Your vet hands you a printout covered in numbers, abbreviations, and reference ranges. ALT. BUN. CREA. ALKP. You nod like you understand. You do not. You fold it into your bag, drive home, and Google "dog blood work high ALT" at midnight while your dog sleeps peacefully on the couch. By 1 AM, you are convinced they have liver cancer. By 2 AM, you are crying. By 3 AM, you realize you have to be at work in five hours.
I have been on the other side of this conversation thousands of times. I hand over blood work results. I watch owners' faces shift from attentive to confused to quietly terrified. And I know that most of the panic is unnecessary. Blood work is a tool, not a verdict. And most "abnormal" results in dogs are not emergencies. They are signals. They are clues. They are not sentences.
The Chemistry Panel: What Each Value Actually Means
A standard chemistry panel checks about 15 to 20 values. Here are the ones that matter most, explained in plain English:
ALT (Alanine Aminotransferase) — This is a liver enzyme. When liver cells are damaged, ALT leaks into the blood. A mildly elevated ALT (say, 150 when normal is 10-100) can mean many things: recent medication, a fatty meal, mild dehydration, or early liver stress. A very high ALT (500+) is more concerning and usually warrants further testing. But here is the thing: ALT can be elevated without any actual liver disease. I see this constantly in dogs who have been on carprofen or other NSAIDs.
ALP (Alkaline Phosphatase) — Another liver enzyme, but also produced by bones. Elevated ALP is extremely common in older dogs. In many cases, it is benign — something called "idiopathic benign hepatic enlargement" that does not affect health or lifespan. However, very high ALP combined with other liver enzyme elevations can indicate Cushing's disease, liver disease, or certain medications.
BUN (Blood Urea Nitrogen) and CREA (Creatinine) — These are kidney values. BUN is influenced by hydration, diet, and protein intake. A high BUN with normal creatinine usually means dehydration, not kidney disease. When both are elevated, that is when we worry about kidney function. The ratio between them matters too.
| Value | What It Measures | Mild Elevation Often Means | High Elevation Warrants |
|---|---|---|---|
| ALT | Liver cell damage | Medication, mild stress | Ultrasound, bile acids |
| ALP | Liver/bone activity | Aging, benign enlargement | Cushing's testing, imaging |
| BUN | Kidney function + hydration | Dehydration, high protein diet | SDMA test, urinalysis |
| CREA | Kidney filtration | Muscle mass, dehydration | Full kidney workup |
| GLU | Blood glucose | Stress, recent meal | Fructosamine, insulin testing |
| TP/ALB | Protein levels | Dehydration, inflammation | Protein-losing disease workup |
The Complete Blood Count (CBC)
The CBC looks at red blood cells, white blood cells, and platelets. It tells us about infection, inflammation, anemia, and clotting ability.
HCT (Hematocrit) — The percentage of blood that is red blood cells. Low HCT means anemia. High HCT usually means dehydration. I see high HCT constantly in dogs who have not had water for a few hours before the blood draw. It is rarely meaningful.
WBC (White Blood Cell Count) — High WBC usually means infection or inflammation. Low WBC is more concerning — it can indicate bone marrow suppression, viral infection, or autoimmune disease. The differential (which types of white cells are high or low) matters more than the total number.
PLT (Platelets) — Low platelets can cause bleeding. Very low platelets (under 50,000) are an emergency. Mildly low platelets (100,000-150,000) are often a lab artifact — platelets clump together in some dogs and the machine undercounts them. We usually confirm with a blood smear.
The Values That Actually Worry Me
After 12 years in practice, there are a few patterns that make me sit up straight:
High BUN + High CREA + Low USG (urine specific gravity) — This is kidney disease until proven otherwise. The low USG means the kidneys are not concentrating urine properly. This combination is never benign.
Very High ALT + Very High ALP + Low ALB — This pattern suggests significant liver disease, possibly liver failure. Albumin is made by the liver. When it drops, the liver is struggling.
High Calcium — Elevated calcium in dogs is concerning until proven otherwise. The most common cause is a parathyroid tumor, but lymphoma and other cancers can also elevate calcium. I do not ignore high calcium.
Low Platelets + Low HCT — This suggests bleeding somewhere. Could be internal. Could be immune-mediated. Needs immediate investigation.
When to Panic and When to Wait
Here is my general rule: one mildly elevated value in an otherwise healthy dog is usually worth rechecking in 2 to 4 weeks, not panicking about tonight. Multiple elevated values, or one very high value, need more immediate attention. Context matters. A 15-year-old dog with mildly elevated kidney values and no symptoms is different from a 3-year-old dog with the same values and vomiting.
I also tell owners to ask their vet: "If this were your dog, what would you do next?" It is a simple question, but it cuts through the noise. Most vets will give you an honest, practical answer. If they seem dismissive or overly alarmed, a second opinion is reasonable.
Why do reference ranges vary between labs?
Each laboratory uses different equipment and calibration methods. A "normal" range at IDEXX might be slightly different from Antech. Your vet interprets results based on the lab that ran them. Do not compare values from different labs without accounting for this.
Should I get blood work done annually for my senior dog?
Yes. Absolutely. Annual blood work for dogs over seven catches problems early — before symptoms appear. Kidney disease, liver disease, diabetes, and thyroid disorders all show up on blood work weeks or months before the dog acts sick. Early detection means early intervention, which means better outcomes.
Can stress affect blood work results?
Yes. Stress elevates glucose, white blood cells, and sometimes liver enzymes. Dogs who are anxious at the vet often have slightly abnormal values that normalize when rechecked at home or after sedation. If your dog is a nervous wreck at the clinic, mention it. Your vet will factor it in.
I still remember the first time I had to tell an owner their dog's blood work was abnormal. I was a new grad, nervous, and I used too much medical jargon. The owner left in tears, convinced her 10-year-old Beagle was dying. In reality, the dog had mild dehydration and a slightly elevated ALT from a recent course of antibiotics. She was fine. I was not.
These days, I lead with reassurance. I explain what the numbers mean. I give context. And I always end with: "Blood work is a snapshot, not a story. We will recheck, we will monitor, and we will figure this out together." Because that is the truth. A single blood panel tells you where you are. It does not tell you where you are going.
Do you have your dog's most recent blood work sitting in a drawer somewhere? Pull it out. Look at it with fresh eyes. And if something does not make sense, call your vet. That is what they are there for.
