Today on Dogster I wrote about one of veterinary medicine’s greatest mysteries: grape toxicity in dogs. Grapes, or perhaps just some grapes, contain an unknown toxin (or perhaps several toxins) that can cause kidney failure in dogs (although not all dogs appear to be sensitive to the toxin). It is presumed that cats also may be sensitive to the toxin, but fortunately cats rarely eat grapes. That said, all cats are unique individuals and there may well be cats out there who find grapes or raisins palatable. If you own such a cat, don’t let him eat grapes or raisins.
Grapes are for the most part a canine mystery. But cats have a mystery toxic plant of their own: lilies. And the similarities between grape toxicosis in dogs and lily toxicity in cats are striking.
Lilies cause kidney failure in cats. It is different from chronic kidney failure, about which I wrote last week. Chronic kidney failure is a long-term, organic disease of cats. Lilies cause sudden or acute kidney failure due to toxic effects on the kidneys.
The toxin or toxins in lilies have not been identified. All parts of the plant are toxic. Cats that consume leaves or flower petals are at risk. Cats who are dusted with pollen, or that walk through pollen on a surface, may subsequently swallow the pollen as they groom themselves and be at risk of toxicity. Many of the most dangerous types of lily, such as the stargazer, drop lots of pollen onto surfaces; pollen exposure is therefore a common phenomenon.
Adding to the confusion are the many different types of plants that are called lilies. Not all of them are true lilies. And there are countless lily hybrids out there. If your cat consumes a portion of a plant that looks like a lily, is she at risk of toxicity? There are two genera of lily plants that cause kidney failure: Hemerocallis and Lilium. Members of the Hemerocallis genus include daylilies (some of which, ironically, are edible for humans but all of which should be considered toxic for cats). The Lilium genus contains the dreaded stargazer (which is incredibly common in floral arrangements) as well as the turk’s cap, Bolander’s, and Washington lilies. If the common name of a lily consumed by a cat is known, Google can generally provide its genus. However, when in doubt the safest action is to behave as if any plant that looks like a lily is toxic.
Note that lily of the valley, which is in the genus Convallaria, has not been linked to kidney failure in cats. But it can cause heart problems, and therefore also is toxic.
The first symptom of lily toxicity in cats often is excess salivation. This may be followed by vomiting, poor appetite, and lethargy. Affected cats then begin to experience kidney toxicity. In the early stages cats suffer from a type of kidney failure in which the cat produces excessive urine. However, the vomiting and excessive urine production rapidly lead to dehydration. It is believed that the dehydration concentrates the toxin or toxins in the kidneys. This leads to death of specific cells in the kidneys. The kidneys then shut down and produce little or no urine.
Once a cat reaches that final stage — dehydration with kidney shut down — there is virtually no treatment available outside of advanced tertiary referral centers that can offer dialysis and kidney transplant. That is the bad news.
The good news is this: Cats who receive intervention before their kidneys shut down generally have good prognoses.
Treatment for lily ingestion involves several steps. The first, in cases of recent ingestion, is decontamination. This is most easily accomplished by causing the cat to vomit. (Note that the vomiting caused by the lily itself often occurs too late to be of benefit.)
Decontamination in dogs is a relatively easy thing: A medication called apomorphine can be mainlined, causing rapid nausea and vomiting. As you know, cats are unique creatures — they are not little dogs. The same cat who reliably vomits any time an expensive new carpet is introduced into the house may not vomit at the vet’s office when it really counts. Apomorphine generally is not effective, and is therefore not recommended in cats.
The medication most commonly used to induce vomiting in cats is called xylazine. It’s an old-school drug, and in my experience it works about half of the time. There are other, not recommended and less frequently used tactics as well. I once cringed as I watched an older vet treat a cat who had eaten a lily leaf. He poured salt into the cat’s mouth and then washed it down with hydrogen peroxide. Fortunately the cat vomited, and brought up the lily leaf. But if he hadn’t vomited he would have had two additional serious problems besides lily toxicity: salt poisoning and gastrointestinal ulceration from the peroxide. (And, in fact, he probably did suffer ulceration even though the treatment worked. A significant proportion of cats who ingest hydrogen peroxide will develop esophageal or stomach ulcers even if they vomit.)
In my experience, if a cat won’t vomit after receiving xylazine, the best way to achieve effective decontamination is to perform endoscopy to remove the plant material. However, endoscopy is not universally available.
Whether or not decontamination is successful, cats who consume lilies should be hospitalized for IV fluids. These fluids prevent the dehydration that appears to be a crucial step in the development of kidney failure. They also dilute the toxin in the kidneys, making it less potent. As long as the kidneys continue to produce urine, the cat is likely to survive. Several days of hospitalization may be necessary, urine output must be monitored, and blood work must be run serially to check for evidence of kidney failure.
Finally, although vomiting is desired immediately after ingestion of lily, it contributes to dehydration if it becomes protracted. Anti-nausea medications and gastrointestinal protectants are therefore often a part of the treatment for affected cats.
Although rapid intervention leads to high survival rates, cats can get into trouble if they consume lilies and their owners don’t know about it. These cats may become too sick to treat before anybody realizes anything is wrong.
Therefore, although I have said it before, I’ll say it again. The only true way to keep your cat safe is to have a lily free house.
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