Folate in cats and dogs

What it shows

Folate is absorbed mainly in the jejunum, the proximal part of the small intestine, while cobalamin is absorbed at the far end, in the ileum. That is why the two are measured together: their combination hints at which part of the small intestine is affected. Gut bacteria produce folate, so when there are too many of them in the small intestine (dysbiosis), the blood level can go up.

The result also depends on how severe, how widespread and how long-standing the problem in the intestinal lining is, and on what the animal eats. So a folate inside the range does not exclude intestinal disease, and a value outside it is a clue, not a diagnosis.

Higher than reference — what it may be a sign of

• Small intestinal dysbiosis — it usually develops secondary to chronic enteropathy or other gut disorders and can come together with a low B12. In dogs, high folate is also described with exocrine pancreatic insufficiency (EPI), linked to bacterial overgrowth.
• Recent folic acid supplements — they can raise the value too, so the vet needs to know about them.
• Hemolysis in the sample — red blood cells contain more folate than serum, so a hemolysed sample gives a falsely high result.

Lower than reference

A low folate is consistent with disease of the proximal small intestine. If cobalamin is low as well, the problem may be spread along the small intestine (a diffuse enteropathy). Not every intestinal disease lowers folate: some are not severe or long-standing enough to change it.

Folate in serum is not very stable at room temperature, which is why the sample travels to the laboratory cooled and protected from light.

Look at together with

• Cobalamin (B12) — the main partner. Low folate with normal B12 — the beginning of the small intestine; both low — disease along its length; high folate with low B12 — possible dysbiosis.
• TLI — rules exocrine pancreatic insufficiency in or out; in EPI, dysbiosis and changes in B12 and folate are common.
• Pancreatic lipase (cPL, fPL) — part of the same work-up of chronic gut signs, but it looks for pancreatitis.
• The hemolysis note on the form — if the lab flags hemolysis, a high folate from that sample is read with caution.

Units and conversion

Folate is reported in µg/L or ng/mL — the same number, because 1 ng/mL equals 1 µg/L — and some labs use nmol/L. 1 nmol/L is about 0.441 µg/L, so 20 nmol/L is about 8.8 µg/L, and 10 µg/L is about 22.7 nmol/L. In the app each row keeps the unit printed on the form; the chart converts to one unit so forms from different labs line up.

Reference range

The reference range is on your lab’s form, and dogs and cats have separate intervals. For a reliable result the sample is serum without hemolysis, taken after 8–12 hours without food, protected from light and kept cool on the way to the laboratory; some laboratories do not accept EDTA plasma for this test. Because folate and cobalamin are read as a pair, the vet usually compares where each of them sits in its own interval rather than looking at a single number.

Cats and dogs

Sources

1. Texas A&M Gastrointestinal Laboratory — Serum Cobalamin (Vitamin B12) and Folate (Vitamin B9)
2. Texas A&M Gastrointestinal Laboratory — Frequently Asked Questions
3. Malabsorption Syndromes in Small Animals. Merck Veterinary Manual
4. Cornell University Animal Health Diagnostic Center — Canine, Feline and Equine Metabolic Function Tests
5. VCA Animal Hospitals — Testing for Pancreatic Disease
6. VCA Animal Hospitals — Malabsorption and Bacterial Overgrowth in Dogs
7. IDEXX — Clinical Approach to Chronic GI Disease in the Feline Patient