Facts and Fiction

Chapter 22


Urban Legends of Toxicology


Facts and Fiction




Tens of thousands of potentially toxic exposures are reported to U.S. animal poison control centers annually. Most of these exposures are not life threatening, and many do not cause harm. Understanding the realistic significance of these exposures depends on knowledge of the animal species, the actual toxicity of the chemical to which the animal was exposed, and the circumstances surrounding the exposure.


All substances must be considered potentially toxic; however, whether clinical toxicity occurs is often simply a matter of whether a dose delivered to the animal is high enough to cause toxicosis. Considerations in formulating a toxicologic risk assessment include (1) the toxic substance and its chemical and physiologic characteristics such as concentration and formulation, (2) characteristics of the animal involved such as species, size, age, sex, and physiologic condition, and (3) the exposure characteristics, which include the route and duration of exposure. Ingestion is by far the most common route of exposure. Therefore, given the numerous chemical and biologic variables involved in any exposure instance, it is unsurprising that not all exposures to toxic substances result in clinical toxicosis. The role of the clinician is to review the specific circumstances surrounding an exposure and offer appropriate judgment and recommendations. Favorable outcomes depend on prompt veterinary intervention following any potentially harmful exposure.


Brand name products often change ingredients through the years, which often alters the hazard. Products with similar names and intended mimicry in names can cause confusion when determining an assessment of relative risk. Therefore it is always important to read the label, determine the ingredients, and be certain that an actual exposure did occur. It is also critical to examine the patient.


All too frequently, however, individuals with emotional concerns and limited chemical and medical knowledge become vocal in news and electronic media—for example, the Internet—in declaring toxic problems inappropriately. These are often blanket statements incriminating products or situations as being the absolute cause of animal illnesses or death. Once these statements become ingrained in the media and are circulated widely, they become urban legends. Such urban legends may be repeatedly presented to veterinary practitioners as inquiries, concerns, or even facts.


The truth is that almost all urban legends are exaggerations of potentially risky situations or misinterpretations of related information that are erroneously applied to everyday events or behaviors. It then becomes the responsibility of veterinarians to apply their knowledge and people skills to clarify these concerns and hopefully place the urban legend in its appropriate category.


The following are a selected number of statements concerning potentially toxic exposure situations that have commonly been reported to veterinarians. In some cases the concerns may be valid, whereas in others evidence of significant risk simply does not exist. Many urban legends are rumors spread through Internet communications. It almost goes without stating to be careful of Internet misinformation. As much as we all appreciate information, to quote former President Ronald Reagan, “Information is good information only if it can be verified.”


Consider how you would respond to the following statements. Are they true, false, or possible? Remember that often it is the combination of variables that ultimately affects the outcome of every chemical exposure!



Home Care and Cleaning Products




• Ingestion of any small desiccant sachet “Fresh-Packet” is harmless to dogs and cats.


    False: These products serve as a desiccant, as the name implies, to control spoilage due to accumulation of moisture and/or oxidation. They may contain silicates (Na2SiO3), activated carbon (charcoal), iron compounds (FeN3O9), or other desiccants. In addition, sometimes the silicate products contain a color indicator (CoCl2) that turns pink when hydrated. Each of these ingredients may irritate the gastric mucosa; the iron-containing packets and color indicator–containing packets can be toxic to dogs and cats.


• Ingestion of Swiffer WetJets kills dogs by liver failure.


    False: This product contains water (80% to 90%), propylene glycol (1% to 4%), isopropyl alcohol (1% to 4%), and preservatives (0.1%). Propylene glycol is much less toxic than ethylene glycol found in antifreeze, and this concentration of propylene glycol taken orally should not present a hazard. If there is a problem following ingestion, most likely a foreign body has been introduced or it is the result of a preexisting condition.


• Ultra Clorox contains lye and therefore is potentially dangerous for your dog.


    False: Both ultra Clorox and regular Clorox bleach formulations contain 5.25% aqueous sodium hypochlorite but not sodium hydroxide (i.e., lye). However, sodium hypochlorite is still corrosive and may cause harm from eye or skin contact, ingestion, or inhalation. It is often used as a good premise disinfectant, but it is best to keep it away from pets.


• Pot-scrubbing sponges contain dangerous amounts of Agent Orange (2,4-D + 2,4,5-T).


    False: Packages of these commercially available sponges are moist inside because a liquid antimicrobial is included to ensure that no fungal growth develops. The antimicrobial agent is a nontoxic disinfectant and even has some perfume added. Now hands will smell nice after “doing pots and pans.” However, if the sponges become grease filled and are ingested, they could lead to gastrointestinal obstruction. It is best to properly dispose of these products following their use.


• Febreze, the odor elimination product, is dangerous for household pets.


    False: Zinc chloride, present in the pre-1998 formulation, was removed, and now the product is sold as a pump spray rather than as an aerosol that could have been an inhalation hazard to some birds in confined spaces. Febreze contains water, alcohol, a corn-derived odor eliminator, and fragrance. Toxicity is not expected with routine use, even with exaggerated exposure.


• Resolve spot and stain carpet cleaner is lethal when ingested by dogs and cats.


    False: This product contains soap, sodium bicarbonate, alcohols 1.5% (ethanol, 2-propanol, and carbinol), glycols 1% (propylene glycol and methyl ether), citrus/pine scent, and water. It is not a lethal formulation. It can cause temporary minor eye irritation and mild gastrointestinal upset if ingested. It is best to keep all household products out of a pet’s reach.



Foods




• Macadamia nuts produce muscle weakness in dogs.


    True: Weakness, depression, and vomiting usually occur 6 or more hours after ingestion of about 1 nut per kilogram of body weight, or more. Weakness and depression gradually improve after 24 hours in dogs without significant preexisting medical conditions.


• Ingestion of grapes and raisins may result in acute renal failure in dogs.


    True: Vomiting, polydipsia, and lethargy can occur 5 to 6 hours after ingestion, followed by anorexia, anuria, tremors, and diarrhea. One to two grapes per kilogram of body weight has been reported as sufficient to induce adverse clinical signs in some dogs. Significant ingestion warrants prompt decontamination (emesis), followed by oral dosing with activated charcoal. In addition, aggressive fluid therapy within 48 hours may prevent acute renal failure from developing. Interestingly, this syndrome has not been reported in cats, and many dogs ingesting grapes or raisins do not develop clinical signs of toxicosis.


• Ingestion of sugarless candy/gum containing xylitol is poisonous to dogs.


    True: Weakness, ataxia, and total collapse may occur 30 to 60 minutes following ingestion of significant amounts of sugarless candy, gum, or breath-mints. Xylitol promotes insulin release by the pancreas, which results in profound hypoglycemia. Absorption is rapid, and activated charcoal is not efficacious in most instances. Acute hypoglycemia is best treated with intravenous dextrose—an initial bolus followed by continuous intravenous drip, with blood glucose concentrations being monitored over the next 12 to 24 hours (see Web Chapter 24).


• Tea is a good poisoning antidote for cats and dogs.


    False: Tea contains 300 to 1200 mg/oz of caffeine, whereas semisweet chocolate contains 22 to 138 mg/oz, making tea on average 5 to 10 times more toxic than chocolate. Tea does have other beneficial actions, but for cats and dogs the bad effects from the high caffeine usually outweigh potential good effects.


• Ingestion of chocolate can poison cats and dogs.


    True: Chocolates contain the methylxanthines caffeine and theobromine, which can be toxic. Unsweetened baking chocolate contains the most methylxanthines (40 and 390 mg/oz for caffeine and theobromine, respectively), and white chocolate has the least (0.8 and 0.2 mg/oz, respectively). The higher the cocoa content of the chocolate, the higher the methylxanthine risk per ounce of chocolate. Hyperactivity, polydipsia, vomiting, diuresis, diarrhea, restlessness, tachycardia, cardiac arrhythmia, and seizures usually occur in a progressive fashion beginning shortly after significant ingestions. Treatment should be directed at decontamination, control of anxiety and seizures, and the support of renal elimination through fluid diuresis.


• Ingestion by dogs of cocoa beans, coca hulls, cola, coffee, and tea leaves may require emergency treatment.


    True: All contain variable but potentially toxic concentrations of methylxanthines (caffeine, theobromine, and theophylline). Depending on the dose ingested, acute vomiting, excitement, cardiac irregularities, tremors, and seizures may result. Treatment includes early digestive tract evacuation plus activated charcoal/cathartics, diazepam for seizures, and lidocaine or atropine for life-threatening cardiac effects.


• Onions and garlic can be bad for dogs.


    True: Although bad is a relative term, too much acute exposure—or to a lesser extent, chronic, low-level dietary exposure—to onion or garlic may produce depression, rapid heart and respiratory rates, and pale mucous membranes. The anemia results from free radicals that cause Heinz bodies to form, damage to red blood cells, hemolysis, and methemoglobinemia. Effects persist for several days after exposure stops. Vitamin C and/or administration of other antioxidants may have therapeutic benefits. Cooked onions and garlic are much less of a hazard than the raw food.


• Ingestion of Greenies treats is enjoyable but not risk free for cats and dogs.


    True: Greenies are hard, green, molded bone-shaped treats that contain wheat gluten, glycerin, cellulose, and other additives that are both enjoyable and nutritious for pets. Greenies are intended to be chewed before ingestion to help prevent oral odors, tartar buildup, and gingivitis. Unfortunately pets occasionally swallow large pieces of these hard treats rather than chewing them into smaller pieces. Ingestion of large pieces of Greenies has the potential of creating an esophageal or intestinal obstruction and fails to accomplish the intended use.

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Jul 18, 2016 | Posted by in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off on Facts and Fiction

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