Hops Poisoning in Dogs

Humulus lupulus or hops is a member of the Cannabaceae family. The cone-like flowers found on the female plant have a bitter flavor when dried and are traditionally incorporated into the beer making process, both commercially and at home. Hops are also occasionally used as a calming agent in herbal teas and supplements. The hops plant has been found to be extremely poisonous to dogs. Although the exact mechanism of toxicity has not been identified, all versions of the plant seem to be toxic, sometimes even in small doses. Instances of poisoning have become more common with the increased popularity of home brewing.

Hops can be dangerous both before and after they are used in the brewing process, however dry uncooked hops are very bitter and less likely to be eaten by a dog. Used hops that have been boiled with the beer have a much better flavor and this can cause a problem for dogs if the hop residue is improperly disposed of or left to decompose on a compost heap. Malignant hyperthermia is the most common symptom of toxicity; this is marked by a rapid increase in body temperature, heavy breathing, and restlessness. Normal body temperature for a dog is around 101-102.5 ⁰ Fahrenheit (38.3-39.2⁰ Celsius), but with hops toxicity it can rise quickly above 105 or even 108 ⁰ Fahrenheit (40.6 ⁰ or 42.2 ⁰ Celsius). With large doses, vomiting and abdominal pain will also be present, and dogs may have seizures and abnormal blood clotting. Without treatment, death can occur in as little as six hours after ingestion. Some studies have found that rigor mortis sets in quickly and suddenly after death. Breeds that are prone to malignant hyperthermia are believed to be more likely to develop severe hops toxicity, however the problem could occur in any dog.

Hops flowers are used to flavor beer during the brewing process. They can be extremely toxic to dogs and large amounts can quickly cause death. This is called hops toxicity. It has become more common with the increased popularity of home brewing.

These are the symptoms that could indicate your dog has eaten hops. Hops poisoning should be treated as an emergency.

• Heavy panting
• Anxiety
• Increased body temperature (higher than 105⁰ F or 40.6 ⁰ C)
• Rapid heartbeat (tachycardia)
• Vomiting
• Abdominal pain
• Flatulence
• Seizures

Types

These are the types of products that could be a problem for your dog.

• Hops plugs – whole flowers that have been dried and compressed, generally found to be the most toxic
• Hops pellets – powered and processed hops
• Whole leaf hops – dried flowers that are not compressed
• Hops extract – concentrated liquid used as flavoring
• Hops tea – medicinal herbal tea
• Herbal creams that contain hops

These are some of the factors that increase the risk of hops poisoning.

• More severe in some breeds
• Greyhounds, Labrador Retrievers, Saint Bernards, Pointers, Dobermans, Border Collies, English Springer Spaniels, Golden Retrievers, mixed breeds
• Dry hops left in an accessible area where dogs can chew through the bag
• Used hops (trub) left unattended
• Used hops dumped on a compost heap
• Used hops left in a dog accessible trash can
• Improper disposal of hops tea leaves or medicinal products

The veterinarian will diagnose hops poisoning based on the symptoms and a history of hops ingestion. Dogs with hops toxicity will have a very high body temperature as well as signs of metabolic acidosis on a blood test. The veterinarian will try to rule out an infection or another condition that could be causing your dog’s symptoms. If you know your dog could have access to hops, either through your own or a neighbor’s home brewing, this will help with diagnosis. Breed can also be relevant as some dogs may be more prone to developing serious hops toxicity. If your dog ingested something from the garbage and you are unsure what it is, you should bring a sample with you for the veterinarian to identify.

Immediate treatment will be necessary to save your dog’s life, especially if a large amount of hops was ingested. For recent poisoning, vomiting may be induced or the veterinarian may perform gastric lavage under anesthesia. Activated charcoal may be given to reduce absorption in the stomach. Several medications are used to stabilize the body temperature with malignant hyperthermia, either Dantrolene or Cyproheptadine. Intravenous fluids and electrolytes may be necessary to balance metabolic acidosis, and diazepam may be given to reduce seizures. Enemas can also help to flush toxins out of the intestine.

Your dog may recover from a mild exposure, but severe hops toxicity does not have a good prognosis, even with immediate treatment. Prevention is more successful than treatment, so limiting your dog’s access to hops is the best way of managing the condition. Any used hops should be double bagged and placed in a sealed dog-proof garbage can. Disposing of used hops as garden mulch or compost can endanger any dog in the neighborhood so this should be strictly avoided. Prior to use, hops should also be kept in a sealed plastic container rather than a bag. It’s important for any home brewer to be aware that this product is very dangerous for pets and take the necessary precautions. There is no known safe dose of hops for dogs, so caution should be taken even with teas or herbal supplements. These products should also be carefully disposed of and kept out of reach of dogs.