A 20-year-old Quarter horse gelding was referred for evaluation of an acute onset non-weight-bearing right forelimb lameness. Marked soft tissue swelling was apparent over the right scapula and shoulder region; no crepitus was palpable. A complete transverse fracture of the scapular neck was suspected based on ultrasonography and radiographs were obtained to confirm the presumptive diagnosis. A complete, oblique fracture of the right scapular neck with mild cranial and proximal displacement of the distal fragment was detected. Computed tomography of the upper right forelimb was performed post-mortem; lytic bony destruction of the scapular neck with a secondary pathologic fracture was observed. The lesion was considered most likely neoplastic. At necropsy a complete, comminuted fracture of the right scapula was confirmed, secondary to neoplastic invasion of the bone. A solitary, dorsally located, neoplastic mass was also observed within the parenchyma of the right caudal lung. Histopathologically, the lung and scapula lesions were similar, characteristic of a well-differentiated pulmonary carcinoma.

Intracranial neoplasia in horses is rare compared to other species. Detailed information such as neurological, electroencephalographic, and histopathological examination of horses with intracranial neoplasia associated with seizures is scarce in the literature. Furthermore, ganglioglioma has not been reported in the horse. A 7-year-old Quarter horse cross Paint gelding was examined due to recurrent seizure-like episodes of 1-year duration. The seizures had been increasing in frequency and length, occurring up to 20 times a day at the time of presentation. Neurological examination revealed intermittent obtundation and multiple left sided abnormalities consisting of upper motor facial and tongue hemiparesis, facial hyperesthesia and cervical hypoesthesia, proprioceptive deficits, thoracic limb hypermetria upon head elevation; and intermittent paroxysmal activity consistent with seizures. Cranial nerve reflexes were normal. Vocalization, conjugate vertical nystagmus, intermittent blindness, left sided head tilt and flexion of neck, and lack of response to environmental stimuli were observed during seizure activity. A right sided cerebrothalamic disease was suspected. An electroencephalogram confirmed seizure activity with main focus on the right side at the central, parietal, and occipital regions further supporting neuroanatomical localization. Additionally, subclinical paroxysmal activity was noted on the electroencephalogram. A ganglioglioma was identified in the right cerebrothalamic area, and other cranial parts of the brainstem based on immunohistochemical examination. To the authors knowledge this is the first report of intracranial ganglioglioma in the horse. This intracranial neoplasia should be added to the possible causes of intracranial masses and seizures in horses.

Intracranial neoplasia in horses is rare compared to other species. Detailed information such as neurological, electroencephalographic, and histopathological examination of horses with intracranial neoplasia associated with seizures is scarce in the literature. Furthermore, ganglioglioma has not been reported in the horse. A 7-year-old Quarter horse cross Paint gelding was examined due to recurrent seizure-like episodes of 1-year duration. The seizures had been increasing in frequency and length, occurring up to 20 times a day at the time of presentation. Neurological examination revealed intermittent obtundation and multiple left sided abnormalities consisting of upper motor facial and tongue hemiparesis, facial hyperesthesia and cervical hypoesthesia, proprioceptive deficits, thoracic limb hypermetria upon head elevation; and intermittent paroxysmal activity consistent with seizures. Cranial nerve reflexes were normal. Vocalization, conjugate vertical nystagmus, intermittent blindness, left sided head tilt and flexion of neck, and lack of response to environmental stimuli were observed during seizure activity. A right sided cerebrothalamic disease was suspected. An electroencephalogram confirmed seizure activity with main focus on the right side at the central, parietal, and occipital regions further supporting neuroanatomical localization. Additionally, subclinical paroxysmal activity was noted on the electroencephalogram. A ganglioglioma was identified in the right cerebrothalamic area, and other cranial parts of the brainstem based on immunohistochemical examination. To the authors' knowledge this is the first report of intracranial ganglioglioma in the horse. This intracranial neoplasia should be added to the possible causes of intracranial masses and seizures in horses.

Case summary

A 10-year-old Maine Coon cat was presented for acute onset seizures and cerebrothalamic signs. An intracranial mass, suspected to be a meningioma, was diagnosed on MRI and surgically excised. Histopathology appeared consistent with an atypical meningioma. However, following rapid regrowth of the neoplasm, the patient was humanely euthanized 3 months later. On post-mortem histopathology, the neoplasm was diagnosed as a grade III anaplastic gemistocytic astrocytoma.

Relevance and novel information

Gemistocytic astrocytomas are rare brain tumors in the feline patient. This case represents the first report of a feline grade III anaplastic gemistocytic astrocytoma in the cerebrum of a cat with surgical excision and recurrence. The challenging nature of ante-mortem diagnosis and the guarded prognosis, despite surgical intervention, are presented in this report.