The Complete Guide to Supplements for Dogs and Cats

Owner petting dog and cat while sitting on the couch

Key takeaways

Supplements can play a meaningful role in supporting your pet’s health, particularly for joint mobility, digestive balance, skin and coat condition, and overall wellness
Fish oil has the strongest research support of any supplement category for pets, with benefits spanning joints, skin, coat, and general wellbeing
Joint supplements are the most widely used category, and many pet parents report positive results when used consistently
Probiotics may help support normal digestive function, especially during diet transitions, stress, or antibiotic use
Look for products bearing the NASC (National Animal Supplement Council) quality seal as a sign of ingredient accountability and manufacturing standards
Talk to your veterinarian before starting supplements if your pet is on medication, since some interactions are possible

More pet parents than ever are thinking proactively about their pet’s health, and supplements have become a meaningful part of that conversation. Whether you’re looking to support an aging dog’s joints, help a cat with sensitive skin, or maintain your pet’s overall wellbeing, the right supplement, used consistently, can be a worthwhile addition to their routine.

This guide walks through the major supplement categories, what they’re used for, and how to choose well. As with any change to your pet’s health routine, your veterinarian is a good resource, especially if your pet has an existing health condition or takes medication.

When supplements are most useful

Supplements are versatile. Some are well-suited for everyday use across a pet’s life, while others are most valuable at specific life stages or during particular situations.

Aging pets: As dogs and cats get older, joint mobility, digestive efficiency, and skin condition can all shift. Supplements targeting these areas are among the most commonly used and most consistently appreciated by pet parents of senior animals.
Active and large-breed dogs: Dogs with high activity levels or breeds predisposed to joint concerns may benefit from proactive joint support, even before any stiffness is apparent.
Pets going through transitions: A diet change, a move, boarding, or a new household member can all affect digestion and stress levels. Probiotics and calming supplements are both useful tools during these periods.
Skin and coat support: Pets with dull coats, occasional skin dryness, or sensitivity may see meaningful improvements with targeted fatty acid supplementation.
Pets on non-standard diets: Animals eating homemade or non-commercial diets may have nutritional gaps that a well-chosen supplement can help address.

Common supplement types

Joint supplements

Joint supplements are the most widely used category in pet health, and for good reason. They’re most commonly used in older dogs but are increasingly given to younger large-breed dogs as a proactive measure.

Glucosamine and chondroitin are the foundational ingredients in most joint formulas. These naturally occurring compounds are found in cartilage and may help support joint function, healthy cartilage, and normal mobility. Many pet parents report meaningful improvements in their dog’s comfort and activity levels with consistent use. Fish oil, which is covered in its own section below, is also a well-supported addition for joint health. Green-lipped mussel is another ingredient with research supporting its use in dogs.

For cats, research in joint supplementation is still developing, and cats metabolize many compounds differently than dogs. If your cat is showing signs of reduced mobility or stiffness, that’s worth discussing with your vet, who can guide you on appropriate options.

The full picture of supporting hip and joint health in dogs, including the important role weight management plays alongside supplementation, is worth a read.

Fish oil and omega-3 fatty acids

Fish oil is arguably the most broadly beneficial supplement you can add to a dog or cat’s routine. The long-chain omega-3 fatty acids it contains, EPA and DHA, may help support healthy skin and coat condition, normal joint function, and overall wellbeing. It’s the supplement category with the strongest body of research in companion animals, and it’s well tolerated by most dogs and cats.

For cats in particular, omega-3 fatty acids may help maintain normal skin health and support a healthy coat. Cornell University College of Veterinary Medicine notes that the combination of omega-3 and omega-6 fatty acids may help support normal skin function and reduce occasional itching by replenishing the skin’s essential oils.

When choosing a fish oil product, look at the EPA and DHA content specifically rather than total oil volume, since products vary significantly in concentration. Follow the label directions for dosing, as the right amount depends on your pet’s weight.

Probiotics

Probiotics are beneficial microorganisms that may help support a healthy balance of gut bacteria. They’re one of the more practically useful supplement categories because the situations where they help are common ones: a course of antibiotics, a food transition, boarding or travel, or bouts of occasional digestive upset.

Probiotics may help support normal digestive function and help maintain proper gut flora, particularly during periods of change or stress. Some pet parents give them consistently as part of a long-term wellness routine; others reach for them situationally. Both approaches have merit depending on the pet.

Quality matters more with probiotics than almost any other supplement category. A good probiotic label includes an expiration date, the specific bacterial strains present, and a guaranteed count of live organisms at the time of use. Look for products that have been studied in dogs or cats specifically.

Calming supplements

Calming supplements are designed to help pets maintain a normal, relaxed disposition during situations that may feel unsettling, such as travel, thunderstorms, fireworks, boarding, or changes in household routine. Common ingredients include L-theanine, melatonin, and various botanicals.

These supplements work best as a proactive tool, given before a stressful event rather than in the middle of one. Many pet parents find them useful for predictable situations where their pet tends to feel unsettled. For cats with more persistent anxiety, how to help calm your cat’s anxiety covers a broader range of environmental and behavioral approaches that work alongside supplementation.

Multivitamins

Multivitamins are broadly formulated to cover multiple nutritional bases in a single product. They’re particularly well suited to pets on homemade diets, picky eaters who may not be getting consistent nutrition, and senior pets whose nutritional requirements shift with age.

Life stage matters here. Senior dogs and cats often benefit from targeted supplementation as their bodies change, and a well-formulated senior multivitamin can help fill those gaps. For pets eating a nutritionally complete commercial diet and in good overall health, the benefit of adding a multivitamin is more modest, though there’s no harm in choosing one formulated appropriately for your pet’s age and size.

One important note: never give a pet a human multivitamin. Several ingredients commonly found in human supplements, including certain forms of vitamin D, iron, and alpha-lipoic acid, are not safe for dogs and cats.

Skin and coat supplements

Skin and coat supplements typically center on omega-3 fatty acids, biotin, zinc, and vitamin E, all of which play a role in maintaining normal skin integrity and coat condition. For dogs and cats with dull coats, dry skin, or heavy shedding seasons, a targeted skin and coat supplement may help support healthy coat texture and normal skin function.

Results with this category are often visible. A coat that’s shinier, less dry, or sheds more normally is a meaningful quality-of-life improvement for both the pet and the household. That said, if your pet’s skin or coat has changed suddenly or significantly, a vet conversation is worthwhile, since underlying causes like allergies or parasites sometimes need to be addressed directly.

How to choose a quality supplement

With a wide range of products available, a few markers help identify the ones worth reaching for:

NASC quality seal: The National Animal Supplement Council audits member companies and requires that their products meet manufacturing and labeling standards. The NASC seal on a product means the manufacturer is held to ongoing accountability for ingredient accuracy and quality.
Clear ingredient quantities: Reputable products list the actual amounts of each active ingredient on the label. Proprietary blends that obscure individual ingredient amounts can make it harder to evaluate what you’re actually giving your pet.
Expiration date and lot number: Particularly important for probiotics, where viable organism counts degrade over time. These details also indicate that the manufacturer tracks products post-production.
Species-specific formulation: A supplement made for dogs is not necessarily safe for cats. Cats metabolize many compounds differently, and some ingredients that are well tolerated by dogs can be harmful to cats. Always use products formulated for your pet’s species.

Supplement formats: what works for your pet

The best format is the one your pet will take consistently.

Soft chews and chewable tablets: The most popular format for dogs. Flavored chews are often eaten directly as a treat, making daily administration easy. If your dog is weight-conscious, check the calorie content per chew.
Powders: Mix easily into food, which works particularly well for cats. Good for pets who won’t take a chew or tablet.
Liquids: Fish oil is commonly given in liquid form mixed into food. Easy to administer and generally well accepted. Check whether the product requires refrigeration after opening.
Capsules and tablets: Sometimes easier to dose precisely. Can be hidden in food or a treat for pets who need a little coaxing.

A few things to keep in mind

Tell your vet what your pet takes. If your pet is on medication, let your vet know before adding any supplement, since interactions are possible. This is especially important for pets managing ongoing health conditions.
Follow dosing instructions. More isn’t always better. Fat-soluble vitamins accumulate in the body over time, and exceeding recommended amounts, even with beneficial ingredients, can cause problems. Stick to label directions unless your vet advises otherwise.
Introduce gradually. When starting something new, give your pet a smaller amount for the first few days. If you notice GI upset or anything unusual, pause and reassess.
Never use human supplements for pets. Some ingredients in human multivitamins and supplements, including certain forms of vitamin D3, alpha-lipoic acid, xylitol, and high-dose iron, are not safe for dogs and cats. Only use products formulated for pets.

Frequently asked questions (FAQs)

My dog seems healthy. Is there still a reason to use supplements?

Yes, depending on what you’re looking to support. Fish oil, for example, is broadly beneficial for skin, coat, and joint health and is a reasonable daily addition for many dogs regardless of age. Joint supplements are increasingly used proactively in large breeds before any stiffness develops. Probiotics are useful situationally around events like travel or diet changes. The right supplement depends on your dog’s life stage, breed, and individual needs.

How long does it take to see results?

It varies by supplement and pet. Joint supplements are typically given for four to six weeks before noticing changes in mobility. Skin and coat supplements may take a similar amount of time to show visible changes in coat quality. Probiotics often work more quickly, sometimes within a few days for digestive support. Consistency matters significantly across all categories.

Can I give my dog and my cat the same supplement?

Not necessarily. Dogs and cats metabolize many compounds differently, and some ingredients that are appropriate for dogs are not safe for cats. Always use species-specific products, and check with your vet if you’re unsure about a particular ingredient for your cat.

What does the NASC seal mean?

The National Animal Supplement Council is a nonprofit industry organization that audits member companies and holds them to manufacturing and labeling standards. Products bearing the NASC quality seal have gone through an independent review process, and the manufacturer commits to ongoing compliance. It’s one of the most reliable signals of product quality and ingredient accountability available in the pet supplement market.

Are supplements safe for senior pets?

Many supplements are particularly well suited to senior pets, whose joint mobility, digestive function, and nutritional needs often change with age. If your senior pet takes prescription medications, check with your vet before adding anything new, since some interactions are possible and organ function can affect how supplements are metabolized in older animals.

Information in this article is not intended to diagnose, treat or cure your pet and is not a substitute for veterinary care provided by a licensed veterinarian. For any medical or health-related advice concerning the care and treatment of your pet, contact your veterinarian.