Karaka (Corynocarpus laevigatus) are a beautiful native New Zealand tree species with broad shiny leaves that grows throughout the North Island and the northern South Island. Karaka are an important part of NZ’s natural ecosystem with Bellbirds & bees feeding on the small Karaka floweres in spring (August – December). Kereru (wood pigeons), Tui, Kaka and small lizards feed on the fruit (January – April) and thereby help disperse karaka seeds. Less conspicuous but other equally important native insect species such as leaf-tyer moth caterpillars, giraffe weevils, longhorn beetles, karaka gall mites and karaka deadwood weevils also depend on karaka for habitat and food.
The importance of karaka to us as dog owners is that the yellow – orange coloured fruit contain the alkaloid toxin, karakin. Karakin is highly poisonous to people and dogs. Interestingly, Maori developed methods of detoxifying karaka fruit by cooking it in a hangi and then extensively rinsing the fruit or by boiling the fruit in thermal pools for extended periods after which the fruit became safe to eat. Apart from being an important food source, other parts of the tree were used to treat wounds and make canoes.
Karakin is present in many parts of the tree but especially in the fruit and the hard kernel within. As the fruit ripens it changes colour, progressing from green to yellow to orange before it falls to the ground. Once on the forest floor the fleshy fruit is lost and the kernel remains. It is here that most dogs become poisoned when they pick up and eat the whole fruit or kernels.
There is frequently a delay of 1 to 2 days after the dog has eaten the fruit to when it shows signs of poisoning. Signs of poisoning caused by Karakin relate to it being a neurotoxin. Initially the patient may be mentally confused and weak with intermittent vomiting. Hind limb paralysis, progressive generalised muscle weakness and seizures occur as the disease progresses, following which the dog may die.
Since Karaka poisoning is so serious it is important that we have a simple plan in mind to protect our dogs and family. Here are the basic steps I use to protect my dog, Poppy:
- I’ve learnt to recognise karaka trees and know that they fruit in summer and autumn (January – April). Karaka trees are common in forests and reserves, and are recognised by their broad, deep green coloured leaves. They grow to about 15 metres and often have smaller karaka seedlings growing around them. The oval fruit become orange when mature and grow up to 4cm long. I now know where the karaka are and I supervise Poppy carefully when she’s around them in summer. If Poppy was a young puppy or dog that mouthed or ate things on the ground on walks I would avoid the karaka trees altogether in summer – autumn.
- If you think your dog has eaten karaka fruit, call us to let us know the situation and bring it straight to The Pet Doctors so we can induce vomiting immediately. We don’t advise waiting to see if signs develop before coming to the practice because the fruit will have traveled further down the gut and may not be able to be completely removed by vomiting or enemas.
- If your dog is already showing signs of karaka poisoning, again telephone The Pet Doctors to let us know and bring it to us immediately. That way we can make preparations in hospital based on the signs your dog is showing while you are in transit and can start treatment more quickly.
- Keep your dog’s pet medical insurance up to date. This is exactly the circumstance where your pet insurance will be of benefit to you because, depending on how much treatment is required, this visit is likely to be expensive. You will be worried about if your dog will survive the poisoning and it is a great comfort to know that you have your financial bases covered so you can give them the best care.
Unfortunately there is no known specific antidote for karakin. Treatment is therefore mainly supportive in nature – removing as much fruit as possible from the stomach (by inducing vomiting or performing gastric lavage) and intestines (enemas); IV fluids & tube feeding to maintain nutrition & hydration; Medications to control seizures, help muscle tone; Physiotherapy to stop muscle wasting from paralysis; etc. If successful, treatment may be needed for several weeks and neurological function may take 6 – 8 weeks to return to normal. This is definitely a disease where ‘prevention is better than cure.’