How potassium hydroxide differs from ordinary battery risks
That brown liquid leaking from the AA battery isn't just 'dirty' — it's potassium hydroxide (KOH), a strong alkali used in industrial drain cleaners. Unlike intact batteries that harm via electricity, this chemical burns on contact, explaining your cat's immediate drooling. Their 5 kg size means even small amounts coat more of their mouth surface.
KOH dissolves proteins and fats in tissues, creating soap-like lesions that penetrate deeper over time. Rinsing seems logical but spreads the chemical — water reacts with KOH to release heat, potentially worsening burns. The drool strands mean his tongue and gums are already damaged.
Why cats suffer more from mouth burns
Your cat's grooming instinct puts them at special risk — after chewing the battery, they likely licked their paws, transferring KOH to their tongue and throat. Cats also have thinner oral tissues than dogs, so burns reach sensitive layers faster. The 5 kg body weight means systemic absorption of potassium could disrupt heart rhythms sooner than in larger animals.
Watch for pawing at the mouth or reluctance to move the jaw — these suggest pain escalating as the alkali continues destroying tissue. Even if drooling lessens, that might mean throat swelling is blocking saliva rather than improvement.
The hidden danger of delayed symptoms
Unlike electrical burns from intact batteries, alkali damage keeps progressing hours after exposure. What looks like mild redness now could ulcerate by tomorrow as the chemical reacts with tissue oils. Your cat's small size makes dehydration from pain-induced anorexia especially dangerous.
Vets often see the worst damage 12-24 hours post-exposure when tissues slough away. Don't wait for visible mouth sores or lethargy — those signal advanced injury. Emergency flushing with special solutions can neutralize residual alkali before it penetrates deeper.
Long-term complications unique to chemical burns
Surviving the initial crisis doesn't guarantee safety — alkali burns trigger abnormal scarring as they heal. Your cat might develop strictures that narrow the esophagus, making swallowing difficult weeks later. Small bodies like his 5 kg frame show these complications sooner than larger cats.
Watch for gagging when eating or unexplained weight loss during recovery. Your vet may recommend periodic esophageal stretching or liquid diets if scar tissue forms — another reason leaking batteries need immediate professional care.
The step-by-step response, from the first minute to the vet visit, is in our Batteries (Alkaline, Lithium, Button) emergency guide.