Hills of Snow Poisoning in Dogs

The hills of snow plant is a commonly seen bush or shrub that is usually about three to five feet tall and about three feet wide. It has large green deeply lobed leaves and huge white blooms shaped like balls. These can grow up to the size of a dinner plate in many cases. Although the hydrangea itself comes in many colors, the hills of snow plant has only white blooms, which is how it got its name. This plant contains cyanogenic glycoside and saponins, which are more concentrated in the foliage and blooms. The toxicity is usually limited to intestinal upset because most pets will stop eating after getting sick. However, some dogs will eat it anyway, and this can be lethal within an hour or two, so it is best to keep your dog far away from this dangerous beauty.

Hills of snow is a type of hydrangea that grows large groups of white flowers shaped like balls. This plant is common in the United States: if you have one growing in your yard, you should make sure your dog is unable to access it because it can make your pet very ill. There are two toxic materials in the Hills of Snow plant, which are cyanogenic glycoside (hydrangin) and saponins. Cyanogenic glycoside is similar to cyanide and can cause vomiting, diarrhea, and weakness if a small amount is eaten. Most dogs do not continue to eat after the intestinal upset, but if they do, it can lead to more serious symptoms, such as heartbeat irregularities, convulsions, and death. Saponins are known to cause similar intestinal tract issues as well as drooling, depression, and possible muscle spasms.

Since there are two different types of toxins, your dog may show symptoms from both, just one, or a few from each. The severity of the symptoms depends on the amount your dog ate and the health and size of your dog.

Cyanogenic glycoside

• Weakness
• Vomiting
• Diarrhea
• Heartbeat irregularities (with large doses)
• Convulsions (with large doses)
• Death (with large doses)

Saponins

• Appetite loss
• Drooling more than usual
• Nausea
• Vomiting (can be bloody)
• Diarrhea (can be bloody)
• Depression
• Weakness
• Weight loss

 Types

The hills of snow plant (hydrangea arborescens) is a type of hydrangea from the Hydrangeaceae family. There are several other names the hills of snow plant is called, such as:

• Hydrangea
• Hortensia
• Seven bark
• Snowball bush or plant

The cause of hills of snow poisoning is one or both of these toxic agents:

• Cyanogenic glycoside (hydrangin)
• Saponins

The foliage and blooms in particular can cause severe symptoms and distress if enough of the plant is ingested.

Even if you have seen no symptoms, if you believe your dog ate part of the hills of snow plant, it is best to go to the veterinary hospital or clinic right away. The effects of the cyanogenic glycoside can be fatal if enough is consumed and, while it is rare, it is still possible. If the dosage was large enough, it only takes one or two hours before it is fatal, so it is best to visit a veterinary professional for evaluation. If possible, bring a sample of the plant or a photograph to show the veterinarian. This can help with the diagnosis so your dog can get the correct treatment. Take your pet’s medical record with you as well, if you have it. If not, be sure to let the veterinarian know if your dog is on any medication or has been ill recently.

A physical examination will be done to check your dog’s temperature, weight, reflexes, blood pressure, heart rate, breath sounds, and coat and skin condition. In addition, a urine and stool sample may be taken for microscopic evaluation and to check for infections. Other laboratory tests needed are usually a complete blood count (CBC), blood chemistry, glucose levels, liver panel, and blood urea nitrogen (BUN). Additionally, abdominal radiographs (x-rays) will be done so the veterinarian can check for blockages or plant particles still in your dog’s system. If a more detailed view is needed, an ultrasound, CT scan, or MRI may be performed.

The treatment for poisoning is usually the same as with other poisonous plants, but with cyanogenic glycoside toxicity there is an antidote that can be effective if it is given in time. If your dog ate more than just a small amount, the veterinarian can use sodium thiosulfate, sodium nitrite, oxygen, and fluid therapy. If your dog is still doing fine and it has been more than two hours, chances are good that a lethal dose was not eaten, but the veterinarian may want to keep your pet overnight for observation.

Emesis, Charcoal, and Gastric Lavage

If just a small amount was consumed, your veterinarian may decide to give your dog a peroxide solution or ipecac to induce vomiting and activated charcoal to absorb any leftover toxins. If your veterinarian thinks it is necessary, a gastric lavage can be done as well, using warm saline solution to rinse the plant residue from your dog’s intestinal tract and stomach.

If your pet received treatment within two hours or if your dog did not eat a lethal dose, you should be able to take your pet home right away. It will not be long before your dog is back to normal. However, if your dog ate a lethal amount and treatment was not started within two hours, the chance of survival is grave. Most dogs do not make it past the first two hours.