Brennen McKenzie, MA, MSc, VMD

Disclaimer: Loyal has no affiliation or relationship with Purina. We’re writing about two foundational studies their scientists published in 2002 and 2008 that have informed important research in the longevity field.

One of the first logical questions for a good skeptic to ask when thinking about canine aging biology is whether it is plausible that we can extend lifespan (years lived) and healthspan (healthy years lived) in dogs. Is there reliable evidence that aging is not something immutable and inevitable but something we can actively alter? If so, how strong is that evidence, what does it suggest we should try, and what do we still need to learn?

Longevity research decades old — from worms to mice to dogs

The good news is that there are decades worth of research showing that lifespan can be extended and age-associated disease reduced in a variety of species. Much of this research has involved lab animals, such as roundworms, fruit flies, and mice1-3. Such studies are useful for understanding basic principles in biology, and they suggest hypotheses to test in other species, but they aren’t sufficient to prove a given treatment or preventative intervention will work in other species (such as dogs). There are even some laboratory studies in dogs that strengthen the basic understanding of aging and how we might influence it, but again this only gets us so far. 

Fortunately, we have more than this. While we can’t predict whether specific drugs or many other treatments will work until we’ve done the science to test them, we know that healthspan and lifespan can be extended in dogs because it’s been done! The one method that has been shown effective in many different animals, including dogs, is caloric restriction.

Caloric restriction can increase your dog’s lifespan

Caloric restriction is defined as a substantial reduction in calorie and nutrient intake without malnutrition. The specific details vary among studies, but in general the key appears to be reducing total calorie intake significantly (perhaps 20-40%) without inducing micronutrient (vitamin and mineral) deficiencies. There are some other strategies that have proven effective or appear promising — for example, changes in protein intake or intermittent fasting — but 

The good news is that there is strong evidence for the benefits of caloric restriction in dogs. 

 in Labrador retrievers paired littermates by sex and weight and then randomly assigned one to unrestricted feeding and the other to a calorie intake 25% less than its paired littermate4,5. In order to avoid obesity in the control dogs, at about 3 years of age the protocol was changed so these dogs were fed to maintain an optimal body condition rather than 

 (as often as they wanted), but the calorie restricted dogs were still fed 25% less than their paired littermates ate. The study ran for the entire lives of these dogs.

_________________________________________

The calorie restricted dogs had a median lifespan of 13 years, 1.8 years (16%) longer than the 11.2 years in the control group.

The calorie restricted dogs had a median lifespan of 13 years, 1.8 years (16%) longer than the 11.2 years in the control group. Calorie restricted dogs also developed arthritis 1.5 years later on average than the control dogs. Some dogs developed cancer in both groups, but the average age of death from this cause was 2 years later in the restricted calorie group (11.6 years vs 9.7 years)4,5.

A representation of Fig. 1. Survival curves for calorie restricted (green 一) and control (ー・ー) feeding groups from Kealy 

Caloric restriction can positively impact your dog’s metabolic health

This study also showed that increasing insulin resistance independently predicted shorter lifespans and more chronic disease. Insulin resistance and chronically elevated blood insulin levels have been identified in other species as a feature of aging-related metabolic dysfunction, and these data suggests that is also true in dogs.

There are several laboratory measures of glucose metabolism and insulin activity in dogs, including insulin sensitivity, insulin AUC (area under the curve — or how much insulin is needed to process glucose in the body), glucose AUC (or how fast glucose appears and how much time is needed for the body to uptake and use up the glucose), and peak insulin.

All of these measures showed impaired glucose metabolism and insulin response in the control dogs compared to those dogs who were calorie restricted.5 (In other words, all these values were significantly worse in the non-calorie restricted dogs.) This suggests that some of the benefits of calorie restriction may stem from preservation of healthy glucose metabolism and insulin response, and that other therapies that achieve this may have similar positive effects.

Taken together, data from this study shows that a decrease in metabolic health is tied to increased morbidity (or the occurrence of disease). This suggests that maintaining insulin sensitivity through dietary management or other interventions could be crucial for extending healthspan and lifespan in dogs.

Values related to metabolic health – insulin and glucose response to intravenous glucose challenge of 9-12 year old control-fed (CF) and calorie restricted (DR) Labrador retriever dogs from Table 3. Lawler 

Caloric restriction can be difficult to sustain long-term

Dramatic, lifelong caloric restriction is not a practical method of extending lifespan and healthspan in dogs. Without appropriate diet formulation and close monitoring, it is easy to cause malnutrition, which can undermine the potential benefits and even be directly harmful. Feeding is also an important element in the human-animal bond, and asking owners to drastically restrict their dogs’ caloric intake for life can interfere with this bond and the success of the human-dog relationship.

obesity is a tremendous and growing problem

 in companion dogs. It’s hard enough to feed our dogs appropriately to maintain a healthy weight, so choosing to severely restrict their food intake even to obtain significant lifespan and health benefits seems unlikely to be possible for most of us. 

Alternatives to caloric restriction — what Loyal is working towards

Fortunately, there may be alternatives to caloric restriction for improving the lifespan and healthspan of dogs. Studies of caloric restriction have taught us a lot about the fundamental biology of aging, and there are many potential means to achieve some of the benefits of caloric restriction other than feeding dramatically less food to our dogs. Promising avenues of future research may include diets with different composition, the timing of feeding, and medicines that mimic aspects of the physiologic response (and positive effects) of caloric restriction. 

While no clearly effective longevity therapy is yet available, science has already proven that aging can be influenced. There are many different ongoing research efforts aiming to translate the decades of knowledge concerning aging biology into more, healthier years for our dogs — including what we’re working on at Loyal! Science will ultimately tell us which, if any, will work and what the relative risks and benefits will be, as is always the case, but having a plausible hypothesis and established potential mechanisms is a good first step.

Can science actually make your dog live longer? The Purina study

Disclaimer: Loyal has no affiliation or relationship with Purina. We’re writing about two foundational studies their scientists published in 2002 and 2008 that have informed important research in the longevity field.



One of the first logical questions for a good skeptic to ask when thinking about canine aging biology is whether it is plausible that we can extend lifespan (years lived) and healthspan (healthy years lived) in dogs. Is there reliable evidence that aging is not something immutable and inevitable but something we can actively alter? If so, how strong is that evidence, what does it suggest we should try, and what do we still need to learn?







<h2 class="wp-block-heading">Longevity research decades old — from worms to mice to dogs</h2>



The good news is that there are decades worth of research showing that lifespan can be extended and age-associated disease reduced in a variety of species. Much of this research has involved lab animals, such as roundworms, fruit flies, and mice1-3. Such studies are useful for understanding basic principles in biology, and they suggest hypotheses to test in other species, but they aren’t sufficient to prove a given treatment or preventative intervention will work in other species (such as dogs). There are even some laboratory studies in dogs that strengthen the basic understanding of aging and how we might influence it, but again this only gets us so far.&nbsp;



Fortunately, we have more than this. While we can’t predict whether specific drugs or many other treatments will work until we’ve done the science to test them, we know that healthspan and lifespan can be extended in dogs because it’s been done! The one method that has been shown effective in many different animals, including dogs, is caloric restriction.







<h2 class="wp-block-heading">Caloric restriction can increase your dog’s lifespan</h2>



Caloric restriction is defined as a substantial reduction in calorie and nutrient intake without malnutrition. The specific details vary among studies, but in general the key appears to be reducing total calorie intake significantly (perhaps 20-40%) without inducing micronutrient (vitamin and mineral) deficiencies. There are some other strategies that have proven effective or appear promising — for example, changes in protein intake or intermittent fasting — but <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230387/">overall the best evidence</a> is for total calorie reduction.



The good news is that there is strong evidence for the benefits of caloric restriction in dogs. <a href="https://pubmed.ncbi.nlm.nih.gov/18062831/">One long-term study</a> in Labrador retrievers paired littermates by sex and weight and then randomly assigned one to unrestricted feeding and the other to a calorie intake 25% less than its paired littermate4,5. In order to avoid obesity in the control dogs, at about 3 years of age the protocol was changed so these dogs were fed to maintain an optimal body condition rather than ad libitum (as often as they wanted), but the calorie restricted dogs were still fed 25% less than their paired littermates ate. The study ran for the entire lives of these dogs.



_________________________________________



<h2 class="wp-block-heading has-text-align-center has-regular-font-size">The calorie restricted dogs had a median lifespan of 13 years, 1.8 years (16%) longer than the 11.2 years in the control group. </h2>



_________________________________________



The calorie restricted dogs had a median lifespan of 13 years, 1.8 years (16%) longer than the 11.2 years in the control group. Calorie restricted dogs also developed arthritis 1.5 years later on average than the control dogs. Some dogs developed cancer in both groups, but the average age of death from this cause was 2 years later in the restricted calorie group (11.6 years vs 9.7 years)4,5.







<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="576" src="https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1-1024x576.png" alt="" class="wp-image-1213" style="width:1024px;height:auto" srcset="https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1-1024x576.png 1024w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1-300x169.png 300w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1-768x432.png 768w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1-1536x864.png 1536w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1-2048x1152.png 2048w" sizes="(max-width: 1024px) 100vw, 1024px" /><figcaption class="wp-element-caption">A representation of Fig. 1. Survival curves for calorie restricted (green 一) and control (ー・ー) feeding groups from Kealy et al., J Am Vet Med Assoc 220, 1315-1320, 2002.</figcaption></figure>







<h2 class="wp-block-heading">Caloric restriction can positively impact your dog’s metabolic health</h2>



This study also showed that increasing insulin resistance independently predicted shorter lifespans and more chronic disease. Insulin resistance and chronically elevated blood insulin levels have been identified in other species as a feature of aging-related metabolic dysfunction, and these data suggests that is also true in dogs. There are several laboratory measures of glucose metabolism and insulin activity in dogs, including insulin sensitivity, insulin AUC (area under the curve — or how much insulin is needed to process glucose in the body), glucose AUC (or how fast glucose appears and how much time is needed for the body to uptake and use up the glucose), and peak insulin.



All of these measures showed impaired glucose metabolism and insulin response in the control dogs compared to those dogs who were calorie restricted.5 (In other words, all these values were significantly worse in the non-calorie restricted dogs.) This suggests that some of the benefits of calorie restriction may stem from preservation of healthy glucose metabolism and insulin response, and that other therapies that achieve this may have similar positive effects.



Taken together, data from this study shows that a decrease in metabolic health is tied to increased morbidity (or the occurrence of disease). This suggests that maintaining insulin sensitivity through dietary management or other interventions could be crucial for extending healthspan and lifespan in dogs.



<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="576" src="https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1024x576.png" alt="Values related to metabolic health — adapted from Lawler et al. 2008
Compares insulin and glucose and insulin sensitivity values of control-fed (CF) and diet-restricted (DR) groups" class="wp-image-1207" srcset="https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1024x576.png 1024w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-300x169.png 300w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-768x432.png 768w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-1536x864.png 1536w, https://blog-admin.loyalfordogs.com/wp-content/uploads/2024/06/Calorie-restriction-lifespan-curve-2048x1152.png 2048w" sizes="(max-width: 1024px) 100vw, 1024px" /><figcaption class="wp-element-caption">Values related to metabolic health – insulin and glucose response to intravenous glucose challenge of 9-12 year old control-fed (CF) and calorie restricted (DR) Labrador retriever dogs from Table 3. Lawler et al., Br J Nutr. 2008;99(4):793–805.</figcaption></figure>







<h2 class="wp-block-heading">Caloric restriction can be difficult to sustain long-term</h2>



Dramatic, lifelong caloric restriction is not a practical method of extending lifespan and healthspan in dogs. Without appropriate diet formulation and close monitoring, it is easy to cause malnutrition, which can undermine the potential benefits and even be directly harmful. Feeding is also an important element in the human-animal bond, and asking owners to drastically restrict their dogs’ caloric intake for life can interfere with this bond and the success of the human-dog relationship.



Additionally, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5806590/">obesity is a tremendous and growing problem</a> in companion dogs. It’s hard enough to feed our dogs appropriately to maintain a healthy weight, so choosing to severely restrict their food intake even to obtain significant lifespan and health benefits seems unlikely to be possible for most of us.&nbsp;







<h2 class="wp-block-heading">Alternatives to caloric restriction — what Loyal is working towards</h2>



Fortunately, there may be alternatives to caloric restriction for improving the lifespan and healthspan of dogs. Studies of caloric restriction have taught us a lot about the fundamental biology of aging, and there are many potential means to achieve some of the benefits of caloric restriction other than feeding dramatically less food to our dogs. Promising avenues of future research may include diets with different composition, the timing of feeding, and medicines that mimic aspects of the physiologic response (and positive effects) of caloric restriction.&nbsp;



While no clearly effective longevity therapy is yet available, science has already proven that aging can be influenced. There are many different ongoing research efforts aiming to translate the decades of knowledge concerning aging biology into more, healthier years for our dogs — including what we’re working on at Loyal! Science will ultimately tell us which, if any, will work and what the relative risks and benefits will be, as is always the case, but having a plausible hypothesis and established potential mechanisms is a good first step.







<h2 class="wp-block-heading">Sources</h2>



<ol class="wp-block-list">
<li>Kenyon, C., Chang, J., Gensch, E. et al. A C. elegans mutant that lives twice as long as wild type. Nature 366, 461–464 (1993). <a href="https://doi.org/10.1038/366461a0">https://doi.org/10.1038/366461a0</a></li>



<li>Mair W, Goymer P, Pletcher SD, Partridge L. Demography of dietary restriction and death in Drosophila. Science. 2003 Sep 19;301(5640):1731-3. doi: <a href="https://www.science.org/doi/10.1126/science.1086016">10.1126/science.1086016</a>. PMID: 14500985.</li>



<li>Mao K, Quipildor GF, Tabrizian T, Novaj A, Guan F, Walters RO, Delahaye F, Hubbard GB, Ikeno Y, Ejima K, Li P, Allison DB, Salimi-Moosavi H, Beltran PJ, Cohen P, Barzilai N, Huffman DM. Late-life targeting of the IGF-1 receptor improves healthspan and lifespan in female mice. Nat Commun. 2018 Jun 19;9(1):2394. doi: <a href="https://doi.org/10.1038/s41467-018-04805-5">10.1038/s41467-018-04805-5</a></li>



<li>Kealy RD, Lawler DF, Ballam JM, Mantz SL, Biery DN, Greeley EH, Lust G, Segre M, Smith GK, Stowe HD. Effects of diet restriction on life span and age-related changes in dogs. J Am Vet Med Assoc. 2002 May 1;220(9):1315-20. doi: <a href="https://pubmed.ncbi.nlm.nih.gov/11991408/">10.2460/javma.2002.220.1315</a>. PMID: 11991408.</li>



<li>Lawler DF, Larson BT, Ballam JM, et al. Diet restriction and ageing in the dog: major observations over two decades. Br J Nutr. 2008;99(4):793–805. doi:<a href="https://doi.org/10.1017/S0007114507871686">10.1017/S0007114507871686</a></li>
</ol>

Dogs age physically and functionally as they get older, but these changes are not solely due to the passage of time or the body “wearing out”. 

There are two broad ways to look at the causes of aging: why should physical aging happen at all, and what specific mechanisms lead to the changes we see in aging dogs? The first question is often answered in terms of evolutionary and developmental biology and why it can lead to animals experiencing deterioration and death with age. The second question focuses more on the biological events that happen in an individual body that lead to this deterioration, and what we might do to change these events and delay aging.

Many theories have been proposed for why animals experience aging at all. The oldest notion is simply the “wear and tear” hypothesis. It seems logical that our physical bodies should wear out over time. It was once thought that each individual only had a limited number of heartbeats before the heart became too damaged to function, or that too much activity caused cumulative damage to joints, resulting in arthritis. 

However, living animals have systems for repairing and regenerating tissue. We now know that exercise actually extends life and preserves function, partly because it stimulates these systems for repairing and maintaining the body. Mechanical wear-and-tear turns out to be a relatively minor factor in aging.

It is true, of course, that some kinds of damage do accumulate over time. Injuries and imperfect healing can lead to dysfunction later in life. Damage to DNA or proteins can build up over the years and cause body systems to lose or have decreased functionality. The idea of damage accumulating over time has some truth to it, but overall, it is too simplistic and can’t explain many important aspects of how dogs age.

A more sophisticated idea for why animals age is the “rate of living” theory. Scientists have found a general relationship among animal species between body size and lifespan. Larger species tend to live longer than smaller ones. Part of the reason for this may be that smaller species have a faster metabolic rate; they use more energy and more fuel than bigger species because all their bodily functions run faster. This higher metabolic rate leads to greater production of damaging by-products, such as free radicals, and thus, faster accumulation of damage and breakdown of body functions. These smaller species literally live fast and die young compared to larger creatures!

A classic example would be the differences between a mouse and an elephant. Although the elephant is a lot bigger, and so needs a lot more food overall, the mouse actually consumes and uses a lot more calories than the elephant relative to its body size. Its heart rate and breathing rate and every other aspect of its bodily functions run much faster than those of an elephant. As a result, mice age faster and die younger than elephants.

The rate of living theory works pretty well as a general principle, but there are plenty of exceptions, and it doesn’t perfectly explain differences in aging between or within species. In fact, larger individuals within a species tend to have shorter lifespans. This difference is especially exaggerated in dogs due to intensive breeding. There is still much to discover about the root causes of aging and the specific mechanisms that lead to the physical and functional changes we see as our dogs get older.

Why do dogs age?

<h2 class="wp-block-heading" id="why-dogs-age">Why Dogs Age</h2>



Dogs age physically and functionally as they get older, but these changes are not solely due to the passage of time or the body “wearing out”.&nbsp;



There are two broad ways to look at the causes of aging: why should physical aging happen at all, and what specific mechanisms lead to the changes we see in aging dogs? The first question is often answered in terms of evolutionary and developmental biology and why it can lead to animals experiencing deterioration and death with age. The second question focuses more on the biological events that happen in an individual body that lead to this deterioration, and what we might do to change these events and delay aging.







<h3 class="has-xl-font-size wp-block-heading" id="wear-and-tear" style="font-style:normal;font-weight:700">Wear and Tear</h3>



<img loading="lazy" decoding="async" src="https://lh3.googleusercontent.com/Oi6o0fNb9RaW4ly56cSWftIlEIl-OdlAv1Lzu7iYAyKme4QW9JB50xFcFqATzbpd09tZxErQ273LbmNHukC30z2fhN4zneaMG9lLFpPcaz2auych7PN60ShQQ6YYEQQ_fkYjnBX9" width="461" height="308">



Many theories have been proposed for why animals experience aging at all. The oldest notion is simply the “wear and tear” hypothesis. It seems logical that our physical bodies should wear out over time. It was once thought that each individual only had a limited number of heartbeats before the heart became too damaged to function, or that too much activity caused cumulative damage to joints, resulting in arthritis.&nbsp;



However, living animals have systems for repairing and regenerating tissue. We now know that exercise actually extends life and preserves function, partly because it stimulates these systems for repairing and maintaining the body. Mechanical wear-and-tear turns out to be a relatively minor factor in aging.



It is true, of course, that some kinds of damage do accumulate over time. Injuries and imperfect healing can lead to dysfunction later in life. Damage to DNA or proteins can build up over the years and cause body systems to lose or have decreased functionality. The idea of damage accumulating over time has some truth to it, but overall, it is too simplistic and can’t explain many important aspects of how dogs age.







<h3 class="has-xl-font-size wp-block-heading" id="rate-of-living" style="font-style:normal;font-weight:700">Rate of Living</h3>



A more sophisticated idea for why animals age is the “rate of living” theory. Scientists have found a general relationship among animal species between body size and lifespan. Larger species tend to live longer than smaller ones. Part of the reason for this may be that smaller species have a faster metabolic rate; they use more energy and more fuel than bigger species because all their bodily functions run faster. This higher metabolic rate leads to greater production of damaging by-products, such as free radicals, and thus, faster accumulation of damage and breakdown of body functions. These smaller species literally live fast and die young compared to larger creatures!



A classic example would be the differences between a mouse and an elephant. Although the elephant is a lot bigger, and so needs a lot more food overall, the mouse actually consumes and uses a lot more calories than the elephant relative to its body size. Its heart rate and breathing rate and every other aspect of its bodily functions run much faster than those of an elephant. As a result, mice age faster and die younger than elephants.



<figure class="wp-block-image"><img decoding="async" src="https://lh3.googleusercontent.com/ueo7iLqdWg7F7AWd6w70N3UYu_aCQZzAQ-ZnjqJADyR9VoLazlvJOlcvvvtLhzjmVSIlhohMYVBF2agN95NMgXGiatKnRWA7vRwPZhvnayhPckP2ocFWa49r_64udtOFitYWlC_l" alt=""/></figure>



The rate of living theory works pretty well as a general principle, but there are plenty of exceptions, and it doesn’t perfectly explain differences in aging between or within species. In fact, larger individuals within a species tend to have shorter lifespans. This difference is especially exaggerated in dogs due to intensive breeding. There is still much to discover about the root causes of aging and the specific mechanisms that lead to the physical and functional changes we see as our dogs get older.

Age-related diseases have long been thought of as inevitable, natural consequences of getting older. The traditional medical response to age related diseases such as cancer has been to detect and treat them as early as possible, to cure if possible and reduce suffering and prolong life when an illness cannot be cured. These are important and valuable approaches but in an ideal world, the best approach is always prevention.

Preventative veterinary medicine has been incredibly effective at reducing the burden of infectious disease, parasitism, malnutrition, injuries, and many other causes of suffering and death in dogs. However, the options are limited for preventing the many diseases of aging. Maintaining a healthy body weight, regular exercise, and a few other lifestyle interventions do reduce risks to some extent, but we need to turn our growing understanding of the mechanisms of aging into therapies that address aging itself.

The direct way to accomplish this is through interventions that prevent or delay the occurrence of specific age-associated diseases. If targeting particular mechanisms of aging can reduce the chances of our dogs developing cancer, for example, this would prolong life and preserve health for many individuals because cancer is a leading cause of death in aged dogs. 

However, the immediate cause of death for most dogs is not any specific disease but rather euthanasia. We choose to let our dogs go when it is clear that they are experiencing significant suffering or loss in quality of life. 

Aging also leads to a general loss of comfort, function, and resilience, a condition known as frailty. One of the greatest potential benefits of targeting the underlying mechanisms of aging would be to slow the onset of frailty. Keeping dogs biologically younger for longer evwould extend healthspan and could also indirectly lengthen life by delaying the point at which quality of life has declined so much that euthanasia is necessary. 

Immortality, of course, seems unlikely for complex biological organisms, and fatal illness or unacceptable frailty is likely inevitable for all dogs eventually. However, there is great potential to improve overall quality of life by compressing the period of significant disease and disability to as small a fraction of the lifecycle as possible and extend those prime, healthy years. 

Is aging inevitable?

Age-related diseases have long been thought of as inevitable, natural consequences of getting older. The traditional medical response to age related diseases such as cancer has been to detect and treat them as early as possible, to cure if possible and reduce suffering and prolong life when an illness cannot be cured. These are important and valuable approaches but in an ideal world, the best approach is always prevention.



Preventative veterinary medicine has been incredibly effective at reducing the burden of infectious disease, parasitism, malnutrition, injuries, and many other causes of suffering and death in dogs. However, the options are limited for preventing the many diseases of aging. Maintaining a healthy body weight, regular exercise, and a few other lifestyle interventions do reduce risks to some extent, but we need to turn our growing understanding of the mechanisms of aging into therapies that address aging itself.



The direct way to accomplish this is through interventions that prevent or delay the occurrence of specific age-associated diseases. If targeting particular mechanisms of aging can reduce the chances of our dogs developing cancer, for example, this would prolong life and preserve health for many individuals because cancer is a leading cause of death in aged dogs.&nbsp;



However, the immediate cause of death for most dogs is not any specific disease but rather euthanasia. We choose to let our dogs go when it is clear that they are experiencing significant suffering or loss in quality of life.&nbsp;



Aging also leads to a general loss of comfort, function, and resilience, a condition known as frailty. One of the greatest potential benefits of targeting the underlying mechanisms of aging would be to slow the onset of frailty. Keeping dogs biologically younger for longer evwould extend healthspan and could also indirectly lengthen life by delaying the point at which quality of life has declined so much that euthanasia is necessary.&nbsp;



Immortality, of course, seems unlikely for complex biological organisms, and fatal illness or unacceptable frailty is likely inevitable for all dogs eventually. However, there is great potential to improve overall quality of life by compressing the period of significant disease and disability to as small a fraction of the lifecycle as possible and extend those prime, healthy years.&nbsp;