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Friday, 29 July 2011

Dog and Cat Poisoning - Common Poisons Part 1

Welcome to PercyPods Pet Emergency blogs. This week: why having a sweet tooth can be deadly for your pet, two different causes of kidney failure, and the perils of rat poison.

So in our first blog we looked at some general information relating to poisoning in dogs and cats. We are now going to move on and discuss some of the more important poisons. Although there are a very large number of potential poisons, many of the cases that we as vets see are the result of the same substances and we are going to concentrate on ten of these in these podcasts. This week’s podcast will look at xylitol, grapes/raisins/currants, lilies, chocolate and rat poison. The next blog in 2 weeks time will look at pyrethrins and pyrethroids which are contained in some anti-flea products, metaldehyde which is in snail bait or slug pellets, antifreeze, non-steroidal anti-inflammatory medications such as ibuprofen, and paracetamol or acetaminophen.


Okay so let’s start with xylitol. Although xylitol poisoning is not that common, it is a relatively new poison to have been uncovered. Xylitol is a naturally-occurring sugar alcohol found in small amounts in a variety of fruits and vegetables. However it is also extracted commercially and used as a sweetener in low carbohydrate and diabetic products. These products include for example baked goods such as cakes and biscuits. The use of xylitol has also been increasing due to its effects in reducing tooth decay. This has led to xylitol being included in products such as chewing gums, sweets and toothpastes. It is important to realise that manufacturers do not have to specify that a product specifically contains xylitol so just because it does not say on the wrapper that the product contains xylitol, it still may and we need to be aware of this.

Xylitol poisoning has been reported in dogs but at the time of this blog there are no reports of clinical poisoning in cats. Poisoning occurs when the dog eats a product that contains xylitol. The two main problems that this can cause in dogs are hypoglycaemia, in other words low blood sugar, and liver failure.

Low blood sugar occurs because in dogs xylitol increases the production of insulin; this effect does not occur in people however. The effect of xylitol in lowering blood sugar is what we call ‘dose-dependent’; that means the more xylitol a dog eats, the lower blood sugar is likely to fall. Blood sugar may fall so low that the dog starts to show signs such as lethargy, weakness and depression. In severe cases wobbliness and even seizures may occur and this is a life-threatening emergency. These signs may develop within one hour of the dog eating the xylitol, but they can also take longer to come on.

Xylitol can also cause liver failure and this can actually occur even if only a very tiny amount has been eaten. It is for this reason in particular that we recommend that all dogs that have eaten xylitol are treated aggressively. Signs associated with liver failure take longer to develop than those from low blood sugar, for example up to 3 days. They include evidence of bleeding say from the gums or in faeces, as well as signs of jaundice where the dog’s gums, skin or whites of the eyes take on a yellow appearance.

We would strongly encourage you to contact your veterinary practice if you think your dog may have ingested some xylitol regardless of the amount. Depending on your individual dog, it may or may not be appropriate to induce vomiting; this was discussed in greater detail in the first of these blogs. Alternatively your vet may want to wash out your dog’s stomach under a general anaesthetic. Additional treatments that may be required specifically for xylitol poisoning include sugar supplementation and treatment for liver failure. Your vet will be able to discuss this with you in more detail.

However it is worth saying that if your dog develops severe signs such as seizuring or being in a coma after eating a product containing xylitol, it may be appropriate for you to try and administer some sugar at home before taking him or her to your practice as these signs may be due to severely low blood sugar. Of course you must be careful not to get bitten and we also would not recommend that you actually try and feed the sugar to your dog. These animals are usually not in a condition where they are able to swallow and trying to force the sugar down them is not a safe way forward. The best thing for you to do is to get some honey or mix some normal sugar with water and rub this onto your dog’s gums. If this helps his or her signs, you can repeat it as often as you need to. However we must stress that this is very much a short-term life-saving measure while you make your way to your veterinary practice; it is not safe to try and continue to treat these dogs at home.

Tests that your vet may want to perform when they see your dog include blood tests to check blood sugar and to check for signs of liver injury including how well your dog’s blood clots.

The outlook for dogs that have been poisoned by xylitol really depends on two things. The first is whether they can receive treatment in time and for as long as is required. The second is how severely affected the liver is. Regrettably some dogs develop severe liver failure and putting them to sleep becomes the kindest option.

Before moving on from xylitol, just a word of caution. There are some products on the veterinary market designed for use in dogs to improve the condition of their teeth and help prevent tooth decay. Some of these products contain xylitol. As we are unsure at the moment exactly how xylitol causes problems, we personally would not recommend the use of these products in dogs. To us it does not seem a risk worth taking when we know how severe the consequences can be.


Okay so now let’s move on and talk about poisoning from grapes, raisins or currants. It has been known since the late 1990s that these fruits can be poisonous to dogs. However at the time of this podcast there have been no reports of poisoning occurring in cats; nevertheless we cannot be sure that they are not harmful to cats and it is best to try and avoid cats gaining access to grapes, raisins or currants. Thankfully cats are unlikely to eat such items anyway – in general cats are less likely to poison themselves than their doggy counterparts.

Poisoning in dogs is associated with injury to the kidneys and in the worst cases life-threatening kidney failure can occur. At the moment it is not known exactly how these fruits harm the kidney. However one point that is essential to realise is that poisoning in dogs may occur following ingestion of all types of fresh grapes and commercially available raisins including organic ones.

What is especially worrying about grape, raisin and currant poisoning in dogs is that there appears to be no way of predicting that this might occur. Many poisons are ‘dose-dependent’ which as we said a few minutes ago means that the more the dog eats, the more likely it is that poisoning will occur and the more severe the signs are likely to be. However at the moment it is suspected that poisoning in dogs due to grapes, raisins and currants is not dose-dependent. This means that one dog could eat a whole bunch of grapes many times throughout their life without ever having a problem while on the other hand another dog might eat just a few grapes and develop kidney failure. It is because of this unpredictable nature of the poisoning in dogs that we recommend that no dogs should be fed grapes or any products containing raisins or currants, and we also recommend that any dog that does eat any of these fruits, no matter how little the amount, is treated immediately.

Okay so what signs might your dog show if they are suffering from this type of poisoning? Well, vomiting is reported in almost all cases and this usually occurs within 24 hours of ingestion; grapes, raisins or currants may be identified in the vomit although I am not sure how many people are willing to actually inspect their dog’s vomit! Other signs that may occur include loss of appetite, lethargy, diarrhoea and signs suggestive of pain in the dog’s stomach area or abdomen.

As most dogs suffering from this type of poisoning are already vomiting, it is usually not necessary for your vet to make your dog vomit or to wash out his or her stomach to get rid of the fruit. However they may recommend that your dog is fed some activated charcoal for a while; this is intended to basically mop up any of the poison still left in your dog’s stomach or intestines. The poison is then passed out of your dog in their faeces.

Your vet is likely to run some blood and urine tests to check for signs of dehydration and kidney failure. In many cases it may be appropriate for your dog to be admitted to the practice to receive a fluid drip into a vein for 2 days or possibly longer. The extent of damage to the kidneys will dictate how long your dog needs to be in the hospital, whether he or she needs further treatment and also their chances of making a full recovery. If the kidney failure is not reversible, putting your dog to sleep may be the kindest option.


Okay so now we are going to move on from grapes to talk about lily poisoning in cats. Domestic cats are the only animals that have so far been reported to be susceptible to lily poisoning with no reports of poisoning in dogs at the time of this podcast. It is thought that all species of lily are poisonous to cats including Easter lily and Tiger lily as well as day lilies. Also all parts of the plants including the flowers and the pollen are poisonous to cats. Most cats are poisoned by ingesting lily plants kept in the home, and even very small amounts can cause serious problems. It is worth specifically mentioning the pollen as it can drop on the floor very easily and may then get onto the cat’s paws and then be licked off. Cat owners beware – please do not keep lilies in the house! Yes, they are beautiful plants but it really is not a risk worth taking!

Lilies cause injury to the kidneys in cats and in the worst cases kidney failure may occur. At the moment it is not known exactly how or why this happens. Although lilies can also cause other problems in cats, kidney failure really is the main one. Cats may start showing signs of being unwell very quickly after eating the plant, even within 10 minutes. They may vomit, drool and appear lethargic or depressed. They will lose their appetite and as time goes by become more and more dehydrated as kidney failure sets in over one to two days.

As with grapes, raisins and currant poisoning in dogs, we would strongly recommend that any cat that is thought to have eaten some lily plant is seen by a vet as soon as possible. If the cat is not already vomiting, this may need to be induced or your vet may want to wash out your cat’s stomach under a general anaesthetic.

Your vet is likely to run some blood and urine tests to check for signs of dehydration and kidney failure. In many cases it may be appropriate for your cat to be admitted to the practice to receive a fluid drip into a vein for 2 to 3 days or possibly longer. The extent of damage to the kidneys will dictate how long your cat needs to be in the hospital, whether he or she needs further treatment and also their chances of making a full recovery. If the kidney failure is not reversible, putting your dog to sleep may be the kindest option.


Okay so now we move on to chocolate, yes delicious lovely chocolate. It might surprise you given the amount of chocolate some people seem able to put away but chocolate poisoning can occur in humans – admittedly this is very rare and aren’t we thankful for that! However chocolate poisoning is not so rare in domestic pets. These species are more vulnerable because they metabolise chocolate much more slowly than people do.

Unsurprisingly cases of chocolate poisoning are more common in dogs and also tend to occur more commonly at certain times of the year for example Christmas, Easter, birthday parties or other times of the year when chocolates and chocolate cake are more likely to be in the house. In many cases the dog will also have consumed some of the paper in which the chocolate may be wrapped, although the wrappers are usually of much less concern than the chocolate itself.
It is worth saying that so-called chocolates or chocolate drops that are specially made for animals are safe because they are not made from cacao beans and do not contain the poisonous substance found in human chocolate.

So what is the poisonous substance contained in chocolate? Well, chocolate is made from cacao beans and contains a substance called theobromine. This substance is very similar to caffeine and in fact chocolate also contains a smaller amount of caffeine as well. Not all types of chocolate are created equally as far as the risk of causing poisoning is concerned. The risk depends on the amount of theobromine the particular chocolate contains and is greatest for plain or dark chocolate as well as cocoa powder. Milk chocolate is the next most dangerous and finally white chocolate is the safest.

The main problem with chocolate in dogs and cats is that it causes widespread stimulation in the body including of the brain, the heart, breathing and the muscles. Your pet is likely to start showing signs within 24 hours of eating the chocolate but it is often much sooner than that and these signs could go on for two to three days. They include vomiting and pain in the stomach area, the abdomen. Poisoned animals may become very excitable, wobbly when walking, and start to pant or breathe quickly. In the most severe cases your pet may start to show twitching and tremoring of the muscles as well as to have fits or to seizure. Some dogs will seem to want to drink more water and to pass more urine.

When you contact your vet, as we discussed in the first of these blogs, it is important to try and give them as much information as possible.  So for example how much chocolate or cake has gone missing and also what type of chocolate is it.

In terms of treatment for chocolate poisoning, it may be appropriate to make animals vomit if they are not already vomiting. We have to be careful here to remember that there are some situations in which making a pet vomit is not a sensible idea, for example if the animal is seizuring or overly excited as can occur with chocolate poisoning. Precautions as far as making animals vomit were discussed in the first of these blogs and you should always contact your veterinary practice for advice before deciding to administer any kind of medications or treatments to your pet.

When your vet sees your pet they may want to run blood tests and especially to perform what we call an electrocardiogram or ECG. This is to look at your pet’s heart rhythm because it is common for chocolate to cause fast heart rates and an abnormal heart rhythm. Your vet will advise you whether they think this is necessary or not based on their examination of your pet.

There is no specific treatment for chocolate poisoning and patients will receive supportive care based on how severely affected they are. This may include being admitted for a fluid drip into a vein, and for medications such as something to stop them vomiting or a sedative if they are very excitable. Your vet may also have to give your pet something to treat an abnormal heart rhythm.
Finally your pet may need to be given some activated charcoal which as we discussed earlier is intended to mop up any chocolate left in the stomach or intestines.

Many patients with chocolate poisoning make a full recovery as long as they can be supported for long enough. However chocolate poisoning can be very serious and regrettably is fatal in some cases. You must therefore be careful not to allow your pets to eat chocolate although we realise that sometimes this is easier said than done – young dogs in particular are amazing at helping themselves to chocolate delights! Most of the cases we have seen seem to have been young Labradors or Boxers!

Anticoagulant rodenticide

Okay so the last type of poison we are going to discuss in this podcast is rat or mouse poison. However not all types of rat or mouse poison are the same and we are going to discuss the type that can cause problems with blood clotting leading to bleeding and bruising. This type of poisoning has been recognised in pets for a long time and can be caused by many different products available from various supermarkets, garden centres and so on. The different types can vary in terms of how long they cause a problem for but they all basically cause the same problem which is bleeding. Without going into too much detail, this bleeding occurs because these poisons prevent the blood from clotting properly; they do this by interfering with vitamin K in the body – vitamin K is essential for blood to clot properly.

As is often the case, problems with rat poison are seen much more commonly in dogs than in cats and it is worth pointing out that although most cases occur when the dog directly eats the rat poison, there have been cases where a problem has occurred after a dog – or indeed a cat – ate a rat or a mouse that had been poisoned; this is because the poison can remain active in the dead rat or mouse for quite a long period of time.

So what signs might you expect to see in a dog suffering from this type of poisoning? Well the first thing to say is that these signs usually take some time to come on, typically at least 2 days and potentially as long as 7 days. It is very important to bear this in mind when you are answering questions your practice asks you – for example was your dog off the lead earlier in the week in the park or did you put down rat poison in the shed a few days ago?

The typical picture we expect to see is that of a bleeding dog although the area in which they are bleeding can vary. Some dogs have breathing difficulties or coughing because of bleeding into the chest or lungs. Others may show bleeding from the nose or the gums or in their faeces. The signs can vary but the basic problem is the same, unexplained bleeding. If the bleeding is severe enough or goes on for long enough, your dog will start to look pale in their gums and can go into shock.

The treatment of this type of poisoning can be quite complicated as it depends on when your dog ate the poison, how severely affected he or she is, and whether the specific type of rat or mouse poison in question is known. Make sure if you know that you tell your vet the name of the product, including the name of the active ingredient, written on the packaging.

If it has only been a few hours since your dog ate the rat poison, then it may be appropriate to make him or her vomit. However this is not indicated once it has been a few hours since ingestion. Your vet may want to do blood tests to check how well your dog’s blood is clotting and these may need to be repeated several times during the course of treatment. They may also want to do blood tests to look for evidence of significant blood loss and in severe cases your dog may need a fluid drip into a vein and potentially a blood transfusion.

Thankfully this type of poisoning is one for which an antidote or specific treatment does exist. Because rat poison prevents vitamin K in the body from working properly as mentioned before, it is possible to treat these dogs with vitamin K. Depending on the individual dog this may be given by injection first but then continued as tablets and this treatment may need to go on for several weeks. Again your vet will discuss this with you. Vitamin K treatment takes some time to start working. Some of the more severely affected dogs therefore need a plasma transfusion to help their blood to clot properly while we are waiting for the vitamin K to take effect.

As we say the treatment of dogs affected by rat poison can be quite complicated but your vet will explain everything to you should your dog be one of the unlucky ones to be affected. Many dogs that suffer this type of poisoning go on to make a full recovery. However this does depend very much on whether they can receive the necessary care that they require, including as we say in some cases blood and plasma transfusions. The outlook also depends on where the bleeding is occurring as some sites in the body can cause more problems than others. Finally just to stress again that vitamin K treatment may need to continue for a period of several weeks so be prepared!

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 consider pyrethrins and pyrethroids contained in some anti-flea products, metaldehyde contained in snail bait or slug pellets, antifreeze, non-steroidal anti-inflammatory medications such as ibuprofen, and paracetamol or acetaminophen. Before we sign off just to remind you that we would really love to hear your comments on this blog as well as suggestions for future blogs relating to emergencies in dogs and cats. 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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