Mantle seismic structure beneath the MELT region of the east pacific rise from P and S wave tomography

Relative travel time delays of teleseismic P and S waves, recorded during the Mantle Electromagnetic and Tomography (MELT) Experiment, have been inverted tomographically for upper-mantle structure beneath the southern East Pacific Rise. A broad zone of low seismic velocities extends beneath the rise to depths of about 200 kilometers and is centered to the west of the spreading center. The magnitudes of the P and S wave anomalies require the presence of retained mantle melt; the melt fraction near the rise exceeds the fraction 300 kilometers off axis by as little as 1%. Seismic anisotropy, induced by mantle flow, is evident in the P wave delays at near-vertical incidence and is consistent with a half-width of mantle upwelling of about 100 km.     

Does the Microbial Flora in the Ejaculate Affect the Freezeability of Stallion Sperm?

In an attempt to evaluate the possible relationship between the microbial flora in the stallion ejaculate and its ability to freeze, three ejaculates from five stallions were frozen using a standard protocol. Before freezing, an aliquot was removed for bacteriological analysis. Bacterial growth was observed in all the ejaculates studied. The isolated microorganisms were: Staphylococcus spp. and Micrococcus spp. (in all the stallions), β-haemolytic Streptococcus (in stallions 3 and 4), Corynebacterium spp. (in stallions 1, 3–5), Rhodococcus spp. (in stallion number 2), Pseudomonas spp. (in stallion number 1) and Klebsiella spp. (in stallions 1, 3 and 5). The presence and richness of Klebsiella and β-haemolytic Streptococcus in the ejaculate were related to two sperm variables post-thaw, namely the proportion of dead spermatozoa (ethidium+ cells; r = 0.55, p < 0.05) and the amplitude of lateral displacement of the sperm head (ALH, μm; r = −0.56, p < 0.05), respectively. The degree of growth of Corynebacterium spp. in the ejaculate was positively correlated with the percentage of spermatozoa showing high caspase activity post-thaw (r = 0.62, p < 0.05). The presence and number of colonies of β-haemolytic Streptococcus were negatively correlated (r = −0.55, p < 0.05) with low sperm caspase activity. It is concluded that the microbial flora of the equine ejaculate may be responsible for some of the sublethal damage experimented by the spermatozoa during cryopreservation.     

Peripartum Haemodynamic Status of Bitches with Normal Birth or Dystocia

There has been limited investigation of parturition in the bitch and there is little information published on clinical and obstetrical examination other than opinion and anecdote. While there are substantial data on haemodynamic and vascular changes during normal parturition in humans, little is known about the physiological events in the dog. This study was aimed at maternal haemodynamic changes occurring during normal parturition and to investigate how these were modified in bitches with dystocia (DYST) treated either medically or via assisted delivery and caesarean operation. Three groups of 10 bitches were investigated; those with normal parturition, those with DYST corrected by manipulative assistance or caesarean operation and those with uterine inertia treated by oxytocin administration. Heart rate, systolic and diastolic blood pressure, electrocardiogram and blood glucose concentration were measured pre-partum, intra-partum, immediately after parturition and 1 h later. Heart rate was high at all times throughout the study and the majority of bitches had normal sinus rhythm. Blood pressure was generally within the normal range, and although systolic and diastolic blood pressure was highest during the intra-partum period and sometimes during the immediate post-partum period, there were no significant differences between groups. All bitches had blood glucose concentrations within the normal range throughout the study although pre-partum concentrations were statistically lower than many of the other time periods. The study provides useful physiological data that will facilitate monitoring and clinical management of bitches throughout normal parturition and DYST.     

Identification of Sperm Subpopulations in Stallion Ejaculates: Changes after Cryopreservation and Comparison with Traditional Statistics

In an attempt to improve the information obtained after computer-assisted sperm analysis (CASA), data from five stallions (three ejaculates from each) were analysed before (fresh, extended semen) and after cryopreservation using traditional statistics as well as a cluster analysis. The data matrix consisted of 13 987 observations of individual spermatozoa for fresh, extended semen, and 8305 for frozen–thawed samples. As expected, freezing and thawing resulted in a marked decrease of CASA-derived variables of sperm kinematics. All sperm velocities were significantly lower in frozen–thawed samples than in samples before cooling. Using sperm velocities, six sperm subpopulations were identified in fresh semen (S1–S6). As such, subpopulations S1 and S2 were characterized by low sperm velocities, subpopulations S3 and S4 corresponded to spermatozoa depicting medium speed values, and finally, subpopulations S5 and S6 were those depicting the highest velocities. After freezing and thawing, four sperm subpopulations were identified, listed as nr FT1 to FT4. While subpopulations FT1–FT3 were characterized by low sperm velocities, and thus corresponded speed-wise to those listed as S1–S4 for fresh, extended semen, the one called number FT4 in frozen semen was characterized by high velocities, of the same range as that of the subpopulations S5 and S6 for fresh spermatozoa. The sperm subpopulation structure varied among stallions, but the cluster analysis hereby assayed was able to provide valuable information about the freezability of the samples that the customary statistics did not reveal.     

Single-Layer Centrifugation Through Colloid Positively Modifies the Sperm Subpopulation Structure of Frozen–Thawed Stallion Spermatozoa

The present study attempted to select the subpopulation of stallion spermatozoa that best survived a conventional freezing and thawing procedure, using centrifugation of post-thawed semen samples through a single layer of a glycidoxypropyltrimethoxysilane-coated silica colloid with a species-specific formulation (Androcoll-E™). After freezing and thawing, four sperm subpopulations were identified, listed as FT1 to FT4. While subpopulations FT1 and FT2 were characterized by low sperm velocity, high velocities characterized the ones called FT3 and FT4. The single-layer centrifugation (SLC)-handled sperm sample was enriched in subpopulation FT3, reaching a proportion of 82.6% of the present spermatozoa, in contrast with the non-filtered control post-thawed semen, where this sperm subpopulation only accounted for 16.3% of the total. It is concluded that in the equine industry, the SLC is a practical, easy-to-perform approach to improve the quality of equine frozen–thawed semen samples.     

Double-outlet right ventricle in a 10-month-old Friesian filly

A 10-month-old Friesian filly had a presentation that was consistent with chronic left- and right-sided congestive heart failure. Clinical pathology findings included abnormal haematological and biochemical variables, abnormal blood gas values and increased serum concentration of cardiac troponin I. Echocardiography revealed cardiac chamber dilation and dextropositioning of the aorta. Radiography revealed a generally enlarged heart and pulmonary interstitial infiltration. These findings were supported at necropsy and the diagnosis of double-outlet right ventricle was confirmed. The pathological changes and physiological responses subsequent to double-outlet right ventricle have not previously been described in detail in horses. Clinical progression closely resembles that seen in humans, in whom antemortem diagnosis relies on echocardiography. In horses, complex cardiac disease presents a diagnostic challenge to the clinician. Appropriate therapy must be based on an accurate diagnosis.     

Alpaca plant poisonings: nitrate–nitrite and possible cyanide

Nitrate–nitrite poisoning killed four adult alpacas and induced the abortion of a full-term fetus after access to oaten hay ( Avena sativa ) containing 3.2% KNO₃ equivalent in dry matter. Necropsy findings were cyanosis, dark-coloured blood, and pulmonary congestion and oedema. Aqueous humour from two adults contained 25 mg NO₃/L and that from the fetus contained 10 mg NO₃/L. Cyanide poisoning possibly killed two adult wether alpacas that ate a garden-cultivated variety of Osteospermum ecklonis (South African daisy, bietou) with a cyanide potential of 6800 mg HCN/kg dry matter.     

Comparison of the brainstem auditory evoked responses during sevoflurane or alfaxalone anaesthesia in adult cats

Objective

To compare the effects of general anaesthesia using sevoflurane or alfaxalone on the brainstem auditory evoked response (BAER) test in adult healthy cats.