Topical review
Lily Toxicity in the Cat

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Lilies are commonly kept flowering ornamental plants that are used in holiday celebrations, weddings, and funerals, and in various floral arrangements. Lilies of genera Lilium and Hemerocallis (day lilies) have been shown to cause nephrotoxicity in cats. Confusion arises because so many different plants are called lilies. Members of the genus Convallaria (lily of the valley), while sparing on the kidneys, elicit toxic effects because they possess potent cardiac glycosides similar to digitalis. Even more confusing as to which lilies are toxic is the fact that many hybrids exist. The majority of the public do not know that lilies can be dangerous to cats and, in fact, cannot correctly identify the plants in their own homes. Cats have been shown to be extremely sensitive to the toxic effects of lilies. As little as 2 leaves or part of a single flower have resulted in deaths. It should be pointed out that the whole plant—petals, stamen, leaves, and pollen are toxic. The exact toxic dose and the precise toxins responsible for renal damage are currently unknown. The quick onset of clinical signs suggests a rapid absorption rate of the toxin. The renal tubular epithelium appears to be the target of the toxin. Studies indicate that it is the water-soluble fraction of the lily that is nephrotoxic. In cats, clinical signs of lily intoxication include salivation, vomiting, anorexia, and depression. Polyuric renal failure leads to dehydration and anuric renal failure and death results. No analytic verification of lily ingestion is currently available. Successful treatment includes initiation of fluid diuresis before the onset of anuric renal failure. Once anuria develops, peritoneal dialysis or hemodialysis is the only potential treatment. Differential diagnoses of lily poisoning include any potential cause of acute renal failure in a cat. Prognosis is excellent if fluid diuresis is started before anuric renal failure has developed. The public must be made aware of potentially toxic ornamental house plants.

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Exposure

Lilies are popular decorative ornamental house plants. They are commonly found in many floral arrangements and are ubiquitous at Easter time, weddings, graduations, and funerals. They are also planted in outside flowerbeds and gardens. Typically, indoor-only house cats are more at risk and show a higher incidence of intoxication. Encourage owners to bring in any plant material that they suspect their animal has eaten for identification. It is amazing how many people do not know what type of

Toxic Dose

The lily-induced nephrotoxic syndrome has only been observed in cats.5 Cats appear uniquely sensitive to ingestion of certain species of lilies leading to nephrotoxic damage. No age, sex, or breed predilection has been identified. Nephrotoxic damage cannot be duplicated in rats, mice, or rabbits even when fed up to 1.5 times the body weight.5 In addition, the nephrotoxic effects are not seen in dogs even when fed large amounts. Vomiting and gastrointestinal signs can be seen after lily

Mechanism of Action

The exact mechanism of action of lily poisoning, specifically lily-induced nephrotoxicity, is unknown. The toxins responsible for the renal damage remain to be identified. Nevertheless, the rapid onset of clinical signs after ingestion of culprit species indicates a fairly rapid absorption rate for the poison. The toxins damage renal tubular epithelial cells resulting in cell death and sloughing of damaged renal cells. The insult to the kidney is severe, leading initially to polyuric kidney

Toxicokinetics

The quick onset of clinical signs pleads for a rapid absorption rate for the toxin. However, this rapid onset of clinical signs (vomiting in particular) may limit the amount of plant the animal can ingest. Metabolism of the toxic molecule responsible for clinical signs is unknown, but its metabolism in cats could be different enough from other species studied (dogs, mice, rats, and rabbits) that production of a feline-specific toxic metabolite could occur.8, 9, 10, 11, 12, 13 This would explain

Clinical Signs

In cats, the first clinical signs are salivation, vomiting, anorexia, and depression (Table 4). These signs typically develop within 1 to 3 hours postingestion. In other species, the only sign observed consistently is a short-lived, mild gastrointestinal upset in dogs.15 Certainly, clinical signs may differ and may depend on when the animal is brought in relative to the ingestion event. For the feline, the initial vomiting and salivation seen will last from 2 to 6 hours after exposure.

Minimum Database and Diagnostics

Strict attention to clinical signs and clinicopathological changes can help in determining the clinical phase at presentation. This approach provides a more effective treatment scheme and more accurate prognosis. A complete blood count and serum biochemical profile are necessary to identify anemia or a stress leukogram; to identify increases in BUN, creatinine, and potassium; and to determine the degree of renal effects already present. The timing of the sample taking influences the degree of

Treatment

If ingestion of toxic lilies is recent, routine decontamination procedures (emesis and evacuation of gastric contents and administration of activated charcoal) should be initiated. Often, lily-eating cats already will have vomited before presentation to the veterinary hospital; nevertheless, routine gastrointestinal decontamination protocols should be undertaken to prevent further absorption of plant toxins. Cats that have not vomited should be given emetics to remove plant toxins from the

Gross and Histological Lesions

Gross lesions found at necropsy are consistent with renal effects. The majority of pathological changes are limited to systemic congestion and renal lesions. Renal congestion with swollen kidneys and peri-renal edema are found in nearly every case. Generally, mild pulmonary congestion, gastrointestinal congestion, and paleness of the liver are seen and are thought to be secondary to severe uremia from the anuria. Hepatic lipidosis may result from the anorexia. The stomach and intestines are

Differential Diagnoses

Lily poisoning in cats can resemble any syndrome causing acute renal failure, or any cause of gastrointestinal upset (the early stages of lily intoxication). Other differential diagnoses must include infectious renal disease, metabolic renal problems, and acute presentation of a chronic underlying renal condition. Also, ingestion of soluble oxalate-containing plants and boric acid poisoning must be considered. Lily poisoning may mimic ethylene glycol toxicity; however, although cats that have

Prognosis and Prevention

Prognosis can be fairly closely called based on the severity of effects presented at the start of fluid therapy. Cats presented early and receiving decontamination and fluid diuresis have an excellent prognosis. Cats ingesting toxic lilies and receiving no treatment have a grave prognosis. Likewise, cats presenting after anuric renal failure has appeared also earn a guarded to poor prognosis unless dialysis is used. Currently, most private practices lack the ability to provide either peritoneal

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