Horseweed Poisoning in Dogs

Horseweed is an annual or bi-annual plant that grows in the summer throughout the state of California. Canada is its native country, and this plant can also be found in countries such as Europe, Russia, Siberia, Asia, and other countries. It thrives in all moist soil conditions. Typically, it is found on the hillsides of coastal areas and craves water for it to grow. When it is around water, it grows very quickly and tends to take over agricultural lands, landscaped properties, and other areas where the vegetation has been cut down or uprooted. Horseweed’s main habitats are within canal areas, ditches, fields of crops, vineyards and orchards, and other properties that are unmanaged.

Mature horseweed plants can grow up to 10 feet tall and spread rapidly. They contain leaves that are dark green, on long stems, and have flowers that are similar to daisies; the flowers are thin, wispy, and white and they surround a yellow center. Horseweed also resembles dandelion puffs when the flowers fall off the plant and the seeds are exposed.

The medicinal properties of horseweed have a history of being used to treat dysentery and to keep parasites away from animals. The alternate name is fleabane, which comes from the fact that it contains thymol which kills fleas.

Horseweed poisoning in dogs is a result of the ingestion of the plant, horseweed. Although reactions from the toxic agents may be mild to moderate, a veterinary visit is still necessary for dogs to effectively recover.

Symptoms of horseweed poisoning in dogs are usually mild. Symptoms after ingesting this plant may include:

• Vomiting
• Diarrhea
• Upset stomach
• Gastrointestinal discomfort

Types

There are several different names for the horseweed plant. Knowing the variety of names of this plant will give you the knowledge you need for planting on your property or allowing your dog to come into contact with it. Types include:

• Showy daisy
• Mare’s tail
• Conyza
• Canadian horseweed
• Fleabane
• Seaside daisy

Specific causes of horseweed poisoning are unknown; however, once your dog eats all or part of a horseweed plant he may have a reaction. Causes may include:

• The natural chemicals of the plant reacting with the gastrointestinal tract
• The containment of natural pest repellent
• The natural pesticide found within the plant as its defense

If your dog has ingested horseweed, call your veterinarian to have him examined as soon as possible. Your dog may be vomiting or have diarrhea at home, and if this is the case, try to get a sample of either or both. Take a sample of the plant into the veterinarian’s office with you as well as any samples of bodily fluids you are able to get. This will help the veterinarian make a faster diagnosis into rule out any other gastrointestinal conditions.

Once you take your dog to the veterinarian, he will perform a physical examination. He will administer tests such as blood work, urinalysis, biochemistry profile, and will test any samples that you may have brought in. If you were unable to bring in any samples, the veterinarian may take a fecal sample or induce vomiting. The medical professional will perform any other testing, if necessary, just to be sure there is no other condition that could be causing his gastrointestinal distress. If your dog is having severe gastrointestinal symptoms, your veterinarian may take a look in his gastrointestinal tract using an endoscope or via ultrasound.

Horseweed poisoning is typically quite mild, and once the veterinarian confirms the diagnosis of horseweed poisoning, he will begin treatment depending on your dog’s symptoms and the severity of the toxicity.

Since horseweed poisoning is typically a mild condition, treatment will be symptomatic and be dependent upon your dog’s condition. Treatment methods may include:

Emesis

Your veterinarian may induce vomiting to help rid your dog of the toxic substance contained in horseweed, which is unknown. After emesis, your veterinarian may give your dog a dosage of activated charcoal to further absorb the toxic agents from this plant.

Intravenous fluids

IV fluids help restore hydration, and help your dog with his electrolyte balances. These fluids also promote urination to further remove the toxic agent from his system.

Monitoring

If your dog had a moderate case of poisoning and experienced severe nausea, vomiting, and diarrhea from the ingestion of the horseweed plant, the veterinarian may want to keep him overnight just to be sure he is recovering nicely. The medical professional may want to keep him on IV fluids overnight and monitor his vital signs before sending him home.

Once your dog is able to go home with you, it will be important to follow any instructions given to you by the veterinarian pertaining to his after-care. Your veterinarian may also recommend a bland diet while his gastrointestinal tract returns to normal, and this may include a prescription diet, or specific foods recommended by your veterinarian that you may purchase at the store.

Once home, continue to monitor your dog for any other symptoms that may arise. If you are concerned about any of his new symptoms, give the veterinarian a call and ask him any questions if feel you need to do so.

In terms of toxic plants in or around your home, this may be the time to check for any in which your dog may come into contact with. If you are able to remove them from your home or property, please do so. If you are unable to remove them from your property, be sure to always monitor your dog when he is outdoors and keep him in an area where he is away from the toxic plants. Many dog owners that have toxic plants on the property keep their dog on a leash or in a fenced area that does not contain plants that are unsafe.