In October of 2020, my colony picked up SDAV from another breeders rats that were brought in. It was not intentional and the breeder did not know their rats had it. When you get the virus and if you breed through it, all the rats including the babies will have the virus- but they wont show symptoms. You can pass it on to others without even knowing.


I've documented the virus and have photos to show, so if anyone else thinks they may be experiencing SDAV, they can have a place of reference. has an excellent article on SDAV, which I will be referencing below. It is definitely worth reading!

"Sialodacryoadenitis virus (SDAV) is an RNA virus, genus coronavirus.

SDAV is a highly contagious virus that weakens the immune system. Alone it is not fatal, however it opens the door for secondary bacterial infections that can kill. 

SDAV is an RNA coronavirus. It is an airborne virus that is contracted via respiratory aerosol commonly spread by direct contact with affected rats. Contact with food, bedding, cages, or other accessories used by infected rats can spread the disease. Viral secretions carried on human skin, clothing, or in mucus membranes can also contribute to the spread of this illness.


Not all rats infected with SDAV show symptoms.


The SDA virus often presents as a characteristic inflammation of submaxillary and parotid salivary gland (which can result in the necrosis of the tissue).


This will sometimes give the appearance of a shortened or swollen neck. Cervical lymph nodes can also be affected.


 In a visual diagnosis you will often see bulging eyes, lacerations, porphyrin discharge, ocular lesions, bleeding, infection of the eyes or surrounding tissue, or squinting due to photosensitivity. The eyes can be lost due to self-mutilation from scratching or infection. Sight can be lost or compromised for life. In some case the eye infection will cause facial swelling.


Eye bulging may take several weeks to subside due to retro-orbital swelling.

In secondary infections of the respiratory tract, and some of the other systems, the organism most often responsible, but not always, is that of mycoplasma. It is this organism that is responsible for the majority of respiratory disease that naturally exists in most pet rats, and which in rats, makes contracting SDAV so deadly.


With SDAV respiratory involvement and with the secondary infections you will notice such symptoms as: sneezing, fluid in the lungs, porphyrin staining from eyes and nose, loss of appetite, lowered fluid intake, weight loss, lethargy, and general respiratory distress."

My Experience

My rats exhibited respiratory signs first. There was an unusual amount of sneezing, and EVERYONE was sneezing. Then we had porphyrin all around their noses, neck swelling and then finally, death. I lost roughly 2/3 of my adult animals. I also had 3 younger litters on the ground, ranging from 3-5 weeks old.

My youngest litter experienced eye ulcers. A few of my slightly older litters were squinty, but no ulcers present.

I tested through Charles River Lab and below are the results of my Serology testing. I also tested for Sendai (MFIA SEND) below, as both viruses can be similar. SDAV was positive and Sendai was negative.



Posted below are photos of what the virus did to my rats. I sadly did not get any photos of the neck swelling, as only 4 of my rats showed that symptom. The link to the below can show examples of the neck swelling.

Porphyrin and Respiratory Distress

The photos above are of BLU Clark. He passed away 24 hours after these photos were taken. You can see he is squinting his eyes, and his fur is puffed up- he is obviously not feeling well. The amount of porphyrin and labored breathing show respiratory destress. SDAV itself does not cause these symptoms, but the secondary infections will. Most pet rats have mycoplasma and this is what causes the respiratory symptoms. 

Eye Ulcers

Shown above is what my youngest litter suffered from- eye ulcers. Most of the eyes crusted up and had lacerations on their eyeballs. Both red and black eyed babies had symptoms and gender or coat type did not matter. These babies were red/black eyed Siamese with Harley, Satin, and normal coats.

Medicated eye drops returned nearly all the babies eyes back to normal after a weeks use. One baby (the baby in the first two photos) her eye only returned to about 60% normal and it will have lasting effects on her. She is able to see and blink the eye, but it did not go back to normal like the other babies.

Cervical Swelling

The rat above is BLU Annie. I happen to find this photo on my phone, so it is not the best quality or representation of the cervical swelling that presents in SDAV (Ignore the food in her mouth haha). If you look right below her chin, you can see swelling. It is noticeable and almost "bull frog" like. The swelling stayed for around a week. Annie has since made a full recovery. The swelling does not mean instant death in your rats. They can recover from it. I personally had rats that showed this symptom both recover and passed away.

Other Potential Symptoms

Another potential symptom has popped up. I've had this happen at my rattery and another rattery that has the virus. I'm sure this is not a symptom of SDAV but of the secondary infections that the rats can get because of the virus. Severe head tilts happened in two of my rats. One was so bad the rat was put to sleep. The second rat, while it looks bad in the video, is she able to actually move around pretty normally and eat, drink and even climb pretty well. Rat in the video is BLU Jacey.

Treatment and Testing

So, what should you do if you think your colony has SDAV?

First thing is first, if you have even the slightest thought that you may have contracted the virus, you need to start ALL of your rats on to an antibiotic. Starting them onto an antibiotic as soon as possible could mean the difference between life and death in your rats. 

Remember, the virus doesn't kill your rats, its the secondary infections, and the antibiotics will help fight that. I suggest both Baytril and Doxycycline for all rats. Dosages can be found on the ratguide or given to you by your vet. 

After getting your rats onto an antibiotic, then next thing is to get ready to test your animals. I suggest testing through Charles River. You will need to make an account with them and order supplies through them. You want a Charles River LTM account.

After your account is approved and you need to figure out if you want to test by a blood test (serology) or a PCR (fecal).  Either test will work. PCR will test for an active infection, and serology will test for the antibodies. I used a serology test because roughly 3 weeks had passed since I had introduced new rats into my home and symptoms started to pop up. So I tested for antibodies. I also had all the supplies ready for serology testing so I did not have to wait for the PCR supplies to be sent to me and I was able to get a result much faster.

Quarantine Protocols for Breeders

This section is still under construction, but I will be adding what I have found out so far.

When a breeder gets SDAV, the first thing they need to do is quarantine. Which means no rats in OR our of your home. Any litters on the ground cannot be adopted out.

The next thing to do is make sure all your animals are infected with the virus. What do I mean by this? I mean that if you happen to have rats in different parts of your home, you will want to take bedding from the rats showing symptoms and mix it in with all your other rats. Your rats are going to get the virus no matter what and exposing them all at once means a shorter quarantine period and a shorter time of you having to battle the virus.

The next step is to decide on if you want to cull your "non essential" rats. Charles River usually recommends completely culling your whole colony and starting over with new animals, but this isnt feasible for breeders. Since I had three litters on the ground at the time that I got SDAV, I chose to cull the babies that I did not need. Which, while a tough pill to sallow, may be your best bet to saving your other rats. Less animals means less rats to catch the virus, less rats to suffer from the virus, and less rats for you to treat, and a quicker time frame for your animals to get healthy. This step is not needed if you have a very small number of animals, but for me and the health of all my rats, it was the right thing to do.

I would look up Charles River's guide on SDAV, and research a lot before making a decision like the one I made above. Culling may not be needed for you.

Alright, you've made what you consider to be all the right decisions for you and your animals. You have ordered supplies and have received your test results back with a positive marker on SDAV. You are in quarantine and are making sure that you do not come into contact with anyone or any place that may have rats (SDAV can live on your clothes for roughly 3 hours, and then can live on other fomites- which means you can give it to other people and then they can give it to their rats)!

You've also stopped any breeding's and pairings that you may have had going on. Breeding during this time is a huge 'NO' because any litters born during this time will also get the virus, and you'll continually have the active virus in your colony. If you continue to breed through the virus, and you sell your rats or place them in new homes, the rats at the new locations will get the virus and will get sick as well. 

How long do you need to quarantine for?

The "right length" of time to quarantine for is still being determined, but this is what I've found out so far.

After all the symptoms have subsided and your rats are "healthy" again, it's time to keep track of time. Charles River recommends waiting 2-3 weeks after all symptoms are gone to test your rats with a PCR test. a PCR test will tell you if the virus is still active in your colony. Now, you need to test EACH AND EVERYONE of your rats because while one rat can come up negative in the test, the one next to it can still be positive.

Remember, the virus moves from one rat to the next, so while one rat may be further into the timeline with the virus and no longer have the active virus, the rat next to it might not be quite there yet. This is why it's important to infect all your rats at the same time if you think you may have the virus.


The e-mail above is from Charles River and myself. As you can see we are still chatting and coming up with the best course of action.

As I get more precise information, I will edit this section. For now I do find the current information helpful.

What if you cannot test your rats?

Some of you may not have the access or funds to test your animals, and that is okay! The RatGuide has the best information for those that cannot test. 


"In a breeding colony the 6–8 week quarantine, begins after any weaned babies have ceased to be symptomatic, should be sufficient as long as no litters are born. Generally 8 weeks is considered the minimal post infection breeding colony quarantine."

Quarantining for at least two months is recommended for a breeding colony AFTER all babies are weaned AND there are no more symptoms. So when you see that your rats are now "healthy" after the virus, this is when your quarantine will begin.

After Quarantine

After quarantine, you are ready to get your rattery going again! Hopefully you've figured out how to test your rats through Charles River (or your vet can also test through IDEXX, you will need to ask them about it) or you've followed proper protocol and have waited the necessary amount of time needed to make sure your animals no longer have the active virus and are healthy! 

The question is, can you get back to breeding?


While the rats who have gone through the virus event may have some symptoms for the rest of their life (respiratory issues are the most common) you can still breed your animals! The offspring of them will be healthy and happy! (I do not recommend breeding any animals that the virus hit very hard and may still have side effects from the virus.)

Hopefully, you and your animals made it out to the other side a-okay. This virus has been known to devastate breeding colonies, but if your vigilant and work fast, you have the best chance of saving most of your rats.


Images are of the babies from the Eye Ulcers section. As you can see most of them 100% recovered!