Post-clipping alopecia, the condition where hair fails to regrow after shaving or trimming, is a common concern among cat owners. While this situation is well-known in dogs, it is less discussed regarding cats. To understand why hair may not grow back after trimming, it is crucial to understand the cat hair growth cycle.
Understanding the Hair Cycle
Hair follicles, which are pockets within the skin, are present in cats from birth. Hair consists of specialized skin cells that require stimulation to grow. The exact mechanisms behind this stimulation are not yet fully understood.
In a normal hair cycle, follicles form, grow to a predetermined length, and then sheds. The cycle repeats continuously. Hair length varies depending on genetics and the location of growth.
The hair growth cycle consists of four stages:
- Anagen: The growth stage
- Catagen: The end of active growth
- Telogen: The resting phase
- Exogen: The shedding stage
How long each stage of the hair growth cycle lasts is influenced by factors such as health, age, gender, location, and breed. Additionally, neighboring hair follicles may be in different stages of growth. Consequently, regrowth after trimming can be delayed depending on what phase the majority of hair was in.
Other Factors to Consider
Certain cat breeds such as Rexes already have unique hair structure making them the most vulnerable to halted hair regrowth. Several other underlying factors can impact hair regrowth, including general health, hormones, seasonal changes, nutrition, temperature, and daylight hours. Illness and stress can trigger a premature shift into the exogen phase of the hair cycle, while dry and brittle hair may indicate poor nutrition. Veterinary advice is advisable in such cases.
For a normal, healthy cat, regrowing a full coat can take anywhere from 3 to 18 months, depending on breed and hair length. Hair regrowth may stop after clipping because the skin follicles may be predominately in a catagen or telogen phase. In such instances, it may take cats 6 months to 2 years to regrow their hair fully.
Disrupting Nature’s Design
Cat hair is not the same as human hair. Humans have continuously growing guard hair that is 8x coarser in texture which emerges from a single follicle. Our average active growth phase is around 7 years. Cats comparatively possess a double coat comprised of finer guard hairs and a downy undercoat. Their average active growth cycle is 6 to 18 months, and a single cat hair follicle can produce 5-7 awl hairs and one guard hair.
Cat guard hair acts as protective weatherproofing, similar to shingles on a roof. Guard hair has a crisp texture due to a tight melanin structure and smooth cuticles. The downy awl hair is softer with rougher cuticles and provides insulation.
Repeatedly trimming the hair weakens the guard hair shaft as it attempts to continue growing. Frequent shaving can ultimately lead to the complete stall of guard hair growth. Without guard hairs to protect the body from the elements, the thickened downy awl hair becomes the dominant growth, leaving the cat with only its fuzzy undercoat. This undercoat attracts and absorbs more dirt, leading to matting issues. The end result is an unnatural and damaged hair environment.
While there can be valid reasons to consider hair trimming, it is essential to recognize the possible long-term effects of disrupting the natural hair cycle.
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