Grapes and Raisins

Chapter 46 Grapes and Raisins



Michelle S. Mostrom, DVM, MS, PhD





• Raisins and grapes may be toxic to some dogs—-no apparent dose response exists between the exposure dose and development of renal disease.

• Clinical signs of toxicosis include vomiting, anorexia, diarrhea, lethargy, abdominal pain, oliguria, and subsequent anuria.

• Clinical pathological changes are of acute renal failure and include elevated blood urea nitrogen and creatinine concentrations, along with hypercalcemia and hyperphosphatemia.

• Treatment includes gastrointestinal decontamination and aggressive fluid therapy for up to 72 hours postingestion. Prognosis for animals with clinical oliguria or anuria is poor and requires prolonged aggressive supportive care (e.g., hemodialysis, peritoneal dialysis).

• Histopathological changes observed in the kidney include proximal renal tubule degeneration and/or necrosis (with intact basement membranes) and tubular debris or proteinaceous casts in the tubules and collecting ducts. Intracellular and intraluminal pigment has been observed in some cases.


SOURCES


A grape is the fruit of a vine of the genus Vitis. Raisins are dried grapes, and grapes do not become raisins until their moisture content is reduced to about 15%. Raisin colors can vary as a result of the different drying processes; a dark purple or black raisin is sun-dried, a light brown raisin is mechanically dehydrated, and yellow raisins are mechanically dried and treated with sulfur dioxide. Grapes and raisins have been reported to cause poisoning in dogs since the mid-to-late 1990s. No clear confirmed cases of raisin and grape toxicosis have been described in cats, although there have been anecdotal reports suggesting cats may be susceptible as well. The toxic syndrome is observed with consumption of varying amounts of fresh grapes (all types and colors) from stores or private yards, grape crushings, fermented grapes from wineries, and commercially available raisins.1



TOXIC DOSE


The estimated quantity of raisins or grapes causing toxicity ranges between 0.41 to 1.1 oz/kg (11 to 31 g/kg, up to 57 g/kg).1,2 An estimated dry weight toxic dose is 0.1 to 1 oz/kg of body weight (2.8 to 28 g/kg).3,4 Other reports have calculated toxic, and potentially fatal, doses as ranging from 0.16 to 0.7 oz raisins, as is, per kg of body weight; and 4 to 5 grapes, as is, was toxic to an 8.2-kg dog.5



TOXICOKINECTICS


The toxic principle(s) has not been identified. Ochratoxin, flavonoids, tannins, polyphenolics, and monosaccharides have all been hypothesized as potential toxic principles; to date, none have been proven. Toxicities generally have a fairly rapid onset of clinical signs and probable excretion of a toxin through the kidneys. There does not appear to be a dose-response relationship between the amounts of grapes and raisins ingested and the resultant renal lesions, implying some variation in the amount of toxic principle(s) and/or varying sensitivities in individual dogs.3



MECHANISM OF TOXICITY


The mechanism of toxicity is not known at this time. It would appear to involve a nephrotoxic agent or idiosyncratic reaction leading to hypovolemic shock and renal ischemia.5

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Sep 11, 2016 | Posted by in SMALL ANIMAL | Comments Off on Grapes and Raisins

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