Often when someone says their cat has an upper respiratory infection, they are advised by friends who have had cats for years that they should sprinkle some lysine on the sick kitty’s food. However, a look over the body of research available indicates that lysine supplementation does not help cats with Feline Herpesvirus (FHV-1).

What is Feline Herpesvirus?

Feline Herpesvirus (FHV-1) is one of the main causes of upper respiratory infections in cats, and it is directly or indirectly accounts for over 90% of feline eye diseases. The virus is very common, and many cats are exposed to it as kittens by an infected mother caring for them.

The virus transmits between cats through:

• Direct contact through saliva or through nasal or eye secretions
• Inhaling sneeze droplets of an infected cat
• Sharing food bowls and litter boxes
• Sharing contaminated bedding or grooming aids

FHV-1 Infection Symptoms

At the time the cat is infected, the main symptom of FHV-1 is an upper respiratory infection, including discharge from the eyes and nose, sneezing, fever, lethargy, and sometimes coughing.

After the upper respiratory symptoms are gone, the virus remains in an inactive status in the nerve cells of most cats. A little under half of those cats will have the virus reactivate at some time later during their life. The FHV-1 virus reactivates when the cat is under stress, including emotional or physical stress. Additionally, some drugs like corticosteroids are likely to reactivate latent FHV-1 in a cat.

When the virus reactivates in a cat, the cat might show upper respiratory symptoms mentioned above, or the kitty might instead only shed the virus, becoming contagious to other cats without appearing sick.

Less commonly, cats with chronic FHV infections have inflamed corneas (the clear covering of the eye) that can lead to ulcers in the eye.

Why Do People Expect Lysine Would Help with FHV-1?

Dr. Andrew Weil, an integrative physician for humans, recommends that people with the viruses that cause herpes in humans, HSV-1 and HSV-2, reduce the amount of the amino acid arginine in the diet and increase their intake of the amino acid lysine to reduce symptoms. There is mixed evidence about this, practice, but it is frequently repeated advice both around the internet and through veterinarians.

The theory behind this is that lysine interferes with the replication of the virus by blocking the body’s uptake of arginine, which can worsen herpes outbreaks. Human bodies create arginine naturally but require dietary lysine, so dietary modifications and/or supplementation are suggested.

Cats, Lysine and Arginine

Cats and humans aren’t the same. An overview of all of the previous research done on lysine and FHV-1 showed that lysine does not inhibit arginine in cats. This means that there isn’t really a purpose behind supplementing cats with lysine.

Unlike with humans, cats don’t create arginine. Finding ways to reduce arginine in their diet isn’t necessarily beneficial because arginine deficiency can result in excess ammonia in the blood, a condition that can be fatal.

The evidence found that orally supplementing cats with lysine was not effective and in some cases can enhance FHV-1 viral replication, making infection worse.

Belief Perseverance

When this research first came out last year, internet discussions about it tended to say, “I have seen kittens get better when supplementing them with lysine, so I will continue to give it to sick kittens.” Comments on articles dismissed the research instead of looking more closely at it to see if maybe their perceptions of it had been flawed.

Maintaining beliefs and theories against explicit conflicting evidence isn’t unusual. The psychological phenomenon actually has a name: belief perseverance. Behaviors we think are beneficial are especially hard to break, but over time, this may change in the face of the evidence that cat physiology doesn’t work like human physiology.

Do you think that one day, giving cats with upper respiratory infections lysine will be like feeding cats milk is today: a practice that used to be common and is now considered old-fashioned?

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Research and further reading

Bio Med Central, Lysine supplementation is not effective for the prevention or treatment of feline herpesvirus 1 infection in cats: a systematic review
International Cat Care, Feline herpesvirus (FHV) infection
Michigan Veterinary Medical Association conference proceedings, FHV-1, Can One Virus Cause All Those Diseases?
Journal of Nutrition, Excess Dietary Lysine Does Not Cause Lysine-Arginine Antagonism in Adult Cats

Image credits

Creative commons images courtesy flickr/pmarkham, kayveein
depositphotos/designer491, funny_cats, belchonock

Some of the same characteristics that make cats great at living alongside human in such a variety of situation so how adaptive they are. But that same adaptive nature means that they will live for extended periods of time at a chronic low level of dehydration.

Cats, just like you, get dehydrated when they don’t take in enough water. Since cats are descended from desert-dwellers, they are good at extracting moisture from their prey, and they don’t feel thirsty to go drink water until they are 3% dehydrated. Cats don’t show any obvious clinical signs of anything being wrong until they are more than 5% dehydrated.

How to Help Your Cat Stay Hydrated

There are a few simple things you can do that will help your cat stay more hydrated and more healthy.

Kick the Kibble Habit

A lot of cats are on a kibble-only diet. Many vets will even recommend kibble because they feel that it’s a convenience food that that families will comply with. What many people who carefully select kibble don’t realize is that it is very low in moisture. Kibble is 6-10% moisture, while canned food is 75-80% moisture. For a cat whose system is used to extracting moisture from her food, kibble can leave a cat in a chronic low-level dehydration.

Getting cats off of kibble and onto a diet with more moisture can be difficult, and many people give up. Like everything with cats, it can take a lot of patience on your part to overcome your cat’s attachment to the stuff they spray on the outside of the kibble to make it taste so good. It took a full six months to fully transition my three cats from kibble to canned food, and I admit there were times I wanted to give up.

Once your cats are on canned food, it may seem like they never visit the water bowl any more since they get so much of their moisture directly through their food. You can even mix a little bit of water into your cat’s dry food, as long as your kitty will tolerate the slightly soupy texture.

Water Everywhere

One of the tricks that Dr. Sherri Basso taught me over ten years ago was to put water bowls in many rooms of the house. As she put it, “Every time your cat walks into a room, he should see a bowl and think, ‘Huh, I should have a little to drink!'”

It took some getting used to, and I tripped over a water bowl in the bedroom more than once, but it made a big difference for my cat Cyrano at the time who had chronic kidney disease. That lesson has stayed with me, and I have water available in multiple rooms of my house. The cats drink from all of them!

If you can’t have water in every room of the house, at least make sure there’s water available somewhere well away from your cat’s food dish. A lot of cats prefer not to drink near their food dish, possibly because they are hard-wired to think that a water source near their killed prey is polluted. You may be surprised how much more your cat drinks from the water bowl that Is far from their food bowl than the one near it.

Running Water

A lot of cats really like to drink from flowing water. That’s why there are so many goofy videos all around the Internet of cats drinking from faucets.

If your cat loves to drink from the tap and you are home all day to turn it off and on for your kitty, that might be a great solution. For some of us, a fountain is a great alternative to being on call at the water tap.

There are several different kinds of water fountains on the market. All of them use some kind of pump to recirculate water, and some feature falling water while others have water that flows over a surface. Some humans love the sound of falling water while others find it uncomfortable to listen to without extra trips to the restroom, so consider your cat’s preferences and those of the humans in your household.

The best fountain for your cat is one you can keep clean, so pay attention to the design and features, and make sure it’s a commitment you are willing to keep up before making it your cat’s sole source of available water.

The More Options, the Better

Helping your cat to stay hydrated is important to keeping your kitty’s health at its peak. Consider using a combination of high-moisture food, plentiful water bowls, and even flowing fountains to help keep your cat hydrated and happy.

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Research and Further Reading

Candyce Jack LVT and Patricia Watson LVT, Veterinary Technician’s Daily Reference Guide
Little Big Cat, Dr. Jean Hofve, DVM, Why Cats Need Canned Food

Photo credits

depositphotos/kozorog
depositphotos/Madhourses
depositphotos/bollwerk