Novel MRI and CT compatible stereotactic brain biopsy system in dogs using patient-specific facemasks.

OBJECTIVE: The objective of this pilot study was to describe the application and first preliminary data of a novel MRI and CT compatible patient-specific facemask for stereotactic brain biopsy of intracranial lesions in dogs. METHODS: Five client-owned dogs presenting for neurological deficits consistent with forebrain disease were included in the study. All dogs had MRI findings consistent with an intracranial lesion. Using images obtained from either MRI or CT, a virtual three-dimensional model of each dog's face was generated. The contact surface of each dog's face was selected for facemask design and a target point for biopsy was chosen using specialised software and toolkits. A patient-specific facemask with an attached biopsy port with premeasured and preselected trajectory was then fabricated by a 3D printer. The facemasks were sterilised and used intraoperatively to obtain biopsy samples. Biopsy samples were submitted for both cytological and histopathological evaluation. RESULTS: The diagnostic yield based on specific histological diagnosis was 80%. The one case in which a histological diagnosis could not be confirmed had a cytological interpretation consistent with meningioma. No major complications were observed during or immediately after brain biopsy and all dogs were discharged from the hospital within 72 hours postprocedure. CLINICAL SIGNIFICANCE: In conclusion, patient-specific facemasks appear to be a safe and effective method of brain biopsy in dogs, with minimal complications observed.

Low-level laser therapy reduces time to ambulation in dogs after hemilaminectomy: a preliminary study.

OBJECTIVES: A prospective study to determine if low-level laser therapy and surgery for intervertebral disk herniation encourage ambulation faster than surgery alone. METHODS: Thirty-six dogs with acute paraparesis/paraplegia due to acute intervertebral disk herniation were evaluated and given a modified Frankel score. Dogs with scores 0 to 3 were included in the study. Dogs were assigned to the control group (1) or the laser treatment group (2) based on alternating order of presentation. All dogs underwent surgery for their herniated disk. Dogs in group 2 were treated postoperatively with low-level laser therapy daily for five days, or until they achieved a modified Frankel score of 4. A 5 × 200-mW 810-nm cluster array was used to deliver 25 W/cm(2) to the skin. All dogs were scored daily by the investigators using the modified Frankel scoring system. RESULTS: The time to achieve a modified Frankel score of 4 was significantly lower (P=0.0016) in the low-level laser therapy group (median 3.5 days) than the control group (median 14 days). CLINICAL SIGNIFICANCE: Low-level laser therapy in combination with surgery decreases the time to ambulation in dogs with T3-L3 myelopathy secondary to intervertebral disk herniation.

Quantitative analysis of chondroitin sulfate isomers in intervertebral disk chondrocyte culture using capillary electrophoresis.

Chondroitin sulfate (CS) isomers, 6-sulfate (CS6) and 4-sulfate (CS4), change their ratio to each other in cartilaginous tissues with aging. In this study, a quantitative measurement method of CS6 and CS4 was developed, using capillary electrophoresis (CE). Various buffer solutions, pH, and digestion times were studied, and the use of 0.1 M Tris-HCl at pH of 8.0 allowed the isolation of CS6 and CS4 from CS most efficiently when combined with chondrotinase ABC at a concentration of 1 mU/microg of the substrate during a 3 hr digestion period. Amounts of newly synthesized CS6 and CS4 in the intervertebral disk chondrocyte three-dimensional culture were quantified by this method after the proteoglycans were extracted by equilibrium density centrifugation.

Magnetic resonance imaging of spongy degeneration of the central nervous system in a Labrador Retriever.

A 7-month-old, neutered female Labrador Retriever was evaluated for tetraparesis and subtle cerebellar dysfunction. Clinical signs progressed over a period of 6 weeks to severe ataxia, hypermetria, intention tremors, and finally non-ambulatory tetraparesis. On magnetic resonance imaging of the brain there were large, bilaterally symmetrical, ovoid lesions in the region of the deep cerebellar nuclei that were hyperintense on T2-weighted and proton density images and hypointense on T1-weighted images. There were similar but smaller bilaterally symmetrical lesions present within the thalamus. Euthanasia was performed and lesions consistent with the previously described spongy degeneration of Labrador Retrievers were identified. This disease and its relation to similar human heritable leukodystrophies are discussed.

Magnetic resonance imaging of cerebral cortical necrosis (polioencephalomalacia) in a dog.

A 3-year-old neutered female mixed breed dog was examined because of severe, generalized seizure activity, tetraparesis, and encephalopathic signs. Cerebrospinal fluid (CSF) evaluation was unremarkable except for a mild increase in protein. Serum and CSF titers for infectious diseases were negative. Magnetic resonance (MR) imaging examination of the brain was performed and lesions were found within the cerebral gray matter of the temporal and parietal lobes. The lesions had increased signal intensity on T1, T2, and proton density-weighted images. There was mild inhomogeneous enhancement following intravenous contrast medium administration. Neurologic status improved and the seizures were well controlled, but the dog never regained normal mentation and euthanasia was performed 10 weeks after initial evaluation. At necropsy, severe cerebral cortical necrosis was found in the regions corresponding to the lesions seen on MR imaging examination. Large numbers of fat-containing macrophages (gitter cells) were found within these areas, and are thought to be responsible for the characteristic hyperintensity seen on the MR images.

Canine intracranial epidermoid cyst.

A 7-year-old intact male pitbull presented with a 2-month history of progressive dysequilibrium. Cerebrospinal fluid analysis was indicative of a central inflammatory or neoplastic disorder. A cerebellar cystic structure was identified on magnetic resonance imaging which was found to be an epidermoid cyst on histopathology.

Secondary hypoadrenocorticism associated with craniocerebral trauma in a dog.

An 11-month-old, neutered female miniature schnauzer presented with a severe head injury. The dog was treated for the acute effects of craniocerebral trauma and was hospitalized for just over a week. Several weeks later, she became weak and lethargic. A diagnosis of hypoadrenocorticism was confirmed with an adrenocorticotropin hormone (ACTH) stimulation test. An endogenous ACTH assay confirmed secondary hypoadrenocorticism. The dog was tested for hypopituitarism with canine thyroid-stimulating hormone and thyroxine serum assays and an insulin-like growth factor assay. These tests could not confirm panhypopituitarism in this dog. The hypoadrenocorticism was treated with prednisone, and the dog remains controlled adequately three years later.

Vertebral physitis with epiphyseal sequestration and a portosystemic shunt in a Pekingese dog.

Vertebral physitis with bone sequestration and a portosystemic shunt were diagnosed in an 18-month-old female Pekingese dog. The latter was determined by the presence of low blood urea nitrogen, elevated serum bile acids, microhepatica and an increased portosystemic shunt fraction. It was managed with a home-cooked low protein diet. Vertebral physitis and bone sequestration was diagnosed by the presence of thoracolumbar hyperaesthesia, radiographic and scintigraphic changes, isolation of Staphylococcus intermedius from blood and the third lumbar vertebra, and histopathological examination of a surgical biopsy. A partial sequestrectomy was performed and a six-month course of amoxycillin-clavulanate was prescribed. The dog was pain-free and showed partial resolution of the radiographic signs four months after the discontinuation of antibiotics.

Pheochromocytoma in the vertebral canal of two dogs.

Pheochromocytomas are uncommon tumors arising from the adrenal gland, which have potential for aggressive local spread. The diagnosis is extremely challenging, particularly when classical endocrine signs are absent. This paper presents two canine cases of pheochromocytoma in the vertebral canal and illustrates the potential for detection of the tumor by abdominal ultrasonography.

Degenerative myelopathy.

DM in the German Shepherd is an immune-related disorder whose clinical signs are explained by a widespread degeneration of the white matter pathways in the thoracolumbar spinal cord. Therapy includes exercise, vitamin supplementation, and EACA medication. Avoiding unnecessary surgical procedures is also important to preclude permanent deterioration that can result following surgery in DM patients. In dogs other than German Shepherds, other identifiable causes should be treated. Additional confirmation of the diagnosis of DM may be assisted by performing cell-mediated immune studies or other serodiagnostic tests as they become available.

A redox-based system that enhances delivery of estradiol to the brain: pharmacokinetic evaluation in the dog.

The pharmacokinetics of a dihydropyridine-pyridinium salt-type chemical delivery system (CDS) for brain-targeted delivery of estradiol (E2) were examined in dogs. Parameters evaluated in vitro included stability in buffers and biological fluids and plasma protein binding. In vivo studies examined drug and metabolite concentrations in plasma, urine, and cerebrospinal fluid as well as in selected brain regions. The administered lipophilic E2-CDS disappeared very quickly from plasma and was not detected in urine. The oxidized drug form, E2-Q+, was excreted unchanged or as a conjugate in the urine for as long as 2 weeks. Plasma levels were below assay detection limits at later times. Pharmacokinetic analysis of urine E2-Q+ levels allowed estimation of a half-life of 2.2 days. Amounts of E2-Q+ excreted into the urine were proportional to the dose but averaged only 13.9% of the dose, indicating that other routes of excretion must be considered. CSF levels were below the limit of detection for both E2-CDS and E2-Q+, however, brain tissue concentrations of E2-Q+ were similar in several brain regions of individual animals examined 1 or 3 days after drug dosing.

Plasma and erythrocyte cholinesterase values for the common long-nosed armadillo, Dasypus novemcinctus.

Plasma and erythrocyte cholinesterase activities were determined for 40 free-living and 12 captive common long-nosed armadillos (Dasypus novemcinctus) in order to establish normal values for monitoring pesticide exposure. Plasma cholinesterase activity ranged from 105 to 549 U/liter with no sexual or seasonal differences. Plasma values from captive animals were significantly lower than those from wild armadillos. Erythrocyte cholinesterase activity ranged from 2,915 to 15,126 U/liter with no differences detected between captive and wild animals or between sexes. However, erythrocyte cholinesterase values varied seasonally. Erythrocyte and plasma cholinesterase activities were not significantly correlated. Packed cell volume ranged from 24 to 51% and did not vary significantly between captive and wild samples, between sexes or among seasons. However, both whole blood and erythrocyte cholinesterase activities showed significant negative correlations with packed cell volume. Controlled experiments are needed to find the factors responsible for the statistically significant difference between plasma cholinesterase activities of captive and wild armadillos. The seasonal variation in erythrocyte cholinesterase activity and the negative correlation between erythrocyte cholinesterase activity and packed cell volume can be explained by an hypothesis that relates the variation in erythrocyte cholinesterase activity to variation in erythrocyte turnover rate. Future work should involve experiments to test this hypothesis.

Distracted cervical spinal fusion for management of caudal cervical spondylomyelopathy in large-breed dogs.

Using an autogenous bone graft (obtained from the iliac crest), 4-mm cancellous bone screws, and polymethylmethacrylate, a distracted cervical spinal fusion technique was performed on 10 dogs with myelographic evidence of caudal cervical spondylomyelopathy. All dogs had evidence of dynamic soft tissue spinal cord compression, as indicated by flexion, extension, and traction myelographic views. Of the 10 dogs, 4 previously had undergone surgery by use of ventral slot or cervical disk fenestration techniques, and their neurologic status had deteriorated after the original surgery. Preoperative neurologic status of the 10 dogs included nonambulatory tetraparesis (n = 5), severe ataxia with conscious proprioceptive deficits (n = 2), and mild ambulatory ataxia with conscious proprioceptive deficits (n = 3). Five dogs had signs of various degrees of cervical pain. Clinical improvement was observed in 8 of 10 dogs--either improved neurologic status or elimination of cervical pain. Implant loosening developed in 3 dogs; 2 of them were euthanatized because of lack of neurologic improvement. Radiographic evidence of bony cervical fusion was observed during a 9- to 24-week period in 6 of the 8 surviving dogs. The distracted cervical fusion technique appears to be a valid surgical procedure to manage cervical spondylomyelopathy in those dogs in which the lesions are limited to one cervical intervertebral disk space.

Progressive myotonia in foals resembling human dystrophia myotonica.

A severe and progressive neuromuscular disorder accompanied by clinical, electrophysiological, and pathological features resembling human dystrophia myotonica was observed in three foals. This disorder was apparent as early as 1 month of age and involved progressive skeletal muscle dysfunction, initially characterized by proximal muscle hypertrophy and hypertonicity with subsequent muscle stiffness, weakness, and atrophy. Multisystem involvement was manifested in one case by testicular hypoplasia, early cataract formation, and borderline glucose intolerance. Prolonged dimpling of these large rear-limb muscles was elicited by percussion. Myotonic discharges were identified by electromyography. Percussion dimpling and the typical myotonic discharges persisted after neuromuscular blockade. Distinctive histologic muscle changes included ring fibers, sarcoplasmic mass formation, variation in fiber diameter size, and internally positioned nuclei.

Heartworm disease manifested by encephalomyelitis and myositis in a dog.

A 2-year-old Boston Terrier was referred because of depression and hindlimb and tail paresis. Clinical examination and serum biochemical analysis resulted in a diagnosis of encephalomyelitis and myositis. Results of testing for Dirofilaria immitis were positive. Gross and histologic examination revealed an aberrant adult heartworm infection resulting in thrombosis of the femoral artery and multiple muscular branches, with subsequent muscle necrosis and inflammation in one hindlimb. Additionally, an unusual larval-tissue interaction to microfilariae yielded a multifocal encephalomyelitis in the brain and spinal cord.

Interaction between canine platelets and adult heartworms: platelet recognition of heartworm surfaces.

An interaction between blood platelets and adult heartworms was examined in vitro. Surfaces of glutaraldehyde-fixed heartworms, which were taken from infected dogs washed, and incubated in platelet-rich plasma (PRP), were evaluated by scanning electron microscopy. Adherence of platelets to heartworms occurred only with PRP from infected dogs. Aggregation to epinephrine and adenosine diphosphate of PRP incubated with heartworms was monitored. Seemingly, platelet activation to heartworm membranes occurs in dogs with heartworm disease. The increased platelet reactivity was also observed in dogs with occult heartworm disease, indicating that the presence of circulating microfilaria was not important for this process. The ability to transfer the reactivity to heartworm-negative platelets by suspending them in heartworm-positive plasma indicated that this reactivity resided in the plasma. The processes leading to platelet activation may be responsible for the platelet-associated vascular disorders of canine heartworm disease.

Rostral hypothalamic microinfusions of 5,7 dihydroxytryptamine produce anatomically and neurochemically selective depletions of hippocampal serotonin and increase the influence of estrogen and food deprivation on locomotor activity.

Ovariectomized Long-Evans rats received bilateral rostral hypothalamic infusions of 5,7-dihydroxytryptamine (5,7-DHT). Neurochemical determination of catecholamines (CA) and indoleamines in the hippocampus, hypothalamus and mesencephalon revealed that 5,7-DHT infusions had no effect on CA content in these areas nor in mesencephalic serotonin or 5-hydroxyindoleacetic acid (5-HIAA). However, the neurotoxin produced significant decreases in hippocampal serotonin and 5-HIAA. Serotonin-depleted animals exhibited an increase in both spontaneous and estradiol-induced wheel running. In addition it was found that serotonin-depleted animals exhibit an enhanced activity response to starvation. Because estrogen is thought to decrease serotonergic transmission, the enhanced activity response to estrogen may be secondary to an estrogen-related exaggeration of the 5,7-DHT-induced serotonin depletion. The increased activity effect of starvation may indicate that serotonin-depleted animals do not effectively mobilize energy stored as lipid.

Failure of superoxide dismutase to alter equine arachidonic acid-induced platelet aggregation, in vitro or ex vivo.

Superoxide dismutase (SOD), a free radical scavenger with anti-inflammatory activity, was administered IM to horses. Ex vivo platelet aggregation in response to arachidonic acid was monitored to determine whether exogenous SOD altered equine platelet prostaglandin metabolism. Preparations of platelet-rich plasma obtained before SOD administration were incubated with different concentrations of SOD and were aggregated with arachidonic acid. Superoxide dismutase did not exert a demonstrable effect, either ex vivo or in vitro. Aspirin abolished arachidonic acid-induced platelet aggregation in vitro. This indicates that SOD (in the resting state) does not exert an effect on platelet-derived free radicals that could alter the arachidonic acid pathway of equine platelets, that equine platelets do not release free radicals, or that equine platelets are insensitive to the products formed from free radicals by SOD.