Nutritional management of canine brain aging - DVM
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Nutritional management of canine brain aging
With pets living longer comes increased prevalence of age-related behavioral and cognitive problems; diets rich in antioxidants, mitochondrial cofactors benefit

DVM InFocus

Use of these testing procedures has shown that aged dogs are on average, able to learn simple associative tasks such as visual discrimination (learning that one of two different objects covers a food reward), at the same level as younger dogs. Significant impairment is seen, however, on more complex discrimination learning problems, such as when the objects become increasingly similar or in reversal tasks, where the pet first learns under which object the food is located and then must learn that the reward has been moved to the previously unrewarded object.

  • Memory

In addition to learning ability, memory is also compromised in aged dogs.

Aged dogs seem to fall into one of three categories based on learning and memory testing: (1) unimpaired or successful agers; (2) age-impaired; (3) severely impaired. These clusters of aged dogs may be analagous to declines along a "cognitive continuum" in people with mild age-associated memory impairment followed by cognitive decline and dementia.

The decline in learning and memory documented in laboratory studies to arise as early as 6 to 7 years of age is consistent with behavioral changes observed in dogs with CDS.

Table 1: Behaviors evaluated in dogs to assess age-related cognitive decline*
Careful questioning of the owner is the best way for veterinarians to detect early signs of cognitive impairment, since many of the early signs are subtle and might otherwise not be reported. A questionnaire is a useful diagnostic tool and an excellent means of tracking changes and response to therapy (Table 1).

  • Can food retard decline?

A series of studies were initiated to test the hypothesis that a food enriched with complex mixtures of antioxidants and mitochondrial cofactors could result in improvements in learning and memory and reduce the extent of pathology that accumulates in aged canine brains.

A longitudinal investigation of the effects of dietary management on cognitive function of Beagles has recently been completed. The experimental subjects are groups of aged Beagle dogs (10 to 13 years old) and young dogs (3 to 5 years old). The study was conducted as a randomized controlled clinical trial with each animal assigned to an extruded senior dog food (control) or an enriched food. No differences in cognitive ability existed between groups prior to dietary intervention

The enriched food was supplemented with Vitamins E and C, a mixture of fruits and vegetables rich in carotenoids and flavonoids and mitochondrial cofactors (L-carnitine, dl-α-lipoic acid). Vitamin E is a lipid-soluble vitamin that protects cell membranes from oxidative damage, while vitamin C is a water-soluble vitamin that helps replenish vitamin E cellular levels. L-carnitine is a precursor to acetyl-L-carnitine, which is involved in mitochondrial lipid metabolism and maintaining efficient mitochondrial function.

Lipoic acid is an antioxidant nutrient capable of redox recycling of other antioxidants and raising intracellular glutathione levels. Glutathione is the major intracellular water-soluble antioxidant.

In one example from the study, dogs were fed the control or enriched food for six months and tested on four oddity discrimination learning tasks that became increasingly difficult. Aged dogs made significantly more errors than young dogs in all tasks. This would seem to support the adage that "you can't teach old dogs new tricks."

However, old dogs receiving the enriched food performed better on all tasks than old dogs eating the control food. The enriched food produced the most significant improvement in the ability of old dogs to learn complex tasks.

  • Environmental enrichment

Another component of this study was to determine the effect of environmental enrichment on learning ability in old dogs.

Half of the control diet dogs and half of the enriched diet dogs were given an enriched lifestyle with an increase in daily walks, new toys and a regular cognitive testing.

At the end of two years, the dogs with the combination of enriched environment and enriched food scored statistically better in the learning tasks than those dogs given an enriched environment or enriched food alone.

  • Reduction in age-related behavior changes?

In addition to the extensive laboratory testing reported above, a randomized, double-blind, controlled clinical trial was conducted to evaluate effects of dietary enrichment in dogs with age-related behavioral changes.


Source: DVM InFocus,
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