Structural damage matters
Cracked plastic, failed stitching, bent hardware or unreliable closures can make continued use unsuitable.
Fit can change
Growth, weight change or coat changes may make intact gear the wrong size.
Consumables wear out
Filters, liners, batteries and replaceable components may have their own schedules.
Keep manufacturer guidance
Some products identify specific inspection or replacement intervals.
General product-selection information only. A pet's health, anatomy, mobility, breathing and behaviour can change what equipment is appropriate. Follow product directions and ask a veterinarian or qualified animal-care professional when those issues matter.