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What is
Immune-Mediated Hemolytic Anemia?
Immune-Mediated Hemolytic Anemia (IMHA), is a disease in which the cat's
own immune system can become directed against its own red
blood cells.
What are red
blood cells?
Red blood
cells (also called
erythrocytes) supply
oxygen to the tissues of the body. They are also responsible
for it's red colour.
What causes
IMHA?
IMHA can be
classified as primary or secondary. Primary IMHA is caused by
an inappropriate immune response & no underlying cause can be
found autoimmune-mediated hemolytic anemia (AIHA).
Secondary
IMHA is brought about by a drug, toxin (onions, metal objects
containing zinc), cancer, parasite or
infection which adheres to the red blood cell, altering them
to the extent that the cat's own body no longer recognises
them as 'self' & initiates a humoral response (antibody
production). These antibodies stick to the red blood cells &
target them for destruction (hemolysis) by the spleen.
Neonatal
isoerythrolysis (NI) is another cause of IMHA seen in nursing
kittens. This occurs when
a kitten is born with type A blood is born to a queen with
type B blood. The queens first milk
is known as colostrum. Colostrum is produced in the first 48 -
72 hours after birth & provides newborns with essential
nutrients & antibodies which protect the kitten from
infection. However, in this case the antibodies attach to the
kitten's red blood cells, causing their destruction.
What are the
symptoms of IMHA in cats?
Symptoms vary
depending on the severity of the anemia & may appear suddenly
or gradually over time. They may include;
How is IMHA
diagnosed?
Your
veterinarian will perform a physical examination of your cat &
will want to know your cat's history & any symptoms it may
have been displaying.
Additionally,
your veterinarian will perform some tests, which may include;
Coombs
test: Also known as antiglobulin test or direct antibody
test, this test is to detect the presence of antibodies
which can bind to the surface of red blood cells.
Packed cell
volume (PCV): Measures the percentage of a sample of blood which is occupied
by red blood cells.
Complete
Blood Count (CBC): A series of tests which
evaluates the cellular components of blood (red blood cells, white blood cells
& platelets).
Blood
Smear: A small drop of blood is spread over a glass
slide & examined under a microscope on a slide. The
presence of spherocytes & agglutination (red blood cells
clumping together) on a blood smear
are indicative of IMHA.
Other tests
will be necessary to find out if there is an underlying cause
of IMHA. This would include blood tests to look for the
presence of parasites or infection.
An X-ray may
be performed to determine if the anemia is cause by a metal
object containing zinc or cancer.
How is IMHA
treated?
Prognosis
& treatment depend on the underlying cause of the IMHA & the
severity.
-
Where
possible, find & treat the underlying cause of the IMHA.
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Corticosteroids to suppress the immune response, most
commonly prednisone is prescribed.
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Supportive
care such as intravenous fluids where necessary.
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Blood
transfusion: If the red blood cells have dropped to critical
levels then a blood transfusion may be necessary.
Please note:
The medical
articles on this site have not been written by a
veterinarian & should not be considered a replacement for a
veterinarian visit. The articles are provided for
informative purposes only.
Always seek
immediate veterinary advice for any problems (health or
behavioral) in your pets.
While great
care has been made in the creation of these articles, we
cannot guarantee the accuracy or omissions on these pages.
If in any doubt whatsoever, seek professional medical
advice.
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