Blood lead in dogs and cats
A blood lead test answers one question: has the animal taken in a meaningful amount of lead. Dogs and cats get it from old paint, dust from renovation and small lead objects. The number is read together with the signs, the blood smear and sometimes an X-ray — on its own it does not make the diagnosis.
What it shows
More than 90% of the lead circulating in the blood is bound to red blood cells, so the test is done on whole blood, not on serum. The tube is not spun, and a small volume is enough. Labs measure lead with instruments such as ICP mass spectrometry, so the test is usually sent to a specialised lab and the result comes back in days.
Lead in the blood shows exposure. Lead stored in the body can be released later, so signs may appear long after the original contact. Lead can also be measured in liver or kidney tissue.
Higher than reference — what it may be a sign of
- Lead exposure. A level above the threshold printed by the lab, together with suitable signs, supports lead poisoning. Typical signs of sudden poisoning are loss of appetite, behaviour changes, wobbliness, tremors and seizures. Longer exposure brings belly discomfort, vomiting, diarrhoea, lethargy, weight loss and anaemia.
- Common sources. Old house paint and paint chips, dust from sanding or renovating old houses, linoleum, fishing sinkers, lead shot, lead weights and solder. A chip of lead paint the size of a thumbnail can hold a lot of lead.
If poisoning is suspected — go to the vet right away, do not wait for the test.
Lower than reference
A low result is the expected one and speaks against recent meaningful exposure. Still, a test is a snapshot of the blood: lead hidden in the body can come out later, and the vet reads the number together with the signs, the smear and the history.
Look at together with
- Nucleated red blood cells — many of them (about 5–40 per 100 white cells) without severe anaemia suggest lead poisoning but do not prove it.
- Red cell morphology — basophilic stippling, small blue dots of RNA in red cells, can appear in lead poisoning even without anaemia, usually together with nucleated red cells and polychromasia. Stippling also occurs in strongly regenerative anaemia, so it is a clue, not a proof. It has nothing to do with the white cells called basophils.
- Hematocrit and MCV — anaemia from lead tends to have small, pale red cells in acute poisoning and normal-sized cells in long exposure.
- X-ray — can show lead objects in the stomach or gut.
Units and conversion
Blood lead is reported in µg/dL or µmol/L. One µmol/L is about 20.7 µg/dL, so 30 µg/dL is about 1.45 µmol/L. In the app each row keeps the unit printed on the form; the chart converts to µg/dL so forms from different labs line up.
Reference range
The reference value is on your lab’s form — for lead it is usually a threshold above which exposure is considered meaningful, not a range of healthy animals. The Merck Veterinary Manual says that blood lead above 30–35 µg/dL (0.30–0.35 ppm, about 1.45–1.7 µmol/L) indicates consequential exposure and that, with fitting signs, such levels support the diagnosis; 30 µg/dL can already go with clinical poisoning in dogs and cats. The final reading is the vet’s, together with the signs and other tests.
Cats and dogs
In cats, poisoning through grooming has been described: the cat licks off dust left by sanding lead-painted woodwork. Signs are similar to those in dogs, though an enlarged oesophagus (megaesophagus), seen in some poisoned animals, is rare in cats. The blood smear findings for lead are described for animals in general, not separately for cats.
Renovation of old houses is a common route of exposure in small animals, and swallowed objects such as sinkers or shot can be seen on an X-ray. In dogs the body gets rid of lead in several phases, and the slowest of them lasts thousands of days, which is why stored lead can keep coming back into the blood. Megaesophagus is among the possible signs of long exposure.
Add a lab form — Pet Tracker Space recognises the lines, keeps the form’s units and draws each indicator over time with your lab’s reference band.
Sources
- Wismer T. Lead Poisoning in Animals. Merck Veterinary Manual, professional version, full review June 2026.
- Texas A&M Veterinary Medical Diagnostic Laboratory. Lead (ICP/MS) — test and specimen requirements.
- eClinPath (Cornell University). Red blood cell inclusions — basophilic stippling.
- eClinPath (Cornell University). Nucleated red blood cells.
This page explains what a lab value means. It is not a diagnosis and not a substitute for your veterinarian — only they can interpret results for your pet.