Pug

        With improved nutritional status, advances in medical technology, and the implementation of spaying/neutering, the lifespan of dogs has greatly extended compared to 30 years ago. Nowadays, dogs over 20 years old have become quite common.

        Many people focus most of their energy on playing with their dogs and grooming them, but seldom pay attention to the issue of aging.

        What is aging? There are many definitions of aging, but it can all be summarized as the cumulative effect of different damages leading to an increased probability of death! “Damage” can be broadly divided into two categories: aging caused by genes, or damage to DNA caused by environmental factors and free radical interactions.

        Lifestyle plays a key role in the aging process. Obesity, malnutrition, trauma, various stresses (such as multiple pregnancies, overcrowding, and extreme climates), or overwork will shorten lifespan.

        What are the manifestations of aging?

        Physiologically, pigment deposition (such as around the mouth and nose), thickened skin, coarse coat, muscle atrophy, lack of vitality and strength, reduced bone density, decreased physiological tolerance, decline in vision or hearing, increased risk of dehydration (reduced fluid absorption), impaired temperature regulation (sensitivity to cold), stiffness, and reduced immune system function (more susceptible to infections).

        Mentally, reduced adaptability (easily startled), decreased response to stimuli, poor appetite (reduced perception of smell and taste), anorexia, loss of learned behavior, indifference to external environments, decreased activity, and disorientation.

        The impact of aging on body size

        For large dogs (generally fully mature at 18 to 24 months), signs of aging appear from 7 years old. On the other hand, small dogs also begin aging after 15 years old. Changes in appearance and body size of various breeds can reflect the impact of aging on different systems. Small dogs tend to develop mitral valve disease (a type of heart disease) and dental problems, while large dogs are more prone to degenerative joint disease.

        Aging leads to a decline in immune system function

        Many studies emphasize the impact of aging on immune system activity. Immune defense functions decline in activity, efficiency, and scope, a phenomenon known as immunosenescence. This change in senior dogs is very similar to that in elderly humans. Broadly speaking, lymphocytes (B cells and T cells) decrease. However, innate immune function seems unaffected by age (the activity of neutrophils and NK cells in older dogs appears unchanged), and exposure to new antigens or vaccination does not show obvious impairment in serologic response. Thus, despite many mechanisms still not fully understood, infectious and neoplastic diseases are more common in elderly dogs. We also know that regardless of the extent of damage, recovery during old age is slower (from pruritus to surgical sutures). The endocrine system also changes with age (excluding iatrogenic hyperadrenocorticism): thyroid function in dogs tends to decline. Diabetes results from years of overnutrition. With aging, kidney function gradually declines and can eventually lead to renal failure. Free radicals have been clearly implicated in many diseases such as diabetes, osteoarthritis, cancer, heart failure, and neurodegenerative diseases.

        The role of nutrition

        Mammals’ digestion and absorption of nutrients decline with age. This can occur even in healthy individuals but may go unnoticed, especially without other obvious clinical symptoms. It is thought this decline may be due to changes in bile composition, decreased secretion and activity of digestive enzymes, atrophy of intestinal epithelial cells, and altered gastric emptying and digestive transit times. More effective diets should be introduced early because over time animals’ sense of smell and taste deteriorate and appetite decreases. It is recommended to gradually introduce new diets, choosing foods that are palatable and nutritionally balanced. Older animals do not get thirsty as easily as younger ones but are often chronically dehydrated. This means any disruption of water/electrolyte balance (such as diuretics used in treating heart disease) can cause severe clinical dehydration. Most senior dogs have cardiovascular and renal systems that are overworked and have reduced adaptability. Fluid therapy is an important treatment for all sick elderly dogs. Because older animals are more prone to obesity, degenerative joint disease, kidney disease, dental disease, and metabolic and endocrine disorders, their diets should be adjusted to minimize organ failure risks. Fat, phosphorus, and fiber levels should be adapted to meet the needs of aging animals while ensuring protein quality and digestibility (remember that protein is essential, even for aged animals!). Suitable for older dogs’ needs. Additionally, special nutrients such as antioxidants and essential fatty acids have been shown to effectively control geriatric diseases. Diet considerations should include texture and frequency of daily meals. Small frequent meals are advised.

Aging of Dogs