What Blood Work Reveals About Your Pet’s Health

What Blood Work Reveals About Your Pet’s Health 🩸🐾

By Dr Duncan Houston

🔎 Quick Answer

Blood work helps your veterinarian assess red and white blood cells, platelets, organ function, hydration, inflammation, blood sugar, and electrolyte balance. It is one of the best ways to detect hidden illness early, monitor chronic disease, and make treatment or anaesthetic plans safer.

When a vet recommends blood work, it can sound like a routine extra.

It isn’t.

A small blood sample can reveal a huge amount about what is happening inside your pet’s body, often before obvious symptoms appear. That is why blood testing is so useful for wellness checks, senior pet screening, pre-anaesthetic safety, and investigating symptoms like vomiting, lethargy, weight loss, or drinking more than usual.

Your pet cannot tell us what feels off. Blood work helps fill in the blanks.

🩺 What “Blood Work” Usually Includes

In general, veterinary blood work has two main parts:

🧫 Complete Blood Count, or CBC

This looks at the cells in the blood.

🧪 Biochemistry, or Chemistry Panel

This looks at organ markers, proteins, electrolytes, and metabolism.

Together, these tests give your vet a much clearer picture of your pet’s internal health.

🔬 What a CBC Can Tell Us

A CBC focuses on the main blood cell types.

🔴 Red Blood Cells

These carry oxygen around the body.

If they are low, your pet may be anaemic. That can happen with:

• bleeding

• chronic disease

• immune-mediated disease

• parasites

• bone marrow problems

If they are high, it may suggest dehydration or, less commonly, certain disease processes.

⚪ White Blood Cells

These help fight infection and respond to inflammation.

If white cells are high, it may suggest:

• infection

• inflammation

• stress

• immune system activity

• some cancers

If they are low, your pet may be struggling to fight infection, or there may be an issue affecting the bone marrow or immune system.

🟣 Platelets

These help blood clot.

Low platelets can increase bleeding risk and may be seen with:

• immune-mediated disease

• tick-borne disease

• severe inflammation

• clotting disorders

A CBC is especially important before surgery, during illness, or when a pet seems weak, pale, bruised, or unwell.

🧪 What a Chemistry Panel Can Tell Us

This is where we get clues about organs, hydration, and metabolism.

🧠 Liver Values

Markers like ALT, ALP, AST, GGT, and bilirubin help us look at liver stress, liver cell damage, bile flow, and sometimes red blood cell breakdown.

Raised liver values do not always mean liver failure. They can also rise with:

• inflammation

• certain medications

• hormonal disease

• gallbladder issues

• secondary stress on the liver

They tell us to investigate further, not panic immediately.

💧 Kidney Values

Markers like urea, creatinine, and SDMA help assess kidney function.

These can rise with:

• dehydration

• kidney disease

• urinary obstruction

• reduced kidney perfusion

Kidney disease is one of the big reasons routine blood work matters, especially in older pets, because early kidney changes can be easy to miss at home.

🍭 Glucose

This is your pet’s blood sugar.

High glucose may be seen with:

• diabetes

• stress, especially in cats

• some hormonal diseases

Low glucose can be more urgent and may occur with:

• sepsis

• insulin overdose

• liver problems

• some tumours

• very young or tiny patients becoming unstable

🧂 Electrolytes

Sodium, potassium, chloride, and others help regulate nerve function, hydration, muscle activity, and heart rhythm.

Abnormal electrolytes can occur with:

• vomiting and diarrhoea

• Addison’s disease

• kidney disease

• urinary blockage

• severe dehydration

💪 Muscle and Tissue Markers

Values like CK can rise with muscle injury, prolonged struggling, trauma, seizures, or inflammation.

🥚 Protein Levels

Albumin, globulins, and total protein help assess hydration, inflammation, protein loss, liver function, and immune system activity.

Low proteins may suggest:

• gut loss

• kidney loss

• liver disease

• inflammation

High proteins may reflect dehydration or increased immune stimulation.

📊 Blood Work Does Not Give One Magic Answer

This is the important part.

Blood work is powerful, but it is not a fortune teller.

A single abnormal value does not always mean a major disease, and a normal result does not mean every possible problem has been ruled out. Blood results need to be interpreted alongside:

• the physical exam

• symptoms

• age

• breed

• medications

• imaging

• urine testing

• blood pressure

• history

Good vets do not just read numbers. We read the whole patient.

👵 Why Routine Blood Work Matters in Healthy Pets

A lot of owners assume blood tests are only needed when a pet is sick.

That is like waiting for your car engine to catch fire before checking the oil.

Routine screening can help catch:

• early kidney disease

• liver changes

• diabetes

• inflammation

• anaemia

• electrolyte problems

• thyroid disease, if paired with hormone testing

• changes before anaesthesia

Finding problems early often gives us more options and better outcomes.

📅 How Often Should Blood Work Be Done?

A sensible general guide is:

Healthy adult pets

Every 12 months, or as advised by your vet

Senior pets

Every 6 to 12 months

Pets with chronic illness

As often as needed for monitoring

Before anaesthesia or surgery

Whenever your vet recommends it

Older pets and pets on long-term medications often benefit from more frequent screening, because quiet changes can happen long before you see symptoms at home.

🧼 What Happens During the Test?

Usually, a small blood sample is collected from a vein in the leg or neck.

Most pets tolerate it very well. Some are a little dramatic about it, which, to be fair, is also how many humans behave around blood tests.

The sample may be run in-house for rapid results or sent to an external lab for a broader panel. Results may come back the same day or within a few days depending on the test.

🚨 When Blood Work Is Especially Important

Blood testing becomes particularly valuable when a pet has:

• vomiting or diarrhoea

• lethargy

• weight loss

• poor appetite

• increased thirst or urination

• pale gums

• jaundice

• seizures

• suspected toxin exposure

• chronic medication use

• a planned anaesthetic procedure

In these cases, blood work helps us make faster, safer, and more accurate decisions.

💬 Final Thoughts

Blood work is one of the most useful tools in veterinary medicine because it shows us what your pet cannot explain.

It can reveal anaemia, infection, inflammation, dehydration, kidney disease, liver stress, blood sugar issues, and so much more, often before symptoms become obvious. That makes it valuable not only when your pet is sick, but also when they seem perfectly fine.

A tiny sample can tell a very big story.

❓ FAQ

Does normal blood work mean my pet is completely healthy?

Not always. Blood work is a powerful screening tool, but it does not rule out every disease. It needs to be interpreted with the full clinical picture.

Why does my pet need blood work before surgery?

It helps identify hidden issues like anaemia, kidney disease, liver problems, or electrolyte changes that could affect anaesthetic safety.

Can blood work detect cancer?

Sometimes it can show changes that make cancer a concern, but it usually does not diagnose cancer on its own.

How often should senior pets have blood work?

Usually every 6 to 12 months, depending on age, health status, and any medications or chronic disease.

If you ever get lab results back and feel like you are staring at alphabet soup with anxiety on top, the ASK A VET™ app can help you understand what the numbers may mean and what questions to ask next.