Exam 3 - Companion Animal Anemia: Mechanisms & Work-Up Flashcards
what is anemia?
decrease in the amount of total RBC mass (O2 carrying)
what is the consequence of anemia?
decreased O2 carrying capacity
what does calculated hematocrit depend on?
MCV (mean corpuscular volume), agglutination, & machine accuracy
what are the species differences & things relative to the patient between dogs & cats when it comes to parameters of anemia?
dogs are anemic at a higher hematocrit than cats
young animals have a lower hematocrit
greyhounds have a higher hematocrit
what are the 2 classifications of anemia based off of mechanism?
regenerative & non-regenerative
what is the exception to regenerative anemia when it comes to loss & lysis?
early hemolysis/lysis
too soon to see a regenerative response - look at 3-5 days for one
what are the 2 mechanisms listed as causes for regenerative anemia?
- loss
- lysis
what are the 2 mechanisms listed as causes for non-regenerative anemia?
- systemic/inflammatory response - decreased production
- primary bone marrow disorder - decreased production
how do you differentiate between loss & lysis in regenerative anemia using total solids/total proteins?
in loss - decreased total solids, total solids from PCV/TS, total protein from the CBC, & albumin on chemistry panel
in lysis - total solids often within normal limits or may even be increased from dehydration (primary process)
what is the exception for a decreased TS in a regenerative anemia due to loss?
very acute bleeding!!!
what are some clin path abnormalities seen on a patient with non-regenerative anemia caused by a systemic/inflammatory response?
isosthenuria or azotemia
what are some causes of non-regenerative anemia attributed to a systemic/inflammatory response?
chronic inflammatory disease
hypothyroidism
chronic kidney disease - decreased responsiveness to EPO & decreased iron transport
what are some causes of non-regenerative anemia attributed to a primary bone marrow disorder?
toxicity
neoplasia - myelophthesis
immune mediated
infectious diseases - fungal or viral
what is an important clue seen on a CBC that lends support to a primary bone marrow disorder causing a non-regenerative anemia?
bicytopenia or pancytopenia
what is an important clue seen on a CBC that lends support to a primary bone marrow disorder causing a non-regenerative anemia?
bicytopenia or pancytopenia
what are some causes of non-regenerative anemia attributed to a pre-regenerative anemia?
acute hemorrhage or hemolysis
if investigating pre-regenerative anemia as a differential for a non-regenerative anemia, what should you do?
establishing chronicity is very important!!!
recheck serial lab work
what are some external causes of hemorrhage?
trauma
mucosal surfaces - GI, urinary, & nasal
what are some internal causes of hemorrhage where the RBCs are reabsorbed?
-body cavity (peritoneum, thorax, & pericardium)
-intraorgan (CNS, skin, +/- lungs)
-skin, often petechiae & ecchymoses
what is involved in extravascular hemolysis destroying RBC?
immune-mediated process involving the reticuloendothelial system
destruction within the spleen
what is involved in intravascular hemolysis destroying RBC?
-immune-mediated
-toxicity (drugs, zinc toxicity, metabolic)
-infectious: look for organisms in the RBC or a secondary immune-mediated process
what dog breeds have an associated cause of hemolysis?
springer spaniels & basenji dogs
what is the breed-associated cause of hemolysis in springer spaniels?
phosphofructokinase deficiency - lack of enzyme necessary for the stabilization of RBC
what is the breed-associated cause of hemolysis in basenjis?
pyruvate kinase deficiency - lack of enzyme necessary for the stabilization of RBC
what cat breeds are associated with osmotic fragility syndrome causing hemolysis?
oriental cat breeds, abyssinians, & somalis
what color can be seen on mucus membranes that could be concerning for hemolysis?
yellow/icteric
what are the categorizations of severity of anemia?
mild: > 28%
moderate: 18-28%
severe: <18%
what is the difference of microcytosis & macrocytosis when it comes to interpreting a CBC for an anemic patient?
microcytosis - small RBC
- Fe deficiency anemia or abnormal Fe metabolism
- breed specific (toy poodles, akitas)
macrocytosis - large RBC
- most likely regenerative
- also seen in FeLV disease
what measures the density of RBC?
MCHC - hemoglobin content
if an animal has an Fe deficiency anemia, what would you expect the MCHC to be?
hypochromic
what is the gold standard for reticulocyte counts?
actual or absolute count
what is the formula for the actual/absolute reticulocyte count?
total RBC count * reticulocyte %
what is the cut-off value for a non-regenerative anemia when looking at reticulocyte counts for dogs & cats?
dogs: <60,000
cats: <50,000
when looking at feline reticulocytes, what is the difference between aggregate & punctate types?
aggregate - younger reticulocytes
punctate - older/more mature
when looking at a CBC of an anemic patient, what do you think of with a low total solids? what if it’s normal or high?
if low - consider hemorrhage
if high - inflammatory disease or chronic hemorrhage
when looking at a CBC of an anemic patient, why may a thrombocytopenia be important?
hemorrhage - consumption
might be the cause of bleeding if severe (IMTP leading to blood loss)
T/F: you can have platelets that are WNL with certain rickettsial diseases
true
if albumin, globulins, & cholesterol are all low on an anemic patient, what should you consider?
gi bleeding
if albumin is low on an anemic patient, what differentials should you consider?
- gi bleed
- PLN
- hepatic disease
if an anemic patient has hyperglobulinemia, what differentials should you consider?
- infectious disease
- inflammatory process
- neoplastic process
if an anemic patient has hyperbilirubinemia, what differentials should you consider?
potential pre-hepatic hemolysis
why is it important to visually inspect the serum of an anemic patient?
tells you if there is discoloration present
what does it mean if the serum of an anemic patient is yellow or orange in color?
bilirubin - hemolysis
what does it mean if the serum of an anemic patient is red in color?
hemoglobin is present - intravascular hemolysis
what does it mean if the serum of an anemic patient is lipemic?
maybe endocrinopathy
what is the most common cause of hemolytic anemia in cats?
mycoplasma & cytauxzoon felis
if you suspect babesia causing anemia in your patients, where should you sample for a blood smear?
ear tips or nail beds
what is the most common abnormality seen on a blood smear of an anemic patient?
thrombocytopenia
what dog breeds are known to be associated with babesia causing anemia?
greyhounds & staffordshire terriers
why are blood smears helpful in using for an anemic patient that you suspect has an infectious cause?
helpful for detecting infectious organisms in the RBC - babesia!!!
what do spherocytes indicate on a blood smear?
lack of central pallor & microcytic - indicates macrophage destruction of cell & essentially always indicates immune-mediated destruction/extravascular hemolysis
what do schistocytes indicate on a blood smear?
broken fragmented cells - HW disease, DIC, & splenic disease
what do heinz bodies on a blood smear indicate? what are the agents that cause these in dogs & cats?
oxidative damage to RBC
dogs - onions
cats - acetaminophin
what do echinocytes on a blood smear of an anemic patient indicate?
snake bite envenomation
what does basophilic stippling on a blood smear of an anemic patient indicate?
lead toxicity
what do nucleated RBCs on a blood smear of an anemic patient indicate?
regeneration, primary bone marrow disease, or splenic disease
if positive, a saline agglutination test on an anemic patient is diagnostic for what disease?
immune-mediated hemolysis (IMHA)
how do you perform a macroscopic agglutination test?
no microscope required - mix saline & blood on a slide and gently rock
look for clumping
how do you perform a microscopic agglutination test? what disease process must you differentiate from agglutination in this test?
use a microscope! mix saline & blood & look for clumps
rouleaux
spherocytes in a blood smear of an anemic patient is almost entirely pathognomonic for what disease?
IMHA
microcytic, hypochromic anemia is almost entirely pathognomonic for what disease?
iron deficiency anemia - chronic external blood loss
microcytosis without anemia is not the same
what 3 components of the urinalysis of the anemic patient are the most important to evaluate?
- pigmenturia
- urine specific gravity
- proteinuria
what 3 kinds of pigmenturia can be seen in the anemic patient? what do they indicate?
- bilirubinemia - extravascular hemolysis
- hematuria - decreased platelets, thrombocytopathia (dysfunction)
- hemoglobinuria - intravascular hemolysis
must differentiate from myoglobinuria - spin down urine to see if RBC will pellet
if there is proteinuria present on the urinalysis of an anemic patient, what may this indicate?
infection or inflammation
what may be seen on USG of an anemic patient?
inadequate concentration/isosthenuria - consistent with chronic kidney disease
when you suspect a GI bleed, why do a fecal?
whipworms, hookworms - big culprits
what are the pros & cons of VCE in a patient with a suspected GI bleed?
less invasive & may be able to see lesions in jejunum/ileum
weight cut off - can’t do in small dogs, & expensive
what 3 tests should you run if you suspect there is an immune-mediated disease, such as IMHA or IMTP, leading to hemorrhage?
coombs’ test - looks for antigen-antibody complexes
flow cytometry for RBC or platelet surface antibodies
infectious disease testing - 4DX, babesia
why would an abdominal ultrasound be helpful in working up an anemic patient?
better look at architecture - look for ulcers, masses, & intestinal wall thickening
when would you consider an upper/lower gi endoscopy in an anemic patient?
bleeding ulcer - to confirm ulcer, biopsy, & neoplasia or zinc penny ingestion
when are bone marrow exams indicated in anemic patients?
- severe anemia not explained by chronic disease & non regenerative
- > 5 days anemia & still non-regenerative
- concurrent cytopenias with a non-regenerative anemia
why does heart rate increase when O2 content is going down?
cardiac output = HR * stroke volume
cardiac output contains O2 content of RBCS, so the more that O2 drops, cardiac output increases to try & get oxygen to the body
what are the transfusion guidelines for severe anemia of <18%?
often requires blood - can be case dependent as chronic severe anemias often are adjusted to their low RBC
what are the transfusion guidelines for Hct or PCV <12%?
definitely requires transfusion - need to consider if the animal has been transfused before
need to also consider mechanism of deficiency
what blood product is best for treating VWF?
cryoprecipitate
what blood product should be used for hemorrhage or potentially clotting factor problems?
- whole blood or plasma is the most appropriate with fresh whole blood being associated with better survival
what blood product should be used for hemolysis or decreased production?
- packed red blood cells are the most appropriate, less volume required & less immunogenic
if a dog has been transfused before, you must what?
cross match!!!
why is it important to blood type & cross match cats that need a blood transfusion?
type b has a strong reaction to type a causing a hemolytic anemia
for every 1 ml/kg of pRBC, PCV will increase by how much?
1%
if your pet is at 15%, using pRBC to raise PCV by 8-10% for a 10kg dog would be what?
80-100 mls of pRBC
what is the difference between using pRBC & whole blood for a transfusion?
whole blood takes 2x the amount than pRBC - so for every 2 ml/kg of product, PCV raises by 1%
if your pet is at 15%, using whole blood to raise PCV by 8-10% for a 10kg dog would be what?
180-200 mls whole blood needed
what are some contraindications to pursuing a blood transfusion?
not cross matching to any units
severe heart disease - although, sometimes life & death, so go very very slow
what is the ‘standard transfusion’ reaction? what should you do? what are some other complications?
increased temp - slow down the fluid rate
transfusion related acute lung injury & transfusion associated circulatory overload
for a normovolemic patient, what is the transfusion rate?
10 ml/hr
for a hypovolemic patient, what is the transfusion rate?
30 ml/hr
for a patient at a high risk of overload (cardiac disease), what is the transfusion rate?
ideally no more than 5 ml/hr
what is the recommended start in regards to rate for all transfusion patients?
can always start at 1/2 the recommended rate for the first 1/2 hour then increase
what monitoring should be used for transfusion patients?
monitor HR & temperature every 5 minutes for the first 30 minutes & then span out to every 15 minutes for the remainder of the transfusion
