Toy breed puppies and small adult dogs are vulnerable to hypoglycaemia - dangerous drops in blood sugar - that can cause seizures and death but are largely preventable with appropriate feeding management.
Toy breed hypoglycaemia creates episodic but potentially life-threatening welfare crises that owners are often ill-prepared for. The tiny body size that makes these breeds appealing also makes them physiologically vulnerable in ways that require knowledge and active management. Breeders and sellers sometimes fail to adequately educate new owners about feeding frequency requirements, and the perceived robustness of a lively, active small puppy can mask the actual fragility of its metabolic reserves. Hypoglycaemic episodes are distressing for both animal and owner: an affected puppy progresses from normal to collapsed and seizing within minutes. The breeding selection that produces extreme small size in toy breeds effectively selects for a population that requires more intensive care as a consequence. Puppies sold too young (before 8-10 weeks) are at particular risk due to weaning stress.