Another potential Christmas food hazard are grapes and their dried fruits (sultanas, raisins and currants). This includes Christmas pudding, Christmas cake and mince pies. Ingestion of grapes or their dried fruits can cause renal failure in dogs but this only happens in a minority of cases. Not all dogs are affected and the reason for this remains unknown. There is also no apparent dose-response relationship.
We have follow up information on over 1000 cases of grape and dried fruit ingestion in dogs but only a small number died or were euthanased. Until recently we had had no fatal cases reported since 2013.This could be for a number of reasons including increased awareness among both veterinary professionals and owners. Sadly, earlier this year we had case of a dog that had eaten raisins and was presented 36 hours after ingestion due to vomiting. By this time the dog was already in renal failure and the owner elected euthanasia.
A recent report evaluated 139 dogs with ingestion of grapes or raisins. Dogs were included if they had confirmed grape or raisin ingestion (witnessed ingestion, grapes or raisins in vomitus,
stool, or oral cavity, or evidence of ingestion such as damaged packaging) or if they showed clinical signs or azotaemia after suspected ingestion.
- The majority of dogs received gastric decontamination (emesis and/or activated charcoal).
- The longest time to presentation in a dog with evidence of raisins in the vomitus was 13 hours and for evidence of grapes in the vomitus was 8 hours.
- Vomiting was the most common signs overall.
- Eight dogs of 120 with biochemical analyses had evidence of kidney injury.
- One dog developed acute kidney injury after ingestion of only 1 g of grapes/kg despite presentation at 2 hours and early gut decontamination.
- Of note, not all dogs that developed azotaemia or kidney injury showed clinical signs.
- There was only one fatal case and this was in a dog that presented at 48 hours after ingestion of 3 g/kg of raisins, developed acute kidney injury and died from complications of continuous renal replacement therapy.
The current understanding is that grape and sultana/raisin/currant toxicity is idiosyncratic and it is still not possible to determine a toxic dose since the risk factors remain unknown. Although it likely that a single grape or piece of dried fruit is unlikely to be a risk, dogs ingesting more than this should ideally receive an emetic and repeat dose activated charcoal. The authors of the above study concluded that based on the low prevalence of acute kidney injury and the retrospective nature of their study, no conclusions could be made regarding optimal length of hospitalisation following grape or raisin ingestion and 48-72 hours as previously recommended is likely appropriate.
Owners should be fully informaed of the risks and it may be decided to send the dog home after gut decomtamination with instructions to return if any signs start, particularly vomiting, at which time IV fluids and bloods for renal parameters are indicated. Certainly, any dog with vomiting and late presentation after ingestion of grapes or dried fruits should be admitted and assessed for kidney injury.
