Omias and Meeko were two very special little critters whom I was fortunate enough to have shared my life with, if only ever so briefly. Both of these domestic rats were pets of my close companion Kira, who is a "special little critter" herself. Omias was given to Kira, by a dear friend, as a gift and Meeko was rescued from being displaced when yet other friends moved into a residence that would not allow them to keep the rats. Both were precious in their own ways. Omias was ever the independant one while Meeko was the gentler more loving of the two. I had a lot of happy moments thanks to these two. <3 and R.I.P. 4 eva' Gurlz!
Both rats passed away this year from complications caused from common but serious respitory problems that all domestic rats suffer from. The root of the domestic rat’s problem is a very tiny organism – smaller than a bacteria-but a bacteria none-the-less, but bigger than a virus. It is named Mycoplasma pulmonis. After watching both of these much loved little friends die from this desease I decided to do some research about domestic rats and this deadly virus that is present in all pet rats.
Let's begin with the history of the domestic or "pet" rat.
Your rat’s Latin name is Rattus norvegicus. He now comes in innumerable colors and styles but he was once a brown creature living wild in southern Asia (not Norway). He found plenty of food and shelter near people, and by 1340 had become a pest that moved to all habitable areas in sailing ships. He was quite an unwelcome visitor. He arrived in Europe about 1346, and soon, over 23 million people became ill, 20-40% of the population.
But it was not the rat’s fault, he was as sweet and gentle as any of God’s creatures; it was just a flea he was carrying and the poor sanitation of the times. By 1856, folks were experimenting with rats in France. Living this life of ease, in cages, the rat's genes changed, and he became quite mellow. Finally, a white litter was born in Switzerland, around 1906. Its descents were sent to Philadelphia PA. where the Wistar Scientific Institute used its bloodline to develop more new strains of rats than ever before or after. As I said, these rats didn’t join us alone. They brought along old “friends” when they jumped ship. Friends they had had since the dawn of time. Besides the plague, those friends included the Mycoplasma, some viruses and bacteria that are now making your rat sneeze.
Domestic rats have a relatively short life span.
Rats were designed to live 3-4 years. Some genetic strains live longer than others – certain ones no more than 1-1 1/2 years. As in people, female rats tend to live longer than male rats. It has also been discovered that limiting their protein and caloric intake as pups increases the length of their lives.
There are many different genetic types of domestic rats.
Some domestic rats are Out-bred. That is, bred to maintain the largest pool of genes possible. It takes about 5 generations and 100 pairs to establish an outbred strain. A few of the common outbred strains include the Sprague Dawley, Wistar and Long Evans rat, often called a hooded or piebald rat.
Other strains of domestic rats are Inbred. They result from 20 or more generations of brother to sister matings. These strains have the smallest possible gene pool and so are very, very alike in all respects. By the fortieth generation, they are 99.5% genetically alike. Scientists love them, because they are such predictable cookie cutter rats. The most frequently used inbred strains include the Fisher 344, the Lewis rat, the Brown Norway rat and the Wistar-Furth rat.
The respitory deseases suffered by domestic rats are caused by the Mycoplasmal bacteria that is present in all domestic rats from birth. It is often just called MRM for Murine Respiratory Mycoplasmosis. It lives in mice, guinea pigs, and rabbits as well as rats but doesn’t seem to be as big a problem in them. It can even exist in your nasal passages where it does no harm. It was lurking there from the day of your rat’s birth; clinically silent but causing a slowly progressive disease from the nose to the lungs. Although we think primarily about its effect on the lungs, it occasionally causes genital infections, sterility and arthritis as well. It is the most important and common disease of rats.
There are some signs and symptoms to look for.
What happens, and when it happens depends on a lot of interacting factors: some Mycoplasma are stronger (more virulent) than others. More importantly, the number of other bacteria and virus that hitched a ride in your rat is very important as to when or if this disease develops. The symptoms include sneezing, crusty and runny nose and watery eyes. Over time this can progresses to loss of appetite, hair coat, wheezing, difficulty breathing and unkempt hair coat. Later, bronchitis, pneumonia, and emphysema develop. I would sometimes visit my conventional (contaminated) colonies at Baltimore City Hospital in the middle of the night – the sound was like a host of hoarse crickets all chirping and sneezing together.
If you notice any of these signs or symptoms in your rat, contact your veterinarian immediately!
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