which can be performed in your vet’s office.

If this test comes back positive for FeLV, many vets will suggest sending out a blood sample to a lab that can detect how far along your cat’s condition is.

This laboratory test is referred to as an IFA test, which searches for the virus within the white blood cells.

This not only confirms the infection, but can determine how progressed your cat’s condition is.

Most cats that test positive on the IFA test are those with a progressive infection, and will often display disease related complications at some point throughout their life.

It can take up to 30 days after exposure to the virus for a cat to test positive for FeLV, so it’s best to test cats twice over a 60 day period if they were recently exposed to an infected cat.

It’s also worth noting that some cats will fight off the FeLV virus naturally, so you should always retest your cat in the years following their first positive test.

Can You Treat Feline Leukemia Virus?

Unfortunately, there is no set treatment for FeLV in cats.

Most cats with regressive or progressive FeLV will eventually pass due to complications of the virus, ranging from chronic illness to forms of cancer.

The best management options involve treating any complications as they come, and making the cat as comfortable as possible during any flare ups.

Most cats either pass away or have to be euthanized within 2-3 years of initial diagnosis.

This of course varies based on how severe their infection is, and whether or not they are experiencing severe health complications.

Is There A Vaccine For Feline Leukemia?

There is a vaccine available to prevent the spread of FeLV in cats.

This vaccine requires an initial 2 doses to stimulate the proper immune response, and will require boosters every 3 years to maintain immunity (or as recommended by your veterinarian).

This vaccine is highly recommended for any cat that may come in contact with FeLV infected cats, or those that spend any time outdoors.

If you think your cat can benefit from the FeLV vaccine, we suggest speaking with your veterinarian about whether or not it’s right for them.

Can Cats With FeLV Live A Normal Life?

The information we discussed above may be daunting, but it’s important to remember one thing; FeLV does not have to be a death sentence.

It’s unfortunate how many cats in shelter and rescue situations are euthanized due to their positive result, but the diagnosis itself does not mean your cat will have a life filled with suffering.

Yes, they may struggle at some point, but many can live a normal life until then.

If a cat is generally healthy at the time of diagnosis, most will have a standard life expectancy of 2-3 years.

Your cat could also be one of the lucky ones that fight off the virus with their immune system, meaning they could have many years ahead of them before any complications arise.

If your cat is not suffering at the point of their diagnosis, euthanasia does not have to be the only option on the table.

Cats with FeLV can continue to live normal lives as long as you are dedicated to monitoring their weight, their appetite, their energy levels, their litter box habits, and their general appearance in terms of skin and coat health.

Staying on top of any changes can allow you to seek veterinary care at the start of any health complications, giving them the chance at proper management.

Your cat’s life may be shorter than others, but their life can still be wonderful up until you have to say goodbye.

Again, every case will vary, so we always suggest speaking with your vet about your cat’s prognosis.

Can Cats With FeLV Be Around Other Cats?

This is where things get a bit complicated when discussing FeLV in cats.

The issue of FeLV cats living in homes with other cats is why they get euthanized so often in shelter situations, as it can be risky to house them with cats free of the virus.

To help you make an educated decision on what is best for your home environment, let’s discuss the facts.

First, it’s important to understand that FeLV cannot be passed on to humans or any other pets that are not cats.

This means that a FeLV positive cat can live safely in a home free of other pets, and can even live with other animals outside of their species.

This means these cats can live happily with dogs, rabbits, birds, and any other animals outside of the feline realm.

If your FeLV positive cat is the only cat in your home, then this is not an issue you need to be concerned with.

However, no matter what form of FeLV your cat develops or how progressed their condition is, they can always infect other cats.

While some cats are certainly considered lower risk than others, it can never be ruled out completely.

Anytime you are housing a FeLV positive cat with a FeLV negative cat, there is always a risk.

Choosing to bring a FeLV positive cat into your home with FeLV negative cats will need to be a personal decision that you make based on the information available to you.

With that in mind, there are ways to decrease the likelihood of your FeLV negative cat becoming infected with the virus.

You can offer the other cats in your home the best chance at success by making sure they are fully vaccinated against FeLV, giving them booster vaccines every 3 years, keeping their food and water bowls separate, as well as limiting any fights within the home.

This will never offer your cat 100% protection, but it certainly decreases the risk.

Final Thoughts

As you can see, FeLV is a complicated condition with varying stages of severity.

Be sure to review the information that we discussed above, and you can better understand what this diagnosis means for your feline friend.

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