Search

*Disclaimer: Tossions earns a commission from qualifying purchases.

The 8 Best lysine for cats of 2025

Are you trying to find lysine for cats among various brands on the market but aren’t sure where to begin? To assist you in finding the right one, we’ve put together a list of the 7 best to help you pick the perfect one!

We investigated and evaluated a number of the top-selling lysine for cats on the market in order to create our list of the best. Making a decision among the many options available is never simple. There are an infinite number of models available, each with a distinct price. And as you’ll find out, the best options aren’t usually the ones you imagine! This comparison is rich and relevant because of the numerous factors that were employed. You will find products featured in this ranking not only based on their pricing but also on their features and other customers reviews. To write this review, we completed 28 hours of research and did 58 lysine for cats tests. You won’t need to pick products at random any more. If you’re unsure of what to look for, browse our list and consult the buying guide!

An overview of our top picks

Table of contents

The best lysine for cats you can buy today

No. 1
Vetoquinol Viralys L-Lysine Supplement for Cats - Cats & Kittens of All Ages - Immune Health - Sneezing, Runny Nose, Squinting, Watery Eyes - Flavored Lysine Powder
  • Daily L-Lysine supplement for cats helps support a strong immune system and eye & respiratory health
  • Helps manage common feline health issues such as sneezing, runny nose and watery, inflamed eyes
  • Lysine powder for cats & kittens provides specially-formulated immune support for as long as needed
  • Cats love the highly-palatable fish and poultry flavor; simple to dose and easy to administer
  • Delivers veterinarian-recommended amount of Lysine: cats = 500mg 2x daily, kittens = 250mg 2x daily
SaleNo. 2
Vetoquinol Viralys Gel L-Lysine Supplement for Cats, 5oz - Cats & Kittens of All Ages - Immune Health - Sneezing, Runny Nose, Squinting, Watery Eyes - Palatable Maple Flavor Lysine Gel
  • Daily L-Lysine supplement for cats helps support a strong immune system and eye & respiratory health
  • Helps manage common feline health issues such as sneezing, runny nose and watery, inflamed eyes
  • Lysine gel for cats & kittens provides specially-formulated immune support for as long as needed
  • Cats love the highly-palatable maple-flavored gel; simple to dose and easy to administer
  • Delivers veterinarian-recommended amount of Lysine: cats = 500mg 2x daily, kittens = 250mg 2x daily
No. 3
L-Lysine Supplement for Cats 900mg/scoop - Cat Supplement for Sneezing and Runny Nose, Cold, Immune Support, Eye Function, and Respiratory Health – Lysine Powder
  • Cat Immune Support - Coco and Luna L-Lysine for cats helps support a strong immune system and eye function providing cat vitamins for older cats and kittens alike.
  • Respiratory Health - Our formula promotes normal respiratory function and health which can help fight against issues such as sneezing, watery and inflamed eyes, and runny noses.
  • Easy to Serve Powder - Our formula has the best natural ingredients, adjusted for cats in an easy to serve format that can be given with food or as a daily treat.
  • A Brand You Can Trust - We understand how much your pet’s health and wellbeing mean to you, so our products are manufactured in FDA-registered facilities that are NSF and GMP-certified in the USA.
  • Made in the USA from US and Globally Sourced Ingredients - All our products are made in the USA and are veterinarian approved as well as hypoallergenic. Our L-Lysine powder helps bring your cat nose relief and may help with sneezing and other cold-like symptoms.
No. 4
VetriScience Vetri Lysine Plus for Cats, 90 Chicken Flavored Chews - Immune and Respiratory Support Supplement for Cats
  • Lysine is recommended for cats that need added immune support, respiratory health support and for other conditions that are responsive to lysine
  • Lysine is an essential amino acid for felines that must be ingested through food or supplements
  • Lysine is often Recommended to support immune health-especially when cats are being boarded or live in a multi-cat household
  • Vetri lysine plus comes in a delicious chicken Liver bite sized chew that cats love
  • Vetriscience products are manufactured in the U. S. A. And are backed by a 100% satisfaction
No. 5
Tomlyn Immune Support Daily L-Lysine Supplement, Fish-Flavored Lysine Powder for Cats and Kittens, 3.5oz
  • L-Lysine supplement for cats; supports normal eye function, respiratory health, strong immune system
  • Helps manage common feline health issues; sneezing, runny nose, squinting and watery, inflamed eyes
  • One to two scoops daily provides support for the immune and respiratory system for kittens and cats
  • Our vet-quality L-Lysine powder provides immune support for respiratory issues for as long as needed
  • Cats love our tasty, palatable fish-flavored powder; easy to dose and administer, simply add to food
No. 6
Felisyl L-Lysine Gel for Cats - Immune System Support - Supplement Support for Healthy Tissue, Respiratory, and Vision - Salmon-Flavored - Made in The USA - 5 oz
622 Consomer Reviews
Felisyl L-Lysine Gel for Cats - Immune System Support - Supplement Support for Healthy Tissue, Respiratory, and Vision - Salmon-Flavored - Made in The USA - 5 oz
  • Immune Health Boost: Empower your cat's immune system to fend off threats and maintain peak health. By strengthening their natural defenses, you're investing in their long and joyful life.
  • Enhanced Respiratory Function: Breathe easy knowing your cat's respiratory system is supported for optimal well-being. Whether they're exploring indoors or embracing outdoor adventures, healthy breathing is vital.
  • Essential Amino Acid: L-Lysine, a crucial building block, ensures your cat's vitality from the inside out. It's the cornerstone of their well-being, promoting overall health and resilience.
  • Easy-to-Administer Gel: Hassle-free application that your cat won't resist, making wellness routines a breeze. No more struggle or stress during supplementation – just a happy and contented feline friend.
  • Premium Quality: Crafted with care, our gel is a testament to the highest standards of quality and efficacy. Your cat deserves nothing but the best, and Felisyl L-Lysine Gel delivers just that.
  • Vet-Recommended Formula: Trusted by veterinarians for its proven benefits and positive impact on cats' lives. When you choose Felisyl, you're choosing a formula endorsed by those who prioritize feline health.
  • Happy and Healthy Cats: Witness the transformation as your beloved feline friend experiences newfound energy and joy. A healthy cat is a happy cat, and Felisyl L-Lysine Gel ensures plenty of both.
SaleNo. 7
NOW Foods Pet Health, L-Lysine Supplement, Powder, Formulated for Cats, NASC Certified, 8-Ounce
  • IMMUNE SYSTEM SUPPORT FOR CATS: NOW Pets L-Lysine Powder helps support a healthy immune system, normal respiratory health, and also helps to maintain ocular health.
  • VETERINARIAN RECOMMENDED: NOW Pets L-Lysine Powder is recommended by renowned veterinarian Dr. Barbara Royal, DVM, CVA, founder of the Royal Treatment Veterinary Center.
  • NASC CERTIFIED: NOW Pets has been certified by the National Animal Supplement Council (NASC), an organization that protects and enhances the integrity of the animal health product industry
  • NOW Pets premium pet supplements are formulated and manufactured with the same attention to quality and detail NOW puts into their supplements intended for humans, from the sourcing of top-quality ingredients to finished product testing.
  • Packaged in the USA by a family owned and operated company since 1968.
No. 8
L-ysine Supplement for Cats - Immune Support - 60ML Lysine for Feline Respiratory, Sneezing, Runny Nose, Eye Function - Natural Cat Antibiotic Drops - Roast Chicken Flavor
  • Immune Support for Cats: Our L-Lysine for cats is specially formulated to support your cat's overall well-being. It promotes normal eye function and respiratory health while strengthening the immune system to help manage common feline issues such as sneezing, runny nose, squinting, and watery, inflamed eyes.
  • Premium Ingredients: Our Lysine drops for cats are enriched with a variety of natural ingredients and essential vitamins to promote feline health. Key components include L-Lysine HCl for immune support, Astragalus and Codonopsis for vitality, Atractylodes Macrocephala for digestive health, Burdock Seed for skin and coat nourishment, and a blend of Vitamins for overall well-being.
  • Super Delicious: Our lysine cat treats is made into a delicious chicken flavor that even picky fur babies will absolutely love. It is suitable for cats of any age, breed, and size, helping to keep your furry friend healthy and happy with our irresistible formula.
  • Best Trust for Cats: Our lysine supplement for cats is made in the USA with a veterinarian-approved formula, using safe ingredients that are free from grains, alcohol, and gluten, and without any additives or harmful chemicals. This makes it completely safe for all cats.
  • No More Worries: When using our lysine liquid for cat, you don't have to worry about messy powders, annoying capsules, tablets, or hard-to-chew solids. They can be used directly or mixed with food, water, or milk, and even fed directly to your cat.
No. 9
Pet Naturals Lysine for Cats, Chicken Flavor, 60 Chews - Immune and Respiratory Support for Cats - No Wheat or Corn - Vet Recommended
  • Lysine Immune Booster for Cats – Quality lysine supplements for cats are recommended to support immune system and upper respiratory health, as well as boost the production of antibodies for added protection. Keep your feline friends healthy with lysine chews
  • Powerful, Effective Formula – Each L-Lysine soft chew contains 250mg of lysine per treat, the optimal amount to keep your kitty feeling healthy and happy. Give 1-2 chews per day to manage or prevent sneezing, runny rose, and watery, irritated eyes
  • 60-Day Supply – Get your money’s worth. Our affordable lysine supplement offers a 60-day supply for most cats and is ideal for multi-cat households
  • Tasty Chicken-Liver Flavor – Pet Naturals L-Lysine bite-sized chews come in a fun fish shape with delicious chicken-liver flavor. These lysine treats for cats are the tastiest way to support your pet's immune system every day
  • Breathe Easy – You can feel confident giving Pet Naturals L-Lysine. Our high-quality lysine supplement for cats is formulated with vet approval, and contains healthful ingredients with no wheat, corn, or artificial ingredients
No. 10
Pet Honesty Cat Multivitamin Crunchy & Creamy Chews - Cat Treats for Health + Immune, Cat Joint Support, Skin & Coat, & Digestion - Omega 3s, Lysine & Probiotic Cat Vitamins - 30 Day Supply
  • A Texture and Taste Cats Love: Pet Honesty’s Multivitamin for cats is a delicious supplement that contains essential vitamins, minerals, and nutrients to support your cat’s overall health. Powerful, wholesome ingredients are packed inside a unique texture format: crunchy on the outside and creamy on the inside, offering a taste and texture combination that cats love.
  • Help Support Overall Health & Immune Function: These easy-to-give chews contain key functional ingredients to support overall immune, heart, joint, skin, and gut health. Plus, with a taste and texture 4/5 cats love*, giving them a chew is a simple way to ensure your cat is getting a well-rounded variety of important nutrients added to their diet. *Based on a 2022 feeding study
  • Made with Natural & Other Premium Ingredients Like Lysine, Beta Glucan, and Omega-3s: Multivitamin chews are filled with health-supporting ingredients you can trust. Lysine, an essential amino acid, supports immune and respiratory health. Beta Glucan, a premium prebiotic, supports gut and digestive health. Omega-3s, fatty acids from fish oil, flaxseed, and green-lipped mussels, promote skin, coat, and joint health. All in a delicious chicken-flavored chew your cat will love!
  • Pet Honesty Pledge: A taste your pet will love and results you can trust. Made with the most effective natural and premium ingredients. Formulated without corn, wheat, or soy. No artificial preservatives, colors, or flavors.
  • Manufactured in the U.S.A. | NASC Member Company: All Pet Honesty products are made in the US with US and globally sourced ingredients and are produced in a GMP-compliant facility that meets the highest safety standards, so you can rest assured you're giving your pet the best quality product possible! Pet Honesty is also a NASC member company, meaning it has met the highest quality and compliance standards for pet supplements.
No. 11
L-Lysine for Cats and Kittens - 900 mg L Lysine Powder for Cats for Immunity & Respiratory Support - Cat Supplement with L-Lysine, Prebiotics, Krill, & DMG for Immune System, Eye Health & Sneezing
  • L-LYSINE POWDER FOR CATS - Boost immune system and provide cat respiratory support to help keep your cat feeling their best!
  • LOADED WITH PREBIOTICS, KRILL, & DMG - This Booster provides additional immune support for cats by promoting gut health, omega 3 fatty acids, immune system defense!
  • CONVENIENT POWDER SUPPLEMENT FOR CATS: The perfect food topper for a healthy cat diet, the powder form is more bioavailable for cats, making it easier to digest!
  • FELINE L LYSINE - Each scoop of our Lysine for Cats Powder contains 900 mg of L-lysine for cats, 400 mg of prebiotics, 250 mg of Krill, and 50 mg of DMG
  • 60 DAY FELINE SATISFACTION GUARANTEED: 3rd Party Laboratory Tested, Trusted Vitamins & 3rd Party Certified Pesticide Free
No. 12
Vetoquinol Enisyl-F Lysine Bites: L-Lysine Chews for Cats & Kittens - Chicken Liver-Flavor, 6.4oz (180g) Reclosable Bag
  • Daily L-Lysine supplement for cats helps support a strong immune system and eye & respiratory health
  • Helps manage common feline health issues: sneezing, runny nose, squinting and watery, inflamed eyes
  • Delivers veterinarian-recommended amount of Lysine: cats = 500mg 2x daily, kittens = 250mg 2x daily
  • Lysine bites for cats and kittens provides specially-formulated immune support for as long as needed
  • Cats love the highly-palatable chicken liver flavor chews; easy to dose and administer; portable
No. 13
Horbäach L-Lysine Powder for Cats 500mg | 12oz | Cat Health Supplement | Non-GMO, Vegetarian Formula | by River & RULA
  • L-LYSINE FOR CATS: Treat your Cat to River and Rula's L-Lysine Powder, the ultimate pet supplement!
  • COMPLETE FORMULA: Features 500 mg of L-Lysine Hydrochloride per serving for maximum daily support
  • CONVENIENT POWDER: Complements a diet rich with nutritious foods and provides essential amino acids
  • RIVER & RULA: Two pups on a mission to promote high-quality nutrition for our dog and cat friends
  • TAIL WAGS GUARANTEED: Laboratory Tested, Trusted Vitamins, made by Horbaach Manufacturers
No. 14
Alpha Paw - Human Grade for Pets - Cat Lysine Supplement - Extra Servings 5-10 Month Supply - Natural Lysine (8 Ounces/227 Grams)
  • IMMUNE SUPPORT: Human grade for pets. Daily Lysine supplement provides essential amino acids to help support a strong immune system.
  • EXTRA SERVINGS: 8 oz container = 300 One-Scoop Servings or 150 Two-Scoop Servings. Enough for 5-10 months. Won’t expire.
  • ALL NATURAL: Fend off sneezing, runny eyes, and upper respiratory infections with natural immune system support.
  • FLAVORLESS: Even picky eaters won’t notice. Flavorless and odorless Lysine Powder, sprinkle over existing food.
  • HUMAN GRADE, USA Sourced: Human grade L Lysine. USA produced in a GMP-compliant facility. Alpha Paw is based in Austin, Texas
No. 15
Vetoquinol Enisyl-F Oral Paste: L-Lysine Supplement for Cats - Tuna Flavor, 3.4oz (100mL) Pump
  • Daily Lysine supplement for cats helps support a strong immune system and eye & respiratory health
  • Helps manage common feline health issues: sneezing, runny nose, squinting and watery, inflamed eyes
  • Delivers veterinarian-recommended amount of Lysine: cats = 500mg 2x daily, kittens = 250mg 2x daily
  • Lysine paste for cats and kittens provide specially-formulated immune support for as long as needed
  • Cats love the highly-palatable tuna-flavored paste; easy to dose and administer; add to paws, nose
No. 16
Balanced Breed L-Lysine Cats Immune Support Soft Chews Made in USA Non-GMO Vet-Pharmacist Approved Krill Oil Omega 3 Cat Vitamins Indoor Cats Supplements Asthma Relief Cat Lysine Allergy Relief 60 ct.
  • Ultimate allergy relief: Our cat allergy relief for cats combines cat supplements & vitamins, omega 3 for cats, cat nasal relief, cat skin allergy relief, cold remedy for cats, lysine cat treats, and sneeze relief for cats.
  • Respiratory health boost: Designed for cat asthma relief, these chews are packed with vitamins for cats, cat sneezing relief, cat vitamins and supplements, cat cold relief, cat immune booster, cat decongestant, and cat respiratory support.
  • Immune system support: Our chews offer cat nose relief, lysine treats for cats, supplements for cats, immune support for cats, cat congestion relief, cat health supplements, cat lysine treats, and lysine cat supplement.
  • Comprehensive cold remedy: cat cold remedy with tasty lysine chews for cats & a potent l-lysine supplement for cats. It supports cat immunity, addressing cat runny nose, feline l lysine, feline nose relief for cats, cat cough relief, & cat allergies.
  • Satisfaction guaranteed: Unlike most pet supplement brands, we offer a true 30-day money-back guarantee. If you or your furry companion are unimpressed, contact us directly for help honoring this guarantee. Ensure pet happiness - try us risk-free!
No. 17
Trulysine Plus L-Lysine for Cats Immune Support Oral Powder 8oz/226g - Cats & Kittens of All Age, Sneezing, Runny Nose Squinting, Watery Eyes-Fish & Poultry Flavor (U.S.A)(225 Grams (900mg / Scoop))
  • Lysine Plus highly palatable oral granule powder formulated is recommended by veterinarians for feline conditions that are responsive to Lysine. L-Lysine Powder helps support a healthy system, normal respiratory health, and also helps to maintain ocular health. Delivers veterinarian-recommended amount of Lysine: cats = 1 Scoop; 1 or 2x daily, kittens = 1/2 Scoop; 1 or 2x daily
  • Dimethylglycine (DMG) DMG is an intermediary metabolite that improves cellular metabolism especially under stressful conditions. DMG provides the building blocks for synthesis of vitamins. It also supports all aspects of response.
  • Lysine Plus may help manage signs associated with the Feline, issues such as sneezing, watery and inflamed eyes, and runny noses
  • DELICIOUS POULTRY AND FISH FLAVOR ORAL GRANULES POWDER : Oral granule powder flavor will make easy to give to your cat or kitten, just sprinkle over or mix in their food. Easy to administer
  • Trulysine Plus products are veterinarian formulated and manufactured in the USA and contains no wheat, corn or artificial ingredients
No. 18
Optixcare 72-2 L-Lysine Chews for Cats & Kittens, 60 Count (Pack of 1)
  • Tasty chicken flavor cats love
  • Resealable pouch
  • One bag lasts 2 months
No. 19
Lysine for Cats - L-Lysine Supplement for Cats & Kittens, Immune Support, Cold & Allergy Relief, Sneezing, Runny Nose, Feline Respiratory, 60ml Drops with Colostrum, Taurine, Vitamins & Minerals
  • L-Lysine Supplement for Cats: Featuring an advanced formula, our cat lysine drops are specifically designed to provide comprehensive health for your cat, supporting immune, allergies, sneezing, respiratory, and eye health
  • Natural Premium Ingredients: This liquid lysine for cats features a variety of carefully selected active ingredients, including L-Lysine, L-Taurine, colostrum, astragalus, codonopsis, burdock, vitamins, Minerals, and is gentle with no irritation
  • Suitable for Kittens and Cats: Better suited to the health needs of kittens and cats of all ages, our L-Lysine drops for cats feature a roasted chicken flavor and are enriched with additional nutrients such as colostrum, vitamins, and minerals
  • Nutrient Intake Assistant: Compared to powders, tablets, and capsules, the liquid form of cat L-Lysine drops can assist with more thorough absorption, with a very simple daily supplementation routine, you can either feed the drops directly or mix them with food, milk, or water
  • Tender Loving Care for Feline: Made in USA with all-natural ingredients, our drops are free from any chemicals, artificial flavors, or preservatives, offering a safe daily cat supplement with L-Lysine
No. 20
L-Lysine for Cats - Lysine Powder Supplement - 900mg/serving - Immune Support for Cats & Kittens - Sneezing, Runny Nose, Squinting, Watery Eyes, Cold, Eye Function, Respiratory Health - with Taurine
  • L-Lysine for Cats: Elevate your pet's health with our easy-to-administer cat lysine powder, fortified with vital L-Lysine to bolster immunity and combat the discomfort of feline respiratory challenges
  • Cat Immune Support: Provide essential nourishment with our cat supplements & vitamins, fortified with key nutrients to strengthen your feline companion's immune system and overall well-being
  • Respiratory Health: Our L-lysine powder for cats supports normal respiratory function and health, aiding in the alleviation of issues such as sneezing, watery and inflamed eyes, and runny noses
  • Eye Wellness: Enhance your cat's vision and eye health with our lysine supplement, specially formulated to support optimal eye function, ensuring clear and bright eyes for your beloved pet
  • Convenient Powder Format: Our easy-to-use powder offers a more convenient alternative to lysine treats for cats, allowing for effortless administration and precise dosing tailored to your pet's needs

How to choose a good lysine for cats

Does the idea of finding a fantastic lysine for cats make you anxious? When it comes to purchasing this product, specifically when deciding which model to select, has your head been spinning between options? You are not alone if that is the case. We are aware of the pressure involved in the purchasing process!

Your presence here indicates that you are interested in lysine for cats. Before choosing which product would be the best for your needs after being inundated with information, locate a reliable source with genuine selections. You can get that information from a variety of sources, including buying guides and rating websites, word-of-mouth recommendations from friends and family, online discussion forums where users can share their own experiences, product reviews that can be found all over the internet, and YouTube channels. You can only get the right product through exhaustive analysis. But you realize that’s not always simple. In order to ease your concerns, we have taken the time to develop a list of the top lysine for cats products available right now. You might be wondering how we came up with the list. How was this buying guide developed?

First, we used our algorithms to gather as much reliable data as we could about these products. To verify all the data gathered, we used both artificial intelligence and a lot of algorithms.
Then, our experts used criteria that are recognized in the business to evaluate them according to their quality to price ratio, allowing us to choose the top lysine for cats on the market right now!

The selection of the goods is not arbitrary. Before creating a list, we take into account a number of factors. Below are some of the criteria discussed:

Brand Value: What happens if you choose a dubious brand just because it appears to be a good deal? So the likelihood of receiving a product with a short shelf life increases. That is due to the fact that well-known brands have a reputation to uphold, while others do not. Top lysine for cats brands strive to provide some distinctive traits that set them apart from the competition. So, hopefully one or more of the items on our list will be perfect for you.

Features: Useful features are all you need, not tons of them. We consider the important aspects and select the top lysine for cats based on those.

Specifications: Numbers always help you measure the quality of a product in a quantitative way. We try to find products with higher specifications, but with the right balance.

Quality: A product’s quality may always be quantified with the aid of numbers. We look for goods with better standards that strike the proper balance. The best quality product that gets highly appreciated and recommended by experienced users.

Customer ratings:  Would it be accurate to suggest that the lysine for cats were used by hundreds of customers before you? Superior ratings indicate that many customers had better service.

Customer Reviews: Like ratings,  provide you with accurate and reliable information about the product from genuine customers. Customer ratings are very important to all of us because they contain accurate and reliable information about the customer service we received from several hundred customers.

Seller Rank: This is very intriguing! Not only do you need a good lysine for cats, you also need a product with rising sales that is trendy. It accomplishes two goals. First, the expanding user base proves the quality of the product. Second, given that number, producers must be able to offer greater quality and after-sales support.

Value: You get what you pay for, they say, so consider the value. Cheap isn’t always good and expensive isn’t always bad. However, that does not imply that spending a lot of money on a product that is flashy but underwhelming is a good idea. Before adding them to the list, we make an effort to evaluate how much value you can get for your money from your lysine for cats.

Durability: Durability and reliability are closely related concepts. You will benefit from a strong and long-lasting lysine for cats for months and years to come.

Product availability: Products come and go, and new ones replace the old ones. Most likely, a few new features and required changes were made. What use is it to use a supposedly good product if the maker no longer supports it? We make an effort to highlight products that are current and offered by one or more trustworthy sellers, if not more.

Negative Reviews: Yes, we do take that into account as well! The goods with the majority of bad reviews are filtered out and disregarded when we choose the best-rated one on the market.

These are the standards by which we selected our lysine for cats. Do we end our process there? Hell no. The most crucial fact about us that you should be aware of is that we regularly update our website with current and pertinent information. We have one more layer of filtration since we place the greatest importance on reader satisfaction. Please let us know if any product included here is incorrect, irrelevant, subpar, or simply out of date. We always value your opinions, and we’ll work hard to make any necessary corrections to our list in response to them.

Why should you believe us?

There are now thousands of possibilities for these products on Amazon, but choosing the best one can be difficult and time-consuming. And what lysine for cats should you purchase in 2022?

This guide is the result of more than 10 years of experience in researching, testing and writing about many topics. Each member of our team is an authority in their area. We read every article we could find online and every consumer review on every retail website for seven hours. Additionally, we discovered a ton of websites that offered helpful resources, including buying tips and thorough information on lysine for cats.