When 6 month old “Splodge” the spaniel was presented to me last week, he was showing signs of a very nasty bout of gastroenteritis and was feeling extremely sorry for himself.

His owner told me that Splodge had had terrible vomiting and diarrhoea the previous night. Splodge then proceeded to give me – and everyone in the waiting room – a full demonstration!

To my surprise, I noticed that Splodge had passed something that looked like an egg! Surely not? I then realised that it was an acorn. His owner commented that Splodge had been eating acorns with some relish recently!

Alarm bells rang in my head, and I immediately contacted the Veterinary Poisons Information Service. This excellent organisation offer 24 hour advice to vets on all substances known to man, and are rapidly able to tell us if a substance is toxic, and if so, what the most appropriate treatment is.

They informed me that acorns can cause severe gastroenteritis (no surprises there then!) but also kidney failure if large enough quantities were eaten. Smudge was immediately admitted to hospital.

Fortunately, blood tests showed that his kidneys were in reasonable shape, but he was kept in on a drip for 2 days to keep him hydrated until his gastroenteritis settled down. He has made a good recovery.

Splodge may not be the only animal affected by acorn poisoning this year. Every few years, there is a particularly heavy crop of acorns, and warnings are put out in the veterinary and farming press.

Cattle and sheep may suffer acorn poisoning, so in “acorn years”, farmers are advised to fence off areas where oak trees grow. This year has been declared as such a year.

Younger, green acorns (like the ones that are present at this time of the year) are more toxic than brown ones. The toxins that cause all the problems are called tannins. Some species, including pigs and squirrels, do seem able to eat acorns without adverse effects. This may be partly due to different metabolic pathways in their bodies which enable them to handle the tannins, but may also be partly due to the fact that they discard the acorn shell, where the highest concentration of tannins are found.