Living with domesticated animals often means encountering “pet strands,” the common term for the hair or fur found on these companions. These strands are a ubiquitous part of pet ownership. Understanding their nature provides insight into a normal biological process.
What Are Pet Strands?
Individual pet hair strands are primarily composed of keratin, a fibrous protein also found in human hair and nails, making up about 88% of hair’s composition. Each strand originates from a hair follicle embedded in the skin. The hair shaft, the visible part of the hair, consists of three main layers.
The outermost layer is the cuticle, a translucent protective layer made of flattened, overlapping cells. Beneath the cuticle lies the cortex, which provides the hair’s mechanical strength, bulk, and contains pigment granules that determine hair color. The innermost layer, the medulla, is an open, unstructured region that may not always be present.
The Science of Shedding
Pet hair undergoes a natural growth and renewal cycle, which explains why shedding occurs. This cycle involves four distinct phases:
Anagen phase: An active growth period where hair grows to its genetically determined length, lasting from one month to several years depending on the breed.
Catagen phase: A short transitional period where growth slows and stops as the follicle prepares to release the hair.
Telogen phase: A resting stage where the hair remains attached but is no longer growing, while new hair begins to grow beneath it.
Exogen phase: When the old hair is expelled from the follicle and falls out.
Seasonal changes, such as longer daylight hours in spring and shorter days in fall, significantly influence shedding, prompting animals to adapt their coats to temperature changes.
Understanding Pet Allergies
Pet allergies are not caused by the hair itself, but by proteins found in an animal’s skin cells, saliva, and urine, collectively known as dander. These microscopic dander particles are lightweight and can easily become airborne, adhering to surfaces like furniture and clothing.
While hair can collect and distribute dander, it is the dander’s proteins that trigger allergic reactions.
When a sensitive individual inhales or comes into contact with these airborne proteins, their immune system overreacts, mistakenly identifying these harmless substances as harmful invaders.
This immune response leads to the production of antibodies, such as immunoglobulin E (IgE), which then bind to mast cells. Upon subsequent exposure, this binding can cause mast cells to release chemicals like histamine, resulting in common allergy symptoms such as sneezing, runny nose, itchy eyes, or skin irritation.