Last month, we investigated the contributions and causes of cognitive dysfunction (CD) in dogs as they age. One factor we
looked at was oxidative damage, which can cause inflammation or damage to the neurons. Increased oxidative stress appears
to affect all major classes of molecules involved in neurotransmission. Development of oxidative stress may not be independent
of energy source or use, and molecular effects may not be independent of energy intake and use. For example, intermittent
fasting has been reported to induce the production of brain-derived neurotrophic factor (BDNF) — a key neurotrophic factor
associated with neurogenesis and molecular learning and memory, particularly in the hippocampus.
Although we are truly in our infancy in terms of understanding these complex inter-relationships, the future looks brighter.
Since obesity is an epidemic in pets, we are unlikely to encourage our clients to engage in intermittent fasting for their
pets. Despite this, there are dietary strategies available for addressing oxidative stress. Other forms of intervention for
preventing or treating cognitive decline include supplements, medications, and cognitive and physical stimulation.
New foods are being developed all the time, but two should catch our attention. Prescription Diet b/d Canine (Hill's Pet Nutrition)
is formulated to redress oxidative stress. It does so by providing high levels of antioxidants, including vitamins C and E
and L-carnitine, to facilitate energy availability and enhance neuronal signal transmission. The diet combined with environmental
stimulation demonstrated the strongest effect in laboratory dogs. Effects of such an antioxidant diet are also apparent in
levels of BDNF, which have been shown to be similar to those found in young dogs.
Purina Veterinary Diets EN Canine Formula (Nestlé Purina) is designed to use medium-chain triglycerides (MCTs) as an energy
source and is accordingly high in omega-3 and omega-6 fatty acids, which may help maintain neuronal integrity. Both of these
diets take advantage of antioxidants in the hopes of decreasing the effects of oxidative stress.
Senilife (Ceva Santé Animale) uses antioxidants (resveratrol), structural enhancers of neuronal membranes (phosphatidylserine)
and a coenzyme of neurotransmitter function (pyridoxine) to address the three factors that can affect brain aging. Aktivait
(Vet Plus, U.K.; available only online in the United States) also addresses structural concerns by providing docosahexaenoic
acid (DHA), eicosapentaenoic acid (EPA) and phosphatidylserine, plus the antioxidants vitamins C and E, selenium, N-acetyl
cysteine and alpha-lipoic acid.