Blood Drugs, Pt. 3 Flashcards
What is fibrinolysis? How does this typically occur?
enzymatic breakdown of fibrin in blood clots to serve as a defense mechanism against overactivity of coagulation
tissue plasminogen activator and Factors XIa and XIIa activation plasminogen into plasmin that is able to breakdown fibrin into fibrin degradation products (FDPs)
What do fibrinolytic drugs do? When are they used in animals?
enhances the conversion of plasminogen to the active and fibrinolytic plasmin
not used often
- feline arterial thromboembolism
- canine pulmonary thromboembolism
What are the 2 main fibrinolytic drugs? How do they compare to heparins?
- streptokinase
- recombinant tissue plasminogen activator (rt-PA)
actively reduce the size of the clot
- heparins inhibit the growth
What is Streptokinase derived from? How is it used pharmacologically? Therapeutically?
β-hemolytic streptococci
PHARMACOLOGIC = plasminogen activator
THERAPEUTIC = thrombolytic medication and enzyme
What is the mechanism of action of Streptokinase? What are the 3 therapeutic effects?
combines with plasminogen to form activator complexes and converts into plasmin, which is able to degrade the clot-bound fibrin
- lysis of thrombi in coronary arteries in cats
- lysis of pulmonary emboli in dogs
- deep venous thrombosis in dogs
What are 4 common adverse effects of Streptokinase?
- systemic fibrinolysis
- coagulopathy
- serious hemorrhage
- metabolic acidosis, bleeding, death
How does recombinant tissue plasminogen activator (rt-PA) compare to Streptokinase? What pro does it have? What are 2 possible adverse effects?
single chain polypeptide serine protease with a higher affinity for fibrin within thrombi and a low affinity for plasminogen —> more local fibinolysis
less systemic bleeding problems
- serious bleeding
- potentially antigenic in animals due to it being a human protein
What do antifibrinolytic drugs do?
promotes hemostasis and decreases the need for RBC transfusion
What are the 2 most common antifibrinolytic drugs? What do they do? What are 2 possible adverse effects?
- Aminocaproic acid
- Tranexamic acid
synthetic lysine compounds that decrease fibrinolysis by binding to fibrin
- thrombosis formation
- neurologic evens (seizures)
What is anemia? What are 4 possible causes?
deficiency of healthy and regularly shaped RBCs
- lack of production of hemoglobin or RBCs due to bone marrow depression
- increased RBC destruction
- nutrient deficiency - iron, folic acid, vitamin B12
- excessive bleeding during surgery or trauma
What are the major causes of anemia in dogs?
- Cushing’s
- chronic diseases suppressing RBC production
- infectious disease
- intestinal bleeding
- medications that interfere with RBC production
- poisons or toxins
- cancer
- tick-borne disease
- poor nutrition
- hypothyroidism
- bone marrow disease
- kidney disease
- blood caused by parasited
What 4 dogs are at higher risk for developing anemia?
- Labrador retrievers
- American Cocker Spaniels
- Miniature Schnauzers
- Shih Tzus
What are the 4 major causes of anemia in cats?
- infection - FeLV, PIV, parasites (Mycoplasma hemophilus)
- blood loss from severe flea infestations in kittens
- immune-mediated disease
What are the 8 most common symptoms of anemia in dogs?
- pale gums, eyes, or ears
- weakness or lethargy
- black stools
- fast pulse and rapid breathing
- vomiting
- loss of appetite
- weight loss
- swelling of jaw or face
How is anemia typically treated?
- IV fluids
- deworming
- parasite medications
- GI medication
- chemotherapy
- surgery
- change in existing medications
- antibiotics
- immunosuppressive drugs
- bone marrow transfusion
- potassium phosphate supplements in cats
What is the difference between regenerative and immune-mediated hemolytic anemia?
REGENERATIVE = bone marrow is producing RBCs normally, but are losing blood due to bleeding disorders, accidents, injury, surgery, or internal bleeding from parasites, ulcers, or cancer
IMMUNE-MEDIATED = break down or destruction of RBCs due to genetic disease, autoimmunity, or conditions caused by toxins, parasites, or low phosphorus levels
What is non-regenerative or aplastic anemia?
deficiency of production of all blood cells
(aplastic = RBCs)
How can kidney disease cause non-regenerative anemia? What are some other causes?
lowers erythropoietin production, which is responsible for stimulating RBC production in bone marrow
- bone marrow disease
- chronic disease
- cancer (leukemia)
- toxins
- Parvovirus
- chemotherapeutic drugs
- nutritional deficiencies: iron, vitamin B, vitamin E, copper, phosphorus
How can iron deficiencies cause anemia? In which animals is this common?
hemoglobin is the red pigment protein on the RBC that uses 4 heme parts with iron to carry 4 molecules of oxygen
MOST COMMON in dogs and pigs
- less common in cats, horses, and ruminants
What is the main cause of iron deficiencies causing anemia?
RARELY NUTRITIONAL - most commonly secondary to chronic blood loss
What is sickle cell anemia?
hereditary genetic disorder that results in the production of abnormal/deformed hemoglobins (β subunit) that restrict their oxygen carrying capacity
What is vitamin B12? How does it interact with red blood cells? In what foods is it most commonly found in?
cobalamin - helps create the heme portion of hemoglobin, resulting in functional RBCs
red meat, dairy, eggs (NOT in plants)
What does a deficiency in vitamin B12 cause?
hematological and neurological symptoms
What is used for the prevention and treatment of iron deficiency anemia in animals?
FERDEX B12 - dextranic iron injectable
What is the most common autoimmune disease in dogs?
immune-mediated hemolytic anemia
- body attacks and destroys its own RBCs (hemolysis)
In what 4 ways is immune-mediated hemolytic anemia controlled?
- control the immune response (Azathioprine, Cyclophosphamide, Cyclosporine, Corticosteroids - Prednisone)
- blood transfusions
- supportive care - IV fluids
- supplementation with glycoprotein erythropoietin to stimulate RBC production
How is Azathioprine used to treat immune-mediated hemolytic anemia? What else can it be used to treat?
immunosuppressant that decreases metabolism of purines, which inhibits DNA/RNA sythesis
immune-mediated thrombocytopenia
What are 4 adverse effects of Azathioprine?
- bone marrow suppression leading to leukopenia and thrombocytopenia
- transient GI toxicity
- liver toxicity
- acute pancreatitis in dogs
How is Cyclophospamide used to treat immune-mediated hemolytic anemia?
potent immunosuppressant that has cytotoxic effects on B- and T-cells and has some antineoplastic and DNA-damaging abilities
What adverse effect is common in dogs taking Cyclophosphamide? How does this compare in cats?
sterile hemorrhagic cystitis
(+ bone marrow suppression leading to infection)
more resistant to the toxic effects on the bladder
How is Cyclosporine used to treat immune-mediated hemolytic anemia? What is its specificity?
potent immunosuppressant that inhibits T-cell receptor-activated signal transduction pathway by suppressing IL-2 to block the proliferation of T-lymphocytes
less specific to B-cells —> less myelosuppression or nonspecific reactions
What are 2 common erythropoietic-stimulating agents? What is their mechanism of action?
- Darbepoetic
- Epoetin alfa
stimulates erythropoiesis via the same mechanism as endogenous erythropoietin
What are the 2 most common usages of erythropoietin-stimulating agents?
- chemotherapy-induced anemia
- anemia due to chronic renal disease
In what species is non-regenerative anemia most common? Why?
cats - anemia of chronic disease
chronic kidney disease is very common in cats
What happens in cats with non-regenerative anemia (anemia of chronic disease)? How is this treated?
kidneys reelase less erythropoietin, leading to lowered RBC production by the bone marrow
Darbopoetin