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SDA
What Is It? SDA is an acronym for Sialodacryoadenitis. This medical term basically translates as "a swelling of the tear ducts and salivary glands." SDA is a type of coronavirus (a category of viruses that use RNA rather than DNA to replicate themselves). It is related to the Mouse Hepatitis Virus and the Rat Coronavirus. SDA only naturally infects rats, however laboratories have been able to purposely infect mice. SDA is a highly contagious virus that usually does not cause death on its own. Secondary infections are very common and are the leading cause of death in an SDA outbreak. An infected rat will be contagious for a full seven to ten days. However, it may take an infected rat up to two months to fully recover from this illness. SDA does not have a latent carrier phase. This means that once the disease has run its course, it is completely gone.
What it Does to Your Rat In general, viruses all operate similarly. A virus will invade a host cell, take over the operation of the cell, and replicate itself using the host cell’s resources. When replication is complete, the now dead host cell bursts open releasing hundreds and sometime even thousands of newly made viruses. These new viruses will continue the cycle of invasion, replication, and destruction With SDA, the primary areas attacked by the virus are the tear ducts, the Harderian glands (the glands that actually produce the "tears"), the salivary glands, the cervical lymph nodes (located in the neck), the trachea (throat), and the bronchi (located in the lungs). What this amounts to is an extremely weakened immune system. Literally opening the "back door" to secondary infections, such as mycoplasma pulmonis, which are the actual causes of rat fatalities. While SDA does not cause death by itself, it can cause permanent damage or complete loss of the eye(s).
How the Infection Spreads SDA can be transmitted in two ways. First, it can be transmitted by respiratory aerosol. This means, when an infected rat sneezes, it is sending out airborne viruses that can then be inhaled by any nearby rat. Or, these viruses that are now floating around in the air can land on your skin, your hair, or your clothing. Secondly, this virus spreads by direct contact with infected rats or with items that they themselves have come into contact with. Items such as food dishes, food, water bottles, toys, wheels, bedding, cages, etc… Direct contact can also be with airborne viruses that have adhered to you. The SDA virus is viable for up to three hours without a host. This means, it can be floating around in the air or sitting on a food dish, etc… for up to three hours and still infect a healthy rat that just happens to wander by.
Symptoms to Watch For Symptoms of SDA infection can vary between individual rats, but the following is a list of common signs to watch for.
Symptoms of SDA may (and usually are) accompanied by the symptoms of secondary respiratory infections listed below.
It is important to always be aware of how your rats behave when they are healthy. This way, when they do start to show symptoms of illness, it will be easier for you to recognize.
Testing for Infection The most accurate test for SDA is a blood serum test for antibodies. Antibodies are created by the infected rat’s immune system. They are created for the purpose of finding and eradicating the current viral infection and to protect the rat from being infected by that particular strain of virus in the future. Blood serum is the fluid portion of blood. The actual blood cells are carried in the serum. It can take two to three weeks from exposure to the virus and subsequent infection of the rat for the antibodies to form. This means you need to wait one to two weeks after the first symptoms were noticed to have the test performed. A veterinarian must draw blood from the rat in question while it is under anesthesia. Then the blood serum must be extracted from the whole blood. After properly preparing the sample, the veterinarian will send it to a laboratory that performs the test and interprets the results. If the rat in question is already deceased, testing can be requested as part of the post mortem examination. In case your veterinarian is not familiar with which lab to send the sample to, one well known lab is Charles River Laboratories. Here is a link that might help your veterinarian:
Charles River Labs Serology Testing Services Recommended Treatment SDA cannot be eliminated through the use of medications. The infected rat’s immune system response is the only way that the virus will eventually be eliminated. Proper treatment should consist of an aggressive antibiotic program prescribed by your veterinarian. The antibiotics are needed to fight off the secondary infections that almost always show up with SDA. These secondary infections are usually the actual cause of death. Mycoplasma pulmonis is the most common, but not the only, secondary infection associated with SDA. General supportive care is also essential. Provide a clean, comfortable environment that is quiet, free of drafts, and has reduced or dim lighting. This can be accomplished by setting up a hospital tank. Using an aquarium with a heating pad set on low, underneath only part of the aquarium is ideal. Make sure your rat has ample space to move away from the heat source in order to prevent overheating or exacerbating dehydration. Make sure the ill rat has a supply of fresh water at all times. If it seems like your rat isn’t drinking as much as it usually does, try encouraging fluid intake by offering diluted grape or apple juice a few times a day in addition the regular fresh water source. Only use juices that are 100% juice, without any added sweeteners. Remember to remove the diluted juice after an hour in order to prevent spoilage, which can cause stomach upsets. Also provide added nutritional support. In addition to your rat’s regular diet, be sure to offer the rat’s favorite healthy treats in order to encourage appetite. Nutri-Cal is an excellent and often enjoyed nutrition-packed supplement. It is high in calories for rats that aren’t eating properly and contains essential vitamins and minerals in a molasses and malt based gel.
Preventing an Outbreak Prevention is always the best medicine; therefore, this section will be the most in depth of the entire article. Remember, SDA can be transmitted via respiratory aerosol – it’s considered airborne. Thus, when visiting pet stores that carry rats, you should wait at least two hours before returning home to your rats. This waiting period provides time for any virus particles, which may have adhered to your skin, your hair, or your clothing to expire. Also, never handle rats at a pet store. SDA is also transmitted by contact, so each time you handle a strange rat, you are risking the health of your own rats. Even if you don’t touch any of the pet store rats, it’s still a good idea to wash your hands thoroughly with an antibacterial soap or to disinfect them with a hand sanitizer such as Purell. If you are extremely concerned about bringing SDA home to your rats, change your clothes immediately upon arriving home. Put the "pet store" clothes directly into the wash with bleach or a bleach alternative. The suggestions above are good advice and should be followed. However, quarantine is the rat fancier’s most powerful tool of prevention. The usual standard for a quarantine period is two weeks for a healthy rat that is not showing any signs of illness, and two months for a rat that does have symptoms. Quarantine means no rats can come into the rattery and no rats can leave the rattery. New litters are considered new rats, so breeding must stop during quarantine. If you continue to breed, the virus will continue to have new host rats to infect. Do not purchase, adopt, or rescue any rats while under quarantine. Do not sell, adopt out, or place any rats while under quarantine. The two-week quarantine is for new rats that you are bringing into your rattery – rats that appear healthy and show no symptoms of disease. The two-week quarantine also applies to rats that you have taken to a rat show and are now returning home with. Don’t forget rats that have left your rattery for breeding purposes, this quarantine applies to them too. If you have a pregnant doe in quarantine and she gives birth before the full 14 days are over, the quarantine has been broken. You must keep her and her litter under quarantine until the young are weaned. Then you must start the 14-day quarantine over again. A note about the two-week quarantine; this particular quarantine should take place in a separate building from your established rattery because SDA can be airborne. If you don’t have an appropriate temperature controlled place and your friends or family are not willing to help you out, then the two week quarantine must apply to your entire rattery – no exceptions. The two-month quarantine applies when an SDA outbreak has occurred. This quarantine is for your entire rattery, not just the infected individuals. Again, no rats in or out and no new babies. The 60-day quarantine starts when all current babies (including litters that are expected but haven’t arrived yet) are weaned or when all symptoms of disease have ended, whichever is the later. If for any reason the quarantine is broken (examples – unexpected litter or rat showing symptoms on day 43), it must be started over from the beginning. With more and more occurrences of SDA infection, new information has come to light regarding the standard quarantine times and the "wait before returning home" time. It is now suggested that a three-hour wait replace the standard two-hour wait before returning home from a rat-carrying pet store. There is also evidence that the two week/two month quarantine standards are not truly adequate. A three-week/three month quarantine time may be more appropriate. The majority of rat fanciers continue to follow the two-hour/two week/two month time frame. What you choose to do with this new information is your decision. Always be honest about the outbreak of illness in your rattery. Don’t handle anybody else’s rats when yours are infected or under quarantine as a result of illness. If you have rat-owning friends that you regularly visit with, change your place of visitation to a non-rat establishment such as a restaurant or a movie theatre. Please be understanding and considerate of people who are experiencing and SDA rampage. The person will have enough grief dealing with sick and possibly dying rats without a rude rat fancier adding to this. There is no need to point fingers when it comes to SDA. This virus can infect anyone’s rattery, no matter how wonderful the care given to the rats living there.
Conclusion By keeping the information contained in this article in mind and by practicing strict prevention methods, rat owners have a fighting chance against the dreaded SDA outbreak.
Information Complied from the Following Sources
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