Anemia =a condition of reduced
oxygen carrying capacity of
Erythrocyte disorders are frequently
diagnosed in the dog and cat and may
be associated with:
1. Decreased production of RBC’s
2. Increased destruction of RBC’s
3. Inappropriate loss of RBC’s
A systemic diagnostic approach to anemia
is necessary and should include:
A good history
Complete blood count
Blood film / slide analysis
•Treatment should be aimed at correcting the primary
disorder and supporting the patient.
•IT IS IMPORTANT TO ESTABLISH WHETHER THE
ANEMIA IS REGENERATIVE OR NONREGENERATIVE.
• Reticulocyte counts are evaluated to determine if the
anemia is regenerative or nonregenerative.
Regenerative Anemia :
• Increased reticulocytes, nRBCs.
aniscocytosis, polychromasia & Howell-
• Indicates the bone marrow has
responded to a demand for RBCs by
increasing production and releasing
into the circulation adequate numbers
of immature RBCs = polychromatophils.
• Bluish to reddish-blue cytoplasm
• Slightly larger than mature RBCs
• When stained with New
Methylene Blue = Reticulocytes
• Irregular net-like structures in
polychromatophils when stained with
New Methylene Blue = reticulum
• Reticulum is irregular clumps of
ribosomal RNA and organelles, such
• Most species only have one form of
reticulocyte, however cats have TWO.
Decreased Reticulocyte Count ;
Caused by inadequate production of
RBCs by bone marrow.
Canine Reticulocytes when stained with
New Methylene Blue
NOTE : Polychromatophils are
larger than adult RBCs
•Puncate v. Aggregate
•The aggregate reticulocytes mature into
punctate reticulocytes within 12-24
hours; punctate reticulocyte circulate for
at least several days (7-10 days) before all
the RNA is lost.
•The reticulocyte count in cat blood
should only include the percentage of
aggregate reticulocytes; punctate
reticulocytes are not counted as they do
not reflect the most recent bone marrow
response (e.g. an anemic cat with only
punctate reticulocytes is not actively
regenerating at this time, but has shown
some bone marrow regeneration in the
past 7-10 days).
Hemorrhage = the escape of blood from a
ruptured vessel. Hemorrhage can be external
• Most common cause is trauma
• Can also be caused by thrombocytopenia :
petechial hemorrhages on earflaps, mucous
membranes, and on nonhaired areas such as
•TX : steroid tx, plasma or whold-blood
transfusions, and avoidance of trauma.
Iron is important in the body because it
is the main constituent of hemoglobin.
• Caused by chronic external blood loss.
Severe flea infestations, GI parasites, gastric
ulcers and bleeding tumors can cause
significant blood loss over time.
•The iron and hemoglobin lost with this
external bleeding result in the formation of
altered RBCs and decreased life span.
TX: correct blood loss + iron supplements
Hemolytic Anemia = the increased destruction of
•Caused by immune components attaching directly or
indirectly to the RBC membrane, altering its structure.
•The body, in an attempt to regain homeostasis, begins to
remove these altered cells.
•In cats, the most common cause of hemolytic anemia is
haemobartonellosis / mycoplasma, a blood born parasite.
•In dogs, the most common cause is an underlying
Oxidation and denaturation of hemoglobin in
RBCs result in the formation of protuberances
from the RBC membrane called Heinz Bodies.
The most common cause of Heinz body
formation in the dog is onion toxicity.
Acetaminophen (Tylenol) toxicity also results
in Heinz body anemia in dogs and cats.
•The specific cause of IMHA is unknown.
•Accelerated RBC destruction occurs because of the
presence of antibodies that attach to the RBC membrane.
•These cells are removed by the immune system, resulting in
•Found most commonly in dogs 2-8 yrs of age, poodles, OE
Sheepdogs, Irish setters and cocker spaniels.
•4X more prevalant in females than in males.
•30% to 40% of all dogs will die despite TX.
•TX : Glucocorticoids!! & meds to prevent
gastric ulceration 2° to glucocorticoid TX .
•Relapses are common.
•On blood slide evaluation : marked
autoagglutination, spherocytes, hemolyzed
• Normocytic (RBCs of normal size)
• Macrocytic (RBCs larger than normal)
• Microcytic (RBCs smaller than normal)
• Hypochromic (reduced
• Normochromic (normal
Macrocytic (large Rbcs), hypochromic
(reduced hemoglobin concentration)
anemia suggests REGENERATION.
Iron deficiency also results in
hypochromic anemia, but is characterized
by microcytosis (small RBCs).
Most other types of anemia are