Exposure Circumstances and Outcomes of 48 Households with 57 Cats Exposed to Toxic Lily Species

Introduction

In 1992, a syndrome of renal failure in cats secondary to ingestion of leaves and/or flowers of members of Lilium and Hemerocallis spp. was reported at a veterinary conference.¹ Since that time, information on the toxicity of lilies to cats has been disseminated to the veterinary community and public through various media, including television, print, radio, and the Internet. Despite these attempts at informing cat owners of the hazards that lilies pose to cats, each year the American Society for the Prevention of Cruelty to Animals (ASPCA), APCC receives several hundred calls regarding feline exposures to these plants. A recent international conference on the human–animal bond, including a poster presentation on lily toxicosis by one of the authors, indicated that only a small number of attendees were aware of this hazard (M.S., personal communication, 2010). Based on data generated at the authors’ institute, the incidence of lily toxicosis has increased yearly, with 299 cases in 2006, 326 cases in 2007, and 405 cases in 2008 (ASPCA APCC, unpublished data).

Cats are the only species in which ingestion of lilies has been associated with acute renal failure.² All parts of the plant, including the pollen, are considered toxic, and renal injury has occurred after what many cat owners would consider minor exposures.³ After lily ingestion, affected cats often develop vomiting or lethargy within 2 hr. These signs may be transient, and many cats appear to recover, only to deteriorate 24–72 hr after exposure. Affected cats show signs of renal failure, including polyuria, polydipsia, and profound central nervous system depression. As signs progress, either oliguric or anuric renal failure can occur and death occurs within 3–6 days after exposure to a lily. The best chance of successful treatment of lily toxicosis is the institution of aggressive intravenous fluid therapy within the first 18 hr after exposure; delays beyond this time frame greatly reduce the prognosis for successful outcome.²

The primary objective of this study was to evaluate whether owners of cats with indoor exposure to poisonous lily species were aware that these plants were toxic at the time of exposure and, if so, how they obtained that knowledge. The secondary objectives were to obtain information on the source of the flowers, the circumstances surrounding the exposure, and the clinical conditions of exposed cats at the time of the follow-up interview.

Materials and Methods

Subjects

Telephone calls originating from cat owners to the APCC regarding confirmed exposures of cats to Lilium species and Hemerocallis species between April 1, 2009 and April 30, 2009 were eligible for a follow-up interview (calls originating from veterinarians were excluded). The month of April was chosen because it was the month in which Easter Sunday fell, which has been traditionally the month that the APCC receives the largest volume of calls of feline lily exposures (ASPCA APCC, unpublished data). The APCC's computerized record of all medical data collected since the initial phone call were examined, and basic signalment, historical, and clinical information were obtained. Upon initial contact of the owner with the authors’ institution, the APCC veterinary staff collected information regarding the breed, sex, age, and weight of the cat, as well as the brief circumstances surrounding the exposure, any clinical signs that developed, and any treatments that were initiated. Through follow-up, calls throughout the course of the case that were treated at other veterinary hospitals, updated information on the clinical status of the cat, any clinical laboratory alterations that developed, and response to treatments were recorded in the medical record. Follow-up interviews were attempted for 56 cases, with a goal of having at least 40 completed interviews. Owners of cats known to be extremely ill, dead, or euthanized at the time of the most recent telephone call were not contacted for an interview.

Questionnaire

A six question survey designed to be administered by telephone was created (Figure 1). All but two questions were open ended, with the interviewer providing with the most commonly expected answers if prompts were needed. The interview began by asking the cat's current clinical condition. Next were questions about whether the owner often had live flowers in the house (yes or no) and where they obtained the flowers. The authors asked if the owner could recognize lilies in a bouquet (yes or no) and if the owner knew that flowers in the bouquet might be toxic to the cat. If the owners knew lilies were toxic, the authors asked where they had obtained that information. Finally, the authors asked for details on how the cat was exposed to the flowers; this was of particular interest for owners who knew that lilies were toxic before the exposure.

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The survey was administered by trained customer service staff via telephone interviews that continued until May 15, 2009. At least three calls to each included case at various times and days were made, leaving messages, if possible, for unsuccessful contacts. APCC case records were examined for owners who could not be reached for interviews to determine whether the historical data collected on the initial contact included information that would answer the survey questions; if so, the data were included in the study.

Statistical Analysis

Open-ended questions were categorized into common responses. All questions were then summarized using counts and percentages. Exact binomial 95% confidence intervals (CIs) were calculated for all exposure circumstances and outcome estimates.

Results

The median time between initial contact of the APCC and follow up was 7 days (range, 1–33 days). Fifty-nine owners of cats with confirmed Lilium spp. or Hemerocallis spp. indoor exposures were initially selected for interviews. Three owners were not contacted due to severe illness or known euthanasia of the cats, and three owners were excluded due to a difficult initial contact. The authors did not contact owners of deceased cats to avoid causing them additional distress; data from the medical records were used instead. Ten owners were not able to be reached by the end of the study, for a final response rate of 81% (43/53). Three cats that died or were euthanized and two cats whose owners were not able to be reached had sufficient historical data in the record to be included in the analyses.

Of the 48 owners included in the study, 3 owners had more than 1 cat exposed (2, 3, and 7 cats) for a total of 57 cats. There were 42 domestic shorthairs (74%), 5 domestic longhairs (9%), 3 American shorthairs (5%), 2 domestic medium hairs (4%), and one each of Bengal, Maine coon, Persian, Siamese, and unknown breed.

There were 26 spayed females (46%), 1 intact female (2%), 25 castrated males (44%), 2 intact males (4%), and 3 unknown sexes (5%). The median age of the cats was 3.5 yr (range, 5 mo to 16 yr of age). The median weight of cats was 5 kg (range, 1.8–9 kg). The rest of the analyses were done by household, not by individual cat. The most common states the owners lived in were Virginia (eight owners), New Jersey, Ohio, and Pennsylvania (four owners each), and Connecticut and Illinois (three owners each). California, Maryland, and Massachusetts had two owners each. Twelve other states were represented by one case each. There were also four Canadian callers.

Twenty-seven percent (13/48; 95% CI, 15–42%) of owners knew that lilies were toxic before the cat's exposure. Sixty-nine percent (33/48; 95% CI, 54–81%) of owners were able to recognize lilies in a bouquet of flowers, and 62.5% (30/48; 95% CI, 47–76%) of owners did not often have live flowers in the house. Those owners with foreknowledge of the toxicity of lilies had obtained this information from (one owner each): a previous cat's exposure, the ASPCA newsletter, the ASPCA website, a brochure given to the owner when the cat was acquired, a postcard from the owner's veterinarian before the exposure, veterinary school or veterinary technician school, and the Internet (two owners). The majority of owners (19/23 who provided this information; 95% CI, 61–95%) who did not know the lily was toxic obtained the information via an Internet search soon after the cat was exposed.

The majority of cat owners who did not know lilies were toxic placed the flowers in areas to which cats had relatively easy access (23/31; 95% CI, 55–88%). Other owners (7/31; 95% CI, 10–41%) had placed the flowers out of the cats’ reach only to have the cat climb or jump up to the plants (5/31), or a household member provided the cat access to the lilies (2/31); one response regarding location of the plant and circumstances of exposure was unclear. Three owners did not provide an answer to this question, and one was not sure. One cat used its claws to scale an upholstered area and access the flowers.

The circumstances under which the cats were exposed in households where the owner knew lilies were toxic involved: the cat pushing open a door or climbing to a shelf (where the cat normally did not go) to reach the lilies (7/13), the owner accidentally leaving the lilies out for a short time where the cat could reach them (4/13), and another member of the household allowing the cat access to the room with the lilies (2/13). Almost half the lilies were gifts to the cat's owner (Table 1). Grocery stores were significantly more common sources of flowers when owners or family members purchased the flowers than any other source (Table 2).

TABLE 1 How the Lilies Came to Be Found in 48 Cat-Owning US Households

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TABLE 2 Sources of Lilies Ingested by Cats in 26 Households Who Provided Answers to This question

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Among the 55 cats with outcome data at the time of last follow up, 48 of 55 (87%; 95% CI, 75–95%) either developed no signs of toxicity or had brief clinical signs of toxicity that resolved. Three cats still had abnormalities in renal laboratory results (5.5%; 95% CI, 1–15%), one had aspiration pneumonia (1.8%; 95% CI, 0.05–10%), and three were euthanized due to renal failure (5.5%; 95% CI, 1–15%). Therefore, a total of 6 of 55 cats (11%) developed renal signs. Fifty-three (93%; 95% CI, 83–98%) of the 57 cats were taken to veterinary clinics, treated aggressively with decontamination and intravenous fluids, and had at least one complete blood count and blood chemistry performed as per APCC recommendations.

Discussion

Despite the 17 yr that have elapsed since the first published report of lily toxicosis, less than one-third of the cat owners in this survey were aware of the hazards of lilies to cats before their cat being exposed.¹ It can easily be argued that cats belonging to owners unaware of the hazards of lilies would be at increased risk of exposure, as there would be no incentive for these owners to try to limit exposure of cats to the plants, making this study subject to a sampling bias. However, the goal of this study was not to determine the prevalence of knowledge of the hazards of lilies among all cat owners (which would be an interesting study in itself) but to determine to what level exposure of cats to lilies was related to the owners’ knowledge of the hazard of these flowers to cats among owners who contacted the APCC.

Not surprisingly, the majority (73%) of cat owners who were unaware of the toxicity of lilies left the flowers out in areas of relatively easy access to the cats. Of the few owners who attempted to keep the cats away from the lilies, primarily to prevent the cats from destroying the plants, the cats managed to overcome these barriers to gain access to the flowers. Similarly, of the 27% of owners who were aware of the toxicity of lilies, the majority of exposures occurred in situations where efforts that had been made to keep the cats away from the flowers were thwarted by the cats themselves. In all of these situations the cats actively searched out the plants, going where they normally did not go and, in some cases, exerting a significant amount of effort to reach the lilies. Whether this apparent attraction of the cats to the lilies was driven by the novelty of new flowers in the home (because the majority of owners did not normally have flowers in the home) or some unique attraction of the lilies to the cats is not known, but it does indicate that cat owners should be aware that exposures may occur even when good-faith efforts to separate cats and lilies have been made.

The various means by which owners who were aware of the hazards of lilies to cats (Internet, websites, newsletters, brochures, veterinarians, etc.) obtained that information indicates that there were attempts being made by a wide variety of groups to educate cat owners. The majority of owners who were unaware of lily toxicosis before their cat's exposure were able to find the information quickly via the Internet. Simple Internet searches for “cat” and “lily” bring up dozens of websites discussing the toxicity of lilies to cats, making it relatively easy to discover that lilies are toxic, at least after the fact.

The authors’ findings indicated that the majority of lily exposures were to flowers that were purchased at a grocery store or department store and not from a florist or plant specialty shop, making education at the source of purchase difficult. Retailers may be understandably reluctant to provide information that might have a negative impact on flower sales. An alternative means of client education would be for flower retailers to provide information on less toxic flowers, bouquets, and plants available to cat owners. These “pet friendly” items would be a positive spin for the retailers and a means of education for pet owners.

In previous reports of feline lily toxicosis, the mortality rate was estimated at 50% to 100%.⁴ Of the cats included in the study, 55 had outcome data and 48 of those cats had no signs develop or developed signs that resolved with treatment, indicating that positive outcomes are possible.

The recommendations from the APCC for lily exposures are to take the cat immediately to the veterinarian and have the veterinarian call back for patient management information. The treatment information provided to veterinarians includes decontamination, protection of the kidneys by intravenous fluid dieresis for at least 48 hr (longer if renal insufficiency develops), and monitoring renal blood work every 24 hr and urinalysis every 12–24 hr.² Given the success of this protocol in the cats in this study, it appears that veterinarians have a good chance of preventing renal failure in cats exposed to lilies if they are treated rapidly and aggressively. However, this treatment protocol is quite expensive and stressful to cats, making prevention of exposure the preferred alternative.

Conclusion

Despite the 17 yr since publication about lily toxicosis in cats, only 27% of cat owners in this study were aware of hazards that lilies pose to cats. Better ways to inform cat owners of this preventable and potentially fatal flower poisoning are still needed. Most of the lilies came from nonspecialty vendors (grocery and department stores), making education regarding lily toxicosis at point of sale problematic. Many cats thwarted the owners’ attempts to keep them away from the lilies, even when owners were aware of the hazards of lilies. Only 10% of cats in this study developed severe renal injury, and the 5% mortality rate seen in this group of cats was significantly lower that the previously reported 50–100% mortality in lily toxicosis, demonstrating that prompt and aggressive veterinary intervention is invaluable in feline lily exposures.