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Sialodacryoadenitis virus is an RNA virus, genus coronavirus.
*Note: for additional information on recognizing various signs of pain or discomfort refer to: Signs of Pain In Rats.
SDA 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.
Once exposed to the SDA virus rats can begin to show symptoms as early as 5 days (porphyrin staining) with respiratory involvement and cervical swelling by 7-8 days. In a laboratory setting the virus remains active in a single rat 7-10 days and doesn’t have a carrier state. In a multiple rat colony this time frame must be altered as the disease spreads form one rat to the next. In a breeding colony the time frame must be altered to include litter transmission as well as multiple rat transmission.
The secondary infections will persist for a longer amount of time, depending on the bacteria or other viruses involved.
In some cases the rats that survive the SDA outbreak have eye and/or respiratory damage for life.
Not all rats infected with SDA 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.
This virus also affects the harderian and intraorbital lacrimal glands behind the eyes. 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 SDA so deadly. With SDA 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.
In a laboratory setting where the rats haven’t been exposed to mycoplasma or other pathogens, the mortality rate for SDA is low.
The standard test for Sendai is the ELISA (enzyme-linked immunosorbent assay) which can be performed at several labs.
IDEXX RADIL offers a newer test: MFI (Multiplex Fluorescent Immunoassay) which is more sensitive. Have your veterinarian contact the testing facility for instructions on collecting and sending the blood sample.
During a viral event broad-spectrum antibiotics are given to the exposed rats to treat the, often fatal, secondary opportunistic bacterial infections. Usually that approach works well. However, there are times when the bacteria involved is resistant. A culture and sensitivity test can ensure that the antibiotics given are appropriate
*Note: Before having blood drawn for an ELISA test you must allow time for antibodies to develop. This will take 2 to 3 weeks after the initial exposure (1-2 weeks after clinical symptoms appear). Testing a clinically ill rat can often result in false negative results.
Treatment for secondary bacterial infections that often accompany this particular viral infection, and seen most often in very young, and very old rats, or those rats that are immunosuppressed are as follows:
Broad-spectrum antibiotics such as those used for mycoplasma respiratory infection given at the maximum dosage for 3-4 weeks. Refer to the Rat Medication Guide for broad-spectrum antibiotics.
*Note: Treatment with antibiotics must be aggressive to be effective.
For eyes, use a topical ophthalmic antibiotic ointment.Lubricate with natural “tears” to help with dryness.
Keeping your colony healthy can give the rats an edge in the event of an outbreak. Good nutrition and cleanliness can help a rat’s immune system stay strong. Rats suffering from inadequate nutrition or that live in poorly maintained environment will have a significantly lower chance of surviving a major outbreak.
*Note:: Rat keepers who breed even one litter need to focus on the extended responsibilities of the breeder.
During this time any visitations to your quarantined rat(s) must be followed by waiting at least 3 hours before returning to your main colony. Sanitizing your hands, blowing your nose, and washing your clothes will minimize the risk of infection.
Being airborne, an in home quarantine is not effective for a virus.
A breeding colony that has a viral infection MUST be completely shut down. Once it has recovered the breeder must observe a full post infection-quarantine.
A full post-infection quarantine consists of absolutely no rats in or out (including no litters born). The length of the quarantine varies anywhere from 2- 4 months after the last signs of illness or the last babies are weaned and symptom free. It is highly important that NO new litters be bred during this time. Viral infections can literally be perpetuated forever if litters are continuously breed during & after an outbreak. When this happens you can have a situation where the SDA becomes enzootic.
The breeder has a responsibility to make others aware of the outbreak. In case of exposure and to keep the diseases contained immediately alert other rat keepers and breeders to the possibility of contamination in the area. To reduce the risk of an outbreak it is recommended that new clients NOT visit the rattery. A closed rattery is less likely to contract or transmit disease. All ratteries, even closed ratteries, should practice a quarantine time each year for several months (no new rats and NO breeding) to ensure a virus free population.
Due to the extremely high risk of viral infection groups or individuals that perform rat rescue services should NOT breed their rats unless the strictest of quarantine procedures are followed. It is also is a good practice to limit your rescuing to one species.
There you will also find a form for reporting your own viral outbreaks. By honestly entering information to this database people will become more aware of the dangers and it will provide the rat community with the necessary data to help in the prevention of viral outbreaks.
Posted on June 25, 2003, 09:24,
Last updated on September 8, 2012, 19:50