Why half a tablet is critical for a 5kg dog
Human vitamin D supplements contain doses far exceeding what pets can tolerate. A 5kg dog eating half a tablet likely ingested multiple times the toxic threshold. Even if the tablet was left out overnight, the active compound remains potent. Dogs this small lack the metabolic capacity to process such concentrated doses safely, making immediate intervention vital before calcium levels spike.
Vomiting is the first red flag, but it doesn't mean the danger has passed. Hypercalcemia develops stealthily over 12-72 hours, hardening soft tissues and damaging kidneys. By the time increased thirst or weakness appears, organ injury may already be underway. Bring the supplement bottle to help the vet calculate the exact dose consumed—this guides their treatment protocol.
The delayed crisis after vomiting stops
Many owners mistakenly relax when vomiting subsides, but this lull is when vitamin D's worst effects unfold. The compound triggers calcium leaching from bones into the bloodstream, overwhelming the kidneys' filtration capacity. For a dog this size, even modest calcium elevation can cause irreversible kidney mineralization within days.
Emergency vets will administer fluids to flush calcium and possibly drugs to inhibit intestinal absorption. Blood tests at 24 and 48 hours post-ingestion are non-negotiable—they catch rising calcium before symptoms return. Without this, your dog could seem fine for two days before collapsing with acute kidney failure.
Why the supplement form matters here
Chewed tablets release faster than intact ones, accelerating toxin absorption. Overnight exposure might degrade some ingredients, but vitamin D's stable structure means toxicity persists. The gel-cap or coating type also affects dissolution speed—mention this detail to the vet, as it influences how quickly they must act to block further uptake.
Time is tissue in these cases. At this weight, every hour without treatment increases kidney calcification risk. IV calcium binders work best when given early, so don't wait for worse signs. Emergency care now prevents days of hospitalization later—or worse, chronic kidney disease from delayed treatment.
Home observation isn't an option
Unlike some toxins where monitoring suffices, vitamin D requires proactive medical intervention. DIY methods fail because the toxin alters blood chemistry silently. By the time your dog drinks more or seems lethargic, cellular damage is already widespread. Small breeds face higher stakes—their tiny kidneys falter under calcium loads that larger dogs might tolerate temporarily.
Pack the vomit photo if you have it, note the ingestion time, and head straight out. Treatment within six hours dramatically improves outcomes. Vets may hospitalize for 48 hours of aggressive fluid therapy and serial bloodwork—this isn't over when symptoms ease. Recovery hinges on catching secondary calcium surges before they scar the kidneys.
For a dose worked out against your pet's weight, use the Vitamin D (Cholecalciferol) Toxicity Calculator.