Bishop's Weed Poisoning in Cats

Many common plants in your garden or yard, or in the local park, may look harmless and even have an attractive flower or scent. While these may even be harmless to humans, many plants can be harmful or toxic if ingested by your cat. Bishop’s weed is an attractive green plant with white flowers that also goes by the names bishop's flower, bishop’s weed, false bishop’s weed, bullwort, greater ammi, false Queen Anne's lace, and laceflower. This plant can be commonly found in gardens and growing wild. Ingestion of this plant by your cat can cause severe reactions. If you believe your cat has ingested bishop’s weed or any other poisonous plant, you should seek immediate veterinary attention.

Bishop’s weed poisoning can cause a variety of symptoms, varying in severity depending on the amount of the plant consumed and your cat’s general health and body weight. Common symptoms of bishop’s weed poisoning include:

• Photosensitization (sensitivity to light that causes burning or ulceration of the skin)
• Ulcers or open wounds on skin of ears, muzzle or vulva
• Blindness
• Cloudy corneas
• Photophobia or visual sensitivity to light
• Irritation and burning of the mouth, tongue and lips
• Vomiting
• Excessive drooling

Bishop’s weed is one of many plants that can prove toxic to your cat if ingested. Bishop’s weed has white, lace-like clusters of flowers at the ends of one to two foot long stalks. 

The toxic chemicals in bishop’s weed are insoluble calcium oxalates and furanocoumarins. Furanocoumarins cause severe photosensitivity in your cat’s skin. When your cat is exposed to sunlight after bishop’s weed poisoning, their skin can burn excessively. This will cause minor irritation in some animals up to severe ulceration. In some cases, these ulcers may become infected, causing additional complications.

The sensitivity to light infects all of your cat’s external structures, including their eyes. When exposed to bright sunlight, cats suffering from Bishop’s weed poisoning may suffer permanent damage to their corneas, including potential blindness in severe cases.

In cases of suspected poisoning, a rapid and accurate diagnosis is vital for the long-term health and recovery of your cat. Your vet will begin by thoroughly examining your cat including their mouth, paws and exposed belly since these areas are the most prone to contact and will show the immediate effects of poisoning. 

While it may be obvious that your cat has ingested a toxic substance, it may be difficult to identify the exact plant or chemical your cat has come in contact with. If you witnessed your cat eating a particular plant, you should carefully bag up a sample and bring it with you to your veterinarian’s office. This will help your vet determine the best course of treatment. 

Your vet may also collect a blood sample to send away for laboratory analysis. This will help rule out other conditions and may also confirm that the internal organs have not been damaged by the toxins.

Treatment of bishop’s weed poisoning in your cat is similar to the treatment for poisoning of other types. First, your vet will work rapidly to eliminate any remaining material from your cat’s system. This is done by forcing your cat to vomit and retch. Your vet may administer a solution of water or other fluid with a small amount of hydrogen peroxide. It is important that pet owners not try this procedure at home without instructions from an experienced vet, as peroxide on its own can be dangerous to your cat.

Next, your vet may administer a substance called activated charcoal. This is done by inserting a tube directly into your cat’s throat and using a needleless syringe to force the charcoal solution into the stomach. Activated charcoal will absorb a large number of toxic substances and then pass through your cat’s system undigested, helping prevent additional poison from getting into your cat’s system.

After your cat is stabilized, your vet will also lavage, or rinse out, your cat’s mouth, eyes, and other affected areas. Your cat will need to stay under strict veterinary care until their vital signs are stable enough for them to return home.

If quick treatment is sought, most cats recover well after bishop’s weed poisoning. Your cat will need to be kept indoors away from excessive light for a period of time until the poison has been metabolized and is eliminated from your cat’s system. Your cat will need a follow-up vet visit to check on their organ function and to ensure they are not suffering any additional side effects. With proper care, your cat should be able to make a full recovery.