Xylitol Toxicity – chewing gum IS bad for dogs

January 1, 2009

This article was originally published on my AgilePooch website, but I decided it was important enough to re-post here. The more search hits, the better the opportunity to get the word out.

The Discovery

tridentgumOn Tuesday 12/2/08, I arrived home from work to find, amidst other remnants of dog naughtiness on the bedroom floor, the remains of what I knew had once been an unopened 18-pack of Trident Original gum containing Xylitol. The package had been on the top shelf of a bookcase, which meant that one of the dogs had jumped up on a crate, and stood up on his/her hind legs to retrieve the prize from the shelf. Also on that shelf was a small bowl of treats that I keep handy for rewarding good behavior – no doubt that was the attraction, and the pack of gum was just a bonus. Billy, my new rescue, was the prime suspect. Not that the older dogs are so well-behaved, they just aren’t likely to put out that much effort for a couple of Charlee Bears.

I had missed or ignored the warnings about Xylitol that had been circulating in the previous months, but fortunately, I actually read and paid attention to the notice I was forwarded the night before this happened. Had I not received that e-mail, I might not have given this episode another thought and it’s very likely that my dog would have gotten very sick or worse. Instead, I called the Animal Care Center in Rohnert Park and was advised to bring all three dogs in immediately, which of course I did. We arrived just after 7:00pm.

The Culprit/Victim

billy-frontSince Billy was the most likely culprit, he got treated first. His stomach contents confirmed his guilt, containing gum wrappers and non-distinct white blobs (presumably wads of gum). It seems that during his brief bedroom raid, he also got a few other things, including a bright red nylon/velcro collar wallet-like thing and what appeared to be a chunk of “skin” from a plush toy. Dr. Olson pointed out that it was the most interesting puke he had seen in a while.

More importantly, Billy’s blood glucose (BG) level had already dropped to 62, even though he was otherwise asymptomatic. Billy went on to astonish the hospital staff by happily lapping up 100ml of activated charcoal from a bowl – apparently, this is unheard of (most require force feeding with a tube) and further indicates his willingness to ingest just about anything (note to self…). By 11:00pm, his BG had recovered to 98, but we were advised to leave him for the night for additional blood sugar and ALT level monitoring to be sure there were no signs of liver failure. Turned out to be a good choice, because overnight his BG dropped back down to 57, at which point he was put on IV fluids and supplemental dextrose. And though his BG rose with that treatment, it continued to hover under 90 for a while, indicating that he was still in some trouble. At midnight, they discontinued the IV to see if he could sustain his BG through the night, which he did. After a final ALT test on Thursday morning, he was released to go home – 36 hours after admission.

The Other Dogs

Because we couldn’t be sure Billy was the only victim, Jasmine and Zack were also subjected to the ignominy of “emesis induction”, as it is euphemistically referred to on the invoice. Neither showed any obvious evidence of ingestion, but in the interest of safety (some might call it paranoia), we had their blood tested as well. Amazingly (because he is a well-established counter-surfer himself), Zack came up clean with a BG of 100 so he was released on the spot. But Miss Jasmine tested at 77, requiring a follow-up test to be sure she hadn’t also grabbed an opportunistic chew. She was released after a couple of hours when she held steady at 77, still on the low side of normal but at least she wasn’t dropping. The next day I checked with her regular vet and learned that her BG was 81 just a few months ago, so no apparent cause for concern.

What is Xylitol, and why are we just starting to hear about it?

Xylitol is a sugar alcohol, or polyol. It is used as a sugar-substitute, most commonly in gum and candy, but showing up more and more in other sugar-free products. It isn’t always well labeled, so you need to put on those reading glasses and read the fine print.

Reports of Xylitol Toxicosis are fairly new, simply because Xylitol hadn’t been used much in American products until about 2004. That’s when Trident starting adding it to some of its gum, followed in 2006 by Wrigley’s Orbit line. But more recently, it has started showing up in other products, like Flintstones vitamins, Jell-O and Tom’s of Maine toothpaste. It has also been observed that Rescue Remedy pastilles (candies) now contain Xylitol. This recently caused a stir in the dog community because some dog owners give their dogs Rescue Remedy products, but the Pet liquid does NOT have Xylitol – just the human candies.

We can expect to see more and more Xylitol in products, and not just for its sweetening properties. Apparently, it has been shown to provide oral health benefits because it starves the plaque-inducing bacteria and kills them. Because of this, it is starting to show up in toothpaste and other dental products. In fact, there is a company called Epic Dental that sells all sorts of Xylitol products, including a gum containing more than six times the amount of Xylitol as in Trident Original. They tout this as a good thing – I see it as lethal.

Why is it so dangerous to dogs?

veterinary_dog_bIn humans (and apparently in cats), Xylitol is absorbed slowly and thus is not toxic. In dogs, on the other hand (and perhaps rabbits and ferrets as well), it is absorbed extremely quickly. The immediate result is that it fools the pancreas into releasing a huge spike of insulin, which is quickly followed by a precipitous drop in blood sugar (acute hypoglycemia) since there isn’t really any surplus sugar for the insulin to work on. That’s what we saw in Billy and were concerned about in Jasmine. The next problem, which isn’t quite as well understood, is severe (and often fatal) liver toxicity and failure. There isn’t yet clear evidence of causation, and Dr. Olson suggested that these cases may be due to late discovery and a progression of the severe hypoglycemia rather than a direct connection to the Xylitol. Either way, it isn’t good.

What makes Xylitol worth every bit of fear is that it takes only a small amount to cause significant harm, even in big dogs, and the harm can quickly be irreversible or fatal. To quote the VP Client Information Sheet on Xylitol Toxicosis (referenced below): “The prognosis is good for uncomplicated hypoglycemia when treatment can be instituted promptly. Liver failure and bleeding disorders generally carry a poor prognosis. Dogs that develop stupor or coma have a grave prognosis.”

How much Xylitol is in what?

It turns out that this is amazingly difficult to figure out. And because the effect on the dog is directly tied to the amount consumed relative to body weight, it is extremely important to know. Why is it so hard? Because the sugarless products that include Xylitol usually also include other sugar alcohols, with names like Sorbitol, Mannitol, Glycerol, Maltitol, and Other-things-ending-in-ol. Of these, the only one that is toxic to dogs is Xylitol. But in the Nutrition Facts on the label, they are all lumped together as “Sugar Alcohol” so that all you know is the total, not how much is actually contributed by Xylitol.

Because of this ambiguity, unless you can find another source for the specific product in question (as I was able to do), the only choice is to assume the worst case – that the entire Sugar Alcohol content is due to Xylitol. Most gums that contain Xylitol have a total Sugar Alcohol content of about 1g per stick. We were lucky because I was able to find a reference for the exact Xylitol content of Trident Original, which was much less – 0.17g per stick.

How much Xylitol does it take?

Because the problem is relatively new, there isn’t enough data to clearly establish the levels associated with toxicity. However, the best sources we found suggest that hypoglycemia occurs at 100mg/kg, and that liver problems may present at 500mg/kg. We were able to calculate that Billy had ingested about 150mg/kg, which is consistent with his presentation and progression.

Here is the calculation we used:

  • Amount of Xylitol per stick of Trident Original gum: 0.17g (170 mg)
  • Number of sticks per pack: 18 (yes, it was unopened and he likely ate the whole thing)
  • Billy’s weight: 20 kg (44 lbs)

Result: 170 mg/stick X 18 sticks / 20 kg = 153 mg/kg

I found the Trident content on the Epic Dental site, in a table bragging about high-Xylitol levels in their gum (mentioned above) compared to other brands. Most of the other products listed are not mainstream, so I assume they are other oral health products, but they happened to mention Trident. I have found no references that give this level of detail on other products. But I did manage to extrapolate from Wrigley’s oral health site that in Orbit gum, the Xylitol component of the total sugar alcohol varies from 15% to 32%, which assuming 1g per stick, means 0.15g to 0.32g per stick. Good luck finding anything else – if you do, let me know and I’ll update this page.

References (updated 8/20/15)

  • VP Client Information Sheets: Xylitol Toxicosis – This is the paper that Dr. Slater found, with the most current information on levels of toxicity associated with hypoglycemia and liver failure. The accompanying chart is astonishing – it shows the increase in Xylitol poisoning cases as reported by the ASPCA Animal Poison Control Center.
  • Pet Health Library: Xylitol Poisoning – this one is interesting because at the end, it suggests that the oral health benefits of Xylitol might still be appropriate for dogs as a low-level water additive. Yikes, I think I’ll pass. I have since learned that C.E.T AquaDent contains Xylitol, but C.E.T. Chlorhexidine Rinse does NOT. My concern is this: the recommended teaspoon may not contain enough to be harmful, but what if the dog gets the whole bottle? I can’t find any reference to the overall content. I’ve contacted Virbac to see what they say.
  • “Sweet but Deadly” – this is a well written article from the S.F. Chronicle. Thanks to Tom Cushing from Border Collie Rescue of Northern California (where I found Billy) for sending this to me.
  • ASPCA Animal Poison Control Center – everybody should have this link and phone number handy at all times. From their website: “As the premier animal poison control center in North America, the APCC is your best resource for any animal poison-related emergency, 24 hours a day, 365 days a year. If you think that your pet may have ingested a potentially poisonous substance, make the call that can make all the difference: (888) 426-4435. A $60 consultation fee may be applied to your credit card.”
  • (Updated 8/20/15) Preventative Vet – Dr. Jason Nicholas in Oregon has recently taken on this topic to increase awareness. Here are some additional links:

Lessons Learned

Based on what I’ve learned, here are the recommendations I’d like to share:
noxylitol

  • The obvious one – don’t buy anything with Xylitol in it. Find some other “polyol” to sweeten your gum and other foods. And find less dog-toxic ways to maintain your oral health.
  • If you suspect Xylitol ingestion in any of your dogs, go immediately to the vet. The blood sugar drop happens almost immediately (within 30 minutes), and if you wait for symptoms, you are way past the point of simple intervention and mitigation. Billy never showed ANY clinical symptoms, yet it was clear that he was in pretty big trouble.
  • Once your dog is being treated, do your best to figure out what the actual level of consumption was. As I have mentioned, that isn’t easy to do. But it is important for determining the likelihood of liver issues, which can appear as late as 3 days after exposure and can also happen without any signs of hypoglycemia. By calculating the amount of Billy’s exposure, we were able to determine that he was below the threshold for liver damage, which saved me a couple of extra days of worry and follow-up testing (and maybe even continued hospitalization).

Conclusion

doghomeMy story has a happy ending, which I attribute to awareness, early detection, and immediate response and intervention. As I have already mentioned, the awareness and early detection were pure dumb luck. I expect Billy to live a long full life, as long as I do a better job of protecting him from my treacherous environment. And I can assure you, no more Xylitol-containing products will ever cross my threshold. Of course, I can’t control other places he might be, so I will still have to pay close attention.

Xylitol poisoning happens quickly and unexpectedly – please be vigilant for the sake of your pack.

Acknowledgements

accsonomaThanks to the terrific doctors and staff at the Animal Care Center in Rohnert Park, who treated Billy as their own and took the extra time to do additional research on Xylitol poisoning because they haven’t seen it a lot. In particular, Dr. Greg Olson, who sifted through the puke of all three dogs on Tuesday night and saw Billy through the first 12 hours of his crisis; and Dr. Laura Slater, who listened when I reported my calculations on the actual amount he ingested and found the VIN paper that allowed us to conclude that he was safe from liver damage.

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