Vet In Harness's blog

'C is for Chocolate' - A to Z of Pet Poisons

Quick Facts:

• Poison(s):  Chocolate contains the methylxanthine substance theobromine.  Related methylxanthines are caffeine and theophylline (found in coffee and tea).  Pharmaceutical xanthine preparations are available and are used primarily as bronchodilators (to widen the airways) in conditions including asthma.  They also have uses in cardiovascular disease and the treatment of age related dementia.  Preparations include 'Millophiline', 'Corvental' and 'Vivitonin'.  Methylxanthines have a stimulant action on the central nervous system, cardiovascular and respiratory systems, causing increased alertness, and increasing blood pressure, cardiac output and breathing rate.  So-called 'Dog Chocolates' do not contain cocoa solids or theobromine.
• Species affected: Many animals are sensitive to theobromine and consequently chocolate poisoning can affect most species.  Dogs are particularly likely to suffer accidental poisoning by scavenging or well-intentioned but misguided 'treating' with chocolate-containing items.
• Toxic dose:  the amount of chocolate required to produce a toxic effect in any given patient depends on the size of the patient and the theobromine content of the chocolate.  Theobromine content is estimated from percentage cocoa solids - dark or bittersweet chocolate will have a much higher theobromine content than milk chocolate, continental chocolate also tends to be higher in cocoa solids and consequently theobromine dose.  The more the cocoa content is 'diluted', the lower the potential toxicity.  Consequently, a very small number of squares of dark chocolate has the potential to be dangerous in a small terrier, whereas a large labrador can probably eat several portions of milk chocolate-containing desert without ill effect.
• Symptoms:  The stimulant effects of theobromine are responsible for the symptoms of chocolate intoxication. Affected animals may have increased heart rate and blood pressure and increased breathing rate.  Effects may also be seen from central nervous system stimulation.  This may produce tremors, twitching / nervousness, or in more severe cases seizures, loss of consciousness, and death.  These symptoms may occur within hours of ingestion.  Chocolate consumption can cause gastrointestinal upset.  The fat content of (particularly milk) chocolate products can also cause pancreatitis (inflammation of the pancreas) which causes stomach pain, vomiting and diarrhoea, may be severe, and which will often require hospitalisation and intensive treatment.  Gastrointestinal symptoms will often take a day or more to become apparent.
• Action:  Contact your veterinary surgery for advice immediately if you believe your pet has consumed chocolate or chocolate-containing foods, even if they are not showing any unusual symptoms at the time.   It will be helpful to your vet if you are able to provide them with the weight of the animal, the exact chocolate / foodstuff consumed, how much has been eaten, and the time that has passed since the substance was eaten (or if you do not know this precisely, for instance the box of chocolates disappeared from the coffee table while you were out of the house, the earliest and latest times that it could have occurred).  If your pet is showing any symptoms, it is important to seek immediate veterinary attention - but do call ahead so that the surgery can make arrangements to see you as quickly as possible.
• Treatment:  Your veterinary surgeon will attempt to estimate the total dose consumed from the information you are able to give them, and will assess whether treatment is likely to be required. They may consult a poisons information service for specialist advice.  The more complete the information you can provide, the more accurate this assessment will be and unnecessary treatment may be avoided - if information is incomplete, precautionary treatment may be advised.  If treatment is considered necessary, it may include induction of emesis (making the animal sick) or gastric lavage ('stomach pumping') if the chocolate has been consumed reasonably recently.  Further treatment  may include administration of intravenous fluids (a drip) to support the circulation, and activated charcoal to absorb theobromine from the digestive tract.  Treatment may also be required for pancreatitis or more mild digestive upset, should these arise.  While deaths do sometimes occur from chocolate poisoning, most cases, if seen promptly, can be treated successfully.  

Perhaps fortunately, the sort of milk chocolate popular in the UK is very low in cocoa solids, so cases of serious poisoning from Dairy Milk and Mars bars are uncommon in all but the smallest dogs.  Don't however underestimate the cocoa content of cakes and deserts prepared with cocoa powder.  If in doubt, it's always better to seek advice early than to wait and see.  

Chocolate poisoning is an unfortunate feature of the holiday seasons in veterinary practice - we see it most commonly around Christmas and Easter, though of course it can occur at any time of year.  Please be careful when leaving chocolates around the house - particular in larger than usual seasonal quantities - and avoid the use of chocolate Christmas tree decorations (which are usually pretty disappointing in any case!).  Please also beware the alcohol content of liqueur chocolates.  Sadly, poisoning of pets by intentional 'treating' with chocolate does still occur, so continuing education of both the pet owning and general public is clearly required.

A to Z of Pet Poisons - Index

'B is for Barbiturates' - A to Z of Pet Poisons

 

Phenobarbital

Quick facts:

• Poison(s): Drugs of the barbiturate class.  This group of drugs is used in human and veterinary medicine for anaesthesia, sedation, the relief of anxiety and insomnia, and prevention of seizures (fits).  Barbiturates form part of some 'lethal injection' cocktails used by the US penal system, and are also used in veterinary medicine for humane euthanasia of patients.  Barbiturates have abuse potential.
• Species affected:  All species, dogs are most likely to suffer accidental poisoning.
• Toxic dose:  Depends on the drug, route of administration, and the patient.  Any accidental barbiturate ingestion or overdose in an animal or a human is potentially serious.
• Symptoms:  Barbiturates are sedatives. Initial symptoms include weakness and sleepiness.  Low blood pressure and reduced breathing rate will develop, and depending on dose, may be followed by unconsciousness, coma, and death.
• Action:  Contact your veterinary surgeon as soon as possible if you believe your pet may have been exposed to any barbiturate.  In general accidental ingestion of any prescription, non-prescription, or 'recreational' drug may be extremely dangerous, and you should seek advice as soon as possible if you believe your pet may have been exposed to them.  It will be helpful to your veterinary surgeon and to poison control / advice services if you have the name of the drug, strength, and quantity to hand, as well as knowing the weight of your pet.
• Treatment:  Will depend on the drug, the dose to which the pet has been exposed, and the severity of symptoms at the time of presentation.  There is no specific antidote to barbiturate poisoning / overdose and treatment is focused on supporting the patient while the drug is cleared by their body.  Treatment may include gastric lavage (stomach pumping), giving supplemental oxygen or artificial respiration if breathing is severely compromised, intravenous fluids to support the circulation, and drugs to encourage the heart to beat more strongly.  Despite intensive management, if a sufficiently large dose of drug has been absorbed, barbiturate overdose is commonly fatal.

Barbiturates have become less commonly prescribed in human medicine over the past few decades because of the potential for abuse, and the very narrow margin between the dose required for a 'high' and that which will induce a fatal coma.  Safer drugs are now available for the treatment of anxiety and insomnia.  Barbiturates remain in quite common use in veterinary medicine.  Sodium thiopental is a general anaesthetic agent, though this is less used now than a couple of decades ago.  Pentobarbital is the drug commonly used in the UK for humane euthanasia of veterinary patients.  Phenobarbital (trade names include 'Epiphen') given in tablet form is used to prevent seizures (fits) in epileptic dogs.      

 

Accidental overdosing with medications prescribed for epileptic patients, or dogs deciding to 'scavenge' medications belonging to owners or members of their households are the common routes of exposure.  Rarer, but something which is seen occasionally, is barbiturate overdose in dogs or cats caused by them scavenging and eating remains of animals who had been 'put to sleep' with a barbiturate injection.  Please think carefully about where and how you bury pets' remains, particularly after euthanasia, and consider arranging for cremation if there is nowhere safe or appropriate in your garden to lay your pet to rest.

Next Time - C is for Chocolate -- A to Z of Pet Poisons - Index

 

'A is for Alcohol' - A to Z of Pet Poisons

'He made some hootch and tried it on the dog' by Arthur Burdett Frost, published 1921

Quick facts:

• Poison(s): ethanol (drinking alcohol), isopropyl alcohol (rubbing alcohol), methanol (methylated spirits) 
• Species affected:  Dogs and cats, more common in dogs.
• Toxic dose:  Varies depending on substance ingested and strength of the preparation.  Published LD50 (mean lethal dose, usually derived from studies in rodents) for ethanol is ~10g per kilo of body weight.   Serious toxic effects can be expected well below this dose.  Doses above half a standard unit (or 4g) per kilo of body weight of ethanol are very likely to have severe or even life threatening consequences. LD50 of methanol and isopropyl alcohol are around half that of ethanol.  Lower doses (particularly of isopropyl alcohol and methanol) are also likely to cause serious problems
• Symptoms:  Initially coordination problems, excitement progressing to depression, loss of consciousness, progressing to cardiac and / or respiratory arrest potentially resulting in death.  If inhaled, can cause severe breathing difficulties.  Where skin contact occurs, irritation is possible.  Serious damage to the eyes can occur from splashes of concentrated alcohols.  Methanol also causes liver damage and blindness.
• Action:  Seek veterinary advice as soon as possible if your pet is showing any signs of alcohol poisoning or if you believe they may have ingested or come into contact with any noxious substance.   Small amounts of weak drinking alcohol (eg the dregs in a beer can, or  a small amount of spilled wine) are unlikely to cause a problem and emergency treatment is probably unnecessary, though you should monitor your pet closely for any symptoms and seek advice and treatment if appropriate.
• Treatment:  Will depend on the substance swallowed / inhaled, dose, and severity of symptoms, but may include gastric lavage (stomach pumping), intubation to protect your pet's airway, and drug treatment to control symptoms.

 

Alcohol poisoning is commonly the effect of accidental ingestion of alcoholic drinks by pets.  Dogs are generally more prone to eating and drinking things they shouldn't than cats are.  Sadly, we also see cases of people intentionally feeding animals alcoholic beverages.  While small amounts of alcohol are unlikely to be dangerous, please never give dogs or cats even small amounts of alcohol.  No, Auntie Mabel's Chihuahua does *not* want or need a tot of brandy at Christmas!  And despite the fact a lot of dogs seem to like the taste of beer, please don't buy them a pint when you get your round in at the pub!  

The relative difference in body weight between pets and humans, and differences in metabolism of alcohol, can make even small doses potentially hazardous.  Also consider that the experience of being 'drunk', though some humans might find it pleasant and it may be entertaining to watch, must be very frightening for a pet who doesn't know what is going on!

Don't forget the risks of dogs or cats ingesting significant quantities of alcohol in liqueur chocolates (we'll get on to the hazards of chocolate - and theobromine, which it contains - further down the alphabet), booze-soaked Christmas cake or Christmas pudding (which also contain raisins and currants which are toxic in their own right) or 'cleaning up' human vomit at boozy teenagers' parties!

Next time - B is for Barbiturates. -- A to Z of Pet Poisons - Index