How do rats shed fur? - briefly
Rats undergo periodic molting, during which the outer hair layer loosens and is shed through natural loss and grooming. The process is continuous, with new fur growing as old strands are discarded.
How do rats shed fur? - in detail
Rats replace their pelage through a regular molting cycle driven by hormonal signals and environmental cues. The cycle begins with the activation of hair follicles in the dermis, where stem cells proliferate and differentiate into matrix cells that produce new keratinized shafts. Concurrently, the older coat undergoes apoptosis at the follicular base, weakening the attachment of the hair shaft to the papilla. As the new shaft pushes upward, the weakened old hair is released from the skin surface, resulting in visible shedding.
Key physiological factors influencing the process include:
- Photoperiod – longer daylight periods stimulate increased melatonin suppression, accelerating follicular turnover.
- Temperature – elevated ambient temperature triggers the growth of lighter, thinner guard hairs to improve thermoregulation, while cooler conditions favor denser undercoat production.
- Nutritional status – adequate protein and essential fatty acids support keratin synthesis; deficiencies slow follicular activity and may cause patchy loss.
- Hormonal fluctuations – thyroid hormones and cortisol modulate the rate of cell division within the follicle matrix.
The observable stages of a rat’s coat renewal are:
- Pre‑shedding phase – follicles enlarge, and new hair shafts become visible beneath the existing coat.
- Detachment phase – basal cells of the old hair undergo programmed cell death, reducing anchorage.
- Exfoliation phase – the old hair is released, often appearing as loose clumps or individual strands.
- Regrowth phase – emerging hairs reach full length, completing the cycle within 4–6 weeks for most laboratory strains.
External factors such as stress, illness, or parasites can disrupt the normal pattern, leading to excessive loss or localized alopecia. Monitoring the condition of the fur, skin integrity, and the animal’s overall health provides early indication of underlying issues. Proper diet, stable lighting, and a controlled environment help maintain a predictable molting rhythm and prevent abnormal shedding.