Xylitol Toxicity

Happy (almost) Easter! This weekโ€™s posts are going to be themed around toxins commonly seen around the Easter holiday. Todayโ€™s path rounds are on ๐ฑ๐ฒ๐ฅ๐ข๐ญ๐จ๐ฅ ๐ญ๐จ๐ฑ๐ข๐œ๐ข๐ญ๐ฒ!

๐–๐ก๐š๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐—๐ฒ๐ฅ๐ข๐ญ๐จ๐ฅ is an artificial sweetener found in candies, peanut butters, baked goods and gum. It can also be found in other products like chewable vitamins, some medications, toothpastes, etc.

๐–๐ก๐จ ๐ ๐ž๐ญ๐ฌ ๐ข๐ญ?
Dogs seem uniquely susceptible to xylitol toxicity!

๐–๐ก๐š๐ญ ๐œ๐š๐ฎ๐ฌ๐ž๐ฌ ๐ข๐ญ?
Xylitol causes release of large amounts of ๐ข๐ง๐ฌ๐ฎ๐ฅ๐ข๐ง, which is the major hormone that encourages ๐ ๐ฅ๐ฎ๐œ๐จ๐ฌ๐ž (sugar) in the bloodstream to enter cells. With large amounts of insulin floating around, more glucose than normal is pushed into the cells, resulting in ๐ก๐ฒ๐ฉ๐จ๐ ๐ฅ๐ฒ๐œ๐ž๐ฆ๐ข๐š (low blood sugar). Xylitol can also cause severe ๐ก๐ž๐ฉ๐š๐ญ๐ข๐œ ๐ง๐ž๐œ๐ซ๐จ๐ฌ๐ข๐ฌ (cell death in the liver), however the mechanism of this is unknown.

๐–๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐š ๐ฉ๐ซ๐จ๐›๐ฅ๐ž๐ฆ?
Hypoglycemia can cause ๐š๐ญ๐š๐ฑ๐ข๐š (irregular, wobbly gait), seizures, and even a coma. This is due to the nervous systemโ€™s requirement for glucose to produce energy, whereas other types of cells can use proteins or fats if glucose is limited. Without enough glucose in the blood, the nervous system quickly develops issues!

The hepatic necrosis caused by xylitol can lead to ๐ข๐œ๐ญ๐ž๐ซ๐ฎ๐ฌ (yellowing of the skin), vomiting and ๐œ๐จ๐š๐ ๐ฎ๐ฅ๐จ๐ฉ๐š๐ญ๐ก๐ฒ (inadequate blood clotting). The liver is responsible for producing most of the clotting proteins in the blood, so when it fails, it stops producing these proteins. Affected animals may be at risk of excessive bleeding or even spontaneous bleeding.

๐‡๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐š๐ ๐ง๐จ๐ฌ๐ž๐?
Diagnosis is typically made through a history of xylitol ingestion, combined with findings of hypoglycemia or liver injury on bloodwork.

๐‡๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐ž๐š๐ญ๐ž๐?
Patients with hypoglycemia are typically given supplemental glucose until they are able to maintain their blood glucose concentration on their own. If liver disease or coagulopathy develops, these will need to be treated as well, usually though administration of ๐ฉ๐ซ๐จ-๐œ๐จ๐š๐ ๐ฎ๐ฅ๐š๐ง๐ญ๐ฌ (encourage blood clotting) and ๐ก๐ž๐ฉ๐š๐ญ๐จ๐ฉ๐ซ๐จ๐ญ๐ž๐œ๐ญ๐š๐ง๐ญ๐ฌ (protect against liver damage).

๐๐ก๐จ๐ญ๐จ๐ฌ
1-2) Examples of icterus in the ear and gums from a dog with hepatic necrosis.
3) The abdomen of a dog with hepatic necrosis showing multiple small, spontaneous hemorrhages called ๐ž๐œ๐œ๐ก๐ฒ๐ฆ๐จ๐ฌ๐ž๐ฌ.
4) The liver of that dog! The darker patches are likely areas of hemorrhage, interspersed with sad, dying liver cells.
5-6) What that liver might look like on histology! The darker red areas have hemorrhage overlying dead liver cells, while the more pink areas are liver cells that are still alive.

๐’๐จ๐ฎ๐ซ๐œ๐ž๐ฌ
Gwaltney-Brant SM. Xylitol toxicosis in dogs. Merck Veterinary Manual 2021.

Photos 1-4 ยฉ University of Calgary Diagnostic Services Unit.
Photos 5-6 ยฉ Noahโ€™s Arkive contributor Miller licensed under CC BY-SA 4.0.

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