Sialodacryoadenitis Virus (SDAV)
Sialodacryoadenitis (SDA Virus)
is a natural occurring pathogen in rats. It is a corona virus antigenic ally
related to the mouse hepatitis virus (MHV), rat corona virus (RCV), and the
human corona virus OC38. Clinical disease caused by this agent alone is
self-limiting and is highly infectious, You cannot treat for this
disease, but immediate treatment for any secondary bacterial infection is the
only hope for some affected animals.
SDA virus is transmitted very
quickly through the air, or by direct contact, when a rat comes in contact with
other rats. Rats may not always show symptoms of SDA virus while they are
transmitting the disease to other rats. This is what makes it so dangerous to
expose your rats to other people’s rats. Even a separate room is simply
not adequate enough for quarantining when disease is spread through the air. A
separate home is far better. Infected animals carry and secrete the virus for
about a week. The disease can occur frequently in a particular population, but
the organism does not exist in a latent, carrier state.
Sneezing, eye and nose discharge,
swelling under the neck, caused by cervical edema, enlarged cervical lymph
nodes, and necrotic inflamed salivary glands, squinting, blinking, and eye
rubbing, swelling or infection of the eyes or surrounding eye tissues, ulcers of
the cornea, bleeding into the chamber of the eye that lies in front of the lens
can be symptoms of SDA virus and may be seen for several weeks in your colony,
but each individual rat will only show them for a week. You could see many other
symptoms in an outbreak which are caused by secondary infections.
Self-mutilation may occur as a
result of scratching affected eyes, and damage can be permanent. Some young rats
may even remove the eyeball altogether. Most other eye lesions usually resolve,
but occasionally may progress to chronic inflammation of the cornea, and
abnormal enlargement of the eyeball itself. During the infection rats usually
remain active and eating, although acutely infected rats will lose their
appetite and can start dehydrating.
A rats immune system becomes week
and secondary infections can set in fast. It is important to start treatment
right away. Pregnant and nursing rats should not be treated as antibiotics could
cause problems with the babies. If a pregnant or nursing female is affected and
pneumonia follows, treatment will likely be necessary to save her life. It
recommended that you move babies, pregnant and nursing moms away from the rest
of your rats. It's important you must stop breeding for at least two months from
the birth date of your last litter, or from the end of all symptoms, which ever
is longer.
Do not bring any new rats into your
home during this period. New rats will just keep it going. Mycoplasma pulmonis,
is also the most common secondary infection to accompany SDA virus, but CAR
bacillus is also common. You will need to start treatment immediately, so treat
as if you are treating mycoplasma related pneumonia.
The only way to ensure that your
rats do not become infected with SDA is to keep them isolated from all other
rats. Any newly acquired rat must be considered suspect until it has gone
through the quarantine period without incident. Simply keep your rats isolated
from other rats if possible.
Adapted from the RMCA Gazette.
Credits and special thanks to Mary Ann Isaksen for her guidance and endless
support. Without her kind heart, many more little rats would have been lost to
this dreadful disease.
SDA testing done
at the University of Guelph, Canada
Duration of protection from reinfection following exposure to
sialodacryoadenitis virus in Wistar rats.
Percy DH, Bond SJ, Paturzo FX, Bhatt PN
Ontario Veterinary College, University of Guelph.
Wistar rats were inoculated intranasally with approximately 10(3)
median mouse lethal infective doses of sialodacryoadenitis (SDA)
virus. Animals were subsequently selected at random, removed to a
separate isolation room, and reinfected with SDA virus at 3, 6, 9,
12 or 15 months. Pre- and post inoculation serum samples were
collected from all animals during the course of the study and
evaluated for antibody titers to SDA virus. All experimental,
control and sentinel animals, following inoculation with SDA virus,
were necropsied and examined for lesions consistent with SDA.
Salivary gland lesions were minimal to absent in rats reinfected
with SDA virus for up to 12 to 15 months after the initial exposure
and minimal to moderate in the respiratory tract at 12 or 15 months.
SDA associated lesions were extensive in age matched control animals
examined at each time period of reinfection with SDA virus. Thus,
prior exposure to SDA virus did protect against the development of
typical salivary gland lesions for up to 15 months. Recovered
animals were evaluated for their ability to transmit the virus
following reinfection. Rats reinfected at 6 or 9 months were
infectious to their naive cage mates.
NOTE: The
results indicate that
reinfection with homologous rat corona virus can occur as early as 6
months after the initial infection, and such rats can transmit the
infection to contact controls.
Sendai Virus
Vaccine
Vaccine
protective effect of inactivated virus vaccine on Sendai
virus infection in rats.Tsukui M, Ito H, Tada M, Nakata M, Miyajima H, Fujiwara K
Rats which had received two doses of inactivated Sendai virus
vaccine were resistant to intranasal virus challenge. Vaccination
was equally effective when administered by intravenous,
intraperitoneal, intramuscular, or subcutaneous routes but not the
intranasal route. Rats vaccinated intraperitoneally with inactivated
Sendai virus vaccine were protected from contact infection. Suckling
rats born to vaccinated dams were resistant to challenge infection
at 3 weeks of age, but the resistance was not demonstrated after
weaning at 4 weeks of age.
Rat Virus or
RV, is the official taxonomic name of a parvovirus often called KRV or Kilham
rat virus in America. It was discovered by researchers Kilham and Oliver in
1959. Many rats normally carry this virus subclinically with no significant
signs or symptoms; they are the natural host for this virus. As with most rat
diseases it can be worsened by the presence of other diseases, or conditions
that suppress the immune system.
Obvious illness in rats caused by this parvovirus is extremely rare in the
laboratory rat but may not be quite as rare in the pet rat. This disease affects
multiple organs in the body but generally affects only the unborn and young,
growing babies. If the older rat were immunosuppressed clinical signs could
possibly occur.
Symptoms:
Symptoms range from none to spontaneous death. Known symptoms are: abdominal
swelling, dehydration, scrotal cyanosis (turning blue), resorption of litters in
pregnant rats, stunted growth of young, and jaundice in babies. Ataxia may also
be seen; this means they are unable to stand properly and may have a drunken
appearance for no apparent reason.
Transmission:
This virus is passed through direct contact with an
infected rat, which gives us another reason to keep pet rats isolated from wild
rats. If mother rat is an infected carrier she can pass this onto her babies
through milk. The virus can also be transmitted via fomites, i.e. contaminated
objects. As with other parvoviruses, this one is very tough to kill in the
environment. It can live for a long time on an object; therefore, disinfection
of objects that come in contact with your rats is necessary. This includes your
clothing; as with Canine parvovirus we can carry this disease on our clothing
and shoes, which makes us carriers of the disease. The best known killer of a
parvovirus at this time is household bleach mixed at one part bleach to ten
parts water.
Treatment:
As with any viral infection, there is no cure. If we use the guidelines for
treating dogs with Canine parvovirus we may be able to save our rats from this
disease; however, it's not likely to cause problems by itself. It usually
requires another disease to already be present in the rat, and then the
combination of the diseases is what may cause death. Because this is a rare
disease in laboratory rats, there isn't much treatment information available for
this disease. If a rat were stricken with the clinical symptoms of this disease,
it's possible that the rat could be saved with fluid therapy. Fluid therapy is
the major part of treatment for puppies infected with Canine parvovirus. Usually
the disease itself is not what kills the puppy dogs but the dehydration does.
An ELISA test can accurately diagnose this disease. If rats are tested for this
disease and infection is confirmed, the only way to eliminate it from your rat
colony would to bring in no more rats until all your rats have died off, then
start over. Don't start over until you've thoroughly disinfected everything.
When puppies are infected with Canine parvovirus, it's generally recommended
that you not buy a new puppy for at least six months after you've had a puppy
become ill or die. These viruses are so difficult to kill in the environment
that even if you have a puppy vaccinated, you still risk the occurrence of an
infection.
I've not found information to suggest that the same can be said for rats but
I've also not found any that implies that an infection couldn't happen within a
six month period.
This disease by itself is very likely not something to worry about. With the
other respiratory diseases being so prevalent, this is one more disease to think
about when your rat colony does break out with an epidemic.
Please Note: Although
Kilham Rat Virus does spread, research has determined that it is not lethal to
rats in the sense that Sendai and SDA are. It may, however, be lethal to
unborn babies and may be hazardous to newborns.
Quarantining new rats (a
must these days)
by Carole Nelson
I can't say enough about risking exposure of your own rat to a rat
from different colonies. It only takes one little rat to trigger a
serious illness like the Sendai and SDA virus, to name only a
couple. Rats from different colonies simply do not mix well
together. You really need to be careful to protect your own rat and
know the risks involved. Some viruses are airborne and can be
carried home by you on your shoes and clothes. Quarantining in
another part of your house may not even help.
The usual 2 week quarantine, may in fact not be enough
unfortunately. If your rat gets sick with in 2 weeks of exposure to
another rat get your rat to a vet fast because it could be a strain
of the dreaded SDA virus or Sendai virus which seems to be very much on
the rise these days. Your rat will need an antibiotic and lots of
love and care.
Some of the ways it is spreading is from stores that get them
from large warehouses, shows, swaps, loaning out your rats for
breeding purposes or simply getting them from more than one source
that has been in contact with other rats who have had it. Yours may
not be immune.
You might purchase a new healthy rat, yes, it could very well be
healthy.. BUT..... it also could be what is called a silent carrier
of a disease that you could be bringing home to your rats. This is
very sad for any pet lover to learn about when it is too late. I have
followed this for years now. I hear from so many about their pet rats
dying and have been researching everything I could find on it.
Some of this was first mentioned to me by a Canadian rodent vet,
who has had pet rats of her own. I didn't want to believe it back then. I was told that rats can carry many different things like viruses,
bacteria infections lice and mites so it is very important to quarantine.
Rats from different colonies simply do not mix well It took me a
few years to realize just how right she is.
I try now to no longer mix any of my rats with others people's rats
and only when absolutely necessary, about every 2 or 3 years get a new
outcross for my breeding plans.
It is far safer and I think I have nicer and healthier rats for doing
this. I practice proper line breeding and out crossing to strive for
better health, temperament and markings.
So far it has paid off and I can
trace back 14 generations in one of
my longest healthiest living rats.
It really could help big time, if more people would be responsible
and think ahead, plan what colour and type of rats they want or
would like to breed. They could certainly help to stop spreading the
viruses by at least getting all their breeding stock at once to
start with, get their new outcrosses only when absolutely necessary,
then maybe our little rats will be spared these horrible
heart breaking viruses. We can easily have social clubs, fun get
together and even rotate to one another's homes occasionally. It's
great fun to simply promote pet rats.
More Update on Sendai and SDVA
viruses
By Jan McArthur, R.V.T.
Yes, it's possible that you might breed your own rats that have been
infected with Sendai virus and/or SDA virus. Your own rats may develop an
acquired immunity to the diseases so they appear to be healthy.
However if you then take those rats to a show or rat swap you can
spread these diseases to other rats that have never been exposed to them.
This is why epidemics break out after shows.
I asked if Sendai virus could be cleared from a colony in two months
because when I wrote my Sendai virus article I could not find a
definitive answer to that specific question. I got the answer; it's
true Sendai virus can be cleared in two months in research
laboratories. Please don't let this get your hopes up if you are a
pet breeder who attends rat shows.
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.
Let's look closer at some of these statements.
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.
However, the isolation needs to be complete, including isolation
from aerosols or particulate generated from wild or loose rats, and
isolation from people who have recently handled rats from
enzootic ally infected colonies. This might be difficult if breeding
rats is your hobby and you visit rat shows.
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.
Once a colony is infected, clinically apparent illness is likely to
be minimal, since young rats (who get the sickest and die most
often) will be protected for their first few months of life by
maternal antibody. They will also get infected as soon as the level
of maternal antibody drops, and are likely to get less sick.
Your own colony may not exhibit any signs of disease, yours may
live out their life span even while they are sub clinically 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 enzootic ally 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...
I don't know how this can be any clearer. Mixing rats from different
colonies, from different areas can cause havoc in the pet rat.
People show dogs, cats, and farm animals but none of those animals
are ever brought together into one location without first having
vaccinations.
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. If you are a responsible
pet owner you'll do that.
A Statement From a DVM
In a normal, healthy adult
rat, you can expect both Sendai and SDAV
to be completely cleared in 2 months. 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.
When the colony is housed in an isolated situation, 2 months of
quarantine with cessation of breeding can indeed be expected to
eliminate either of these viruses from a colony. However, the
isolation needs to be complete, including isolation from aerosols or
particulate generated from wild or loose rats, and isolation from
people who have recently handled rats from enzootic ally infected
colonies. This might be difficult if breeding rats is your hobby and
you visit rat shows.
Once a colony is infected, clinically apparent illness is likely to
be minimal, since young rats (who get the sickest and die most
often) will be protected for their first few months of life by
maternal antibody. They will also get infected as
soon as the level of maternal antibody drops, and are likely to get
less sick.
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 enzootic ally 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...End of statement
Treatment for SDA Virus
There is actually no treatment for SDA because it is a virus. However, it
is very important that you aggressively treat the secondary infections.
You should treat every rat for severe respiratory infections as soon as
you know that your colony has been exposed to SDA to prevent as many
deaths as possible. A good choice for treatment is a combination of
Enrofloxacin (Baytril) and Doxycycline.
Note: Baytril and Doxycycline are not recommended for rats under 13 weeks
of age or for pregnant and nursing does.
Dosages:
Adults:
• Baytril - 5mg/kg to 10mg/kg twice per day
• Doxycycline - 2.5mg/kg to 5mg/kg twice per day
Rats under 4 months of age:
• Zithromax - 8.8mg/kg to 17.6mg/kg twice per day
or
• Tylosin (Tylan) - 10mg/kg twice per day
Pregnant and nursing does:
• Zithromax - 8.8mg/kg to 17.6mg/kg twice per day
or
• Tylosin (Tylan) - 10mg/kg twice per day
You can also treat bulging eyes with terramycin to help prevent
the eyes from ulcerating.
Terramycin Antibiotic Ophthalmic Ointment
References used:
The Biology and Medicine of Rabbits and
Rodents by: John E. Harkness and Joseph E. Wagner
Infectious Diseases of Mice and
Rats from: The National Research Council
The Merck Veterinary Manual Eight Edition
UC Davis School of Veterinary Medicine: Book
of Dogs
Diseases from: Nurse's Reference Library
Jan McArthur, R.V.T.
Microbiology :
Tortora, Funke, and Case
E-MAIL:
rats@lilratscal.com
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