Why a 10-pound cat is at extreme risk
Small body weight magnifies the danger—what might cause mild symptoms in a dog can be fatal to a cat. Your 10-pound indoor cat has no prior exposure to natural toxins, making their system especially vulnerable. Vomiting after pond water isn't a coincidence; it's the first wave of toxin assault.
The green scum indicates a concentrated bloom, where microcystin levels can be 1000x higher than in clear water. Even two teaspoons of this water contain enough toxin to overwhelm a cat's liver. Don't wait for more symptoms; their smaller blood volume means toxins circulate faster.
Indoor cats versus outdoor hazards
Unlike streetwise outdoor cats who avoid stagnant water, your indoor pet lacks this instinct. Their curiosity—combined with algae's sometimes sweet smell—makes them lap it up eagerly. The vomiting you're seeing is their body's desperate attempt to expel what it recognises as poison.
Watch for unusual behaviour like pressing their head against walls or circling. These indicate neurological damage from anatoxins, which mimic neurotransmitters. Keep lights dim and noise low during transport—overstimulation can trigger seizures in toxin-affected cats.
The critical first aid you can provide
While you prepare the carrier, wipe your cat's face and paws with a wet cloth to remove algae residue they might lick later. Use lukewarm water—cold shocks their system, hot opens pores and could increase absorption. Skip food or milk; fats accelerate toxin uptake.
If the clinic is more than 20 minutes away, call them for phone guidance. They may advise giving plain Pedialyte (1 tsp every 10 minutes) to support circulation if your cat becomes lethargic. Never attempt this if they're semi-conscious—it risks aspiration.
What the vet will do differently
Expect immediate blood work focusing on liver enzymes (ALT, AST) and kidney values (BUN, creatinine). For cats, vets often start SAMe supplements early to support liver regeneration. Your cat may receive mannitol IV to reduce brain swelling if neurological signs appear.
Prognosis depends on pre-treatment symptoms. Cats arriving with just vomiting have a 70% survival rate with aggressive care. Those showing tremors or difficulty standing face longer recovery with possible permanent nerve damage. Demand a follow-up bile acid test two weeks post-recovery.
The step-by-step response, from the first minute to the vet visit, is in our Blue-Green Algae / Cyanobacteria emergency guide.