Spina bifida with associated malformations of the central nervous system in Dorper-cross sheep

Abstract

CASE HISTORY: In 2008, six lambs within a flock of Dorpercross sheep were born with musculoskeletal and neurological disease. Clinical signs included hindlimb weakness, and urinary incontinence.

CLINICAL FINDINGS: All lambs had focal, inverted areas of alopecic skin over the caudal sacrum, and short, often kinked tails. Four affected lambs were subject to euthanasia, and necropsied. On gross examination, the arches of sacral vertebrae were absent, and spinal nerves and meninges were adherent to the overlying subcutis. Other gross lesions included narrow, elongated skulls, herniation of the occipital lobes into the caudal fossas, hydrocephalus, and syringomyelia. One lamb had coning of the cerebellar vermis, but cerebellar herniation through the foramen magnum was not identified.

DIAGNOSIS: Spina bifida, with associated malformations of the central nervous system.

CLINICAL RELEVANCE: Examination of breeding records suggested either an autosomal recessive or partially penetrant autosomal dominant pattern of inheritance. Because of the associated tail lesions it is proposed that the pathogenesis of this syndrome involves a defect in development of the tail bud (secondary neurulation), that tethering of the spinal cord resulted in the clinical signs, and abnormal pressure of the cerebral spinal fluid resulted in the defects in the skull and brain.     

Successful Treatment for Subinvolution of Placental Sites in the Bitch with Low Oral Doses of Progestagen

Subinvolution of placental sites (SIPS) is the major cause of persistent sanguineous vaginal discharge after parturition in the bitch. Spontaneous remission is common but may take several months, and hence, medical therapy to end the discharge is often requested. In this retrospective study, we evaluated the effect of treatment for SIPS with low oral doses of a progestagen. Nine bitches with SIPS, but otherwise clinically healthy, were found in the computer database of the Department of Clinical Sciences of Companion Animals. Seven of these bitches were treated with low oral doses of a progestagen (megestrol acetate, 0.1 mg/kg body weight (bw) once daily for the 1st week, then 0.05 mg/kg bw once daily for the 2nd week). The other two bitches were untreated. Treatment results were evaluated by a telephone questionnaire. Progestagen treatment was successful in all of the treated dogs; sanguineous vaginal discharge stopped within the treatment period. One of the two untreated dogs remained symptomatic until the next oestrus, approximately 120 days after parturition, and the other remained symptomatic until 6 weeks before the start of the next pro‐oestrus, 270 days after parturition. No side effects of the progestagen treatment were observed. Subsequent gestations, parturitions and puerperal periods of 5 mated bitches were uneventful. One bitch did not become pregnant after mating. In conclusion, the results of this study indicate that oral administration of low doses of progestagen for 2 weeks is effective in stopping persistent sanguineous vaginal discharge in bitches with SIPS, with neither side effects nor reduced subsequent fertility.     

Determining the bioavailability of contaminants and assessing the quality of sediments

Background, Aims and Scope  Our study determined the role of light, aeration, grain size, amount of sediments and of water, density of animals and presence of additional food on the movement of Ilyanassa obsoleta. Spiked relative to reference sediments were also tested for avoidance or preference by the mud snails. Our goal was to develop exposure conditions to be used in future assessment studies of the environmental quality of sediments inhabited by mud snails. The behavioural response of the snails towards different concentrations of contaminated Halifax Harbour sediments placed in one half of a tank relative to reference sediments in the other half is examined in Part 2 and a chemical link investigated. Methods  Animals were exposed in 7 L aquaria at 12°C to their native sediments placed in one or two halves of a tank and the effect due to the presence of a light source, air bubbles, sediment grain size, added algae examined relative to the snails’ behaviour. Preference or avoidance of one half of a tank relative to the second half, the immersed or dry glass surface represented the various media to be chosen by snails. After choosing the optimum set up, exposures were performed in triplicate, under slightly differing initial placement of the snails to compare means and variability in the results. Three specific biogenic chemicals, cholesterol, coprostanol and a fatty acid methyl ester (FAME) were spiked at 0.002, 0.01, 0.05, 0.25 and 1.2 mg/g, dry weight of sediment. A hexane, dichloromethane and methanol extract of harbour sediment were also spiked in reference sediments. In all cases, the location of the snails was recorded over a period extending up to 96 hrs. Results  Twenty snails exposed during a 72 hrs period in commercial 7 L tanks containing 50 g of sediments (wet weight) in the bottom half of a tank filled half way with seawater represented the chosen conditions to test the avoidance/preference behaviour of snails for part of a tank. The presence of additional food on sediments attracted snails within 24 hrs of exposure. Discussion  A general lack of preference was indicated in exposures to three biologically derived compounds spiked in reference sediments, i.e. a C-18 FAME, cholesterol and coprostanol. The repelling properties of a harbour sediment extract pointed to a role for non polar chemicals. Conclusions  It is proposed that behaviour reflects a balance between the repelling effects of contaminants and the attractive value of food. The present study provides a robust green assessment tool that is easy to set up to assess the quality of sediments. Recommendations and Perspectives  The interpretation of field observations regarding the abundance of animals during environmental assessments must consider both nutritional and toxicological causes. Additional laboratory exposures are needed to determine which chemicals play a role in the field.     

Flow cytometric immunophenotype of canine lymph node aspirates

Increasing availability of reagents able to distinguish subtypes of lymphocytes and other leukocytes has enabled greater understanding of lymphocyte biology and pathology in the dog. Lymphocytes in circulation most commonly are subjected to immunophenotypic assessment by flow cytometry, but needle aspirates of lymph nodes can be similarly suitable for immunophenotypic examination. In this investigation, the feasibility of immunophenotyping samples obtained by needle aspiration of lymph nodes from 32 dogs with no physical abnormalities and 6 dogs with lymphoma was determined. In addition, samples from 6 dogs were stored overnight at 4 degrees C and reanalyzed 24 hours later. For each sample, stained smear preparations were examined microscopically for lymphocyte morphology, neoplasia, and the presence of inflammatory cells. Expression of antigens on a corresponding sample of aspirated cells was determined by flow cytometric detection of antibody binding on a minimum of 10,000 events. The distribution of data was determined with Anderson-Darling tests, and reference intervals incorporating the central 95% of values were established. Adequate samples were obtained from 30 of 32 clinically normal dogs. Immunophenotypic results after 24 hours of storage were consistent with those obtained immediately after sampling. Reference intervals for lymphocyte subsets from normal dog lymph nodes were similar to the proportions of CD3+, CD4+, CD8+, and CD21+ lymphocytes found in blood. Aspirates of enlarged lymph nodes from dogs with lymphoma were readily classified by this technique. Aspiration of lymph nodes from dogs for comprehensive analysis by flow cytometry is feasible and applicable to immunophenotyping of lymphoma.     

Evaluation of the Karras Spermdensimeter in Relation to the Neubauer Counting Chamber for Sperm Concentration Measurement in Boar Semen

The correct measurement of spermatic concentration in boar semen is one of the basic tasks routinely performed at the Swine Artificial Insemination Center (CIAS). This article explains two experiments whose objectives were: Experiment 1: This trial had two objectives: (1) to evaluate the precision of the spermdensimeter (SPM) with relation to the Neubauer count chamber (CN) which is considered the standard technique in the field and (2) to correct the scale on the SPM table. Experiment 2: This trial also had two objectives: (1) to evaluate the time and repetitions required in the SPM and (2) to compare the SPM adjusted table produced in Expt 1 with the SPM standard table. The methods in Expt 1 were used to measure total spermatic concentration in 141 boar ejaculates. The average spermatic concentrations (10(6) spermatozoids/ml) and average dose number were 229.1 and 22.6 for CN, and 283.6 and 28.0 for SPM. These results indicate that the SPM has a tendency to overestimate spermatic concentration with relation to the CN. The SPM produced a smaller coefficient of variation and needed lesser examination time than the CN (p < 0.05). The SPM adjusted table created in Expt 1 produced similar results as the SPM and CN standard tables (2.96 billion live spermatozoids/dose vs 2.36 billion live spermatozoids/dose). Incorporation and evaluation of supplemental data from other CIAS regarding the use of the SPM adjusted table in the field entitled 'Adjusted Table for Karras Spermdensimeter LPS-FMVZ-USP' would be valuable to prove its efficiency.     

Anoestrus in the Dog: a Fascinating Story

In the bitch, progression from early to late anoestrus is characterized by a higher amplitude and a larger number of gonadotrophin-releasing hormone (GnRH) pulses generated by the hypothalamus, an increase in the sensitivity of the pituitary to GnRH, and an increase in ovarian responsiveness to gonadotrophins. An increase in basal plasma follicle-stimulating hormone (FSH) concentration is a critical event required for initiation of folliculogenesis. A period of increased luteinizing hormone pulsatility has been reported shortly before the onset of pro-oestrus. Apart from these changes in the hypothalamic-pituitary-ovarian axis, there is also involvement of dopaminergic influences in the initiation of a new follicular phase in the bitch. Administration of the dopamine-agonists bromocriptine and cabergoline shortens the anoestrus and is associated with a decrease in the plasma prolactin concentration, suggesting that the shortened anoestrus is the result of suppression of prolactin secretion. Yet, the anoestrus is not shortened in bitches treated with metergoline, a drug, which in a low dosage lowers the plasma prolactin concentration via a serotonin-antagonistic pathway. In addition, under physiological conditions low plasma prolactin concentrations are found during the entire anoestrus. Furthermore, a low dosage of bromocriptine, insufficient to cause a decrease in the plasma prolactin concentration, prematurely induces folliculogenesis. These observations indicate that not the decrease in the plasma prolactin concentration, but another dopamine-agonistic influence plays a critical role in the transition to a new follicular phase. The dopamine-agonist induced shortening of the anoestrus is associated with a rapid rise in the basal plasma FSH concentration, similar to what is observed during the physiological late anoestrus. This observation underlines the importance of an increase in the circulating plasma FSH concentration in the initiation of folliculogenesis in the bitch.     

Molecular evidence supporting Ehrlichia canis-like infection in cats

Currently, the pathogenic role of Ehrlichia canis in cats has been proposed predominantly on the basis of the serologic evidence of natural infection and the infrequent detection of morulae-like structures within the cytoplasm of leukocytes in cats. The purpose of this report was to provide molecular evidence supporting E. canis-like infection in 3 cats that had clinical manifestations consistent with canine ehrlichiosis but lacked antibodies to E. canis antigens. Serum from all 3 cats contained antinuclear antibodies (ANAs). The predominant disease manifestation was polyarthritis in 1 cat and bone marrow hypoplasia or dysplasia. accompanied by pancytopenia or anemia and thrombocytopenia, in 1 cat each. The alignment of E. canis partial 16S ribosomal DNA (rDNA: 382 nucleotide positions), amplified from EDTA blood samples from each cat, was identical to each other and was identical to a canine isolate of E. canis (GenBank accession number AF373613). In 1 cat, concurrent treatment with corticosteroids may have interfered with the therapeutic effectiveness of doxycycline for the elimination of E. canis-like infection. To further define the spectrum of ehrlichiosis in cats, polymerase chain reaction (PCR) testing may be necessary until serologic testing is thoroughly validated in experimentally or naturally infected cats. In addition, until E. canis has been isolated from cats and several tissue culture isolates are available from disparate geographic regions for detailed comparative genetic study, the molecular evidence presented in this study supporting E. canis-like infection in cats must be interpreted with caution.     

Resurgence of leptospirosis in dogs in Ontario: recent findings

A marked increase in leptospirosis in dogs was observed in 2000, part of an increasing trend observed in previous years in Ontario. The highest frequency of seropositive cases occurred from September to December 2000, with the peak in November. Large breed dogs were particularly affected. Clinical and clinicopathological data for 31 dogs admitted between 1998 and 2000 to the Ontario Veterinary College Veterinary Teaching Hospital were analyzed. Major clinical presenting features were acute onset of anorexia, depression, fever, and vomiting. Ninety percent of dogs, on admission, showed biochemical evidence of injury to several organs, notably combinations in the order of kidney, muscle, pancreas, and liver. Almost all dogs showed increased serum urea and creatinine levels, and the majority had increased total creatine kinase, bilirubin, alkaline phosphatase, and leukocytosis with neutrophilia. One-third were thrombocytopenic. Of dogs with liver-related abnormalities, most had evidence of cholestasis, with or without hepatocellular damage. Based on serologic studies, in the year 2000, the major serovar involved was autumnalis, but bratislava, grippotyphosa, and pomona were also implicated. The microscopic agglutination test often gave a confusing pattern of reactivities to the serovars that were tested. The high reactivity to serovar autumnalis may represent an erroneous or "paradoxical" reaction typical of early leptospiral serology. The year 2000 was the warmest in Ontario in each of the 4 fall months (September-December) of the previous decade, as well as being the third wettest in the fall period in the last decade. The increase in canine leptospirosis, therefore, may, in part, reflect climate change. The number of positive cases declined in 2001 by about one-third of those in 2000, but the number of submissions of sera for diagnosis increased markedly over previous years. Further work is required to isolate and to identify definitively serovars involved in resurgent canine leptospirosis and the common sources for dogs.     

The use of an implantable central venous (Hickman) catheter for long-term venous access in dogs undergoing bone marrow transplantation.

Methods were developed for the insertion and maintenance of long-term central venous catheters in dogs in order to provide reliable venous access during bone marrow transplantation. Single-lumen, 9.6 Fr Hickman catheters with a VitaCuff were used. The catheter was inserted into the jugular vein via a surgical cut-down, and tunnelled subcutaneously to exit over the thoracic spine. Fluoroscopic guidance was necessary to ensure proper positioning of the catheter tip in the right atrium. The catheter was secured at the venous entrance site with a grommet and at the cutaneous exit site with a finger-cuff suture. The exit site was bandaged; dressings were changed daily. Five dogs were studied. Catheter insertion and maintenance techniques were developed using two dogs. For the other three dogs, which developed 7 wk of profound myelosuppression induced by total body irradiation, the catheters were used for blood sampling and infusions of antibiotics, fluids, and blood products. For these three dogs there were 261 total catheter-days. Complete catheter obstruction did not occur. Partial obstruction (inability to withdraw blood) occurred for 13 days with one catheter. The tip of this catheter was in the cranial vena cava. One irradiated dog had a staphylococcal exit site infection for several days after catheter insertion, which resolved with antibiotic therapy. Infections of the subcutaneous tunnel, and catheter associated bacteremia, were not identified. Infectious and hemorrhagic complications of myelosuppression were less severe than in six other dogs where intermittent venipuncture was used for vascular access during radiation induced myelosuppression. In conclusion, long-term central venous catheterization is feasible in dogs during profound myelosuppression and markedly facilitates patient management.     

Rearing performance of farmed fallow deer (Dania dama)

The ability of fallow does to rear fawns to weaning age was examined in a group of 243 adult does of known age (Group 1) and 509 adult does of unknown age (Group 2). All does had between 1 and 8 opportunities to rear fawns. There was an increasing proportion of does that failed to rear a fawn to weaning age as the number of rearing opportunities increased, although most does (93.6%) only failed on one occasion. A small percentage of does in groups 1 and 2 failed repeatedly to rear fawns to weaning. At slaughter, the presumed causes of failure in chronic non-breeders included pyometron, cystic ovaries, cervical cysts, a vulval neoplasm and salpingitis. The overall rearing success of both groups of deer was 82.4% and there was no consistent pattern of rearing failure relating to parity or previous rearing history.