The 12 Hazards of Christmas

Actually there are probably many more, so do your vet a favour and don’t give them a reason to have their holiday disrupted. Here are a dozen to look out for:

1 Weather use of chemicals to thaw ice and snow can cause serious problems for dogs. Automotive anti-freeze, radiator coolant, windshield de-icing agents, motor oils, hydraulic brake fluid, paints and solvents that typically contain ethylene glycol are extremely toxic to dogs (and cats) and even a small quantity can cause renal failure. Dogs are particularly attracted to it because it tastes sweet (cats are not sensitive to sweetness). Clinical signs of poisoning occur between 30 minutes and 12 hours after ingestion and include ataxia, hypersalivation, vomiting, seizures, polyuria and polydipsia. 12-24 hours following exposure, tachypnoea, tachycardia, hyper or hypotension and circulatory shock may develop. Metabolic acidosis with compensatory hyperventilation can also occur. 36-72 hours following ingestion, severe renal impairment sets in resulting in inappetence, lethargy, halitosis, coma, depression, vomiting and seizures. Hypocalcaemia can result in manifestations of tetany.

De-icing gritting salts used on roads and pavements can cause problems as they freeze onto paws and coat, causing ulcers and redness to
tissue which can lead to bacterial infections. Dogs can also develop intestinal problems and gastritis from licking their paws.

2 Plants lots of common garden, park and countryside plants are toxic as are various fungi and fruits such as horse chestnuts. Be particularly aware of dogs who scavenge and may ingest poisonous plant material accidentally and discard waste promptly and securely when trimming hedges and clearing gardens. In addition, house plants and flowers can cause poisoning from contact or ingestion.

Lilies are a particular problem as the toxic pollen can be brushed of and ingested during grooming, although all parts of the plant are poisionous to dogs. Seasonal favourites poinsettias have leaves that contain an irritant sap that can cause nausea and vomiting if ingested. Affected dogs may drool and paw at their mouth. Holly and mistletoe are much more toxic and if ingested can induce vomiting and diarrhoea, excessive drooling and abdominal pain. Mistletoe can induce a sudden and severe drop in blood pressure, breathing problems and hallucinations. Seizures and death may follow. The leaves and berries of holly and mistletoe plants, including dried plants are a potential hazard. Pot pourri is also toxic.

Amaryllis plants contain lycorine and other noxious substances which cause salivation, vomiting, diarrhoea, decreased appetite and abdominal pain, lethargy and tremors. The bulb is more toxic than the flowers and stalk. Take care to pot any plants so that they do not become top-heavy and topple over when they have flowered where they then become accessible to dogs.

Early-flowering bulbs are popular indoors at this time of year and most are toxic. This includes, lilies, daffodils, hyacinths and tulips. Severe hyacinth or tulip poisoning often occurs when dogs dig up freshly planted bulbs or gain access to bulbs waiting to be planted. Typical signs of poisoning include profuse drooling, vomiting and diarrhoea. Consuming large amounts causes tachycardia, tachypnoea and difficulty breathing.

If you want to decorate your home with house plants, the Christmas cactus may be the safest option as it is not toxic, although ingesting large amounts of leaves can cause vomiting or diarrhoea.

The habit of bringing live fir trees into the home that was started in the mid-19thC also introduces the oils produced by fir trees into the home. These are irritating to the mouth and stomach and, if ingested, cause excessive vomiting or drooling. Needles can cause gastrointestinal irritation, obstruction and puncture. Even the water used to keep the tree alive over the holiday can harbour bacteria, moulds and fertilizers which can cause severe illness if drunk.

Much older traditions such as decorating the house with holly, ivy, yew and mistletoe could kill your dog. Holly contains toxic saponins, methylxanthines and cyanogens which produce severe gastrointestinal upset. Affected dogs smack their lips, drool and shake their heads excessively with mechanical injury from the spiny leaves.

Ivy leaves cause gastrointestinal distress, vomiting and diarrhoea when eaten and the sap can induce a skin rash and irritate mucus membranes.

All parts of the yew plant, including the berries, are extremely poisonous. Taxines in the yew cause drooling, vomiting, weakness, difficulty breathing, life-threatening changes in heart rate and blood pressure, dilated pupils, tremors, seizures and eventually coma and death.

Mistletoe ingestion causes drooling, vomiting, diarrhoea, abdominal pain, hypotension, ataxia, collapse, seizures and eventually death.

3 Chocolate or to be more precise, the theobramine that it contains, is one of the most common causes of poisoning in dogs. It has become more serious in recent years as high cocoa solid chocolate has become more prevalent. Dogs metabolise theobromine much more slowly than humans and dogs are likely to be attracted to chocolate because even high cocoa solid chocolate contains sugar. Approximately 0.02 oz/lb (1.3 g/kg) is sufficient to cause symptoms of toxicity. 1 oz of milk chocolate per pound of body weight is a potentially lethal dose in dogs and again, small amounts an cause cumulative problems. Symptoms of theobromine poisoning include nausea, vomiting, diarrhoea and polyuria which can progress to cardiac arrhythmias, epileptic seizures, internal bleeding, heart attacks and eventually death.

4 Dried Fruits although we no longer need to preserve fruits by drying, dried fruits are a popular staple at Christmas, whether presented on their own or in cakes, ice cream and puddings. The toxicity to dogs presented by grapes, raisins and sultanas is a relatively recent phenomenon that was first identified by the Animal Poison Control Centre run by the American Society for the Prevention of Cruelty to Animals. Approximately 140 cases were seen between April 2003 and April 2004. 50 dogs developed symptoms of renal dysfunction and 7 dogs died. The mechanism of toxicity is still not known, although it is thought most likely to be a mycotoxin. Onset of symptoms is
sudden and includes anuria, vomiting and diarrhoea followed by weakness, inappetence, polyuria and abdominal pain. Acute renal failure develops within 48 hours of ingestion. A blood test may reveal increases in blood urea nitrogen (BUN), creatinine, phosphorus and calcium. Many dried fruits such as apricot, apples and pears are preserved using sulphite or potassium sulphite (sulphur dioxide 220, sodium sulphite 221, sodium bisulphite 222, sodium metabisulphite 223, potassium metabisulphite 224, potassium sulphite 225 and potassium bisulphite 228) that liberate sulphur dioxide. Thiamine (Vitamin B1) deficiency can occur when dogs (and cats) ingest sulphite preservatives. Thiamine deficiency causes severe neurological symptoms and can be fatal. Sulphite preservatives are, incidentally, used in some commercial raw pet food products.

5 Onions, Garlic, Leeks, Shallots and Chives There are approximately 200 native, cultivated and ornamental species of allium, all of which can be toxic to dogs. Most commonly, problems are caused by onions (Allium cepa), leeks (Allium porrum), chives (Allium schoenoprasum), shallots (Allium cepa aggregatum) and garlic (Allium sativum). Even though garlic is toxic to dogs, it is used in small amounts, confusingly, therapeutically for its antibiotic, antiseptic, anti-inflammatory and anti-viral properties as well as a flea-deterrent.

It is the organosulphoxides present in the allium species that are toxic. When the plant is chewed, they are converted to a complex mixture of sulphur-containing organic compounds that are absorbed through the gastrointestinal tract and metabolised to form highly reactive oxidants. Cooking, spoilage and ageing do not reduce the potential toxicity. The main effect of the oxidants is to cause oxidative haemolysis, rupture of the cell wall or membrane (lysis) in red blood cells. The death of the red blood cells causes anaemia, methemoglobinaemia and impaired oxygen transportation which may not peak until several days after ingestion. Allicin and ajoene in garlic are potent cardiac and smooth muscle relaxants, vasodilators and hypotensive agents and ajoene and other organosulphur compounds derived from onions are potent antithrombotics. Toxicosis typically ensues after consumption of a single large quantity of allium species or as the cumulative effect of ingesting small amounts repeatedly. Consumption of as little as 15 g/kg of onions can cause toxicosis which has been observed consistently when more than 0.5% of the dog’s body weight has been consumed in one go.

6 Nuts and Sweets All nuts present a risk to dogs as, in sufficient quantities, even those that are not toxic can cause a stomach upset, obstruction or laceration if the shells are chewed and ingested. Almonds and pistachios can cause gastrointestinal distress and even pancreatitis. Walnuts contain tremorgenic mycotoxins that can cause seizures. Macadamia nuts are very rich in fat and can cause gastrointestinal distress and pancreatitis. In addition, macadamia nuts are part of the grape family and may contain an unknown toxin that can cause neurological disruption. Pecans and hickory nuts contain the toxin juglone that can can cause gastrointestinal distress and obstruction. Raw cashews contain the toxin urushiol which is the same toxin that is in poison ivy. Contact with skin provokes severe itching which can lead to the development of open sores and raised red patches that may blister and weep. If ingested, the mouth and throat can become irritated and inflamed and they can cause gastic pain and vomiting.

Many sweets, especially the “gummy” type contain xylitol which can also be found in chewing gum, cakes, mouthwash, human toothpaste and various supplements. It is a potent, cheap sweetener that is increasingly being used as a sugar-substitute. Xylitol is a naturally occurring sugar alcohol that can be found in low concentrations in the fibres of many fruits and vegetables and is extracted from berries, oats, mushrooms, corn husks and sugar cane. The first reports of poisoning in dogs occurred in 2002 but incidents have since increased significantly. Doses greater than 500 – 1000 mg/kg body weight have proved fatal. Just one to two pieces of chewing gum can kill a small dog. Xylitol induces the release of insulin in the body causing hypoglycaemia and liver damage. Hypoglycaemia results in a loss of co-ordination, depression, collapse and seizures in as little as 30 minutes. Other signs can be rapid or delayed and include vomiting, lethargy, convulsions, coma and death.

7 Cheese whilst cheese is used as a treat by many owners, it can cause problems for dogs. Roquefort and other blue cheeses contain roquefortine C which is produced by the fungus that gives the cheese is characteristic veining. Roquefortine intoxication is characterised by vomiting, panting, muscle tremors, paddling, hyperaesthesia and seizures. Many cheeses have high levels of salt and lactose. Puppies possess abundant quantities of the enzyme lactase prior to weaning to enable them to digest their mother’s milk but adult dogs lack sufficient lactase to digest milk and milk products well and thus can show the same signs of lactose intolerance as some humans – upset stomach and diarrhoea.

8 Rubbish you may have noticed that dogs do not possess a sense of disgust, in fact they positively revel in tipping out bins however noisome. Unfortunately, moulds and other toxins produced by the decomposition of foodstuffs as well as objects that can cause mechanical injury result in many dogs becoming ill and injured over the holiday period. Mycotoxicosis can result in polypnea, tachycardia and ataxia. Prognosis will vary according to the type of toxin ingested. Dogs have evolved to swallow food quickly and regurgitate anything
that does not agree with them. If you see your dog about to eat something that he shouldn’t approach calmly; shouting and chasing is more likely to make him gulp it down and possibly injure himself, including if it makes him vomit. Contact a vet immediately of you think that your dog has swallowed something dangerous.

9 Alcohol it is hard to believe, but some people deliberately give their dogs alcohol, although it is at best unpleasant for the dog and at worst can be fatal. As with chocolate, alcohol makes dogs more intoxicated more quickly than people. Symptoms vary depending on the amount ingested and whether the dog’s stomach is full or empty. The main symptom is a depressed central nervous system which may develop 15 to 30 minutes after ingestion on an empty stomach and up to two hours later when ingested on a full stomach. Other symptoms include urinating or defecating involuntarily. Higher doses can lead to behavioural changes ranging from depression to excitement, hypothermia, slow reflexes and flatulence. Signs of advanced poisoning include depression, bradypnoea and bradycardia, metabolic acidosis and heart attack. If left untreated, this can be fatal. Alcohol is not only present in drinks but can result from the fermentation of bread dough and rotten fruit as well as being a constituent of some medications. Dogs may be attracted to alcoholic drinks because of the sugar content, especially with sweet drinks such as liqueurs or chocolates containing alcohol.

10 Bones there is no doubt about it, bones can and do cause irreparable harm and death to dogs in spite of owners who swear that they have always fed them. Dogs are not wolves. They have different digestive enzymes and different gut bacteria. Wolves also eat whole animals, hoof, hide and hair, as well as bones. This enables a protective mechanism whereby the hair wraps around bone splnters as they pass through the gut. They are expelled in pellets, rather like those that owls excrete, and so mean that the wolf’s gut is not as
vulnerable to perforation. Dogs cannot do this. There is a bone in the x-ray image on the left that defnitely does not belong to the Bichon Frise.

Raw bones are covered in pathogens and may transmit parasites such as tapeworm; tests have discovered salmonella, shigella, yersonia enterocolitica, echinoccus, e. coli, clostridium perfringens, campylobacter, staphlycocci and mycobacterium bovis on raw bones. Leaving a bone out for a dog to chew on over several days, especially if it is left outdoors, only increases the likelihood that it will be contaminated with life-threatening bacteria. Human health is also at risk, especially in the young, old or immuno-suppressed. Modern farming methods mean that animal bones often lack density, even those raised “organically” and are much more likely to splinter even if not cooked. Feeding raw bones can cause constipation, gastroenteritis, GI obstruction and perforation and septic peritonitis. Bones can break teeth, including the large teeth needed for chewing, and cause painful abscesses. A broken tooth may need to be extracted making it harder for the dog to eat for the rest of its life. Shards that break off while the dog is eating can pierce the tongue, cheek or soft palate or become looped around the lower jaw. Round bones can get stuck around the lower jaw behind the lower canine teeth; most dogs need to be sedated or anaesthetised in order to cut it off. Pieces of bone can lodge in the oesophagus which can be pierced as the dog swallows. It is also possible for a piece of bone to get into the trachea interfering with breathing. Large fragments of bone can get stuck in the stomach requiring abdominal surgery or endoscopy to remove. If the piece of bone is sharp, it can penetrate the stomach wall enabling the stomach contents to leak into the abdomen and causing peritonitis, which can be fatal even if treated. Bones can block the small intestine or the colon also requiring surgery to remove. They can penetrate the intestinal wall and cause peritonitis. Bone fragments may travel far enough down the GI tract to get to the large bowel and colon where they can collect and cause severe constipation. This is extremely painful as the bone fragments scrape the lining of the colon and rectum. Enemas and manipulation are generally required to evacuate the large bowel. The trauma to the colon may cause significant bleeding. Cooked bones are soft and splinter more easily than raw.

Make sure that dogs cannot get to carcasses. Small bones can present a choking hazard to dogs as with as people.

11 Silica Gel, Candles, Batteries and Toys Silica gel is considered biologically inert so when swallowed by a dog should be harmless, although the packaging may not be. However, if a large enough quantity is swallowed, the intestinal tract may be obstructed and if sachets have been in medicine containers, they will have absorbed an element of the drug which is likely to be toxic for a dog. Some moisture absorbing sachets contain reduced iron and, in sufficient quantities, this can be harmful. Be extremely careful when opening packaging and, even if you think that your dog has only ingested silica gel, obtain veterinary advice as soon as possible.

Candles present an obvious danger of injury and fire so should be sited well away from wagging tails and curious noses. Never leave candles unattended. Scented candles may release benzene and toluene into the atmosphere in quantities that are more likely to be harmful for a dog than a person. Even plain paraffin candles can release harmful substahnces when burned. Even though they are not toxic, eating candles is not going to make a dog feel good.

Many modern devices and toys contain batteries that can be within easy reach of dogs. All types of battery are toxic if the casing is punctured. Either alkaline or acidic material is likely to leak causing severe ulceration to exposed tissue. The most common ingestion is of an alkaline dry cell battery or button/disc batteries that are used for remote devices, watches, torches and toys. Alkaline dry cells contain potassium hydroxide or sodium hydroxide which, when in contact with body tissue, causes liquefaction necrosis. Newer types of disc-shaped batteries can enable an electric current to pass to the tissues of the gastrointestinal tract as the battery is ingested and excreted causing current-induced necrosis to the mouth, oesophagus, stomach or small intestine. Lithium button batteries are the most
dangerous: one 3 volt battery can result in severe necrosis within 15-30 minutes of contact. Some batteries contain heavy metals such as mercury, zinc, cobalt, lead, nickel and cadmium. Heavy metal poisoning can result if the battery remains in the gastrointestinal tract for more than 2-3 days. Oral ulcerations may not present until hours after ingestion. Black powdered material may be seen in the mouth if dry cell batteries have been punctured. Vomiting may cause corrosive injury to the oesophagus and oropharynx.

Small toys, whether intended for dogs or humans, can be swallowed and cause serious harm. Similarly, pieces may break off larger toys when chewed. Never leave dogs unsupervised with toys and discard any that are damaged, including any broken pieces. Make sure that balls and other toys are the right size for the dog and cannot get stuck in the throat or be swallowed. Make sure that human toys are not accessible to dogs especially if the dog is not being supervised.

12 Decorations although many decorations may not be made of toxic materials, they can cause injury and harm to dogs. Decorated trees often present baubles and other hangings that are tantalising for dogs especially puppies. Remember, your dog may not be able to distinguish between a glass bauble and his ball. The colours that he sees will not be as distinct as they are for humans and he will have no concept of suddenly seeing lots of apparent dog toys dangling for him to jump at. Do not place decorations at a height where they can be reached easily and never leave a dog unsupervised with a decorated tree that can topple over. Some ornaments may be decorated with toxic paints and glues.

If the tree is being watered, make sure that the dog cannot drink the water as it could contain toxins such as pesticide residues and fertilisers. Do not use aspirin or flower food in the water to keep the tree alive. Fir tree oils can irritate a dog’s mouth and stomach and cause vomiting or drooling if licked, chewed or ingested. Tree needles can obstruct or puncture the gastrointestinal tract so care should be taken to clear up shedding. (Makes a change from dog hair).

Some people hang food from trees, including chocolate. Check the list of toxic foods to make sure that any food is safe.

Make sure that wiring is tucked away where it cannot be chewed or tripped over and that lights are not low enough to be chewed or cause burns if touched.

Tinsel and other strings of decorations can block and damage the intestines causing decreased appetite, vomiting, diarrhoea, lethargy and weight loss. Surgery is often necessary. Pulling tinsel from a tree could cause it to topple over and damage to wiring of lights could spark a fire or present risk of electrocution.

Click here to see just a few x-rays of things that dogs (and other pets) have swallowed.

Have a safe and happy holiday and make sure that those on-call vets can catch up with their reading.

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