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Hops
Plant Name:
Hops
Scientific Name:
Humulus lupulus
Family:
Cannabidaceae
Toxins:
Unknown
Poisoning Symptoms:
Malignant hyperthermia (body temperature in excess of 105?F/40.6?C, normal canine temperature is 101-102.5 ?F /38-39.2°C), rapid shallow breathing, tachycardia (racing heart rate), anxiety, vomiting, clotting abnormalities, and even death. Other reported symptoms include abnormal behavior, heightened aggression, colic, abdominal pain, congestion of the oral mucous membranes, hypersalivation, dyspnea, excitement, flatulence, hypersensitivity to light, sound, external stimuli; pain on external abdominal pressure, red or brown urine, seizures, collapse. In the absence of treatment death has occurred in less than 6 hours for severely intoxicated dogs.
Additional Information:
Humulus lupulus (common hop or just hop) is a species of flowering plant in the Cannabaceae family. Originally native to Europe, western Asia and North America, the plant can now be found throughout the world due to its widespread use as the main ingredient in the production of many beers. In botanical terms the plant is considered to be a dioecious, perennial, herbaceous climbing plant that sends up new shoots in the early spring, dying back to a cold-hardy rhizome in autumn. In layman’s term, it has distinct male and female portions, lives more than two years and dies off to ground level at the end of each growing season. A long plant, in the wild it can reach lengths of 18-24 feet and in cultivation can grow as long as 40 feet, though technically it is a bine rather than a vine, as it uses its own shoots to act as supports for new growth. The plant usually flowers between July and August and the fruit cones ripen between September and October; only the female plants produce flowers that become fruit cones.
The species is a main ingredient of many beers, as such it is widely cultivated for use by the brewing industry . The fragrant flower cones of the hop vine (hops) impart bitterness and flavor, and also have preservative qualities. The extract is antimicrobial, which makes it useful for making natural deodorant. Hop contains myrcene, humulene, xanthohumol, myrcenol, linalool, tannins, and resin. The exact toxic principle, however, is unknown, but may be related to essential oils, resins, phenolic compounds, or nitrogenous constituents within the plant. The greatest threat to pets is not posed by the fact that the plant can be found growing in the wild, nor the fact that it is used by commercial breweries, but it is its widespread use by homebrewers that creates the greatest opportunity for a pet poisoning scenario.
As of 2012, the American Homebrewers Association estimated that there were over 1,000,000 active homebrewers in the United States. Among the essential ingredients for homebrewers is “hops” which is used in the form of dried buds, concentrated pellets or hops plugs; all of which are poisonous to pets (hops plugs are generally considered to be the most toxic). The most common victim is dogs, and to a much lesser extent cats. Intoxication is usually the result of a pet gaining access to areas containing unsecured raw materials for making homebrews. To date there have only been a handful of reported pet poisoning cases involving hops. As a result most veterinarians will have no experience identifying or dealing with the intoxication of a pet by hops.
In the vast majority of cases, the initial signs of hop poisoning include malignant hyperthermia (body temperature in excess of 105?F/40.6?C, normal canine temperature is 101-102.5 ?F /38-39.2°C), rapid shallow breathing, tachycardia (racing heart rate), anxiety, vomiting, clotting abnormalities, and even death. Other reported symptoms include abnormal behavior, heightened aggression, colic, abdominal pain, congestion of the oral mucous membranes, hypersalivation, dyspnea, excitement, flatulence, hypersensitivity to light, sound, external stimuli; pain on external abdominal pressure, red or brown urine, seizures, collapse. In the absence of treatment death has occurred in less than 6 hours for severely intoxicated dogs. As is the case with many other toxins, size and breed may play a factor in the severity of the intoxication. Although any breed may be affected, breeds with a predisposition for malignant hyperthermia (e.g. Labrador Retrievers, St. Bernards, Greyhounds, English Springer Spaniels, Border Collies, Pointers and certain northern breeds) are at a higher risk. Likewise smaller dogs are at an increased risk for severe intoxication as their smaller size means less needs to be ingested to suffer a potentially lethal intoxication.
First Aid:
The prognosis for animals that have ingested Humulus lupulus or one of the various forms of hops used as an ingredient in the beer making process is going to depend on the amount that was ingested relative to body size and the time that elapses from consumption to treatment. Prompt veterinary intervention is necessary to prevent death in severely intoxicated animals. Clinical signs of hops intoxication will typically develop within one hour of ingestion, but may be delayed as long as several hours. This unfortunately means that a dog could eat a potentially fatal amount and function normally for a few hours giving the body a chance to fully absorb large amounts of the toxin. When the animal finally does begin to show clinical signs of poisoning its condition may then rapidly go from bad to worse, leaving little time to make a diagnosis and in many cases not enough time to begin the appropriate treatment. In five reported cases of severe intoxication involving canines from the European National Animal Poison Control Center, only one survived. In cases where a large amount of the plant has been ingested the time between the onset of symptoms and death can be as short as a few hours or delayed as long as a few days. In simplest form this means that many animals are destined for a fatality by the time signs present and many may die before being seen by a veterinarian to institute treatment.
In cases of a witnessed ingestion where only a small amount of the plant may have been consumed it may be possible to avoid serious complications by quickly inducing vomiting. This can be accomplished by giving an emetic such as 3% hydrogen peroxide orally at a dose rate of 1 teaspoon per 10 lbs of body weight. After vomiting, the mouth should be rinsed and flushed thoroughly with water. Once symptoms start, however, it is important that the animal be treated by a veterinarian. The most significant symptom being malignant hyperthermia which can result in damage to and the failure of multiple organ systems as the body superheats (often to temperatures in excess of 108 degrees Fahrenheit). Depending on the amount of time that has elapsed, veterinary treatment will likely start with gastric lavage and the administration of activated medical charcoal to both purge and neutralize the toxin. As the charcoal passes through the digestive system, toxins are trapped in the charcoal so that when the charcoal passes from the patient, the toxins are expelled as well.
From this point treatment is largely symptomatic and supportive as there is no specific antidote for hops intoxication. Attempts should be made to treat the malignant hyperthermia with cold water baths to mitigate secondary conditions such as metabolic acidosis, cardiac abnormalities, electrolyte imbalances and rhabdomyolysis. In the event that symptoms continue to worsen; IV sodium bicarbonate may be used to reverse metabolic acidosis, rhabdomyolysis may be managed with the administration of calcium to protect against cardiac complications, insulin or salbutamol to redistribute potassium into cells, and infusions of bicarbonate solution. At this stage it is likely that irreversible damage has already occurred to one or more vital organs making euthanasia the only remaining option. Prevent further ingestion of the plant and seek veterinary care.
Species Affected:
Toxic To Dogs
