Klamath Weed Poisoning in Cats

Klamath weed contains a toxin known as hypericin, which causes photosensitivity, increased heart rate, and skin ulcers among other symptoms when ingested by cats. Photosensitivity puts your cat at a higher risk of developing sun burns, blisters, and skin cancer, so exposure to this plant—either in the outdoors or in medication—should be avoided at all costs.

Klamath weed poisoning is rarely fatal, but cat owners should still take this condition seriously. If you spot any of the symptoms of Klamath weed poisoning, take your cat to a veterinarian as soon as possible for treatment. 

Klamath weed, which is also known as St. John’s Wort, is an herb that is commonly used in herbal medications. It is believed that St. John’s Wort relieves anxiety, psychological stress, and treats depression in both humans and animals. But if you’re a cat owner, you should think twice about allowing your cat to try any supplement with Klamath weed.

The symptoms that cats exhibit after consuming Klamath weed will vary. Some cats may not experience any negative side effects after consuming Klamath weed, while others will immediately begin to exhibit some or all of the following symptoms:

• Photosensitization (sensitivity to light)
• Skin ulcers
• Blisters
• Increased temperature
• Increased heart rate

Klamath weed poisoning is caused by the exposure to the Klamath weed plant. This plant contains a toxic known as hypericin, which can cause various short-term and long-term health complications when ingested. Every part of the plant contains hypericin, but the leaves and flowers have the highest concentration of this toxin.

If you see your cat chewing on Klamath weed, or if you begin to observe some of the symptoms of Klamath weed poisoning, take him to a veterinarian as soon as possible. Try to bring in a sample or a photo of the plant so the vet can easily diagnose the condition. 

There is no test that a vet can run to confirm your cat has Klamath weed poisoning, so the majority of cases are diagnosed based on the description of symptoms from the owner. A vet can, however, perform a physical examination to get a better idea of what’s causing the symptoms. This can include examining the skin ulcers and blisters on your cat, performing basic tests such as a complete blood count and urinalysis, and using an endoscope to analyze the contents of your cat’s stomach. It’s possible the vet will be able to see plant matter in your cat’s stomach that will help him confirm the diagnosis of Klamath weed poisoning.

Treatment will begin immediately following the diagnosis. First, the vet will induce vomiting to remove the remaining plant material from your cat’s stomach. This is done by orally administering a 3% hydrogen peroxide solution. Once the vomiting has subsided, the vet may also administer activated charcoal to absorb any toxins that remain in your cat’s stomach.

The vet will also perform a gastric lavage, which is a stomach wash, to flush out any toxins that could be stuck to the cat’s stomach lining. Cats may also be given sucralfate and Kaopectin, two medications that form a paste and coat the stomach to prevent further irritation and vomiting.

If your cat has developed blisters and ulcers on his skin, the vet will need to treat these, too. Topical creams are usually applied to reduce swelling and relieve itchiness. Oral corticosteroids may also be administered in extreme conditions.

Cats may become dehydrated during the treatment due to the induced vomiting. If this happens to your cat, the vet will need to administer IV fluids until he has regained his strength.

Cats will almost always recover from Klamath weed poisoning. Most cats will be released to their owners following treatment, but if the cat is severely dehydrated from treatment, he may need to stay with the vet to be monitored.

Talk to your vet about whether or not you should make any changes to your cat’s diet over the next few days. Your cat’s stomach may be sensitive because of the treatment, so it’s sometimes recommended that you stick to softer foods while he recovers. 

Because Klamath weed poisoning causes photosensitivity, you will need to be cautious about the amount of time your cat is exposed to the sun. Photosensitive cats may develop burns on their skin much faster than other cats. To avoid this, either keep your cat indoors or consider putting clothing on your cat to protect his skin. 

If you have Klamath weed growing in your yard, remove it before allowing your cat to go outdoors.