Selecting supplements for the senior pet

In senior pets, supplements can help to ameliorate pain, mobility, cognitive decline, cancer, and extend quality of life

In senior pets, supplements can help to ameliorate pain, mobility, cognitive decline, cancer, and extend quality of life. Deciding which ones to use, however, can be daunting. Photos ©
In senior pets, supplements can help to ameliorate pain, mobility, cognitive decline, cancer, and extend quality of life. Deciding which ones to use, however, can be daunting.

Several years ago, I had a new patient consult with ‘Bunny,’ a lovely senior husky mix who had recently been diagnosed with end-stage metastatic neoplasia. Bunny’s guardian was primarily seeking guidance on supplements to improve the dog’s quality of life. Unfortunately, the cancer was already quite progressed, and Bunny was euthanized a few days after her first appointment.

The quick progression from initial visit to euthanasia certainly made this case memorable; however, what made the consult truly remarkable was the list of supplements the client had brought in to discuss, which contained no less than 40 options. In the client’s mind, this combination would cure Bunny’s cancer.

While this situation is extreme, it highlights the growing trend of senior-pet owners turning to supplements for a variety of reasons—mainly, to ameliorate pain, mobility, cognitive decline, cancer, and to extend quality of life. Indeed, the business of pet supplements continues to grow exponentially every year. The global pet supplement market in 2020 alone was estimated to be US$1.47 billion and is predicted to increase almost six per cent annually over the next decade. This expansion is likely driven by an increase in adoptions and the growing attitude of pets being embraced as members of the family. With these factors considered, along with the trend of people preferring ‘natural’ or ‘holistic’ options for themselves and their pets, it is no wonder why pet supplements are big business.

Veterinarians and pet owners alike are bombarded with numerous products from large pharmaceutical and pet product companies to small local businesses. It can be challenging to ferret out what supplements are necessary or beneficial, as well as which ones are reliable and safe. As the number of clients seeking guidance on supplements grows, how does the busy veterinarian evaluate the quality, safety, and efficacy of the myriad of available products?

Choose wisely

Evaluating supplements can be a fatiguing task. In Canada, pet supplements are largely unregulated. This, combined with the seemingly infinite options, dearth of scientific evidence, and ambiguous manufacturing practices, can make decisions difficult for the veterinarian (and even more difficult for the pet owner). So, how can one differentiate ‘snake oil’ from the real deal? There are quite a few questions to consider:

1) Does this product have a Drug Identification Number (DIN)?

Health Canada has developed a category of Veterinary Health Products, which includes supplements such as vitamins, minerals, probiotics, and traditional medicines. Products that obtain a DIN are considered safe, as they have had to show compliance with Natural Health Products Regulations and Good Manufacturing Practices (GMP).

Because a DIN is challenging to obtain, Health Canada has created a new category of Low-Risk Veterinary Health Products (LRVHPs). Supplements can receive a Notification Number (NN) if the manufacturer can show the product is able to provide adequate safety and efficacy data; meets certain ingredient requirements; and adheres to GMP guidelines.

2) Does this product have a NASC seal?

The National Animal Supplement Council (NASC) was developed 20 years ago with the express goal of improving and standardizing manufacturing requirements of pet supplements. The NASC Quality Seal is given only to companies which strictly adhere to the council’s regulations. Companies must follow rigid guidelines for labelling, quality control, and reporting adverse events. Further, they must also submit to an independent facility inspection every two years and random product testing by an independent lab. Products carrying the NASC Quality Seal are considered safe and effective.

3) Source of ingredients, health claims?

Products without a DIN, NN, or NASC Seal require more scrutiny. How are the ingredients sourced? Are they organic? Is the label clear? Does the company make unsubstantiated health claims? Are there any substantiating scientific studies? Are there any ingredients that could be harmful?

What else?

Limiting supplements to a reasonable number (e.g. no more than 10) is recommended for several reasons.

Managing chronic pain is a major quality of life issue for senior pets, as most in this age group have pain and mobility issues from osteoarthritis.
Managing chronic pain is a major quality of life issue for senior pets, as most in this age group have pain and mobility issues from osteoarthritis.

Most herbs are processed through the P450 cytochrome system, meaning an increased number of supplements heightens the risk of potential negative interactions with other supplements and medications. Many products offer similar benefits and there is no proven synergistic effect to using redundant supplements. Herbal products always have the potential to cause individual side effects, such as vomiting, diarrhea, decreased appetite, and lethargy. When using supplements, it is always ideal to introduce one product at a time to better evaluate efficacy and monitor for adverse events.


Finally, always remember the underlying goal is to improve quality of life. The requirement to administer multiple products can greatly detract from the quality of life of both the pet and owner, especially if the pet in question is difficult to medicate.

The decision of which products to stock and recommend can be difficult. Many veterinarians already know the brands they trust from evaluating the available scientific data and from seeing the benefits in their patients. As the list of available senior pet supplements (including claims of efficacy, safety, and drug interactions) is exhaustive and well beyond the scope of this article, what follows are some of the most common supplements used in veterinary medicine. (For those interested in more information, investing in a nutraceutical or natural health handbook is recommended.)

Chronic pain

Managing chronic pain is a major quality of life issue for senior pets. Most seniors have pain and mobility issues from osteoarthritis (OA). Additionally, geriatric cats can also suffer from chronic pancreatitis and inflammatory bowel disease (IBD). Cancer pain is quite common as well, and supplements in this category typically involve agents to improve cartilage health and decrease inflammation.

Essential fatty acids

Multiple studies have elucidated the many benefits of supplementing omega-3 essential fatty acids (EFAs) for a variety of conditions, including:

  • cancer, cardiac, renal, and dermatologic disease;
  • chronic inflammation associated with OA, IBD, and colitis; and
  • cachexia, secondary to cancer or cardiac disease.

Most supplements provide eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the form of salmon, krill, other fish oils, hemp seed, or flax seed. While omega-3 EFAs are commonly added to senior diets, research indicates much higher levels are needed for disease states. One study shows salmon and krill oil are more effective than green-lipped mussels in preventing proteoglycan and collagen degradation in canine arthritis. Fatty acid amides, such as palmitoylethanolamide (PEA), are being investigated for their role in managing chronic pain, dermatologic disease, and cancer.

Pentosan polysulfate sodium

This injectable glycosaminoglycan works to support joint health and reduce OA pain by several mechanisms. It has been shown to decrease cartilage deterioration by reducing cartilage metalloproteinases, which preserves proteoglycan content. It also can suppress anti-inflammatory mediators and stimulate fibroblasts to synthesis hyaluronic acid. Pentosan polysulfate sodium is used in humans to treat interstitial cystitis and has also been used off-label for this purpose in cats (although clinical evidence is lacking).

While considered fairly safe, this product does have heparin-like properties, and is contraindicated for patients with coagulopathies, hemangiosarcoma, or infections. Label recommendations caution against using it concurrently with non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and anti-coagulants due the risk of increasing anti-coagulant actions. Although mostly well tolerated, local injection reactions, along with vomiting, diarrhea, lethargy, and inappetence, have been reported. Nonetheless, multiple canine studies have demonstrated the benefits of this supplement.

Glucosamine and chondroitin sulfate

Both glucosamine and chondroitin are components of cartilage and important to cartilage health. Multiple canine studies suggest glucosamine/chondroitin supplements can, over time, reduce inflammation and pain associated with OA.


Green-lipped mussel (GLM) (Perna canaliculus) appears to be a source of glucosamine and eicosatetraenoic acid (a unique omega-3 EFA). Multiple canine studies have suggested GLM can be helpful in reducing pain, as well as inflammation.


Curcumin is a main component of the spice turmeric (Curcuma longa). Widely touted in humans for its anti-inflammatory and antioxidant effects, clinical studies in dogs suggest similar benefits. Bioavailability, dosing, and overall safety, however, remain concerns.


Methylsulfonylmethane (MSM) is usually added to joint health supplements for its anti-inflammatory and antioxidant properties. While animal studies are limited, MSM appears safe.


S-Adenosylmethionine (SAMe) is the bioactive form of the essential amino acid methionine. Known for its use as an antioxidant in treating liver disease, SAMe has also been used for cognitive dysfunction and OA due to its role in cell membrane maintenance. It can increase serotonin levels, so caution is advised when combing with selective serotonin reuptake inhibitor or tricyclic antidepressants.


Also known as ‘Indian frankincense,’ Boswellia serrata is an herbal supplement derived from tree resin. It has been used for centuries in traditional medicine due to its anti-inflammatory properties.

Additionally, several studies have revealed Boswellia to have selective effects targeting leukotriene synthesis. A 2004 study of dogs with chronic joint and spinal disease treated with a Boswellia supplement showed improvement in 71 per cent of the subjects.

Devil’s claw

Native to South Africa, the devil’s claw plant (Harpagophytum procumbens) has commonly been used in traditional medicine for its anti-inflammatory properties. Further, studies show devil’s claw appears to suppress cyclooxygenase-2.

Cognitive dysfunction

As more pets live into the geriatric stage of the life, cognitive decline has become an increasing concern. Changes in sleep patterns, restlessness, anxiety, and lapses in house training can be stressful for pets, as well as their owners. Photo courtesy kool99 / iStock / Getty Images Plus
As more pets live into the geriatric stage of the life, cognitive decline has become an increasing concern. Changes in sleep patterns, restlessness, anxiety, and lapses in house training can be stressful for pets, as well as their owners.
Photo courtesy kool99 / iStock / Getty Images Plus

As more pets live into the geriatric stage of the life, cognitive decline has become an increasing concern. Changes in sleep patterns, restlessness, anxiety, and lapses in house training can be stressful for pets and their guardians alike.

Supplements able to combat oxidative stress can be helpful to slow deterioration. Many products contain combinations of vitamins C, E, B12, and/or resveratrol with amino acids and essential fatty acids. Natural anxiolytics are also used to help with sleep and anxiety.


The amino acid L-theanine has been shown to be helpful in reducing stress-related behaviours in cats and storm/noise phobias in dogs. As a structural analog of glutamate, L-theanine is able to bind glutamate receptors, thus increasing levels of gamma-aminobutyric acid (GABA). Green tea (Camellia sinensis), which has been used for centuries for health reasons, is a rich source of L-theanine.

Alpha-S1 tryptic casein

Also referred to as ‘alpha-casozepine,’ alpha-S1 tryptic casein is derived from the milk protein casein. It is thought to provide anxiolytic effects due to its structural similarity to the calming neurotransmitter, GABA.


Commonly used in people for sleep disorders, melatonin can safely be used in dogs for nighttime restlessness. Synthesized from tryptophan in the pineal gland, melatonin levels decrease with age. The hormone plays a role in numerous physiologic and endocrine functions and has numerous antioxidant properties as well. Melatonin also appears to have mild anxiolytic effects due to its ability to inhibit dopamine.


Phosphatidylserine has been used in people and companion animals to improve cognitive function. It is a phospholipid naturally occurring in high concentrations at brain and synaptic cell membranes. Two studies examining supplements containing phosphatidylserine (in addition to other ingredients) have shown benefits in treating canine cognitive dysfunction.

Pheromones and aromatherapy

Synthetic pheromones have been shown to have mild anxiolytic properties for dogs and cats. These are species-specific and available in collars and diffusers. Aromatherapy involves using essential oils which must be used carefully as dogs and cats are extremely sensitive. While many oils can be toxic to cats, lavender is safe and has anxiolytic properties. It can be diffused or worn as a collar.


In addition to benefiting gastrointestinal (GI) health, probiotics are being investigated for their role in supporting the immune system and reducing anxiety.

Gingko biloba

This herb, in addition to acting as an antioxidant, appears to act on several neurotransmitters. While evidence is lacking, gingko biloba appears safe and may be beneficial in treating cognitive dysfunction.

Other options

Additionally, chamomile, passionflower, valerian root, St. John’s wort, and lemon balm are all common herbal anxiolytic ingredients. However, while these ingredients have long been used in traditional medicines, scientific evidence supporting use of these products in pets is minimal.

Chamomile does appear to have sedative, anti-inflammatory, and muscle relaxant properties; however, while considered safe for dogs in small doses, chamomile is not recommended for cats due to the risk of causing coagulopathies and GI upset.

Cancer support

Cancer-support supplements mainly include natural antioxidants. Many of these ingredients also appear to slow angiogenesis and tumour proliferation.


An Ayurvedic herb also known as Indian ginseng, ashwagandha has been studied in mice and is found to have anti-cancer properties. Studies suggest it can decrease neurodegeneration, inflammation, adrenal stress, and anxiety.

Green tea extract

In addition to being a source of L-theanine, green tea is rich in catechins (or polyphenols), which are well known for their strong antioxidant properties. It has also been shown to inhibit certain tumour types in lab animals. While green tea contains caffeine, it is considered safe for pets in small doses.

Medicinal mushrooms

Clinical evidence is increasing for the benefits of maitake, shitake, reishi, cordyceps, and turkey tail mushrooms in a variety of diseases due to their anti-cancer, anti-inflammatory, and immune-supporting effects. Mushrooms contain beta-glucans, which can activate complement macrophages and natural-killer cells. It is this mechanism which is thought to reduce tumour proliferation and slow metastasis.

When using supplements, it is always ideal to introduce one product at a time to better evaluate efficacy and monitor for adverse events.
When using supplements, it is always ideal to introduce one product at a time to better evaluate efficacy and monitor for adverse events.

Mushroom supplements can safely be used in patients undergoing radiation and chemotherapy. Generally considered safe and well tolerated, mushroom supplements should be used with caution in patients with diabetes, low blood pressure, liver or kidney disease, and immune mediated disease.

Coenzyme Q10 (Ubiquinone)

A necessary nutrient for mitochondria, coenzyme Q10 (CoQ10) is powerful antioxidant and has been studied for its role in combatting heart disease and cancer. While there is limited research, it appears quite safe and well tolerated.


An iron-binding protein found in colostrum, lactoferrin is being researched as a promising agent in cancer prevention and treatment. It also has antibacterial, antiviral, and antioxidant properties.

Although research involving companion animals is limited, one study found lactoferrin to be effective in reducing tumour cells in an in vitro model of canine mammary cancer.

Milk thistle

Milk thistle has been found to have strong antioxidant and anti-inflammatory properties. Typically used in dogs with liver disease, milk thistle aids with cellular repair and regeneration and detoxification.

TCVM, homeopathy, Bach flower

Traditional Chinese Veterinary Medicine (TCVM) herbal formulas, homeopathics, and Bach flower remedies can be quite effective. While the number of studies looking at efficacy and mechanisms are increasing, the use of these modalities remains controversial. Training in the specific discipline is necessary to utilize these formulas effectively and safely.

Cannabis products

Anecdotal evidence and a growing list of valid research supports the use of cannabis products in pets for a long list of conditions (including chronic pain and inflammation, cancer, anxiety, seizure disorders, and allergic dermatitis).

Pet products abound across Canada, but cannabis is still not legal for pets. Veterinarians can engage in ‘harm-reduction education,’ but cannot legally recommend, prescribe, or dispense these products. However, veterinarians can guide clients on how to use products meant for human consumption obtained at legal dispensaries. These products, however, are typically inconsistent, and it is difficult to obtain third-party testing results. Products marketed specifically for pets are unregulated and considered ‘black market,’ thus requiring thorough investigation.


Supplements for senior pets can be beneficial for many quality-of-life issues; however, they should also be evaluated critically for safety, efficacy, and potential interactions with other supplements and medications. Guiding clients to make wise decisions will not only help improve patient health but augment the client-veterinarian relationship as well.

Katherine Kramer, DVM, DAVBP (canine/feline), Fear Free Certified, is a graduate of the University of Georgia College of Veterinary Medicine and a Diplomate of the American Board of Veterinary Practitioners in Canine and Feline Practice. She is a member of the Canadian Association of Veterinary Medicine, College of Veterinarians of British Columbia, International Veterinary Acupuncture Society, American Association of Feline Practitioners, and the International Veterinary Academy of Pain Management. In addition to her position as medical director of the VCA-Canada Vancouver Animal Wellness Hospital, Dr. Kramer currently serves as a director of the Canadian Association of Veterinary Cannabinoid Medicine.


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