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Canadian Vet is unique in that it keeps Canadian veterinarians informed about the latest companion animal, livestock, equine, avian, exotic and other animal species health issues. Each issue also includes useful practice management articles. Canadian Vet is written by our own team of expert medical writers, and is reviewed for accuracy.

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The golden years: new tricks for feeding old dogs

HALIFAX, NS – More dogs are living longer; senior dogs now account for about one-third of the pet dog population. As there is no established AAFCO nutrient profile for a "senior" life stage, dog owners are left with hundreds of pet foods to choose from. Advice and information regarding thebest” food is widely available, from trainers to pet food retailers, magazines, the Internet, and social media. Julie A. Churchill, DVM, PhD, DACVN, presenting at the Atlantic Provinces Veterinary Conference, said this is why it is so critical for the veterinary health care team to play an active role in providing credible nutritional advice, especially for senior dogs that have unique nutritional concerns.

How old is old?

Dog life expectancies vary widely depending on breed and body size. Changes related to aging are variable and may include loss of hearing or vision, reduced energy requirements and lean body mass, and a decline in various organ functions. According to the American Animal Hospital Association Senior Care Guidelines, with exception of large-breed dogs, most reach middle age by 7-8 years of age and should be considered seniors when they reach the last 25% of the predicted life span for their breed. Physiologic changes that occur in middle-aged and senior dogs make them less tolerant of nutritional deficiencies or excesses. Therefore, explained Dr. Churchill, a vital component of preventive medical care should include a health risk assessment for early detection of health problems, and measures to prevent or slow the onset of age-related diseases. She said that every senior health screen should include a thorough nutritional assessment followed by an individualized nutritional recommendation.

Performing a nutritional assessment

Understanding the nutritional changes that occur with aging, and identifying any changes in the individual patient, can help the clinician better match the appropriate food with their unique needs. Health and nutritional status are a dynamic process requiring ongoing re-evaluation and modifications.

Patient assessment
An initial patient assessment can be done quickly based on the patient’s complete medical and diet history, thorough physical examination, and appropriate lab work. The nutritional screening process (Table 1) can quickly identify patients with nutritional risks. Nutritional recommendations should include the specific name of food that matches the pet’s current nutritional needs, the amount and frequency for feeding, and a monitoring plan.

If risk factors or age-related problems are identified, an extended evaluation and management plan is indicated. This should address common age-related diseases that may be influenced by nutritional management (Table 2), including obesity, osteoarthritis, and cognitive dysfunction.

Table 1. Initial screen: assessing for nutritional risk factors


Nutritional Screen for Risk Factors

Require extended evaluation if  (✓)

HISTORY OF:

Treats/snacks/human foods >10% intake

Inadequate information/inappropriate feeding/food

Consuming unconventional diets

Previous/ongoing medical problems

Gastrointestinal signs

PHYSICAL EXAMINATION:

Any abnormal body condition score (≠5/9 or 3/5)

Any muscle condition score <3

Unintentional weight loss OR gain

New medical condition

Poor skin hair coat

Dental disease

Adapted from Table 2, AAHA Nutrition Assessment Guidelines

Table 2. Extended screening: assessing senior dogs for nutritionally relevant age-related factors

Abnormal body condition: Is this pet overweight or underweight?

Diet: Is the pet eating appropriate amounts of balanced diet?

  • Assess appetite and intake
  • Assess ability to eat; prehension, mastication, swallowing for those underweight &/or poor intake
  • Assess sensory input; smell, vision, palatability of food. Consider palatability enhancer if necessary

Mobility and access to food and water

  • Is the pet able to walk, access food provided? Able to stand to eat?
  • Other pets or physical limitations impairing access?

Mobility and exercise: is the pet’s MCS normal (3/3)?

  • Presence of osteoarthritis, lameness, pain? Play a role in maintenance of comfort, fitness and healthy BCS
  • Activity minimizes sarcopenia
  • Exercise and activity provide mental stimulation and environmental enrichment

Assess cognitive function

  • Disorientation/confusion-becomes lost or confused, fails to recognize familiar people?
  • Changed interactions with family members? Isolates or seeks attention less often?
  • Change in sleep/activity cycles? Wander or pace, sleep more in day, less at night?
  • Loss of house training (non-medical reasons)

Diet assessment
A complete diet history is important for evaluating the pet’s current nutritional status. This should identify all snacks, treats, and nutritional supplements by type and amount.  The drug/supplement history should include questions about the use of food to administer medication, as it may comprise a significant portion of the dog’s intake.  Diet history, combined with the patient assessment, provides information about the patient’s daily caloric requirements and specific nutrient intake. Dr. Churchill stressed that care should be taken when reducing the amount of a high calorie product as a way to limit calorie intake, as it could lead to deficiencies of other essential nutrients and increase hunger or undesirable food-seeking behaviours.

Feeding management assessment
Determine whether other pets present competition or limit food access, whether food is accurately measured, how much/often food is offered, and how much is eaten. Ask if there have been recent changes to the feeding plan and why, as well how the pet accepted those changes. This will allow the veterinary team to determine the nutritional adequacy of the current diet, and to identify factors that could contribute to potential success or problems with adherence to a new recommendation.

Nutritional intervention of selected age-related diseases

Nutritional assessment of older pets is an ongoing process. Dogs may experience a variable and wide variety of metabolic changes as they age, so it is critical for the healthcare team to partner with clients to help ensure success and maintain adherence to the feeding and monitoring goals.

Overweight/obesity  
It is important to monitor the pet’s diet, body weight, body condition score, and muscle condition score at each visit, and to revise a diet and exercise plan whenever undesired changes occur. Creating a negative energy balance promotes weight loss; this is best achieved by feeding foods with low calorie density, increased protein content, and an increased nutrient calorie ratio.

Degenerative joint disease
Osteoarthritis (OA) affects as many as 20% of dogs by adulthood, and unhealthy weight gain is recognized as a primary risk factor development and progression of OA. Nutritional strategies for OA include weight and muscle management, and providing long-chain omega-3 fatty acids. Loss of excess body weight/fat can improve clinical signs of lameness in arthritic dogs, and be can achieved by selecting a complete and balanced diet with the appropriate caloric requirements.

Long chain omega-3 fatty acids (n-3) show the greatest evidence for synovial anti-inflammatory effects compared to other nutraceuticals. Marine oils (EPA> DHA) are preferred with more effective anti-inflammatory effects compared to shorter chain flax or other plant sources of n-3 oils. To date, there is no standard accepted dose, but Dr. Churchill said that she uses 310 mg/(kg)3,4 or ~ 1745 mg (EPA+ DHA) per 10 kg BW  for canine OA.

Cognitive dysfunction
As many as 20-68% of middle age to elderly dogs experience cognitive dysfunction or behavioural changes, which can manifest in varying degrees of mental decline1 (Table 2). Nutraceuticals may have potential use both in prevention and treatment, but are most effective when combined with exercise and environmental enrichment.2-4

Antioxidants
Multiple studies have shown improved clinical signs of age-related cognitive changes in dogs fed antioxidant-enriched diets or supplements.2-4

Medium chain triglycerides (MCT)
Studies5-6 have shown that supplementation with MCT improved cognitive performance and preserved brain structure of older dogs. MCT provides an alternate cerebral energy source by way of ketones without restricting dietary carbohydrate or proteins.

Supplements versus enriched diets
It is important to note that nutraceutical supplements have not been adequately assessed for efficacy, optimal doses, or nutrient interactions. Therefore, Dr. Churchill stressed that the base diet must meet the macronutrient needs of the patient, and provide an adequate dose of the intended supplement. If not, consider selecting a more appropriate diet and add the appropriate dose of supplement.

References
1. Zakona G, Garcia-Belenguer S, Chacon G, et al. Prevalence and risk factors for behavioural changes associated with age-related cognitive impairment in geriatric dogs. J Sm Anim Pract 2009;50:87-91.
2. Fahnestock M, Marchese M, Head E, et al. BDNF increases with behavioral enrichment and an antioxidant diet in aged dog. Neurobiol Aging 2012;33(3):546-554.
3. Pop V, Head E, Hill MA, et al. Synergistic effects of long-term antioxidant diet and behavioral enrichment on beta-amyloid load and non-amyloidogenic processing in aged canines. J Neurosci 2010;30:9831-9839.
4. Roudebush P, Zicker SC, Cotman CW, et al. Nutritional management of brain aging in dogs. JAVMA 2005;227:722-728.
5. Taha AY, Henderson ST, Burnham WM. Dietary enrichment with medium chain triglycerides (AC-1203) elevates polyunsaturated fatty acids in the parietal cortex of aged dogs: implications for treating age-related cognitive decline. Neurochem Res 2009;34:1619-1625.
6. Pan Y, Larson B, Araujo JA, et al. Dietary supplementation with medium-chain TAG has long-lasting cognition-enhancing effects in aged dogs. Br J Nutr 2010;103:1746-1754. CV