Anatomic description of the basivertebral nerve and meningeal branch of the spinal nerve in the dog.

PURPOSE: The existence of the basivertebral nerve and meningeal branch of the spinal nerve has not been proven in dogs to date. The objectives of this study are to 1) determine whether dogs have a meningeal branch of the spinal nerve (MBSN) and a basivertebral nerve (BVN) and to (2) describe anatomical characteristics of these two nerves. Authors also put forward a discussion on the possible clinical relevance of these findings. MATERIAL AND METHODS: Dissections were performed on six embalmed dogs at the Veterinary Faculty of Barcelona with the use of stereomicroscopy and microsurgery equipment. RESULTS: The MBSN (grossly) and BVN (grossly and histologically) were identified in the cervical, thoracic, and lumbar region in all dog specimens. In addition, other small fibers (suspected nerves) entering the vertebral body through small foramina close to the end plates were identified. Histological examination of the tissues confirmed the presence of nerve fibers (myelinated and unmyelinated) in suspected BVN samples. Results of the present study indicated that dogs have BVNs. Also, suspected nerve fibers were identified among the epidural fat, running from the intervertebral foramina, that likely represent the MBSN. CONCLUSION: These findings open up the discussion on extrapolation of treatment options employed in human medicine for "low back pain", such as BVN ablation, which is discussed in this article. Further anatomic and clinical studies of the innervation for the vertebral body, periosteum, vasculature, dorsal longitudinal ligament and anulus fibrosus are necessary to elucidate possible anatomical variants and breed differences as well as potential clinical (e.g., therapeutic) relevance.

Adult onset acquired myasthenia gravis in three Great Dane littermates.

Acquired canine myasthenia gravis is an autoimmune disease in which autoantibodies are directed against muscle postsynaptic nicotinic acetylcholine receptors. Three adult great dane littermates were evaluated over a four month time period for an acute onset of generalised neuromuscular signs. All three dogs had elevated serum acetylcholine receptor antibody titres, which were considered diagnostic for acquired myasthenia gravis. Identification of three littermates with acquired myasthenia gravis in a breed with a low relative risk of developing the disease suggests a familial and possibly a genetic predisposition to myasthenia gravis in this family of dogs.

Neuroendodermal cyst in the fourth ventricle of a dog.

CASE REPORT: We describe the MRI appearance and surgical outcome of a rare neuroendodermal cyst in the fourth ventricle of a German Shorthaired Pointer. The dog presented with uncoordinated gait and occasional falling that increased when she became excited. The MRI appearance is shown and the surgical treatment described. Recurrence occurred on two occasions and the dog was euthanased. CONCLUSION: Recurrence of these cysts is highly likely unless there is complete surgical resection.

Surgical removal of a choroid plexus oncocytoma in an adult cat.

An 11-year-old male castrated domestic shorthair cat presented with left central vestibular dysfunction. Magnetic resonance imaging of the brain revealed a large, extra-parenchymal, strongly contrast-enhancing mass at the level of the left cerebellopontine angle and compressing the cerebellum and brainstem. The mass was surgically excised via left rostral and sub-tentorial craniectomies and histopathology revealed an epithelial neoplasm composed of anastomosing cords of neoplastic cells that contained large amounts of finely granular hypereosinophilic cytoplasm and round nuclei. The cytoplasmic granules were variably positive with periodic acid-Schiff and modified Gomori trichrome. Immunohistochemical staining with anti-cytokeratin AE1/AE3 was diffusely positive. Electron microscopy revealed neoplastic cells that were full of electron-dense organelles consistent with mitochondria. This is the first case of a choroid plexus oncocytoma in the central nervous system of any domestic animal species and highlights the role of successful surgical intervention in extra-parenchymal neoplasia in the central nervous system.

Hemifacial Microsomia in a Cat.

A 7-month-old domestic medium hair cat presented with facial asymmetry affecting the bony and soft tissue structures of the right side of the head including the maxilla, nose, eye and pinna of the ear. Additionally, neurological dysfunction of the facial and vestibulocochlear nerves on the affected side was present. A congenital malformation affecting the first and second embryologic pharyngeal arches was suspected. This is the first case of hemifacial microsomia of likely congenital origin reported in a cat.

Hydrocephalus secondary to obstruction of the lateral apertures in two dogs.

BACKGROUND: Traditionally, hydrocephalus is divided into communicating or non-communicating (obstructive) based on the identification of a blockage of cerebrospinal fluid (CSF) flow through the ventricular system. Hydrocephalus ex vacuo refers to ventricular enlargement as a consequence of neuroparenchymal loss. Hydrocephalus related to obstruction of the lateral apertures of the fourth ventricles has rarely been described. CASE REPORT: The clinicopathologic findings in two dogs with hydrocephalus secondary to obstruction of the lateral apertures of the fourth ventricle are reported. Signs were associated with a caudal cervical spinal cord lesion in one dog and a caudal brain stem lesion in the other dog. Magnetic resonance imaging (MRI) disclosed dilation of the ventricular system, including the lateral recesses of the fourth ventricle. In one dog, postmortem ventriculography confirmed obstruction of the lateral apertures. Microscopic changes were identified in the choroid plexus in both dogs, yet a definitive cause of the obstructions was not identified. The MRI findings in both dogs are similar to membranous occlusion of the lateral and median apertures in human patients. CONCLUSION: MRI detection of dilation of the entire ventricular system in the absence of an identifiable cause should prompt consideration of an obstruction of the lateral apertures. In future cases, therapeutic interventions aimed at re-establishing CSF flow or ventriculoperitoneal catheterisation should be considered.

Clinical, magnetic resonance imaging, and histopathologic findings in 6 dogs with surgically resected extraparenchymal spinal cord hematomas.

BACKGROUND: Extraparenchymal spinal cord hematoma has been described in veterinary medicine in association with neoplasia, intervertebral disk disease, and snake envenomation. There are rare reports of spontaneous extraparenchymal spinal cord hematoma formation with no known cause in human medicine. Multiple cases of spontaneous extraparenchymal spinal cord hematoma have not been described previously in veterinary medicine. OBJECTIVES: To describe the signalment, clinical findings, magnetic resonance imaging (MRI) features, and surgical outcomes in histopathologically confirmed extraparenchymal spinal cord hematomas in dogs with no identified underlying etiology. ANIMALS: Six dogs had MRI of the spinal cord, decompressive spinal surgery, and histopathologic confirmation of extraparenchymal spinal cord hematoma not associated with an underlying cause. METHODS: Multi-institutional retrospective study. RESULTS: Six patients had spontaneous extraparenchymal spinal cord hematoma formation. MRI showed normal signal within the spinal cord parenchyma in all patients. All hematomas had T2-weighted hyperintensity and the majority (5/6) had no contrast enhancement. All dogs underwent surgical decompression and most patients (5/6) returned to normal or near normal neurologic function postoperatively. Follow-up of the patients (ranging between 921 and 1,446 days) showed no progression of neurologic clinical signs or any conditions associated with increased bleeding tendency. CONCLUSIONS AND CLINICAL IMPORTANCE: Before surgery and histopathology confirming extraparenchymal hematoma, the primary differential in most cases was neoplasia, based on the MRI findings. This retrospective study reminds clinicians of the importance of the combination of advanced imaging combined with histopathologic diagnosis. The prognosis for spontaneous spinal cord extraparenchymal hematoma with surgical decompression appears to be favorable in most cases.

Magnetic resonance imaging and computed tomography findings of Dyke-Davidoff-Masson-like syndrome in a cat.

CASE REPORT: A 3.5-year-old spayed female Domestic Shorthair cat was evaluated for new onset seizures and lateralising signs indicative of a lesion in the right prosencephalon. Magnetic resonance imaging and computed tomography of the head revealed hypoplasia of the right cerebral hemisphere and changes in the overlying cranium, including hyperostosis and expansion of the diploic space, resulting in an increased pneumatisation of the rostral bones of the cranium. A congenital injury to the cerebral hemisphere and secondary changes of the cranium in response to the decreased brain parenchyma was presumed. Similar changes have been previously recognised in human patients with unilateral anomalies of the cerebral hemispheres, termed Dyke-Davidoff-Masson syndrome (DDMS). CONCLUSION: The case presented is the first clinical and imaging description of a cat with a syndrome that closely resembles DDMS in humans. The description of the syndrome allows recognition of an additional differential for seizures in a young patient and informs the clinician of the imaging characteristics of the cranium seen with early loss of brain parenchyma.

Urinary excretion of taurine as a function of taurine intake: potential for estimating taurine bioavailability in the adult cat.

Urinary taurine excretion increases markedly when excess taurine is consumed. Experiments were designed to characterize this response in an attempt to develop an assay system for taurine bioavailability in common cat foods using an adult cat model. Initial studies investigated the time course of changes in urinary taurine excretion in response to alterations in taurine intake. The rate of urinary taurine excretion decreased rapidly when cats were switched from a casein diet supplemented with 0.2% crystalline taurine to a diet containing no supplemental taurine, reaching steady-state in 2 d. In contrast, urinary taurine excretion by cats switched from low to high taurine did not plateau until 6 to 7 d. Subsequently, cats (n = 18) were fed a casein diet containing graded levels of crystalline taurine (0, 0.025, 0.05, 0.10, 0.15 or 0.20%). After a 7-d adjustment period, urinary taurine excretion was quantified over a 5-d collection period and also by cystocentesis, and blood taurine levels were measured on d 6. Plasma taurine increased linearly (r = 0.88) as taurine intake increased, while whole-blood taurine increased asymptotically, reaching 95% of maximum concentration at a taurine intake of 93 mu mole/(kg body weight.d). The rate of urinary taurine excretion increased only slightly as taurine intakes increased to 96 mu mol/(kg body weight.d), but increased markedly (15-fold) thereafter. The same pattern was observed whether urinary taurine excretion was expressed as mu mole/(kg body weight.d) from total urine collection or as mu mole/g creatinine from cystocentesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and clinicopathologic features in 11 cats with Cuterebra larvae myiasis of the central nervous system.

The medical records of 11 cats with histopathologic findings consistent with central nervous system (CNS) Cuterebra larvae myiasis were retrospectively examined to determine if clinical features could identify this disorder antemortem. Young to middle-aged indoor-outdoor domestic shorthaired cats presenting with acute neurologic signs from July through September predominated. Many cats recently had clinical signs consistent with upper respiratory disease. Most cats presented for depression, lethargy, or seizures. Almost all cats had abnormal rectal temperatures, either hypethermia or hypothermia. Peripheral leukocytosis and eosinophilia were not characteristic of cats with CNS cuterebriasis. Cerebrospinal fluid analysis did not consistently disclose evidence of inflammation. Common neurologic deficits included blindness, abnormal mentation, and signs of unilateral prosencephalic disease. No specific clinical or clinicopathologic test was diagnostic for CNS cuterebriasis.

Late-onset cerebellar abiotrophy in a Labrador Retriever.

CASE REPORT: A 5-year-old female spayed Labrador Retriever was examined for a hindlimb gait abnormality. Initial neurological examination was consistent with vestibular dysfunction. Over the course of 1 year, signs progressed to reflect cerebellar ataxia, vertical nystagmus and delayed postural reactions in all limbs. At the initial examination, subjective evaluation of magnetic resonance imaging scan of the brain was considered normal. Repeat imaging at 1 year after initial examination revealed a reduction in the size of the cerebellum. Retrospectively, the size of the cerebellum on the initial MRI was small when assessed using an objective measurement algorithm. Postmortem histopathological evaluation of the brain showed diffuse degeneration of Purkinje cell neurones with secondary granule cell loss in the cerebellum, in addition to pigment inclusions in brainstem neurones. CONCLUSION: The clinical history and clinicopathological data are consistent with late-onset cerebellar abiotrophy, which has not previously been described in this breed.

Prevalence of effusion in the tympanic cavity in dogs with dysfunction of the trigeminal nerve: 18 cases (2004-2013).

BACKGROUND: Animals with disorders involving the trigeminal nerve or its nuclei in the brainstem can have effusion in the tympanic cavity ipsilateral to the side of the neurological deficits. The tensor veli palatini muscle (TVP), innervated by the mandibular branch of the trigeminal nerve, opens the pharyngeal orifice of the auditory tube. With denervation of the TVP, dysfunction of the auditory tube may occur, which could lead to effusion. HYPOTHESIS/OBJECTIVES: To determine the prevalence of effusion in the tympanic cavity in dogs with disorders involving the trigeminal nerve. ANIMALS: Eighteen client-owned dogs were evaluated retrospectively. METHODS: Retrospective study. RESULTS: Diagnostic imaging databases were searched for dogs having undergone magnetic resonance imaging (MRI) evaluation for signs referable to dysfunction of the trigeminal nerve. Signalment and neurological examination findings were recorded. The MRI study was evaluated for the presence or absence of effusion. MRI characteristics of the affected trigeminal nerve and the muscles of mastication were recorded. Based on the location of the trigeminal nerve lesion, dogs were divided into three categories: brainstem, trigeminal canal, or extracranial. Eighteen dogs met the inclusion criteria. Six of 18 dogs (33%) had effusion in the tympanic cavity ipsilateral to the affected trigeminal nerve. CONCLUSION AND CLINICAL IMPORTANCE: A substantial proportion of dogs with a lesion affecting the trigeminal nerve had effusion in the tympanic cavity. This finding likely represents denervation of the TVP muscle, which may have led to dysfunction of the auditory tube.

Brain abscess in a goat.

A young goat was presented with a left spastic hemiparesis and general proprioceptive ataxia with postural reaction deficits, a right head tilt and positional nystagmus. Seizure-like activity was elicited by rapid changes in the position of the animal's head. The neurological signs and quality of the seizure activity suggested a lesion involving the medulla and possibly the cerebellum. A focal lesion at the level of the left cerebellar peduncles could explain the left hemiparesis and right paradoxical vestibular signs. A large encapsulated abscess was found at the confluence of the left cerebellar peduncles. The morphology and staining characteristics of the organisms within the abscess were consistent with Corynebacterium pseudotuberculosis.

Urinary taurine excretion as a function of taurine intake in adult cats.

Experiments were designed to develop a urinary excretion model for the study of taurine status in adult cats. The time course of changes in urinary taurine excretion in response to alterations in dietary taurine was examined in Experiment 1. Urinary taurine excretion decreased rapidly when cats were switched from a casein diet supplemented with 2000 mg crystalline taurine/kg diet to a diet containing no supplemental taurine reaching a plateau in 2 d, but the cats required 7 d to reach a plateau when switched from the nonsupplemented diet to the 2000 mg taurine/kg diet. In Experiment 2, the casein diets contained graded levels of crystalline taurine (0, 250, 500, 1000, 1500 or 2000 mg/kg). After a 7-d adjustment period, urinary taurine excretion was quantified over 5 d, and blood taurine concentrations were measured on d 6. Plasma taurine concentration increased linearly (r = 0.88) as taurine intake increased, but whole-blood taurine increased asymptotically. Taurine intakes of greater than 96 mumol/(kg body wt.d) resulted in urinary excretion rates that were 15 times greater than those occurring below this break point. We suggest that urinary taurine excretion by cats fed taurine at levels above the break point has potential for estimating taurine bioavailability in intact meat-source proteins.

A modified bilateral transfrontal sinus approach to the canine frontal lobe and olfactory bulb: surgical technique and five cases.

Five adult dogs presented for an acute onset of seizure activity. Magnetic resonance imaging revealed lesions in the olfactory bulbs, frontal lobes of the cerebrum, or both. A modified bilateral transfrontal sinus craniotomy was performed on each patient. The goal of removing the lesion was to relieve clinical signs and to provide tissue for histopathological diagnosis. In each instance, excision of the lesion was possible using this approach. No postoperative complications were observed. The modified bilateral transfrontal sinus craniotomy provides excellent access to the canine olfactory bulbs and frontal lobes.