Lecture 28 (Disorders of primary haemostasis)

What does the term "haemorrhage by rhexis" mean?

What does the term "haemorrhage by diapedesis" mean?

[blank_start]haemothorax[blank_end] = haemorrhage into the pleural cavity [blank_start]haemopericardium[blank_end] = haemorrhage into the pericardial sac [blank_start]haemoperitoneum[blank_end] (haemabdomen or haemoabdomen) = haemorrhage into the peritoneal cavity [blank_start]haemarthrosis[blank_end] = haemorrhage into a synovial joint [blank_start]haematuria[blank_end] = haemorrhage into urine [blank_start]haemoptysis[blank_end] = coughing of blood [blank_start]haematemesis[blank_end] = vomiting of blood [blank_start]haematochezia[blank_end] = passage of fresh blood in faeces (typically over the surface of stools) [blank_start]dysentery[blank_end] = diarrhoea containing blood [blank_start]melaena[blank_end] = diffuse, dark red-black discolouration of faeces due to upper alimentary tract haemorrhage or swallowing of blood from the respiratory tract [blank_start]epistaxis[blank_end] = bleeding from the nose [blank_start]hyphaema[blank_end] = haemorrhage into the anterior chamber of the eye

[blank_start]petechiae[blank_end] = tiny, pinpoint foci of haemorrhage, 1-2 mm in diameter, typically found in skin and on mucosal and serosal membranes [blank_start]purpura[blank_end] = slightly larger haemorrhages ≥ 3 mm in diameter [blank_start]ecchymoses[blank_end] = larger foci of haemorrhage, 2-3 cm in diameter; usually blotchy and of irregular shape [blank_start]paintbrush (or suffuse or suffusive)[blank_end] haemorrhages = linear or streaky haemorrhages, especially over serosal or mucosal membranes, as if a brush dipped in red paint has been hastily splashed across the tissues [blank_start]haematoma[blank_end] = a palpable, discrete, space-occupying mass of clotted blood within tissues, small "" are common at sites of difficult venipuncture

The gross colour of haemorrhage depends on whether the blood was arterial or venous, the volume of extravasated blood and the time elapsed since haemorrhage occurred. What colour does the bruise appear during the acute, sub-acute and chronic stages and what is the molecule causing this colouration? In the acute phase, bruises appear [blank_start]red-blue[blank_end] due to the presence of poorly oxygenated [blank_start]haemoglobin[blank_end] In the subacute phase, bruises appear [blank_start]blue-green[blank_end] due to the formation within macrophages of [blank_start]biliverdin and bilirubin[blank_end] (derived from the porphyrin component of haemoglobin) In the chronic phase, bruises appear [blank_start]gold-brown[blank_end] due to the formation of [blank_start]haemosiderin[blank_end] and, to a lesser extent, haematoidin +/- lipofuscin pigments

What happens to a haematoma from 5-7 days after onset?

[blank_start]haemosiderin[blank_end] (composed of ferritin micelles (iron + apoferritin) derived from the iron component of haemoglobin) first appears microscopically within macrophages by 24-48 hours after the onset of haemorrhage. Sufficient "" accumulation to cause gross yellow discolouration is not expected until 2-3 days after haemorrhage. [blank_start]Haematoidin[blank_end] is a bright golden extracellular pigment composed of precipitates of bilirubin complexed with tissue proteins [blank_start]Lipofuscin[blank_end] is an intracellular yellow-brown pigment derived from peroxidation of phospholipids of membranes of damaged cells in the area

What factor(s) determine the clinical significance of haemorrhage? (select the answer or answers that are correct)

[blank_start]internal haemorrhage[blank_end] (haemorrhage into tissues or body cavities) --> reutilisation of plasma proteins and iron [blank_start]external haemorrhage[blank_end] (e.g. from the skin or gastrointestinal, respiratory, urinary or reproductive tracts) --> if recurrent or prolonged= hypoproteinaemia and iron deficiency anaemia

What is the most common cause of haemorrhage in domestic animals?

What is the clinical sign this horse is exhibiting?

What is the correct terminology for each of these poo/faeces samples?

What is the correct terminology for each of these forms of haemorrhage?

How would you correctly describe each of these haemorrhagic lesions?

Below are two lists of possible "features" or "symptoms relating to primary or secondary haemostasis, which list belongs to primary haemostasis and which to secondary haemostasis? [blank_start]Secondary haemostasis[blank_end] •delayed bleeding after venipuncture •large volume bleeds •petechiae rare •haematomas common •bleeding into muscles, joints and/or body cavities •bleeding may be localised •+/- mucosal bleeding [blank_start]Primary Haemostasis[blank_end] •bleeding immediately after venipuncture •small volume bleeds •petechiae common •haematomas uncommon •bleeding from mucous membranes •bleeding from multiple sites

Disseminated intravascular coagulation (DIC) is a combined disorder of both Primary and Secondary Haemostasis.

Match the below words with the correct definition [blank_start]Thrombocytopenia[blank_end]- deficiency of platelets in the blood. Can result in bleeding into the tissues, bruising, and slow blood clotting after injury. [blank_start]Haemorrhagic diatheses[blank_end]- clinical disorders of haemostasis characterised by a bleeding tendency [blank_start]Myelophthisis[blank_end] - replacement of haemopoietic bone marrow by neoplastic tissue (e.g. leukaemia), collagen (myelofibrosis), bone (osteosclerosis) or inflammatory exudate (e.g. chronic granulomatous osteomyelitis in systemic fungal infections) [blank_start]Thrombocytopathy[blank_end]- platelet dysfunction

Which of the below are disorders of Primary Haemostasis?

Which of the below are disorders of Secondary Haemostasis?

Disorders of secondary haemostasis provoke multiple short-lived bleeds that cease once the coagulation cascade generates fibrin

What is the most common acquired haemostatic disorder in dogs and cats?

What is the MOST COMMON mechanism responsible for clinically significant thrombocytopenia in cats?

What is/are the most common mechanisms of decreased platelet production in cats that lead to thrombocytopenia?

Of the below which can cause marrow aplasia or panhypoplasia?

Which is the correct order of cell lifespan (from longest to shortest)?

What is the most common mechanism of thrombocytopenia in dogs?

What is the most common cause of platelet destruction in dogs?

Platelet consumption due to formation of numerous microthrombi is typical of disseminated intravascular coagulation (DIC)

In health what percentage of platelets are located in the spleen?

In most circumstances, does sequestration of platelets cause a mild, moderate or severe thrombocytopenia?

Why does massive acute haemorrhage usually only cause a mild subclinical thrombocytopenia?

Define Thrombopathia

Which is the most common inherited bleeding disorder of dogs?

What is the role of the large glycoprotein von Willebrand factor?

Where can von Willebrand's factor expressed and/or stored?

Determine which is type 1, type 2 and type 3 von Willebrand's disease forms from the below lists of information [blank_start]Type 1 vWD[blank_end] - the most common form of vWD in dogs (> 90% of cases) - all of the various multimer chains of vWf are present but in reduced plasma concentrations (< 50% of normal) - e.g. doberman pinscher (in the not so distant past, approximately 60% of dobermans in Australia were thought to be carriers of the trait), Welsh corgis, German shepherd dogs, golden retrievers, and poodles - may be subclinical or cause mild to moderate bleeding - bleeding does not usually occur until the plasma vWf concentration falls below 20% of normal [blank_start]Type 3 vWD[blank_end] - there is virtually negligible vWf in plasma, with all multimers absent - Scottish terriers (the main breed affected in Australia), Shetland sheepdogs, Chesapeake Bay retrievers and Dutch kooikers - trauma in homozygotes --> severe haemorrhage [blank_start]Type 2 vWD[blank_end] - decreased plasma vWf concentration is associated with a disproportionate loss of the large high m.w. multimers - can be responsible for severe haemorrhage - rare but reported in German short-haired and wire-haired pointers - also reported in horses

Dogs with vWD will often bleed spontaneously