Introduction

A lot of owners are opting for home-cooked food or raw food diets for their animals. Supplementations have also increased with many owners unaware of the potential danger involved. Many items that are relatively safe to humans can be toxic to animals, including food and beverages that are ingested daily by humans. International data showed that most household toxins are ingested (80–85%) vs. cutaneous exposure that accounted for 10–15% of cases. The most commonly listed intoxications were pesticides, followed by rodenticides, plants, drugs and then food. This presentation will focus on foods that are toxic to dogs and cats, including the toxic dose where known. Fortunately very few of these toxins are cumulative. Therapy is often supportive and prognosis for the majority is usually good.

Alcohol

Animals will drink a variety of alcohols. They may also ingest unbaked bread dough, which is also a source of alcohol. When bread dough is ingested, the animal's body heat causes the dough to rise in the stomach. Alcohol is produced during the rising process and the dough expands. Clinical signs include abdominal pain, bloating, ataxia, depression and coma. Clinical signs should resolve without any treatment. If a large amount was ingested, then intravenous fluids with dextrose will be necessary.

Avocado

Certain varieties (mostly from the Guatemala/Mexico strains) contain a toxin called persin. Dogs and cats are far less susceptible to the toxin. Birds are the biggest concern. Leaves are considered the most toxic, causing myocardial degeneration. It can also cause a sterile mastitis in lactating animals. In dogs, the most common problem is gastric obstruction from the seed.

Antifreeze

Antifreeze is found in radiators and is used both as a coolant and for freezing. So, although seen more often in colder climates, toxicities can also occur in areas with warm weather. Ethylene glycol is sweet tasting. It is fatal and only a teaspoon and tablespoon is needed for a cat and dog, respectively. Clinical signs include vomiting, PU/ PD, anorexia, lethargy, coma and seizures.

Prognosis can be good if treated within 8 hours; otherwise, it is guarded to poor. Treatment includes giving vodka IV. This can be done:

1.  As a 20% solution, give 5.5 mL/kg IV q4h for five treatments, then q6h for four additional treatments; dosed as a CRI over 1 hour, or

2.  As a 7% ethanol solution (see Compatibility/Compounding Considerations below) and give 8.6 mL/kg slowly IV followed by a CRI of 1.43 mL/kg/h for at least 36 h, although 48 h is probably better.

Beetroot

Not toxic but does cause red urine, which can be alarming to owners.

Broccoli

There has been a bit of confusion where broccoli is concerned. Broccoli is very good for dogs; however, if the daily intake exceeds more than 10% of the animal's diet, problems can occur. Signs seen include gastrointestinal irritation.

Cannabis, Marijuana and Hashish

The minimum toxic dose is 3 mg/kg for dogs (or 50–100 mg/kg of weight of the plant). No mortalities have been reported, but morbidity is 100%. Onset of clinical signs (within 1–3 hours) is rapid after ingestion or inhalation of the drugs. Clinical signs include weakness, lethargy, ataxia, dilated pupils, nystagmus and photophobia. Some pets also seem to be hyperaesthetic with aggression and barking. One study showed that 60% of cases present with depression, and only 5% with excitement and less than 1% with aggression. Treatment is supportive - emetics and administration of adsorbents (activated charcoal). If the animal is very agitated, then diazepam can be given. Recovery occurs within 24–72 hours.

Chocolates and Caffeine

Caffeine and theobromine (found in chocolates) have an effect on animals similar to that on people. They cause tachypnoea, tachycardia, sometimes even causing arrhythmias. Other signs seen include vomiting, diarrhoea, PU/PD and hyperactivity. Treatment includes intravenous fluids to prevent dehydration and to induce urine production. Symptomatic treatment is given for tachycardia, hyperthermia and seizures. Urinary catheterization may be necessary to prevent reabsorption of the toxin. Symptoms occur with the ingestion of 85 mg per kilogram of body weight. Theobromine deaths have been reported after ingestion of 100 mg per kilogram of body weight. Caffeine is toxic at about 130 mg per kilogram of body weight. Unsweetened baking chocolate contains almost seven times more theobromine than milk chocolate.

Eggs

Cooked eggs can be a healthy treat for dogs, but raw egg whites contain a protein called avidin. This protein depletes an animal of B vitamins, specifically biotin, which is essential to growth and coat condition. Also, raw eggs may contain bacteria, such as Salmonella.

Fruit

Apples, Apricots, Cherries, Peaches and Plums

These five fruits aren't usually thought of as toxic foods. However, they contain a type of cyanide compound that can poison animals if they eat enough of the stems, seeds and leaves. Need to eat quite a bit before it is toxic. Clinical signs include mydriasis, dyspnoea, hyperventilation, shock, and apprehensiveness. Seeds may also cause GIT obstruction.

Grapes

There are now several reports of dogs developing acute renal failure after ingesting grapes or raisins. The toxic substance in this fruit is presently unknown, but is thought to be due to an unknown compound in the "fleshy" part of the grape. There have been no problems reported with grape seed extract. The toxic dose is not known, but signs have been reported with as little as 14 grams grapes/kg bodyweight and 4 grams raisins/kg bodyweight, but most reports include large quantities of grapes and raisins. Currently, the consensus is 40 grams of fresh grapes or 120 grams sultanas or 60 grams raisins is toxic for a 20-kg animal. The toxin causes renal failure, and signs include vomiting, diarrhoea, lack of appetite, lethargy, or abdominal pain. Renal failure does not develop in all dogs that ingest grapes or raisins, but precautionary measures such as inducing emesis, administration of activated charcoal, and initiating fluid diuresis should be considered. The prognosis for recovery is fair to good; the renal injury appears to be fully reversible, and survival is primarily dependent on the availability of adequate medical support. Severe ingestions can be fatal.

Hops

Severe hyperthermia (> 42°C) in dogs has been described after the ingestion of "raw" or "spent" hops (Humulus lupulus). Diagnosis is made by seeing hops in the vomitus of the patient. Clinical signs other than hyperthermia include excessive salivation, vomiting, abdominal tenderness, panting and weakness. Treatment is focused on lowering the temperature - intravenous fluids, rectal enemas, cool wraps, fans and isopropyl alcohol.

Liver

In small amounts, liver can be good for dogs (less than 3 servings a week). Large amounts cause vitamin A toxicity (hypervitaminosis A). Never feed liver if the animal is taking vitamin A supplements, and always cook it before feeding. Clinical signs seen are bone problems, weight loss and anorexia. Discontinuation of feeding liver is usually sufficient as treatment.

Macadamia Nuts

The toxin in macadamia nuts is unknown, but a dose of 0.7–5 grams/kg body weight has been shown to be toxic (roughly 5–40 nuts per 20-kg dog). This includes both raw and roasted macadamia nuts. Symptoms usually start within 3–12 hours of ingesting the nuts and tend to resolve over 24 hours. Lethargy, vomiting, and fever are initial symptoms with progression to ataxia or hindlimb paresis. Also seen are tremors, abdominal pain, lameness, joint stiffness, and pale mucous membranes. Treatment includes: induction of vomiting; gastric lavage is performed; and activated charcoal administered, especially if the macadamia nuts were covered with chocolate. Intravenous fluids are administered to prevent dehydration. Monitor and treat for hyperthermia.

Medications

Pets can ingest a variety of drugs belonging to other pets or owners in the household. Treatment will depend on the drug ingested. Most often gastric decontamination and supportive therapy are needed. The local poison centre or medical drug formulary can be consulted for details regarding each medication.

Milk and Milk Products

Fifty percent of dogs are lactose intolerant (just like people!). They don't produce the enzyme lactase; therefore, they are unable to break down lactose (milk sugar). Animals are often gassy, may have diarrhoea and abdominal discomfort. No treatment is usually necessary.

Moth Balls

Moth balls contain either naphthalene or paradichlorobenzene. Naphthalene is about twice as toxic as paradichlorobenzene. Ingestion stimulates the central nervous system, causing excitement and seizures. Other signs seen include icterus, vomiting and Heinz body anaemia. Toxic dose for a 10-kg dog is only 1.5 mothballs (if they contain naphthalene). Treatment includes gastric lavage, activated charcoal, intravenous fluids and supportive therapy for seizures and methaemoglobinaemia.

Mushrooms

Mushrooms including Amanita phalloides (death angel), A. virosa (destroying angel), A. muscaria (fly agaric), some Boletus spp., Chlorophyllum molybdites (backyard mushrooms), some Clitocybe spp., Cortinarius spp., Galerina spp., Gyromitra spp. (false morels), Inocybe spp., and some Psilocybe spp. ('magic mushroom'). The toxin and dose in mushrooms vary with each species. Clinical signs are seen within 6–8 hours following ingestion. Clinical signs reported include ataxia, depression, coma, nausea, vomiting, diarrhoea, hallucinations, hyperthermia, tearing, urination, drooling, defecation, seizures, liver failure, kidney failure, and death. Treatment is supportive. Liver and kidney function should be monitored.

Mycotoxins

Mycotoxins are produced as the result of fungal metabolism (e.g., mould). Mould is frequently found in garbage and compost heaps. Dogs are more affected than cats. Penitrem A and roquefortine are the most commonly found associated with spoiled and mouldy foods, compost and grains. They affect the central nervous system, causing severe muscle tremors, hyperactivity, panting, irritability, weakness and seizures. Lethal doses are not reported, but a dose of 0.175 mg/kg is considered toxic. Treatment includes emesis and activated charcoal. Diazepam and phenobarbitone can be used in patients that have seizures or severe muscle tremors. Muscle relaxants such as methocarbamol and guaifenesin may be beneficial. Prognosis is good when decontamination occurs early; it is guarded when clinical signs are already present.

Aflatoxin

Mouldy food - especially on dry food. Mycotoxin involved includes Aspergillus flavus and Aspergillus parasiticus. Aflatoxin is called the most carcinogenic substance known, and patients that survive the acute episode may develop liver cancer at a later stage. Acutely, patients present with acute hepatic necrosis. Clinical signs include icterus, vomiting, anorexia, lethargy, oedema, bleeding and coma. Treatment is supportive with IV fluids, antibiotics, antiemetics and lactulose. Vitamin K and plasma should be considered if liver failure is severe. SAMe, N-acetyl cysteine and ursodeoxycholic acid can also be added.

Nutmeg

Nutmeg contains a narcotic called myristicin. It is hallucinogenic in dogs, but not much more is known or reported about it. There are some reports of large dosages of nutmeg being fatal in dogs. A full teaspoon of grounded nutmeg or 1–3 whole nutmegs are reported to cause toxic effects. Clinical signs include tremors, muscle spasms, seizures, hallucinations, nausea, vomiting and death.

Onion and Garlic

Onions, garlic, chives and leeks (Allium spp.) all contain sulfoxide and disulfide compounds. These compounds can cause oxidative damage to erythrocyte membranes leading to methaemoglobin and Heinz body anaemia. Toxicity varies with type and amount ingested. Fresh, dried, raw, cooked or crushed have all been shown to be potentially toxic. Cats are more sensitive than dogs. The toxic doses reported vary greatly, but as little as 2 slices a week can cause clinical signs. Signs include vomiting, diarrhoea, anaemia, discoloured urine, weakness, liver damage, allergic reactions, asthmatic attacks, and in case of skin exposure, contact dermatitis. If dermal exposure has occurred, the animal should be bathed and dried thoroughly. Aggressive use of IV fluids and blood transfusions should be considered. Vitamin E may help to stabilise membrane architecture.

Oxygen Absorbers

These are found in food packets - especially in beef jerky and dried fruit. Oxygen absorbers are used to prolong the shelf life of food. Oxygen absorbers are made in different formulations to match the water activity of the foods they are protecting. In most formulations, the active ingredient is powdered iron or iron salts (50–70% total iron in packaging). Snail bait can also contain iron but at much lower levels than reported in oxygen absorber packets. Ingesting these packets can lead to severe and sometimes fatal iron toxicity, although there appear to be conflicting reports in the literature. We had one case this year that died a week after presentation from severe gastroenteritis and liver toxicity. Iron erodes the mucosal barrier of the stomach, leading to severe haemorrhagic gastritis. In humans, 20 mg/kg of elemental iron is toxic to the stomach, and 60 mg/kg is toxic to the liver. Measuring serum iron levels and liver enzymes can be helpful. Chelation therapy (deferoxamine) can be used if levels are elevated.

Potato

Cooked and mashed potatoes are not toxic. However, poisonous alkaloids (Solanum) are present in green sprouts and green potato skins. Solanine is also found in other plants, which include the deadly nightshade (Atropa belladonna), henbane (Hyoscyamus niger) and tobacco (Nicotiana) as well as the eggplant and tomato. Clinical signs include diarrhoea, abdominal pain, and in severe cases coma and death. Treatment is supportive.

Paintballs

Reports of intoxications are rising as the sport becomes more popular. Paintballs contain polyethylene glycol, glycerol, gelatin, sorbitol, mineral oil and dye. Toxic dose is not known, but one report showed that 15 paintballs ingested by a 40-kg Labrador was toxic. The mechanism is unknown. One theory is that the animal loses hypotonic fluid, leading to metabolic acidosis and hypernatraemia. Clinical signs include vomiting, ataxia, diarrhoea and tremors. The vomit and diarrhoea may be discoloured due to the dye in the paintballs. Other reported signs are tachycardia, weakness, hyperactivity, polydipsia, blindness, seizures and coma. Most commonly seen on tests are hypernatraemia and hypokalaemia. Radiographs may also help with the diagnosis - paintballs are visible on x-rays. Treatment: gastric lavage, IV fluids with 0.45% NaCl with 2.5% dextrose.

Playdough

Causes salt toxicity. As little as 1.9 grams/kg can cause clinical signs. Clinical signs include vomiting, diarrhoea, tremors, seizures, coma and even death. Seizures usually occur when blood sodium levels are > 180 mEq/l. Treatment includes gastric lavage and IV fluids (0.45% NaCl with 2.5% dextrose).

Raw Food Diets

These diets have become very popular. Salmonella is a potential threat. A reputable source for the meat should be used to try to minimise the risk.

Rhubarb

This plant (especially the leaves) contains oxalates which can cause bladder stones and acute renal failure. Clinical signs include anorexia, vomiting, PU/PD and lethargy. Treatment is supportive and includes aggressive intravenous fluid therapy.

Salt

Need to ingest a large amount. Mainly electrolyte abnormalities are seen - hypernatraemia. Clinical signs include tremors, seizures and coma. Treatment: IV fluids with 0.45% NaCl with 2.5% dextrose.

Silica Gel Packets

Silica gel is used to absorb moisture in medication, food and other packaging. Ingestion can cause nausea, vomiting and inappetence. Treatment is supportive.

Tobacco

Nicotine is toxic to animals, but fortunately most animals do not like the taste of tobacco. The toxic dose of nicotine is 20–100 mg. The following table indicates the amount of nicotine in the different tobacco products.

Clinical signs seen include muscle tremors, hallucinations, excitement, tachypnoea, salivation, vomiting and diarrhoea. Animals can also seizure. Treatment focuses on decontamination - stomach lavage and activated charcoal. Intravenous fluids and sedation may be required depending on severity of clinical signs. Do not use antacids as stomach acid inhibits nicotine absorption. Recovery is usually within 12–24 hours.

Tomato

Stems and leaves contain oxalates, which can cause bladder stones and acute renal failure. The fruit itself is not the culprit; however, high amounts of vitamin C can cause gastrointestinal distress. Clinical signs include anorexia, vomiting, PU/PD and lethargy. Treatment is supportive and includes aggressive IV fluid therapy.

Xylitol

Xylitol is used in sugar-free products (gum, mints, oral rinses, vitamins and cooking oil) and is considered safe in humans. Xylitol is specifically popular in diabetics, as it does not require insulin to enter cells. Small amounts can be toxic to animals. Xylitol in dogs causes insulin release up to 6 times greater than an equal dose of glucose. Toxic dose has been shown to be as low as 0.1 g/kg. A stick of gum has 0.3 g and a cup of granulated xylitol has about 190 g. Absorption is quick, and clinical signs can be seen within 15 minutes after ingestion. Clinical signs are due to severe hypoglycaemia (weakness, depression, ataxia, tremors, seizures and coma). Acute liver toxicity has also been reported at dosages as low as 0.5 mg/kg. Treatment with dextrose-containing fluids is indicated. Activated charcoal does not reliably bind to xylitol. Liver protectants and antioxidants (N-acetylcysteine and S-adenosylmethionine) have also been used.

References

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3.  DeClementi C. Moth repellent toxicosis. Vet Med. 2005;100(1):24–28.

4.  Gwaltney-Brant S. Chocolate intoxication. Vet Med. 2001;96(2):108–111.

5.  Thrall MA, Grauer GF, Dial SM. Antifreeze poisoning. In: Bonagura JD, ed. Kirk's Current Veterinary Therapy XII. Philadelphia, PA: WB Saunders; 1995:232–237.

6.  Duncan KL. Malignant hyperthermia-like reaction secondary to ingestion of hops in five dogs. J Am Vet Med Assoc. 1997;210(1):51–54.

7.  Eubig PA. Acute renal failure in dogs after ingestion of grapes or raisins: a retrospective evaluation of 43 dogs (1992–2002). J Vet Intern Med. 2005;19:663–674.

8.  Porterpan B. Raisons and grapes: potentially lethal treats for dogs. Vet Med. 2005;100(5):346–350.

9.  Gwaltney-Brant SM. Macadamia nuts. In: Peterson ME, Talcott PA, eds. Small Animal Toxicology. Elsevier Inc; 2006:817–821.

10. Volmer PA. "Recreational" drugs. In: Peterson ME, Talcott PA, eds. Small Animal Toxicology. Elsevier Inc.; 2006:273–311.

11. Piscitelli C, Dunaver E, Aumann M. Xylitol toxicity in dogs. Comp Cont Ed Pract Vet. 2010;32(2):1–4.

12. Brutlag AG, Flint CT, Puschner B. Iron intoxication in a dog consequent to the ingestion of oxygen absorber sachets in pet treat packaging. J Med Tox. 2012;1:76–79.