The most important aspect of these viral diseases in rats for all to remember:

The viral diseases by themselves are not that deadly or terribly dangerous to rats. The problem lies in the fact that pet rats often carry a multitude of diseases.

When Sendai and Sialodacryoadenitis (SDA) are combined with other diseases, such as Mycoplasma pulmonis, as well as CAR, KRV to name a few; pet rats become much more ill than they normally would have. These viral diseases exacerbate the progress of Mycoplasmosis, causing it to be much more serious than it normally would be without the presence of the virus. The reason epidemics and death follow rat and mouse shows is that in the pet rat, it's extremely difficult to find one that isn't infected with Mycoplasma pulmonis.

Some people would rather waste their time bashing others than bother with accepting the facts. They look for any excuse to perpetuate the myths that rat shows are safe, they perpetuate the myths that viral diseases are no big deal. In a laboratory setting SV and SDA may not be a major problem but for the pet rat, bringing a carrier to a show can and does cause the death of hundreds of pet rats. Anecdotes and observations made by those with zero understanding of how diseases are spread are not facts.

Healthy, robust rats living in a stress-free environment rarely show clinical signs of infection with Sendai virus or SDA. Once infected, however, they become carriers of these diseases. That means that, while they themselves are healthy, their acquired immunity to these diseases will keep them from becoming ill when they are once again infected. However, as carriers, they are capable of passing these viruses along to their offspring, as well as to other rats they come into contact with. Since these viruses are spread through the air, if carriers and those with active infections are not strictly isolated from those who have never been infected or those who are not healthy or are highly stressed, the disease will spread to these other populations. That means that any rat taken to a show can be infected. It also means, because of the current lack of understanding of the way these viruses affect those infected with them and how they spread to uninfected members of the population, those rats purchased from shows have a high risk of being actively infected or are carriers. When such rats are placed directly into the home population, the established previously healthy colonies are at risk for active infection, and those that survive then themselves become carriers. The lack of understanding of how these viruses infect and spread from one animal to another is what is causing the epidemics of SV and SDA that have been occurring after shows around the country.

There are no "sides" when it comes to the spread of SV and SDA. There are only facts. Unfortunately, many of those who stand to lose their reputation and income by acknowledging the facts of these viruses tend to be the ones who are most vociferous in dismissing them. Because these "experts" have no facts to support their claims that SV and SDA are not important (i.e., not highly contagious and lethal), they are left trying to stake their position by doing the only other thing available to them: attacking those who are working to educate pet rat and mouse pet keepers and breeders. As a registered veterinary technician, rat keeper, occasional breeder, and educator, all I care about is healthy rats. I don't care about colors, I don't care about varieties, and I don't care about what a rat looks like and I don't care about winning a prize.

I don't care to call myself an "expert" since that seems to imply that I know everything that there is to know - and being a RVT, I know that we keep expanding our knowledge about the animals we work with and keep as pets. So, what do I care about? I care about keeping pet rats living the longest and healthiest lives possible. While observation plays a role in how I care and instruct others to care for their pets, the facts resulting from published research play a significant role and underlay the foundations of proper care.

I posed a couple of questions to a board-certified laboratory animal DVM, Diplomat ACLAM, with twenty years of experience whose research has involved viral diseases of rats. Because of flack received by busy researchers who do not have the time to argue by email with the breeders who want to mislead the public, I am not allowed to give the name.
I can say however that by web surfing, searching through laboratory animal research sites, I spent approximately five minutes looking for DVMs who could answer these questions.

It's still a major problem in the pet rat world because pet breeders do not normally have the facilities to quarantine properly in order to actually clear the disease.

In research colonies, where we have many genetically modified rats and mice, we often have animals with deficient immune systems and these animals may have lifetime infections, with continued shedding of these viruses. This scenario is much less likely in pet rats.

Less likely in pet rats because we do not infect our rats with diseases on purpose, we don't genetically modify them so that we can study the disease.

Do you have a separate building to quarantine rats in? The viral diseases travel through air ducts in your home. Do you have bio-suits with masks to wear so that you can put them on when caring for the infected rats and can take them off before you handle the uninfected? If you don't then you are not quarantining properly so that these viral diseases will clear out of your colony.

Your own colony may not exhibit any signs of disease, yours may live out their life span even while they are subclinically infected. These rats could still cause other rats who have never been exposed to become ill.

Rat shows may worsen the problem because viruses evolve over time and location, yielding multiple strains that circulate at the same time within different populations. Bringing together rats from various enzootically infected colonies in a single location is giving the virus strains lots of opportunity to enter uninfected populations, causing havoc. In the laboratory animal world this would never be permitted to happen.....

There are no vaccines for rats, you risk the lives of your rats each and every time you take them to a show. When you breed them, you may be shortening their lives by breeding those who are infected with a myriad of diseases. Ask yourself, is it really worth it?

Rat shows are fun, people don't want to give up their fun and that's understandable. The fact is the lives of our pets are more important than our social activities and our fun. Instead of bashing me by trying to twist the facts, maybe people should put the needs of their pets above their wants. If you are a responsible pet owner you'll do that.

 For those of you who would like to do some research of your own here are some sources that I used: