]WHAT IS AGING?
How we define aging depends on our goals and our frame of reference. From the biomedical perspective of the veterinary clinician, the important elements are:

• The passage of time
• Deleterious physiologic and functional changes at the molecular, cellular, tissue, and organismal levels
• A progressive increase in the risk of the three Ds
  • Disability
  • Disease
  • Death

As dogs age, they lose robustness (the ability to maintain a state of baseline or optimal physiologic function in the face of external stressors) and resilience (the ability to return to this state 

following perturbations caused by such stressors).¹ This leads to frailty and the development of many age-associated diseases which seem superficially unrelated but which are actually all consequences of the same underlying mechanisms of aging. 

IS AGING A DISEASE?
Because aging is a universal phenomenon, at least in mammals, and because historically there have been no effective interventions to slow or stop the aging process per se, only treatments to mitigate the clinical consequences, aging is widely seen as natural, inevitable, and immutable. However, decades of foundational research in laboratory model species, and more limited recent studies in humans and companion dogs, suggest that the core mechanisms of aging can be altered in a way that may prevent the health consequences of aging.^2,3 Much debate has focused on the semantic issue of whether or not something natural and ubiquitous but also responsible for illness and death should be labeled a disease.⁴ There is not yet any consensus resolution to this debate.

A pragmatic approach that avoids this semantic debate is to view aging is the most important modifiable risk factor for disease in companion dogs. This is a familiar concept to veterinarians. Obesity, for example, is a risk factor for multiple specific diseases which increases the overall risk of mortality.⁵ Focusing on reducing this risk by targeting obesity, rather than waiting for the clinical consequences to develop and then managing each independently is a well-established practice in preventative medicine.

Age-associated changes are responsible for most of the health problems of adult dogs, and there are plausible hypotheses suggesting therapies that could directly target aging and so prevent these problems. The focus of geroscience (the study of the fundamental mechanisms of aging) is to identify these targets and therapies so the field of geriatrics (the clinical management of the aged) can move away from the reactive practice of treating the clinical consequences of aging as they arise and towards a preventative approach of delaying and preventing these consequences by modifying the fundamental processes of aging. 

CANINE GERIATRIC SYNDROME
Regardless of whether one chooses to think of aging as a disease, it is useful to characterize and measure the key elements of canine aging process, including the underlying mechanisms and the clinical phenotype. Canine Geriatric Syndrome (CGS) is both a conceptual framework to organize canine geroscience research and also a potential clinical assessment tool to help determine biological age and predict health outcomes in aging dogs. Figure 1 illustrates the components of CGS.

The fundamental mechanisms of aging, from the cellular and molecular level to the level of tissues and organs, generate a phenotype that includes physical, function, behavioral and metabolic changes. These culminate in frailty, which dimmish quality of life, burden human caregivers, and eventually lead to the key negative health outcomes: disability, disease, and death. Currently, this syndrome serves primarily as a scaffold focusing research to better understand the causes and manifestations of canine aging. Eventually, clinical assessment of the syndrome will be possible, leading to a diagnosis of CGS that quantifies the biological age of individuals, predicts morbidity and mortality, and guides clinical intervention.

HOW DO DOGS AGE?
The cellular and molecular processes associated with aging, and the tissue dysfunction and ultimate health problems that result from these processes, are complex and multifactorial. Research in laboratory species, and in humans and our canine companions, has elucidated many of these mechanisms, and our understanding of them is growing rapidly. Typical changes include diminished stem cell number and function, declining mitochondrial number and function, accumulation of aberrant and dysfunctional proteins, and many others.^1,6–8

Despite the complexity of aging, it is ultimately just biology, a collection of physiologic processes that can be understood and manipulated like any other.  There is a vibrant field of canine geroscience research investigating the processes of aging and potential targets for intervention to extend healthspan and lifespan. 

Aging manifests in many visible physical changes, from greying of the coat to lenticular sclerosis and loss of lean body mass. Functional changes include decreased mobility and diminished hearing and vision.  Behaviorally, old dogs are often less active, less social, and more prone to anxiety and confusion, with many eventually developing canine cognitive dysfunction, a brain disorder similar in many ways to Alzheimer’s Disease in humans. 

WHEN IS A DOG “OLD”?
The old canard that every year in a dog’s life is equivalent to seven years for a human is a misleading oversimplification. Dogs age more rapidly than humans at the beginning and end of their life cycles, but the overall lifespan trajectory is quite similar.⁹ Large and small dogs often age quite differently as well, so the designation of geriatric status may be appropriate much earlier for some breeds than others. In terms of chronological age, or simply the time a dog has been alive, one has to consider size, breed, and individual characteristics. For practical purposes, this approximation is at least useful for triggering more intensive monitoring and investigation of clinical complaints, but it is merely a very rough guide to when we might call a dog “old:”

• Small  (under 20 lbs) > 12 years
• Medium (20-50 lbs) > 10 years
• Large (over 50 lbs) > 8 years

More important than chronological age, however, is biological age, defined as the degree to which aging has impacted the robustness, resilience, and state of health and function in an individual as measured by physical, functional, and biomarker assessment.¹ We do not yet have reliable tools for measuring biological age, but many are being developed and tested, and ultimately this will be a much more accurate way to predict the age-associated risk of the three Ds (disability, disease, and death) than chronological age.

AGE-ASSOCIATED DISEASES AND CLINICAL PROBLEMS
Most categories of disease become more common in older dogs, including neoplasia, degenerative musculoskeletal diseases (e.g. osteoarthritis and sarcopenia), cardiac disease (e.g. myxomatous mitral valve disease and cardiomyopathy), chronic kidney disease, and others. Apart from congenital disorders, infections, and trauma, most of the significant diseases and causes of death dogs experience result from the progressive accumulation of cellular and tissue changes associated with aging.

Important clinical problems often develop which are not always associated with a specific diagnosis of disease. Loss of mobility, pain, sensory and cognitive decline, and many other such aging changes diminish quality of life, increase caregiver burden, and eventually lead to euthanasia. The common view of these as “natural” and inevitable part of the lifecycle impedes appropriate assessment and management of these conditions and delays necessary research to develop preventative interventions to extend healthspan.

A SYSTEMATIC APPROACH TO ASSESSMENT & MANAGEMENT OF GERIATRIC DOGS
Once age-associated health problems do develop, we can best care for our patients with systematic, rational, evidence-based assessment and management. There are many tools that allow us to evaluate pain, impaired mobility, frailty, and other manifestations of canine aging, and these are not yet widely and consistently used. Many of the most common age-associated diseases, such as chronic kidney disease, cardiac disease, and many types of neoplasia, have been the focus of extensive research, and there are often clinical practice guidelines and other evidence-based tools to help support high-quality therapeutic management of these conditions.^13–15 And finally, despite some significant limitations, the emerging discipline of hospice and palliative care is an important element in caring for those patients most severely affected by aging.¹⁶

ASSESSMENT AND MANAGEMENT TOOLS
An important part of a systematic approach to geriatric dogs is consistent, objective assessment and management of age-related diseases and clinical problems. This is best accomplished with the regular use of validated clinical metrology instruments and reliance, when possible, on evidence-based clinical practice guidelines. There are many CMIs available to quantify pain, mobility, frailty, quality of life, and the burden of care on the owners of geriatric dogs. Repeated use of these allows detection of changes over time, better evaluation of the effectiveness of therapies than unaided observation, and better communication with owners to facilitate decision making. 

There are also numerous clinical practice guidelines available to support management of the most common age-associated problems and diseases. While some are more rigorous and evidence-based than others, all offer rational and systematic approaches that can help clinicians make comprehensive treatment and management plans.

PITFALLS IN CANINE GERIATRICS
A systematic approach to geriatric medicine encourages proactive identification of disease and clinical problems and using the best available evidence to guide diagnostic and treatment interventions. Too often, clinical signs of frailty and disease are dismissed as “just slowing down” or “normal aging” rather than appropriately assessed, monitored, and managed. In the future, proactive and systematic detection of such signs will be a critical element in the determination of biological age and the decision to employ therapies targeting aging directly.

References

1.       McKenzie BA, Chen FL, Gruen ME, Olby NJ. Canine Geriatric Syndrome: A Framework for Advancing Research in Veterinary Geroscience. Front Vet Sci. 2022;0:462. doi:10.3389/FVETS.2022.853743

2.       Campisi J, Kapahi P, Lithgow GJ, Melov S, Newman JC, Verdin E. From discoveries in ageing research to therapeutics for healthy ageing. Nat 2019 5717764. 2019;571(7764):183-192. doi:10.1038/s41586-019-1365-2

3.       Lawler DF, Evans RH, Larson BT, Spitznagel EL, Ellersieck MR, Kealy RD. Influence of lifetime food restriction on causes, time, and predictors of death in dogs. J Am Vet Med Assoc. 2005;226(2):225-231. doi:10.2460/javma.2005.226.225

4.       McKenzie BA. Is Aging a Disease? DVM360. 2022;53(3):25.

5.       Salt C, Morris PJ, Wilson D, Lund EM, German AJ. Association between life span and body condition in neutered client-owned dogs. J Vet Intern Med. 2019;33(1):89-99. doi:10.1111/JVIM.15367

6.       López-Otín C, Blasco MA, Partridge L, Serrano M, Kroemer G. The hallmarks of aging. Cell. 2013;153(6):1194-1217. doi:10.1016/j.cell.2013.05.039

7.       Sándor S, Kubinyi E. Genetic Pathways of Aging and Their Relevance in the Dog as a Natural Model of Human Aging. Front Genet. 2019;10:948. doi:10.3389/fgene.2019.00948

8.       McKenzie BA. Comparative veterinary geroscience: mechanism of molecular, cellular, and tissue aging in humans, laboratory animal models, and companion dogs and cats. Am J Vet Res. 2022;83(6). doi:10.2460/AJVR.22.02.0027

9.       Wang T, Ma J, Hogan AN, et al. Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome. Cell Syst. 2020;11(2):176-185.e6. doi:10.1016/j.cels.2020.06.006

10.     Salt C, Morris PJ, Wilson D, Lund EM, German AJ. Association between life span and body condition in neutered client-owned dogs. J Vet Intern Med. 2019;33(1):89-99. doi:10.1111/JVIM.15367

11.     McKenzie BA. What does the evidence say about feline fitness and dog aerobics? Vet Pract News. Published online January 2022:25-26.

12.     Urfer SR, Wang M, Yang M, Lund EM, Lefebvre SL. Risk Factors Associated with Lifespan in Pet Dogs Evaluated in Primary Care Veterinary Hospitals. J Am Anim Hosp Assoc. 2019;55(3):130-137. doi:10.5326/JAAHA-MS-6763

13.     (IRIS) IRIS. Treatment Recommendations for CKD in Dogs.; 2019.

14.     Keene BW, Atkins CE, Bonagura JD, et al. ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs. J Vet Intern Med. 2019;33(3):1127-1140. doi:10.1111/jvim.15488

15.     Biller B, Patel M, Smith D, Bryan C. 2016 AAHA Oncology Guidelines for Dogs and Cats*. J Am Anim Hosp Assoc. 2016;52:181-204. doi:10.5326/JAAHA-MS-6570

16.     Bishop G, Cooney K, Cox S, et al. 2016 AAHA/IAAHPC End-of-Life Care Guidelines. J Am Anim Hosp Assoc. 2016;52(6):341-356. doi:10.5326/JAAHA-MS-6637)

SUMMARY INCLUDING 5 KEY “TAKE HOME” POINTS

1. Aging is not an inevitable and immutable fact of life. It is a modifiable risk factor for the most causes of disability, disease, and death in adult dogs.
2. Canine Geriatric Syndrome describes the physical, function, behavioral, and metabolic changes that occur in aging dogs that lead to clinical disease, frailty, diminished quality of life, and a significant caregiver burden on dog owners.
3. Aging is just biology! The cellular, molecular, and tissue changes that occur, and that lead to Canine Geriatric Syndrome, are complex but comprehensible. The better we understand these changes, the better we can intervene to mitigate them.
4. A systematic, evidence-based approach to assessment and management of diseases and clinical problems in geriatric dogs, supported by validated clinical metrology instruments and clinical practice guidelines, is a more efficient, comprehensive, and effective strategy for high-quality patient care.
   

EVIDENCE-BASED MEDICINE
There are many characterizations of evidence-based medicine (EBM),^1–3 but nearly all include the following core elements:

• Explicit integration of controlled research evidence into clinical decision-making
• Acknowledgement that some types of evidence are more reliable than others. This is frequently illustrated with hierarchical structures such as evidence pyramids, as in Figure 1. 
• Recognition that evidence generated by controlled scientific research is generally superior to anecdotal evidence and uncontrolled experience or observation.
• A pragmatic acceptance that clinical decisions must be based on the best available evidence, regardless of the level, and should incorporate the judgement of the clinician and the goals and resources of key stakeholders (e.g. human patients or veterinary clients).

Figure 1. Hierarchy of evidence, from most available and least reliable at the bottom to most reliable and least available at the top.⁴

EBM is a powerful tool for improving patient care, reducing medical errors, compensating for cognitive biases and other sources of faulty decision-making, and meeting the ethical obligations of clinicians to provide the most effective possible treatment and to obtain true informed consent. The major limitations of EBM in veterinary medicine include the paucity of high-quality scientific evidence and a culture of reliance on anecdote and personal experience rather than controlled research evidence.

VETERINARY PALLIATIVE AND HOSPICE CARE
The clinical practice guidelines of the International Association of Animal Hospice and Palliative Care (IAAHPC) define palliative care as “relieving or soothing the symptoms of a disease or disorder at any stage of an illness.”⁵ The American Animal Hospital Association (AAHA) End of Life Guidelines define it as “treatment that supports or improves the quality of life (QOL) for patients and caregivers by relieving suffering.”⁶ The focus is symptomatic treatment to relieve suffering and improve quality of life, regardless of whether the cause of suffering is a terminal or curable condition. This is, or should be, an integral part of the ordinary practice of veterinary medicine, not relevant only to end of life care.

Hospice, on the other hand, is specific to patients with terminal or incurable conditions, and it is less straightforward to define. According to the AAHA guidelines, it is “philosophy or program of care that addresses the physical, emotional, and social needs of animals in the advanced stages of a progressive, life-limiting illness or disability.”⁶  

The IAAHPC does not provide a single definition, instead discussing the origins and various elements of animal hospice and how it is similar and different from human hospice care. These discussions include the following key concepts:⁵

• Provide palliative care not only for the imminently dying, but also for patients for whom a cure is no longer possible and whose condition has become advanced, progressive, and incurable
• Give patients and caregivers control, dignity, and comfort during the time they have remaining to live
• Offer spiritual support to patients and accommodates beliefs about death and about afterlife as much as possible. It also provides spiritual and grief support for caregivers 
• Including hospice-­supported natural death as well as euthanasia. 

EBM APPLIED TO PALLIATIVE AND HOSPICE CARE
Both the AAHA and IAAHPC guidelines, as well as most books and training materials for veterinary professionals dealing with hospice and palliative care, acknowledge the importance of EBM for these disciplines:

• AAHA-⁶
  • Evidence-based support for specific recommendations has been cited whenever possible and appropriate 
  • Because each case is different, veterinarians must base their decisions and actions on the best available scientific evidence, in conjunction with their own expertise, knowledge, and experience. 
  • Evidence-based research to support this rapidly evolving field is also necessary. 
    
• IAAHPC-⁵
  • Applying insights and knowledge from bioethics will expedite the development of evidence­-based best practices in these emerging fields. 
  • The fields of animal hospice and palliative care are still in the early stages of development and these Guidelines will require revision as evidence­-based knowledge advances. 

However, organizations and experts in this field also acknowledge that there is a deficiency in the evidence base for many of the practices commonly recommended and employed and that personal experience and extrapolation from human medicine or basic science, both examples of very low-level evidence, form the support for many of the day-to-day interventions and techniques used. This is, of course, also true in most other disciplines within veterinary medicine.

The lack of strong evidence supporting the effectiveness of many practices in hospice and palliative care diminishes the quality of patient care. The history of human and veterinary medicine is rife with ineffective and even actively harmful treatments that were believed to be safe and effective and were widely used for long periods of time before scientific study demonstrated their deficiencies. From bloodletting and homeopathy to thalidomide and internal mammary artery ligation, therapies supported by personal experience and low-quality evidence have been failing patients for thousands of years.^7,8

Perhaps a greater challenge to more evidence-based palliative and hospice care than the current lack of high-level evidence is the centrality of philosophical, ethical, and spiritual considerations in these fields. In human hospice, the goals of a hospice program, and the success of hospice and palliative care in any individual case, are inherently intertwined with the beliefs and values of the humans involved. This is an explicit feature of human hospice, where the spiritual beliefs of the human patient and family members are key drivers of the hospice plan for an individual. 

Central tenets of the human hospice movement are predicated on contemporary cultural and religious beliefs. For example, a common guiding principle is that hospice care should never hasten death,⁹ and this is largely a response to general societal views about the sanctity of life and prohibitions on euthanasia, which are rooted in religious and spiritual belief systems.

The animal hospice movement recognizes that veterinary professionals operate in a different context. Our patients cannot express philosophical or spiritual beliefs, and it is debatable whether they are capable of entertaining such beliefs or whether non-human animal cognition encompasses concepts such as the meaning of life or the existence of an “afterlife” of some sort. Euthanasia is also universally legal and widely considered an appropriate choice for animals with impaired quality of life or incurable disease, which provides a very different possible endpoint for hospice care than is usually available for humans.^5,6

However, the feelings and belief systems of our patients’ human caregivers are certainly relevant to the formulation and implementation of palliative and hospice care. Philosophical and emotional motivations for choosing natural death rather than euthanasia are likely a significant reason for seeking animal hospice care. The acceptance or rejection of specific treatments is also often informed by such beliefs, which sets limits on the options available to the veterinary team.

EBM is not readily applicable to most religious or ethical issues. When or whether it is acceptable to euthanize an individual animal or permit a natural death, for example, is not a question scientific evidence is well-suited to settle. And while scientific evidence is useful to inform our understanding of how animals experience pain and other forms of physical suffering, it cannot clearly answer existential questions about what meaning life may have to our patients or whether spiritual considerations are relevant to them. The complex ethical balancing of the interests of the patient as understood by the veterinary team and the understanding and interests of the patient’s human family relies more on the domains of ethics and philosophy than on medical scientific research. 

Ethical and philosophical issues are relative to one’s particular world view, and this will vary significantly between groups and individuals. Because the community of veterinary professionals actively working in hospice and palliative care is relatively small, the practices and guidelines within the field are heavily influenced by the beliefs and perspectives of a limited number of individuals. This may make the principles and practices of the discipline less compatible with other points of view and could discourage some veterinary professionals or animal owners from  providing or seeking palliative and hospice care or taking full advantage of its benefits. As the field grows, a broader range of perspectives may have a beneficial effect on the core principles and common practice.

There are, of course, many aspects of palliative and hospice care to which EBM can and should apply. The safety and efficacy of individual therapies, the most effective way to measure pain and other forms of physical discomfort and to assess the impact of therapies on these, and other important elements of effective palliative and hospice care do depend on accurate knowledge of the kind most effectively generated by controlled scientific research. While there are unique issues in hospice care that influence how we study such questions, there is no doubt that providing effective care requires that the veterinary team and the patients’ caregivers have an accurate understanding of the diseases, symptoms, and treatments involved.

One area that reflects the influence of belief systems and personal experience and the lack of strong EBM standards is the incorporation of so-called complementary and alternative therapies in hospice care. Despite the lack of high-quality evidence for the safety and efficacy of most of these interventions, and strong negative evidence against some, they are widely utilized in both human and animal hospice. Though not mentioned directly in the AAHA guidelines, such alternative practices are explicitly endorsed in the IAAHPC guidelines.^5,6

The culture of alternative medicine emphasizes the primacy of personal experience over empirical scientific evidence in evaluating medical treatments, and the role of spiritual considerations in healthcare is often seen as critical.¹⁰ These views are also part of the culture of end-of-life care in both human and animal hospice. The training materials for the AAHA certification program in palliative and hospice care explicitly endorse therapies with questionable supporting evidence (e.g. herbal remedies and acupuncture) and those which are clearly only placebos (e.g. homeopathy and “energy” therapies) alongside science-based medical practices. This acceptance of dubious medical practices is likely encouraged by several features of the animal hospice culture and context:

• The limited scientific evidence available to assess many common practices
• The practical and ethical challenges of conducting high-quality research in patients with terminal conditions
• The misperception that the risk of using therapies with inadequate evidence for safety and efficacy are lower in patients with terminal conditions than in patients we hope to cure
• The influence of the personal beliefs and experiences of the relatively small number of individuals involved in developing and promoting animal hospice
• The culture of the hospice movement, which emphasizes the primacy of individual experiences and beliefs and the centrality of spiritual considerations

TOWARDS MORE EVIDENCE-BASED PALLIATIVE AND HOSPICE CARE
High-quality palliative and hospice care for veterinary patients is a critical part of a holistic approach to maximizing animal welfare throughout all life stages. The more evidence-based our treatments and practices are, the more confident we can be that these truly benefit our patients. While scientific research may not always be useful in informing all aspects of end-of-life care, such as supporting the spiritual needs of our clients, it is crucial to ensuring that we understand and meet the physical and behavioral needs of patients. Veterinary professionals and animal owners, like all humans, are easily misled by cognitive biases and placebo effects into inaccurate understandings of nature and the impact of our actions, and EBM can help us avoid such errors and provide the best possible care.¹¹

Steps towards making animal hospice and palliative care more evidence based may include:

• Continued recognition of the need for more and better-quality evidence to support palliative and hospice care practices
• Improved understanding of the strengths and limitations of different types of evidence and the need to proportion our confidence in specific interventions or beliefs to the strength of the available evidence
• Creativity and persistence in the generation of reliable scientific research evidence within the limitations of the palliative and hospice care context
• Inclusion of a greater variety of perspectives and world views in establishing guidelines and training for hospice providers to maximize the value of these resources for the broadest possible population of veterinary professionals and animal caregivers
• Willingness to change and abandon specific practices based on the best available evidence

REFERENCES

1.       Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn’t. BMJ. 1996;312(7023):71-72. Accessed October 23, 2014. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2349778&tool=pmcentrez&rendertype=abstract

2.       Mckenzie B. Evidence-based veterinary medicine: What is it and why does it matter? Equine Vet Educ. 2014;26(9). doi:10.1111/eve.12216

3.       Cockroft P, Holmes M. Handbook of Evidence-Based Veterinary Medicine. (Cockcroft PD, Holmes MA, eds.). Blackwell Publishing Ltd; 2003. doi:10.1002/9780470690833

4.       McKenzie B. Evidence-based Veterinary Medicine and Personal Bias. In: Ackerman L, ed. Pet-Specific Care for the Veterinary Team. John Wiley & Sons, Inc; 2021:39-42.

5.       Shanan, A. August, K. Cooney, K. Hendrix, L. Mader, B. Pierce J. Animal Hospice and Palliative Care Guidelines.; 2009.

6.       Bishop G, Cooney K, Cox S, et al. 2016 AAHA/IAAHPC End-of-Life Care Guidelines. J Am Anim Hosp Assoc. 2016;52(6):341-356. doi:10.5326/JAAHA-MS-6637)

7.       McKenzie B. Placebos for Pets: The Truth About Alternative Medicine for Animals. Ockham Publishing; 2019.

8.       Herrera-Perez D, Haslam A, Crain T, et al. A comprehensive review of randomized clinical trials in three medical journals reveals 396 medical reversals. Elife. 2019;8. doi:10.7554/eLife.45183

9.       Finlay I. End-of-life care means exactly what it says: palliative care is about care at the end of life, not about ending life. Futur Healthc J. 2018;5(1):35. doi:10.7861/FUTUREHOSP.5-1-35

10.     McKenzie BA. Is complementary and alternative medicine compatible with evidence-based medicine? J Am Vet Med Assoc. 2012;241(4). doi:10.2460/javma.241.4.421

11.     McKenzie BA. Veterinary clinical decision-making: cognitive biases, external constraints, and strategies for improvement. J Am Vet Med Assoc. 2014;244(3):271-276. doi:10.2460/javma.244.3.271

INTRODUCTION
Experienced clinicians often have an enormous knowledge base about the health problems their patients present with and the available diagnostic and therapeutic options. This knowledge is built over time from a variety of sources: basic pathophysiology and clinical information learned in school; practice tips and pearls imparted by professors and speakers at continuing education meetings; review articles and primary research papers in veterinary journals; textbooks; advice from mentors and colleagues in practice; and, of course, clinical experience with previous cases. 

This knowledge base smoothly and efficiently informs the day-to-day activities of clinical practice. When cases with familiar features are seen, the appropriate diagnostic and treatment steps often come to mind automatically, or with minimal prodding. Unlike students and new graduates, experienced clinicians often have little sense of dredging up facts committed to memory and more of a sense of simply knowing things. One of the hallmarks of expertise is that the collating of observations and relevant knowledge into a coherent picture of the problem and a plan become less deliberate and more automatic with time.¹

While this process, which is a universal and automatic feature of how the human brain functions, leads to greater efficiency than the explicit, conscious use of algorithms and reference sources employed by less experienced practitioners, it has some serious limitations. One problem, for example, is that the knowledge one relies on often can no longer be connected to its original source. We often simply know things without being aware of how we came to know them. This limits our ability to judge the reliability of the source of our knowledge. In fact, such established, automatic knowing often generates a sense of certainty greater than that which accompanies deliberately seeking and finding information.² We are more likely to trust what we already know, even if we don’t remember where we learned it, than we are to trust what we have just discovered after searching a trustworthy source of information.

There are also a large number of well-characterized cognitive biases and sources of errors inherent in how our brains acquire, process, store, and utilize information that can lead us astray.³ These are more likely to create error when our reasoning is automatic rather than deliberate, as it necessarily must be in an efficient clinical environment that is not devoted primarily to teaching. 

One of the major functions of evidence-based veterinary medicine (EBVM) is to provide tools and resources to make the knowledge base we employ more reliable. This includes generating better quality information through research and facilitating the integration of that information into clinical decision making. When the relevant evidence is of high quality, this can add confidence to our decisions.

More commonly, when the evidence has significant limitations, we may end up with less confidence in our knowledge than we would have without an explicit evaluation of the evidence. However, this is not as undesirable an outcome as it may appear. A clear, accurate understanding of the uncertainty associated with a particular practice protects us, and our patients, from the dangers of acting with unjustified confidence. We are more likely to weigh thoughtfully the risks and benefits of action in the context of an individual case when we understand the degree of uncertainty about our ability to predict or manipulate the patient’s condition. 

Being clear about the sources of our knowledge, and the appropriate level of confidence to have in them, also aids in fulfilling our duty to provide clients with informed consent. Surveys of veterinary clients have shown that they value truthfulness highly in the information we provide to them, and that they want to be made aware of the uncertainties involved in the treatment of their animals.^4-5 Only if we understand the reliability and limitations of the information we employ in making our recommendations can we give clients the knowledge and guidance they need to make informed choices.

The purpose of these lectures is to examine some widespread or long-standing beliefs and practices in small animal medicine and assess their evidentiary foundations. In some cases, this may clearly validate or invalidate these beliefs. In most cases, however, such an exploration will likely not lead to greater certainty but to a clearer understanding of the degree of uncertainty associated with these beliefs. Hopefully, this will be useful in making clinical decisions and in communicating with clients. The exercise may also be useful in illustrating how to make use of the research literature in establishing and maintaining the knowledge base that informs one’s clinical practice.

Some of the topics that will be covered include:

1. Metronidazole as a treatment for diarrhea
2. Tramadol as an oral analgesic
3. Vitamin C and steroids in sepsis
4. Common use of gastroprotectants 

REFERENCES

1. Benner, P. From novice to expert. Amer J Nursing, 1982; 82(3):402-7.

• Burton, R. On Being Certain: Believing You’re Right Even When You’re Not. New York: St. Martin’s Press. 2008

• McKenzie, BA. Veterinary clinical decision-making: cognitive biases, external constraints, and strategies for improvement. J Amer Vet Med Assoc. 2014;244(3):271-276.

• Mellanby RJ, Crisp J, De Palma G, et al. Perceptions of veterinarians

and clients to expressions of clinical uncertainty. J Small

Anim Pract 2007;48:26–31.

• Stoewen DL, et al.  (2014) Qualitative study of the information expectations of clients accessing oncology care at a tertiary referral center for dogs with life-limiting cancer. J Am Vet Med Assoc. 2014;245(7):773-83.