32. Haemolytic anaemias in dogs and cats. Babesiosis

Question 1

Haemolytic anaemia

Answer 1

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

Question 2

Immune- mediated Haemolytic anaemia?

Answer 2

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

Question 3

Babesiosis?

Answer 3

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