Most pet owners are unaware of the hazards of uncooked yeast dough when ingested by pets. When ingested by pets, uncooked yeast dough can rise and cause an obstructive foreign body in a pet’s gastrointestinal tract and can also lead to alcohol intoxication. If the dough contains yeast, there are additional potential dangers to the pet.
Yeast are microscopic fungi that use alcohol fermentation to produce energy. Baker’s yeast is the type of yeast used for baking and it includes the forms known as cake yeast, active dry yeast, instant dry yeast, and rapid or quick rise yeast. It does not include brewer’s yeast or nutritional yeast. Any uncooked dough products that contain baker’s yeast, including sourdough starters, are a potential hazard.
In the warm, anaerobic environment of the GI tract, yeast will ferment, undergoing an enzymatic process during which sugars in the dough turn into carbon dioxide and ethanol. Carbon dioxide and ethanol are responsible for causing dough to rise and also lead to expansion of dough in the stomach. In extreme cases, this can lead to gastric dilatation and volvulus (GDV), particularly in more susceptible large or giant deep-chested breeds, or even gastric rupture. Fortunately, these complications occur very rarely. As the yeast continues to ferment, ethanol is produced and rapidly absorbed, which can result in ethanol toxicosis.
Bread dough poisoning in dogs and cats mainly affects the gastrointestinal tract and neurologic system but may also result in cardiovascular and respiratory signs, as well as metabolic abnormalities. Commonly seen clinical signs may include abdominal distension, bloat, unproductive retching, restlessness, and vomiting. As yeast ferments in the stomach and increasingly large amounts of ethanol circulate in the blood, additional signs including abnormal mentation, ataxia, and vocalization may develop. Metabolic changes including hypoglycemia and metabolic acidosis may be seen. Cardiovascular collapse, respiratory arrest, coma and death may occur after ingestion of large volumes without treatment, secondary to severe ethanol toxicity and compression of the diaphragm from gastric distension. Clinical signs are typically seen within one hour after ingestion but may be delayed by several hours.
Diagnosis of bread dough poisoning is typically based on clinical signs in conjunction with a history of consumption of uncooked dough containing yeast. While there is no known toxic dose, bread dough is considered to be of moderate to severe toxicity, depending on the amount ingested.
Therapy for bread dough poisoning begins with decontamination, dogs or cats who have consumed bread dough within the past 30 minutes and are asymptomatic should have emesis induced either at home or by a veterinarian. Activated charcoal should not be used as it is ineffective for bread dough. If emesis produces all of the product ingested, the pet can be monitored at home. If only partial retrieval is evident, monitoring by a veterinarian is ideal to recognize further treatment needs. Retching with no material recovered is an emergency as it could indicate GDV. These animals should be evaluated by a veterinarian immediately.
Animals who have ingested bread dough and are showing neurologic abnormalities should not have emesis induced as this could result in further complications including aspiration or choking if vomiting occurs.
Therapy continues with stabilizing the patient. This includes symptomatic and supportive care including blood glucose monitoring, treatment with dextrose if indicated, antiemetics, monitoring of vitals, abdominal imaging and venous blood gas monitoring to identify metabolic acidosis. Intravenous fluid therapy is indicated for hypovolemic patients. Trocarization or passage of an orogastric tube may be helpful to relieve and expel gas formed during yeast fermentation . Cold water lavage to slow fermentation and gas production, decrease ethanol production, and possibly remove a portion of the bread dough may be beneficial for some patients. In severely affected patients, surgery may be indicated to remove the remaining bread dough, although most cases can be managed medically. Animals showing signs of respiratory depression may improve with the previously described treatment, however severe respiratory depression may require ventilatory support.
Because some doughs may also contain other toxic ingredients like garlic, onion, and raisins, it is important to ask owners about other potential ingredients and treat accordingly.
Fortunately, prognosis for pets who consume uncooked bread dough is typically excellent if treated early. Prognosis declines if treatment is delayed. Complications including stomach rupture or perforation often carry a poor prognosis.
Because many owners are unaware of the danger bread dough poses to their pets, this topic represents an important opportunity for client education, particularly around the holidays when home baking increases.
Kelly Mahoney, DVM student extern, University of Minnesota, Class of 2022
Heather Handley, DVM, Senior Consulting Veterinarian, Clinical Toxicology