Clinical Pathology

• Antibodies directed against RBC membrane antigens and Abcoated RBC’s are removed from circulation.
• Hemolytic process results in varying degrees of anemia depending on antibody type, speed of development, and duration of the disease process.
• Female dogs are more commonly affected than males.
• Certain breed predispositions include: Poodles,
Cocker Spaniels, Terriers, Old English Sheepdogs,
Lhasa Apsos, and Shih Tzus.
• Rare in cats, usually associated with FeLv or
Hemobartonella.

• The spleen is the primary site for removal of RBC’s coated with IgG while the liver removes RBC’s coated with IgM.
• Onset of anemia may be acute or gradual.
• Complications:
• DIC
• Pulmonary Thromboembolism

• Primary AIHA : autoantibodies directed against RBC’s with no underlying disorder, most common.
• May occur in association with immune mediated thrombocytopenia.
• Secondary AIHA : Ab production initiated by drugs, vaccines, infectious diseases and neoplastic disorders.

• History and Physical Exam
• CBC
• Regeneration
• Spherocytes
• Autoagglutination
• Anemia (PCV<20%)
• Coombs Test
• Splenomegaly and Hepatomegaly seen on radiographs.

• Corticosteriods:
• Reduces clearance of Ab coated RBC’s by inhibiting function of macrophages in the spleen and liver.
• Prednisone at dose of 2 mg/kg/day divided
BID.
• Blood transfusions in life-threatening situations.
• Other immunosuppressive drugs
• Cyclophosamide
• Azathioprine
• Cyclosporine
• Splenectomy
• Indicated if anemia is nonresponsive to immunosuppressive drugs.

• Primary failure of erythropoiesis
• Secondary failure of erythropoiesis
• Nuclear maturation defects
• Hemoglobin synthesis defects
• Aplastic anemia
• Marrow infiltration

• Patient stops producing red blood cells
• Circulating blood has few reticulocytes, normocytic, normochromatic RBC’s.
• Bone marrow normal except for hypoplasia of erythroblasts.
• May be immune-related or caused by certain drugs or neoplasia.

• Caused by a chronic disorder such as renal failure, liver disease, inflammatory disease, neoplasia, and endocrine disorders.
• Bone marrow is normal or has slight erythroid hypoplasia.

• Associated with folate and B
12
(rare).
deficiency
• Macrocytic, normochromic anemia due to a defect in DNA synthesis.
• Megablastic erythroblasts in bone marrow.
• Check serum folate and supplementation is the cure.

• Primary associated with iron deficiency.
• Microcytic, hypochromic anemia due to decrease Hb production in individual cells.
• Iron deficiency can result from a poor diet, poor absorption, and following an incident of marked blood loss.

• Bone marrow failure due to marrow necrosis and/or inflammation.
• Bone marrow is acellular or hypocellular resulting in anemia, thrombocytopenia, and leukopenia.
• Causes:
• Ehrlichia canis
• FeLv
• Parvovirus
• Estrogen
• Phenylbutazone
• Radiation
• Chemotherapy

• Neoplasia : crowding of marrow elements with neoplastic cells.
• Myelofibrosis : hypoplasia of marrow elements with replacement by collagen
(sequel to damaged marrow).
• Osteopetrosis : inherited disorder with increased bone density.

• Platelets are produced by fragmentation of megakaryocytes in bone marrow
• 150-200 platelets are formed from one megakaryocyte.
• Lifespan: 7-10 days
• Normal count: 200,000 – 500,000/mm 3
• Thrombocytopenia - most common cause of bleeding in dogs.
• Normal hemostatis depends on adequate platelet number and function
• Important role in primary hemostatis involving interaction between injured blood vessel wall and platelets

• Make sure you had a good stick, if not recollect sample from a large peripheral vein.
• If yes, perform coagulation test, CBC, tick panel.
• If those are normal, then check bone marrow

• Most common in middle-aged female dogs, less common in cats.
• May be primary cause similar to AIHA.
• Secondary causes are drugs, viruses, immune complexed, infectious disease, etc.

• Test platelets
• Platelet count
• Bleeding time
• Test Coagulation Factors
• Activated Clotting Time (ACT)
• Activated Partial Thromboplastin Time
(PTT)
• Prothrombin Time (PT)

• Von Willebrand disease (vWD): factor VIII decreased.
• An additional portion of the molecule which is important in platelet function is decreased or absent.
• Abnormal platelet function.
• Increased mucosal surface bleeding time.
• Excessive surgical bleeding.
• Chronic, low grade bleeding possible.
• PTT may be mildly prolonged
• Antigen test

• Normal clotting time 2-4 minutes
• Platelet dysfunction at 10-12 minutes
• Begin timing immediately after making cut.
Wound should not be wiped or disturbed until it has clotted.

• Normal time is 2-8 minutes
• Begin timing at the time the nail is cut.
Discrete drops of blood should fall from wound. A steady stream indicates that the wound is too far in the cuticle.

• Contagious and potentially fatal viral disease in horses.
• No vaccine or treatment exists.
• Transmitted by biting insects such as horseflies and deerflies.
• Can also be transmitted by dirty needles.
• Also called Swamp Fever
• Two stages :
• Acute
• Develops severe, acute signs within 2-3 weeks. Signs occur rapidly and cause only a slight increase in temperature, 30% of horses die at this stage
• Chronic
• Temperature > 105˚ F

• Petechial hemorrhage
• Depression
• Weight loss
• Edema in legs and abdomen
• Anemia

• Checks for antibodies to the virus
• Positive Test Options
• 1. Retest
• 2. Euthanize
• 3. Sale for immediate slaughter
• 4. Lifetime Quarantine

• Retest in 30 days at TVMDL
• Official reactors are permanently marked by using a National Uniforms Code branded on the left shoulder or neck.
• Quarantine should be at least 200 years from other equine
• All exposed equines must be tested

• Ehrlichia platys
• Brown dog tick transmits
• Erhlichia canis
• Common in TX
• Transmitted by Brown dog tick
• 3 stages of disease
• (acute, subclinical, and chronic)
• Hemobartonella felis
• FIA (feline infectious anemia)
• Rickettsial organism
• Transmitted by fleas, ticks, blood transfusions, queen to kitten.
• Hemobartonella canis
• Rarely seen in dogs
• Cytauxzoon felis
• Fatal disease characterized by anemia
• Thought to be transmitted by ticks
• Anaplasma marginale
• Rickettsial organism
• Transmitted mechanically through equipment
• Babesia bigemina
• Reportable in cattle
• Texas fever, Redwater fever, Cattle tick fever
• Babesia canis
• Babesia Gibsoni