Hops can be poisonous to at least some breeds of dogs and also sometimes to cats. The cones are the culprit when enough of them are eaten. Hops can act as an inciting cause or trigger for malignant hyperthermia but it seems the animal must have a genetic predisposition for this to occur. Caffeine can also act as a “trigger.”
Hops have been shown to trigger the reaction in susceptible dogs and cats. The triggers can induce a drastic and uncontrolled increase in oxidative metabolism, the utilization of oxygen, in skeletal muscle. This overwhelms the body’s ability to regulate body temperature. The result is high fever leading to circulatory collapse and death if not immediately treated.
The initial symptoms are restlessness, panting, abdominal pain and vomiting. In serious cases, symptoms progress into seizures, rapid heart rate and life-threatening high body temperature.
Greyhounds seem to be the most susceptible breed but also susceptible are golden retrievers, St. Bernards, Dobermans, border collies and English springer spaniels. Hops grown by aficionados pose a threat when the mature cones are low enough for the animal to reach or drop to the ground. With home-brewing becoming more popular, we could see an increase in hops poisoning. A potentially bigger threat than hops plants is dogs getting into bags of stored hops or spent, dumped hops sediment.
Dogs are far more sensitive to ethanol than humans. Even ingesting a small amount of a product containing alcohol can cause significant intoxication. No matter how popular beer- drinking dogs are on YouTube, hops poisoning is probably not a threat but intoxication from the alcohol is. Alcohol intoxication results in vomiting, loss of coordination, disorientation and stupor. Sound familiar? In severe cases, coma, seizures and death may occur. Dogs showing mild signs of alcohol intoxication should be closely monitored, and dogs that are so inebriated that they can’t stand up must be taken to your veterinarian.
Dr. David Gross of Edmonds graduated from Colorado State University’s veterinary school in 1960 and was in private practice for 10 years. He retired in 2006 as Professor and Head of Veterinary Biosciences, at the University of Illinois, Urbana-Champaign.