Jump to section

What is Giant Hogweed Poisoning?

When first contacting the giant hogweed, your dog will not have any symptoms at all and this is why giant hogweed poisoning is often mistaken for other dermatitis conditions. It takes exposure to sunlight within the next few days to cause the phytophotodermatitis reaction. The topical exposure is bad enough, but this plant can also cause blindness if your dog’s eyes absorbed some of the sap. Between the pain, the huge blisters, and the swelling, that should be enough. However, the giant hogweed sap is also capable of causing blindness if it comes into contact with your pet’s eyes. The giant hogweed can reach almost 15 feet tall. Like the cow parsnip, giant hogweed has an umbrella-type flower head with hundreds of tiny white flowers.

The giant hogweed (Heracleum mantegazzianum) is often mistaken for cow parsnip, and they do look similar and cause some of the same symptoms. However, the giant hogweed symptoms are much more severe, sometimes causing disfiguring blisters that take months to heal and may leave dark scarring that lasts for years. If the sap from giant hogweed touches your dog, this can produce a disorder called phytophotodermatitis, which is a severe photosensitivity to sunlight. It is the furocoumarins (psoralens) in the giant hogweed that cause the reaction when your dog is exposed to sunlight after contact with the plant. The psoralens bind to the DNA and RNA, killing the cell membranes (skin tissue) and causing edema (swelling from fluid retention). The chemical is photosensitive, which means the rash does not show up until the affected area is exposed to strong sunlight.

Giant Hogweed Poisoning Average Cost

From 332 quotes ranging from $200 - $800

Average Cost

$400

Symptoms of Giant Hogweed Poisoning in Dogs

In the first few hours, the skin will be itchy and red, progressing to more severe symptoms within 12 hours.

  • Redness and itching
  • Black scars that can last for years
  • Photosensitization (ulcerative and exudative dermatitis)
  • Blindness (bumping into things, falling down)
  • Blistering rash that is very painful within two days
  • Light sensitivity in skin that is affected (could last for years)

 Types

Giant hogweed, or Heracleum mantegazzianum, is from the Apiaceae family in the order of Apiates and is related to, and sometimes mistaken for Heracleum maximum, known as cow parsnip. These two giant herbs look similar to each other, but the cow parsnip is shorter and has less blooms than the giant hogweed. In addition, the giant hogweed is much more toxic than the cow parsnip and the side effects of exposure are a lot worse. Some common names of giant hogweed are:

  • Cartwheel-flower
  • Giant cow parsley
  • Giant cow parsnip
  • Hogsbane
  • Wild parsnip
  • Wild rhubarb
arrow-up-icon

Top

Causes of Giant Hogweed Poisoning in Dogs

Giant hogweed contains furanocoumarins, which is a toxin that causes severe phytophotodermatitis. The sap is found throughout the entire plant, but the stems and foliage have the highest concentration of the toxin.

arrow-up-icon

Top

Diagnosis of Giant Hogweed Poisoning in Dogs

To get a definitive diagnosis for giant hogweed, your veterinarian will go by the symptoms your dog has, a skin biopsy and histology, and physical examination. A skin biopsy is a simple and painless process done by scraping the affected skin with a special tool. The veterinarian can look at the sample under a microscope and will be able to see the damaged cells. A physical examination includes body temperature, blood pressure, breath sounds, weight, reflexes, and overall coat condition. Blood work will be done for a blood count, and blood chemistry profile will be done to check the levels of bilirubin, phosphatase, gamma glutamyltransferase, and liver enzymes.

arrow-up-icon

Top

Treatment of Giant Hogweed Poisoning in Dogs

You may have already washed your dog to get rid of the sap, but the veterinarian will want to do it again with a special shampoo that will also soothe the skin. Some other parts of the treatment plan may include:

Skin care

The veterinarian will apply a steroid cream or spray for pain, inflammation, and itching. A bandage may be applied for protection from dirt and germs and the veterinarian will probably want your pet to wear an Elizabethan collar to prevent licking the area or pulling the bandage off.

Medication

Prednisone (corticosteroid) may be prescribed to reduce the pain and swelling. Oral antibiotics will also be prescribed in case of infection.

Prevention

Do not leave your dog outside unattended for a long period of time and provide plenty of shade.

arrow-up-icon

Top

Recovery of Giant Hogweed Poisoning in Dogs

Once your dog’s skin has had a case of phytophotodermatitis, that area will be sensitive to sunlight for several years. It is extremely important to protect your dog from sunlight. You can use sunblock for dogs or protective clothing and provide plenty of shade for your dog when outside. It is best to keep your dog in during the peak sun hours of 10am to 4pm if possible. Otherwise, the phytophotodermatitis may return, and leave permanent scars.

arrow-up-icon

Top

*Wag! may collect a share of sales or other compensation from the links on this page. Items are sold by the retailer, not Wag!.

Giant Hogweed Poisoning Average Cost

From 332 quotes ranging from $200 - $800

Average Cost

$400

arrow-up-icon

Top

Giant Hogweed Poisoning Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

question-icon-cta

Ask a Vet

dog-name-icon

dog-breed-icon

Golden Retriever/Chow mix

dog-age-icon

7yrs.

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Unknown severity

thumbs-up-icon

0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Unknown severity

Has Symptoms

Sever Scratching , Looks Like Hot Spot On Belly

Could this be caused from a plant . Both dogs have it and I have spent over $700.00 trying to find out what is causing the itching so bad . Have had oatmeal baths also

Aug. 7, 2020

Owner

answer-icon

Dr. Michele K. DVM

recommendation-ribbon

0 Recommendations

Thank you for your question, I'm sorry that your dogs are not feeling well. Without being able to examine them or see what's going on it is difficult to say whether a plant may have caused it, but that is not a common cause of dermatitis in dogs. If it was caused by a plant, it would probably be fairly easy to treat with antibiotics or steroids or antihistamines, and I'm not sure if your veterinarian has tried that or not. That may be something to discuss with them if not, otherwise it may be a parasite if both dogs are affected. I hope that everything goes well and they feel better soon

Aug. 8, 2020

Was this experience helpful?

dog-name-icon

Alba

dog-breed-icon

Jack Russell Terrier

dog-age-icon

2 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

thumbs-up-icon

1 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Slighty Moist Wound On Tail.

My dog has almost certainly been poisoned on his tail by Giant Hogweed - taken him to vets and they have given him Isaderm to put on the burn which seems to be more for acute moist dermatitis - advise online is for Prednisone which is a corticosteroid. Is it safe to put the Isaderm on his burn/hot spot.

July 11, 2018

Alba's Owner

answer-icon

Dr. Michele K. DVM

recommendation-ribbon

1 Recommendations

Isaderm has an antibacterial as well as a steroid in the gel, and seems quite appropriate to use with this type of injury. If you are not sure, it would be best to call your veterinarian to make sure, as they have seen Alba and know more what the wound looks like.

July 11, 2018

Was this experience helpful?

dog-name-icon

Marshall

dog-breed-icon

Border Collie

dog-age-icon

2 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

thumbs-up-icon

1 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Lesions

My guy is going through this right now, It is horrible. He is on prednisone and antibiotics for 14 days. It is on his snout just above his nose and thankfully nowhere near his eyes. It blistered so quick after first signs. 3 times in size in 24 hours.

Giant Hogweed Poisoning Average Cost

From 332 quotes ranging from $200 - $800

Average Cost

$400

How can we help your pet?