Kidney Problems
by Doc Skinner
August, 1997
Kidney problems are a growing concern for beaglers as well as
other pet owners. Blood urea nitrogen, is the quick blood test
performed by veterinarians to determine if the kidneys are
clearing the blood of urea nitrogen. This is a major componenet
of protein metabolism. If the kidneys are not doing their job,
the B.U.N will indicate it with a high reading. A more indicative
test for kidney function is a creatinine test. A very high
creatinine test is usually suggestive of irreversible kidney
failure. Unfortunately there is no quick test for creatinine, it
must be sent to a diagnostic laboratory.
Kidney failure and nephrotic (kidney) syndrom must be
differentiated for appropriate treatment. Nephrotic syndrome is
characeterised by a loss of serum protein due to kidney disease
that increases glomerular permeability. In other words, protein,
especially albumin, that would be filtered and saved by the
kidneys is lost through the damaged glomeruli. This disease is
often immune meiated as I will explain. Immune mediated
glomerular nephritis, or I.M.G.N., can be a primary disease or
the result of a related systemic disease. Chronic kidney disease
is seen in older dogs as an aging problem. I.M.G.N. is often seen
in younger animals. A client lost two Field Champion beagles,
mother and daughter, both before the age of three. This gives
some credence to one cause being genetic.
Some systemic diseases that can bring on I.M.G.N. are chronic
infection, i.e. dental infections, diabetes, hypothyroid levels
or poisonings. As a primary condition the cause my be unknown or
inherited as is familial amyloidosis in humans.
Dogs suffering from I.M.G.N. are presented with weight loss,
sometimes swollen limbs and abdomen, loss of appetite, vomiting,
labored breathing and weakness. The animal must be worked up to
determine if the cause is primary or secondary. Many of the above
symptoms are due to a major loss of protein through the kidneys
by way of the urine.
Protein in the urine can occur without kidney trouble as in some
forms of cancer. However in such cases there is an excess of the
same protein in the serum and the urine. This is known as pre
renal proteinuria. Post renal proteinuria is protein that enters
the urine after it leaves the kidneys usually from the bladder or
lower tract, it never causes a hypoproteinemic condition. Protein
in the urine coming from the kidneys can be either functional as
seen in dogs after strenuous exercise or pathologic due to
glomerular or tubular inflammation or damage.
Albumin, the protein lost with I.M.G.N., is produced in the liver
so it must be determined that the hypoalbuminemia is not due to a
liver problem or a loss through the G.I. system. Globulin
molecules are larger than albumin and so are not usually lost as
readily through the kidney as the smaller albumin molecules. If
the sreumalbumin and globulin are low it may be due to a
gastrointestinal loss.
High cholesterol levels occur with I.M.G.N. but it can also occur
in other diseases such as hypothyroidism, Cushings disease, liver
diseases and pancreatitis, these latter conditions must be
excluded diagnostically.
The hypoproteinemia of I.M.G.N. may cause swollen limbs and
belly. To put it plainly, protein helps to hold part of the fluid
in the blood vessels. If the level of protein in the blood
vessels drops, the fluid leaves the vessels accumulating in
tissue as swollen legs or abdomen.
Some preexisting conditions that produce I.M.0.N. are heartworms,
tick borne infections such as Ehrlichiosis, and Lyme disease as
well as pyometra and chronic infections.
Treatment of I.M.G.N. is difficult because the damage may be
overwhelming. Although immune mediated, attempts to prevent
antibody production by using immunosupressive drugs has proven of
no value. Platelets cause a lot of the inflammation in I.M.G.N.
not only by causing clumping and intraglomerular clots but also
by their release of certain substances. To help counteract
platelets’ role, low doses of aspirin, 5 mg./kg. every 12
hours is suggested. An increase of dietary fatty acids also
reduces the inflammation of I.M.G.N. This is a complex role
involving prostaglandins and arachidonic acid metabolism.
Thrombosis or blood clots also are reduced in dogs on marine fish
oils.