Why do some rats have red eyes? - briefly
The red eye appearance results from an absence of pigment in the iris, exposing underlying blood vessels; this condition is typical of albino rodents. It originates from a genetic mutation that disrupts melanin synthesis.
Why do some rats have red eyes? - in detail
Rats that display a reddish hue in the eyes typically lack melanin, the pigment that normally gives the iris its dark color. The absence of melanin reveals the underlying blood vessels, producing a pink‑to‑red appearance. This condition is most often caused by albinism, a genetic mutation that disables the enzyme tyrosinase, which is essential for melanin synthesis. Albinism is inherited as an autosomal recessive trait; both parents must carry the defective allele for offspring to exhibit the phenotype.
Other factors that can lead to red‑colored eyes include:
- Leucism – partial loss of pigment that may affect the eyes, though the body fur retains some coloration.
- Cataracts – clouding of the lens can give a reddish or amber tint, especially in older or diseased animals.
- Inflammatory or infectious diseases – conditions such as uveitis can cause blood vessel dilation, making the eye appear redder than normal.
Breeds such as the Fancy Rat “Himalayan” display a dark mask with lighter body fur, but their eyes remain dark because melanin production persists in the ocular region. In contrast, pure albino strains, including the “White” and “Rex” varieties, consistently show red eyes due to complete melanin deficiency.
Genetic testing can confirm the presence of the albino allele, while ophthalmic examination distinguishes between pigment loss and pathological causes. Proper care for red‑eyed rats includes shielding them from bright light, as the lack of pigment reduces ocular protection against ultraviolet radiation. Regular veterinary check‑ups help detect cataracts or infections early, ensuring the health of the animal despite its distinctive eye coloration.