Spontaneous Aortic Dissecting Hematoma in Two Dogs

Presumptive spontaneous hemothorax associated to thymic involution in a dog with steroid responsive meningitis-arteritis (SRMA)

OBJECTIVE

To describe an unusual case of spontaneous hemothorax resulting from thymic involution in a dog with suspected acquired bleeding dyscrasia associated with steroid-responsive meningitis-arteritis (SRMA).

CASE DESCRIPTION

A 6-month-old spayed female Golden Retriever was referred due to the sudden onset of lethargy, fever (pyrexia), loss of appetite (anorexia), and moderate neck pain. These symptoms emerged six days after an ovariohysterectomy performed by the primary veterinarian. Upon admission, the patient exhibited pale mucous membranes, tachycardia (180 bpm), bilateral muffled heart sounds and tachypnea. Abdominal and thoracic point-of-care ultrasound (POCUS) were performed and revealed bilateral pleural effusion. Due to the patient's unstable condition, emergent thoracocentesis and transfusion of packed red blood cells was required. The initial work-up performed included a complete blood cell count (CBC), biochemistry profile, venous blood gas and coagulation panel (PT, APTT, fibrinogen). Pleural effusion analysis was compatible with hemothorax. Bloodwork was unremarkable including the initial coagulation panel. Further coagulation test was performed including buccal mucosal bleeding time, viscoelastic-based clot detection tests (TEG) and Von Willebrand factor antigen measurement. TEG revealed marked hyperfibrinolysis. Angiostrongylus vasorum and 4DX snap test were performed and yielded a negative result. Thoracic CT scan revealed the presence of a soft tissue-attenuating mass in the ventral mediastinum, thymic involution, and enlargement of the sternal and mediastinal lymph nodes. Therapy with tranexamic acid and corticosteroids at anti-inflammatory doses was initiated. Marked clinical improvement was observed within 24 hours, and after three days of hospitalization the patient was discharged. One month later, the dog was referred again for acute pyrexia, hyporexia, and neck pain which progressed to non-ambulatory tetraparesis. Neurological examination was compatible with C6-T2 lesion. MRI and cerebrospinal fluid analysis were performed and revealed a final diagnosis of steroid-responsive meningitis-arteritis (SRMA) with associated intramedullary hemorrhage. Corticosteroids were started again, and the patient showed a dramatic improvement over the next 24 hours. Three weeks after the diagnosis, the dog returned to a clinically normal state. The treatment was gradually tapered over the following months, guided by regular neurological and clinical examinations and CRP measurements, without any relapses.

NEW OR UNIQUE INFORMATION

To the best of the author's knowledge, this is the first documented case of a dog experiencing spontaneous hemothorax as a result of thymic hemorrhage/involution which, in the absence of other identifiable diseases, was attributed to a hyperfibrinolytic state induced by a severe inflammatory disease such as SRMA.

Aneurysm Associated with Vascular Wall Degeneration in Bearded Dragons (Pogona vitticeps)

This study describes the clinical, gross, and histologic findings in 17 cases of aneurysms in bearded dragons (Pogona vitticeps). The clinical presentation ranged from incidental to sudden and unexpected death. The affected vasculature was predominantly arterial; however, based on the topographical locations of the lesions, gross structure, and drainage, some veins were likely involved. Magnetic resonance imaging and computerized tomography scans of 1 animal showed a large aneurysm of the internal carotid artery extending from near its aortic origin into the caudal head. Aneurysms were organized in 5 groups based on their anatomical locations: cephalic, cranial coelom (for all near the heart), caudal coelom (for the mesenteric vessels and descending aorta), limbs, and tail. The cranial coelomic region was the most prevalent location. Gross findings were large hematomas or red serosanguineous fluid filling the adjacent area, as most of the aneurysms (94%) were ruptured at the time of the study. The main histological findings were degenerative changes of the vessel walls characterized by moderate to severe disruption of the collagen and elastic fibers of the tunica media and adventitia (100%), followed by thickening of the intima with thrombi formation (54%) and dissecting hematoma of the vessel wall (47%). Vasculitis (29%), mineralization (6%), and lipid deposits (6%) in the vessel wall were observed occasionally. Based on these findings, the vascular dilations and ruptures observed in bearded dragons likely are associated with weakness of the vessel walls caused by degenerative changes in the intimal and medial tunics.

Annuloaortic ectasia in a four-month-old male Newfoundland dog: long-term follow-up and immunofluorescent study

A 4 month-old, 14.8 kg, male Newfoundland dog was presented for cardiovascular evaluation following detection of a heart murmur. Echocardiography revealed enlargement of the sinuses of Valsalva and marked, diffuse dilation of the ascending aorta (annuloaortic ectasia, AAE), with mild/equivocal subaortic stenosis (SAS). The dog was monitored over the duration of its lifetime, with serial echocardiograms performed at 5, 6, and 8 months and 1, 2, 3, 4, 8, and 10 years demonstrating persistent, diffuse dilation of the ascending aorta. The dog lived until it was 10 years old and died of metastatic carcinoma. Postmortem examination confirmed AAE and mild SAS. Hematoxylin and eosin and Weigert van Gieson stains were used to compare the ascending aorta to the descending aorta and left subclavian artery, and to compare aortic samples to those of three control dogs. Histopathologic evaluation revealed mild medial degeneration in the ascending aorta of all four dogs. Immunofluorescent microscopy was used for determining the deposition of proteins known to play a role in aortic aneurysms in humans: fibrillin-1 (FBN1), latent transforming growth factor beta binding protein 4 (LTBP4) and fibronectin. The ascending aorta of the AAE case demonstrated reduced deposition of FBN1, indicating that its loss may have contributed to aortic dilation. Diffuse, primary ascending aortic dilation is uncommonly reported in dogs; when it is, it carries a poor prognosis. This case provides an important example of marked dilation of the ascending aorta in a dog that lived with no associated adverse effects for 10 years.

Balloon expandable aortic stent-graft for the treatment of aortic aneurysm and rupture in a dog

OBJECTIVE

To describe the successful placement of an aortic stent graft in a dog suffering from aortic aneurysm and rupture.

CASE SUMMARY

A 4-year-old neutered female mixed breed dog weighing 25 kg was presented with a chief complaint of acute onset of weakness and respiratory distress. On presentation, the dog was lateral and unresponsive, hypothermic, tachycardic, and tachypneic. Pleural effusion was identified in the right hemi-thorax on thoracic-focused sonographic scan for trauma. Thoracic radiographs showed a fluid/soft tissue opacity in the cranial mediastinum and pleural effusion on the right side. Thoracocentesis yielded noncoagulating blood. Hematology revealed normal PCV and total plasma protein that decreased within 24 hours to 20% and 50 g/L (20%/5.0 g/dL), respectively. The dog was treated with IV fluids, tranexamic acid, and fresh frozen plasma. An aortic aneurysm with irregular mineralization of the right ventrolateral aortic wall was identified on computed tomography examination, which also demonstrated a peri-aortic hematoma. A decision was made to attempt treatment with a stent graft. Under general anesthesia, a marker catheter was inserted into the esophagus. A 10-Fr sheath was inserted into the right femoral artery, and an angiography catheter was advanced over a wire. After angiography, a stent graft (12-mm × 50-mm) was placed over the guide wire and deployed under fluoroscopic guidance. The dog recovered uneventfully, with no evidence of recurrent bleeding, and was discharged 2 days after the procedure with antimicrobials, anthelmintic, and antithrombotic treatment. At 90-day follow-up, the dog was doing well, and stent position was radiographically confirmed.

NEW OR UNIQUE INFORMATION PROVIDED

This report describes successful management of aortic aneurysm and dissection, an uncommon and challenging pathology in the veterinary practice with few available treatment options. Stent graft placement is a minimally invasive procedure in which a covered stent is placed over the lesion to prevent rupture.

Dorsal mediastinal haemorrhage in dogs: four cases (2010-2018)

OBJECTIVE

This retrospective case series describes the clinical presentation and CT findings of dogs with presumed mediastinal haemorrhage with no apparent identifiable underlying cause.

MATERIALS AND METHODS

Medical records were searched for dogs with presumed or suspected mediastinal haemorrhage of non-thymic origin. For all dogs, data on signalment, history, physical examination, treatment and outcome were collected by reviewing the medical records. Follow-up information was collected by telephone interviews with the owners and/or their primary-care veterinarians.

RESULTS

Four dogs were included. All survived to discharge with apparent resolution of the mediastinal haemorrhage (based on repeat imaging and/or clinical signs) with supportive treatment alone. Follow-up information was available from 2 months to 5 years following discharge, and none of the patients showed a recurrence of clinical signs during this period.

CLINICAL SIGNIFICANCE

This case series highlights that presumed haemorrhage into the mediastinum can occur in dogs without an obviously identifiable cause and, whilst rare, should be considered as a cause of dorsal mediastinal masses and may be successfully managed with supportive care alone.

Age-Related Changes in the Canine Aorta

Degenerative changes in the aorta are commonly observed in both dogs and humans, and those changes that occur with age morphologically overlap with those observed in genetic or degenerative diseases. Therefore, recognition of age-related aortic changes is important for diagnosticians, as such histologic findings should be distinguished from lesions of specific diseases. The aortas from 37 dogs without clinical cardiovascular disease ranging in age from 2 months to 15 years were divided into 3 cohorts to assess age-relatedness, and evaluated histologically using standardized nomenclature and diagnostic criteria adapted and modified from the human literature. We found that the histopathologic severity scores for intimal thickening, translamellar medial fibrosis, loss of smooth muscle cell nuclei, and medial microcalcification were higher in older dogs, whereas the scores for both intralamellar and translamellar mucoid extracellular matrix accumulation ("cystic medial necrosis") were not different among age groups. Dogs with translamellar medial fibrosis and aortic medial microcalcification were significantly older compared with dogs without these findings, while the presence of aortic medial chondro-osseous metaplasia was not related to age. Taken together, we demonstrate a range of age-related aortic histologic changes in dogs without clinical cardiovascular disease and suggest that integration of signalment and clinical data can aid in the differentiation of such findings from non-age-related disease processes.

Aortic dissection in four cats: clinicopathological correlations

Aortic dissection (AD) is characterized by bleeding within the aortic wall or a tear in the intimal layer of the aortic wall, resulting in the passage of blood from the aortic lumen into the tunica media. In cases of AD, a floating, intimal flap in the aortic lumen divides the lumen into a true portion, with flow present, and a false portion, with no flow. We describe a series of 4 cats with AD of the ascending aorta and moderate aortic insufficiency. Three cats had an acute onset of clinical signs with pericardial effusion and cardiac tamponade, whereas one cat showed a chronic onset without pericardial effusion. Detailed gross and histopathological characterization is available for two cats, which revealed the typical features of AD. One cat also showed connective tissue abnormalities, microscopically resembling Marfan-like syndrome. Concomitant detection of hypertrophic cardiomyopathy in 2 cats represents a novel finding in the veterinary literature. Feline AD is generally associated with systemic hypertension. In all the cats of this case series, blood pressure was normal at presentation, although systemic hypertension before the acute dissection cannot be ruled out. In humans, hypotension is more common with AD of the ascending aorta, so the anatomical location could also play a role in cats. Hypertrophic cardiomyopathy in cats could have been a potential trigger of AD through shear stress. Transthoracic echocardiography, as herein demonstrated, can be considered as a rapid, non-invasive and useful method for the diagnosis of dissection at the level of the ascending aorta.

Left subclavian artery dissection associated with connective tissue abnormalities resembling Marfan-like syndrome in an English bulldog

The unexpected demise of a 12-year-old male neutered English bulldog solicited a gross examination, which revealed a blood-filled space occurring in the proximal left subclavian artery (LSA). It originated about 1 cm from the branching point of the vessel and progressively dilated for 3 cm distal to this origin. Histopathological investigation showed that the tunica media of the LSA was more than 50% split, with the blood-filled space dissecting through the arterial wall. In the tunica media of the LSA, severe multifocal fragmentation and/or loss of the elastic fibers was observed. The retained disorganized elastic fibers were separated and disoriented due to accumulations of acid mucopolysaccharide. Marked, diffuse medial, and adventitial fibrous tissue deposition was also identified. The cause of death was attributed to acute hemorrhagic and necrotizing pancreatitis with pulmonary edema, suggesting that LSA dissection was an incidental finding. Subclavian artery dissection is extremely rare in humans, where the involvement of the LSA in cases of aortic dissection both with or without Marfan syndrome has been reported. Aortic and pulmonary artery dissection in bovines and aortic aneurysm and dissection in dogs have been reported to be associated with Marfan and Marfan-like syndromes, respectively. Histopathological findings suggestive of underlying connective tissue abnormalities resembling Marfan-like syndrome (i.e., the appearance of the elastic tissue and the degenerative changes of the tunica media) were detected in the first case of LSA dissection in dogs and veterinary medicine, herein described.

Retrospective multicenter evaluation of the "fly-catching syndrome" in 24 dogs: EEG, BAER, MRI, CSF findings and response to antiepileptic and antidepressant treatment

The fly-catching syndrome (FCS) is a rare canine condition of sudden, occasional, or constant episodes of biting the air. It may be accompanied by jumping, licking, and swallowing. The etiology of FCS is unknown and controversial. Various explanations for its occurrence have included epileptoid disorders such as visual cortex epileptiform disturbances and simple and complex partial seizures as well as compulsive disorders, hallucinatory behavior, and stereotypy. A retrospective multicenter analysis of 24 dogs with clinical symptoms of FCS is presented. Clinical signs at the time of presentation, the mean age at onset of the disease, the response to treatment, and the clinical outcome were recorded and analyzed in all patients. All dogs underwent clinical, neurological, and otoscopic examinations. Complete blood cell counts (CBCs) and serum chemistry panels were obtained from each dog. Diagnostic testing included MRI and EEG examinations in 21 cases, BAER in 19 cases, and CSF analysis in 20 cases. The EEG revealed spike activity in 8 (38%) of the 21 cases, 7 of which had activity in the occipital lobes. The brainstem auditory evoked response (BAER) revealed three cases of bilateral deafness. The MRI revealed six cases of Chiari malformation (CM), one case of syringohydromyelia (SM), and one case of a falx cerebri meningioma. The dogs were divided into groups according to their treatment protocol. Group A included dogs treated with phenobarbital (PB), and group B consisted of dogs treated with fluoxetine (FLX). Thirty-six percent of the dogs in group A responded to PB, while 100% of the dogs in group B responded to FLX. The results suggest that FCS is more responsive to FLX than PB. However, the etiology of this behavior remains unclear in most cases.

Pulmonary artery dissection in eight dogs with patent ductus arteriosus

OBJECTIVES

To describe a series of dogs with pulmonary artery dissection and patent ductus arteriosus (PDA).

ANIMALS

Eight dogs.

METHODS

Retrospective case series.

RESULTS

Pulmonary artery dissection was diagnosed in 8 dogs, 3 were Weimaraners. Four dogs presented in left-sided congestive heart failure, 4 presented for murmur evaluation and without clinical signs, and 1 presented in right-sided congestive heart failure. In 7 dogs the dissection was first documented concurrent with a diagnosis of uncorrected PDA. In the other dog, with pulmonary valve stenosis and PDA, the dissection was observed on autopsy examination 17 months after balloon pulmonary valvuloplasty and ductal closure. Median age at presentation for the 7 dogs with antemortem diagnosis of pulmonary artery dissection was 3.5 years (range, 1.5-4 years). Three dogs had the PDA surgically ligated, 2 dogs did not undergo PDA closure, 1 dog failed transcatheter occlusion of the PDA with subsequent surgical ligation, 1 dog underwent successful transcatheter device occlusion of the PDA, and 1 dog had the PDA closed by transcatheter coil delivery 17 months prior to the diagnosis of pulmonary artery dissection. The 2 dogs that did not have the PDA closed died 1 and 3 years after diagnosis due to heart failure.

CONCLUSIONS

Pulmonary artery dissection is a potential complication of PDA in dogs, the Weimaraner breed may be at increased risk, presentation is often in mature dogs, and closure of the PDA can be performed and appears to improve outcome.

Unilateral shunt formation with thoracic aortic dissection in a whippet

A three-year-old neutered male whippet was presented with intermittent, exercise-induced paraparesis. Femoral pulses were bilaterally absent. Neurologic examination was suggestive of a thoracolumbar myelopathy. Blood pressure measurements revealed hypotension in both pelvic limbs, hypertension in the right thoracic limb and it was immeasurable in the left thoracic limb. Echocardiography was within reference limits. A clear vascular pulsation was palpable on the right ventral abdominal wall. Computed tomographic angiography revealed a dissection of the aortic wall between the left subclavian artery and the brachiocephalic trunk with subsequent thrombus formation. A shunt between the right internal thoracic, cranial and caudal epigastric arteries to preserve blood flow to the pelvic limbs was visualized. Necropsy was declined by the owner. This is the first case report describing the formation of a unilateral vascular shunt following a thoracic aortic occlusion, which presented as exercise-induced paraparesis.