Vet's Corner - Beware the deadly raisin!

Information has come to light recently regarding the toxic effects of raisins, sultanas and grapes on dogs.  The Veterinary Poisons Information Service (VPIS), the agency who provides information and advice to Veterinary Surgeons in cases of toxicity, has provided the following information.  The agency first became aware of this problem a few years ago after a spate of cases in close succession.  A check through their database revealed many serious cases in the past.

Then the treating veterinarians had assumed that the raisins could not be the cause of the toxicity, but now there is a growing body of evidence that the fruits are much more toxic than expected, specifically to dogs.  The UK experience is consistent with the findings of the equivalent of the VPIS in the USA.

In the UK in 2004 four out of 41 reported cases had a fatal outcome (1 death and 3 euthanized).  The toxic/fatal dose can be as little as 14g (1/2 oz) per kg bodyweight, though it can range from 14g (1/2 oz) to 57g (2 and 1/3 oz) per kg bodyweight.  An American paper quotes a range between 11.5g (1/3oz) to 31g (1 and 1/3oz) per kg bodyweight as a fatal dose.  These ranges apply to all grape derived products, including chocolate covered raisins.  These carry the additional danger of chocolate poisoning.  However, milk chocolate is more likely to produce gastrointestinal upsets than poisoning, due to the very low cocoa content and high fat content.  Dark chocolate (high cocoa content) covered raisins, if ingested in large quantity, could in addition to the clinical signs indicated below, produce signs consistent with chocolate poisoning.

The clinical signs of raisins poisoning are usually observed within 6 hours, with vomiting, diarrhoea, anorexia, lethargy and abdominal tenderness.  Partly digested grapes or raisins may be seen in the vomit or faeces.  The effects on the kidneys (renal impairment) become evident normally from 24hours after ingestion.  Dogs may pass little or no urine and in these cases the prognosis is very poor.  Some appear dehydrated and some drink in excess (polydipsia).

Treatment normally consists of gastric decontamination for recent ingestions (less than 2-3 hours), inducing vomiting and administering activated charcoal to prevent further absorption; using anti-emetics if vomiting persists; and providing aggressive intravenous fluid therapy foe at least 48 hours for rehydration and support of renal function.  Additional medication may be used as necessary to re-establish urine output and aid renal perfusion.  Renal function and electrolytes should be monitored for 72hrs post ingestion.

Should your dog eat raisins or any grape derived product, contact your veterinary surgeon as soon as possible and ideally try to work out how much he or she may have ingested.  Store all these products in jars or sealed containers rather than in the original bags, but keep a record of the bag size in case your dog has an above average talent for stealing.  Spins in particular can be very clever thieves!

Cristiana Hill, Veterinary Advisor to the ISCGB
This email address is being protected from spambots. You need JavaScript enabled to view it.

(With grateful thanks to the VPIS for providing the above information)