Genetic Anomalies in Rats (I)

Over-spotted, White-pawed Rats and Albino Rats

Looking back at history, we can only give Jack Black the credit of breeding albino rats (as per historical accounts). Black's Albino rats became even more popular after the famous children's book author, Beatrix Potter, cast a white rat in one of her books. To some extent, this fondness to Albino rats is probably the reason why kids even started to keep rat pets. Ironically, the common white rat which we see in most pet stores nowadays are not actually Albino rats, rather, they are members of a specific specie of rats which have white coverings. But to most of us, it would be hard to tell which one is an Albino and which is not.

White and Albino Rats

However, this confusion does not extend to the other species of rats; as what we might have noticed, common wild rats have brown or grey coverings. It should be noted that Albino rats are not naturally occurring, that is, Jack Black only altered the genes of the wild rats and generations after generation, he finally bred a true blood Albino. Thus, the parents of the first Albino rats are actually brownish and their eyes are black. Albino rats are highly characterized by the absence of any black pigmentation in their bodies, their eyes included. These rats have red eyes, almost translucent hair and pink paws.

Spotted Rats

Eventually, the Albinos are again bred back to their ancestors, the brown and grey rats. Generations of breeding led to the birth of spotter rats. These rodents either have grey or brown facial coverings with white bodies, or they can have spots all over their bodies. Some of them have developed excessive spotting, most especially in cases where the Albino gene perfectly matched that of the brown or grey rat gene added to it. There are even cases where the rats developed other colors which are entirely distinct from the color of their parents.

White-pawed Black Rats

Although some rat species are naturally black, it was historically verified that the first jet-black (pure, dark black) rats came from agouti parents. Because of their unique health prowess and color, many researchers and scientist have also used these rats in laboratory experiments along with the Albino and Spotted rats. Eventually, these rats have developed white paws (which they got from their Albino parent), which made the rats adorable even to kids. Because of their unique appearance, these rats became very popular pets especially to those who do not want to have the conventional white rat which have become very common.  Moreover, through selective gene mutation, scientists are able to produce other breeds of rats which are not gaining popularity to pet owners worldwide.

Domesticated Rats

After years of research and gene mutation, scientists started to establish and set the basic requirements of what a domesticated rat should look like. To date, the approved types of genetically mutated rats which can be kept as pets are the Albinos, the black-eyed white rats, the white-pawed black rats and the Agouti. These rats can be cross-bred by their owners if they want -- this actually produced rats that have very different appearances. One of the most popular ones are the Siamese rats which are also known as the pointed rats. These rats have white underside with pink paws and tail; their bodies are spotted and their heads are white. There are so many other rat breeds now, some have furry tails; some have developed hairy paws (which is very uncommon), while many of these rats actually do not have hair!

Well, of course, the fancier the color of the rat, the more expensive and valuable it becomes. This is probably the reason why cross-breeders never stopped experimenting.

You may also check "Genetic Anomalies in Rats (Part II)" ;-)