Gastrin in cats and dogs

What it shows

Gastrin is a gut hormone (neuropeptide) that stimulates the secretion of gastric acid. A gastrinoma is a neuroendocrine tumour, usually of the pancreas, that makes gastrin without control. Excess gastrin means excess acid, which leads to ulcers in the stomach and duodenum and to chronic vomiting. The combination of such a tumour, high gastrin and gut ulceration is called Zollinger-Ellison syndrome.

Gastrinomas are rare — less frequent than insulinomas — but have been reported in dogs and cats. Signs are often vague: poor appetite, vomiting of blood, intermittent diarrhoea, weight loss and black, tarry stools.

Gastrin measurement is nonspecific: it supports a gastrinoma diagnosis but is not used as the only criterion. Endoscopy often shows ulcers in the stomach or duodenum, and exploratory surgery may ultimately be needed for a definitive diagnosis.

Higher than reference — what it may be a sign of

• Gastrinoma — the reason the test exists. Values far above the upper limit are expected; see the thresholds below.
• Acid-reducing medicines of the proton pump inhibitor group — even short-term use causes large increases in gastrin, in dogs and in cats. In cats this is the only reported cause of high gastrin other than a gastrinoma. The vet takes recent medicines into account when reading the result.
• Kidney disease (dogs) — is listed among the causes of high gastrin.
• Other conditions in dogs: obstruction of the stomach outlet, removal of part of the small intestine, gastric dilatation-volvulus, and immunoproliferative enteropathy of Basenjis.

Lower than reference

Reference intervals for gastrin are often given only as an upper limit, so a low value has no clinical meaning of its own. The question the test answers is whether gastrin is high, and how high.

Look at together with

• Creatinine and SDMA — kidney disease raises gastrin in dogs, so kidney values help explain a moderate rise.
• Urea (BUN) — can rise with bleeding into the gut, a possible consequence of ulcers.
• Hematocrit — blood loss from ulcers (vomited blood, black stools) can show up as anaemia.

Units and conversion

Gastrin is reported in ng/L or pg/mL. These are the same number: 1 pg/mL equals 1 ng/L, so 100 pg/mL is 100 ng/L. In the app each row keeps the unit printed on the form; the chart puts both on one scale without changing the number.

Reference range

The reference range is on your lab’s form. Intervals differ between laboratories and assays: one specialist laboratory gives less than 28 ng/L for dogs and less than 40 ng/L for cats, while a reference interval of 15.1–78.9 ng/L has been published for healthy dogs after 12 hours without food. For a suspected gastrinoma the Texas A&M Gastrointestinal Laboratory suggests, until a more precise cut-off is established, a threshold of ten times the upper limit — above 280 ng/L in dogs and above 400 ng/L in cats. It calls this threshold likely conservative: in cats a smaller rise may already suggest a gastrinoma once other causes, especially acid-reducing medicines, have been carefully ruled out.

Cats and dogs

Sources

1. Texas A&M Gastrointestinal Laboratory — Gastrin.
2. Buishand F. Islet Cell Tumors in Dogs and Cats. Merck Veterinary Manual, professional version, full review May 2024.
3. Britton B. Gastrointestinal Paraneoplastic Syndromes in Small Animals. Merck Veterinary Manual, professional version, full review September 2025.