As festive as it might be to deck the halls with boughs of holly this time of year, anyone with pets —particularly dogs and cats — should be attentive to the danger that holly sprigs and other decorative items pose to furry friends.

There are several indoor and outdoor plants that can differ in toxicity for cats and dogs. Mild cases may result in upset stomachs or lethargy, but extreme cases can be deadly.

According to pet insurance experts at money.co.uk, the ten most toxic winter plants for dogs and plants are holly, mistletoe, poinsettia plants, Christmas trees, ivy, amaryllis, lilies, Laurel plants, snowdrops, and yew.

They detail the risks associated with these plants pose as:

Holly — If the berries or spiked-edge leaves from a holly plant are ingested, this can result in irritation of the mouth, drooling, gastrointestinal upset (such as vomiting), and diarrhea. It may also cause excessive headshaking if consumed in large quantities.

Mistletoe — Though varied in types, the berries from mistletoe contain chemicals including polysaccharides, alkaloids, and lectins which are harmful to both dogs and cats. When ingested in small quantities, it can cause gastrointestinal irritation such as vomiting and abdominal pain. Consumed in large quantities, it may cause abnormal heart rate, low blood pressure, and incoordination.

Poinsettia plants — Widely known for their bright red and green festive foliage, the milky white sap from the colored leaves contains a chemical which could cause not only nausea, vomiting, drooling, and diarrhea, but also irritation in the skin, mouth, and esophagus.

Christmas trees — If the pine needles from Christmas trees are chewed, the oils released may cause irritations in the mouth as well as stomach upset. Due to the prickly nature of the needle, these could also be hazardous to the mouth, throat, and stomach if ingested.

Ivy (Hedera species) — Ivy can cause severe skin irritation if pets come into direct contact with this plant. If ingested, ivy can also cause stomach upsets.

Amaryllis — The whole amaryllis plant contains toxic substances, but higher quantities are contained in the bulb, so be careful of pets who like to dig. If consumed, they may experience severe gastrointestinal upsets (such as vomiting and abdominal pain), loss of appetite, lethargy, and tremors.

Lilies — Dangerous for both cats and dogs, if any part of a lily is ingested (even in small quantities) this could cause severe gastrointestinal damage, which may lead to kidney failure for cats.

Laurel — Laurel plants including bay laurels (which are often used in cooking) and cherry laurel, contain toxins located in all parts of the shrub which cause vomiting, abdominal pain, hypotension, and in extreme cases, muscle weakness and even seizures.

Snowdrops — These small white flowers contain toxins in their stems and leaves, with the highest concentration in the bulb. When ingested, they can cause abdominal pain, vomiting, incoordination, as well as a drop in heart rate and blood pressure.

Yew — All parts of this plant, including its leaves and berries are highly poisonous. When ingested they can cause vomiting, weakness, breathing difficulties, and in critical cases, life threatening change in heart rate and blood pressure.

Helpful Resources

Dr Nicole Sabo is an emergency room vet as well as the president of Vet Care Everywhere, which is a partner of the Catherine Violet Hubbard Foundation in Newtown.

“I run a run a charity where we do at-home veterinary care for pets of veterans, seniors, and disabled individuals throughout Connecticut,” Sabo explained.

In her line of work, she has found that while it is common to see pets poisoned by holly, yew, and mistletoe, one of the biggest dangers is lilies.

Not only are lilies of top concern, but so are outdoor mushrooms – though they are technically categorized as fungi.

Sabo explained, “Specifically outdoor mushrooms – not mushrooms that you are cooking with – are a big concern in terms of this time of year. There are a ton of toxic mushrooms that pop up in the yard. To me, that’s probably the biggest thing we see pets for.”

Pet Poison Helpline’s Fall Toxins Newsletter reported that there are some types of mushrooms that may be irritating to the stomach and intestines, as well as others that are hallucinogenic or result in fatality, such as from liver or kidney failure.

“Because certain mushrooms can be very toxic, it’s important to immediately bring your dog to a vet for decontamination (inducing vomiting and giving activated charcoal to bind up any poison). Sometimes stomach pumping (i.e., gastric lavage) is necessary in severe cases,” the newsletter noted. "In general, clinical signs seen from mushroom ingestion include vomiting, diarrhea, abdominal pain, incoordination, lethargy, tremors, and seizures, with liver and kidney damage occurring later. It’s helpful to collect all the pieces of the mushroom for later identification."

People should be mindful to check their yards frequently for mushrooms if they have dogs or outdoor cats that could access them. As for indoor plants, Sabo recommends people do their research about plants before buying them to see if they could be harmful to their pets.

“That can be really helpful. You’d be surprised what can be toxic to animals. Like people planting garlic this time of year and then their animals go and dig it up,” she said, referring to garlic being toxic to dogs and cats.

If someone believes their animal has been poisoned, the local vet advises people utilize pet-specific poison hotlines right away instead of trying to remedy the situation on their own.

She suggests using the Pet Poison Helpline, which can be accessed 24 hours a day, seven days a week (24/7) by calling 800-213-6680 and visiting petpoisonhelpline.com. There is a consultation fee.

Also, the ASPCA Poison Control Helpline is 888-426-4435 and available 24/7. There may be a consultation fee.

For a list of toxins as well as possible complications of these toxicities, visit aspca.org/pet-care/animal-poison-control.

“In general, when in doubt, reach out to proper resources,” Sabo said.

She notes that while calling your pet’s veterinarian is helpful, many times they will direct individuals to call a poison helpline.

For local emergencies, residents can contact Newtown Veterinary Specialists, which is open 24/7 at 52 Church Hill Road — 866-419-4054.

To learn more about Vet Care Everywhere and its services, call 800-533-1898 or visit vetcareeverywhere.org.

Reporter Alissa Silber can be reached at alissa@thebee.com.