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Friday, 29 July 2011

Dog and Cat Poisoning - Common Poisons Part 2

Welcome to PercyPods Pet Emergency blogs. This week is the last blog on poisoning in dogs and cats for a while. The poisons we are going to discuss this week are pyrethrins and pyrethroids which are contained in some anti-flea products, metaldehyde which is in snail bait or slug pellets, ethylene glycol which is in antifreeze, and non-steroidal anti-inflammatory medications such as ibuprofen, aspirin and paracetamol or acetaminophen.

Pyrethrins and pyrethroids

Okay so let’s get started by discussing pyrethrins and pyrethroids. These substances kill insects and they are found in a large number of preparations that are readily available from a variety of outlets such as supermarkets, garden centres, DIY stores and of course the internet. Most relevant to us here is that these substances are found in a number of preparations that are sold for controlling flea and lice infestations in dogs and cats. We should stress that we are not saying that it is not safe to use these products; they are widely used without a problem in many animals and many households. The point however is that, as for many other products, they can be dangerous if they are not used correctly and in keeping with the recommended guidelines. We as vets see enough pets poisoned by these products to make us want to mention them in this blog.

So pyrethroids are now most commonly used in dogs and cats as so-called ‘spot on’ preparations that are applied onto the animal’s skin. This is usually done by parting the hair on the back of the animal’s neck and squirting the product out of a pipette-style packet. You are probably familiar with what we are referring to and examples of products that you may have used include those made by Bob Martins and Advantix made by Bayer Animal Health.

By far the most common scenario we as vets see are cats that are poisoned when their well-meaning carers apply products that are manufactured for use on dogs onto the cat. Sometimes this is by mistake when the owner does not realise that they have in fact bought a product for dogs; in other cases the owner mistakenly thinks that it will be ok to say apply half of the dog pipette onto the cat. Cats are very sensitive to this type of poisoning and you should only ever use a product sold for cats on cats; you should also make sure that you use the right strength of product, so for example don’t use a product designed for adult cats on kittens.
Another way in which cats have been poisoned is when a dog in the house is treated with one of these spot-on preparations and then, before the solution has dried, a cat either touches the area or licks the product directly off the dog.

The poisoning that pyrethroids cause in dogs and cats is similar for both species as is the treatment, although as we have said, cats are more susceptible and most cases seen by vets are cats. Signs of poisoning usually occur within a few hours, often sooner, and they mostly affect the nerves. Animals may show signs such as drooling and wobbliness, and flicking of the paws or twitching of the ears may occur in cats. Severely affected animals may become very depressed, show violent muscle tremors or seizure, and poisoning can be fatal without urgent treatment.

So if you think your pet has been poisoned in this way you should ring your veterinary practice immediately for advice. As always, be prepared to try and provide as much information as possible – what product was used? What does it contain? And so on. In some cases your practice may recommend washing the product off your pet but they will want to be sure that this is safe to do which will very much depend on the information you provide. The product can be washed off using a baby shampoo or mild detergent such as washing up liquid mixed with lots of tap water at room temperature but it is very important not to get this into your pet’s eyes. Make sure the water is not too hot or too cold and dry your pet thoroughly afterwards. But please bear in mind that it is not safe to try and wash an animal that is struggling or resisting or showing any sort of abnormal signs at all; it is very much something only to be considered in an animal that is cooperative and only very soon after the product has been applied. We would urge you to always ring your practice first to get their advice about whether washing your pet is appropriate and safe.

In the vast majority of cases the safest thing is for you to arrange to take your pet to your vet practice. Depending on how long it has been since the product was applied and what signs your pet is showing, he or she may need to be anaesthetised to be washed thoroughly. They may also need treatment with drugs to control nervous signs such as tremors and seizures as well as a fluid drip into a vein; in some cases your pet may need to remain anaesthetised for a lengthy period of time. You should note that this treatment may need to be continued in the worst cases for 3 days for example. However on the plus side even the most severely affected animals have a good chance of making a full recovery if they receive treatment as soon as possible and for as long as necessary.

Before we move on to the next type of poisoning then, just to reiterate that poisoning with pyrethroids is seen most often in cats when an anti-flea product intended for dogs is used on the cat. Poisoning can be life-threatening and you should really avoid using dog products on cats.


Okay so let’s move on and talk about something called metaldehyde. Metaldehyde is found in some pesticides that are used to kill slugs or snails. The most common type are pellets which are usually blue or green in colour. These pellets also contain cereals and other additives which make them tasty to dogs. As always cats are more picky and this type of poisoning is much less common in cats. It is worth knowing that although pellets are the most common type of slug or snail bait, some preparations also come as liquids or powders. Unfortunately some of these preparations also contain other types of poisons which can add to the problems they cause.

So dogs and cats become affected when they eat the poison. In our experience in many cases this happens when the slug pellets have been put away in the shed or garage and a dog gets into the room and helps themselves to the pellets which, as we mentioned, are tasty to dogs. When questioned thoroughly owners of poisoned dogs often realise that they had some slug pellets in the shed or garage and that the dog could well have got to them. It is very important to make sure that these products are stored securely and well out of the reach of hungry canines! Of course some dogs poison themselves by eating slug bait that has actually been put down in the garden or in public places such as parks and woodland.

Metaldehyde causes problems in dogs and cats by causing excessive stimulation of the nervous system. Signs often develop very quickly, for example in less than an hour, but in some cases it can take longer. The typical signs shown include muscle twitching and tremors and seizures or fitting. These signs can really be very severe and urgent treatment is recommended. One of the consequences of these tremors and seizures is that your dog will become very hot, a bit like a dog with heatstroke, and this makes the situation worse still. Metaldehyde poisoning is sometimes referred to as the ‘shake and bake syndrome’ because of this combination of signs.

Because slug bait poisoning can be very severe, including leading to death, it is important that all cases are treated urgently as emergencies and you should ring your vet practice as soon as you become concerned that your dog may have been poisoned. Inducing vomiting at home is typically not safe in these dogs because of the signs they are showing; we discussed this at some length in the first of these blogs so please read that if you haven’t already.

In the vast majority of cases the safest thing is for you to arrange to take your pet to your vet practice. Your vet is likely to want to anaesthetise your dog to wash out his or her stomach thoroughly. After that your dog may also need treatment with drugs to control nervous signs as well as a fluid drip into a vein; in some cases we have to keep your dog anaesthetised for a lengthy period of time. Intensive treatment often needs to be continued for one to three days. However on the plus side even the most severely affected animals have a good chance of making a full recovery if they receive treatment as soon as possible and for as long as necessary.

Ethylene glycol

Okay so let’s move on from metaldehyde and talk about ethylene glycol. Ethylene glycol is a sweet-tasting and sweet-smelling liquid used primarily as an antifreeze, screen wash and windshield de-icing agent. Dogs and cats are most commonly poisoned by ingesting antifreeze and this tends to occur in one of two ways.

The first is when people drain their car radiators and fail to dispose of the used antifreeze safely. Poisoning is most likely to occur in late autumn and early spring when antifreeze usage increases. Used antifreeze should be drained into clean labelled containers, for example plastic bottles, which are then tightened securely. Depending on where you live and what facilities are available locally, this used antifreeze may be disposable at a local garage, some of whom may actually be able to recycle it, or alternatively may be handed in to a local waste disposal centre.
Used antifreeze should NOT be poured into floor drains, sewers, or on the ground, and it also should not be mixed with other waste products.

The second most common route in which dogs and cats are exposed to antifreeze is when containers of new unused antifreeze are not stored safely. Safe storage means in sealed containers out of reach of animals and indeed children.
Another route in which dogs and cats may come across antifreeze is from outdoor ornamental ponds. Some people add antifreeze to these ponds to prevent freezing and animals may drink from them.

So what is the problem with antifreeze? What does it do to dogs, cats and indeed humans? Well, the most severe problem is injury to the kidneys leading to kidney failure. Some animals also show nervous signs and in general the more antifreeze is consumed the more severe the resulting problems are. Within one hour of ingesting the antifreeze animals may become depressed and wobbly; they may also vomit and some animals drink more water. In severe cases seizures, coma and death may occur.
After these initial signs, some animals – especially dogs – may appear to get better for a while. However they then start to show other signs as kidney failure sets in.

You should contact your veterinary practice immediately if you think your pet may have been exposed to antifreeze. In some cases it will be appropriate to make your pet vomit the antifreeze back up. Your vet is likely to run some blood and urine tests to check for signs of kidney failure.

Antifreeze poisoning is one type of poisoning for which an antidote or specific treatment does exist, although this can only be used before kidney failure develops. Once you pet has kidney failure, there is no indication to use an antidote and a fluid drip into a vein becomes the most important treatment. The first and best antidote is a drug called 4-MP or fomepizole. However this drug is not available in all areas and all countries and where it is not available, for example in the United Kingdom, the next option is to use alcohol as an antidote. In some cases this is administered into a vein, in others it may have to be given directly into the stomach via a stomach tube. However please note that you should never administer alcohol to your pet yourself; a specific type of alcohol is needed and alcohol administration carries some significant risks if not done properly. This is very much something that has to be done with your pet hospitalised at the practice.

For animals already in kidney failure, the extent of damage to the kidneys will dictate how long they need to be in the hospital, whether they need further treatment and also their chances of making a full recovery. The outlook for dogs and cats poisoned by antifreeze depends on a number of things most important of which is how quickly they receive the right treatment. Treatment with an antidote usually needs to be started within a few hours of the animal being exposed to the antifreeze to be successful. Once severe kidney failure sets in unfortunately the outlook is extremely poor; the kidney failure is typically not reversible and putting your pet to sleep may be the kindest option. Sadly many pets are not seen by vets until they have already reached this stage.

The take home messages therefore are very much that prevention is key and also that you should contact your veterinary practice to arrange an emergency consultation the moment you become concerned that your pet may have been exposed to antifreeze.

Non-steroidal anti-inflammatory drugs

Okay so let’s now move on and finish this podcast by talking about poisoning of pets by a group of drugs known as non-steroidal anti-inflammatories. These drugs can be considered in three groups for our purposes here and let’s talk about each in turn.

The first group are drugs such as ibuprofen and naproxen which are sold widely over-the-counter for use in people. This group also includes drugs that are specifically designed for use in animals such as carprofen or meloxicam. These drugs are used as anti-inflammatory pain-killers as well as to treat fever.

As is often the case, poisoning by this group of non-steroidal anti-inflammatories is more common in dogs than cats. Poisoning occurs when the dog eats an excessive amount. However it is very important to note that we also see a number of cases in both dogs and cats where either the owner accidentally gives their pet way too much of a veterinary drug that has been prescribed for treatment, or decides to administer a human drug to their pet without first checking that this is okay.

Poisoning by these drugs can cause a number of problems, the most common and severe of which are injury to the stomach and intestines, including possible ulceration, and kidney failure. Poisoned animals may vomit or have diarrhoea, both of which may contain blood in them. Bloody vomit often has an appearance of ground coffee. Both of these problems may require your pet to be hospitalised for treatment including a fluid drip into a vein, various medications and potentially even surgery. These problems can be very severe, including life-threatening, so it is a very serious matter.

The second type of non-steroidal anti-inflammatory drug that we would like to mention is aspirin. Again aspirin is very widely available over-the-counter. It is used to treat specific problems in dogs and cats but as with people, if too much is given, severe problems can occur. This is especially the case in cats and if you are ever considering giving aspirin to your pet of your own accord, we would strongly encourage you to speak to your vet first.
Problems that aspirin can cause include injury to the stomach and intestines; kidney failure; nervous system signs; breathing problems and unexplained bleeding.

The third type of non-steroidal anti-inflammatory drug that we would like to mention is acetaminophen which is also known as paracetamol for example in the United Kingdom. Acetaminophen is used extensively by people and is widely available over-the-counter. It is contained in a variety of preparations either on its own or with other drugs including for example aspirin and codeine.

Acetaminophen has been used in dogs to treat certain conditions. However it is not used very widely nowadays given that there are now a number of drugs specially produced for animals. Again, acetaminophen is only safe in dogs if it is used at the right doses and you should definitely consult your vet practice if you are considering giving acetaminophen to your dog.
Now, it is very important to realise that acetaminophen should NEVER EVER BE GIVEN TO CATS. It is very very dangerous to cats and even tiny amounts can be life-threatening.

The two main problems that acetaminophen or paracetamol can cause are liver failure and damage to red blood cells; red cells in the blood carry oxygen around the body. Animals with liver failure may vomit, go off their food, and become jaundiced. Jaundice is when the gums, the skin and the whites of the eyes take on a yellow appearance.
Damage to red blood cells may make your pet’s gums look brown, like a chocolate appearance, or blue or purple. Some animals, especially cats, may also develop swelling of the face or paws, and breathing problems. These signs may start within a few hours of your pet being poisoned by acetaminophen.

It is very important that you ring your vet practice immediately if you think your dog and especially your cat has been poisoned by acetaminophen. There are several aspects to the treatment of acetaminophen or paracetamol poisoning which might include making your pet vomit or washing out their stomach; admitting them to the hospital for a fluid drip into a vein; and providing them with a variety of different medications.

Acetaminophen poisoning is one type of poisoning for which a couple of different antidotes or specific treatments exist and may prove life-saving. The first antidote is a drug called N-acetylcysteine which may be given by injection into a vein; there are also tablets available to be given by mouth. Treatment may need to be given for up to 2 days. Vitamin C is another drug that your vet may decide to use to treat paracetamol poisoning and there are various other options too.

The outlook for dogs and cats poisoned by acetaminophen or paracetamol depends on how much they consume, how long it is before treatment is started and whether treatment can be continued for as long as necessary. Acetaminophen poisoning can be life-threatening and we cannot stress enough how careful you need to be, especially to make sure that cats never get exposed to this drug.

Okay so that brings us to the end of this PercyPods Pet Emergency blog. We hope that you have found it useful and learned a little about some of the more common poisons affecting dogs and cats. The next blog will be in approximately 2 weeks time when we will move on from poisoning to discuss vomiting. Before we sign off just to remind you that you can contact us in various ways. Via email on; via the PercyPods Facebook page; or via Twitter on @PercyPods. We would really love to hear your comments on this podcast as well as suggestions for future topics. Also don’t forget to subscribe for future episodes via the email feed. So thank you for reading and until next time, may you and your pets be safe.

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