Q:

What happens if cats drink coffee?

I was drinking my coffee the other day and I accidentally spilled some on the floor (a couple of drops).
My cat licked them. I don't really think this is a big deal because it was only two drops, but can anything happen to cats if they drink a (relatively) large amount of coffee?

A:

According to petpoisonhelpline.com, caffeine poisoning is "[g]enerally moderate to severe/life-threatening", but while "[...] cats appear to be more sensitive to the effects of caffeine than people", "1-2 laps of coffee, tea or soda will not contain enough caffeine to cause poisoning in most pets [...]".
So you should be safe with the current situation, but please do be careful!

A:

Caffeine is very bad for cats and dogs. Don't let your cats have any coffee, soda, tea, etc.
One tiny dose won't kill them, but you could be racking up organ damage each time. The HCCUA health website states that cats will get heart and nervous system damage from caffeine.  I imagine it would also hurt the liver, kidneys, and GI tract as well.
Plants make caffeine to kill off any creatures eating the plants.  Alkaloids (caffeine is an alkaloid) are intended to kill off anything that eats them, not just insects.  Humans and other plant-eating animals have developed defenses to common alkaloids, which is why people aren't really affected by caffeine.  Cats and dogs have no such defenses.

A:

Websearch says that LD50  (the overdose that will kill half the animals in the study) for caffeine is around 70 mg per 1 lb body weight (150 mg / kg body weight). As an example, instant coffee contains over 60 mg caffeine per teaspoon. So, the lethal dose of caffeine for a 15 lb (6.8 kg) dog would be 17 teaspoons of instant coffee. Stronger coffees such as Turkish coffee, percolated coffees, and energy drinks would take much less to become toxic for a dog. LD50 in a cat is 200 mg/kg ... So cats are less sensitive per body weight, but do typically weigh less.
The theobromine LD50 is about 1000 mg/kg in humans. But for cats it’s 200 mg/kg and for dogs it’s 300 mg/kg. So cats are more sensitive to tea and chocolate than dogs.
However, cats are much less likely to scarf down significant quantities of either than dogs are. They don't react to sweetness, among other reasons.
So you don't want to actively feed your cat these chemicals. But a few drops, or a few chocolate flakes, are unlikely to do any harm.

