Effect of anesthesia-associated hypotension on neurologic outcome in dogs undergoing hemilaminectomy because of acute, severe thoracolumbar intervertebral disk herniation: 56 cases (2007-2013).

OBJECTIVE To evaluate the effect of anesthesia-associated hypotension on final motor and urinary function in paraplegic dogs without nociception that underwent hemilaminectomy because of acute, severe thoracolumbar intervertebral disk herniation (IVDH). DESIGN Retrospective case series. ANIMALS 56 paraplegic dogs with acute thoracolumbar IVDH and absent nociception. PROCEDURES Medical records were reviewed, and signalment, history, anesthetic details, and results of serial neurologic assessments performed for at least 4 weeks after surgery were recorded. Motor function was retrospectively scored with a 5-point scale, and urinary function was scored with a 3-point scale. Hypotension was defined as MAP ≤ 60 mm Hg or SAP ≤ 80 mm Hg for at least 2 consecutive readings 5 minutes apart. Associations between hypotension and outcome were assessed by use of the Fisher exact test. RESULTS Thirty-three (59%) patients experienced hypotension during anesthesia. Thirty-four (61%) patients (20/33 with and 14/23 without hypotension) regained ambulation. Whether dogs regained motor or urinary function was not significantly associated with the occurrence of hypotension (P = 0.35 and P = 0.86, respectively), the duration of hypotension (P = 0.213 and P = 0.274), or the lowest blood pressure recorded (P = 0.556 and P = 0.699). CONCLUSIONS AND CLINICAL RELEVANCE For this group of dogs undergoing hemilaminectomy because of acute, severe thoracolumbar IVDH, anesthesia-associated hypotension was not significantly associated with whether dogs regained motor or urinary function after surgery. However, normotension should be the goal in all patients with spinal cord injuries, especially patients undergoing general anesthesia.

Diagnosis and Outcome of Periosteal Chondrosarcoma in Two Cats.

Two cats, both over 10 yr old, were presented for evaluation of non-painful bony proliferations on the appendicular skeleton. These proliferations were identifiable via palpation. Radiographs showed a smooth, proliferative bony lesion of the distal femur (case 1) and tarsus (case 2) with mild soft tissue swelling. Surgical debulking with incomplete resection was performed in each cat. Subsequent histopathology resulted in a diagnosis of periosteal chondrosarcoma (PC). Although both cats have experienced local recurrence, both are still alive more than 2.5 yr after mass debulking. Periosteal chondrosarcoma is a differential diagnosis in proliferative cortical bony lesions near an articular surface in older cats. Partial resection of these masses can lead to an excellent quality of life, and proper diagnosis can avoid amputation or even euthanasia.

Analgesic effect of intra-articularly administered morphine, dexmedetomidine, or a morphine-dexmedetomidine combination immediately following stifle joint surgery in dogs.

OBJECTIVE: To compare the analgesic effects of intra-articularly administered saline (0.9% NaCl) solution, morphine, dexmedetomidine, and a morphine-dexmedetomidine combination in dogs undergoing stifle joint surgery for cranial cruciate ligament rupture. DESIGN: Randomized, controlled, clinical trial. ANIMALS: 44 dogs with cranial cruciate ligament rupture that underwent tibial tuberosity advancement (TTA) or tibial plateau leveling osteotomy (TPLO). PROCEDURES: Dogs received intra-articular injections of saline solution (0.2 mL/kg [0.09 mL/lb]), morphine (0.1 mg/kg [0.045 mg/lb]), dexmedetomidine (2.5 µg/kg [1.14 µg/lb]), or a combination of morphine (0.1 mg/kg) and dexmedetomidine (2.5 µg/kg). Intra-articular injections of the stifle joint were performed after completion of the corrective osteotomy procedure, just prior to skin closure. Signs of pain were assessed every 2 hours thereafter on the basis of mean behavioral and objective pain scores. Dogs with pain scores exceeding predetermined thresholds were given hydromorphone (0.05 mg/kg [0.023 mg/lb], SC) as rescue analgesia. RESULTS: Time to rescue analgesia did not significantly differ between dogs that underwent TTA versus TPLO. No significant difference in time to rescue analgesia was found among dogs receiving intra-articular injections of dexmedetomidine (median, 6 hours; range, 2 to 10 hours), morphine (median, 7 hours; range, 4 to 10 hours), or saline solution (median, 5 hours; range, 4 to 10 hours). However, time to rescue analgesia for dogs receiving intra-articular injection of the morphine-dexmedetomidine combination (median, 10 hours; range, 6 to 14 hours) was significantly longer than the time to rescue analgesia for other treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Intra-articular administration of the morphine-dexmedetomidine combination provided longer-lasting postoperative analgesia, compared with either morphine or dexmedetomidine alone, in dogs undergoing TTA or TPLO.

Ependymal and periventricular magnetic resonance imaging changes in four dogs with central nervous system blastomycosis.

Rapid detection of central nervous system (CNS) involvement is important for dogs with blastomycosis, as this can affect antifungal drug selection and has been associated with an increased risk of death. Previous reports describing magnetic resonance imaging (MRI) characteristics of canine CNS blastomycosis primarily identified mass lesions. The purpose of this retrospective study was to determine whether other MRI characteristics of CNS blastomycosis may also occur. Medical records of the Purdue University Veterinary Teaching Hospital were searched and four dogs met inclusion criteria. Magnetic resonance imaging characteristics included periventricular edema, periventricular and meningeal contrast enhancement, and ventriculomegaly. Periventricular lesions most commonly involved the rostral horn of the lateral ventricles and the third ventricle. Increased meningeal contrast enhancement involved the cerebrum, thalamus, sella turcica, and brainstem. Findings indicated that, in addition to mass lesions, MRI characteristics of periventricular hyperintensity, contrast enhancement, and ventriculomegaly may also occur in dogs with CNS blastomycosis.

Clinical and MRI findings in three dogs with polycystic meningiomas.

One spayed female Labrador retriever and two castrated male golden retrievers were evaluated for chronic (i.e., ranging from 3 wk to 24 wk) neurologic signs localizable to the prosencephalon. Signs included seizures, circling, and behavior changes. MRI demonstrated extra-axial, contrast-enhancing, multiloculated, fluid-filled, cyst-like lesions with a mass effect, causing compression and displacement of brain parenchyma. Differential diagnoses included cystic neoplasm, abscess or other infectious cyst (e.g., alveolar hydatid cyst), or fluid-filled anomaly (e.g., arachnoid cyst). The cyst-like lesions were attached to the rostral falx cerebri in all cases. In addition, case 2 had a second polycystic mass at the caudal diencephalon. Surgical biopsy (case 3 with a single, rostral tumor via transfrontal craniectomy) and postmortem histology (in cases 1 and 2) confirmed polycystic meningiomas. Tumor types were transitional (cases 1 and 3) and fibrous (case 2), with positive immunohistochemical staining for vimentin. Case 3 was also positive for E-cadherin, s100, and CD34. In all cases, staining was predominantly negative for glial fibrillary acid protein and pancytokeratins, supporting a diagnosis of meningioma. This report describes the first cases of polycystic meningiomas in dogs. Polycystic meningiomas are a rare, but important, addition to the differential diagnoses for intracranial cyst-like lesions, significantly affecting planning for surgical resection and other therapeutic interventions.

Evaluation of minimally invasive excisional brain biopsy and intracranial brachytherapy catheter placement in dogs.

OBJECTIVE: To evaluate a technique for minimally invasive excisional brain biopsy and intracranial brachytherapy catheter placement in dogs. ANIMALS: 5 healthy adult female dogs. PROCEDURES: Computed tomographic guidance was used to plan a biopsy trajectory to a selected area of brain with reference to a localizer grid. The procedure was performed through a 1-cm skin incision and 6-mm burr hole by use of a 9-gauge biopsy device. Five cylindrical samples (3 to 4 mm in diameter and 7 to 12 mm in length) were removed over 5 cycles of the vacuum-assisted tissue excision system, leaving approximately a 2-cm³ resection cavity. A balloon-tipped intracranial brachytherapy catheter was placed through the burr hole into the resection cavity, expanded with saline (0.9% NaCl) solution, and explanted 7 days later. RESULTS: 4 of 5 dogs survived the procedure. The fifth died because of iatrogenic brain damage. Neurologic deficits were unilateral and focal. Twenty-four hours after surgery, all surviving dogs were ambulatory, 2 dogs exhibited ipsiversive circling, 4 had contralateral proprioceptive deficits, 3 had contralateral menace response deficits, 2 had a reduced contralateral response to noxious nasal stimulation, and 1 had dull mentation with intermittent horizontal nystagmus and ventrolateral strabismus. Neurologic status improved throughout the study period. Histologic quality of biopsy specimens was excellent. CONCLUSIONS AND CLINICAL RELEVANCE: This technique enabled histologic diagnosis from high-quality biopsy specimens obtained through a minimally invasive technique and has potential applications for multimodal treatment of deep brain tumors in dogs.

Effect of width of disk fenestration and a ventral slot on biomechanics of the canine C5-C6 vertebral motion unit.

OBJECTIVE: To investigate the effects of disk fenestration and ventral slot formation on vertebral motion unit (VMU) range of motion (ROM) and determine the effects of fenestration and ventral slot width on VMU ROM. SAMPLE POPULATION: C5-C6 VMUs from 10 skeletally mature canine cadavers. PROCEDURES: Specimens were assigned to 2 groups (5 specimens/group). Surgery was performed in which width of a fenestration and a ventral slot was 33% (group 1) or 50% (group 2) the width of the vertebral body. Flexion-extension, lateral bending, and axial torsion ROMs were measured during loading before surgery, after fenestration, and after ventral slot formation. Range of motion was compared within groups to determine effects of surgical procedure on stability and between groups to determine effects of width of fenestration and ventral slot on stability. RESULTS: For both groups, fenestration resulted in a significant increase in ROM during flexion-extension, compared with results for intact specimens. Ventral slot formation resulted in a significant increase in ROM during flexion-extension and lateral bending, compared with results for intact specimens. Ventral slot formation resulted in a significant increase in ROM only during flexion-extension, compared with results for fenestrated specimens. There were no significant differences in ROM of the intact, fenestrated, and ventral slot specimens between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these results suggests that fenestration and ventral slot procedures each affect the biomechanics of the C5-C6 VMU. Width of a fenestration or ventral slot up to 50% of the width of C5-C6 may be clinically acceptable.

Extraskeletal osteosarcoma associated with retained surgical sponge in a dog.

Retained surgical sponges are usually discovered in the abdominal cavity, sometimes years after the surgical procedure, and the typical reaction is formation of a foreign-body granuloma, often called gossypiboma or textiloma. In this instance, an extraskeletal osteosarcoma, associated with the granulomatous reaction to a retained surgical sponge adjacent to the stifle, was diagnosed in an 11-year-old Labrador Retriever 9 years after repair of a ruptured cranial cruciate ligament. Radiographic detection of linear foreign material in the soft tissue mass was the basis for a diagnosis of gossypiboma. The mass was surgically excised. Histologically, fibers consistent with those of cotton gauze were associated with the granulomatous inflammation and the osteosarcoma. Amputation or radiation therapy was declined; the dog was treated conservatively with doxycycline and deracoxib. Three months after surgical excision, the dog was euthanized because of local recurrence of the mass along with lameness and decreased appetite.