A 10 year old, male-neutered, medium sized, mixed breed dog was presented with a one-week history of progressive neurological signs. Initially, the dog was dull and showed a low head carriage. Clinical signs progressed to pacing in circles to the right, dysphoria, and suspected right sided visual deficits. There was no travel history. The dog was regularly vaccinated and dewormed.
The dog was presented in lateral recumbency. The dog was stuporous. Rectal body temperature was 38.2 C. Breathing pattern was normal, frequency was 34/min with physiological effort. Auscultation revealed mildly increased vesicular sounds, which were interpreted as still within physiological limits. On cardiac auscultation the heartbeat was regular with 90 bpm, no heart murmur was audible. Femoral pulses were strong, regular, and synchronous with heartbeat. Capillary refill time was under 2 s, the mucous membranes were pale-pink and mildly sticky on palpation. Macroscopical evaluation of eyes, external ears, nose, and skin were unremarkable.
The owner declined any further diagnostic attempt or therapy. After 3 h in the clinic, the dog suffered spontaneous cardio-respiratory arrest and died.
Macroscopically, an approximately 4 cm in diameter sized accumulation of coagulated blood was found within the lateral ventricle of the left hemisphere of the brain (Figure 3A). The adjacent brain parenchyma showed multifocal hemorrhages. Other findings comprised mild endocardiosis of the atrioventricular valve as well as multiple nodular masses within the spleen. Histopathologically, focal, severe hemorrhage corresponding to the macroscopic finding was visible in the left lateral ventricle and the neighboring brain parenchyma. Furthermore, moderate to severe, lympho-histiocytic infiltrates were detected within the meninges and brain parenchyma, and associated with non-leukocytoclastic vasculitis, most frequently in the cerebral cortex, hippocampus, brain stem, and cerebellum (Figure 3B). Furthermore, similar, but mild inflammatory changes of leptomeningeal blood vessels were found in the cervical, thoracic, and lumbar spinal cord. Additionally, within the perineural tissue of the optic nerve of the left eye mild, lympho-histiocytic vasculitis was detected as well as a mild cataract. In between nerve fibers of the trigeminal nerve, moderate, focal, acute hemorrhage was found. Using IHC, perivascular infiltrates in the CNS comprised equal numbers of CD3- and CD20-positive lymphocytes and multifocal, irregular infiltration with few CD204-positive macrophages. Using IHC and histochemistry, no infectious agent or signs of demyelination were detected.
Further alterations of minor significance comprised mild, follicular hyperplasia in the tonsils and mild, multifocal anthracosis in the lung as well as mild, acute, diffuse, alveolar edema. The splenic nodules were diagnosed as nodular hyperplasia. No signs of parasites, e.g. Angiostrongylus vasorum, were found in the lungs, heart, gastrointestinal tract, or CNS via gross and macroscopic examination.