|This article is from the Winter 2000
AFRMA Rat & Mouse Tales news-magazine.
Kidney Stones vs. Kidney/Bladder Infections
5-week-old Tailless Rat with Bladder Stones
Helen Pembrook, Sky Valley, CA
Q The subject at hand is a little
Siamese Tailless male born 4-9-99. He was purchased at the
May AFRMA show on Saturday 5-15-99. He passed health check
in the morning and seemed healthy when I picked him up at
about 2:00. At 4:30 or so he was rattling terribly to the
point where I could feel it with my hand and hear the rattle
2 feet away. He seemed better that evening and the rattle
was gone on Sunday, so I assumed his problems were due to
stress. On Monday he showed drastic signs of weight loss:
his hips were greatly pronounced and his sides sunken in.
When I examined him, I felt a hard long lump in the center
of his belly. My initial thought was an intestinal or
bladder blockage or maybe a tumor or cancer, but I was not
familiar with rat anatomy at the time so I wasn’t sure.
I noticed that when I watched him, he would eat a little of
the treats I gave him but would not drink anything. On
Tuesday his belly was bloated and the long lump was larger.
On Tuesday early afternoon he died. The necropsy showed that
there was a lot of fluid throughout the abdominal cavity and
that the bladder was blown up like a balloon to about the
size of a grape, 1 inch long by ½ inch wide. All of the
other organs appeared to have good color and be healthy
except the kidneys which were a little bit gray. We assume
this is probably the result of the urine being so backed up.
Upon further examination, it was discovered that there were
7–10 small grain-of-sand-sized kidney or bladder stones
in the bladder after it was emptied of fluid. The assumption
thus far is that a stone blocked the urethra so that the
animal could no longer urinate.
A This is very interesting. There
are a variety of causes of urolithiasis in animals. With the
animal being so young, I wonder about genetic defects linked
to the taillessness. The best way to try and understand what
happened would be to have sent the kidneys and bladder for
histology and have the crystals examined to determine the
exact type. Crystals can be formed in the kidneys or in the
bladder. Diet, disease, and hydration can all contribute to
their formation. Knowing what type of crystal(s) are present
can help in determining the underlying cause.
Another thought is that in animals that are genetically
Tailless, there are often problems with urinary or bowel
movement control. It is likely that the crystals plugged the
urethra, but bladder atony could have contributed. I would
also have submitted the urethra for histology. Actually, I
would have had the entire rat examined for histology in
cases such as these.
Following are some additional questions and answers regarding kidney stones vs. kidney/bladder
Case scenario: 3 male rats in one
cage all less than 1 year old; blood in urine is noticed on
one of the solid metal shelves in the cage and it is
pinpointed as to which rat is doing this, rat goes to vet,
vet thinks the problem is cancer, vet takes a sample of the
rat’s urine and sends in for a pathology report, report
comes back NOT cancer — just an infection, rat acts
fine throughout this whole ordeal, owner treats rat for
infection, blood in urine goes away, all rats in cage now
happy and healthy.
Details: all rats are fed lab blocks with an occasional piece of washed vegetable or fruit. They are
on CareFRESH™ bedding, get cleaned once a week (the cage is very large for 3), get
bottled water to drink, and played with often.
Q How do rats get kidney stones?
The cause is varied and can be from substances in the diet, kidney infections, etc. The kidneys are giant
filters, and in the process of excreting urine (water, urea,
and dissolved salts — normal function of the
kidney) sometimes precipitates form. Think of rock candy
which is formed by a concentrated solution of sugar in
water. The precipitates form when the urine pH is high,
water content low, and precipitate content high. Cats get
this most commonly from diets high in Mg or ash.
Q How do rats get kidney/bladder infections?
In most cases, urinary tract infections are caused
by bacteria ascending from the urethra to the bladder and
then to the kidneys themselves. Some cases are caused by
sepsis (bacteria throughout the body) or in males with a
prostatitis (infection of the prostate). Animals with
chronic kidney stone production are more prone to chronic
urinary tract infections because of the chronic irritation
of the lining of the urinary tract.
Q Can what rats eat/not eat cause a problem?
There is no specific dietary factor indicated in rodents that I am aware of.
Q How do you treat the problem(s)?
For simple first-time infections, I use a general
oral antibiotic for 2–3 weeks. In protracted cases or
repeat cases, I do a urine culture and sensitivity and
choose the suggested antibiotic. No specific antibiotic is
given because this is not something anyone should treat
themselves and depends on the situation.
Q What are the symptoms in the rat?
In any species, the most common symptoms are
increased frequency urination (and water consumption), pain
or straining on urination, blood in urine. Incontinence is a
common symptom in dogs and cats. In cases where there are
kidney or bladder stones or fine granular precipitate, the
urethra may become blocked and then it is a life threatening
situation if the blockage is not removed. This is most
common in male cats because of the small diameter of the tip of the urethra.
Q Is the behavior different in the rat depending on the problem (i.e. does
the rat act fine for a kidney/bladder infection vs. the rat acts sick/off with a kidney stone?)
No, it really depends on the severity of the
situation irregardless if there are stones/precipitates or
solely urinary tract infection.
Q Is it more common in one sex?
I have seen this more frequently in male than female rats.
You also have to remember that as rats age, they
get a condition of the kidneys called “Chronic
Progressive Nephropathy” and is associated with a high
protein diet. This disease results in inflammation,
fibrosis, and destruction of the filtration apparatus of the kidneys (glomerulosclerosis).
Q What kind of tests does a vet run to determine what is wrong with the rat?
A urinalysis is the usual test with cytologic examination of centrifuged urine to look for bacteria,
crystals, blood, tumor cells, etc. For discrete stones, a radiograph or ultrasound is sometimes used if stones are
suspected and none are palpable.
Q What are the chances of it being cancer rather than just an infection/stone?
No statistics are known. Cancer in any species becomes more suspect in an older animal.
Q Many have asked if Tylan would be used
to treat a kidney infection or other general infections?
No, the strains of bacteria that infect the
respiratory tract are different from those that infect the
urinary tract (in most cases) and usually require specific antibiotics.
Q What about if someone sees blood in
the urine in a couple of their male rats once in a while.
Should they take the rat to the vet, keep an eye on the rat
for any change in behavior, treat themselves, or something else?
Anyone who sees blood in the urine of their
animals should take them to the veterinarian, even if there
are no other symptoms. Blood in the urine is never normal
and means that there is bleeding somewhere there
shouldn’t be bleeding.