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Grapes toxic to dogs: kidney blood work and monitoring

Grapes, raisins, currants and sultanas can damage a dog’s kidneys. Most dogs that eat them stay well, but a few develop acute kidney injury, and nobody can predict which ones. Blood tests over the following days are how vets find out whether the kidneys are affected.

Written by the AI DiagAnimals editorial teamReviewed by the AI DiagAnimals TeamUpdated Our editorial policy

The essentials

There is no predictable toxic dose: a few grapes made one small dog ill, while other dogs ate much more without trouble. If your dog eats grapes or raisins, contact your vet or a pet poison center right away. Kidney values (creatinine and urea) are usually checked over about 72 hours. A high total calcium with a normal ionized calcium is a typical clue. Dogs seen early almost all do well; dogs already in kidney failure have a guarded outlook.

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Why grapes and raisins can harm dogs

The toxic part of grapes was unknown for many years. A strong recent hypothesis points to tartaric acid. In a poison-center case series, dogs that ate tamarinds or cream of tartar (both rich in tartaric acid) developed kidney injury with signs and lab results similar to grape poisoning [1]. In a laboratory study, tartaric acid damaged dog kidney cells but not human kidney cells, which may explain why dogs are sensitive [2]. This is still a hypothesis, not a proven mechanism [3].

There is no predictable toxic dose. In a Dutch study, four to five grapes caused kidney injury in a dachshund, while other dogs stayed well after eating up to 1 kg of raisins [4]. A 2024 review found the toxic dose difficult to establish and no clear difference between grapes, raisins, currants and sultanas [7].

Exposure is not only from the fruit bowl. In a Swiss series, 3 poisoned dogs had eaten grape marc, the pressed residue of wine-making spread on fields as fertilizer [5].

What to do and how long to watch

If your dog has eaten grapes or raisins, call your vet or a pet poison center right away, even if your dog seems fine. Do not try home remedies; your vet will decide what is needed.

Vomiting is usually the first sign. In grape-poisoned dogs, it started within 24 hours in 81% and within 48 hours in all of them [5]. Kidney markers can rise 24 to 48 hours after eating the fruit [4]. In the Dutch series, 14.7% of dogs developed any signs [4].

  • 72-hour window: the protocol described in the Dutch study monitored blood chemistry for 72 hours, with urea and creatinine measured daily for 3 days [4].
  • Late cases happen: in that study, the only dog that developed kidney injury first showed signs 3 days after eating the grapes [4].
  • Early markers: creatinine and urea are slow to detect an early fall in kidney function; the authors suggest SDMA may be more sensitive [4].

What the blood work shows

In 15 Swiss dogs with grape or raisin poisoning, all had acute kidney injury. Their values at admission were compared with dogs whose kidney injury had other causes [5]:

An annotated line from a lab report · Illustrative example
AbbreviationResultUnitLaboratory intervalFlag
CREA Creatinine6.8mg/dL0.5–1.7H
  1. Abbreviation CREA, CREAT or creatinine: the main kidney marker followed after grape ingestion [4].
  2. Result 6.8 mg/dL in this illustrative line: within IRIS acute kidney injury grade IV (5.1–10.0 mg/dL) [12].
  3. Unit mg/dL in the US; µmol/L elsewhere: 6.8 mg/dL ≈ 601 µmol/L (× 88.4).
  4. Laboratory interval An illustrative dog interval; each laboratory sets its own.
  5. Flag H: above the interval. After grapes, the trend over several days matters as much as one value [4, 12].

Unit converter

Equivalent values

  • Creatinine, µmol/L–
  • Creatinine, mg/L–

Conversion only changes the unit. Compare the result with the interval printed by the laboratory that measured it.

Medians at admission in referred dogs, all with severe kidney injury [5].
ValueGrape-poisoned dogs (median)Other kidney injury (median)
Creatinine12 mg/dL9.1 mg/dL
Total calcium13.2 mg/dL10.2 mg/dL
Ionized calcium1.3 mmol/L1.1 mmol/L
Phosphorus12.2 mg/dL13 mg/dL
Potassium6.2 mEq/L4.6 mEq/L

The authors call a high total calcium with a normal ionized calcium the most distinctive feature [5]. See high calcium in dogs and cats. In a larger US series of 43 dogs, a high calcium × phosphorus product, high phosphorus and high calcium were found in 95%, 90% and 62% of the dogs tested, and very high calcium was linked to a worse outcome [8]. Urea rises with creatinine; see BUN in dogs.

What the urine can show

  • Little or no urine: reported in 49% of grape-poisoned dogs, and linked to a worse outcome [5, 8].
  • Glucose in the urine with normal blood glucose: a general sign of damage to the kidney tubules [13]. Its exact frequency in grape cases is not known.
  • Granular or cellular casts: these always indicate kidney damage [14]. Glucose in the urine or granular casts are among the criteria used to define acute kidney injury [5].
  • What the tissue shows: damage to the first part of the kidney tubules was the most consistent finding in kidney tissue samples [6, 8].

A urinalysis is often run with the blood tests.

How kidney injury is graded

Vets use the IRIS grading of acute kidney injury, based on blood creatinine [12]:

Each grade is also classed by urine output and by the need for dialysis [12].
IRIS gradeBlood creatinine
IBelow 1.6 mg/dL (below 140 µmol/L), or a rise of 0.3 mg/dL or more within 48 hours
II1.7–2.5 mg/dL (141–220 µmol/L)
III2.6–5.0 mg/dL (221–439 µmol/L)
IV5.1–10.0 mg/dL (440–880 µmol/L)
VAbove 10.0 mg/dL (above 880 µmol/L)

IRIS notes that dogs in grades I–II may regain adequate kidney function within 2 to 5 days, while grades IV–V may die within 5 to 10 days without dialysis [12]. For long-term kidney disease, see kidney disease in dogs.

Outlook

The outlook depends mainly on when the dog is seen. Studies of dogs brought in early, most of which were decontaminated (treated early to remove the fruit), show very few kidney injuries. Studies of dogs already in kidney failure show much lower survival [4, 5, 8, 9, 10].

StudyDogsResult
Netherlands, 2022 [4]95 dogs followed after ingestionKidney injury in 1 dog (1%); all survived
UK emergency clinics, 2020 [10]606 dogsAll survived; 1 of 33 rechecked dogs reached IRIS grade I
US university hospitals, 2019 [9]139 dogsKidney injury in 8 of 120 (6.7%); 138 of 139 survived
UK emergency centres, 2026 [11]31,425 probable casesDeath rate 0.9%
US poison center, 2005 [8]43 dogs in kidney failure53% survived; 15 of 23 survivors fully recovered
Switzerland, 2020 [5]15 dogs, all IRIS grade IV–V8 survived (53%), all alive 9–13 months later

In the Swiss series, all 15 dogs were lethargic, vomiting, cold and producing little or no urine, and 11 had marked neurological signs that were reversible in survivors [5].

Related articles

Urinalysis for dogs and cats

Glucose, casts and urine concentration.

Read the article

Other foods and plants explained: xylitol, onion and garlic and, for cats, lilies.

En français : raisin et chien.

Questions to ask your veterinarian

  1. Should my dog’s kidney values be checked, and for how many days?
  2. What are the creatinine and urea today, and how do they compare with the first test?
  3. Is the calcium high, and has ionized calcium been measured?
  4. Is my dog producing a normal amount of urine?
  5. If there is kidney injury, which IRIS grade is it?
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Frequently asked questions

Will one grape hurt a 40 lb dog?

Nobody can say. There is no predictable toxic dose, and body size does not make it safe: four to five grapes caused kidney injury in a small dog, while other dogs ate far more without harm [4]. Call your vet or a poison center for advice.

What should I do if my dog eats a grape?

Contact your vet or a pet poison center right away, even if your dog seems well. Kidney values are often monitored for about 72 hours, because injury can appear after 24 to 48 hours or later [4].

Can raisins be poisonous to dogs?

Yes. Raisins, currants and sultanas are linked to the same kidney injury as fresh grapes, and a 2024 review found no clear difference in toxicity between them [7].

Which animals are grapes toxic to?

Most reports concern dogs. In a laboratory study, tartaric acid damaged dog kidney cells but not human kidney cells, a possible reason for the dog’s sensitivity [2].

Which blood tests show grape poisoning?

Creatinine and urea show the kidney injury. A high total calcium with a normal ionized calcium is a typical clue, and phosphorus and potassium are often high [5].

Sources

  1. Wegenast CA et al. Acute kidney injury in dogs following ingestion of cream of tartar and tamarinds and the connection to tartaric acid as the proposed toxic principle in grapes and raisins. J Vet Emerg Crit Care. 2022;32(6):812-816. doi.org/10.1111/vec.13234
  2. Coyne SR, Landry GM. Tartaric acid induces toxicity in Madin-Darby canine kidney cells, but not human kidney-2 cells in vitro. J Vet Emerg Crit Care. 2023;33(3):298-304. doi.org/10.1111/vec.13294
  3. Tancredi W, Bolduc S. Could oral calcium carbonate mitigate tartaric acid toxicity in dogs? A novel hypothesis. J Am Vet Med Assoc. 2025;263(12):1-2. doi.org/10.2460/javma.25.03.0160
  4. Dijkman MA et al. Incidence of Vitis fruit-induced clinical signs and acute kidney injury in dogs and cats. J Small Anim Pract. 2022;63(6):447-453. doi.org/10.1111/jsap.13483
  5. Schweighauser A et al. Toxicosis with grapes or raisins causing acute kidney injury and neurological signs in dogs. J Vet Intern Med. 2020;34(5):1957-1966. doi.org/10.1111/jvim.15884
  6. Morrow CMK et al. Canine renal pathology associated with grape or raisin ingestion: 10 cases. J Vet Diagn Invest. 2005;17(3):223-231. doi.org/10.1177/104063870501700302
  7. Downs J et al. Scoping review exploring the evidence base on Vitis vinifera toxicity in dogs after ingestion. Vet Rec. 2024;195(7):e4536. doi.org/10.1002/vetr.4536
  8. Eubig PA et al. Acute renal failure in dogs after the ingestion of grapes or raisins: a retrospective evaluation of 43 dogs (1992-2002). J Vet Intern Med. 2005;19(5):663-674. doi.org/10.1111/j.1939-1676.2005.tb02744.x
  9. Reich CF et al. Retrospective evaluation of the clinical course and outcome following grape or raisin ingestion in dogs (2005-2014): 139 cases. J Vet Emerg Crit Care. 2020;30(1):60-65. doi.org/10.1111/vec.12905
  10. Croft RS et al. Retrospective evaluation of Vitis vinifera ingestion in dogs presented to emergency clinics in the UK (2012-2016): 606 cases. J Vet Emerg Crit Care. 2021;31(1):74-79. doi.org/10.1111/vec.13025
  11. Altman et al. A multicenter, retrospective, cross-sectional analysis of fresh and processed Vitis (grape) ingestion in dogs and cats. Front Vet Sci. 2026;13:1812885. doi.org/10.3389/fvets.2026.1812885
  12. International Renal Interest Society (IRIS). Grading of Acute Kidney Injury. 2026. iris-kidney.com/s/IRIS-AKI-Grading_2026.pdf
  13. eClinPath, Cornell University College of Veterinary Medicine. Urine chemical constituents. eclinpath.com/urinalysis/chemical-constituents
  14. eClinPath, Cornell University College of Veterinary Medicine. Casts. eclinpath.com/urinalysis/casts

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.

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