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 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 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.
· Swelling located in the head and/or neck area
· Eye (s) bulging from the head
· Ulcers of the cornea (in the eye)
· Bleeding inside of the eye
· Photosensitivity (avoiding bright lights)
· Excessive squinting and/or blinking
· Excessive rubbing of the eye(s) (may lead to self-mutilation)
· Porphyrin (a reddish secretion that is not blood) staining
of the eye and/or nose area
· Porphyrin discharge from the eyes or nose
Symptoms of SDA may (and usually are) accompanied by the symptoms of
secondary respiratory infections listed below.
· Labored breathing
· Congestion
· Noisy breathing (gurgling or raspy sound)
· Excessive sneezing (not just the occasional sneeze)
· Nasal or ocular (eye) discharge
· Porphyrin staining of the eye and/or nose area
· Rapid weight loss
· Reduced or non-existent appetite
· Lethargy
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 the ELISA test. ELISA is an acronym
for Enzyme-Linked Immunosorbent Assay. The ELISA test measures antibodies
in blood serum. 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 ELISA 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 and interprets the results of the ELISA
test. If the rat in question is already deceased, testing can be requested
as part of the post mortem examination.
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 to 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 three weeks for a healthy rat that is not
showing any signs of illness, and three 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 three-week quarantine
is for new rats that you are bringing into your rattery – rats
that appear healthy and show no symptoms of disease. The three-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 21 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 21-day quarantine over again. A note about the
three-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 three week quarantine must apply to your entire rattery –
no exceptions. The three-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
90-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 later). If for any
reason the quarantine is broken (examples – unexpected litter
or rat showing symptoms on day 73), 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. 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 nonrat establishment such as a restaurant or a movie
theatre. Please be understanding and considerate of people who are experiencing
a 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.
