Hydrangea Poisoning in Cats

The reason that hydrangea present a potential threat to cats is because the buds and leaves of the plant contain cyanogenic glycosides called “amygdalins”. When these glycosides are digested, they mix with water and release hydrocyanic acid inside the body. This deprives the cells of oxygen and produces a negative response in the body. The plant material can also cause skin irritation upon contact. This is especially the case in cats who have sensitive skin or skin disease.

Hydrangea, or hills of snow as it is often called, is a common garden shrub used in landscaping all over the United States. It is scientifically known as Hydrangea macrophylla of the Saxifragaceae family of plants, although it can also be called Hortensia or seven bark. Hydrangea are popular because of their large clusters of small white flowers, which can resemble balls of snow. The flowers can come in pinks, whites or blues depending on the type of plant and the pH of the soil. The plant is hardy and the flowers bloom all summer and well into the fall. 

Usually, only a mild digestive disturbance will follow the consumption of hydrangea. Severe reactions are rare but can occur. All signs to watch for are listed as follows:

• Nausea
• Vomiting
• Diarrhea (may contain blood)
• Abdominal pain 
• Depression 
• Dermatitis (in hypersensitive cats)
• Dyspnea (difficulty breathing)
• Limb stiffness
• Seizures
• Coma

Hydrangeas are very common plants found in many gardens across the country. Clippings of the showy flower clusters are often kept inside the home and used in floral decorations or bouquets. The flowers can also be dried and used as permanent decor. Both dried and fresh flowers and leaves contain the toxins that can make your cat ill. Hydrangea poisonings are rare, as a very large amount of plant material must be ingested before the body becomes overwhelmed.

If you saw your cat eating a hydrangea plant, diagnosis should be straightforward. If you are unsure if the plant was indeed a hydrangea, bring in a small clipping for the veterinarian to identify the plant. If you did not witness the cat eating any plant material, a more thorough assessment may be needed to discover what has caused the gastrointestinal distress. You may be asked to provide your cat's full medical history so that other health issues can be ruled out. You may also be asked if you allow your cat outdoors, or if you have any plants or bouquets in your home. 

The veterinarian will then perform a complete physical examination of the cat to note all symptoms that the cat is exhibiting. The vet may use a stethoscope to listen to the cat's heartbeat and breathing. In cats who are experiencing severe reactions, labored breathing may be noted. Blood samples will be taken from the cat for tests to be run. These tests generally include a complete blood count and a biochemical profile to measure the contents of the bloodstream. Urinalysis should also be used to assess how the kidneys and liver are functioning.

Treatment for cats who have ingested hydrangea is mainly symptomatic. Cases may range greatly in severity, with most being relatively mild. Serious instances may require hospitalization.

Remove Stomach Contents 

This may be done either by inducing the cat to vomit with hydrogen peroxide or by performing a gastric lavage (stomach pumping). Removing all remaining plant material from inside of the cat will prevent the body from absorbing any more toxins.

Supportive Care 

If your cat has been expelling waste for a long period of time, it may become dehydrated. Administering fluids intravenously can help bring volumes back up and stabilize body functions. The cat should be kept as comfortable as possible throughout this process.

Consuming hydrangea is generally not a life-threatening situation, although it should be taken seriously to ensure the best outcome for the cat. If the cat recovers from the illness, no lasting health effects should be seen. Keep any floral arrangements out of your cat's reach or even out of the home if they contain hydrangea. The only way to limit your cat's exposure to the common shrub is to keep it indoors where you can monitor which plants it interacts with.