Successful surgical and medical treatment of a severe, acute epidural bleed in a young dog due to steroid responsive meningitis-arteritis

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.

Steroid-responsive meningitis-arteritis: What have we learned since 2010? A narrative review

Steroid-responsive meningitis-arteritis (SRMA) occurs as an immune-mediated, inflammatory, and non-infectious disorder of juvenile and young-adult dogs. In principle, SRMA is divided into two clinical courses: during the typical acute form, dogs are presented with fever, cervical hyperaesthesia, and reluctance to move. The more protracted form most probably emerges after insufficient immunosuppressive treatment or relapses, with additional neurologic deficits localized in the cervical and thoracolumbar spinal cord or multifocally. The trigger leading to SRMA still remains an unsolved riddle for immunologists and clinical neurologists. In the past, many attempts have been made to clarify the etiology of this disease without success. The purpose of writing this narrative review about SRMA is to summarize new insights on the pathogenesis of SRMA with a focus on immunologic dysregulation. Furthermore, unusual manifestations of the disease, new diagnostic approaches using possible laboratory biomarkers or diagnostic imaging tools, and potential innovative treatment strategies are discussed.

Hemophilia A Resulting in Severe Hyperesthesia Due to Extraparenchymal Spinal Cord Hemorrhage in a Young Golden Retriever Puppy

A ten-week-old male Golden retriever puppy was presented with severe hyperesthesia, mild neurological deficits and episcleral bleeding. Clotting times showed a normal prothrombin time (PT) and prolonged activated partial thromboplastin time (aPPT). Computed tomography (CT) of the vertebral column showed intradural, extraparenchymal hyperattenuating changes on precontrast CT images and epidural mass lesions, suggestive of hematorrhachis. Hemophilia A was confirmed by a low-factor VIII activity (FVIII:C). Although the dog improved clinically with intravenous analgesia and cage rest, it was euthanized by the owners’ choice because of the risk of developing future episodes of spontaneous hemorrhage. In young male puppies with severe hyperesthesia and mild neurological deficits, hemophilia A should be considered as a possible differential diagnosis.

Clinical, Diagnostic, and Imaging Findings in Three Juvenile Dogs With Paraspinal Hyperesthesia or Myelopathy as a Consequence of Hemophilia A: A Case Report

Three juvenile dogs presented with an acute onset of paraspinal hyperesthesia and/or neurologic deficits. These dogs underwent anesthesia for MRI and additional diagnostics. The thoracolumbar MRI in Dog 1 revealed an accumulation of T2-weighted (T2W) hyperintense, T1-weighted (T1W) iso- to hyperintense, contrast enhancing extradural material. The differential diagnoses were meningitis with secondary hemorrhage or empyema or late subacute hemorrhage. The initial cervical MRI in Dog 2 revealed T1W meningeal contrast enhancement suspected to be secondary to meningitis. A repeat MRI following neurologic decline after CSF sampling revealed a large area of T2W and T1W hyperintensity between fascial planes of the cervical musculature as well as T2W iso- to hyperintense and T1W iso- to hypointense extradural material at the level of C1 consistent with hemorrhage. The cervical MRI in Dog 3 revealed T2W hyperintense and T1W iso- to hypointense extradural compressive material consistent with hemorrhage. Dogs 1 and 2 underwent CSF sampling and developed complications, including subcutaneous hematoma and vertebral canal hemorrhage. Dog 3 underwent surgical decompression, which revealed a compressive extradural hematoma. In each case, a hemophilia panel including factor VIII concentration confirmed the diagnosis of hemophilia A. Dog 1 had a resolution of clinical signs for ~5 months before being euthanized from gastrointestinal hemorrhage. Dog 2 was euthanized due to neurologic decompensation following CSF sampling. Dog 3 did well for 2 weeks after surgery but was then lost to follow-up. This case series provides information on clinical signs, MRI findings, and outcome in 3 juvenile dogs with hemophilia A that developed neurologic deficits or paraspinal hyperesthesia secondary to spontaneous or iatrogenic vertebral canal hemorrhage. Hemophilia A should be considered as a differential in any young dog presenting with an acute onset of hyperesthesia with or without neurologic deficits. This diagnosis should be prioritized in young male dogs that have other evidence of hemorrhage on physical exam.