Ik zou 't helemaal niet laten eten..
Horse chestnuts/Conkers:
en deze zijn tamme kastanjes
The Horse Chestnut is a large deciduous tree, commonly found in parks and urban areas and its seeds, the horse chestnuts or “conkers”, usually ripen from August to October. If conkers are eaten in large quantities by dogs, for example, the animals can develop dramatic sickness and diarrhoea and excessive salivation within an hour or so of eating the conkers. There have also been a few isolated cases where plant material or actual whole conker has obstructed the gastrointestinal tract. Fortunately, for animals that show signs related to the ingestion of large numbers of conkers they often respond well to supportive veterinary treatment and care. In the infrequent cases where obstruction is suspected, surgical removal of impacted plant material may be necessary.
Oak - acorns:
The Oak tree is well known for its production of acorns, which often appear in the autumn months. If pets, such as dogs, happen to eat acorns in large numbers, the result can be severe diarrhoea and vomiting. These signs occur because of a substance called ‘tannic acid’ in the acorns. Similar to accidental ingestion of conkers, if eaten by dogs, there can also be a risk of gastrointestinal obstruction by the acorn nut.
http://jerseygreyhounds.webs.com/dogsandpoisons.htm
Many people do not realize that acorns are toxic to dogs. The toxic principle is unknown, but they do contain gallotanins, a combination of gallic acid and tanic acid. Oak trees are very common and most people don’t have problems, but they are not the trees of choice to have in a backyard full of pets. Acorns, oak buds, leaves, and drinking water that acorns and oak leaves have soaked in, have all caused symptoms of oak poisoning.
Dogs have been poisoned by drinking water that oak leaves have soaked in. Two Chihuahua puppies were seen chewing on a couple of acorns. They developed a bloody diarrhea and their kidney values became markedly elevated. In spite of emergency treatment, they died of renal failure.
Acorns could potentially cause an obstruction of the intestines, but this would probably occur in a smaller dog.
If possible, minimize your dogs’ exposure to acorns, and be especially careful that their water bowl is not contaminated.