Senior Pet Bloodwork: What Your Vet Is Checking and Why It Matters

As pets age, routine veterinary visits start to look a little different. Instead of just vaccines and quick checkups, your veterinarian may begin recommending bloodwork every 6–12 months. Many pet owners agree to testing, but don’t fully understand what the veterinarian is actually looking for. Senior pet bloodwork isn’t just a random panel of numbers; it’s one of the most important tools for detecting disease early, monitoring aging organs, and helping pets live longer, more comfortable lives (Gunn and Alleman, 2005).

Here, we’ll break down what senior pet bloodwork includes, what each test evaluates, and why it matters so much for older dogs and cats.

When Is a Pet Considered a Senior?

Before discussing bloodwork, it helps to understand when pets are considered seniors.

In general:

• Small dogs: around 8–10 years

• Medium dogs: around 7–9 years

• Large dogs: around 6–8 years

• Cats: around 10 years

Senior pets age faster than humans, which means major health changes can occur in a short period of time. A problem that develops over a year in a pet might be similar to several years of aging in a human. That’s why routine bloodwork becomes so important in senior years. Routine bloodwork is crucial for maintaining your pet's health, supporting your pet's long term health, and improving your pet's quality of life as they age. Routine bloodwork also establishes baseline values unique to your individual pet, helping veterinarians detect subtle shifts before they become serious problems (Stockham and Scott, 2024).

Senior Pet Care and Monitoring

As pets age, they enter a new stage of life known as seniorhood, typically beginning around 7 years old for dogs and 9 years old for cats. During this time, senior pets require extra attention and specialized care to maintain their health and quality of life. Regular veterinary check-ups become even more important, with routine blood tests such as the complete blood count (CBC) and blood chemistry panels playing a key role in monitoring your senior pet’s health.

Senior pet care is all about early detection. Catching subtle changes can help identify problems before they become serious issues. By keeping an eye out for clinical signs and scheduling routine bloodwork, pet owners can help identify early signs of age-related diseases. This proactive approach allows for timely intervention, helping pets age gracefully and comfortably. Prioritizing senior pet care ensures that your beloved companion enjoys their golden years to the fullest.

What Is Senior Bloodwork?

Senior pet blood work, often referred to as senior bloodwork, typically includes two main components:

1. Complete Blood Count (CBC)

2. Blood Chemistry Panel

After this, another complimentary test on your pet's urine is:

1. Urianalysis

Depending on the clinical exam or the finding of the previous three tests, additional thyroid Testing and occasionally SDMA or other kidney markers may be requested to delve deeper into a potentially identified issue.

These comprehensive blood panels (also called senior blood panels) are designed to detect age-related health issues early and monitor changes over time. Veterinarians usually recommend a comprehensive senior wellness panel for senior pets.

These tests give veterinarians information about organ function, infection, anemia, hydration, overall metabolism, hormone balance, help identify or manage chronic disease and detect disease early before symptoms appear.

Many serious diseases in pets start silently, meaning your pet can look completely normal while changes are already happening internally. Pets have a tendency to compensate early in disease progression, making it hard to identify behaviors related to disease quickly.

Complete Blood Count (CBC)- Looking at the Blood Cells

The CBC is blood test that evaluates overall health by measuring red blood cells, white blood cells, and platelets. Red blood cells show how well oxygen is being carried and can indicate anemia, dehydration, or blood loss. White blood cells reflect the immune system and can signal infection, inflammation, immune disorders, or sometimes cancer. Platelets are responsible for blood clotting and help detect bleeding or clotting disorders, as well as some tick-borne diseases. Veterinarians commonly use a CBC to diagnose illness, monitor ongoing conditions, check health before surgery, and evaluate how a pet is responding to treatment (Stockham and Scott, 2024).

Red Blood Cells (RBCs)

Red blood cells carry oxygen throughout the body. If red blood cell levels are low, your pet may have anemia. Anemia in senior pets can be caused by chronic kidney disease, internal bleeding, cancer, chronic inflammation, autoimmune disease, parasites and bone marrow disease. Each of these conditions have different signs and symptoms, as well as other markers in the CBC or blood chemistry that will help narrow down the root cause. Your vet may order additional testing if they need to rule out or verify a potential diagnosis.

High red blood cell counts usually indicate dehydration but can also point to other rare diseases.

White Blood Cells (WBCs)

White blood cells are part of the immune system. They increase or decrease depending on what is happening in the body. High white blood cells may indicate infection, inflammation, stress, immune disease and leukemia or cancer.

Low white blood cells may indicate viral disease, bone marrow problems, severe infection or autoimmune disease.

Platelets

Platelets help blood clot. Low platelets can mean immune disease, tick-borne disease, bone marrow issues, certain cancers and internal bleeding risk.

The CBC is extremely important because it can reveal infection, inflammation, anemia, and some cancers.

Blood Chemistry Panel: Checking the Organs

The chemistry panel evaluates organ function and metabolism. The general chemistry panel blood work evaluates your pet's organ function, electrolyte balance, and blood sugar. These tests provide valuable insight into your pet's internal health and organ function, helping veterinarians detect issues such as kidney disease, liver disease, diabetes, and more (Jackson, 2013).

Below are the most common values and what they mean.

Kidney Values: BUN, Creatinine, SDMA

Kidney disease is one of the most common problems in senior pets, especially cats.

Kidney values, including blood urea nitrogen (BUN) and creatinine (CREA), will be abnormal if your pet's kidneys fail to filter toxins from the bloodstream effectively, which is a sign of kidney failure. As pets age, kidney efficiency naturally decreases, leading to slightly elevated BUN or creatinine levels that may not necessarily indicate disease (Srikala, 2020).

BUN (Blood Urea Nitrogen), Creatinine and SDMA: Evaluating the Kidneys

BUN measures waste products in the blood that should be removed by the kidneys.

High BUN can indicate kidney disease, dehydration, high protein diet and internal bleeding. The clinical exam and history before taking bloodwork further informs findings. Urianalysis can be useful for informing a dignosis as well.

Creatinine is another waste product filtered by the kidneys and is one of the most important kidney markers. High creatinine usually indicates kidney disease, dehydration, or possible urinary obstruction.

SDMA is a newer kidney test that can detect kidney disease earlier than creatinine.

Kidney disease often develops slowly and may not show symptoms until 70% of kidney function is already lost. Bloodwork helps detect kidney disease much earlier (Yerramilli et al., 2014).

Liver Values: ALT, AST, ALP, Bilirubin

The liver performs hundreds of functions, including detoxifying the body, producing proteins, and storing energy.

Elevated liver enzymes are common in senior pets, and liver enzyme fluctuations often occur as a normal part of aging. Liver enzymes like ALT and ALP commonly elevate modestly in older pets, often due to age-related changes rather than disease (Kozat & Sepehrizadeh, 2017).

ALT increases when liver cells are damaged.

High ALT may indicate liver disease, prescense of toxins, infection, inflammation, tumors and use of certain medications can also elevate it.

AST can increase with liver damage but also with muscle damage, so it must be interpreted with other values.

ALP increases liver disease, gallbladder disease, cushing’s disease, steroid medications or bone growth/bone disease.

Bilirubin increases when red blood cells break down or when the liver or gallbladder isn’t functioning properly. High bilirubin may indicate liver disease, gallbladder disease, bile duct obstruction or red blood cell destruction (Stockham and Scott, 2024).

Blood Sugar (Glucose)

Glucose levels help detect diabetes and other metabolic issues.

High glucose may indicate:

• Diabetes

• Stress (especially in cats)

• Pancreatitis

• Cushing’s disease

Low glucose may indicate:

• Insulin overdose

• Severe infection

• Liver disease

• Certain tumors

Diabetes is common in senior pets, especially overweight cats and dogs.

Proteins: Albumin and Globulin

These values help evaluate liver function, kidney disease, nutrition, and chronic inflammation.

Low albumin may indicate liver disease, kidney disease, protein loss through intestines, malnutrition or chronic disease.

High globulin may indicate chronic inflammation, infection, immune disease or cancer.

The ratio between albumin and globulin can give veterinarians clues about chronic disease and immune system problems.

Electrolytes: Sodium, Potassium, Chloride

Electrolytes are critical for nerve function, muscle contraction, hydration, and heart function.

Abnormal electrolytes can indicate kidney disease, dehydration, Addison’s disease, urinary blockage, severe illness and vomiting or diarrhea can also alter these. Potassium is especially important in older cats with kidney disease.

Thyroid Testing

Thyroid disease is very common in senior pets. The thyroid gland regulates metabolic rate and blood calcium levels, making it a key part of your pet’s endocrine system. Thyroid testing helps assess the function of this important organ.

Cats: Hyperthyroidism

Older cats commonly develop hyperthyroidism, where the thyroid becomes overactive.

Symptoms include:

• Weight loss

• Increased appetite

• Hyperactivity

• Vomiting

• Increased thirst

• Fast heart rate

Bloodwork checks T4 levels to diagnose this condition.

Dogs: Hypothyroidism

Dogs more commonly develop hypothyroidism, where the thyroid is underactive.

Symptoms include:

• Weight gain

• Low energy

• Hair loss

• Skin infections

• Cold intolerance

Thyroid testing helps diagnose this condition.

Both species can present with hyper or hypothyroidism. These are just the most common for each species.

Understanding Reference Ranges

Reference ranges (usually in a column next to your pet's result) are the standard values used to interpret blood test results in senior pets. These ranges represent what is considered normal for healthy animals, but they don’t always account for the natural changes that occur as pets age. Veterinarians take into account your pet’s age, breed, clinical exam and medical history when reviewing bloodwork, as what’s normal for a young adult may not be the same for a senior pet (Jackson, 2013).

One of the most valuable aspects of routine bloodwork is tracking trends over time. Even if your senior pet’s kidney values or liver enzymes are within the reference range, gradual changes can signal the early stages of kidney disease, liver disease, or other chronic conditions. Sometimes months or years before clinical signs appear, these values can start changing. By understanding the limitations of reference ranges and focusing on these trends, veterinarians and pet owners can make informed decisions about senior pet care, including when to adjust treatment plans or take preventive action (Stockham and Scott, 2024). Early medical intervention based on these subtle changes can make a significant difference in your pet’s long-term health and quality of life.

Chronic Conditions Management

Chronic conditions such as kidney disease, liver disease, and thyroid disease are common in senior pets, and managing them requires a proactive and ongoing approach. Routine bloodwork (including complete blood count (CBC), blood chemistry panels, and thyroid hormone testing) allows veterinarians to monitor kidney values, liver enzymes, and other important markers. This regular monitoring helps detect early signs of disease progression, enabling timely intervention and adjustments to treatment plans.

For senior pets living with chronic illness, more frequent testing may be necessary, as their health status can change rapidly. Imaging tests, pathology and additional diagnostics may also be recommended to get a complete picture of your pet’s internal health. By working closely with your veterinary team and staying on top of routine wellness testing, pet owners can help manage chronic conditions effectively, slow disease progression, and provide the best possible preventive care (Rizzi, 2015). Early intervention and frequent testing are key to maintaining your senior pet’s comfort, happiness, and overall quality of life.

Why Senior Bloodwork Is So Important

Many pet owners wait until their pet is sick to do bloodwork, but by then disease may already be advanced.

Senior bloodwork helps early detection of:

• kidney disease

• liver disease

• diabetes

• thyroid gland issues

It can also identify signs of:

• anemia

• infection

• inflammation

• some cancers

Additionally, routine bloodwork can:

• monitor medication and their toll on the body

• Establish baseline values

• Track changes over time

Tracking trends over time in your pet's bloodwork is more valuable than single test results, as it helps protect your pet's long term health and quality of life (Rizzi, 2015). Blood test results also guide personalized health plans for senior pets, including dietary modifications and supplement recommendations, supporting your pet's health and overall well being (Schooley et al., 2024).

One of the most important uses of senior bloodwork is creating a baseline. If your pet has normal bloodwork at age 8, then at age 10 the veterinarian can compare results and see subtle changes that might indicate early disease (Srikala, 2020).

How Often Should Senior Pets Have Bloodwork?

Most veterinarians recommend:

• Healthy senior pets: every 12 months

• Senior pets with medical conditions: every 6 months

• Pets on medications: every 3–6 months

• Very old pets (14+): every 6 months

Geriatric pets (age 10+) often require bi-annual testing as the risk for organ dysfunction increases. Pets managing illnesses or taking long-term medications may need testing every 3 to 4 months to monitor stability and adjust dosages. Veterinarians typically recommend baseline testing at age seven, followed by annual or twice a year screenings depending on health status, especially for older dogs and senior dogs. Most veterinarians recommend annual bloodwork for healthy senior pets aged 7-10 years.

Because pets age faster than humans, yearly bloodwork is similar to a human getting bloodwork every few years.

Signs Your Senior Pet Needs Bloodwork Sooner

You should schedule bloodwork if you notice:

• Drinking more water

• Urinating more

• Weight loss

• Weight gain

• Decreased appetite

• Vomiting

• Diarrhea

• Lethargy

• Weakness

• Bad breath

• Behavior changes

• Confusion

• Hair loss

• Panting

• Accidents in the house

• Trouble walking

• Pale gums

• Seizures

These are clinical symptoms that may indicate underlying disease (Srikala, 2020). However, many illnesses can develop gradually, often without obvious symptoms until they reach an advanced stage, making early detection through blood tests essential. These signs often indicate internal disease that bloodwork can help diagnose.

The Biggest Benefit: Early Detection

The biggest reason veterinarians recommend senior bloodwork is early detection.

Regular bloodwork is essential for monitoring your senior pet's health, tracking how well chronic illnesses are being managed, and ensuring treatment plans remain effective. Bloodwork can also reveal how your pet's body is responding to medications, ensuring they are not negatively impacting organ function.

Early detection can:

• Slow kidney disease progression

• Manage diabetes earlier

• Treat thyroid disease sooner

• Detect liver disease earlier

• Catch infections sooner

• Detect some cancers earlier

• Improve quality of life

• Extend lifespan

Many diseases that are fatal when caught late are manageable when caught early. Quality of life can be extended when diseases are caught early as treatments and lifestyle changes can slow disease progression. Many of the diseases mentioned do not have a cure, but when managed appropriately can give your pets many extra months or years by your side. When an owner is well informed on their pet's potential or current illnesses, the pet has a better quality of life (Gunn and Alleman, 2005).

Senior bloodwork often finds problems months or even years before symptoms appear.

Things to keep in mind

Senior pet bloodwork is not just a routine test, it is one of the most important tools in preventive veterinary medicine. These tests allow veterinarians to look inside the body, evaluate organ function, detect disease early, and monitor aging changes before they become serious problems.

When your veterinarian recommends senior bloodwork, they are not just running random tests. They are evaluating your pet’s kidneys, liver, blood cells, thyroid, metabolism, hydration, and overall health. They are looking for early signs of disease, changes from previous years, and anything that could affect your pet’s quality of life.

The goal of senior bloodwork is simple: help pets live longer, healthier, more comfortable lives. At the end of the day, this is what we all want, more quality time with out pets by our side.

If you have a senior pet, routine bloodwork is one of the best things you can do to protect their health. Many owners say they want their pets to live as long as possible,but the real goal should be for them to live as long as possible and feel good during those years. Senior bloodwork helps make that possible.

Practical tips for senior pet bloodwork

Veterinary technicians will collect small blood samples, usually from a leg or neck. Most veterinarians recommend a 12-hour fast before bloodwork to ensure accurate glucose and lipid measurements, but water should always remain available during this time. Keeping your pet calm during transport and at the clinic can help reduce stress and improve test accuracy. Scheduling morning appointments can make fasting easier for your pet. Always ask your veterinarian whether to give morning medications before testing.

References

Gunn, R. G., & Alleman, A. R. (2005). Clinical pathology in veterinary geriatrics. Veterinary Clinics: Small Animal Practice, 35(3), 537-556.

Jackson, M. L. (2013). Veterinary clinical pathology: an introduction. John Wiley & Sons.

Kozat, S., & Sepehrizadeh, E. (2017). Methods of diagnosing in liver diseases for dog and cats. Turkish Journal of Scientific Reviews, 10(2), 36-46.

Rizzi, T. (2015). Blood testing in the geriatric dog. Vet Focus, 25(1), 31-7.

Schooley, E., Hegarty, E., & Michael, H. (2024). Frequency of Laboratory Abnormalities in Dogs and Cats Presenting to Veterinary Clinics in the United States for Wellness Visits. Available at SSRN 5010477.

SRIKALA, D. (2020). DIAGNOSTIC AND MANAGEMENTAL ASPECTS OF CERTAIN GERIATRIC DISEASES IN DOGS.

Stockham, S. L., & Scott, M. A. (Eds.). (2024). Fundamentals of veterinary clinical pathology. John Wiley & Sons.

Yerramilli, M., Obare, E., Jewell, D. E., & Hall, J. A. (2014). SYMMETRIC DIMETHYLARGININE (SDMA) INCREASES EARLIER THAN SERUM CREATININE IN DOGS WITH CHRONIC KIDNEY DISEASE (CKD).: NU-42. Journal of Veterinary Internal Medicine, 28(3), 1084-1085.