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InFocus

Surgical spontaneous haemoabdomen in dogs and splenectomy

Diagnostic testing as well as stabilisation and timing of surgery should be carefully considered before diagnosing and treating spontaneous haemoabdomens caused by splenic bleeding

Trauma is an uncommon cause of intra-abdominal haemorrhage in dogs and this article will focus on spontaneous haemoabdomens, particularly those resulting from splenic bleeding. Causes of generalised coagulopathy should be considered, particularly in young animals or when there are clinical signs suggesting multifocal bleeding or bruising.

FIGURE (1) Approximately 60 percent of haemoabdomens originate from the spleen. Shown here is a spleen affected by multiple nodules

Approximately 60 percent of haemoabdomens originate from the spleen (Figure 1). Incidentally diagnosed mass lesions have an approximate ratio of 50:50 benign to malignant, and spontaneous haemorrhage is associated with a higher risk of malignancy (around 85 percent). Splenic haemangiosarcoma (HSA), which accounts for 67.5 percent of splenic malignancies in large breed dogs and 50 percent in small breed dogs (Fleming et al., 2018), carries the most guarded prognosis of the malignancies. If there are no identified metastases, it has a median survival time (MST) of 1.8 months with surgery only, extended to 3.4 months with adjunctive chemotherapy. In the presence of metastases, MST is 0.9 months with no dogs surviving to one year (Wendelburg et al., 2015).

A recently proposed haemangiosarcoma likelihood prediction system (HeLP score) uses body weight, total protein, platelet count and thoracic radiographs to categorise the risk as low, moderate and high (Schick et al., 2019). This could help provide semi-objective prognostic information to help owners when making challenging decisions. Prognosis for splenic malignancies other than HSA varies on histopathological diagnosis; for most benign lesions, prognosis following surgery is excellent.

FIGURE (2) A right adrenal mass with haemorrhage from the cranial pole. A tourniquet has been pre-placed around the caudal vena cava

Hepatic bleeding accounts for around 15 percent of haemoabdomen in dogs with an increased incidence (27 percent) in dogs weighing less than 20kg. While uncommon, haemorrhage from other intra-abdominal organs, such as the kidney, adrenal gland (Figure 2) and omentum, should be preoperatively considered. Adrenal bleeding might be more commonly retroperitoneal and present as a dorsal abdominal mass lesion.

Clinical presentation

Ataxia, collapse, exercise intolerance, tachypnoea and lethargy are relatively non-specific clinical signs that can lead to misdiagnosis of neurological, cardiac or respiratory disease. Provide immediate oxygen supplementation (eg flow-by or face mask) and place an intravenous catheter during the initial clinical examination in a collapsed animal. Early analgesia, generally an opioid agonist, is necessary. Unless contraindicated by cardiac or renal disease, early intravenous fluid provision is a priority.

Pale mucous membranes, prolonged capillary refill time, tachycardia, weak peripheral pulses and collapse are consistent with hypovolaemic shock and repeated comparison with presenting values helps monitor response to treatment.

Abdominal distension and fluid thrill can be subtle, particularly in obese dogs. A relatively small volume of circulatory blood loss can cause a clinically significant hypovolaemia depending on the original volume status or the animal’s physiological ability to compensate. Abdominal fluid should not be assumed to be blood even if the animal’s clinical signs and signalment raises the index of suspicion.

Diagnostic testing

Point-of-care ultrasound (POCUS) of the abdomen is quick and inexpensive, with a large volume of free fluid easily recognised. Small volume recognition can be challenging; evaluation for hypoechoic pockets in gravity dependent regions, particularly between liver lobes and around the bladder neck, can improve identification. Visualising an intra-abdominal mass can be helpful at this stage, but identifying the underlying cause is not necessarily the purpose of POCUS and the priority is stabilising the dog.

Abdominocentesis is essential to identify the ascitic fluid. Blind four-quadrant abdominocentesis is feasible but aspiration of blood from an organ or vessel, or missing smaller volume haemorrhage, could be misleading. If the sample does not clot, it likely represents haemoabdomen.

PCV/TS of effusion higher than circulatingOld haemorrhage
Circulating volume re-expansion
PCV/TS of effusion much lower than circulatingUnlikely to be simple haemorrhage (eg blood contamination, blood with a different fluid)
PCV/TS of effusion same as circulatingAcute haemorrhage
TABLE (1) A comparison between the packed cell volume (PCV) and total solids (TS) of effusion and circulating blood

The packed cell volume (PCV) and total solids (TS) are compared against circulating values (Table 1). Fluid appearance is not accurate to identify simple haemorrhage as blood contamination of ascites can result in a rich red colour despite a relatively low red blood cell count. For example, a traumatic uroabdomen may look like blood but only have a PCV of 5 to 10 percent versus a circulatory PCV of 35 to 55 percent. Neoplastic cells are occasionally identified by cytology with low sensitivity. A normal circulatory PCV is common during acute bleeding and can be deceptive (Table 2).

Timing of bleedingPCVTSReason
Peracute bleedingNormalNormalRed blood cells (RBC) and plasma are lost in the same proportion
Subacute bleedingNormalReducedSplenic contraction releases RBC into the circulation. Water drawn from the extracellular space to maintain volume of the intravascular compartment dilutes proteins
Progression of bleedingReducedReduced or stablePersistent loss of RBC beyond compensation
TABLE (2) The time of bleeding and associated changes in the packed cell volume (PCV) and total solids (TS)

Stabilisation and timing of surgery

Haemorrhage reduces circulatory total oxygen carrying capacity from corpuscle loss and cardiac output due to intravascular volume loss impairing oxygen delivery to the brain. Provision of whole blood manages these problems and is the mainstay of treatment in human medicine, but this resource is limited in veterinary medicine. Blood transfusion in an actively bleeding animal may result in immediate loss into the abdomen and the timing of provision deserves careful consideration. 

Serial measurement of blood pressure, heart rate and pulse quality are fundamentally important in monitoring the animal’s response to intravenous fluid boluses, and guide additional treatment, such as repeat bolus, ongoing fluid therapy or requirement for vasopressors, and the urgency of surgical intervention. Endpoints for emergency resuscitation can include a mean arterial pressure greater than 60 to 70mmHg with a complementary decrease in heart rate (ideally below 120 in a relaxed dog) and improvements in peripheral pulse quality.

Serial measurement of blood pressure, heart rate and pulse quality are fundamentally important in monitoring the animal’s response to intravenous fluid boluses

A full description to manage critical hypovolaemia is beyond the scope of this article, but options include:

  • Isotonic crystalloid: 10 to 20ml/kg over 15 minutes, then reassess. To be repeated two to three times
  • Hypertonic crystalloid: 2 to 4ml/kg over 15 minutes. A rehydrating crystalloid supplementation will also be necessary
  • Autologous blood transfusion (ABT): artificial or natural colloids (eg whole blood, fresh frozen plasma and packed red blood cells) remain in the intravascular compartment for longer. ABT can be performed by aseptically collecting abdominal blood and returning it to the circulation via a blood filter either during stabilisation or during surgery (Higgs et al., 2015). Haematogenous seeding of neoplastic cells into the circulation is possible but, particularly with HSA, metastasis may have already occurred, therefore ABT should be pragmatically considered if it is life-saving in the short term

If repeated fluid boluses and vasopressors fail to normalise cardiovascular parameters (particularly the blood pressure), surgical intervention in the unstable patient may be required if the rate of haemorrhage is consistently exceeding volume replacement.

Owners must have a realistic expectation of the possible causes and prognoses; inflated three-view thoracic radiographs for gross metastasis can help in the owners’ decision on whether to operate or perform euthanasia. Pragmatic exploratory coeliotomy is reasonable without further investigations if the owners simply wish to deal with the current emergency and are warned about prognoses (recorded in the clinical notes).

Splenectomy

Improved exposure of the abdominal cavity (Figure 3) is achieved by:

  • A long midline coeliotomy. This is generally from xyphoid to caudal to the umbilicus but with the animal clipped and prepared so that this can be extended to the pubis if required to improve access and exteriorisation of large masses (Figure 4)
  • Surgical suction to remove blood and lavage (Figure 5). On abdominal entry, blood can be aseptically collected into 50ml syringes for ABT as required
  • Excision of the falciform fat with any small associated vessels cauterised or ligated
  • Using self-retaining abdominal retractors such as Balfour (Figure 3) or Gosset

Omental adhesions should not be peeled away; instead the omentum should be transected to minimise haemorrhage and residual gross neoplasia. In cases of problematic splenic masses, the authors have cross-clamped the spleen with Doyen bowel clamps and performed rapid partial splenectomy of the mass to improve visualisation and limit bleeding before proceeding with a standard splenectomy. The spleen should be submitted for histopathology.

Techniques for splenectomy include:

  • Hilar ligation (Figure 6): vessels are double ligated close to the spleen. This technique is safe but can be time-consuming
  • Vessel sealing device: energy instruments can rapidly cauterise and sometimes transect vessels along the splenic hilus (Rivier and Monnet, 2011). In hospitals with such devices, this has become the standard method to minimise patient morbidity, surgical time and cost
  • Non-hilar ligation: the splenic artery is identified within the omental bursa and branches to the left pancreatic limb are visualised. For this procedure, double ligation of the splenic artery and vein distal to the pancreatic branches (Figure 7), the left gastroepiploic artery and vein, short gastric arteries (Figure 8) and the omentum to the tail of the spleen requires fewer ligatures than hilar splenectomy

Immediate triage, rapid diagnosis by abdominocentesis and appropriate volume resuscitation with regular monitoring of cardiovascular parameters are essential in minimising morbidity and mortality.

Splenectomy is the most common procedure to manage haemoabdomen but hepatic bleeding could require liver lobectomy in up to 25 percent of small-breed dogs. Surgery is performed either once the dog is stable, which can be up to 12 to 24 hours later if they are monitored regularly and consistently have normal BP/HR, or as an emergency if stabilisation is not possible due to ongoing haemorrhage.

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