9. Oncological emergencies

Oncological emergencies can be divided into two major categories – tumour related and treatment related.



Tumour-related emergencies (Table 9.1)


Tumour-related emergencies could be due to the primary effect of the tumour on the patient, e.g. a dog with a ruptured splenic mass, or the secondary effects caused by a paraneoplastic syndrome (PNS), e.g. severe hypoglycaemia secondary to an insulinoma. For a more detailed discussion of PNS and tumour-related emergencies, see Chapter 10.





































































Table 9.1 Tumour-related oncological emergencies
PTH, parathormone; PTHrP, parathormone-related peptide.
Problem Cause Tumour Treatment
Anaemia Blood loss Bleeding tumour – haemoabdomen Blood transfusion
Immunity mediated Lymphoma, leukaemia Steroids ± blood transfusion
Hyperviscosity Paraproteins Myeloma, lymphoma Fluids, cytoreductive
chemotherapy
Hypercellularity Leukaemia Fluids, cytoreductive chemotherapy
Polycythaemia Renal carcinoma or metastasis to kidney Fluids, phlebotomy
Disseminated intravascular coagulation Disruption to normal clotting process Haemangiosarcoma, inflammatory carcinoma Treat underlying tumour, plasma transfusion
Hypoglycaemia Hyperinsulinaemia
Insulin-like growth factor II
Insulinoma, sarcomas, hepatic neoplasia I.v. dextrose
Hypercalcaemia Increased PTH
Increased PTHrP
Parathyroid tumour/hyperplasia
Carcinomas, lymphomas, sarcomas
Aggressive saline diuresis; furosemide if hydrated, steroids if confirmed lymphoid origin
Effusions Metastatic cancer
Thoracic duct obstruction
Carcinomas, haemangiosarcomas, lymphomas, etc. Thoracocentesis, pericardial tap, etc. treat underlying cause
Fever Inflammation
Infection
Lymphoma, leukaemia Fluids, antibiotics, anti-inflammatories
Seizures Primary brain tumour, hypoglycaemia, hyperviscosity Glioma, meningioma, insulinoma, myeloma, etc. Stabilize seizures depending on underlying cause
Urinary blockage Tumour extension into urethra Sarcoma, carcinoma Place urinary catheter

The goal of this section is to outline how patients with underlying neoplastic conditions may present in the emergency situation, but the reader is reminded that for each category there are many non-neoplastic conditions with similar presentations, so full evaluation and assessment of the patient are essential. Also, the reader is directed to individual chapters for more detailed discussion of each tumour type.


Anaemia


Unless the anaemia has resulted from acute blood loss it is rarely an emergency, even though it is a common sequela not only of neoplasia but also of long-term chemotherapy. The various causes of anaemia are discussed in Chapter 10.

Transfusions should be considered in oncological cases when the patient is clinical for the anaemia or when the packed cell volume (PCV) is falling rapidly. A cat with a PCV of 15 that is not weak, tachycardic or very lethargic does not need to be transfused as an emergency. However, this patient does require close monitoring as the situation could change depending on the underlying cause of the anaemia. If the same cat had a PCV <10%, then a blood transfusion is necessary because the oxygen-carrying capacity of the blood is reduced and cardiovascular collapse can occur.

Depending on the cause of anaemia a number of blood components are available for transfusion; however, whenever possible, component therapy rather than whole blood transfusions are indicated (Feldman 2000; see Table 9.2).





































Table 9.2 Indications for blood products in canine patients
HBOC, haemoglobin-based oxygen carrier.
Condition Component of choice 1st alternative 2nd alternative
Blood loss anaemia (hypovolaemic) Packed red blood cells and crystalloid or colloid fluids HBOC Whole blood
Blood loss (normovolaemic) Packed red blood cells HBOC Whole blood
Anaemia secondary to bone marrow failure Packed red blood cells Whole blood HBOC
Haemolytic anaemia Packed red blood cells HBOC Whole blood
Disseminated intravascular coagulation Fresh frozen plasma


Dogs


The DEA blood groups in dogs are well established and currently blood typing cards are available to check the DEA1.1 antigen (the most immunogenic) before a transfusion (Giger 2000). Both the donor and recipient should be typed. The best donors are DEA1.1 negative. DEA1.1 positive blood should only be given to DEA1.1 positive recipients because of the potential of inducing anti-DEA1.1 antibodies in negative dogs transfused with positive blood (Giger et al 1995). The recent report of a new blood type antigen, Dal, identified initially in Dalmatians, may mean that screening against more than DEA1.1 will be necessary (Blais et al 2007). If multiple transfusions are to be given to a particular patient over a period of days it is necessary to crossmatch all future blood after 4 days to prevent a transfusion reaction.

Accurate records of what has been given to a patient should be recorded on their file. For any anaemic patient the best transfusion product is packed red blood cells as less ‘foreign’ protein is transfused and there is therefore a reduced likelihood of an adverse immune response to minor histocompatibility antigens. Giving the correct blood component rather than whole blood also reduces the potential for fluid overload in normovolaemic patients.


Cats


The AB blood group system is recognized and consists of three types: A, B and AB. In cats the presence of naturally occurring alloantibodies means that giving the wrong blood type to a patient can result in fatal transfusion reactions, even with a first transfusion. Ideally, a crossmatch should be done prior to any blood transfusion (Giger 2000). The typing cards commercially available can distinguish the two major blood groups recognized in cats, A and B. However, in the rare case of a suspected AB cat, the blood should be sent to an outside laboratory for typing. The prevalence of blood types varies geographically and within breeds (Giger et al 1989, Knottenbelt et al 1999).

Breeds with a high incidence of B blood type include British Shorthair (40%) and Cornish/Devon Rex (30%); breeds with no reported B blood type include Siamese and Tonkinese. Weinstein has recently reported on the presence of an additional red cell antigen, Mik (Weinstein et al 2007). In cats, blood components are not as readily available as in dogs so whole blood transfusions are usually given. Finding a B donor cat can be very difficult and in such instances haemoglobin-based oxygen carrier (HBOC) products are available (Muir & Wellman 2003).

When giving a blood transfusion, the volume to be transfused can be calculated as follows:


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where k = 90 for dogs and 60 for cats.



Hyperviscosity/polycythaemia


Sep 11, 2016 | Posted by in SMALL ANIMAL | Comments Off on 9. Oncological emergencies
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