Pumpkin spice and toxic vice: common fall toxins for pets

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Fall-a time when some natural and anthropogenic activities decrease and others increase, bringing a new “season” of potential toxic exposures and health hazards for canine and feline companions. While celebrating fall, including the holidays that occur within this time period and our preparations for winter, it's wise to keep in mind the changing natural cycles and that associated activities can increase hazards to our companion animals. By and large, dogs are the species involved in most of these exposures, but the occasional indiscriminate feline may also find itself involved with a toxic exposure.

Acorns and oak

The seeds of oak trees begin to ripen and fall in early autumn. Although not expected to cause systemic toxicosis in most cats and dogs, tannins (gallotannins) contained in the seeds can cause significant gastrointestinal (GI) irritation if a large number are ingested. Vomiting and diarrhea (+/- blood), anorexia, lethargy and abdominal pain are possible clinical signs.

Anecdotally, dogs have experienced toxicosis after drinking water soaked with oak leaves and seeds. There is also some risk of foreign body obstruction in smaller animals, especially if large quantities of seeds or even acorns are ingested. While generally confined to outdoor dogs, indoor pets may be affected if they have access to centerpieces or other displays made with oak branches containing seeds or acorns.

In rare cases, renal and hepatic injury have been reported although this is far more common in grazing animals. In cases with renal or hepatic injury, hematological changes are observed four to six days after ingestion.

Cheers to keeping alcohol away from pets!

Several holidays are celebrated within the fall period. Many of these involve the consumption of alcohol (ethanol). While moderate consumption of such libations may be acceptable for humans, you should be sure that clients know that this is not the case for cats and dogs.

Alcohol is one of our usual suspects of toxins. Here's the rundown on alcoholic beverages and toxicity to pets. Whether it's the Superbowl or a Halloween party-keep your pets safe!

Antifreeze

When prepping for winter, a common fall chore is to monitor and refill the antifreeze level in automobile radiators, recreational vehicles and some boats. Many of these products contain varying concentrations of ethylene glycol (EG), generally from 50% to 95%.

Dogs and cats are attracted to the sweet taste of the product that may be left in puddles on the ground. The lethal dose is low and the toxic potential high when ingested by dogs and cats, with permanent and life-threatening renal injury possible. As little as 1.5 mL EG/kg bodyweight (BW) in felines and 4.2 mL EG/kg BW in canines can be lethal, with signs of toxicity present at lower doses. Absorption from the GI tract is very rapid-so rapid, in fact, that in cats, decontamination and treatment must be initiated within three hours for a good prognosis, and within eight hours for dogs.

With antifreeze, two somewhat distinct stages of toxicosis occur. The first stage occurs within a few hours, although a delay of up to 12 hours has been reported in some animals. Early signs, such as vomiting, lethargy, disorientation and ataxia, look much like ethanol toxicity. Polyuria/polydipsia (PU/PD) has also been reported. Seemingly apparent recovery from these signs may occur within a day and lull pet parents into a sense that danger has passed.

A second stage, with tachycardia and tachypnea, are noted at 12 to 24 hours after ingestion. Clinical signs during this period may include anorexia, persistent emesis, lethargy, hypersalivation and oral ulcers. Cardiovascular and central nervous system (CNS) signs are also possible in this stage. Signs of acute kidney injury may be seen between 24 to 72 hours (sooner than later for cats) after ingestion, with significant elevations in the creatinine and blood urea nitrogen. The kidneys may be enlarged and present sensitive on palpation.

Prognosis for both species becomes worse as the time between exposure and initiation of decontamination and treatment lengthens. Fomepizole, the antidote, is very effective but must be administered within the treatment time frames listed above.

“Animal Safe” antifreeze formulas containing propylene glycol are also available. These too can cause a toxicosis resulting in CNS, respiratory and metabolic signs but much larger quantities of product need to be ingested and renal failure is not expected.

Chocolate: A year-round hazard

This delicious confection is a hazard that's always readily available for pets to get into, but spikes in cases of chocolate toxicity occur around Halloween and then again in later autumn as dogs raid hidden winter holiday gifts. Here are the toxicity details you need to know.

Have you heard? Chocolate might be especially bad for labs' health.

Want a handout to share with clients? Find it here.

Compost

Ah, composting! This process has several good attributes, including the reduction of waste and the concentration of valuable nutrients for next year's garden. Sadly, some people compost by piling food wastes in their yard in systems that are minimally contained or protected. With some exceptions such as raisins, grapes and xylitol-containing products, most foods put into compost bins are not directly poisonous to our pets.

The process of decomposition, however, may result in the development of toxic material. Mold that grows on or in food products such as cheese, dog food and bread in compost piles may contain tremorgenic mycotoxins, which are harmful to animals. Signs of agitation, hypersalivation, elevated body temperature, panting, vomiting and ataxia are seen anywhere from 30 minutes to several hours of ingestion. These signs can progress to severe hyperthermia, tremors and seizures that require immediate veterinary care for the animal to survive. Other compost risks include foreign body obstruction from food items such as fruit pits, watermelon rinds and corn cobs.

Holiday foods

This time of year in particular is full of seasonal parties and holidays, especially Halloween and Thanksgiving, which come with special hazards. Baked goods and candies abound, and some greedy pets feel they have as much right to partake in the goodies as humans. Unfortunately, this inclination can put a pet in dire straits.

Bread dough

Bread dough, especially yeast containing uncooked bread dough left to rise on counters, is attractive to dogs. Toxicosis occurs when products such as breads, pizza doughs, sourdoughs and other products containing live yeast are ingested. In addition to toxicity, gastric distension may lead to a mechanical obstruction.

Carbon dioxide gas produced by fermentation and enhanced by the warm, acidic environment of the stomach can cause bloat with a potential for gastric dilation and volvulus. Clinical signs include an enlarged abdomen, unproductive retching, vomiting and agitation. Ethanol, a fermentation byproduct, is rapidly absorbed from the stomach and gastrointestinal (GI) tract, with ethanol toxicity a distinct possibility.

Ingestion of even a small amount of rising bread dough can quickly become a life-threatening situation for a dog. If the ingestion is within 30 minutes and the dog is asymptomatic, induction of emesis at home may be advised. Immediate evaluation by a veterinarian may be recommended in some cases even if the previous measures are taken at home.

Raisins

Raisins can be found in many home baked goods, purchased bakery products, fresh salads and candies. Ingestion of just a few raisins in some dogs has caused renal failure, while other dogs haven't developed any known problems. The underlying reason for this is unknown and as such, there is no currently established toxic dose.

Raisins, as yet, have not been demonstrated to be a feline toxicity. Raisins can remain in the stomach for up to six hours, so there's a wide window for decontamination in an asymptomatic dog. Asymptomatic, emesis-eligible dogs with relatively recent exposures may be vomited at home and the return assessed. If the return is incomplete or vomiting does not occur, further aggressive therapy by a veterinarian is recommended to reduce the possibility of renal injury.

Macadamia nuts

Macadamia nuts (Macadamia integrifolia and Macadamia tetraphylla) are toxic to dogs with GI, CNS and musculoskeletal signs possible. The nut is not known to be a feline toxin.

The toxic dose is considered to be 2.2 g nuts/kg BW, with signs in some dogs at 0.7 g/kg BW. Vomiting, hyperthermia and lethargy are reported at 6 hours of ingestion, progressing to ataxia, lethargy, tremors, muscle weakness at six to 12 hours. Resolution generally takes 24 to 48 hours. Close attention should be paid to the body temperature and measures taken as needed to reduce it. Macadamia nuts are approximately 75% fat, so pancreatitis is an expected sequela.

Xylitol

Xylitol toxicity is possible in any situation where sugar-free baked goods are baked, purchased or served. So far, toxicity is confined to dogs;  only a few, sporadic anecdotal cat ingestions have been reported. Hypoglycemia, manifested as weakness, depression, ataxia or tremors, develops within 10 to 120 minutes with ingestions greater than 0.1 g xylitol/kg BW.

Occasionally, a delayed onset occurs, with seizures the first noted sign. At higher doses (0.5 g xylitol/kg BW), hepatic injury and failure are likely. In these cases, increased concentrations of liver enzymes are often detected within 12 to 72 hours. Hepatic necrosis may result in further hypoglycemia, icterus, coagulopathies and hepatic encephalopathy. Early and aggressive decontamination; treatment and supportive care for hypoglycemia; and hepatic enzyme monitoring are required for a good prognosis.

Houseguests

Houseguests often come with fall holidays such as Thanksgiving. These are often people who don't have pets and aren't used to keeping their medications or illicit substances out of reach. Grandma's seven-day pillbox can rapidly become a complicated polypharmacy ingestion if a dog or cat has access to this consolidated pharmacy. In a similar vein, the stash of illicit substances in Cousin Larry's suitcase can quickly turn into a trip to the local emergency veterinary clinic.

Insulation

Fall is all about preparing for the cold and battening down the hatches. This is a time when we may be adding extra insulation to areas of our homes. Modern insulation can contain various materials, including fiberglass, cellulose, foam and wire wool. By and large, these ingestions pose more of a GI irritation and foreign body problem rather than a toxicity risk, but it's still important to keep pets away from them and prevent ingestion. Dermal irritation is also possible with exposure to these materials.

Mothballs

Benign as these small round balls may seem, they can pack a toxic punch for our pets when ingested. Mothballs come in three different formulations: naphthalene, paradichlorobenzene and camphor. Of these, naphthalene and paradichlorobenzene are the most common, with naphthalene generally considered to be the most toxic.

Naphthalene

Gastrointestinal, CNS and hematological effects are commonly associated with toxicity in dogs. Depending on the concentration of naphthalene, ingestion of just one mothball may be toxic in a 10 kg dog. Signs generally take hours to days to develop as the mothballs dissolve very slowly in the GI tract. Common clinical signs include vomiting, abdominal pain, lethargy, naphthalene odor in the breath, and seizures. As time passes, signs of toxicosis progress to dyspnea, methemoglobinemia, Heinz body hemolytic anemia, hemoglobinuria, hepatic injury and nephrosis. Naphthalene mothballs are radiolucent, making it difficult to identify them on radiographs.

Paradichlorobenzene

Even though the toxic potential is less, ingestion can still result in GI and CNS signs and, in rare cases, hepatic, renal and hematological effects. In general, a larger number of mothballs need to be ingested for toxic effects to appear (approximately three or more mothballs in a small dog as opposed to one for naphthalene). Paradichlorobenzene mothballs are radio-opaque and more easily found on radiographs.

Camphor

Ingestion of camphor can cause respiratory and CNS signs. Less information is available regarding toxic pet exposures involving this product. In addition to using radiographs to assist in the diagnosis, mothballs have some unique characteristics that can aid in identification:

• When soaked, naphthalene mothballs will sink in water but float in salt solution.
• When soaked, paradichlorobenzene mothballs will sink in both water and salt solution.
• When soaked, camphor mothballs will float in both water and salt solution.

Mushrooms

While the shitakes or creminis in your refrigerator may be an integral part of your cuisine, the fungi that grow in your yard or in the woods where you walk your dog may have very toxic consequences if eaten.

In the fall, rain is abundant in many parts of the world, and these wet conditions allow mushrooms to flourish. Mushrooms comprise a myriad of species and types that can cause a plethora of toxicities, including those that cause GI, CNS, hallucinogenic, muscarinic and hepatobiliary signs.

Any mushroom exposure that did not come from a kitchen is considered potentially toxic. While some of the outdoor mushrooms may be edible, many are not, and it often takes a mycologist to accurately identify the mushroom and the toxic potential. Mushroom ingestions by pets are considered an emergency, and there is generally not enough time for identification before action needs to be taken.

Early and aggressive decontamination is generally warranted. Mushroom pieces should be collected, placed in a paper bag, labeled “do not eat” in large letters and refrigerated for the time when the mushroom needs to be identified.

Rodenticides

As cool weather creeps into fall, so rodents creep into homes. Many people attempt to protect their homes using a variety of different rodenticides. The three most common rodenticides used in homes are the older, long acting anti-coagulant types, which are currently limited to agricultural sales in the United States, but readily available in bromethalin and Vitamin D3 (cholecalciferol) at most farm-type stores. Products containing phosphides are generally used in the yard to kill moles, voles, gophers and other burrowing mammals, but may be used by some individuals for specific fall applications.

• In all animals, excessive amounts of a long-acting anti-coagulant rodenticide result in internal bleeding. Clinical signs, including lethargy, petechiae, hematemesis, hematochezia, hematuria, frank bleeding and dyspnea, generally occur in two to five days. Diagnosis is made based on a prolonged prothrombin time (PT), a blood test that measures the time it takes for the liquid portion of the blood to clot. Phytonadione (Vitamin K1) is an effective antidote if used early; transfusions and other symptomatic supportive care may be needed for more severe cases.
• Bromethalin is a dose-dependent rodenticide that produces marked CNS effects. Agitation, hyperesthesia, severe tremors and seizures occur within two to 24 hours in dogs ingesting more than the reported LD50 (2.38 to 4.7 mg bromethalin/kg BW). In dogs, ingesting less than the LD50 signs may take as long as one to five days to occur and include hind limb ataxia, CNS depression, paresis and, in severe cases, paralysis. At post-mortem, most of the lesions are confined to the CNS, with gross evidence of cerebral edema present.
• Ingestion of a Vitamin D3 (cholecalciferol) rodenticide can cause extremely high calcium and phosphorus plasma or serum concentrations. Serum calcium concentrations greater than 12.5 mg/dL and serum phosphorus concentrations greater than 7 mg/dL are associated with a potentially life-threatening situation. Left untreated, these abnormalities lead to cardiovascular and renal problems. Other organ systems such as the GI tract, respiratory and CNS may also be affected.

Clinical signs tend to develop in stages and include PU/PD at 0 to 24 hours; anorexia, vomiting, lethargy, weakness and melena at 12 to 36 hours; hypercalcemia and hyperphosphatemia at 24 to 48 hours and soft tissue mineralization days to weeks later. While not a true antidote, a bisphosphonate drug such as pamidronate has been used effectively to help lower serum calcium. Cholecalciferol has a very narrow margin of safety (toxic dose 0.1 mg/kg BW to 0.5 mg/kg BW in dogs and cats) and generally requires long and arduous treatment for a good outcome.

• Phosphide rodenticides (zinc, aluminum, magnesium) have a very narrow margin of safety, with GI, cardiovascular, respiratory and CNS effects possible. The onset of action is rapid, usually within 15 minutes to an hour. In a few rare cases, signs have been delayed for up to 24 hours.

Common clinical signs include vomiting with or without blood, diarrhea, tachypnea, pulmonary edema, tachycardia, arrhythmias, lethargy, tremors and seizures. The smell of rotten fish is often noted on the animal's breath or in the vomitus. Ingestion of a phosphide rodenticide results in the formation of phosphine gas, a highly toxic gas. The addition of food, water or hydrogen peroxide to the acidic nature of stomach can potentiate this, and if vomiting occurs, exposure to the phosphine gas is toxic to humans.

Pet parents whose animals have ingested phosphide rodenticides should be advised to seek immediate veterinary care. No decontamination should be attempted at home, and if the pet should vomit during transport, then the car windows should be opened to provide ventilation. Induction of emesis at the hospital should only be attempted in areas with good ventilation.

Twine, nettings and strings

When wrapped around a roast, cooked in its juices and discarded, butcher's twine makes an especially attractive hazard for pets. This string or netting can be ingested in woven patterns or long lengths that can put pets at risk for the dangers of a linear foreign body. Fat-saturated strings, when ingested, may also increase the risk of pancreatitis in some dogs.

Ribbons and other strings used to wrap food containing packages may smell good enough for the curious dog or cat to mouth and swallow, resulting in a foreign body. All of these should be safely discarded in the trash and not put in with composted material.

As with any season, the potential toxic exposures and hazards prevalent in the fall can be avoided with a little prudence by the pet owner regarding storage and placement of these goods. With thoughtful preparation, the gifts of this season may be enjoyed without harm to animals. Sometimes, however, even in the best situation, toxic exposures occur and veterinary poison control centers such as the Pet Poison Helpline are available 24 hours a day, 7 days a week to assist veterinarians with these cases.

Renee DiPietro, CVT, LVT, is associate veterinary information specialist, and Lynn R. Hovda, RPH, DVM, MS, DACVIM, is director of veterinary medicine with SafetyCall International and Pet Poison Helpline in Bloomington, Minnesota.

Suggested reading:

Gupta RH. Veterinary Toxicology, 3rd ed. 2018. Academic Press, London, UK.

Hovda LR, Brutlag AG, Poppenga RH, Peterson KL. Blackwell's Five Minute Veterinary Consult Clinical Companion Small Animal Toxicology, 2nd ed. 2016. Wiley Publishing, Ames, IA.

"Don't deck the halls with these holiday hazards"

Peterson ME, Talcott PA. Small Animal Toxicology, 3rd ed. 2013. Elsevier Saunders, St. Louis, MO.

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