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Cape Town - A popular sweetener among diabetics and those wanting to lose weight has been found to be deadly to dogs and birds.
Xylitol is a sugar alcohol used as a sweetener in baked products, chewing gum, toothpaste and lozenges.
But vets have warned people to keep their pets away from it.
On Easter Sunday, a 10-year-old Chihuahua, Pip, in Fort Collins, Colorado, died after eating apple pie baked with xylitol.
The owner’s vet said that while the sweetener was safe for humans, it could lead to pancreas and liver failure and even seizures if eaten by animals.
It appears that xylitol is also toxic for wild birds.
Joburg vet Dr Brett Gardner examined the bodies of 30 Cape Sugarbirds that had died within 30 minutes of drinking a solution made with xylitol, from a feeder in a Hermanus garden.
The homeowner had bought the xylitol for a diabetic family member and was unaware it was toxic for birds.
When the birds dropped dead he contacted CapeNature, which sent the carcasses and the solution to the Johannesburg Zoo where Gardner examined them and concluded that xylitol was the likely culprit.
Gardner suspects the xylitol triggered a huge insulin release, causing an irreversible drop in blood sugar.
He believes it is the first case of xylitol intoxication reported in a wild bird.
Because the product had only become popular in the past few years he had not been able to trace any other reported cases of poisonings in birds.
“There have been some studies on its |use in poultry and there it resulted in |poor growth. In some studies done on nectar preferences it has been shown that nectar-feeding birds avoid nectar containing xylitol.”
But there had been a fair amount of case reports of xylitol toxicity in dogs in the US and it had recently been identified as an emerging toxicity.
“In dogs it has been ingested via xylitol containing sugar-free gum and used as a diabetic sugar in baked goods (and the like). I even saw some ice cream being sold as healthy low-carb containing xylitol.”
Gardner intends writing a continuing professional development article for vets |on xylitol toxicity and is documenting |the sugarbird case for an avian practitioner’s journal.
In Cape Town a number of vets already warn their clients about the potential |dangers.
Dr Cathy Wahl, of Kloof Vet in Green Point, said accidental poisoning of pets from xylitol can happen if someone has used it as a sweetener in their own food and put the leftovers down for their pets.
People also mistakenly believe that because it is safe for humans it is safe for pets.
There is not much information available on toxicity in cats but there are many reports of such poisonings in dogs since they |are more likely to pinch treats containing|xylitol.
Ingestion of xylitol in dogs, unlike in humans, leads to the release of high levels of insulin which leads to hypoglycaemia (low blood glucose) causing weakness, disorientation and, in severe cases, seizures.
Long-term liver necrosis can result and lead to liver failure and death.
CASE STUDY BY DR GARDNER
Early in January last year, approximately 30 Cape sugarbirds ( Promerops cafer) were found dead in a garden in Voëlklip, near Hermanus.
The property owner contacted CapeNature staff, who had the foresight to preserve the carcasses so post-mortem examinations could be performed.
The frozen birds were sent to the Johannesburg Zoo in Gauteng.
Luckily, a frozen sample of the nectar from the bird feeder was also submitted, along with the package details of the sugar used in the nectar solution.
After careful examination of the birds, together with observers’ accounts of the birds after they visited the feeder containing a concentrated xylitol solution, and ruling out all other obvious causes of death, we concluded the most likely cause of death was xylitol toxicosis.
Generally, flowers offer one of three nectar sugars as rewards for pollination: glucose, fructose and sucrose.
Within the southern African Proteaceae, a family of plants on which Cape sugarbirds are highly dependent, only two genera have been shown to produce small to moderate amounts (1 to 39 percent) of xylose in their nectar. Xylose is absent from the nectar of the remaining 14 genera.
Xylitol has recently become popular as an ingredient in human foodstuffs, often as part of low-carbohydrate or diabetic diets. As its use spreads, an increasing number of cases of toxicity are being reported in dogs and other species. In dogs, xylitol causes an enormous stimulation of the pancreas and release of insulin.
To the best of my knowledge, this is the first case of xylitol intoxication reported from a wild bird.
What we suspect may have occurred with these birds is that ingesting a highly concentrated solution of xylitol triggered a massive insulin release, causing an irreversible drop in blood sugar.
The sugarbirds apparently started exhibiting signs of distress within 30 minutes after drinking the xylitol nectar.
I therefore cannot recommend strongly enough that readers never include xylitol in any nectar or other food source offered to birds.
Furthermore, I urge any readers who are aware of similar cases to e-mail me at [email protected]
* This article was published in the latest edition of African Birdlife.
* Dr Brett Gardner is a veterinarian based in Joburg.