My dog ate raisins — how bad is it?

Quick answer

Raisins are concentrated grapes (about 4 g of grapes → 1 g of raisins after drying). The toxic compound is tartaric acid; the threshold scales with the concentration. Treatment is identical to grape exposure: induce vomiting if recent, activated charcoal, IV fluids for 48–72 hours, monitor kidney values.

Why raisins are 3–4× more concentrated than grapes

Drying grapes into raisins removes 75–80% of the water by mass — but the tartaric acid (the suspected nephrotoxic agent identified by Wegenast 2022) doesn't evaporate with the water, it concentrates. By weight, a raisin contains roughly four times the toxic load of an equivalent gram of fresh grape. A single 1.5 g raisin is biologically equivalent to about a 5 g grape.

That math has practical consequences. A 25 lb (11 kg) dog can hit the clinical-concern threshold with about 20 raisins (~30 g raisins ÷ 11 kg ≈ 2.7 g/kg) — a small handful, the kind a child might drop. The equivalent fresh-grape exposure would be ~120 g, roughly a full bunch. The same dog, same toxin, same risk — but the raisin scenario is visually less alarming, which is exactly why ASPCA APCC raisin calls often come from owners who didn't realize what was happening.

Hidden sources

Owners reliably spot a fresh-grape bowl on the counter. They miss raisins in everyday foods. The most common Pet Poison Helpline case logs include:

• Cereal — Raisin Bran is the obvious one (~7–8 raisins per ¼ cup), but many "fruit and fiber" granolas, museli mixes, and oat clusters contain raisins or sultanas in smaller amounts.
• Baked goods — oatmeal raisin cookies (5–10 raisins each), raisin bread / cinnamon raisin bagels (~15–25 raisins per slice), hot cross buns, rum cake, Christmas pudding, mince pies, bran muffins.
• Trail mix and granola bars — often raisin- or sultana-based, sometimes mixed with chocolate (compound exposure: see our chocolate toxicity calculator).
• Curries, tagines, and Persian rice dishes often use sultanas or currants as a savory-sweet element.

Currants (Zante currants — actually small dried grapes, not the unrelated berries) and sultanas (golden raisins) are biologically identical and pose identical risk.

First-aid window

Decontamination is most effective within the first 2 hours post-ingestion, when raisin material is still in the stomach. Standard protocol after a hotline triage call: induced vomiting (apomorphine if you can get to a vet quickly; 3% hydrogen peroxide at 1 mL/lb body weight, max 45 mL, under phone supervision if you can't), followed by activated charcoal to bind unabsorbed tartaric acid. After about 2 hours most of the relevant compound has moved into the small intestine where vomiting recovers little; the focus shifts to IV fluids to support glomerular filtration.

Per ASPCA APCC case data, dogs presented within 6 hours with prompt IV-fluid therapy have recovery rates above 90%. Once acute kidney injury is established (oliguria, rising creatinine 24–72 hours post-ingestion), mortality climbs sharply even with intensive care. Call the hotline before you go to bed — not the next morning.

Sources: ASPCA Animal Poison Control Center. Pet Poison Helpline. Eubig PA, et al. "Acute renal failure in dogs after the ingestion of grapes or raisins." J Vet Intern Med (2005). Wegenast CA et al. "Acute kidney injury in dogs following ingestion of cream of tartar and tamarinds." J Vet Intern Med (2022). Merck Veterinary Manual.