| Proestrus | Often about 6–11 days, but duration varies between dogs. | The vulva may swell and bloody discharge commonly appears. Male dogs may show interest, while the female may not yet accept mating. | Absorbs or contains light-to-moderate discharge and helps reduce staining on floors, bedding, and furniture. | Change the nappy regularly and check the skin for dampness, rubbing, redness, or irritation. |
| Estrus | Often about 5–9 days, although it can be shorter or longer. | Discharge may become lighter or less bloody. The female may be receptive to males and can become pregnant. | Helps manage discharge during walks or indoors when appropriate. | A nappy does not prevent mating or pregnancy. Keep the dog separated from intact males and supervise outdoor activity. |
| Diestrus | Usually several weeks; hormonal changes continue whether or not pregnancy occurs. | Heat-related behaviors and discharge generally decline. Some dogs may show mammary development or nesting behavior. | May no longer be needed once discharge has stopped and the dog is comfortable without it. | Contact a veterinarian if discharge is foul-smelling, heavy, pus-like, or accompanied by lethargy, vomiting, fever, or increased thirst. |
| Anestrus | Commonly a resting period lasting several months before the next cycle. | No typical heat discharge or mating behavior is present. | Usually not required for heat management. | Cycle length varies by individual dog, age, breed, health, and reproductive status. |
| Nappy Construction | Used during the portion of the cycle when discharge occurs. | Most designs include a washable or disposable absorbent layer, leg openings, a tail opening, and adjustable fastening. | The absorbent layer captures discharge while the outer layer helps limit leakage when correctly fitted. | Choose a fit that is secure but not tight. The dog should be able to walk, sit, lie down, urinate, and defecate normally. |
| Daily Use | Use only when needed and remove it for regular hygiene breaks. | Warm, damp material held against the skin for too long can increase discomfort and may contribute to skin problems. | Provides temporary cleanliness support in the home or during controlled activities. | Inspect the nappy frequently, clean the dog as needed, dry the skin thoroughly, and follow the product’s washing or disposal instructions. |
| Outdoor Management | Applies throughout the heat cycle when the dog is outside. | Male dogs may detect a female in heat from a distance, and mating can occur quickly. | May help contain discharge but has no reliable reproductive barrier function. | Use a leash, avoid off-leash areas, and do not rely on a nappy as contraception or as a substitute for supervision. |