Dr Liesel van der Merwe is a small animal medicine specialist. Send her your questions: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Dr Liesel van der Merwe

Several times over the last year I have seen information disseminated about the use of medications to assist with poisoning in your dogs. I think it is very important for all out there to realise that without the antidote for the most common poisons used – carbamates and organophosphates – your dog will likely die if it has taken in a big enough dose.

Dogs are unfortunately poisoned in a street or suburb to give criminal elements access to properties. The most commonly used poison is Temic, commonly known as two-step. This falls into the organophosphate and carbamate group of poisons.

A brief overview of the nervous system: the nervous system is broadly divided into two main groups – somatic, which controls all our conscious movement and autonomic, which controls all our subconscious functions.

The autonomic system is further divided into the sympathetic and parasympathetic systems. The sympathetic system would drive reactions of acute adrenalin-related stress, such as being chased by a lion. The parasympathetic system manages our baseline functions, which allow normal function such as digestion, a normal heart rate and normal breathing.

These poisons work by over-stimulating the parasympathetic system. They work on receptors for all the smooth muscle, which are related to all our organs and glands and intestines; as well as on the receptors related to all our striated muscle, which are all the muscles of our skeleton which enable us to move around and breathe.

The poison is often thrown over the wall in pieces of meat and your dog can show symptoms within 20 minutes of eating. The symptoms are very variable. Because the glands are stimulated, increased salivation occurs as well as vomiting and diarrhoea. The whole gastrointestinal tract is overactive.

The heart rate slows down dramatically and breathing becomes difficult due to bronchoconstriction and increased secretions into the lungs. Ultimately dogs die due to respiratory failure. The skeletal muscles will show tremors and twitches, which may be severe enough to interfere with walking.

A slightly delayed symptom is that of muscle weakness, which follows on the initial overstimulation. The antidote does not work for the muscle weakness. This can affect the entire body or just the breathing muscles. If the breathing muscles are affected, artificial ventilation will be required – as with a snake bite. Weak muscles in the remainder of the dog are not of a major concern as the effect is transient as the poison wears off – usually a few days.

The responses to the poison are catastrophic and life-threatening. The antidote must be given to reverse these changes and will need to be given intermittently until the poison has worked itself out of the system.

Additionally we use drugs to try to remove the poison from the system and prevent further absorption from the intestine. This is where the activated charcoal has a role to play. It will bind any poison left in the intestine. This is usually minimal as the dog is already vomiting. It also helps the poison leave the system via the bile (the drug is excreted through the liver).

Activated charcoal WILL NOT reverse any of the clinical signs evident. Do not waste time waiting for activated charcoal to work at home. Rather get your dog to the vet as soon as possible where your dog will be treated with both the antidote as well as activated charcoal.

The antidote doesn’t block the poison, but treats the symptoms. So, the treatment course is as long as it takes for the toxin to leave the system. As soon as the antidote – Atropine – is given, the bronchi relax, allowing big easy breaths and the heart rate increases. The antidote unfortunately has no effect on the skeletal muscles, so cannot reverse the muscle weakness.

There is also a new drug on the market – IV intralipid – which can be given IV soon after poisoning and will bind the poison before it can affect the nerves and muscles. This may reduce the duration of treatment, but the antidote and activated charcoal will still be required.

If you actually see your dog eat something with suspected poison in it, make him vomit using a damp ball of powdered washing powder, then you can dose activated charcoal and load the dog up to the vet. In any other situation the poison causes vomiting. Dosing activated charcoal without the antidote is useless. 

Atropine is a dangerous drug and can cause death from cardiac arrhythmias, so it is generally not dispensed as an “in case” drug. I have also seen it used incorrectly when a patient is experiencing seizures and has not been poisoned, so it is not a safe drug in inexperienced hands.

My best advice is to get your dog to the nearest vet. If you have problems with poisoning in your area, speak to your vet about an emergency kit. Also make sure your family is safe – the property is now a target.