By Chloe Poolman

The importance of nutrition for senior dog health

By Chloe Poolman, Pet Nutritionist, Premier Nutrition

Correct feeding of senior dogs is vital for healthy ageing, and in helping to control age related changes that might impact on the dogs’ quality of life. as this may help to maintain lean body mass. Dietary supplementation of L-carnitine improves nitrogen retention, increasing lean mass and reducing fat mass (MacIntosh, 2001). Carnitine is biosynthesized in the liver and kidneys from the amino acids’ methionine and lysine in the presence of ascorbate. Although dogs can complete this pathway without additional supplementation, the level at which this synthesis can be maintained declines in older dogs.

There is no defined chronological age as to when a dog progresses from being adult to senior, but pet parents tend to notice differences in their dogs’ health, activity level and weight as their pets age. The chronological age at which a dog enters its senior period will depend on breed and breed size and will also vary in individual pets. For example, a higher lifespan is expected in smaller breed dogs compared with larger breed and, in particular, giant breed dogs. Commonly, large breed dogs might be classified as senior from the age of 5-8 years old and small breeds from about 10 years of age (Michell, 1999).

Owners associate their pet’s well-being with behaviours learnt in their adult life, by their activity level on walks and their subsequent comfort whilst participating in these activities. Reduced mobility is one factor which is often noticed by pet owners as dogs age, but other common pathologies associated with age are renal diseases, obesity, dental issues, and cognitive impairments.

Weight and energy allowance

Senior dogs are at a greater risk of becoming overweight and obese so energy supply should be adjusted to maintain optimal body condition, especially where activity levels might become reduced as the pet ages. Maintaining an optimal body condition appears to be a key factor in healthy ageing in dogs and lifetime restrictive energy allowances increases median lifespan and delays the onset of chronic disease (Lawler et al., 2008) and osteoarthritis in dogs (Kealy et al., 1997, Lawler et al., 2008). Lower calorie density foods are one tool to aid owners to provide appropriate energy supply to senior dogs. However, it is important to provide sufficient high-quality protein to senior dogs

Osteoarthritis is one of the most commonly diagnosed joint diseases in ageing dogs and is recognised as the progressive degeneration and remodelling of synovial joints as the cartilage becomes damaged and triggers an inflammatory response which can cause great discomfort. Anderson et al., (2018) estimated 11.4% of dogs over 8 years old were affected by osteoarthritis. Although osteoarthritis has a known genetic influence, the disease can be exacerbated by the dog’s activity levels, diet and their breed, with larger breeds commonly experiencing

Joint health

One area that is important to enable senior dogs to live a comfortable, active life is joint health. The first and second most abundant minerals in the dogs’ body are calcium and phosphorus, respectively. These are involved in both the structural formation of bones and teeth, as well as functional roles within blood coagulation and nerve impulse transmission (Stockman et al., 2021). Vitamin D is an essential nutrient involved in the homeostasis of calcium and phosphorus. If the requirements of these nutrients are not adequately met in early life, skeletal abnormalities may form which can severely impact the quality of life within the senior years and increase the inflammatory response caused by poor orthopaedic health. Adequate Ca:P ratios should be maintained in senior dogs.

osteoarthritis at some stage. Glucosamine & chondroitin are ingredients commonly included in complete and complementary pet foods designed for joint health support for senior dogs. Glucosamine regulates the synthesis of collagen in cartilage, whereas chondroitin inhibits the destructive enzyme pathway which breaks down the cartilage and joint fluid (Bhathal et al., 2017). Alongside this, both ingredients contribute towards the creation of glycosaminoglycans and proteoglycans, which are recognised for being building blocks for cartilage formation (Beale, 2004). Also supporting the body’s natural anti-inflammatory response is the organic sulphur compound Methylsulphonylmethane (MSM) (Brien et al., 2008).

Supplementation of pet foods with omega-3 fatty acids for a period of 6 months significantly improved the ability of geriatric dogs to rise from a resting position, and improved comfort whilst walking (Roush, 2010). Omega-3 fatty acids have been shown to support the antiinflammatory response through increasing eicosanoids and reducing the activities of proteoglycan-degrading enzymes. Omega-3 fatty acids are commonly found in ingredients such as marine algae and fish oils. Furthermore, supplementing omega-3 fatty acids to senior dogs can also help support the immune system and positively modulate the gut microbiome when challenged (Fritsch et al., 2010).

Digestive health and fibre

Over time, senior dogs gut microbiota shows a gradual reduction in beneficial bacteria and an increase of facultative anaerobes which can generate an inflammatory response and increase oxidative stress (Pilla and Suchodolski, 2019). Changes in gastrointestinal function can result in inconsistent stool quality, longer colonic transit time and inefficient absorption of nutrients. The inclusion of fermentable fibre within the diet can significantly reduce the risk of enteric infection and improve nutrient absorption to overall improve quality of gut health and stools (Ephraim et al., 2020). Prebiotics such as fructooligosaccharides (FOS) and mannanoligosaccharides (MOS) promote the growth of the ‘good bacteria’, Lactobacillus and Bifidobacterium (Swanson et al., 2002). Diets for senior dogs should also contain sufficient fibre to ensure adequate intestinal motility, typically this is included in pet foods with ingredients such as sugar beet pulp.

Cognitive health

Senior dogs may experience age related cognitive decline as a result of oxidative damage caused by free radicals which can lead to dysfunction of neural cells (Head et al., 2007). Dietary antioxidants like vitamins E and C, and selenium may be important in helping to maintain antioxidative defence in older dogs. Cognitive dysfunction syndrome (CDS) results from irreversible degeneration of the brain beyond normal aging, including changes in brain glucose metabolism and is more severe than age related cognitive decline. Salvin et al., (2010) estimated that 14.2% of dogs 8 years and older are affected by CDS. Prevalence of CDS increases with age but remains underdiagnosed by veterinarians. Dietary supplementation with mediumchain TAG (MCT) has been shown to improve cognitive function in aged dogs (Pan et al., 2010; Pan et al., 2017). There is consideration for the inclusion of omega-3 fatty acids to support cognitive health in ageing dogs.

Immune function

Senior dogs may develop age related immunocompetence (Hall et al., 2006). Zinc intake can be adjusted to higher levels within the recommended framework given its essentiality for many biological systems including immune function.

Prebiotics (FOS and MOS) have beneficial effects on the immune status of dogs by increasing IgA and lymphocyte concentrations (Swanson et al., 2002). High concentrations of dietary beta-carotene have been shown to heighten cell-mediated and humoral immune responses in dogs (Chew et al., 2000). Furthermore, carotenoids such as beta-carotene, lutein and zeaxanthin found in ingredients such as marigold meal are linked to maintaining healthy vision (Paiva and Russell, 1999).

As dogs age, their quality of life and daily activity is influenced by a range of conditions to differing extents depending on the size and breed of the dog. The healthy ageing of all senior dogs can be supported by the addition of functional ingredients, antioxidants, and correct nutritional management.

References available on request from: Chloe Poolman - Pet Nutritionist Email: chloe.poolman@premiernutrition.co.uk Tel: 07892780264 Chloe Joined Premier Nutrition in 2019 as a Support Nutritionist after graduating Harper Adams University with a BSc (Hons) in Bioveterinary Science. Previous to this, Chloe completed a placement with a leading feed additive business. Chloe Joined the Pet Team in 2021 to provide technical and nutritional support alongside legislation and labelling advice. Chloe is FAR registered and also a Registered Animal Medicine Advisor – category R.