The complexity of the liver has been widely celebrated in literature. Take Yossarian from the novel Catch-22, who recognized that this vital organ is so important and yet so poorly understood that false complaints about it could be used for malingering.
Fortunately, medical science has made significant progress toward understanding the liver. Some of the poisons that affect it, however, remain mysterious in their mechanisms of action.
The liver plays a number of important roles in the body. It serves as the storehouse of glycogen, which it converts into blood sugar when needed. It is involved in the collection and release of bile, which aids in digestion. It is the source and target of many hormones and peptides that regulate essential body functions. And, crucially, it is the body’s first responder to toxins.
Most toxins enter the body by way of the mouth. After they are swallowed, they go to the gastrointestinal tract. It is the job of the gastrointestinal tract to digest and then absorb ingested material into the bloodstream. Because potential toxins are plentiful in the environment, blood that has passed through the intestinal tract to pick up nutrients next flows directly to the liver. One of the liver’s crucial jobs is to metabolize or inactivate any toxins that come its way. It then passes them to the kidneys for removal from the body.
The liver does an amazing job of inactivating ingested toxins ranging from alcohol to pesticides to bacterial enterotoxins. However, its job on the front lines of detoxification places it at substantial risk. The liver itself is susceptible to some toxins. If your dog ingests them he can suffer from catastrophic consequences.
The July/August issue of the Journal of Veterinary Emergency and Critical Care (JVECCS) included an overview of some of the most dangerous toxins that can cause a dog’s liver to fail. What follows is a list of some of the most clear and present dangers to your dog’s liver.
This artificial sweetener has grown ever more common over the past several years. It is popular because it tastes like sugar, does not promote diabetes, and is purported to prevent dental disease in people. Unfortunately, it is dangerously toxic to dogs.
Xylitol has the potential to kill dogs in two ways. When a dog consumes a pack of sugarless gum containing xylitol (for now the most common means of exposure), the product is absorbed into the bloodstream by the intestinal tract. The dog’s body mistakes the xylitol in the blood for real sugar, and is tricked into acting as if blood sugar is too high. The body responds by releasing insulin, a hormone that reduces blood sugar.
The real sugar levels in the bloodstream subsequently drop to dangerously low levels. Seizures, coma, and death may occur. But it gets worse.
If the toxicity is recognized and treated early, blood sugar levels can be supported with continuous intravenous dextrose (sugar) administration. One to three days later, however, liver failure can develop.
The cause of liver failure is not understood. It may be due to stress related to the liver’s role in blood sugar regulation, or xylitol may be converted into a product that is dangerously toxic to the liver. Liver failure from xylitol has the potential to be fatal.
Xylitol exposures, in my experience, are rapidly increasing. Cases of xylitol exposure are now as common as exposures to very prevalent toxins such as grapes, chocolate, and marijuana. But xylitol is much more serious than any of the others. Most dogs will survive grape and chocolate ingestion if they receive treatment, and almost all dogs will survive marijuana exposure even if they aren’t treated. Xylitol has the potential to kill dogs even if they are treated.
Here is the big problem: Xylitol is showing up in all kinds of products these days. It traditionally has been found in sugarless gums and candies. But now it also is a regular addition to over-the-counter and prescription medications. It can be found in food items ranging from ice cream to chocolate (talk about a double whammy — let us pray that raisins coated with xylitol chocolate never are released). Some dog toothpastes even are purported to contain the stuff.
Perhaps most disturbingly, some brands of peanut butter now are being formulated with xylitol. Given the frequency with which peanut butter is used as a treat in dogs, I cringe when I think about what this portends.
I realize that sugar has had a long and atrocious history, ranging from its role in slavery to its roles in dental disease and obesity. But if you own a dog, I assure you that it is better than xylitol. Be diligent and banish xylitol from your home. And only buy natural organic peanut butter.
These beautiful decorative plants thrive indoors and also are common outside in warmer areas. Every portion of the plant is poisonous when eaten, but the seeds are especially dangerous.
Early symptoms of sago palm toxicity include vomiting, poor appetite, and diarrhea. Some dogs may experience disorientation, behavior changes, or seizures. One study found that half of dogs who consumed sago palm died of liver failure.
There is no specific treatment for sago palm toxicity. The best option is prevention. Dog owners should not have sago palms in their homes. A leash, combined with situational awareness, is the best way to prevent sago palm exposure outside.
As the owner of a Labrador Retriever, the menace of blue-green algae always is on my mind. My pal Buster loves to swim, and he consumes copious water when he engages in this activity.
Blue-green algae grows in shallow stagnant warm water. Symptoms of toxicity can occur within one hour of swimming, and there is no antidote. The threat from blue-green algae is not merely academic; last month public health officials in Sonoma County, California, recommended that no dogs swim in the Russian River after a pet died from algae exposure.
Death cap mushrooms
Algae season may be winding down, but mushroom season is about to begin in California. Amanita phalloides exists but is rare throughout North America. It is more common in Europe, and it is quite common in some areas of the United States, such as the Bay Area in which I reside.
The common name for this mushroom says it all: death cap. It’s curtains if your dog eats one.
Death cap mushrooms bear an uncanny resemblance to paddy straw mushrooms, which are edible, delicious, and common in Asia. Every few years someone stumbles upon one in California, mistakes it for a paddy straw, and includes it in a soup that is served to the family. Everyone who eats the soup gets sick; those who do not receive liver transplants die.
Keep your dog on a leash, be aware of your surroundings, and never let your dog eat wild mushrooms. If your dog manages to get ahold of a wild mushroom, do your best to collect a sample of the specimen and rush to the vet. Your vet or a poison control center may have access to mushroom experts who can identify the fungus and help devise a plan of action. Death caps like to grow around oak trees, so try not to walk your dog near oaks during the wet season.
In general the best way to protect your dog from liver poisons and many other hazards is to be educated and vigilant. And to banish xylitol from your life.
Read more from the Ask a Vet series:
- Ask a Vet: Is Frontline Plus Still Working?
- These Common Seasonal Dangers Can Threaten Your Dog
- Ask a Vet: What Causes Sudden, Continuous Snorting in Dogs?
Got a question for Dr. Barchas? Ask our vet in the comments below and you might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)