Regenerative anaemias Flashcards

Question

Rouleaux

Answer 1

Appreciated visually as the cells clustering to look like a stack of coins. It is very common in normal cats and horses, and can be associated with hyperglobulinaemia. It can be differentiated from agglutination of cells by performing an in saline agglutination test (Rouleaux will disperse, agglutination will remain).

Answer 2

Imaging to look for neoplasia Rule out drug exposure from history PCR/serology for infectious agents - Babesia canis - Mycoplasma (cats) - FeLV (cats) Bone marrow examination - if anaemia is non-regenerative which could suggest precursor targeted immune mediated anaemia (PIMA)

Answer 3

Haemotropic mycoplasmas (cats Babesia (dogs, cattle) FeLV (cats) Leptospirosis (cattle, lambs, pigs) Clostridium (ruminants, horses) Equine infectious anaemia (horses)

Answer 4

AKA Feline infectious anaemia Mycoplasma haemofelis most pathogenic Transmission unknown - fleas, fighting? Attach to red cell membrane causing distorsion and extravascular haemolysis - some can cause antibody response leading to IMHA Cycline lasting 1-2d with 6d intervals, some become chronically infected carriers Can be seen in immune compromised dogs

Answer 5

Mycoplasmas can be seen on the blood smear but sensitivity is low Appear as small coccoid organisms on edge or within cells, sometimes forming chains - care not to confuse with stain precipitate PCR of blood most sensitive

Answer 6

Doxycycline Immunosuppression may be indicated in IMHA suspected

Answer 7

Intracellular protozoan parasites that are spread by the Dermacentor species of tick Usually only in dogs that have travelled but sporadic cases that have not Babesia can also affect cattle (red water fever) and it is spread between cattle by the Ixodes Ricinus tick. Can cause extravascular or intravascular haemolysis (+/- IMHA)

Answer 8

Can see on as paired intracytoplasmic organisms on blood smear (particularly red cells just below buffy coat) ○ More likely seen from capillary blood (e.g. ear prick) PCR – most sensitive Serology – shows exposure

Answer 9

Imidocarb diproprionate

Answer 10

Generally it is ok to transfuse a dog once without blood typing or cross matching (provided not given birth or been previously transfused). Many blood groups are described in dogs, but the most clinically relevant is DEA 1.1. Natural alloantibodies against DEA 1.1 are not present in dogs but are induced following transfusion or pregnancy/parturition. DEA 1.1 negative dogs will develop alloantibodies if transfused with DEA 1.1 positive blood and DEA 1.1 negative bitches that birth a DEA 1.1 positive pup will also develop anti-DEA 1.1 antibodies (if exposed to blood during parturition).

Answer 11

Must blood type +/- cross match before transfusion. Three blood groups are described; group A (most common in Domestic Short Haired cats), group B (more common in British shorthair, Birman, Devon Rex, Cornish Rex), and group AB (least common). Cats have naturally occurring alloantibodies: * A type cats have weak anti-B alloantibodies (-> minimal transfusion reaction). * B type cats have strong anti-A alloantibodies (-> strong transfusion reaction). * AB type cats have no naturally occurring alloantibodies

Answer 12

Horses have a complicated system of blood typing but groups Aa, Ac, Ca, Qa are the most clinically relevant. Horses that lack Aa, Ac, Ca antigens may have natural anti-Aa/Ac/Ca alloantibodies. In addition, Qa negative mares may develop anti Qa antibodies after birthing a Qa positive foal. Many thoroughbreds are Aa or Qa positive.

Answer 13

Occurs in type A kittens born to a type B mother. Anti-A antibodies will be present in colostrum and so will be absorbed into blood stream of kitten leading to haemolytic anaemia. These antibodies will cause intravascular haemolysis, severe anaemia, and sudden death. This can be avoided by blood typing mothers and toms to avoid a type A tom breeding with a type B queen. Otherwise type A kittens can be kept away from the type B mother for the first 48 hours after birth to avoid colostrum intake and allow gut closure to occur.

Answer 14

This will occur in Aa or Qa negative mares that acquires natural anti-Aa/Qa alloantibodies during previous foaling or transfusion and that give birth to a Aa/Qa positive foal.

Answer 15

Will see strong reaction if type A blood is given to a type B cat. Less severe reaction if type B blood given to type A cat, however blood typing or cross matching should be performed in all cases prior to transfusion.

Answer 16

No naturally occurring DEA 1.1. alloantibodies, so dogs can be transfused safely once, without cross matching/blood typing, provided they have not been transfused before, or been pregnant/given birth.

Answer 17

Oxygen within red cells is a potent oxidant which can cause formation of reactive oxygen species that can damage cells. Oxidant damage is limited by the presence of protective enzymes within red cells, however oxidative toxins can overwhelm action of protective enzymes leading to oxidative injury. Oxidation of red cells can cause damage in a number of ways: * Oxidation of globin chains leading to Heinz body formation * Cell membrane damage leading to eccentrocyte formation * Oxidation of Fe2+ in haem molecule to Fe3+ leading to methaemoglobin formation

Answer 18

These form due to oxidation of the SH groups in the globin chain. The Heinz body is precipitate of Hb attached to the inside of the red cell membrane. Affected cells are less deformable and so are phagocytosed in the spleen (extravascular haemolysis) or severely damaged cells are haemolysed in the circulation (intravascular haemolysis). Heinz body formation is more common in cats due to an increased number of SH groups (8 vs 4 in dogs). Heinz bodies can be seen on normal blood smears, where they appear as an unstained projection on the cell membrane, or can be seen more easily following staining of the cells with new methylene blue (Heinz bodies stain blue).

Answer 19

* Onion * Garlic (dogs) * Paracetamol (dogs and cats) * Zinc (dogs) * Red maple leaves (horses) * Kale and rape (ruminants)

Answer 20

Zinc and napthalene (moth balls) cause membrane damage and intravascular haemolysis with minimal or absent Heinz body / MetHb formation. Membrane damage results in formation of eccentrocytes – red cells in which haemoglobin is displaced to one side of the cell leaving a pale empty area on the other side. Again these are less deformable and so are removed by the spleen leading to extravascular haemolysis.

Answer 21

Fe2+ is oxidised to Fe3+, resulting in the formation of methaemoglobin (MetHb). Blood appears chocolate brown when 30 – 40% of total haemoglobin is in the form of methaemoglobin, and death occurs when it reaches 80 – 90%. You can test for MetHb by dropping venous blood onto white blotting paper. MetHb blood will remain brown, whereas normal blood will turn bright red (due to formation of oxyhaemoglobin).

Answer 22

Methaemoglobinaemia - causing choclate brown blood Cats are very sensitive to paracetamol because lack specific glucuronyl transferases required to conjugate aromatic compounds. Toxic dose usually 50 – 60 mg/kg, although fatal intoxication with total dose of 125 mg (1/4 tablet) has been reported. The toxic dose of paracetamol for dogs is much higher (150 – 200 mg/kg).

Answer 23

* Acute intravascular haemolysis -> haemoglobinuria (urine may be deep brown). * +/- Jaundice * Facial oedema * Salivation * Depression * Dilated unresponsive pupils * Vomiting * Tachycardia and moist rales * Seizures

Answer 24

N-acetylcysteine - this drug increases sulphate availability for conjugation of paracetamol and also provides cysteine for glutathione regeneration. Fluid therapy to avoid renal tubular damage due to haemoglobinaemia

Answer 25

Abnormal vessels e.g. vascular tumours/haemangiosarcoma Fibrin clots e.g. in disseminated intravascular coagulation (DIC) Valvular disease (endocarditis)

Answer 26

Acanthocytes - rounded, variable sized projections. Can be seen in normal dogs but also disorders causing fragmentation and liver disease Schistocytes - fragment sof RBCs, so should be smaller than single RBC Differentiate from crenated cells which are usually artefactual

Answer 27

Inherent metabolic defects - red cell enzyme deficiencies Leads to membrane damage and accelerated extravascular haemolysis and anaemia Red cell pyruvate kinase (PK) deficiency in Basenjis Red cell phophofructokinase (PFK) deficiencies in ESS, and Cockers.

Answer 28

Occurs in Basenjis as well as other breeds of dogs and some breeds of cats. Associated with a highly regenerative, severe anaemia, and often has a poor prognosis due to the development of myelofibrosis in middle age.

Answer 29

Reported in English Springer spaniels and Cocker spaniel. Mild or no anaemia, but haemolytic crisis may occur following exercise when hyperventilation leads to alkalemia. The red cells show a markedly alkaline fragility and so there is an increased rate of haemolysis during alkalemia.

Answer 30

Low phosphate availability leads to ATP depletion which in turn increases RBC membrane rigidity and decreases deformability of the cells, leading to intravascular haemolysis. This can occur in small animals following insulin therapy for diabetes mellitus (since insulin causes phosphate to move into cells) or can occur in post parturient hypophosphataemia in cattle (3-8 weeks post-partum).

Regenerative anaemias Flashcards

(54 cards)