32. Haemolytic anaemias in dogs and cats. Babesiosis Flashcards
Haemolytic anaemia
Haemolytic Anaemia
↓ In the number of circulating RBCs due to their destruction
Usually regenerative
CONGENITAL CAUSES
§ Pyruvate kinase deficiency (Basenji dogs; Beagles)
§ Phosphofructokinase deficiency (Spaniels)
ACQUIRED CAUSES
§ Chemicals § Drugs
§ IMHA* § Bacteria
§ Microangiopathic anaemia § Parasites
§ Rickettsia spp. § Venoms
*Immune-mediated haemolytic anaemia
CLINICAL SIGNS
§ Bilirubinuria § Fever
§ Splenomegaly § Lethargy
§ Hepatomegaly § Anaemia
§ Haemoglobinuria § Icterus
LAB. D
§ PCV: If the plasma is red after centrifuging, consider
haemolytic anaemia
§ Blood smear:
Cell morphology (Heinz bodies; Spherocytes)
Parasites
§ ↑ TP
§ Regenerative anaemia
Immune- mediated Haemolytic anaemia?
Immune-Mediated Haemolytic Anaemia
PATHOGENESIS
§ Complement/antibody-mediated RBC damage
§ Cytotoxic reaction (type-II hypersensitivity)
“True autoimmune haemolytic anaemia”
Altered RBC membrane → IgG & IgM are directed against these
RBC’s antigens → Outcomes are either:
§ Extravascular macrophage phagocytosis → Spherocytes
§ Intravascular cytolysis (complement system)
Classifications of IMHA
§ Idiopathic/primary
§ Secondary: Parasitic; Lupus; Drugs; Tumour; Immune
complex formation
Predisposed
Dogs > Cats; Collies; Rottweilers; Bobtail cats
Cases are seen seasonally due to parasite vector life-cycles
CLINICAL SIGNS
See under “General clinical signs of anaemia” & “Acute blood loss anaemia”
§ Cold agglutinin disease: Ear margin, toes & tail undergo
necrosis (areas where blood flows slowly) (see Fig. 32.1)
§ Evan’s syndrome: IMHA + Immune-Mediated
thrombocytopaenia → Petechiae; Epistaxis
Clinical signs associated with cold agglutinin disease. Necrosis of
the ear margin (a), nose (b), pads (c) and tail (d).
DIAGNOSIS
Microscopy of blood cells
§ Regenerative anaemia § Leucocytosis
§ Spherocytosis § Neutrophilia
§ Polychromasia § Anisocytosis
§ Autoagglutination § Left shift
Saline agglutination test
§ Assessment of IgM & IgG
§ If Ø Agglutination → Coomb’s test → Detects Ig &
complement on the RBC surface
Lab. D: ↑ Br; ↑ ALT
Osmotic fragility test
TREATMENT
Dexamethasone for the first few days → Prednisolone (3-5 weeks)
§ + Azathioprine (monitor BM suppression)
§ + Cyclosporine
Antibiotics
Heparin (to prevent against thromboembolism)
Blood transfusion
Babesiosis?
Babesiosis
Babesia canis, vogeli, rossi, gibsoni, microti et conradae
Transmitted by Dermacentor reticularis and other ticks
PATHOGENESIS
1-2 week incubation period
Invasion & replication of RBCs → Anaemia + associate signs →
Immune actions worsen the anaemia (Positive Coomb’s test)
Acute & chronic phases
May damage multiple organs by systemic inflammatory response
syndrome (SIRS)
CLINICAL SIGNS
See “Clinical signs”, under “Haemolytic anaemia”
Acute
§ Pale mucosa § Fever
§ Tachycardia § Anaemia
§ Tachypnoea § Anorexia
§ Splenomegaly § Weakness
§ Hepatomegaly § Depression
Chronic
§ Anaemia § Icterus
§ Weight loss § Anorexia
§ GI signs § Oedema
§ CNS signs § Ascites
DIAGNOSIS – LAB. D
History (travel to Mediterranean countries; tick prevention)
Blood smear → Giemsa staining
Serology; PCR
Other § Spherocytic regen. anaemia § Met. acidosis § Hyperbilirubinaemia § Azotaemia § Bilirubinuria § Proteinuria § Haemoglobinuria § Cylinduria § Polyclonal gammopathy § ↑ ALT § Dark brown urine § ↑ Creatinine § Thrombocytopenia § DIC § Leukopenia
Differential diagnosis: Immune-mediated haemolytic anaemia
Treatment
§ Imidocarb (IM) Antiprotozoal against Babesia spp. § Supportive care; Blood transfusion § Infusion therapy (to prevent kidney damage) § Diuretics: Mannitol; Furosemide (only if hospitalised) § Sodium bicarbonate therapy: Metabolic acidosis cases § Glucocorticoids (in IMHA cases) Prevention
§ Vaccine (though inefficient & temporary) § Imidocarb (monthly) § Tick prevention: Flumethrin collars