How overnight drinking changes the danger
When a dog drinks intermittently over hours, their body can't trigger normal thirst-regulation mechanisms—they'll consume far more than during a single gulping session. Stagnant water's foul taste often causes repeated small sips rather than one big drink, which is paradoxically riskier for water intoxication development.
The wobbliness appearing now suggests gradual sodium dilution reached a critical threshold while you slept. Unlike acute poisoning cases where symptoms appear rapidly, this slow onset means neurological damage may already be underway before you noticed anything wrong.
Why wobbliness demands immediate imaging
Veterinarians often prioritize brain scans in these cases because the prolonged exposure window increases cerebral edema risks. MRI or CT can reveal whether swelling is localized or widespread—this determines whether to use mannitol or hypertonic saline first. Blood tests alone won't show the neurological impact.
Your description of "wobbly" suggests cerebellar involvement, which affects coordination differently than cerebral swelling would. The vet will test proprioception by turning paws upside down—delayed correction indicates more severe impairment than general weakness alone.
The risk of rebound swelling during treatment
Overnight intoxication cases often require longer hospitalization because fluid shifts continue for 12-24 hours post-treatment. As IV fluids correct blood sodium, water may suddenly move out of brain cells, causing rebound intracranial pressure. Vets monitor for this by checking pupil reflexes hourly—uneven dilation means swelling is worsening.
Some dogs develop paradoxical dehydration after treatment as the body overcorrects. Your vet might switch from IV to subcutaneous fluids once sodium stabilizes to prevent this rollercoaster effect. Don't be alarmed if urination increases dramatically—this is the body's way of restoring balance.
Long-term neurological considerations
Dogs recovering from prolonged water intoxication may exhibit odd behaviors for weeks—staring at walls, circling, or temporary appetite changes. These usually resolve but require patience. Your vet may recommend omega-3 supplements to support nerve repair and gentle leash walks to rebuild coordination.
Avoid strenuous activity for a month; the brain's osmoregulation remains fragile. Schedule follow-up bloodwork at 2 and 6 weeks to confirm kidney function hasn't been compromised. Some dogs develop lasting electrolyte imbalances requiring dietary adjustments—your vet will tailor recommendations based on follow-up tests.
The step-by-step response, from the first minute to the vet visit, is in our Water Intoxication (Hyponatraemia) emergency guide.