Using a three-dimensional-printed device with the patient's maxillary dental impression allows to perform minimally invasive brain biopsies in dogs and cats: a preliminary study.

OBJECTIVE: To develop an innovative process for stereotactic brain biopsies in dogs and cats that would provide a definitive diagnosis and optimize the management of patients with brain lesions. ANIMALS: 4 dogs and 1 cat diagnosed with 1 or more brain lesion(s) underwent brain biopsies between March 24, 2023, and October 25, 2023. METHODS: Based on trajectories selected on images of MRI and CT scan performed on each patient, a computerized software program was used to design a 3-D-printed patient-specific device with maxillary dental impression located on a baseplate to secure the patient's head and with insertion ports for the biopsy instrumentations located on a C-arm. As proof of concept, the device was successfully used in 2 cadavers before being used on clinical patients. All biopsy samples were submitted for histopathological examination. RESULTS: Histological diagnosis was obtained in 80% (4/5) of the cases (choroid plexus tumor, astrocytoma, meningioma, and chronic meningoencephalitis of unknown origin). In 1 patient, the results of biopsy were nondiagnostic; postmortem diagnosis was consistent with a low-grade oligodendroglioma. All the patients were discharged within 24 hours after the procedure without complications. This novel stereotactic system allows the surgeon to perform safe, easy-to-use, inexpensive, and minimally invasive precise brain biopsies in dogs and cats, without complications. CLINICAL RELEVANCE: This unique technique could be applied to any size and type of skull and for any type of brain lesions and would provide diagnostic information that would be valuable for future treatment planning and prognosis.

Demyelinating polyneuropathy with focally folded myelin sheaths in a family of Miniature Schnauzer dogs.

A spontaneous demyelinating polyneuropathy in two young Miniature Schnauzer dogs was characterized clinically, electrophysiologically and histopathologically. Both dogs were related and a third dog, belonging to the same family, had similar clinical signs. On presentation, clinical signs were restricted to respiratory dysfunction. Electrophysiological tests showed a dramatic decrease in both motor and sensory nerve conduction velocities. Microscopic examination of peripheral nerve biopsies (light and electron microscopy, teased nerve fibers), showed that this neuropathy was characterized by segmental demyelination and focally folded myelin sheaths. Various clinical syndromes associated with tomacula or focal thickening of the myelin sheath of the peripheral nerves have been described in humans and shown to be caused by gene mutations affecting the myelin proteins, such as the hereditary neuropathy with liability to pressure palsies or the demyelinating forms of Charcot-Marie-Tooth disease. In animals, a tomaculous neuropathy has been reported in cattle and chickens but not in carnivores. Here we report a demyelinating peripheral neuropathy with tomacula in two Miniature Schnauzer dogs.