OCTOBER 26, 2012
Brunfelsia pauciflora in full bloom. Botanical gardens, Brisbane
Nature can be deadly, and colour in nature is often tied to how deadly or poisonous something is. Of course that is not always the way. Funnel web spiders, for example – not so colourful really but incredibly deadly! So how do we tell which colours are safe and which are poisonous? Colour may just surprise you, and what looks to be pleasant and pretty can be very deadly for our pets, who are often quite indiscriminate about what they put in their mouths. Like small children.
There is a very pretty, fragrant shrub, or small tree, growing in many yards across Australia, particularly in northern NSW and Queensland, known as Brunfelsia pauciflora (or Yesterday, today, tomorrow). The plant is so called because of the way the flowers change colour over a couple of days after blooming. Brunfelsia species are native to South and Central America and the West Indies. It is commonly seen in gardens in the southern states of the US also, where it flourishes in the warm weather.
The most common variety has purple or blue flowers which change to white, though there are variations with pink, yellow and red flowers. All parts of this plant can be poisonous to dogs but it is often the seed pods falling off the tree that are particularly attractive and often eaten.
It is proposed that there are three different types of toxins in the Brunfelsia plant which cause the clinical signs seen. These include: – Brunfelsamidine which excites the nervous system and can cause seizures and death. – Hopeanine, a nerve depressant that may contribute to paralysis or weakness, and – Scopoletin or gelseminic acid (I guess they haven’t decided which), proposed to relax the arteries and drop the blood pressure and heart rate.
Sounds pretty sinister, and it certainly can be. One of the problems with the toxicity is that it may take 15-18 hours for the signs to be revealed. Pet owners may not realise that the signs are representative of behaviour performed that many hours prior. So it can be tricky for us to work out that Brunfelsia is implicated in some of our patients.
The signs we see in dogs that have chewed on the plant generally include gastrointestinal and central nervous systems signs, such as depression, vomiting, diarrhoea, muscle tremors and seizures. Some will drool profusely and may look like cane toad intoxications. Occasionally sneezing will be the first sign seen, which I thought was odd but I recently saw two cases from the same household (same night) who were both reported to have been sneezing before other signs developed. Apparently oro-nasal irritation can occur when the plant is eaten.
The signs then are not that different to a variety of other types of poisoning so it can be difficult to diagnose until certain revelations are made. The main one is the detection of plant material in the gastrointestinal tract (either in vomitus or faeces). More specifically, when a rectal examination is performed, finding large amounts of seed pods in the faeces is a sure way to gain a diagnosis. The seed pods are often chewed and fragmented but very typical in appearance.
Poisoning with Brunfelsia can be mistaken for other types of toxicities such as strychnine and snail bait intoxications, or exposure to certain types of illicit drugs. While it can look like toad intoxication initially, the dogs lack the red gums and ropey saliva that toad exposure tends to cause and diarrhoea is uncommon in toad toxicities. Common culprits for exposure are young dogs who do seem to be a little less discriminating of what they chew on than older dogs.
There is no specific antidote and like many poisons, treatment consists of a few very straight forward steps. Though I do need to add that recovery of your pet who has eaten the plant may not be very straight forward. The steps to treat most toxicities, especially where the cause is unknown, includes the ABC’s -> ensuring airway is clear and open, the breathing is adequate to maintain normal oxygenation and the circulatory system is functioning appropriately (heart is pumping normally and blood pressure is good).
Supportive care is essential to ensure the ABC’s remain adequate, so intravenous fluids will be provided and possibly flow-by, nasal or in-cage oxygen if there is an indication for it. Seizures will need to be controlled if they are occurring and if the patient is overheating from tremoring, cooling and medications to control the tremors may be required. If seizures are difficult to control, general anaesthesia may need to be performed to completely relax the body and central nervous system.
One of the most important steps for any toxicity though, and not least for Brunfelsia toxicity is decontamination. Decontamination is necessary to help eliminate the toxin from the body as quickly as possible and help control or halt any further progression of the intoxication. Decontamination in a dog that is conscious and mentally appropriate may include the induction of vomiting to help remove sources in the stomach. Making a dopey dog vomit can be dangerous because they may not be able to protect their airway and aspiration of vomitus could cause pneumonia to develop.
If the dog is quite dopey or seizuring, general anaesthesia is best performed, so that the stomach can be lavaged (essentially “pumping the stomach”). An endotracheal tube will be placed to protect the airway from water being flushed the wrong way. Plant fragments can then be “cleaned” out of the stomach and help reduce further absorption of the toxins. While asleep, the other end can be flushed out as well to remove any material that has already made its way to the dog’s rectum. Enemas can also be performed on conscious dogs where plant material is present.
Once the top and bottom ends have been cleared out, activated charcoal can be given to the patient. This acts by binding any toxins still in the gastrointestinal tract, where flushing and lavage have not reached. Caution needs to be used though because once again, if charcoal ends up in the lungs…. So we generally wait until the patient is conscious and able to eat the foul stuff on their own. It is amazing how many young dogs will eat a bowl full of charcoal and dog food!
Recovery time really depends on how sick the dog was when they arrived at the clinic. I have seen mildly affected dogs go home the next morning, while those who present seizuring may require a couple of days on intravenous fluids and anti-seizure medication until the toxin clears from their system.
The other issue that may cause a problem to the pet owner is removing the source of the poison. Yes, that means removing the ENTIRE plant! As all parts of the plant are toxic, every last bit needs to be removed. One of my colleagues saw a patient who was ill after chewing on the roots left behind after shrub removal.
The best advice to anyone with pets – Don’t plant a “Yesterday, Today, Tomorrow” plant in your garden! Part of responsible pet ownership is keeping them safe in your yard as well as outside of the yard. Pretty plant versus loved family member? The choice is simple.