Dietary supplements are widely used by pet parents around the world. They are sold in pet stores, online, and even in veterinary hospitals. Many companies have capitalized on these trends, and many more have come into being specifically because the pet supplement market is so hot. It is important for pet owners to understand what supplements are, how they are regulated, and what to watch out for when buying pet supplements. 

What are supplements?

The FDA defines a dietary supplement as “a product taken by mouth that contains a ‘dietary ingredient’ intended to supplement the diet. The ‘dietary ingredients’ in these products may include: vitamins, minerals, herbs or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandulars, and metabolites.”

It is important to note that supplements (for pets or humans) are not medications, and they are not proven to treat, cure, or prevent disease. Very few supplements on the market are actually backed up by scientific research and peer-reviewed data showing that they initiate certain desired effects.

Despite the lack of evidence for most supplements, many people take supplements, and many give them to their pets as well. Common pet supplements are used for adding nutrients to the diet (such as vitamins and minerals), supporting health (such as digestive system, skin, or joint health), or influencing behavior. Pet owners may choose to give their pets supplements over traditional medications, believing them to be more “natural” or safer than drugs (though this is usually not the case).

Regulation of supplements

Due to the fact that supplements are not proven to treat or prevent disease, they are not regulated as strictly as are drugs. The FDA regulates drug production, labeling, and distribution. However, for dietary supplements, they only regulate labeling; i.e., a company can produce and sell supplements as long as the label meets a few labeling requirements (name of product, ingredients list, name of manufacturer, and net contents of package).

The FDA does not need to “approve” a supplement for efficacy or safety before it goes on the market. It is expected that the manufacturer performs their own safety studies on their supplements before they sell them. Once on the market, the FDA must prove the product to be unsafe and before restricting their sale. However, supplements are generally not tested once they are on the market; instead, the FDA relies on consumer reports of adverse effects from these products. The FDA also watches for labels containing misleading or false claims (for example: “This supplement cures cancer!”). All supplements with health claims should include a disclaimer, like the ones shown below.

These issues with regulation are why supplements are often considered to be “unregulated.” It is the responsibility of the manufacturer to create a safe and effective product with virtually no oversight from regulatory bodies. If the product is generally safe (in that it doesn’t harm or kill the people eating it), it can be sold, regardless of whether it produces the desired or advertised effects.

It is important to note that the regulations mentioned above only apply to human dietary supplements. The regulation of pet dietary articles varies based on specifics in their intended use. The supplements pet owners obtain at pet stores or online are regulated similarly to pet foods, because the FDA does not define “animal dietary supplements.” Therefore, they only need to meet a few food labeling requirements (see How to read a pet food label for more information). Enforcement of regulations on pet supplements by the FDA is often even poorer than for human supplements .

The National Animal Supplement Council (NASC) is an organization that promotes the safe use of pet supplements. They work together with national and state regulatory agencies to create a regulatory environment with a consistent, fair, and responsible foundation. The NASC offers membership to pet supplement manufacturers, and provides the NASC Seal of Quality to manufacturers who uphold their Good Manufacturing Practice Quality Standards. These standards are much more rigorous than the FDA’s or state regulation of pet supplements.

The NASC Seal of Quality

Things to consider

There are many things to keep in mind if you are considering buying supplements for your pet.

Veterinarian’s recommendations

If your pet’s usual veterinarian recommends a supplement, be sure to get the brand name, dose, and specific instructions for supplementing from them. There are some veterinarians who may specialize in this topic, such as board-certified veterinary nutritionists. Your pet’s usual veterinarian should be able to put you in touch with an expert if they are unable to give specific recommendations.

Even if your pet’s veterinarian did not recommend supplementing their diet, you should always let them know about all the supplements you feed your pet. Dietary supplements can impact treatments for certain illnesses, and they may even cause illness themselves if administered inappropriately.


Supplements are required to have an ingredient list on their label. It is always important to look at the label of supplements and treats to see if they contain toxic or harmful ingredients. Be sure to look at not only the active ingredients, but the inactive ingredients and additives as well, especially if the supplement is made for humans. For example, multivitamin gummies may contain xylitol, which is toxic to pets. For a list of unsafe foods, check out What not to feed: unsafe foods for pets.

It is important to note that some things may be in the supplement that are not listed on the label, like contaminants. Contaminants can get into the product during the manufacturing process, especially if they are made in a factory that produces other types of supplements or feed additives. The only way to know if the product is free of contaminants is to purchase supplements from manufacturers that have strict quality control.

Calorie statement

Though not typically found on supplement labels, pet supplements should contain a calorie statement. Be sure to take those calories into account with your pet’s total daily caloric intake, as calories from food, treats, and supplements can add up quickly! (Visit How to calculate your pet's calorie needs for more information.)

Dose or dosage

Most supplements do not have adequate research showing they produce desired effects. Therefore, determining a dosage (amount of supplement per unit of pet’s body weight) for a given supplement is nearly impossible. However, many supplements labels will instruct you to give a certain dose (total amount of supplement per serving). It is important to take note of that dose, and not to exceed it. The dose given on the bottle is a dose that should not produce adverse effects (i.e., it is a “safe” dose). Exceeding the instructed dose may lead to adverse effects, depending on the type of supplement. Additionally, giving multiple supplements with the same ingredients could lead to overdose, so it’s best to stick with a single supplement. 

Homemade diets

Nutrient supplements are usually necessary when a pet is eating a homemade diet. Homemade diets and balancing supplements should only be fed under the supervision of a board-certified veterinary nutritionist. The nutritionist will design a diet that meets your pet’s needs and provide you with specific nutrient supplements, along with doses and instructions for feeding.

It is important to note that dietary supplements will not replace or compensate for an unbalanced diet. It is unsafe to feed a homemade diet without the guidance of a board-certified veterinary nutritionist, even when using nutritional supplements. To learn more, visit Homemade diets.

Cost-benefit analysis

As stated previously, most supplements are not proven to produce desired or advertised effects. Furthermore, if your pet is eating a commercial complete and balanced pet food that is labeled for their species and life stage, supplements are often unnecessary. Therefore, supplementing your pet’s diet is often a waste of money, unless their usual veterinarian has given you a specific supplement recommendation and instructions.

How to find a reputable manufacturer

Not all pet supplement companies are created equally in terms of quality. Finding a supplement manufacturer that is reputable, reliable, and based in science is time-consuming and requires you to “do your homework” before buying. Because supplements are regulated so poorly, you will want to be sure to buy from a company that regulates itself well. The following suggestions are similar to selecting a good pet food company (see How to pick a pet food, part 1).

Reputable supplement manufacturers should employ veterinarians and work with veterinarians outside the supplement industry. Some companies are even veterinary-specific; i.e., you can only purchase supplements through your pet’s usual veterinarian. Good supplement manufacturers will uphold stringent quality control for their raw ingredients, formulating and manufacturing procedures, and analysis of end products (including consistency between label and actual contents) . They will also perform and publish scientific research, namely safety studies (is the product safe for the species at certain dosages?) and efficacy studies (does the supplement produce the desired effect on the animal at a certain dosage?). It might also be a good idea to check that the product contains the NASC Seal of Quality on the label.

Nutrient supplements

These supplements are intended to provide nutrients to the diet. Nutrients include things like protein, fat, fiber, vitamins, and minerals. Dogs and cats each have unique dietary requirements for over 40 different nutrients (to learn more, visit Nutrient requirements.) It is important to note that if your animal is healthy and is eating a commercial complete and balanced diet that is formulated for their species and life stage, feeding them nutrient supplements is unnecessary and not recommended. Over-supplementing nutrients like vitamins and minerals can have detrimental consequences for your pet.


Most protein or amino acid supplements are given as health supplements rather than nutrient supplements. See the next section for details. Feeding extra protein (more than what the pet actually requires) is unnecessary, and will result in protein wasting in the urine. 


Fat supplements are usually just oils that are drizzled on the food, and are often used to help pets gain weight (as fats are very energy dense). Fatty acid supplements are typically used for things like skin and coat health or joint health. See the next section for details. Feeding too much fat can cause weight gain, pancreatitis, greasy stool, and other digestive upset.


Fiber is tricky because there are different types of fiber, each of which has different effects. Some types of fiber bulk up the stool, while other types of fiber loosen the stool. Many ingredients contain different ratios of both types of fiber. If your pet’s stool is too loose or too hard, talk to their veterinarian before adding a fiber supplement to their diet. (Learn more about abnormal stool at Assessing your pet’s poop.)


There are two classes of vitamins: fat-soluble and water-soluble. Fat soluble vitamins (A, D, E, and K) are more likely to become toxic because they are stored in the body fat. Therefore, fat soluble vitamins should not be supplemented without the direct supervision of a veterinarian. Water soluble vitamins (B and C) are unlikely to become toxic because they are excreted in the urine. Most water soluble vitamins are made in the body and do not need to be supplemented if the animal is healthy.


The balance of minerals in the diet is crucial. Minerals are required by the body in very specific amounts, and changing the ratios of minerals through supplementation can have severe health consequences.


Vitamin and mineral supplements may also come in premixes. Premixes will have specific ratios of vitamins and minerals, and are usually intended to be added to a homemade diet. Homemade diets and premixes should only be used under the direct supervision of a board-certified veterinary nutritionist. To learn more, visit Homemade diets.

Health supplements

These supplements are intended to support one or more aspects of pet health. There are many types of health supplements, each containing different ingredients and nutrients. However, most health supplements do not have scientific research substantiating the claims made on their labels. 

Skin & coat

Skin and coat supplements are often used for pets who have dry skin, dull hair coats, hair loss, or itchiness.

Omega fatty acids

These are often a key component of skin support supplements. It is important to note that the Omega (Ω) fatty acids do not cure skin disease, but they may help the body repair damage to the skin. Ω-3 and Ω-6 fatty acids are nutrients that are essential for skin and coat health. Ω-3s also have great anti-inflammatory properties which can help itchiness and redness. The ratio of Ω-3 to Ω-6 is very important: pets should be getting more Ω-3s than Ω-6s. 

Adult dogs and cats require alpha-linolenic acid (an Ω-3) and linoleic acid (an Ω-6) in their diets. Adult cats also require arachidonic acid (an Ω-6), which is found only in animal fats.  Commercial complete and balanced diets which are formulated for adult dogs or cats will contain sufficient amounts of these nutrients.

Growing, pregnant, and lactating animals also require eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the other two Ω-3 fatty acids. Commercial complete and balanced diets formulated for pregnant and lactating mothers will contain sufficient amounts of these nutrients, in addition to those described above.

Typically, supplemented fatty acids will include high proportions of EPA and DHA. Good sources of these Ω fatty acids include fish oils; plants like flax and corn are not the best source of EPA and DHA. Coconut oil is a very poor choice for supplementation: it only contains a tiny percentage of linoleic acid (an Ω-6), and none of the Ω-3s.


Biotin is a B-vitamin that is important for skin, coat, and nail health. You may find some skin support supplements contain biotin. Biotin is a non-essential nutrient because it is made in the animal’s body. As with the Omega fatty acids, biotin will not cure skin disease, but it may help the body repair damage to the skin.


This mineral may be found in some skin support supplements. Zinc is an integral part of protein formation in the skin and coat. Commercial complete and balanced diets contain sufficient zinc, so animals should not need zinc supplementation unless they are a predisposed breed (such as the Siberian Husky) or have zinc deficiency. Zinc supplements are often poorly bioavailable (not absorbed or used well by the body).

Vitamin A

This vitamin plays an important role in maintaining skin health. Commercial complete and balanced diets contain sufficient vitamin A. Supplementing vitamin A should only be done under the direct supervision of a veterinarian, as it can lead to toxicity.


Joint support supplements are the most widely used specific supplement by dog owners. They contain many different ingredients and nutrients that are intended to prevent joint breakdown, aid in tissue repair, and decrease inflammation. 

Omega fatty acids

Omega-3 fatty acids are the only supplements that have been proven through scientific research to be effective in managing joint disease. The Ω-3 fatty acids EPA and DHA are a key component of joint health. They have significant anti-inflammatory properties, and therefore reduce tissue damage and associated pain. Refer to the “Skin and coat” section for additional information about Ω-3 fatty acids.

Green-lipped mussel

This ingredient is becoming more popular as a joint supplement. It contains many nutrients, including Omega-3 fatty acids, vitamins, and minerals. Green-lipped mussel has been shown to alleviate pain and improve function in arthritic animals, but this may simply be due to the high proportions of Ω-3 fatty acids.

Collagen & hyaluronic acid

These compounds are found in joints and contribute to the health and structure of the joint. Some studies have demonstrated that supplementation with certain types of collagen and hyaluronate may be effective for supporting joint health in dogs, and can also help decrease inflammation.

Glucosamine & chondroitin

These are often a main component of joint support supplements as well. These compounds are part of the structural makeup of joints, which is why they are used as a supplement for joint health. However, there is no scientific evidence showing glucosamine and chondroitin supplementation prevents arthritis. There is also no evidence showing they are any better than a placebo at controlling existing joint pain and inflammation.


Methylsulfonylmethane (MSM) is an agent widely used for its anti-inflammatory properties. However, there is little to no research suggesting that MSM is beneficial for managing arthritis or joint pain in dogs.


Supplements targeting muscle and bone health are very popular among working, agility, and other sporting dogs. These supplements often aim to strengthen bone, decrease muscle loss, and improve muscle gain. However, there is no evidence to suggest that healthy working dogs require supplementation of protein, vitamins, or minerals. As long as they are eating the correct amount (right number of kcals) of a complete and balanced diet, they will take in proportionally more nutrients to fulfill their needs.

Calcium & phosphorus

These minerals are often found in musculoskeletal supplements to help strengthen bone. Many people claim that “bones can never be too strong.” However, supplementing calcium and phosphorus can have detrimental side effects, including causing the bones to become too soft or too brittle. This can lead to developmental bone disease in growing animals, or breaking of bones in adult animals. Refer to the minerals table in the “Nutrient supplements” section for more information.

Protein & amino acids

These nutrients are in musculoskeletal supplements with the intent of building muscle and preventing muscle loss. You may commonly see whey, creatine, and carnitine in canine protein supplements. However, if a dog is eating the right amount of a commercial complete and balanced diet, he should not require protein supplementation. Additional protein not used by the body will be wasted in the urine.


As exercise intensity increases, oxidant stress and muscle damage also increase. Antioxidants are beneficial for decreasing the damage caused by inflammation. Some believe working pets require supplemented vitamin E or other antioxidants. However, there is no scientific evidence to support this; frequent exercise is actually better than adding antioxidants to the diet.


This is a new product that is used to decrease muscle loss in dogs who are not using their muscles (called disuse muscle atrophy). A recently-published scientific study shows that this product holds promise.

This is not an advertisement.


If your pet has heart disease, please speak to their usual veterinarian before you buy any supplements. Supplements are not proven to treat or cure heart disease, and they may interfere with heart medications prescribed by the veterinarian 

Omega fatty acids

The Ω-3 fatty acids have been widely used to manage patients with heart disease. However, there is no research showing that supplementation of Ω-3s alone is effective in treating heart disease in dogs, nor has an optimal dosage been described in the literature.

Taurine & cysteine

These are the main components of many cardiac supplements. Taurine is an amino acid that is important for heart muscle health. Dogs can make taurine in their bodies from its precursor cysteine. Cats require taurine to be in their diets because they cannot make it from cysteine. Dog foods do not need to contain these two amino acids, but commercial complete and balanced cat foods will always contain sufficient taurine. Taurine alone has not been proven effective in treating heart diseases other than taurine-deficient dilated cardiomyopathy (DCM) in cats.

Whey, creatine, & carnitine

These protein and amino acid sources may be seen in heart supplements as well. Again, these are commonly intended to build muscle and prevent muscle loss. However, there is no scientific evidence showing supplementation with these products alone benefits patients with heart disease.


Supplements that support the digestive system can be broken up into smaller categories based on the specific part of the system they are intended to target. 


Oral and dental care supplements usually come in the form of a treat, chew, or water additive. However, very few of the products on the market have been proven to be beneficial for oral health. For more information on these products, check out The importance of oral health.

It is important to note the ingredients on products you buy. If an oral health supplement contains fluoride, you will need to make sure you do not feed more than the recommended dose, as fluoride poisoning can cause severe dental and bone disease (see the Nutrient Supplement section above for more information).

Hairball control


Papayas contain an enzyme called papain, which is found in many feline hairball control supplements. There is no scientific research showing that this enzyme alone is effective in managing hairballs in cats.


Many hairball supplements will contain some sort of insoluble fiber which acts as a laxative and digestive lubricant. There is some scientific evidence showing that sugarcane fiber may prevent hairball formation in cats. However, more research needs to be done on this topic.

Omega fatty acids

Often, hairball prevention supplements will contain Ω-3 fatty acids to help support skin and coat health. Refer to the “Skin and coat” section above for more information.

Digestive enzymes

Many organs in the digestive system produce enzymes to help break food ingredients down into nutrients that the body can use. Enzymes are sufficiently produced by the stomach, pancreas, liver, and small intestine in normal, healthy animals. If your pet has been diagnosed with a health condition that causes them to need supplemental digestive enzymes (e.g., exocrine pancreatic insufficiency), ask their usual veterinarian for a specific product and dose recommendation. Without the diagnosis of a specific health condition by a veterinarian, enzyme supplements are absolutely unnecessary. 



S-adenosylmethionine is the active form of an amino acid called methionine. Methionine helps guard against cell damage in the liver, which is why it is found in many liver supplements. However, there are only a few very limited studies showing SAMe’s effectiveness for treating dogs and cats with liver disease.

Milk thistle

Extract from the plant Silybum marianum is widely used in pet liver supplements for its purported anti-inflammatory, antioxidant, and hepatoprotective effects. A few scientific studies have been performed looking into the efficacy of milk thistle supplementation in dogs and cats with liver disease. These studies are limited, but do show promise for this supplement.

Probiotics & prebiotics

Trillions of bacteria live in our pets’ large intestines and aid in digestion. They ferment things the animal wouldn’t normally be able to digest, such as fiber and other plant materials. These microbes also help regulate metabolism, nutrient absorption, and immune function. Normal healthy animals have a diverse range of microorganisms living in their guts, but illness, certain medications, and stress can all disrupt the gut bacterial balance. Disruptions in the gut microbiome may lead to loose stool, flatulence, or even a weakened immune system.

Probiotics are intended to introduce healthy bacteria back into the pet’s digestive system after an event like illness or stress. Many probiotic supplements are on the market today, and some pet foods may even contain these organisms. There are hundreds of different types of bacteria that live in our pets’ digestive tracts, and they are all specific to the species in which they reside; therefore, dog probiotics will not work for cats, and vice versa. Each species of bacteria also requires a specific number of colony forming units (CFUs) to be effective; this number is based on scientific research.

Like with every supplement, not all probiotics are created equally. An effective probiotic product must contain live and viable microbes when it is eaten, it must be resistant to digestion in the stomach or small intestine, it must be safe, and it must contribute to a balanced and healthy microbiome in the pet. A probiotic manufacturer must perform quality testing and research to ensure their product is safe and effective. Unfortunately, most companies do not do this.

Prebiotics are essentially food for probiotics; they contain materials such as fiber which the gut bacteria can ferment and use for energy. Prebiotics help the gut bacteria thrive and are therefore an essential component of gut health. Prebiotics are often combined with probiotics to make a product called a synbiotic. 

Immune function

The immune system is a complex and ever-changing network of cells and chemical messengers with many roles. These cells and messengers guard against, target, and destroy foreign and disease-causing pathogens. The best way to ensure your pet’s immune system gets the nutrients it needs is to feed the right amount of a complete and balanced diet that is appropriate for the animal’s life stage, and keep them in ideal body condition.

Vitamin C

This nutrient is commonly found in immune support products for us and our pets. Dogs and cats do not require Vitamin C to be in their diets; they can make it in their bodies. At low doses, Vitamin C can be a beneficial antioxidant, which is why it is often found in immune supplements. However, over-supplementing vitamin C may lead to inflammation and even bladder stones. Therefore, it may be best to avoid supplementing vitamin C unless your pet’s veterinarian specifically recommends it.

Vitamin E

This nutrient is an important antioxidant and may be found in immune supplements. There is some scientific evidence showing that moderate supplementation improves numbers of immune cells in cats. However, further research is needed.


This ingredient may be found in immune support supplements. Beta-carotene is a precursor of vitamin A, a nutrient that plays an important role in immune cell function. Some studies have shown that moderate supplementation with beta-carotene improves numbers of immune cells in dogs, but further research is required.


This ingredient is found in many immune support products. Colostrum is the first milk a mother provides to her newborns. It contains high amounts of fat, protein, and immune proteins called immunoglobulins. Protein, fat, and other nutrients are important for neonatal nutrition. Immunoglobulins confer passive immunity to the newborn when ingested in the first day of life. After this window closes, the gut is no longer able to absorb the complete proteins. It is well understood in the scientific community that colostrum is of the greatest benefit to neonatal animals.

While colostrum will not confer immunity to adult animals, it may still provide some benefit. There is one study showing that supplementing adult dogs improves immune response to vaccines. This may be due to the high amount of protein, fat, vitamins, and other nutrients found in the colostrum. More research is needed to determine if colostrum supplementation positively affects immune function in adult animals.


Allergy relief supplements often contain many different ingredients, most of which have already been mentioned. In dogs and cats, allergies typically manifest in the skin, causing itchiness, scratching, redness, hair loss, and swelling. Sometimes, allergies may manifest in the digestive system and cause vomiting and diarrhea. To learn more about allergies, particularly to food, visit Food allergies.

Skin support

Many allergy supplements contain the same nutrients and ingredients found in skin support supplements. Refer to the “Skin and coat” section above for more information.


Probiotics are also popular supplements for allergy relief. They have traditionally been used to alleviate digestive symptoms, but certain strains of bacteria may benefit patients with skin disease. See the “Gastrointestinal” section above for more information.


This ingredient may be found in allergy relief supplements with the intent of stimulating the immune system. However, allergies are actually the result of an overactive immune system, so colostrum may not be the best choice for these pets. See the “Immune function” section above for more details.


Urinary system support is an important consideration for many pet owners. Kidney disease and bladder stones are common ailments of dogs and cats. If you suspect your pet has urinary issues, they should be seen by a veterinarian right away. Usually, kidney disease and bladder stones are best managed by a therapeutic diet (learn more here). Always consult with your pet’s usual veterinarian before feeding any urinary support supplements.

Hydra Care®

This is a new hydration supplement for cats. The product comes in liquid form and contains protein, electrolytes, and fiber. Research shows that consumption of this supplement helps cats drink significantly more water throughout the day, which is important for maintaining kidney and urinary health, especially in cats with kidney disease or bladder issues.

This is not an advertisement.

Omega fatty acids

Research has shown that dietary supplementation with Ω-3 fatty acids is beneficial for canine patients with kidney disease, while supplementation with Ω-6 fatty acids caused more kidney damage. To learn more about Ω fatty acids, see the “Skin and coat” section above


There are conflicting studies suggesting that cranberry consumption may be beneficial for humans with urinary tract infection. However, there are currently no studies showing their benefit for dogs or cats.


There are studies suggesting that consumption of this sugar may prevent urinary tract infection in women. However, there are currently no studies showing the benefits of D-mannose for dogs and cats.

Urine acidifiers or alkalizers

Certain types of bladder stones and crystals form at either alkaline or acidic pH. Acidifiers or alkalizers may be used to change urine pH to make it lower or higher, respectively. However, feeding these products to your pet without the supervision of a veterinarian can be extremely dangerous and may cause their disease to become worse. If your pet has been diagnosed with bladder crystals or stones, talk to their veterinarian about the best course of action.


There are many supplements on the market that are intended for pregnant and lactating animals. They may contain protein, vitamins, minerals, herbs, or other ingredients. 

It is important to note that all pregnant and lactating mothers should be eating a commercial complete and balanced food that is formulated for reproduction. These diets will contain sufficient nutrients to get bitches and queens through pregnancy and lactation. Healthy animals eating a commercial complete and balanced pet food do not require nutrient supplementation.

One nutrient in particular may cause significant harm to animals after giving birth. This nutrient is calcium, a macromineral that is required in very specific amounts (see “Nutrient supplement” section for more information). Feeding too much calcium during pregnancy has been shown to contribute to postpartum hypocalcemia (also called eclampsia) in the bitch. This is a life-threatening emergency condition for the mother. It is very important that pregnant mothers do not receive calcium supplementation. 

Behavioral supplements

There are many behavioral supplements on the market. Some are intended to treat anxiety, while others are meant to help cognitive function. Therapeutic calming and aging diets are available as well (to learn more about therapeutic diets, click here). The supplements mentioned here are not an exhaustive list; they are merely some of the more commonly used products. It is important to note that all animals are unique behaviorally and mentally, and therefore responses to different supplements may vary widely. 

Calming care

This is a probiotic supplement made from a strain of human microorganisms called Bifidobacterium longum. Supplementation with this probiotic has shown to decrease anxiety behaviors in research dogs, as well as decreasing heart rate and cortisol levels (a hormone associated with stress).

This is not an advertisement. 

Omega fatty acids

Omega-3 fatty acids are truly important for so many body functions. In addition to helping our pets’ skin, coat, and organ function, research has also shown that Ω-3s also decrease anxiety in pets. For more information about Ω-3s in general, see the “Skin and coat” section above.


This is an essential amino acid for dogs and cats, meaning they cannot make it themselves so it must be present in their diets. Tryptophan is important for many cellular processes in the body, including neurotransmitter synthesis. Studies have shown that supplementing tryptophan along with other nutrients helps decrease fearful behaviors in dogs and cats.


Several calming supplements and therapeutic diets for dogs and cats contain components of colostrum. Hydrolyzed casein (a protein) is the nutrient of focus for behavioral supplementation of colostrum products. There are limited studies suggesting that casein supplementation is effective in treating anxiety disorders in dogs and cats. However, more research is necessary.


This amino acid can bind to certain receptors in the brain. Studies have shown that L-theanine decreases fearful behavior in dogs. Studies suggest that supplementation of L-theanine may improve behavioral signs of stress in cats, but more research is needed for felines.


Gamma-aminobutyric acid (GABA) is a neurotransmitter involved in inhibiting nerve signals in the brain. GABA is also available as a supplement for pets and humans. There is some research suggesting that GABA supplementation may improve behavioral problems associated with old age in dogs, but more research is needed. 


This naturally occurring hormone has influences on sleep cycles and seasonal activity in many animals. However, despite its wide use as a supplement, there is no scientific evidence showing that melatonin has any calming or sedative effects on anxious dogs or cats.

Other supplements

Food toppers

Some people use the term “supplement” to describe food toppers. Food toppers are added ingredients that are used to “top off” a pet’s regular diet. These toppers are usually not complete and balanced, and therefore care should be taken when adding them to the diet to prevent nutrient imbalances. To learn more, visit Treats, table scraps, and food toppers


Cannabis products, namely CBD oil, are immensely popular supplements for both pets and humans. CBD pet product manufacturers claim their products have calming properties, can alleviate pain, treat epilepsy, help fight infection, and much more. However, there is no current scientific evidence supporting these claims.

Currently, there is a single approved drug (Epidiolex) containing CBD that has been proven to treat human epilepsy. According to the FDA, cannabis is a drug and is therefore not generally recognized as safe (GRAS) for animals or humans. Therefore, pet products containing CBD are considered adulterated by the FDA, and their sale is illegal. The FDA states: “Selling unapproved products with unsubstantiated therapeutic claims is not only a violation of the law, but can also put patients at risk, as these products have not been proven to be safe or effective.” However, the FDA does not have the time or manpower to dedicate to policing the issue.

Technically, veterinarians are not supposed to discuss cannabis with clients, suggest it, or distribute it. Unless a veterinarian is prescribing Epidiolex to pets to treat epilepsy, veterinarians should not be suggesting cannabis products to their clients. Regulations differ between the state and federal levels, so it is important for veterinarians to keep up on developments. If the FDA and veterinary medical boards decide to begin cracking down on this issue, veterinarians would be risking their licenses even talking about cannabis products with clients.

Herbal blends

Blends of plants or herbs are widely used as supplements for a variety of purposes in homeopathic and alternative medicine. However, there is little to no evidence that they work for humans, and even less evidence they work for animals. It is also important to note that some plant ingredients found in these supplements can be toxic to dogs and cats, so always read labels and check the ingredients. It may be best to simply stay away from these unproven supplements.

Essential oils

Not much is known about essential oil safety. Essential oils are not regulated by the FDA, so manufacturers do not have to back up any claims they make. Many essential oil manufacturers and distributors claim that oils can cure, prevent or treat disease. These claims have not been evaluated by the FDA, and therefore essential oils should never be used as medication. Additionally, as safety studies have not been performed for the majority of essential oils, they should never be ingested by anyone, human or animal. Various different essential oils can be toxic to pets, whether they are applied to the skin, inhaled, or ingested. Essential oil poisoning can cause skin and digestive irritation as well as nervous system depression. It is safest to not use essential oils on or around your pet.


This article is intended to be informational; it is not an advertisement for any products or diets. The author is not paid to promote any products or diets mentioned in this article. The author is not a salesperson, nor is she employed by any pet food or supplement companies.


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