Alexander de Lahunta

Canine X-linked muscular dystrophy: An animal model of Duchenne muscular dystrophy: Clinical studies

The progression of clinical disease and serum creatine kinase (CK) levels in canine X-linked muscular dystrophy (CXMD) was studied in 7 dogs from birth to 12-14 months and in 18 dogs at varying intervals from birth to 8 weeks. One affected male was studied from age 3.5 to 6 years, and all pups were descendants of this dog. A lethal neonatal form was recognized in some pups. In the more typical form, clinical signs of stunting, weakness and gait abnormalities were evident by 6-9 weeks and were progressive, leading to marked muscle atrophy, fibrosis and contractures by 6 months. Serum CK levels were markedly elevated, such that affected pups could be identified by 1 week. CK values increased until 6-8 weeks, then plateaued at approx. 100 times normal. Affected females and beagle-cross dogs were less severely affected than large breed-cross dogs. In the 2 adult dogs with cardiac insufficiency CK levels had decreased to 5-15 times normal. These studies show that CXMD and Duchenne muscular dystrophy have striking phenotypic as well as genotypic similarities. In addition, these studies of CXMD suggest that in females and in smaller dogs the same genetic defect results in a less severe clinical disease.

Canine X-linked muscular dystrophy : morphologic lesions

Gross pathologic lesions and light microscopic and ultrastructural features of skeletal muscle lesions in canine X-linked muscular dystrophy (CXMD) were studied in dogs from 3 months to 6 years of age. Necrosis and regeneration were present at all ages, but were most prominent in the youngest dogs studied. Increased intracytoplasmic calcium, as evidenced by positive alizarin red S staining, was associated with fiber necrosis, but was also seen in small numbers of otherwise normal fibers. Progressive changes included development of severe fiber size variation, endomysial and perimysial fibrosis, prominent cytoplasmic disorganization, internalization of myonuclei, mitochondrial proliferation, mild fat infiltration, and alterations in the fiber-type pattern. The most consistent early ultrastructural changes were dilatation of the sarcoplasmic reticulum and focal subsarcolemmal areas of degeneration. Convincing sarcolemmal defects were not found. Z-band streaming was present at all ages, and Z-band duplication and nemaline rods were seen in older dogs. Evidence for abnormal regeneration was found in the oldest dog, and was associated with extensive fibrosis. These findings document the progression of lesions in CXMD, and illustrate the profound alterations in fiber organization and fiber type that may occur in late stages of dystrophin-deficient muscular dystrophy.

Evaluation of decision criteria for detection of spinal cord compression based on cervical myelography in horses: 38 cases (1981–2001)

REASONS FOR PERFORMING STUDY Different criteria have been described based on height reduction of the total myelographic contrast column and components of it as tests for compression of the spinal cord due to cervical stenotic myelopathy (CSM). Fifty percent height reduction of the dorsal myelographic column (DMC), <2 mm empiric height of the DMC and a 40% reduction of the ratio of stenosis calculated based on the height reduction of the entire dural diameter (DD) have been described as decision criteria for considering the test result positive. The reasons for selecting these decision criteria or their accuracies have rarely been reported. OBJECTIVES To evaluate the accuracy of diagnostic criteria based on reduced height of the total myelographic column and components of it for diagnosing extradural spinal cord compression using different decision criteria, and make recommendations for consistent myelographic interpretation in horses suspected of having CSM. METHODS Four measurements were obtained by 2 readers in a retrospective sample population of 38 horses in which both cervical myelography and histopathological examination of the cervical spinal cord were performed. The prevalence of CSM in the sample was 50%. At intervertebral sites, the minimum heights of the DD and DMC were measured. At intravertebral sites, the maximum heights of the entire DD and DMC were obtained. Percent height reductions of the DMC and DD were determined as the ratio of minimum intervertebral height to maximum intravertebral height within the next cranial vertebra. Histological examination was used as the gold standard for determining the actual site of spinal cord compression. Sensitivity and specificity for the diagnostic criteria were estimated at each site in neutral and flexed neck positions using several different decision criteria. CONCLUSIONS At C6-C7, in neutral or flexed neck position and using 20% reduction of DD, the test was highly sensitive and specific for CSM. At other sites, reduced height of the myelographic column generally was not accurate for diagnosing extradural spinal cord compression. Using 20% reduction of DD in neutral position at the mid-cervical sites, the test had only low sensitivity and high specificity. Flexion of the neck appeared to increase detection of spinal cord compression in the mid-cervical region, but also substantially increased the frequency of false-positive diagnoses. POTENTIAL RELEVANCE By using the reported sensitivity and specificity estimates, readers may decide on a decision criterion for diagnosis of extradural spinal cord compression due to CSM. However, in planning a surgical correction, it is difficult to define a decision criterion that combines acceptable sensitivity and specificity, especially at the mid-cervical sites.

Vitamin E deficiency and risk of equine motor neuron disease

BackgroundEquine motor neuron disease (EMND) is a spontaneous neurologic disorder of adult horses which results from the degeneration of motor neurons in the spinal cord and brain stem. Clinical manifestations, pathological findings, and epidemiologic attributes resemble those of human motor neuron disease (MND). As in MND the etiology of the disease is not known. We evaluated the predisposition role of vitamin E deficiency on the risk of EMND.MethodsEleven horses at risk of EMND were identified and enrolled in a field trial at different times. The horses were maintained on a diet deficient in vitamin E and monitored periodically for levels of antioxidants – α-tocopherols, vitamins A, C, β-carotene, glutathione peroxidase (GSH-Px), and erythrocytic superoxide dismutase (SOD1). In addition to the self-control another parallel control group was included. Survival analysis was used to assess the probability of developing EMND past a specific period of time.ResultsThere was large variability in the levels of vitamins A and C, β-carotene, GSH-Px, and SOD1. Plasma vitamin E levels dropped significantly over time. Ten horses developed EMND within 44 months of enrollment. The median time to develop EMND was 38.5 months. None of the controls developed EMND.ConclusionThe study elucidated the role of vitamin E deficiency on the risk of EMND. Reproducing this disease in a natural animal model for the first time will enable us to carry out studies to test specific hypotheses regarding the mechanism by which the disease occurs.

Ossification of the Atlas‐Axis Complex in the Dog*

Skeleton preparations of 200 Beagles of known age, ranging from embryos at 28 days of age to 10 year old adults were studied. Preparations of gross specimens were examined with the aid of Alizarin red staining, binocular dissection and histological sections. Ossification centers for the components of the atlas and axis were identified and followed to their fusion. The developmental ossification sequence for these bones is described and compared with that of other similar studies in other species.

Clinical Signs, Computed Tomographic Imaging, and Management of Chronic Otitis Media/Interna in Dairy Calves

A31⁄2-week-old Holstein heifer calf was presented to Cornell University Hospital for Animals (CUHA) with a 2-week history of intermittent fever, coughing, and decreased growth and a 1-week history of drooling and droopy ears. The calf had been treated with several antibiotics without marked improvement. On physical examination, the calf was depressed, underweight, bradycardic (heart rate 60 bpm) and febrile (103.48F, 39.78C). Clinical signs attributable to cranioventral pneumonia included bilateral mucopurulent nasal discharge, coughing, and abnormal bronchial tones. Intermittently, there were food particles in the nasal discharge, ptyalism, difficult prehension and mastication of food, and regurgitation of green material from both the nose and mouth. Neurologic examination revealed depression, bilateral facial nerve paresis (decreased lip, eyelid, and ear tone; absent palpebral or menace reflex), and bilateral vestibular disease (balance loss to either side, no head tilt, and loss of physiologic vestibular nystagmus). No abnormal nystagmus was observed, but the eyeballs did not show the physiologic vestibular eyedrop on head and neck extension. The gait was normal. The diagnosis of bilateral cranial nerve (CN) VII and VIII disease suggested bilateral otitis media/interna. Deep palpation of the base of the ears elicited a pain response and nonodorous otorrhea was present, indicating a component of otitis externa. Upper airway and esophageal endoscopy was consistent with dysphagia and disturbed esophageal motility and showed tracheal mucopus, nasopharyngeal collapse, dorsal displacement of the soft palate, and esophageal dilatation with few contractions. Thoracic radiography and transtracheal aspirate cytology (many degenerate neutrophils, few macrophages, large amounts of mucus, no bacteria) confirmed the presence of bronchopneumonia. The transtracheal aspirate yielded Arcanobacter pyogenes and Mycoplasma spp., but fluorescent antibody testing for common respiratory viruses was negative. CBC results were normal. Lumbosacral cerebrospinal fluid (CSF) had a slightly high nucleated cell count (9 nucleated cells/mL, normal ,5 cells/mL; total protein concentration 17 mg/dL, normal ,70 mg/dL). Lateral skull radiographs did not show abnormalities, but computed tomography (CT) imaging indicated that both tympanic bullae and the right petrous temporal bone were enlarged,

Incidence and Risk Factors of Equine Motor Neuron Disease: An Ambidirectional Study

We have conducted an ambidirectional study to estimate the incidence of equine motor neuron disease (EMND) in the northeastern US. The clinical and pathological features of EMND are similar to those described in human motor neuron disease. We have also collected data on all EMND cases reported in the US and described the geographic distribution of the disease. To identify factors associated with the risk of EMND, the authors assembled 163 control horses from the population in which cases were identified. The significance of association between the hypothesized factors and the risk of EMND was evaluated using the logistic regression analysis and the risk was estimated using the odds ratio. Seventy-eight horses in North America were diagnosed with EMND between the period of January 1985 and November 1993. Most of the cases were identified in the Northeast of the US and the incidence of EMND appears to be increasing in this area. Factors found to be significantly associated with EMND were breed and the age of the horse. Quarter horses were the only breed with a significantly higher risk of EMND (odds ratio = 2.3). The risk of EMND increased with age, reached a peak around 16 years of age and then declined. The sex of the horse was not associated with the risk of the disease.

Bilateral, hypertrophic neuritis of the brachial plexus in a cat: magnetic resonance imaging and pathological findings

A 9-year-old Burmese cat was presented for investigation of a subacute onset of bilateral forelimb paresis. Magnetic resonance imaging of the cervico-thoracic vertebral column and brachial plexus revealed a bilaterally symmetrical, severe and diffuse swelling of the spinal nerves forming the caudal part of the brachial plexus. Histopathology of the abnormal nerve roots, spinal nerves and brachial plexi showed inflammatory and marked proliferative changes with similar features to that of hypertrophic neuritis of man. Hypertrophic neuritis in man is a rare, tumor-like, chronic inflammatory peripheral nerve disorder of unknown origin most frequently involving the brachial plexus.

Association of oxidative stress with motor neuron disease in horses.

OBJECTIVE To investigate the influence of oxidative stress in terms of antioxidant capacity and lipid peroxidation on the probability of motor neuron disease (MND) in horses. ANIMALS 88 horses with MND (cases) and 49 controls. PROCEDURES Blood samples were collected from all horses enrolled, and RBCs and plasma were harvested. Activity of the enzyme erythrocytic superoxide dismutase 1 (SOD1) was determined in the RBCs. Plasma concentrations of α-tocopherols and β-carotenes and activity of glutathione peroxidase were also evaluated. Degree of lipid peroxidation was measured by determining plasma concentrations of lipid hydroperoxides. Differences were evaluated between horse groups. RESULTS Cases had lower erythrocyte SOD1 activity than did controls, but the difference was not significant. On the other hand, plasma vitamin E concentrations differed significantly between groups, with the cases having lower concentrations. Neither plasma vitamin A concentration nor glutathione peroxidase activity differed between groups; however, cases had significantly higher concentrations of lipid hydroperoxides (18.53μM) than did controls (12.35μM). CONCLUSIONS AND CLINICAL RELEVANCE Horses with MND differed from those without MND by having a lower plasma concentration of vitamin E and higher concentrations of lipid hydroperoxides. Results parallel the findings in humans with sporadic amyotrophic sclerosis and provide evidence supporting the involvement of oxidative stress in the 2 conditions.

The Role of Dietary Antioxidant Insufficiency on the Permeability of the Blood-Brain Barrier

Our previous studies implicated vitamin E deficiency as a risk factor for equine motor neuron disease, a possible model of human amyotrophic lateral sclerosis, and showed direct effects of this deficiency on brain vascular endothelium. To gain better understanding of the pathogenesis of equine motor neuron disease, we determined the effects of dietary antioxidant insufficiency and the resultant brain tissue oxidative stress on blood-brain barrier permeability. Rats (n = 40) were maintained on a diet deficient of vitamin E for 36 to 43 weeks; 40 controls were fed a normal diet. Permeability of the blood-brain barrier in the cerebral cortex was investigated using rhodamine B, and lipid peroxidation was measured as a marker for oxidative stress. Animals on the vitamin E-deficient diet showed less weight gain and had higher brain lipidperoxidation compared with the controls. Fluorometric studies demonstrated greater rhodamine B in the perivascular compartment and central nervous system parenchyma in rats on the deficient diet compared with controls. These results suggest that a deficiency in vitamin E increases brain tissue oxidative stress and impairs the integrity of the blood-brain barrier. These observations may have relevance to the pathogenesis of amyotrophic lateral sclerosis and other neurologic diseases.