Cats are obligate carnivores, which means their diet must consist of meat to survive; however, many cats also enjoy a selection of plants, many of which can induce a short high when bruised or ingested. The reason for this is because plants contain allomones which are chemicals that protect the plant from insect herbivores (insects that feed on plants) or attract predators of insect herbivores. They are secondary metabolites, not responsible for the growth of the plant, but serve to protect it.

The most well-known is caffeine, which is found in the coffee plant, and let’s not forget theobromine, which is found in the cacao plant. These chemicals are toxic to small plant-eating insects, but many are also attractive to cats, stimulating an olfactory response.

One recent study of big cats found cats who did not respond to catnip may respond to Tartarian honeysuckle, valerian root or silvervine and a lucky 23% responded to all four plants. None of the above plants contains nepetalactone, but do have similar compounds.

1. When the chemical enters the cat’s nasal passages, it binds to olfactory sensory neurons in the olfactory epithelium (specialised tissue at the back of the nose), which is involved in smell. A layer of mucus covers the olfactory epithelium which traps odour molecules.
2. The olfactory sensory neurons send signals through the olfactory tract to the olfactory bulb, which is located in the front part of the brain and responsible for processing smells.
3. The olfactory bulb then sends signals to several regions of the brain, including the amygdala (responsible for emotions) and the hypothalamus (responsible for behavioural responses).

The plants listed in this article are safe for cats to ingest, and will not cause long-term harm to cats.

Terpenes that attract cats

• Nepetalactone
• Actinidine
• Dihydronepetalactone
• Epinepetalactone
• Neonepetalactone
• Isodihydronepetalactone
• Isoiridomyrmecin
• Mitsugashiwalactone
• Onikulactone
• Iridomyrmecin
• Boschnialactone
• Actinidiolide
• Dihydroactinidiolide
• Boschniakine

How do cats respond to these plants?

When experiencing a high, cats will drool, roll, and rub their face and cheeks on nearby objects. The effects usually last for 5-10 minutes.

These behaviours are similar to that of a cat in heat, and it is thought that the chemicals are similar to sex pheromones.

Catnip:

The most well known of plants which cats enjoy.  A member of the mint family, the active ingredient is nepetalactone, which induces a state of euphoria in cats. Catnip also contains other chemicals which are attractive to cats, including epinepetalactone and dihydronepetalactone.

Approximately 60% of cats respond to catnip; however, it does not affect kittens. All parts of the plant can be sniffed or ingested to induce a high.

How to give: 

Catnip can be given to cats fresh or dried.

Where to buy:

Fresh catnip plants or seeds can be purchased from most garden centres. Dry catnip is available from pet shops.

Tartarian honeysuckle

Out of the 180 species of honeysuckle, only the Tartarian honeysuckle (Lonicera tartarica) affects cats. It is the wood of the plant which induces a high; however, the berries and flowers can be toxic if ingested. One study found that 50% of cats (out of a sample of 100 cats) responded to Tartarian honeysuckle.

How to give:

Be careful when giving Tartarian honeysuckle wood to cats as it can splinter in the mouth and/or cause damage to the gastrointestinal tract. Grate into sawdust.

Where to buy:

Some specialty stores stock Tartarian honeysuckle for cats which comes in sawdust form.

Cat thyme

Image courtesy Leonora (Ellie) Enking, Flickr.

Despite the name, cat thyme (Teucrium marum) is not related to the common thyme herb used in kitchens but is a close relative of germander. A low growing, perennial shrub with a musty aroma, cat thyme is native to the Western Meditteranean.

How to give: 

Either plant some in your garden or in a pot for your cat to enjoy or dry and sprinkle on toys and scratching posts.

Where to buy: 

Select garden centres or online stores.

Silver Vine

Other names: Matatabi, Japanese catnip

A deciduous vine native to mountainous regions of China and Japan, silver vine (Actinidia polygama) induced a response in 80% of cats tested in the same test linked to above. The active ingredients are actinidine and dihydroactinidiolide.

How to give:

Silvervine comes in many forms for cats, in sticks, seeds, flowers, and leaves. Sprinkle dry seeds, flowers, and leaves on toys or scratching posts. Avoid sticks that can get stuck in the mouth or splinter, grate into sawdust and sprinkle onto toys or if you are crafty; you can add all of the above plant parts to the inside of homemade toys.

Where to buy: 

Select garden centres.

Valerian root

This plant is commonly used in humans as a sleep aid, but in cats, it has the opposite effect. The active ingredient is actinidine, which is also found in silvervine. It is the roots of the plant which induce the high.

How to give: 

Only give the root, and don’t use valerian supplements for humans.

Where to buy: 

Health food shops and some pet shops.

Cat grass

This isn’t one plant, but several kinds of grass and unlike the plants listed above, cat grass doesn’t induce a high in cats. Common grasses include:

• Orchardgrass or cock’s foot (Dactylitis glomerata)
• Common oat or cat oat (Avena sativa)
• Barley
• Wheatgrass

Grasses contain micronutrients that may be of benefit to cats. Due to their reduced ability to digest grasses, cats will often vomit it back up, and it is thought to have a possible medicinal purpose to help the cat get rid of hairballs or other non-digestible products.

How to give: 

Plant in a garden bed or pots. Cats eat cat grass fresh.

Where to buy: 

Most garden centres.

Other cat attractants:

The plants below contain known cat attractants, but I cannot recommend them for use as they contain additional chemicals which are toxic to cats.

• Buckbean (Menyanthes trifoliata) – Mitsugashiwalactone
• Northern groundcone (Boschniakia rossica) – Boschniakine and boschnialactone
• Wild kiwi (Actinidia macrosperma) – Dihydronepetalactone, iridomyrmecin, and dihydroactinidiolide
• Indian nettle roots (Acalypha indica) – Isodihydronepetalactone and isoiridomyrmecin
• Olives – The isoprenoids in olives is chemically similar to Nepetalactone in catnip)