FrançaisNormal calcium levels in dogs and cats
Blood calcium exists in three forms: bound to proteins (mostly albumin), bound to small molecules, and free or “ionized”. The ionized part is the one the body actually uses [1]. Most chemistry panels report total calcium (Ca or TCa); some laboratories and in-clinic analysers also measure ionized calcium (iCa) [2].
| Species | Total calcium (mg/dL) | Total calcium (mmol/L) |
|---|---|---|
| Dog | 9.1–11.7 | 2.3–2.9 |
| Cat | 8.7–11.7 | 2.2–2.9 |
How to read the calcium line
Here is an example line, followed by a converter for reports in other units.
- Abbreviation Ca, TCa or calcium. Ionized calcium appears as iCa or Ca²⁺.
- Result 13.4 mg/dL in this illustrative line, clearly above the interval.
- Unit mg/dL in the United States, mmol/L in Europe and mg/L on some French reports: 13.4 mg/dL ≈ 3.34 mmol/L.
- Laboratory interval The example uses the dog interval of the Merck Veterinary Manual [3].
- Flag H: above the interval. Your vet reads it with albumin and usually confirms it with ionized calcium [1, 2].
Unit converter
Equivalent values
- Calcium, mmol/L–
- Calcium, mg/L–
Conversion only changes the unit. Compare the result with the interval printed by the laboratory that measured it.
First step: is the calcium really high?
- Albumin. About 35–45% of total calcium is bound to proteins, mostly albumin. A high albumin, as in dehydration, can raise total calcium mildly without changing the active form; a low albumin can hide a true increase. Cornell does not recommend formulas that “correct” calcium for albumin [1].
- Ionized calcium. It is the more accurate test of the calcium the body actually uses. Serum is preferred; EDTA or citrate tubes cannot be used, and freezing or a sample left unseparated can shift the result [2].
- Age. Young, growing puppies can have calcium slightly above the adult interval [1].
- Kidney disease. In dogs and cats with chronic kidney disease, total calcium does not reliably predict ionized calcium, which can be low, normal or high [1].
Causes of high calcium in dogs
- Cancer-related hypercalcemia (humoral hypercalcemia of malignancy). The most common cause of persistent high calcium in dogs. T-cell lymphoma comes first, followed by anal sac adenocarcinoma; other carcinomas and thymoma are also described [1].
- Addison’s disease (hypoadrenocorticism). Up to 28–45% of affected dogs have a high total calcium [1]; in a UK study of 110 dogs, the prevalence was 34.5% [4]. It is checked with an ACTH stimulation test.
- Primary hyperparathyroidism. A parathyroid gland tumour or hyperplasia; inherited in Keeshonds [1].
- Vitamin D toxicity. Rodenticides containing cholecalciferol cause marked hypercalcemia within 24 hours, and dogs have been poisoned by chewing vitamin D–containing psoriasis creams [1].
- Other causes. Granulomatous fungal infections, and less often kidney disease [1].
Causes of high calcium in cats
High calcium is uncommon in cats. The most frequent causes are idiopathic hypercalcemia (no cause found despite testing, sometimes with calcium oxalate bladder or kidney stones) and cancer, more often carcinomas than lymphoma; kidney disease is a less frequent cause [1].
Idiopathic hypercalcemia is often managed first with a diet change and monitoring of ionized calcium [5].
Why high calcium matters
Calcium blunts the kidney’s response to the hormone that concentrates urine: affected animals often drink and urinate more, with a dilute urine. Persistent high calcium can damage the kidneys and cause mineral deposits in tissues. It also reduces muscle and nerve excitability, causing weakness, constipation and vomiting [1]. Signs depend on how high the calcium is and how fast it rose.
Tests your vet may suggest next
For the kidney values often read with calcium, see BUN in dogs and creatinine and BUN in cats. Albumin is explained in albumin and globulin in dogs. En français : le calcium chez le chien et le chat.
Lymphoma is a leading cause of high calcium in dogs: see lymphoma in dogs.
Questions to ask your veterinarian
- Is the calcium still high once albumin is considered, and should we measure ionized calcium?
- Was the sample handled in a way that could affect the result?
- Which causes do you want to rule out first, and with which tests?
- Are the kidneys affected? What do the urine concentration and phosphorus show?
- How soon should we repeat the test?
Get your pet’s chemistry panel explained, calcium included.
AI DiagAnimals reads calcium with albumin, phosphorus, the kidney values and your laboratory’s intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
What is a normal calcium level for a dog?
Roughly 9.1–11.7 mg/dL (2.3–2.9 mmol/L) for total calcium in the Merck Veterinary Manual table; your laboratory’s interval applies [3].
What are the most common causes of elevated calcium in dogs?
Cancer-related hypercalcemia, most often from lymphoma or an anal sac tumour, and Addison’s disease. Primary hyperparathyroidism and vitamin D poisoning are other causes [1].
What causes high calcium in cats?
Most often idiopathic hypercalcemia, where no cause is found, and cancer, usually carcinomas. Kidney disease is a less frequent cause [1].
Is a slightly high calcium always serious?
Not always. A mild increase can come from a high albumin or, in puppies, from growth. Ionized calcium tells whether the active calcium is truly raised [1, 2].
What are the symptoms of low calcium in dogs?
Muscle tremors, twitching, a stiff or wobbly gait, weakness and seizures. The most common cause of a low total calcium is simply a low albumin, which does not lower ionized calcium [1].
Sources
- eClinPath, Cornell University College of Veterinary Medicine. Calcium. eclinpath.com/chemistry/minerals/calcium
- eClinPath, Cornell University College of Veterinary Medicine. Ionized calcium. eclinpath.com/chemistry/minerals/ionized-calcium
- Merck Veterinary Manual. Serum biochemical analysis reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/serum-biochemical-analysis-reference-ranges
- Hall H et al. Prevalence of hypercalcemia in primary hypoadrenocorticism in dogs: multicenter, retrospective study. J Vet Intern Med. 2023;37(5):1685-1693. doi.org/10.1111/jvim.16786
- Rzeszutek U et al. Assessment of alendronate and dietary treatment in the management of feline idiopathic ionised hypercalcaemia and ionised hypercalcaemia associated with chronic kidney disease: 29 cases (2016-2022). J Small Anim Pract. 2024;65(9):682-693. doi.org/10.1111/jsap.13755
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.