Christmas cactus (Schlumbergera truncata) This plant is not highly toxic, but will cause vomiting and diarrhea. Most pet who chew on Christmas cactus will be okay, but older pets and those with medical conditions may have abdominal discomfort and may even have some blood in their stool. These pets may need to be hospitalized on IV fluids for a short period of time to support them as the symptoms pass.
Mistletoe can be a little more tricky as there is both an American and European form. Most ingestions involve American mistletoe (Phoradendron spp.). The plant contains lectins, but ingestion of a few leaves or berries will generally cause just a mild stomach upset. If purchased in a store, the berries frequently have been removed and replaced with plastic “berries” which can be a foreign object that causes complete or partial intestinal blockages. This results in vomiting and weight loss, the severity of symptoms depending on if it is a complete, or partial blockage. Large ingestions of the actual berry may require decontamination (that means inducing vomiting, and/or stomach pumping, and then activated charcoal to adsorb any remaining toxin) and then cardiovascular monitoring. Most patients just nibble and vomit.
Holly is not commonly ingested as it is a ‘prickly’ plant. However, when it is brought inside as a decoration, cats appear to find it quite tasty. All parts of the holly plant are considered to be toxic. Holly has toxins in the families of methylxanthines (same type of toxin as makes chocolate and coffee toxic), saponins, and ilicin as some of its toxic components. The good news is that true toxicoses not generally expected in cats. Most ingestions cause GI irritation and depression. Recent ingestions can usually be managed with dilution and monitoring at home.
Amaryllis are common ornamental bulb plants, forced to bloom at Christmas time. The plants contain a variety of alkaloids and galanthamine, which is a cholinesterase-inhibitor, kind of like the older flea sprays and flea collar ingredients. All parts of the plant are toxic, however the bulbs are the worst. With cats, they usually only eat the foliage and flower which only causes drooling, vomiting and diarrhea. Ingesting the bulb can cause low blood pressure, weakness, staggery and drunken gait, muscle tremors and seizures. Since cats don’t dig up the bulb, the overall prognosis is good.
Lilies aren’t necessarily a Christmas plant, but we do still find them in bouquets this time of year. Members of the Lilium andHemerocallis genera (Easter lilies, tiger lilies, day lilies, etc.) cause acute kidney failure in cats. The toxic principle is unknown, but is known to be water soluble. Even minor exposures (bite on a leaf, ingestion of pollen) may result in toxicosis, so all feline exposures to lilies should be considered potentially life-threatening!! Cats begin to vomit within a few hours after exposure. Within 24 to 72 hours of ingestion, kidney failure develops. Elevations in Blood Urea Nitrogen (BUN), creatinine, Phosphorous, and Potassium are detectable as early as 12 hours post ingestion. Creatinine elevations may be especially high. Since the toxin causes damage to the renal tubular cells, protein and glucose loss in a dilute urine is usually detectable on urinalysis within 24 hours of ingestion. If we get to these patients within the first 18 hours after ingestion they usually have a good prognosis. After 18 hours, the prognosis declines. These cats should be decontaminated aggressively. Treatment consists of inducing vomiting and administering a dose of activated charcoal. We then hospitalize the cat on intravenous fluids at a flow rate twice as high as a normal maintenance rate would be, for 48 hours. Baseline kidney values should be checked at the time that the kitty presents to the Emergency Room and then 24 and 48 hours later. If the values are normal at 48 hours, then we would sequentially turn down the fluid rate to wean the cat off fluids and then send it home. Because the tubular injury from lily ingestion spares the renal tubular basement membrane, regeneration of damaged tubules may be possible. In severe cases, peritoneal dialysis may aid in managing renal failure until tubular regeneration occurs (10-14 days or longer). This means transferring to a specialty care facility that has the capability of doing dialysis-like therapy.