Characterization and mode of inheritance of a paroxysmal dyskinesia in Chinook dogs

Background: Paroxysmal dyskinesias are episodes of abnormal, involuntary movement or muscle tone, distinguished from seizures by the character of the episode and lack of seizure activity on ictal EEG. Hypothesis: Paroxysmal dyskinesia is an inherited, autosomal recessive disorder in Chinook dogs. Animals: Families of Chinook dogs with paroxysmal dyskinesia. Methods: Pedigrees and medical histories were reviewed for 299 Chinook dogs. A family of 51 dogs was used for analysis. Episodes were classified as seizures, paroxysmal dyskinesia, or unknown, and segregation analysis was performed. Results: Paroxysmal dyskinesia was identified in 16 of 51 dogs and characterized by an inability to stand or ambulate, head tremors, and involuntary flexion of 1 or multiple limbs, without autonomic signs or loss of consciousness. Episode duration varied from minutes to an hour. Inter‐ictal EEGs recorded on 2 dogs with dyskinesia were normal. Three dogs with dyskinesia also had generalized tonic‐clonic seizures. One of 51 dogs had episodes of undetermined type. Phenotype was unknown for 6 of 51 dogs, and 28 dogs were unaffected. Segregation was consistent with an autosomal recessive trait. Conclusions and Clinical Importance: This movement disorder is prevalent in the Chinook breed, and consistent with a partially penetrant autosomal recessive or polygenic trait. Insufficient evidence exists for definitive localization; episodes may be of basal nuclear origin, but atypical seizures and muscle membrane disorders remain possible etiologies. The generalized seizures may be a variant phenotype of the same mutation that results in dyskinesia, or the 2 syndromes may be independent.     

Supplemental pollination-increasing jojoba (Simmondsia chinensis L. [schneider]) seed yields in the Arid Chaco environment

Jojoba (Simmondsia chinensis L. [Schneider]) is a wind-pollinated perennial shrub native to the Sonoran Desert. In recent years commercial plantations in Arizona and Catamarca, Argentina have dramatically decreased in size and number, going from 13,000 ha in the early 1980s to about 2,300 ha today. The main reason for this decrease is yields being lower than expected, with low pollination percentages considered the main source of the problem, although use of inferior genetic material has contributed to the problem. Artificial or supplemental pollination has been used successfully in other crops to increase yields, and it was thought that this could also be used for jojoba. A trial was carried out over two seasons in which pollen collected in Arizona, was mechanically applied to commercial fields in Catamarca. The first year yields were significantly (P < 0.05) greater in the fields in which pollen had been applied, than in the controls. The second year yields were not measured. Rather the number of capsules with fruit, aborts, and empty capsules were counted on a number of randomly selected branches. This technique gives a good estimate of yield, and the results showed that pollen application significantly (P < 0.05) increased expected yields. In conclusion, application of supplemental pollen increases jojoba yields and hence should be considered a viable option for commercial plantations. Additional work is required, however, to determine the correct application rate so as to minimize collection costs, and determine when application should take place to optimize efficacy.     

Finding the appropriate level of complexity for a simulation model: An example with a forest growth model

The topic of model complexity is fundamental to model developers and model users. In this study, we investigate how over- and under-fitting of a driving function in a simulation model influences the predictive ability of the model. Secondly, we investigate whether model selection approaches succeed in selecting driving functions with the best predictive ability. We address these issues through an example with the forest simulator SORTIE-ND. Utilizing maximum likelihood methods and individual tree growth data we parameterize five growth functions of increasing complexity. We then incorporate each growth function into the simulation model SORTIE-ND and test predicted growth against independent data. Compared to the independent data, the simplest and the most complex growth functions had the poorest predictive ability while functions of intermediate complexity had the best predictive ability. The poor predictive ability of the simplest model is caused by poor approximation of the system while the poor predictive ability of the most complex model is caused by biased parameter estimates. A growth function of intermediate complexity was the most parsimonious model where error due to approximation and error due to estimation were simultaneously minimized. The model selection criteria AIC and BIC were found to select complex functions that were over-fitted according to the independent data comparison. BIC was closer to choosing the model that minimized prediction error than AIC. In this example, BIC is the more appropriate model selection criterion. It is important that both model developers and models users remember that more complex models do not always result in better predictive models.     

Treatment of a Myasthenic Dog with Mycophenolate Mofetil

A ten‐year‐old, male castrated Springer Spaniel was presented for dysphagia, ptyalism, and regurgitation. Evidence of megaesophagus and mild aspiration pneumonia were apparent on thoracic radiographs. A diagnosis of focal acquired myasthenia gravis was suspected and subsequently confirmed with a positive serum acetylcholine (ACh) receptor antibody concentration (3.87 nM/L). A gastrostomy tube was placed shortly after presentation; food and drugs (including azathioprine) were administered through the tube. After transient improvement, the dog suddenly deteriorated clinically, experiencing frequent episodes of regurgitation and developing severe aspiration pneumonia. Mycophenolate mofetil (MMF), a novel immunosuppressive drug with relative specificity for lymphocytes, was instituted every twelve hours via the gastrostomy tube. Within four days of beginning MMF therapy, both clinical evidence of pharyngeal/esophageal dysfunction and radiographic evidence of megaesophagus had resolved. Initially, clinical side‐effects of combined MMF/AZA administration were not apparent, but the patient experienced several vomiting episodes during the third week of treatment. The vomiting resolved after decreasing the dose of both drugs. The patient made a full recovery, and a one‐month follow‐up ACh receptor antibody concentration was normal (0.26 nM/L). After one month of combination therapy, the patient was weaned off of AZA and maintained on MMF as the sole immunosuppressive drug. The dog was subsequently weaned off of MMF on two occasions. Mycophenolate mofetil was reinstituted after the first discontinuation due to the development of profound appendicular muscle weakness two days after stopping MMF; the weakness resolved within 24 hours of reinstituting MMF. A positive ACh receptor antibody concentration (0.89 nM/L) after the second MMF weaning prompted the second reinstitution of MMF. Two months following this second MMF reinstitution, the dog was again serologically negative (0.51 nM/L) for myasthenia gravis. At the time of last followup, the dog remained in clinical remission eight months after initial presentation. The use of MMF to treat acquired myasthenia gravis in dogs has not been reported previously. The literature concerning MMF and its potential use in treating patients with autoimmune diseases is discussed.     

A survey of malformed aborted bovine fetuses, stillbirths and nonviable neonates for abnormal karyotypes.

Postmortem examinations were performed on 30 morphologically abnormal aborted bovine fetuses, stillbirths and nonviable neonates. Fibroblasts from the pericardium were cultured for chromosome analysis. Karyotypes were successfully completed on 18 animals, of which three were trisomic, one was mosaic monosomic and one was chimeric. All aneuploid calves had multisystemic anomalies. Using chromosomal banding techniques, the abnormal karyotypes were determined to be: 61,XY,+27; 61,XX,+21; 61,XY,+?; 59,XY,-?/60,XY; and 60,XX/60,XY. Bacterial contamination or nonviability of tissues prevented the growth of fibroblasts in culture and cytogenetic analysis of the other 12 animals. It was estimated that 2.0% of all late gestation abortuses and stillbirths may have chromosomal abnormalities characterized by aneuploidy. The findings of this study suggest chromosomal abnormalities characterized by aneuploidy are a significant cause of multisystemic anomalies in aborted bovine fetuses and nonviable neonates.     

Chromosomal trisomy in an anormalous bovine fetus

This case report describes an anomalous male fetus of approximately six months gestation with abnormal karyotype containing an extra metacentric chromosome of medium size. The fetus had severe phenotypic abnormalities including anasarca, eye malformations, cardiac hypertrophy, pulmonary hypoplasia, adrenal dysplasia, and an umbilical hernia.     

Analysis of serum protein concentrations after severe thermal injury in a dog

Serial serum electrophoreses and routine serum protein assays were used to assess changes in serum protein concentrations after severe thermal injury in a dog. Electrophoretic patterns during the month of evaluation were consistent with protein-losing dermatopathy (thermal burn) and inflammatory dysproteinemias.     

Grass and legume seeding on a scarified coastal alluvial site in northwestern British Columbia: response of native non-crop vegetation and planted Sitka spruce (Picea sitchensis (Bong.) Carr.) seedlings

The success of various grass-legume mixtures in controlling competing vegetation, and their effect on subsequent survival and growth of Sitka spruce seedlings was studied on a coastal alluvial site in northwestern British Columbia. Mechanically scarified (bladed) strips were hand seeded to pure and combined mixtures of legumes, bunchgrasses, and sodforming grasses. An unseeded control (bladed but not seeded) was also established.Alsike clover (Trifolium hybridum L.) was the most successful legume species. Orchardgrass (Dactylis glomerata L.), big bluegrass (Poa ampla Merr.), and creeping red fescue (Festuca rubra L.) were the most successful grass species. Red alder (Alnus rubra Bong.) density and height were lower in legume-seeded treatments. Red elderberry (Sambucus racemosa L.) and salmonberry (Rubus spectabilis Pursh.) were effectively reduced by blading and have reestablished slowly. A combination of blading and early establishment of either sodforming grasses or bunchgrasses effectively decreased reinvasion by thimbleberry (Rubus parviflorus Nutt.).Growth of Sitka spruce was best in the unseeded control treatment or in the treatments with legumes but no sodforming grasses. Presence of sodforming grasses decreased both diameter and height growth. Sitka spruce diameter decreased with increasing red alder density. After 5 growing seasons, spruce has outgrown all competitors except red alder.