Dog Health & Longevity Glossary

Plain-language definitions of veterinary, genetic, and longevity science terms used across this site. 120 terms defined.

A

Adaptogens Nutrition & Supplements: A class of botanical compounds that modulate the stress response by normalizing hypothalamic-pituitary-adrenal (HPA) axis activity. Adaptogens are proposed to increase resilience to physical and psychological stressors, though canine-specific evidence remains limited.
Albumin Testing & Diagnostics: The most abundant protein in blood plasma, produced by the liver. Albumin maintains oncotic pressure, transports hormones and drugs, and serves as a clinical marker of liver function, nutritional status, and protein-losing diseases.
Allele Genetics: A variant form of a gene occupying a specific position (locus) on a chromosome. Dogs inherit two alleles for each gene — one from each parent — and the combination determines traits such as coat color, size, and disease susceptibility.
Anemia Health Conditions: A reduction in the number of red blood cells or hemoglobin concentration in the blood, resulting in decreased oxygen-carrying capacity. Anemia is a clinical finding, not a diagnosis — it always indicates an underlying condition requiring investigation.
Anesthesia Treatments & Procedures: A medically induced state of controlled unconsciousness, analgesia, and muscle relaxation. In dogs, general anesthesia is required for surgery, dental procedures, and some diagnostic imaging. Pre-operative assessment reduces risk, particularly in senior dogs.
Antioxidant Nutrition & Supplements: A molecule that neutralizes reactive oxygen species (ROS) and prevents oxidative damage to cellular structures. Antioxidants — both endogenous and dietary — play a central role in slowing age-related cellular deterioration.
Apoptosis Anatomy & Physiology: Programmed cell death — an orderly, genetically controlled process by which damaged or unnecessary cells self-destruct without triggering inflammation. Dysregulated apoptosis contributes to both cancer (too little) and tissue degeneration (too much).
Arthroscopy Treatments & Procedures: A minimally invasive surgical technique using a small camera (arthroscope) inserted through a tiny incision into a joint. Used for both diagnosis and treatment of joint conditions including fragmented coronoid process, osteochondrosis, and cruciate ligament assessment.
Articular Cartilage Anatomy & Physiology: The smooth, white connective tissue covering bone surfaces within joints. It provides a low-friction surface for joint movement and absorbs impact forces.
Autoimmune Disease Health Conditions: A category of disorders in which the immune system mistakenly attacks the body's own healthy tissues. In dogs, autoimmune diseases can target joints, blood cells, skin, thyroid, or other organs and often require lifelong immunosuppressive treatment.
Autophagy Longevity Science: Cellular self-cleaning process where damaged proteins, organelles, and cellular debris are degraded and recycled by lysosomes. Autophagy declines with age and its enhancement is a key mechanism of longevity interventions.
Autosomal Recessive Genetics: An inheritance pattern where two copies of a mutant gene (one from each parent) are required for a condition to manifest. Dogs with one copy (carriers) appear healthy but can pass the mutation to offspring.

B

Benign Health Conditions: A term describing a growth or tumor that is non-cancerous — it does not invade surrounding tissues or spread (metastasize) to other parts of the body. Benign tumors may still require treatment if they cause problems due to their size, location, or hormone production.
Bilateral Anatomy & Physiology: Affecting or relating to both sides of the body. In veterinary medicine, bilateral conditions involve paired structures on both left and right sides — such as bilateral hip dysplasia (both hips affected) or bilateral cruciate ligament rupture (both stifles affected).
Bioavailability Nutrition & Supplements: The proportion of an ingested substance (nutrient, supplement, or drug) that reaches systemic circulation in an active form. High bioavailability is essential for oral supplements to have their claimed biological effects.
Biopsy Testing & Diagnostics: The removal of a tissue sample for microscopic examination (histopathology). Biopsy provides definitive diagnosis for cancer, inflammatory disease, and organ pathology when cytology or imaging alone are insufficient.
Blood Urea Nitrogen (BUN) Testing & Diagnostics: A blood test measuring the amount of urea nitrogen — a waste product of protein metabolism — in the bloodstream. Elevated BUN can indicate kidney dysfunction, dehydration, gastrointestinal bleeding, or high-protein diet, and is routinely used alongside creatinine and SDMA to assess renal function in dogs.
Body Condition Score (BCS) Nutrition & Supplements: A standardized 9-point scale for assessing a dog's body fat and muscle mass by visual and tactile assessment. BCS 4–5/9 is considered ideal; scores above 5 indicate excess body fat.
Brachycephaly Health Conditions: A skull conformation characterized by a shortened head and flattened face, resulting from selective breeding. Brachycephalic breeds face airway obstruction, thermoregulation impairment, and reduced average lifespan compared to mesocephalic breeds.

C

C-Reactive Protein Testing & Diagnostics: An acute-phase protein produced by the liver in response to inflammation. CRP levels rise rapidly during infection, tissue injury, or systemic inflammatory disease, making it a sensitive but non-specific marker of inflammation in dogs.
Caloric Restriction Nutrition & Supplements: Reduction in total caloric intake without malnutrition. The most consistently replicated longevity intervention across species, extending lifespan in multiple animal models and strongly supported in dogs by the Purina Lifetime Study.
Cardiac Arrhythmia Health Conditions: An abnormal heart rhythm — too fast, too slow, or irregular. Arrhythmias range from clinically insignificant incidental findings to life-threatening emergencies requiring immediate intervention.
Cardiac Auscultation Testing & Diagnostics: Listening to the heart with a stethoscope to detect murmurs, arrhythmias, and abnormal heart sounds. Annual cardiac auscultation is the standard first-line screening for heart disease in all dogs.
Cardiac Output Anatomy & Physiology: The volume of blood pumped by the heart per minute, calculated as heart rate multiplied by stroke volume. Cardiac output reflects the heart's ability to meet the body's metabolic demands and declines in conditions such as dilated cardiomyopathy and congestive heart failure.
Carrier Dog Genetics: A dog carrying one normal and one mutant copy of an autosomal recessive gene. Carriers appear healthy but can pass the mutant copy to offspring, potentially producing affected puppies when bred to another carrier.
Cartilage Anatomy & Physiology: A firm but flexible connective tissue that cushions joints, forms structural frameworks (ears, nose, trachea), and provides smooth surfaces for bone movement. Articular cartilage in joints has limited capacity to heal once damaged, making its preservation a central goal in orthopedic longevity.
Cellular Senescence Longevity Science: A permanent cell cycle arrest state in which damaged cells stop dividing but remain metabolically active, secreting inflammatory signals. Accumulation of senescent cells drives tissue aging and age-related disease.
Chemotherapy Treatments & Procedures: The use of cytotoxic drugs to treat cancer by killing or slowing the growth of rapidly dividing cells. Veterinary chemotherapy protocols are designed to extend quality life with manageable side effects rather than pursue cure at any cost.
Chondroitin Sulfate Nutrition & Supplements: A sulfated glycosaminoglycan that is a major component of articular cartilage. As a supplement, chondroitin inhibits cartilage-degrading enzymes and is commonly paired with glucosamine for joint health.
Chronic Health Conditions: Describes a disease or condition that develops gradually and persists over a long period — weeks, months, or years. Chronic conditions require ongoing management rather than one-time treatment, and their cumulative impact on healthspan is often greater than acute events.
Collagen Nutrition & Supplements: The most abundant structural protein in the body, forming the framework of skin, tendons, ligaments, cartilage, and bone. Hydrolyzed collagen supplements provide bioactive peptides that may support joint and skin health in dogs.
Complete Blood Count (CBC) Testing & Diagnostics: A blood test measuring red cells, white cells, and platelets. The CBC detects anemia, infection, immune disease, and bleeding disorders — a core component of annual wellness panels for dogs.
Congenital Health Conditions: Present at birth, whether caused by genetic factors, developmental abnormalities during gestation, or environmental influences on the developing embryo. Congenital conditions may be immediately apparent or may not manifest clinically until later in life.
Creatinine Testing & Diagnostics: A waste product of muscle metabolism filtered by the kidneys and excreted in urine. Elevated serum creatinine indicates reduced kidney filtration capacity (azotemia) and is a primary marker for staging chronic kidney disease in dogs.
Cruciate Ligament Anatomy & Physiology: One of two crossing ligaments inside the stifle (knee) joint that provide front-to-back stability. The cranial cruciate ligament (CCL, equivalent to the human ACL) is the most commonly injured ligament in dogs, and its rupture is one of the leading causes of hind-limb lameness.
Cryotherapy Treatments & Procedures: The therapeutic application of cold temperatures to reduce pain, inflammation, and swelling. In veterinary medicine, cryotherapy ranges from simple ice pack application to cryosurgery for tumor ablation.
Cytokine Anatomy & Physiology: Small signaling proteins released by cells to regulate immune and inflammatory responses. Pro-inflammatory cytokines drive acute defense against infection; chronic elevation contributes to aging-related disease in dogs.
Cytology Testing & Diagnostics: The microscopic examination of individual cells collected from tissues, fluids, or masses to identify cell types, detect abnormalities, and guide diagnosis. Cytology is faster, less invasive, and less expensive than histopathology and is often the first diagnostic step for lumps, skin lesions, and body fluid analysis in dogs.

D

Degenerative Myelopathy Health Conditions: A progressive, incurable spinal cord disease in dogs caused by SOD1 gene mutations. It begins with hind limb weakness and progresses to paralysis over 6-36 months, primarily affecting older large-breed dogs.
Dermatitis Health Conditions: Inflammation of the skin, presenting as redness, itching, scaling, or lesions. Dermatitis is a descriptive term with many possible causes including allergies, infections, parasites, and immune-mediated disease.
Diuretic Treatments & Procedures: A class of drugs that increase urine production by promoting the kidneys' excretion of water and sodium. In dogs, diuretics — primarily furosemide — are essential for managing fluid overload in congestive heart failure and certain kidney and liver conditions.
DNA Panel Testing Genetics: Commercial genetic tests analyzing a dog's DNA from a cheek swab or blood sample to screen for known disease mutations, breed composition, and genetic traits. Major panels test 150–250+ conditions.
Dog Aging Project Longevity Science: The largest canine aging study ever conducted, enrolling 45,000+ companion dogs across the US. Run by University of Washington, it studies genetics, environment, and lifestyle factors affecting dog lifespan.
Dysplasia Health Conditions: Abnormal development of a tissue or organ, most commonly referring to joint dysplasia in dogs. Hip and elbow dysplasia involve malformation of joint surfaces, leading to instability, abnormal wear, and progressive osteoarthritis.

E

Echocardiogram Testing & Diagnostics: Ultrasound imaging of the heart that shows real-time cardiac structure and function. Used to diagnose and monitor heart disease in dogs, including mitral valve disease and dilated cardiomyopathy.
Electrolyte Anatomy & Physiology: Minerals in the blood and body fluids that carry an electrical charge and regulate critical physiological functions including nerve conduction, muscle contraction, hydration balance, and acid-base equilibrium. Key electrolytes in dogs include sodium, potassium, chloride, calcium, magnesium, and phosphorus.
Endoscopy Treatments & Procedures: A minimally invasive diagnostic procedure using a flexible or rigid scope with a camera and light source to visualize the interior of the gastrointestinal tract, respiratory tract, or other body cavities. Endoscopy allows direct visualization, biopsy collection, and some therapeutic interventions without surgical incision.
Epigenetic Clock Longevity Science: A biological age assessment using DNA methylation patterns that change predictably with aging. Epigenetic clocks can measure "biological age" — which may differ from chronological age based on health, lifestyle, and genetics.
Epigenetics Genetics: The study of heritable changes in gene expression that occur without alterations to the DNA sequence itself. Epigenetic modifications — including DNA methylation and histone modification — regulate which genes are active in different tissues and change predictably with age.

F

Fine-Needle Aspirate (FNA) Testing & Diagnostics: A diagnostic technique in which a thin needle is inserted into a mass, lymph node, or organ to collect cells for microscopic examination (cytology). FNA is minimally invasive, typically requires no sedation, and is the standard first step for evaluating any new lump found on a dog.

G

Gastric Anatomy & Physiology: Relating to the stomach. In veterinary medicine, gastric conditions include gastric dilatation-volvulus (bloat), gastric ulcers, gastric neoplasia, and gastric motility disorders.
Gastric Dilatation-Volvulus (GDV) Health Conditions: A life-threatening emergency where the stomach distends with gas and rotates on its axis, trapping contents and cutting off blood supply. Also called bloat. Requires emergency surgery; fatal without treatment within hours.
Glucocorticoid Treatments & Procedures: A class of steroid hormones (cortisol) and synthetic drugs (prednisone, dexamethasone) that suppress inflammation and immune responses. Glucocorticoids are among the most commonly prescribed drugs in veterinary medicine, with significant benefits and risks.
Glucosamine Nutrition & Supplements: An amino sugar naturally present in cartilage, used as an oral supplement to support joint health in dogs with osteoarthritis. Evidence for benefit is moderate; it is generally safe and widely used.
Growth Plates Anatomy & Physiology: Cartilaginous zones at the ends of long bones where new bone tissue is produced during development. In dogs, growth plates close between 12 and 24 months depending on breed size.
Gut-Brain Axis Anatomy & Physiology: The bidirectional communication network between the gastrointestinal tract and the central nervous system, mediated by the vagus nerve, immune signaling, and microbial metabolites. Gut microbiome composition influences mood, cognition, and systemic inflammation in dogs.

H

Healthspan Longevity Science: The period of life spent in good health, free from chronic disease and significant functional decline. Healthspan is increasingly considered a more meaningful longevity metric than total lifespan, as it measures quality of years rather than quantity.
Heart Murmur Grade Health Conditions: A Roman numeral scale (I–VI) rating the loudness of a heart murmur heard through a stethoscope. Higher grades generally indicate more significant disease, but echocardiography is required to determine clinical severity.
Hematocrit Testing & Diagnostics: The percentage of blood volume occupied by red blood cells, measured by centrifuging a blood sample or calculated from a complete blood count. Hematocrit (also called packed cell volume or PCV) is a primary indicator of anemia or dehydration in dogs.
Hepatic Anatomy & Physiology: Relating to the liver. Hepatic conditions encompass a wide range of diseases including chronic hepatitis, hepatic lipidosis, hepatic encephalopathy, and hepatic neoplasia. The liver's central role in metabolism, detoxification, and protein synthesis makes hepatic health critical to longevity.
Heterozygosity Genetics: The state of possessing two different alleles at a given genetic locus. Higher genome-wide heterozygosity indicates greater genetic diversity and is associated with improved health, disease resistance, and longevity in dogs.
Hip Dysplasia Score Testing & Diagnostics: The numerical or graded result from hip joint screening (OFA grades, PennHIP distraction index, or BVA/KC score). Used to assess breeding suitability and individual joint health risk.
Histopathology Testing & Diagnostics: The microscopic examination of tissue samples to diagnose disease. Histopathology provides definitive diagnosis of tumors, inflammatory conditions, and organ diseases by revealing cellular architecture and pathological changes invisible to the naked eye.
Homeostasis Anatomy & Physiology: The physiological process of maintaining stable internal conditions — temperature, pH, blood glucose, hydration, electrolyte balance — despite changes in the external environment. Age-related loss of homeostatic capacity is a hallmark of biological aging.
Hormesis Longevity Science: A biological phenomenon in which exposure to a low-dose stressor triggers adaptive protective responses that exceed what is needed to neutralize the stress, resulting in net benefit. Hormetic stressors — including exercise, fasting, and cold exposure — are proposed mechanisms behind many longevity interventions.
Hypertension Health Conditions: Abnormally elevated blood pressure. In dogs, hypertension is almost always secondary to an underlying condition such as kidney disease, Cushing's disease, or diabetes. Sustained hypertension damages target organs including the eyes, kidneys, heart, and brain.

I

IGF-1 (Insulin-Like Growth Factor 1) Longevity Science: A hormone mediating the growth effects of growth hormone. In dogs, higher lifelong IGF-1 levels correlate with larger body size and shorter lifespan. The LOY-001 drug targets excess IGF-1 in large breeds.
Immunoglobulin Anatomy & Physiology: Antibody proteins produced by B lymphocytes that recognize and bind to specific antigens (foreign molecules) to neutralize pathogens and tag them for immune destruction. The major classes in dogs are IgG, IgM, IgA, IgE, and IgD, each with distinct roles in immune defense.
Immunosuppression Treatments & Procedures: Reduced function of the immune system, either intentionally induced by drugs to treat immune-mediated diseases or occurring as a consequence of disease, malnutrition, or aging. Immunosuppressed dogs are at increased risk of opportunistic infections.
Incontinence Health Conditions: Involuntary loss of urine (urinary incontinence) or feces (fecal incontinence). Urinary incontinence is more common and often results from urethral sphincter mechanism incompetence, particularly in spayed female dogs.
Inflammation Health Conditions: The body's protective response to tissue injury or pathogen invasion, characterized by redness, heat, swelling, and pain. Chronic low-grade inflammation accelerates tissue aging and is a driver of multiple age-related diseases.
Insulin Resistance Health Conditions: A metabolic state in which cells respond poorly to insulin, requiring the pancreas to produce progressively higher amounts to maintain normal blood glucose. Insulin resistance is a precursor to type 2 diabetes, is strongly associated with obesity, and accelerates aging through chronic inflammation and metabolic dysfunction.

J

Joint Dysplasia Health Conditions: Abnormal joint development resulting in poor conformation between joint surfaces. Hip dysplasia and elbow dysplasia are the most common forms; both cause progressive osteoarthritis and pain.

K

Ketoacidosis Health Conditions: A life-threatening metabolic emergency in which severe insulin deficiency causes uncontrolled fat breakdown, producing excessive ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone) that overwhelm the body's buffering capacity and cause dangerous blood acidification. Diabetic ketoacidosis (DKA) is the most common form in dogs.

L

Laparoscopic Gastropexy Treatments & Procedures: Minimally invasive surgical technique for stomach-to-abdominal-wall attachment (gastropexy) performed through 2–3 small incisions with a camera. Preferred technique for prophylactic gastropexy due to faster recovery.
Lean Body Mass Nutrition & Supplements: The mass of a dog excluding fat tissue — comprising muscle, bone, organs, and water. Maintaining lean muscle mass in senior dogs is a primary longevity goal, as sarcopenia (muscle wasting) accelerates functional decline.
Lymphocyte Anatomy & Physiology: A type of white blood cell central to adaptive immunity, comprising T lymphocytes (cell-mediated immunity), B lymphocytes (antibody production), and natural killer cells. Lymphocytes are counted as part of a complete blood count and their numbers change in infection, stress, immune disease, and lymphoid cancers.

M

Magnetic Resonance Imaging (MRI) Testing & Diagnostics: An advanced diagnostic imaging technique that uses strong magnetic fields and radio waves to generate detailed cross-sectional images of soft tissues, the brain, spinal cord, and joints. MRI provides superior soft tissue contrast compared to radiographs or CT and is the gold standard for neurological and some orthopedic diagnoses in dogs.
Malignant Health Conditions: Describes a tumor that is cancerous — it can invade surrounding tissues, spread (metastasize) to distant sites through blood or lymphatic vessels, and recur after removal. Malignant tumors require more aggressive treatment and carry more guarded prognoses than benign growths.
Mast Cell Anatomy & Physiology: A tissue-resident immune cell that contains granules packed with histamine, heparin, and inflammatory mediators. Mast cells play essential roles in allergic responses and wound healing but are also the cell of origin for mast cell tumors — one of the most common skin cancers in dogs.
MDR1 Mutation Genetics: A mutation in the ABCB1 gene causing multi-drug resistance protein 1 deficiency. Affected dogs cannot adequately pump certain drugs out of the brain, leading to neurological toxicity at standard doses.
Metabolic Rate Anatomy & Physiology: The rate at which an organism converts nutrients to energy. Basal metabolic rate (BMR) scales with body size and correlates inversely with lifespan in dogs — smaller breeds have higher mass-specific metabolic rates but live longer.
Microbiome Anatomy & Physiology: The community of trillions of bacteria, fungi, and other microorganisms residing in the gastrointestinal tract. The gut microbiome influences digestion, immune function, inflammation, and emerging evidence links it to aging and longevity.
Mitochondria Anatomy & Physiology: Double-membrane organelles that generate adenosine triphosphate (ATP) through oxidative phosphorylation. Mitochondrial dysfunction is a hallmark of aging, contributing to reduced cellular energy, increased oxidative damage, and age-related disease.
mTOR Pathway Longevity Science: The mechanistic Target of Rapamycin signaling pathway — a central cellular regulator of growth, metabolism, and aging. mTOR inhibition by caloric restriction or rapamycin consistently extends lifespan in animal models.

N

Neoplasia Health Conditions: Abnormal, uncontrolled cell proliferation resulting in tumor formation. Neoplasia encompasses both benign growths and malignant cancers, and is the leading cause of death in dogs over 10 years of age.
NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) Treatments & Procedures: A class of drugs that reduce pain and inflammation by inhibiting COX enzymes. Veterinary NSAIDs (carprofen, meloxicam, grapiprant) are the mainstay of chronic pain management in dogs with arthritis.

O

OFA Evaluation Testing & Diagnostics: Orthopedic Foundation for Animals radiographic screening system that grades hip and elbow health in dogs. OFA certification at 24+ months is the standard pre-breeding health screen for orthopedic conditions.
Omega-3 Fatty Acids Nutrition & Supplements: Polyunsaturated fatty acids (EPA, DHA, ALA) with anti-inflammatory properties. In dogs, marine-sourced EPA and DHA are the biologically active forms supporting joint, cardiac, cognitive, and skin health.
Ossification Anatomy & Physiology: The process by which cartilage or fibrous tissue converts to bone. In developing puppies, ossification of growth plates signals skeletal maturity.
Oxidative Stress Longevity Science: An imbalance between reactive oxygen species (ROS) production and antioxidant defenses, causing cellular damage. Oxidative stress accumulates with age and contributes to multiple age-related diseases in dogs.

P

Pathology Testing & Diagnostics: The medical discipline that studies the causes and mechanisms of disease through examination of tissues, cells, and body fluids. In veterinary practice, pathology encompasses histopathology (tissue examination), cytology (cell examination), and clinical pathology (blood and fluid analysis).
PennHIP Testing & Diagnostics: University of Pennsylvania Hip Improvement Program — a radiographic method measuring passive hip joint laxity in dogs. More sensitive than OFA for detecting early hip laxity; can be performed from 16 weeks.
Phenotype Genetics: The observable physical and behavioral characteristics of an organism, resulting from the interaction between its genotype and environment. In dogs, phenotype includes size, coat, conformation, temperament, and disease expression.
Platelet Count Testing & Diagnostics: A blood test measuring the number of thrombocytes (platelets) per microliter of blood. Platelets are essential for blood clotting; abnormal counts indicate bleeding disorders, immune-mediated disease, infection, or bone marrow dysfunction.
Polymerase Chain Reaction (PCR) Testing & Diagnostics: A molecular diagnostic technique that amplifies tiny amounts of pathogen DNA or RNA to detectable levels. PCR testing provides rapid, highly sensitive detection of infectious diseases in dogs, including tick-borne, respiratory, and gastrointestinal pathogens.
Prebiotics Nutrition & Supplements: Non-digestible dietary fibers that selectively feed beneficial gut bacteria, promoting their growth and activity. Prebiotics support microbiome diversity, short-chain fatty acid production, and intestinal barrier integrity in dogs.
Probiotic Nutrition & Supplements: Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. In dogs, strain-specific probiotics support gut health, immune function, and may influence systemic inflammation.
proBNP Testing & Diagnostics: N-terminal pro-B-type natriuretic peptide — a cardiac biomarker released when heart muscle is stretched or stressed. Elevated proBNP in dogs indicates cardiac chamber enlargement and helps detect heart disease before clinical signs appear.
Prognosis Health Conditions: The predicted course and outcome of a disease — including likelihood of recovery, expected survival time, and probable quality of life. Prognosis depends on the specific condition, its stage and severity, available treatments, and the individual patient's response.
Prophylactic Gastropexy Treatments & Procedures: Surgical attachment of the stomach to the abdominal wall, performed electively before bloat (GDV) occurs in high-risk large and giant breeds. Reduces GDV risk by >95% in surgically confirmed cases.

R

Radiograph (X-ray) Testing & Diagnostics: A diagnostic imaging technique using X-rays to create two-dimensional images of internal structures. Used to evaluate bones, chest, abdomen, and joints in dogs.
Rapamycin Longevity Science: An mTOR inhibitor originally developed as an immunosuppressant that extends lifespan in multiple animal models. Being investigated for longevity effects in dogs in the Dog Aging Project's TRIAD study.
Renal Anatomy & Physiology: Relating to the kidneys. Renal function encompasses filtration of blood, waste excretion, fluid and electrolyte balance, blood pressure regulation, and hormone production (erythropoietin, active vitamin D).

S

Sarcopenia Longevity Science: Age-related progressive loss of skeletal muscle mass and strength, distinct from disease-driven cachexia. Sarcopenia reduces mobility, metabolic resilience, and quality of life in senior dogs and is an independent predictor of morbidity.
SDMA Testing & Diagnostics: Symmetric dimethylarginine — a kidney function biomarker detectable in blood. SDMA rises when approximately 25% of kidney function is lost, compared to creatinine which rises only at 75% loss, enabling much earlier CKD detection.
Senolytics Longevity Science: A class of drugs that selectively induce death of senescent cells — aged, non-dividing cells that accumulate with age and secrete inflammatory signals. Senolytic therapy aims to reduce chronic inflammation and tissue dysfunction associated with aging.
Serum Chemistry Panel Testing & Diagnostics: A blood test measuring organ function markers including kidney values (BUN, creatinine), liver enzymes (ALT, ALP), blood sugar, protein levels, and electrolytes.
Spay/Neuter (Gonadectomy) Treatments & Procedures: Surgical removal of the reproductive organs — ovariohysterectomy (spay) in females or castration (neuter) in males. Timing significantly affects cancer risk, orthopedic health, and longevity outcomes in a breed- and size-dependent manner.
Splenectomy Treatments & Procedures: Surgical removal of the spleen. In dogs, most commonly performed for splenic masses (including hemangiosarcoma) or splenic torsion. Dogs can live normally without a spleen with appropriate infection precautions.
Stem Cell Therapy Treatments & Procedures: A regenerative treatment using undifferentiated cells capable of self-renewal and differentiation into specialized tissue. In veterinary medicine, adipose-derived mesenchymal stem cells are most commonly used for osteoarthritis and tendon injuries in dogs.
Stenosis Health Conditions: Abnormal narrowing of a body passage or opening, such as a blood vessel, spinal canal, heart valve, or airway. Stenosis restricts normal flow or movement through the affected structure and can be congenital or acquired.
Synovial Fluid Anatomy & Physiology: The viscous fluid produced by the synovial membrane inside joints. It lubricates joint surfaces, provides nutrients to articular cartilage, and contains hyaluronic acid for shock absorption.

T

Tachycardia Health Conditions: An abnormally fast heart rate. In dogs, tachycardia is generally defined as a heart rate exceeding the normal range for the dog's size — above approximately 140-160 bpm for large dogs or 180-220 bpm for small dogs. Tachycardia can be a normal physiologic response or a sign of disease.
Taurine Nutrition & Supplements: A sulfur-containing amino acid critical for cardiac muscle function, retinal health, and bile acid conjugation. Taurine deficiency in dogs has been linked to dilated cardiomyopathy, particularly in breeds fed grain-free diets.
Telomere Longevity Science: Protective repetitive DNA sequences at chromosome ends that shorten with each cell division. Telomere attrition is a hallmark of aging; critically short telomeres trigger cellular senescence or apoptosis.
Thyroid Panel Testing & Diagnostics: A blood test measuring thyroid hormone levels (T4, free T4, TSH) used to diagnose hypothyroidism and hyperthyroidism. Thyroid dysfunction is one of the most common endocrine disorders in dogs, affecting metabolism, energy, and longevity.

U

Ultrasound Testing & Diagnostics: A non-invasive imaging technique using sound waves to visualize soft tissue structures in real time. Used for abdominal organ evaluation, cardiac assessment (echocardiography), and guided tissue sampling.
Urinalysis Testing & Diagnostics: Laboratory examination of urine measuring concentration, pH, protein, glucose, blood, and cellular contents. Essential for detecting urinary tract disease, kidney dysfunction, and diabetes.

V

Vaccination Treatments & Procedures: Administration of an antigen to stimulate adaptive immune protection against specific infectious diseases. Core vaccines protect against fatal diseases; non-core vaccines are risk-based. Titer testing can guide revaccination decisions.