The consumption of

grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began approximately 8,0 ...

s and

raisin A raisin is a Dried fruit, dried grape. Raisins are produced in many regions of the world and may be eaten raw or used in cooking, baking, and brewing. In the United Kingdom, Republic of Ireland, Ireland, New Zealand, Australia and South Afri ...

s presents a potential health threat to

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...

s. Their toxicity to dogs can cause the animal to develop

acute kidney injury Acute kidney injury (AKI), previously called acute renal failure (ARF), is a sudden decrease in renal function, kidney function that develops within seven days, as shown by an increase in serum creatinine or a decrease in urine output, or both. ...

(the sudden development of

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

failure) with

anuria Anuria is nonpassage of urine, in practice is defined as passage of less than 100 milliliters of urine in a day. Anuria is often caused by failure in the function of kidneys. It may also occur because of some severe obstruction like kidney stone ...

(a lack of urine production). The phenomenon was first identified by the Animal Poison Control Center (APCC), run by the

American Society for the Prevention of Cruelty to Animals The American Society for the Prevention of Cruelty to Animals (ASPCA) is a non-profit organization dedicated to preventing animal cruelty. Based in New York City since its inception in 1866, the organization's mission is "to provide effective mea ...

(ASPCA). Approximately 140 cases were seen by the APCC in the one year from April 2003 to April 2004, with 50 developing symptoms and seven dying. One theory of the mechanism of toxicity is the

tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes but also in tamarinds, bananas, avocados, and citrus. Its salt (chemistry), salt, potassium bitartrate, commonly known as cream of ta ...

tartrate A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. The formula of the tartrate dianion is O−OC-CH(OH)-CH(OH)-COO− or C4H4O62−. The main forms of tartrates used commercially are pure crystalline ...

content in grapes. This is based on the observation that dogs show similar symptoms and pathological findings after consuming

cream of tartar Potassium bitartrate, also known as potassium hydrogen tartrate, with formula K C4 H5 O6, is the potassium acid salt of tartaric acid (a carboxylic acid)—specifically, l-( + )-tartaric acid. Especially in cooking, it is also known as cream ...

tamarind Tamarind (''Tamarindus indica'') is a Legume, leguminous tree bearing edible fruit that is indigenous to tropical Africa and naturalized in Asia. The genus ''Tamarindus'' is monotypic taxon, monotypic, meaning that it contains only this spe ...

. It is not clear that the observed cases of kidney failure following ingestion are due to grapes only. Clinical findings suggest raisin and grape ingestion can be fatal, but the mechanism of toxicity is still considered unknown.

Pathology

The most common pathological finding is proximal renal tubular

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

. In some cases, an accumulation of an unidentified golden-brown pigment was found within renal epithelial cells.

Cause

The reason some dogs develop

kidney failure Kidney failure, also known as renal failure or end-stage renal disease (ESRD), is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney fa ...

following ingestion of grapes and raisins is not known as of 2015. Types of grapes involved include both seedless and seeded, store-bought and homegrown, and grape pressings from

wineries A winery is a building or property that produces wine, or a business involved in the cultivation and production of wine, such as a wine company. Some wine companies own many wineries. Besides wine making equipment, larger wineries may also feat ...

. A

mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξικός , "poisonous") is a toxic secondary metabolite produced by fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' is usually rese ...

is suspected to be involved, but none has been found in grapes or raisins ingested by affected dogs. (Requires registration.) The dose-response relationship has not been determined, but one study estimated 3 g/kg or greater for grapes or raisins. A 2024 review identified a relationship between grape ingestion and illness, though the specific type or quantity of grapes that cause toxicity remains unclear. Grape ingestion commonly leads to gastrointestinal and/or renal issues, with treatment depending on the symptoms; outcomes can vary. The author does not favor any particular explanation of toxicity but merely lists them.

Tartrate theory

An April 2021 letter to the editor of ''

JAVMA The American Veterinary Medical Association (AVMA) is an American not-for-profit association founded in 1863 that represents more than 105,000 veterinarians. The AVMA provides information resources, continuing education opportunities, publicat ...

'' hypothesized that the

in grapes could be the cause. This is because the authors saw two cases of cream of tartar ingestion, both with similar clinical findings, and the autopsied one with similar histological findings. A 2022 article expands on the letter with detailed reports of the 2 aforementioned cases of cream of tartar ingestion and 4 new cases of

ingestion. Again, clinical findings were similar. Tamarind is known to contain 8%–18% tartaric acid, much more than the up to 2% (typically 0.35%–1.1%) found in grapes. The authors believe that the assignment of tartaric acid as the culprit also explains the relative lack of incidents from dogs consuming commercial grape juice, jam, and wine, as these go through a process to remove tartrates. Precisely how tartrate can damage the dog kidney to cause proximal tubular necrosis is unclear.

Maleic acid Maleic acid or ''cis''-butenedioic acid is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Its chemical formula is HO2CCH=CHCO2H. Maleic acid is the ''cis'' Cis–trans isomerism, isomer of butenedioic acid, ...

causes a similar finding and is believed to selectively inhibit NaK-ATPase activity and/or deplete ATP in the proximal tubules. A 2023 study have observed tartaric acid toxicity in kidney cells of dogs, but not in human kidney cells. Blocking the OAT1 on the dog cells reduces this toxicity by preventing the cell from taking up tartaric acid. Transfecting the human version of

OAT4 Organic anion transporter 4 (OAT4) can refer to either of these carrier proteins: * Solute carrier family 22 member 9 (SLC22A9) * Solute carrier family 22 member 11 (SLC22A11) {{Short pages monitor