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Diagnosis and treatment of a suspected pseudoaneurysm of the femoral artery in a working police dog a
A Tikekar & HR Milner
a
a
Vetspecs 90 Disraeli Street Addington Christchurch 8024 New Zealand Accepted author version posted online: 09 Sep 2014.Published online: 05 Feb 2015.
Click for updates To cite this article: A Tikekar & HR Milner (2015) Diagnosis and treatment of a suspected pseudoaneurysm of the femoral artery in a working police dog, New Zealand Veterinary Journal, 63:2, 121-124, DOI: 10.1080/00480169.2014.961991 To link to this article: http://dx.doi.org/10.1080/00480169.2014.961991
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
New Zealand Veterinary Journal 63(2), 121–124, 2015
121
Peer-reviewed Correspondence
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Diagnosis and treatment of a suspected pseudoaneurysm of the femoral artery in a working police dog
An aneurysm is a localised saccular or fusiform dilation of the arterial wall and arises from weakening in the tunica media of the arterial wall, with intact but stretched tunica intima and adventitia. Pseudoaneurysms are localised haematomas with a persistent communication with the native artery or vein via a narrow neck. These lesions lack a fibrous wall and are contained by a surrounding shell of haematoma and the overlying soft tissues. Pseudoaneurysms are caused by rupture of a true aneurysm or by direct trauma to the artery. True aneurysms are differentiated from pseudoaneurysms only by histology (Williams et al. 1993). However, detection of a neck connecting a pseudoaneurysm with the injured artery using colour Doppler ultrasonography, and identification of turbulent blood flow within this neck is considered to be a hallmark of a pseudoaneurysm. The positive diagnostic rate of colour Doppler ultrasonography is reported to be about 95% in the human literature (Demirbas et al. 2005). Colour Doppler ultrasound examination is considered to be a sufficient and effective tool for the diagnosis of pseudoaneurysms. In humans, most peripheral pseudoaneurysms are iatrogenic following interventional catheterisation procedures or, less commonly, are post-traumatic (Lenartova and Tak 2003). Venous pseudoaneurysms have a low incidence of clinical sequelae but arterial pseudoaneurysms have unpredictable behaviour and their morbidities in humans include expansion, rupture, arterial thrombosis and distal embolisation (Kang et al. 2000). Diagnosis of an arterial pseudoaneurysm is best made on clinical findings and by colour duplex ultrasonography. There may be a pulsatile palpable mass that demonstrates a ‘yin/yang’ or a ‘to and fro’ pattern on colour flow Doppler or Doppler waveform analysis, respectively (Polak 1995). We report here a case of a post-traumatic femoral arterial pseudoaneurysm in a dog complicated by femoral compartment syndrome. Compartment syndrome is defined as a dysfunction of organs or tissues within a compartment that develops secondary to increased pressures within that compartment. Inelastic tissue such as fascia and bone can form a compartment in the extremities. Four such osteofascial compartments have previously been described in dogs (Basinger et al. 1987).
the first 4 days following this incident weight bearing was good on the affected limb. Subsequently distal limb oedema developed, with pyrexia and decreased weight bearing. Foreign body cellulitis from a putative stick penetration was suspected. Clinical signs of limb swelling, pyrexia and limb disuse worsened over the following week despite the use of antibiotics, diuretics and non-steroidal anti-inflammatory drugs. Specialist referral for further evaluation was then sought. On presentation the dog was pyrexic (temperature 39.4°C) and the left thigh was swollen to approximately twice the contralateral hindlimb. The limb felt firm and was painful on palpation. Oedema was present from the left stifle distally to the digits. The paw was warm to the touch. There was extensive bruising on the medial thigh which extended up to the left inguinal region. Haematology results revealed mild regenerative anaemia, thrombocytopenia and mild mature neutrophilia. Creatine kinase and aspartate aminotransferase activities were increased. Activated clotting time, activated partial thromboplastin time and prothrombin time were within reference ranges. Examination using B-mode ultrasonography of the left thigh revealed a 49×70 mm fluid-filled structure. Using colour flow Doppler imaging the fluid-filled cavity was found to be communicating with the femoral artery and showed the yin/yang pattern typical of a pseudoaneurysm (Figure 1). The haematoma measured 120 mm in diameter. This was believed to be causing venous and lymphatic occlusion leading to oedema and development of compartment syndrome in the left thigh musculature. Based on the Doppler ultrasonography findings, there was evidence of arterial flow to the distal limb from the femoral artery.
A 5-year-old entire male working police German Shepherd dog presented with a 2-week history of left thigh swelling and distal limb oedema following a traumatic incident. It had been found with profuse haemorrhage from a puncture wound to the medial aspect of the left thigh after exercising in forest undergrowth. The handler applied direct pressure and the dog was presented to the referring veterinarian who found the haemorrhage to have stopped. The dog had pale mucous membranes, was in mild hypovolaemic shock and was treated with I/V fluid therapy. For
A decision was made to attempt repair of the pseudoaneurysm using ultrasound-guided thrombin injection, followed by fasciotomy to relieve the compartment syndrome. The dog was sedated, a 22G spinal needle was introduced into the lumen of the pseudoaneurysm, and bovine thrombin was injected incrementally into the pseudoaneurysm under ultrasound guidance until no further fluid flow could be seen within the structure. A total of 1800 IU bovine thrombin (Thrombin JMI; Jones Pharma Incorporated, Bristol VA, USA) was injected into the pseudoaneurysm. This resulted in thrombosis of the majority of the pseudoaneurysm, with a small pocket of residual filling of the pseudoaneurysm (approximately 10×5 mm) adjacent to the arterial laceration (Figure 2). The femoral artery was seen to be patent proximal and distal to the point of rupture after the thrombin injection. Treatment with oral meloxicam and potentiated amoxicillin and clindamycin was continued post procedure.
http://dx.doi.org/10.1080/00480169.2014.961991 © 2015 New Zealand Veterinary Association
Repeat ultrasonography performed 4 days after the thrombin injection revealed an increase in the size of the haematoma with a recurrent pseudoaneurysm around the femoral arterial tear.
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injection to attempt repair of a suspected femoral arterial pseudoaneurysm complicated by the development of compartment syndrome. Diagnosis of compartment syndrome is suspected based on clinical signs of pain, tenseness of limb, paresthesia, limb paresis and pulselessness. Definitive diagnosis can be achieved by measuring intracompartmental pressure either using invasive (manometry) or noninvasive (near infrared spectroscopy) techniques. However, it is generally agreed that clinical signs indicative of compartment syndrome warrant intervention without confirmation (Nielsen and Whelan 2012). If left untreated, compartment syndrome may result in loss of the limb, in which case amputation is required.
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Figure 1. Colour Doppler image of the left thigh of a 5-year-old male German Shepherd dog, showing a fluid-filled structure in close proximity to the femoral artery, with characteristic ‘yin-yang’ pattern typical of a pseudoaneurysm due to swirling pattern of blood flow. Red and blue colour flow signals are due to inflow and outflow turn of blood, respectively, via the neck of the pseudoaneurysm.
Figure 2. Colour Doppler image of the left thigh of a 5-year-old male German Shepherd dog, immediately after injection of thrombin into the lumen of a pseudoaneurysm, showing thrombosis of the majority of the pseudoaneurysm, with a small pocket of residual filling of the pseudoaneurysm adjacent to the arterial laceration.
There was an improvement in the nature of the arterial flow wave with improvement in perfusion. The dog remained pyrexic and continued to deteriorate with worsening of the limb oedema. Surgical exploration was undertaken to attempt primary repair of the vascular lesion, but was not achievable due to the irregular nature and length of the arterial laceration. The femoral artery was ligated proximal and distal to the tear, and the surgical site was lavaged with warm saline to remove as much of the haematoma as possible. Dead space closure was facilitated by the placement of a gravitationally dependant, egress-only, Penrose drain which was aseptically maintained for 48 hours. Post-operatively, the foot was warm with strong pulses in the dorsal pedal artery, and the dog received injectable buprenorphine and oral meloxicam. The patient was discharged from the hospital 1 week after surgery with a marked reduction in limb oedema and improved limb function. The dog was reported to be well and actively working as a search and rescue dog 5 years post surgery. To the authors’ knowledge, this is the first case in the veterinary literature reported to receive ultrasound-guided bovine thrombin
Compartment syndrome has rarely been described in the veterinary literature and has most commonly been reported in horses after prolonged periods of anaesthesia (Dodman et al. 1988). Two case reports of acute compartment syndrome in dogs following femoral fractures have been described (DeHaan and Beale 1993). Both these cases were successfully managed with surgery for fracture fixation and stabilisation. Femoral compartment syndrome secondary to haemorrhage from intramuscular haemangiosarcoma has been reported in dogs (Bar-Am et al. 2006; Radke et al. 2006). There is a single-case report describing compartment syndrome in the thigh of a Labrador Retriever secondary to a femoral arterial pseudoaneurysm following blunt trauma (Williams et al. 1993). The diagnosis in that case was made on ultrasonographic examination of the swollen thigh and confirmed with the help of an angiogram. The femoral artery was ligated proximal and distal to the tear after confirming good collateral blood supply distal to the ligation. The case presented here developed compartment syndrome secondary to a large femoral arterial pseudoaneurysm developed as a result of trauma to the medial thigh. Fasciotomy and open surgical repair in our case was delayed initially due to the high risk of fatal haemorrhage. This decision was made bearing in mind the risk associated with damage to the neurovascular structures in the affected thigh necessitating limb amputation in the future. It was deemed prudent to address the actively expanding haematoma and pseudoaneurysm prior to performing a fasciotomy to relieve the femoral compartment syndrome. Differential diagnoses of pseudoaneurysms include haematoma, abscess, arteriovenous fistula, lymphadenopathy, lymphocoele, deep venous thrombosis and compartment syndrome. Diagnosis of a pseudoaneurysm can be achieved by using duplex Doppler ultrasonography, arteriography, computed tomographic angiography and magnetic resonance angiography (Llabres-Diaz et al. 2010). Pseudoaneurysms may undergo spontaneous thrombosis or may lead to complications such as infection, development of local compression on neurovascular structures, or rupture. In humans, rupture is the most serious cause of morbidity from pseudoaneurysms. There is currently no way to predict which pseudoaneurysms will undergo spontaneous thrombosis and it is currently recommended in the human literature to treat all pseudoaneurysms measuring larger than 2.5 cm in diameter (Corriere and Guzman 2005). Treatment options for pseudoaneurysms include primary vascular repair, endovascular procedures (embolisation, stent-graft placement), ultrasound-guided compression repair and ultrasound-
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guided thrombin injection. The use of noninvasive treatment using ultrasound-guidance has led to a marked decrease in the morbidity and mortality rates for pseudoaneurysms in human patients (Pezzulo et al. 2000; Paulson et al. 2001; Saad et al. 2005).
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Ultrasound-guided compression involves compression of the pseudoaneurysm neck with the sonography transducer resulting in stasis and subsequent thrombosis of the blood in the pseudoaneurysm sac. Major disadvantages of this technique include failure rates of 15–38%, high recurrence rates in patients receiving anticoagulation medication and long compression times (Lennox et al. 1998). In addition, the procedure is painful for the patient and may necessitate I/V sedation (Pezzulo et al. 2000). Ultrasound-guided thrombin injection is currently the preferred method for treating femoral pseudoaneurysm in humans because of its low risk, high success rate, and efficacy in patients receiving anticoagulants (Corso et al. 2003). Use of autologous thrombin in human patients has been shown to be reliable, simple and safe (Quarmby et al. 2002). Complications with this technique are uncommon. The most serious complication is distal arterial embolisation, with a frequency of about 2% (Paulson et al. 2001). Open repair of pseudoaneurysm is recommended in the presence of infection, rapid expansion, or if less-invasive methods are not technically feasible (Corriere and Guzman 2005; Saad et al. 2005). Use of endovascular stenting for treatment of pseudoaneurysms in elective and emergency settings have been reported in humans. This can be done by using covered stents or by coil embolisation (Sadat et al. 2008). Based on human guidelines, the large size (greater than 3 cm diameter) of the pseudoaneurysm in the present case precluded the use of ultrasound-guided compression. Although there was a marked reduction in the size of the pseudoaneurysm (from 4 to 2 cm) on repeat examination 4 days after the thrombin injection, there was worsening of the distal limb oedema. Repeat injection was not undertaken due to concerns about worsening of the compartment syndrome and the signs of increasing pain in the dog. In the presence of uncertainty regarding the efficacy of bovine thrombin in the dog, decompression of the femoral compartment and open surgical repair of the femoral arterial defect was deemed essential. Primary repair of the vascular defect was attempted intra-operatively but proved to be futile due to the friable nature of the tissues. Ligation of the femoral artery proximal and distal to the defect was carried out based on the knowledge of the adequacy of collateral circulation to the distal limb in the dog, as has been previously suggested (Conrad et al. 1971; DeHaan and Beale 1993). A good clinical outcome was ultimately achieved with the dog resuming search and rescue work. The definitive cause of pyrexia in the current case remains unknown. We suspect it to be due to pain or production of endogenous pyrogens. There was no indication that the fever was of infectious origin. Haematology results were within reference range and the dog had been treated with potentiated amoxicillin prior to referral. Antimicrobial therapy was continued throughout the period of hospitalisation. The dog remained pyrexic despite this and only resolved after open surgical approach to relieve the compartment syndrome and debridement of the hematoma surrounding the femoral artery.
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Deficiencies in the diagnostic work-up in the present case include lack of information regarding the size of the defect in the femoral artery and the assessment of collateral circulation in the distal limb prior to surgery and following ligation of the femoral artery. Both these parameters could have been assessed with either conventional angiography or computed tomographic angiography. A complete work-up helps in determining location, morphologic features and rupture risk as well as aiding in identifying any comorbidities. This information, along with evaluation of the surrounding structures and relevant vascular anatomy could have helped with selection of appropriate treatment strategy. Endovascular stenting was not attempted in our case due to the non-availability of required instrumentation. The dose of bovine thrombin used was extrapolated from the human literature and may have been insufficient to achieve a good clinical response in this case. Moreover, it remains to be seen if repeating the procedure 24 hours after the initial thrombin injection would have achieved a successful outcome as reported in the human literature (Quarmby et al. 2002). The dog tolerated bovine thrombin without any identified adverse effects. Further studies are warranted in order to determine the type and dose of thrombin required in dogs to achieve optimal results. Historically pseudoaneurysms are considered uncommon in veterinary patients, however with the use of minimally invasive per-catheter vascular occlusion and dilation procedures gaining popularity in veterinary medicine during the past decade they could become more frequently recognised in the future. Early identification and treatment of pseudoaneurysm could prevent further complications such as development of compartment syndrome and loss of limb function.
References Bar-am Y, Anug AM, Shahar R. Femoral compartment syndrome due to haemangiosarcoma in the semimembranosus muscle in a dog. Journal of Small Animal Practice 47, 286–9, 2006 Basinger RR, Aron DN, Crowe DT, Purinton PT. Osteofascial Compartment Syndrome in the Dog. Veterinary Surgery 16, 427–34, 1987 Conrad M, Anderson JL, Garrett JB. Chronic collateral growth after femoral artery occlusion in the dog. Journal of Applied Physiology 31, 550–5, 1971 Corriere MA, Guzman RJ. True and false aneurysms of the femoral artery. Seminars in Vascular Surgery 18, 216–23, 2005 Corso R, Carrafiello G, Intotero M. Large iatrogenic pseudoaneurysm of the posterior tibial artery treated with sonographically guided thrombin injection. American Journal of Roentgenology 180, 1479–80, 2003 DeHaan JJ, Beale BS. Compartment syndrome in the dog—case report and literature review. Journal of the American Animal Hospital Association 29, 134–40, 1993 Demirbas O, Batyraliev T, Eksi Z, Pershukov I. Femoral Pseudoaneurysm Due to Diagnostic or Interventional Angiographic Procedures. Angiology 56, 553–6, 2005 Dodman NH, Williams R, Court MH, Norman WN. Postanesthetic hind limb adductor myopathy in five horses. Journal of the American Veterinary Medical Association 193, 83–6, 1988 Kang SS, Labropoulos N, Mansour MA, Michelini M, Filliung D, Bauby MP, Baker WH. Expanded indications for ultrasound-guided thrombin injection of pseudoaneurysms. Journal of Vascular Surgery 31, 289–98, 2000 Lenartova M, Tak T. Iatrogenic Pseudoaneurysm of femoral artery: case report and literature review. Clinical Medicine and Research 1, 243–7, 2003 Lennox A, Griffin M, Nicolaides AN. Percutaneous ultrasound guided thrombin injection: a new method for treating post-catheterization femoral pseudoaneurysms. Journal of Vascular Surgery 28, 1120–1, 1998 Llabres-Diaz FJ, Brissot H, Ibarrola P. Imaging diagnosis-celiac artery pseudoaneurysm associated with a migrating grass awn. Veterinary Radiology and Ultrasound 51, 508–11, 2010
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Nielsen LK, Whelan M. Compartment syndrome: pathophysiology, clinical presentations, treatment, and prevention in human and veterinary medicine. Journal of Veterinary Emergency and Critical Care 22, 291–302, 2012 Paulson EK, Nelson RC, Mayes CE. Sonographically guided thrombin injection of iatrogenic femoral pseudoaneurysms. Further experience of a single institution. American Journal of Roentgenology 177, 309–16, 2001 Pezzulo JA, Dupuy DE , Cronan JJ. Percutaneous injection of thrombin for the treatment of pseudoaneurysms after catheterization: An alternative to sonographically guided compression. American Journal of Roentgenology 175, 1035–40, 2000 Polak JF. Peripheral arterial disease. Evaluation with colour flow and duplex sonography. Radiologic Clinics of North America 33, 71–90, 1995 Quarmby JW, Engelke C, Chitolie A, Morgan RA, Belli AM. Autologous thrombin for treatment of pseudo-aneurysms. Lancet 359, 946–7, 2002 Radke H, Spreng D, Sigrist N, Lang J, Bornand V, Schawalder P. Acute compartment syndrome complicating an intramuscular haemangiosarcoma in a dog. Journal of Small Animal Practice 47, 281–4, 2006 Saad NAE, Saad WAE, Davies MG, Waldman DL, Fultz PJ, Rubens DJ. Pseudoaneurysms and the role of minimally invasive techniques in their management. Radiographics 25, 173–89, 2005
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Sadat U, Kullar PJ, Noorani A, Gillard JH, Cooper DG, Boyle JR. Emergency endovascular management of peripheral artery aneurysms and pseudoaneurysms – a review. World Journal of Emergency Surgery 3, 22, 2008 Williams J, Bailey MQ, Schertel ER, Valentine A. Compartment syndrome in a labrador retriever. Veterinary Radiology and Ultrasound 34, 244–8, 1993
A Tikekar and HR Milner Vetspecs 90 Disraeli Street Addington Christchurch 8024 New Zealand Email: [email protected]
Submitted 5 March 2014 First published online 09 September 2014
New Zealand Veterinary Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnzv20
Diagnosis and treatment of a suspected pseudoaneurysm of the femoral artery in a working police dog a
A Tikekar & HR Milner
a
a
Vetspecs 90 Disraeli Street Addington Christchurch 8024 New Zealand Accepted author version posted online: 09 Sep 2014.Published online: 05 Feb 2015.
Click for updates To cite this article: A Tikekar & HR Milner (2015) Diagnosis and treatment of a suspected pseudoaneurysm of the femoral artery in a working police dog, New Zealand Veterinary Journal, 63:2, 121-124, DOI: 10.1080/00480169.2014.961991 To link to this article: http://dx.doi.org/10.1080/00480169.2014.961991
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
New Zealand Veterinary Journal 63(2), 121–124, 2015
121
Peer-reviewed Correspondence
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Diagnosis and treatment of a suspected pseudoaneurysm of the femoral artery in a working police dog
An aneurysm is a localised saccular or fusiform dilation of the arterial wall and arises from weakening in the tunica media of the arterial wall, with intact but stretched tunica intima and adventitia. Pseudoaneurysms are localised haematomas with a persistent communication with the native artery or vein via a narrow neck. These lesions lack a fibrous wall and are contained by a surrounding shell of haematoma and the overlying soft tissues. Pseudoaneurysms are caused by rupture of a true aneurysm or by direct trauma to the artery. True aneurysms are differentiated from pseudoaneurysms only by histology (Williams et al. 1993). However, detection of a neck connecting a pseudoaneurysm with the injured artery using colour Doppler ultrasonography, and identification of turbulent blood flow within this neck is considered to be a hallmark of a pseudoaneurysm. The positive diagnostic rate of colour Doppler ultrasonography is reported to be about 95% in the human literature (Demirbas et al. 2005). Colour Doppler ultrasound examination is considered to be a sufficient and effective tool for the diagnosis of pseudoaneurysms. In humans, most peripheral pseudoaneurysms are iatrogenic following interventional catheterisation procedures or, less commonly, are post-traumatic (Lenartova and Tak 2003). Venous pseudoaneurysms have a low incidence of clinical sequelae but arterial pseudoaneurysms have unpredictable behaviour and their morbidities in humans include expansion, rupture, arterial thrombosis and distal embolisation (Kang et al. 2000). Diagnosis of an arterial pseudoaneurysm is best made on clinical findings and by colour duplex ultrasonography. There may be a pulsatile palpable mass that demonstrates a ‘yin/yang’ or a ‘to and fro’ pattern on colour flow Doppler or Doppler waveform analysis, respectively (Polak 1995). We report here a case of a post-traumatic femoral arterial pseudoaneurysm in a dog complicated by femoral compartment syndrome. Compartment syndrome is defined as a dysfunction of organs or tissues within a compartment that develops secondary to increased pressures within that compartment. Inelastic tissue such as fascia and bone can form a compartment in the extremities. Four such osteofascial compartments have previously been described in dogs (Basinger et al. 1987).
the first 4 days following this incident weight bearing was good on the affected limb. Subsequently distal limb oedema developed, with pyrexia and decreased weight bearing. Foreign body cellulitis from a putative stick penetration was suspected. Clinical signs of limb swelling, pyrexia and limb disuse worsened over the following week despite the use of antibiotics, diuretics and non-steroidal anti-inflammatory drugs. Specialist referral for further evaluation was then sought. On presentation the dog was pyrexic (temperature 39.4°C) and the left thigh was swollen to approximately twice the contralateral hindlimb. The limb felt firm and was painful on palpation. Oedema was present from the left stifle distally to the digits. The paw was warm to the touch. There was extensive bruising on the medial thigh which extended up to the left inguinal region. Haematology results revealed mild regenerative anaemia, thrombocytopenia and mild mature neutrophilia. Creatine kinase and aspartate aminotransferase activities were increased. Activated clotting time, activated partial thromboplastin time and prothrombin time were within reference ranges. Examination using B-mode ultrasonography of the left thigh revealed a 49×70 mm fluid-filled structure. Using colour flow Doppler imaging the fluid-filled cavity was found to be communicating with the femoral artery and showed the yin/yang pattern typical of a pseudoaneurysm (Figure 1). The haematoma measured 120 mm in diameter. This was believed to be causing venous and lymphatic occlusion leading to oedema and development of compartment syndrome in the left thigh musculature. Based on the Doppler ultrasonography findings, there was evidence of arterial flow to the distal limb from the femoral artery.
A 5-year-old entire male working police German Shepherd dog presented with a 2-week history of left thigh swelling and distal limb oedema following a traumatic incident. It had been found with profuse haemorrhage from a puncture wound to the medial aspect of the left thigh after exercising in forest undergrowth. The handler applied direct pressure and the dog was presented to the referring veterinarian who found the haemorrhage to have stopped. The dog had pale mucous membranes, was in mild hypovolaemic shock and was treated with I/V fluid therapy. For
A decision was made to attempt repair of the pseudoaneurysm using ultrasound-guided thrombin injection, followed by fasciotomy to relieve the compartment syndrome. The dog was sedated, a 22G spinal needle was introduced into the lumen of the pseudoaneurysm, and bovine thrombin was injected incrementally into the pseudoaneurysm under ultrasound guidance until no further fluid flow could be seen within the structure. A total of 1800 IU bovine thrombin (Thrombin JMI; Jones Pharma Incorporated, Bristol VA, USA) was injected into the pseudoaneurysm. This resulted in thrombosis of the majority of the pseudoaneurysm, with a small pocket of residual filling of the pseudoaneurysm (approximately 10×5 mm) adjacent to the arterial laceration (Figure 2). The femoral artery was seen to be patent proximal and distal to the point of rupture after the thrombin injection. Treatment with oral meloxicam and potentiated amoxicillin and clindamycin was continued post procedure.
http://dx.doi.org/10.1080/00480169.2014.961991 © 2015 New Zealand Veterinary Association
Repeat ultrasonography performed 4 days after the thrombin injection revealed an increase in the size of the haematoma with a recurrent pseudoaneurysm around the femoral arterial tear.
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injection to attempt repair of a suspected femoral arterial pseudoaneurysm complicated by the development of compartment syndrome. Diagnosis of compartment syndrome is suspected based on clinical signs of pain, tenseness of limb, paresthesia, limb paresis and pulselessness. Definitive diagnosis can be achieved by measuring intracompartmental pressure either using invasive (manometry) or noninvasive (near infrared spectroscopy) techniques. However, it is generally agreed that clinical signs indicative of compartment syndrome warrant intervention without confirmation (Nielsen and Whelan 2012). If left untreated, compartment syndrome may result in loss of the limb, in which case amputation is required.
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Figure 1. Colour Doppler image of the left thigh of a 5-year-old male German Shepherd dog, showing a fluid-filled structure in close proximity to the femoral artery, with characteristic ‘yin-yang’ pattern typical of a pseudoaneurysm due to swirling pattern of blood flow. Red and blue colour flow signals are due to inflow and outflow turn of blood, respectively, via the neck of the pseudoaneurysm.
Figure 2. Colour Doppler image of the left thigh of a 5-year-old male German Shepherd dog, immediately after injection of thrombin into the lumen of a pseudoaneurysm, showing thrombosis of the majority of the pseudoaneurysm, with a small pocket of residual filling of the pseudoaneurysm adjacent to the arterial laceration.
There was an improvement in the nature of the arterial flow wave with improvement in perfusion. The dog remained pyrexic and continued to deteriorate with worsening of the limb oedema. Surgical exploration was undertaken to attempt primary repair of the vascular lesion, but was not achievable due to the irregular nature and length of the arterial laceration. The femoral artery was ligated proximal and distal to the tear, and the surgical site was lavaged with warm saline to remove as much of the haematoma as possible. Dead space closure was facilitated by the placement of a gravitationally dependant, egress-only, Penrose drain which was aseptically maintained for 48 hours. Post-operatively, the foot was warm with strong pulses in the dorsal pedal artery, and the dog received injectable buprenorphine and oral meloxicam. The patient was discharged from the hospital 1 week after surgery with a marked reduction in limb oedema and improved limb function. The dog was reported to be well and actively working as a search and rescue dog 5 years post surgery. To the authors’ knowledge, this is the first case in the veterinary literature reported to receive ultrasound-guided bovine thrombin
Compartment syndrome has rarely been described in the veterinary literature and has most commonly been reported in horses after prolonged periods of anaesthesia (Dodman et al. 1988). Two case reports of acute compartment syndrome in dogs following femoral fractures have been described (DeHaan and Beale 1993). Both these cases were successfully managed with surgery for fracture fixation and stabilisation. Femoral compartment syndrome secondary to haemorrhage from intramuscular haemangiosarcoma has been reported in dogs (Bar-Am et al. 2006; Radke et al. 2006). There is a single-case report describing compartment syndrome in the thigh of a Labrador Retriever secondary to a femoral arterial pseudoaneurysm following blunt trauma (Williams et al. 1993). The diagnosis in that case was made on ultrasonographic examination of the swollen thigh and confirmed with the help of an angiogram. The femoral artery was ligated proximal and distal to the tear after confirming good collateral blood supply distal to the ligation. The case presented here developed compartment syndrome secondary to a large femoral arterial pseudoaneurysm developed as a result of trauma to the medial thigh. Fasciotomy and open surgical repair in our case was delayed initially due to the high risk of fatal haemorrhage. This decision was made bearing in mind the risk associated with damage to the neurovascular structures in the affected thigh necessitating limb amputation in the future. It was deemed prudent to address the actively expanding haematoma and pseudoaneurysm prior to performing a fasciotomy to relieve the femoral compartment syndrome. Differential diagnoses of pseudoaneurysms include haematoma, abscess, arteriovenous fistula, lymphadenopathy, lymphocoele, deep venous thrombosis and compartment syndrome. Diagnosis of a pseudoaneurysm can be achieved by using duplex Doppler ultrasonography, arteriography, computed tomographic angiography and magnetic resonance angiography (Llabres-Diaz et al. 2010). Pseudoaneurysms may undergo spontaneous thrombosis or may lead to complications such as infection, development of local compression on neurovascular structures, or rupture. In humans, rupture is the most serious cause of morbidity from pseudoaneurysms. There is currently no way to predict which pseudoaneurysms will undergo spontaneous thrombosis and it is currently recommended in the human literature to treat all pseudoaneurysms measuring larger than 2.5 cm in diameter (Corriere and Guzman 2005). Treatment options for pseudoaneurysms include primary vascular repair, endovascular procedures (embolisation, stent-graft placement), ultrasound-guided compression repair and ultrasound-
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New Zealand Veterinary Journal, 2015
guided thrombin injection. The use of noninvasive treatment using ultrasound-guidance has led to a marked decrease in the morbidity and mortality rates for pseudoaneurysms in human patients (Pezzulo et al. 2000; Paulson et al. 2001; Saad et al. 2005).
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Ultrasound-guided compression involves compression of the pseudoaneurysm neck with the sonography transducer resulting in stasis and subsequent thrombosis of the blood in the pseudoaneurysm sac. Major disadvantages of this technique include failure rates of 15–38%, high recurrence rates in patients receiving anticoagulation medication and long compression times (Lennox et al. 1998). In addition, the procedure is painful for the patient and may necessitate I/V sedation (Pezzulo et al. 2000). Ultrasound-guided thrombin injection is currently the preferred method for treating femoral pseudoaneurysm in humans because of its low risk, high success rate, and efficacy in patients receiving anticoagulants (Corso et al. 2003). Use of autologous thrombin in human patients has been shown to be reliable, simple and safe (Quarmby et al. 2002). Complications with this technique are uncommon. The most serious complication is distal arterial embolisation, with a frequency of about 2% (Paulson et al. 2001). Open repair of pseudoaneurysm is recommended in the presence of infection, rapid expansion, or if less-invasive methods are not technically feasible (Corriere and Guzman 2005; Saad et al. 2005). Use of endovascular stenting for treatment of pseudoaneurysms in elective and emergency settings have been reported in humans. This can be done by using covered stents or by coil embolisation (Sadat et al. 2008). Based on human guidelines, the large size (greater than 3 cm diameter) of the pseudoaneurysm in the present case precluded the use of ultrasound-guided compression. Although there was a marked reduction in the size of the pseudoaneurysm (from 4 to 2 cm) on repeat examination 4 days after the thrombin injection, there was worsening of the distal limb oedema. Repeat injection was not undertaken due to concerns about worsening of the compartment syndrome and the signs of increasing pain in the dog. In the presence of uncertainty regarding the efficacy of bovine thrombin in the dog, decompression of the femoral compartment and open surgical repair of the femoral arterial defect was deemed essential. Primary repair of the vascular defect was attempted intra-operatively but proved to be futile due to the friable nature of the tissues. Ligation of the femoral artery proximal and distal to the defect was carried out based on the knowledge of the adequacy of collateral circulation to the distal limb in the dog, as has been previously suggested (Conrad et al. 1971; DeHaan and Beale 1993). A good clinical outcome was ultimately achieved with the dog resuming search and rescue work. The definitive cause of pyrexia in the current case remains unknown. We suspect it to be due to pain or production of endogenous pyrogens. There was no indication that the fever was of infectious origin. Haematology results were within reference range and the dog had been treated with potentiated amoxicillin prior to referral. Antimicrobial therapy was continued throughout the period of hospitalisation. The dog remained pyrexic despite this and only resolved after open surgical approach to relieve the compartment syndrome and debridement of the hematoma surrounding the femoral artery.
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Deficiencies in the diagnostic work-up in the present case include lack of information regarding the size of the defect in the femoral artery and the assessment of collateral circulation in the distal limb prior to surgery and following ligation of the femoral artery. Both these parameters could have been assessed with either conventional angiography or computed tomographic angiography. A complete work-up helps in determining location, morphologic features and rupture risk as well as aiding in identifying any comorbidities. This information, along with evaluation of the surrounding structures and relevant vascular anatomy could have helped with selection of appropriate treatment strategy. Endovascular stenting was not attempted in our case due to the non-availability of required instrumentation. The dose of bovine thrombin used was extrapolated from the human literature and may have been insufficient to achieve a good clinical response in this case. Moreover, it remains to be seen if repeating the procedure 24 hours after the initial thrombin injection would have achieved a successful outcome as reported in the human literature (Quarmby et al. 2002). The dog tolerated bovine thrombin without any identified adverse effects. Further studies are warranted in order to determine the type and dose of thrombin required in dogs to achieve optimal results. Historically pseudoaneurysms are considered uncommon in veterinary patients, however with the use of minimally invasive per-catheter vascular occlusion and dilation procedures gaining popularity in veterinary medicine during the past decade they could become more frequently recognised in the future. Early identification and treatment of pseudoaneurysm could prevent further complications such as development of compartment syndrome and loss of limb function.
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Tikekar and Milner
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A Tikekar and HR Milner Vetspecs 90 Disraeli Street Addington Christchurch 8024 New Zealand Email: [email protected]
Submitted 5 March 2014 First published online 09 September 2014
