Factors influencing outcome of Vitis vinifera (grapes, raisins, currants and sultanas) intoxication in dogs

Abstract

INGESTION of the fruits of Vitis vinifera (grapes, raisins, currants and sultanas) causes acute renal failure in dogs. The mechanism of toxicity is currently unknown, although hypotheses include tannin intolerance in dogs (Singleton 2001), the contamination of the fruits with mycotoxins, pesticides or heavy metals (Gwaltney-Brant and others 2001), sugar overload leading to shock (Singleton 2001), idiosyncratic reactions due to enzymatic differences (Mazzaferro and others 2004) or ingestion of excess vitamin D (Gwaltney-Brant and others 2001). The quantity of fruit that is harmful to dogs is also unknown. This short communication describes factors that influenced the clinical course and outcome of 169 cases of Vitis intoxication in dogs reported to the Veterinary Poisons Information Service (VPIS), London. The VPIS is a 24-hour emergency telephone service that advises veterinary professionals in the UK on the management of actual or suspected animal poisonings. For each inquiry, details of the exposure and the clinical history are recorded on the VPIS database. Postal questionnaires are sent to approximately 55 per cent of inquirers to gather additional information and data on the outcome. One hundred and eighty reports of ingestion of Vitis fruits by dogs were identified in the VPIS database, recorded between August 1994 and September 2007. A variety of fruits had been ingested, including raisins (69 cases), grapes (four cases involving red grapes, three including white grapes and 56 of unknown type), sultanas (21 cases), currants (one case) and unspecified or mixed dried fruits (23 cases). The fruits were ingested raw or in the form of fruit cakes, mince pies, chocolate bars, malt loaf, scones and snack bars. The quantities ingested varied from two grapes to 2 kg of grapes. Of the 180 cases, the outcome was unknown in 11 cases, 101 dogs remained asymptomatic and 68 developed clinical signs. Of the 68 clinically affected dogs, 50 made a full recovery, one had ongoing effects at the time of follow-up, 13 died and four were euthanased; two of these were euthanased for reasons other than grape toxicity, and they were excluded from further analysis. Common clinical effects included vomiting, diarrhoea, lethargy, depression and acute renal failure. Signs of renal insufficiency or failure (oliguria, anuria, polydipsia, proteinuria, elevated serum concentrations of creatinine and urea) occurred in four of the 50 dogs that subsequently made a full recovery and 13 of the 15 dogs that died or

Grapes and Raisins

“…4 Other treatments to combat potential renal failure may include furosemide, dopamine, mannitol, furosemide, H 2 -antagonists, and hemodialysis or peritoneal dialysis. 1,4 Prognosis Clinical signs of ataxia, weakness, and oliguric or anuric renal failure in dogs indicate a poor prognosis. Aggressive fluid therapy or hemodialysis and peritoneal dialysis may be inadequate to overcome the anuria at this stage.…”

“…1 The estimated quantity • Raisins, grapes, sultanas, and currants 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.…”

“…Within 24 hours to several days postingestion, dogs may appear dull and dehydrated with oliguria or anuria, with or without isosthenuria. [1][2][3] The onset of azotemia is not known in many cases because of a lack of recognition of the problem by the owners and subsequent delayed referral to a veterinary facility. The acute renal failure may progress to severe metabolic abnormalities and anuria, resulting in death or euthanasia as a result of poor treatment response.…”

Natural Occurrence of Grape Poisoning in Two Dogs

“…Canine grape poisoning has been reported in America in 2001 [5] and Europe in 2003 [7]. Several reports have described acute renal failure after grape or raisin ingestion independent of age, sex, or breed [2,3,10]. There were no differences in toxicity by grape color or type (raw, raisin, sultana, currant, fermented, crushed) [9,10].…”

“…Several reports have described acute renal failure after grape or raisin ingestion independent of age, sex, or breed [2,3,10]. There were no differences in toxicity by grape color or type (raw, raisin, sultana, currant, fermented, crushed) [9,10]. The toxic mechanisms of grape toxicity are still unclear [1]; however, nephrotoxins, tannins, pesticides, heavy metals, glucose overload, excess vitamin D, hypovolemic shock, and renal ischemia are all potential causes [7].…”