SAM II Final Exam - Hematology Flashcards
T/F: The majority of dogs with IMTP have a platelet count of <20,000/uL
True
A doberman has been diagnosed with vWD. There are a number of therapies available for managing hemorrhage crises or used in the anticipation of surgery in this disease. Which is not a treatment option?
- Fresh whole blood
- Plasma
- Fresh frozen plasma
- Cryoprecipitate
- Desmopressin
Plasma
- Plasma has no value in blood transfusion at all.*
- Fresh whole blood would be helpful, but you would be increasing the risk of overperfusion. Fresh frozen plasma would be ideal. Cryoprecipitate would be the best option (has a very high concentration of vWF and factor 8). Desmopressin will have an onset within 30 minutes and a duration of action of 2 hours, where it will increase the release of vWF from platelets and endothelium
In the treatment of IMHA, what is the main benefit of using Mycophenolate mofetil instead of Azathioprine?
Mycophenolate does not cause bone marrow suppression
Azathioprine does.
If you note petechiations on the ventrum, perineal area, and/or gums, is this more likely a primary or secondary hemostatic disorder?
primary
A dog presents with a 24 hour history of weakness and anorexia. Clinical exam: pale mm and tachycardia. The owner complaint is red urine. Hematology detects a moderate anemia (PCV 25%), non-regenerative, normocytic, normochromic. The serum is red discolored. What is your likely diagnosis?
- Intravascular hemolytic anemia
- Bone marrow destruction
- Blood loss anemia
- Extravascular hemolysis
Intravascular hemolytic anemia
- Even though this dog is non-regenerative, there has been a massive decline in its PCV. This dog is showing signs of shock as the result of a hemolytic crisis (something that has dramatically decreased its oxygen capacity).*
- This could be anything that leads to lysis of the RBCs, including Heinz body anemia and IMHA*
Spherocytosis is a hallmark of __________ disease
Spherocytosis is a hallmark of immune-mediate disease
Due to immune opsinisation of RBC and piecemeal removal of the membrane
The most common blood type in cats is:
Type A
-
Blood groups: A, B and AB (MIK)
- Type A is most common
- Type B varies in frequency depending on the breed
- AB is rare
- Naturally occurring alloantibodies
- Need to be blood typed before first transfusion
- Crossmatching must be performed before subsequent transfusions
T/F: Polychromasia is a hallmark of regeneration
True
A dog presents with respiratory distress due to hemothorax. Which of the following potential etiologies is incorrect?
- Warfarin toxicity
- Advanced liver failure
- Hemophilia
- Angiostrongylus vasorum (French heartworm)
- Thrombocytopenia
thrombocytopenia
- It’s likely that the hemothorax was the cause of the thrombocytopenia, not the other way around. Additionally, even if this happened spontaneously, low platelet count or low platelet function is incapable of causing a massive cavity bleed.*
- This has to be a secondary coagulopathy.*
What are the two forms of reticulocytes in cats?
aggregate and punctate
The only way to prove a dog has Evan’s Syndrome is by the use of:
flow cytometry
T/F: Uremia may cause thrombocytopathy
True!
While not widely available, this test is currently the most sensitive and specific way to test and diagnose Vitamin K antagonism:
PIVKA
- Protein Induced by Vitamin K Absence*
- PIVKA can detect coumarin or warfarin toxicity as early as 12 hours after ingestion*
With marked thrombocytopenia, platelet count is less than _________
50,000
With marked thrombocytopenia, platelet count is _< 50,000/uL_
- Rule out infectious diseases
- Rule out neoplasia
- Bone marrow assessment
- (AntiPLT Ab tests not routinely available)
- Dx = Autoimmune Thrombocytopenia if all 2˚ causes ruled out
You suspect IMTP in one of your patients, so you send some blood out for PCR to help rule out infectious disease. What drug might you start the patient on while you’re waiting for the PCR results?
doxycycline
Immunosuppressive drugs are the key to treating ITP; however, because results of serology for infectious causes of immune-mediated thrombocytopenia may be delayed, concurrent treatment with doxycycline is often initiated with immunosuppressive drugs.
What transfusion products would be indicated in the case of thrombocytopenia?
fresh whole blood, platelet rich plasma, platelet concentrates
What is your first step of treatment if you note signs of a transfusion reaction?
STOP THE DAMN TRANSFUSION
- Stop transfusion immediately
- Record everything!!!!
-
If histamine-related signs, give:
- Antihistamine +/‐ Dexamethasone
-
If anaphylactic shock:
- Oxygen +/‐ artificial ventilation
- Adrenaline IV
- IV fluids
- Antihistamines (e.g. Piriton) and H2 blockers
- Dexamethasone
____ mL/kg of donor blood will raise recipient PCV by 1%
2.2 mL/kg
2.2 mL/kg of donor blood will raise recipient PCV by 1%
What are some causes for an increased MCV?
- Regenerative (reticulocytes)
- Toy breeds
- Cats with FeLV and myeloid dysplasia
- Artifact (agglutination)
The image below is the ventral abdomen of a Miniature Schnauzer. Is this an example of primary or secondary hemostasis?
primary hemostasis
Note the petechiation. This is a thrombocyte number or function abnormality
Which glucocorticoids are most commonly used to treat IMHA?
prednisone and dexamethasone
- Prednisone 2mg/kg/day
- Dexamethasone 0.25-0.5 mg/kg/day
T/F: Blood transfusions raise the patient’s platelet count
False
If we repeat a hematology after receiving a platelet transfusion, there will be no change in the platelet count, but whole blood may contain enough platelets to stop hemorrhage
The mainstay of treatment for IMHA is __________ therapy
Immunosuppressive
glucocorticoids are our go-to drugs
If you note hematomas, hemarthrosis, or bleeding into cavities , is this more likely a primary or secondary hemostatic disorder?
secondary
What is the ideal drug combination for thromboprophylaxis in dogs being treated with steroids for immune-mediated disease?
Aspirin + Clopidogrel
T/F: Whenever your patient has a platelet production abnormality, it is always accompanied by a bicytopenia or pancytopenia
True
T/F: The combination of Vincristine + Prednisone may be recommended as a treatment for IMHA
False
The combination of Vincristine + Prednisone may be recommended as a treatment for _IMTP_
If you strongly suspect IMHA in a dog and you want to confirm it, and it is ISA-negative, what test would you perform?
Direct Coomb’s Test
- Direct Coomb’s test (direct antiglobulin test-DAT), which detects antibody and compliment attached to the RBC membrane.*
- A diagnosis of IMHA should not be based on the Coombs test alone*
- ↓ platelet count
- ↓ PTT and ↑ PT
- ↓ fibrinogen
- ↓ antithrombin
- ↑ D-dimer or FDP
If you have two or more of the above criteria, you can make the diagnosis of:
DIC
disseminated intravascular coagulopathy
T/F: Heinz bodies may be normal in cats
True
~1% of RBCs in cats will have Heinz bodies. To determine if they’re pathologic or not, it is important to look at the amount of Heinz bodies and the SIZE of the Heinz bodies
A collapsed dog with tachycardia has IMHA, with PCV: 10%, TSP: 72 g/L, ISA: positive. What blood product would you transfuse?
- Whole blood
- Fresh whole blood
- Packed cells
- Fresh frozen plasma
- Platelet rich plasma
Packed cells
When is an oral buccal mucosal bleeding time test indicated?
Patient with hemostatic abnormalities but platelet count higher than 70,000/μL
Regarding IMTP therapy, which statement is incorrect?
- Initial therapy includes prednisolone at immunosuppressive dose
- Vincristine will decrease hospitalization time
- Human immunoglobulin infusion is considered the standard of care in severe thrombocytopenic patients at risk of bleeding-less bleeding episodes and shorter hospitalization than vincristine
- Thromboprophylaxis (Clopidogrel or aspirin) is generally started on day three of IMTP therapy
Human immunoglobulin infusion is considered the standard of care in severe thrombocytopenic patients at risk of bleeding-less bleeding episodes and shorter hospitalization than vincristine
-
Explanation:
- 1. Immunosuppressive therapy WILL be our first line of treatment for IMTP
- 2. There is evidence to show that Vincristine will benefit the patient and decrease hospitalization time
- 3. Human immunoglobulin is not shown to be any better than vincristine (they work equally well). Since human immunoglobulin is a biological product and is expensive, it is now considered that Vincristine is a very good alternative
- 4. On day 3 of treatment for IMTP, there is a massive rebound of platelets (which can become aggregated very quickly). These dogs are at high risk of developing clots, so thromboprophylaxis is definitely recommended.
A dog has been diagnosed with IMHA, This dog is a diabetic. What would be your immunosuppressive of choice?
- Prednisolone
- Mycophenolate mofetil
- Cyclosporine
- Azathioprine
Mycophenolate mofetil
A diabetic patient should not be put on prednisolone (we would create a lot of resistance using corticosteroids). Azathioprine is a steroid-sparing drug, but is not very effective on its own. Cyclosporin is a promising drug for treating IMHA, but its onset of action is not as fast as mycophenolate
Which of the following is incorrect regarding Systemic Lupus Erythematosus (SLE)?
- A multisystemic disease characterized by multiply autoantibodies and immune complexes.
- Associated with a plethora of clinical signs
- Always present in dogs which have a positive ANA test
- Usually treated initially with immunosuppressive doses of prednisolone
- Seldom cured and often requires lifelong maintenance therapy
Always present in dogs which have a positive ANA test
There are a number of vector-borne diseases that will result in a false positive ANA test
T/F: Azathioprine, Cyclosporin, and Mycophenolate mofetil are all recommended as single agent protocols in the treatment of IMHA
False
Mycophenolate mofetil can be used as a single agent protocol for treating IMHA
What is the cause for increased MCHC?
Artifact (in-vitro hemolysis)
The cause of death in cases of IMHA is usually:
thromboembolic disease
In your patients that are donating blood, they’ll ideally donate ~10% of their total blood volume. You never want to collect more than ____% of the total blood volume!
20%
If you collect >20% blood volume, the donor could go into hypovolemic shock
Between FDPs and D-dimers, which test is a more sensitive and more specific indicator for the development of thromboembolism?
D-dimers
- FDPs can occur without a clot, whereas we know that if we have D-dimers a clot has already formed*
- Although keep in mind that neither of these tests really has a good sensitivity*
If your patient has a platelet count <50,000/μL, increased megakaryopoeisis, and microthrombocytosis, these are hallmark findings for:
IMTP
Immune-mediated thrombocytopenia
What is the aim of glucocorticoid therapy in IMHA treatment?
reduce macrophage-mediate erythrophagocytosis and decrease immunoglobulin concentration
Can also alter generation and function of T lymphocytes
What is the main form of IMHA seen in dogs?
Primary IMHA
- Main form in dogs
- More prevalent in females
-
Breed predisposition
- American and other Cocker Spaniels
- Poodles, OES, Irish setters and Collies
- No age predisposition
This miniature schnauzer has a platelet count of 64,000/uL. What is the most likely etiology of the petechiation?
- Thrombocytopenia
- Thrombocytopathy
- Coagulopathy due to factor deficiency
- Fibrinolysis increased
Thrombocytopathy
-
Why not the other answers?
- Anything below 100,000/μL is thrombocytopenia, but it’s not likely the reason for the petechiation. You’re not going to bleed spontaneously if you have a platelet count that high.
- Not a factor deficiency - these are usually associated with body cavity bleeds, ecchymosis, hyphema, etc.
- We usually only see fibrinolysis post-operatively
In which canine breed do we most commonly see macrothrombocytopenia?
Cavalier King Charles Spaniel
They actually have a reduced number of platelets, but because their platelets are large they usually have a normal platelet volume
List the Vitamin K dependent coagulation factors:
II, VII, IX, X
What are some causes for an decreased MCV?
- Iron deficiency anaemia
- Japanese Akita dogs
- Anemia of chronic disease
- Portosystemic shunts
Which test of coagulation will be increased first in the case of Vitamin K antagonism or deficiency: PT or aPTT?
PT
- PT commonly* ↑ first & more marked than aPTT (factor VII has shortest t1/2) - 36 hr
- **Note: When available, PIVKA (patient-side test) can detect coumarin or warfarin toxicity as early as 12 hours after ingestion***
With mild/moderate thrombocytopenia, platelet count is greater than _________
50,000
With mild/moderate thrombocytopenia, platelet count is _> 50,000/uL_
-
Spontaneous bleeding evident
- DIC
- Thrombocytopathy
- 2˚ hemostasis disorder
-
No spontaneous bleeding evident
- Consumption-acute (check for internal bleeding)
- Early infectious disease
You note this abnormal monocyte in a dog. What is your diagnosis?
Ehrlichia canis
What are the four categories of thrombocytopenia?
- Failure of megakaryopoiesis (production)
- Increased consumption/demand
- Destruction
- Sequestration
What are the causes for decreased MCHC?
regeneration, chronic iron deficiency
A Border collie presents to your clinic due to inappetence and anorexia. You detect fever, with petechiation on the buccal m/m and ventrum. The most likely differential is:
- Rodenticide toxicity
- Thrombocytopathy
- Immune mediated thrombocytopenia
- Von Willebrand’s disease
Immune mediated thrombocytopenia
For blood collection, sodium citrate is used as an anticoagulant. The recommended ratio is ____ mL of blood for every ____ mL of anticoagulant
For blood collection, sodium citrate is used as an anticoagulant. The recommended ratio is 9 mL of blood for every 1 mL of anticoagulant
T/F: A direct Coomb’s test is used to distinguish primary from secondary IMHA
False
The direct Coombs test, or direct antiglobulin test (DAT), detects the presence of antibody and/or complement bound to patient RBC membranes. The test is used for diagnosis of IMHA, but a positive Coombs test does not distinguish primary from secondary IMHA
T/F: Acute and Chronic Ehrlichiosis are both known to cause bone marrow suppression
False
Chronic Ehrlichiosis causes bone marrow suppression. Acute Ehrlichiosis is responsible for IMTP, vasculitis, and peripheral destruction of platelets
T/F: Spherocytosis is a hallmark of immune-mediated disease in dogs
True
- Due to immune opsinisation of RBC and piecemeal removal of the membrane
- Smaller and darker staining
- Lose deformability
T/F: If you’re treating an IMHA patient with glucocorticoids and they’re showing no signs of improvement within the first two weeks, you should likely switch to another drug
False (or not necessarily)
There can be a delay of effect of up to 14 days with glucocorticoids. Persevere with the chosen therapy and do not switch drugs too hastily
What is the mainstay of treatment for immune-mediated thrombocytopenia (IMTP)?
immunosuppressants!
(prednisone + additional drug)
What is the characteristic RBC feature of IMHA on blood smear?
Spherocytosis
