Albino Rat?

Question

They're being noisy little guys tonight! lol! I'm a first time rat owner btw.

Ok, I got my two boys about 4 weeks ago.

One is albino, like a siamese, and I've noticed his eyes are half closed a lot of the time. I don't just mean when they're sleepy!

I understand albino's can have poor eyesight, but it's not overly bright/dark in the room.

Was just wondering if it's normal to have his eyes half closed like that, he looks pretty stoned!

His appetite and behaviour are normal. Just looks like Harry from 3rd Rock, if anyone else remembers it!!

Thanks!

Answer 1

He'll be OK I've got two siamese very pink pale eyed, and they do the same, also they are the only two that head sway all my other ratties have black/brown eyes and they don't sway, its always a problem with albino's, avoid strong sunlight is main thing,  they get along and manage just fine, you could make sure he has a dark bed to go into in the daytime, sometimes I notice these two startle a bit more than my others,

Answer 2

Albinos have a number of differences in their visual systems compared to normally pigmented animals. In a nutshell, albinos have no pigment -- no melanin -- in their eyes. This means no pigment in the iris. That's why the iris looks red -- the only color left comes from blood in the capillaries. Albinos also lack pigment deeper in the eye, pigment which normally absorbs light. Without it, light inside the eye scatters. The consequence is that the albino's eye is flooded with light. Over time, the light causes retinal degeneration. In addition to all this, albinos have abnormal neural connections between the eyes and the brain. The end result of all this is that albino rats have very poor vision. Here are the specifics:

Low visual acuity: The albino rat's inability to control levels of incoming light, the scattering of light inside the eye, and gradual retinal degeneration lead to very poor visual acuity. Albino rats have poorer visual acuity than pigmented rats (Prusky et al. 2002), estimated at about 20/1200 vision.

Impaired vision in bright light: dazzling: Albino rats can't control levels incoming light. Normally-pigmented animals have a pigmented iris that surrounds the pupil and controls how much light shines onto the retina. Albinos lack pigment in their irises, so light passes through the iris, dazzling the retina. In bright light, albinos may not see anything at all because their retinas are overwhelmed by the incoming light.

Impaired vision in low light:

• Few rods, few photoreceptors: Rods require a melanin precursor to develop (dopa). Albinos can't make this. Without it, about 30% of the rat's rods fail to develop (Ilia et al. 2000). Not only does the albino rat have fewer rods, but even early in life the rods it does posess have fewer rod photoreceptors (called rhodopsin) than the rods of pigmented rats (Grant et al. 2001). Rods and their photoreceptors are useful for detecting low levels of light, so albino rats may have trouble seeing in low light conditions.

• Delayed dark adaptation: Albino rats take longer to adapt to the dark than pigmented rats. Specifically, pigmented rats adapt to the dark within 30 minutes, but albino rats take about three hours (Behn et al. 2003). This delay comes from the albino rats' lack of melanin in their eyes. Eyes that lack melanin have reduced bio-availability of calcium (Drager 1985). Calcium plays a key role in a retina's ability to adapt to the low light conditions (called dark adaptation) (Fain et al. 2001).

• Night-blindness in albino rats: conflicting reports: Once dark adaptation is achieved, Balkema (1988) reports that pigmented rats have a much lower dark-adaptation threshold than albinos. In other words, Balkema reports that pigmented rats can see under conditions of much lower light than albino rats. However, Green et al. (1991), Herreros et al. (1992), and Munoz et al. (1994) found no such differences in dark-adaptation thresholds between albino and pigmented rats, indicating no albino night blindness.

Problems coordinating what the two eyes see: There are even further visual differences between albinos and normally pigmented animals, involving the eye-to-brain connection. In normal mammals, the left side of each eye is connected to the right hemisphere of the brain, and the right side of each eye is connected to the left hemisphere. Albinos have a much simpler connection: most of the left eye is connected to the right hemisphere, while most of the right eye is connected to the left hemisphere (Silver and Sapiro 1981). In addition, the deeper neural projections involved in vision are disorganized (Creel et al. 1990). The consequence is that albinos may have trouble coordinating and processing what their two eyes see.

Poor depth perception: The albino rat's poor visual acuity leads to poor visual depth perception. In the visual cliff experiment by Schiffmann et al. (1970) described in the previous section, rats were placed above a sheet of glass over a ledge and dropoff. Pigmented and albino rats with intact whiskers relied on their whiskers instead of their eyes and chose to walk on the glass over the dropoff as often as the glass over the ledge. When the whiskers were clipped, however, the rats were forced to rely on visual cues. Pigmented rats with clipped whiskers chose the glass over the ledge. Most whiskerless albino rats also chose the glass over the ledge, but a large percentage of them (20%-33%) made no choice at all but stood stock still. This failure to choose indicates that albino rats do not use visual information to perceive depth as readily as pigmented rats do. Albinos appear to be more impaired by whisker removal than pigmented rats, probably because their fallback sensory system -- vision -- is so poor.

Pet owners often note that albino rats bob their heads and sway frequently. This bobbing and swaying may be the albino's attempt to increase its perception of depth using its greatly impaired vision.

Poor motion perception: Albino rats have greatly impaired motion perception. They are not motion blind, but they have poor motion perception when compared to pigmented rats. Albino rats require about twice to three times the coherence level to distinguish coherent motion patterns from dynamic noise.

Specifically, Hupfeld and Hoffman (2006) presented rats with moving dot patterns in which dots moved randomly on a screen. A coherent moving pattern was created by a proportion of the dots moving to the right. The percentage of dots moving to the right was called the "percentage of coherence." So, a 100% coherence meant all dots moved to the right; 70% coherence meant 70% the dots moved to the right while 30% moved randomly, and so forth. Both pigmented and albino rats could distinguish between a random pattern and a 100% coherence pattern. When the coherence was reduced, discrimination performance declined in both pigmented and albino rats. Pigmented rats tended to do better, but not significanly so, down to 30% coherence. Below that coherence level pigmented rats did significantly better than albinos. In sum, pigmented rats could discriminate a pattern of 12% coherence from dynamic noise, while albino rats needed about 30% coherence to make the distinction.

Retinal degeneration: In addition to dazzling them, ambient light (even at low intensities) can cause irreversible retinal degeneration (green light; Noell1966). Rods, because they are so sensitive to light, degenerate more easily than cones (Cicerone 1976, Lanum 1978), which reduces the rat's ability to see in low light. Twenty four hours of ambient light is enough to cause some degeneration, and a few weeks is enough to completely degenerate the outer retina (Lanum, 1978), by causing loss of photoreceptors and cell bodies (Wasowicz et al. 2002).

Retinas more easily damaged: When the rat's eyes are subjected to pressure, the albino rat's retina sustains more damage than the pigmented rat's retina (Safa and Osborne 2000).

Lens fiber anomalies: Albino rats also have abnormal lens fibers compared to pigmented rats. When the lens fibers of pigmented and albino rats are observed under the electron microscope, pigmented rat lens fibers have many "ball and socket" joints between them, but albino rats have few of these joints. The membranes of albino rat lens fibres are often ruptured (Yamada et al. 2002).

A note about foveas: Many normally pigmented mammals like humans and other primates have an area of the retina that is packed with cones, called the fovea. The fovea is surrounded by an area with many more rods than cones. The fovea therefore has very sharp, color-sensitive vision that is useful in bright light, while the area surrounding the fovea has blurry, mostly monochromatic vision that is useful in low light conditions. Albinos of these species don't develop a fovea, so they are missing this patch of sharper color vision. However, in rats, even normally-pigmented rats don't develop a fovea (Reese 2002), so fovea hypoplasia in albinos isn't an issue in rat vision.

What if albinos are provided with a missing enzyme during developement? Albinos have a mutated tyrosinase enzyme. This enzyme is essential for the complex chemical reaction leading to melanin. This chemical reaction passes through I-tyrosine, L-DOPA, and I-dopaquinone on its way to melanin. L-DOPA itself plays an important role in retinal development. Lavado et al. (2006) examined transgenic albino mice that had the gene for tyrosine hydroxylase spliced in to their genome. Tyrosine hydroxylase is an enzyme that will do part of what the missing tyrosinase does: it will oxidize I-tyrosine to L-DOPA, but it won't go any further toward melanin. The resulting animals were phenotypically albino, but they did not have many of the visual problems of albinos: they had normal photoreceptors, normal neural pathways in the brain, and improved visual funchtion.

however him eating and being normal may just be how he is maybe a birth trama or something from before you had him .. if he start looosing his appitite and not being like him get him checked out

Answer 3

It is pretty normal for an albino rat to have its eyes half closed. Although the light in an area may seem normal to us, an albino has less visual protection and therefore, regular light is dazzling to it and the rat may have to squint a bit.