Epidemiological Description of Cystic Ovarian Disease in Argentine Dairy Herds: Risk Factors and Effects on the Reproductive Performance of Lactating Cows

To describe the epidemiology of cystic ovarian disease (COD), to find possible risk factors associated with the incidence of cysts and to analyse the impact of COD on the reproductive performance of dairy cows, databases from 22 dairy herds from the main dairy region in Argentina were retrospectively evaluated throughout a 3‐year period (2009–2011). A total of 248 COD cases over 9156 parturitions were recorded, resulting in a cumulative incidence rate of 2.7%. Cystic ovarian disease incidence density was lower during the first 100 days post‐partum (DPP) than during later stages of lactation. Seasonality had a significant influence on the disease presentation with higher incidence rates during winter and spring. Cows with a previous diagnosis of clinical mastitis showed 2.72 times more chances of developing ovarian cysts. Cystic cows had longer calving to first service and calving to conception intervals and lower conception rate than controls.     

Spontaneous contractions of intestinal smooth muscle re-aggregates from the new-born rat triggered by thromboxane A2

Isolated smooth muscle cells from the small intestine of new-born rats were prepared by enzymatic digestion. These cells re-aggregate after 1 day in culture to clusters. The re-aggregates show spontaneous rhythmical contractions at 37 degrees C with a frequency (13.1 +/- 0.8 min-1, n = 49), which is similar to that of the intact smooth muscle layer. The cholinergic agonist carbachol (5 x 10(-5) mol l-1) caused an increase in the frequency of the spontaneous contractions often ending in a permanent contraction. A similar effect was achieved with the thromboxane A2 (TXA2) agonist, U-46619 (10(-5) mol l-1). In contrast, both the TXA2 receptor blocker, Bay u3405 (5 x 10(-4) mol l-1), as well as the Ca2+ channel blocker, verapamil (5 x 10(-5) mol l-1), suppressed the spontaneous contractions. The observed contractility was insensitive against the neuronal blocker tetrodotoxin (10(-6) mol l-1). These analyses of video images were supported by the measurement of relative changes in the intracellular Ca2+ concentration with the Ca(2+)-sensitive dye, fura-2. Spontaneous contractions were paralleled by spikes in the intracellular Ca2+ concentration, which were abolished by Bay u3405, but stimulated by U-46619 or carbachol. In summary, these results obtained at re-aggregates of intestinal smooth muscle cells support the hypothesis of a role of TXA2 in the generation of spontaneous intestinal smooth muscle contractions in vitro.     

Acute and Chronic Effects of a Contraceptive Compound RTI‐4587‐073(l) on Testicular Histology and Endocrine Function in Miniature Horse Stallions

The objective of this study was to evaluate acute endocrine effects as well as histological changes in testicular parenchyma induced by the contraceptive compound RTI‐4587‐073(l). Six miniature stallions were used in this experiment. The treatment group (n = 3) received one oral dose of 12.5 mg/kg of RTI‐4587‐073(l), and the control group (n = 3) received placebo only. The stallions' baseline parameters (semen, testicular dimensions, endocrine values) were collected and recorded for 5 weeks before treatment and for 6 weeks after treatment. Multiple blood samples were collected for endocrine analysis. Testicular biopsies were obtained before treatment, 1 day after treatment and every other week after treatment. Ultrasound exams were performed to monitor the dimensions of the stallions' testes. All stallions were castrated 6 weeks after treatment. Sperm numbers, motility and percentage of morphologically normal sperm decreased (p < 0.05), while the number of immature germ cells increased in ejaculates from treated animals (p < 0.05). Serum concentrations of inhibin and follicle‐stimulating hormone did not change. Testosterone concentrations initially transiently decreased (p < 0.05) after administration of RTI‐4587‐073(l), and increased several days later (p < 0.05). Testicular content of testosterone and estradiol 17‐β was lower in treated stallions than in control stallions on Day 1 after treatment (p < 0.05). Severe disorganization of the seminiferous tubules, significant loss of immature germ cells and complete depletion of elongated spermatids were observed in testicular biopsies obtained from treated stallions 1 day, 2 and 4 weeks after treatment. These changes were still present in the testicular samples taken from treated stallions after castration. The results of this study confirmed that RTI‐4587‐073(l) has antispermatogenic effects in stallions. Furthermore, we concluded that this compound causes acute sloughing of immature germ cells from the seminiferous tubules. RTI‐4587‐073(l) has significant but transient effects on Leydig cell function in stallions.     

Endoscopy of the upper respiratory tract during treadmill exercise: a clinical study of 100 horses

SUMMARY: Endoscopy of the upper respiratory tract was performed in 100 horses during high speed treadmill exercise. Reasons for endoscopy were a history of an abnormal noise during exercise in 75 horses, poor performance in 17 horses and to evaluate the results of upper respiratory tract surgery in 8 horses. Of the 75 horses with a history of an abnormal noise during exercise the cause was determined in 67 (89%). Endoscopic abnormalities were detected at rest in 40 of these 75 horses (53%). In these 40 horses, a similar diagnosis as to the cause of the abnormal noise was made at rest and during exercise on the treadmill in 19 cases, while in the remaining 21 the endoscopic findings during exercise varied from that seen at rest. This included 3 horses in which a diagnosis was made at rest but no abnormalities were detected during exercise. Some of the findings during treadmill endoscopy included laryngeal dysfunction, grades 3, 4 and 5 (22 cases), dorsal displacement of the soft palate (20), epiglottic entrapment (8), epiglottic flutter (4), aryepiglottic fold flutter (4), pharyngeal collapse (3), arytenoiditis (3), vocal cord flutter (3), false nostril noise (2), pharyngeal lymphoid hyperplasia (2), soft palate haemorrhage (1) and positional arytenoid collapse (1). More than one abnormality was observed during exercise in 7 horses. A complete and correct diagnosis based on the resting endoscopy findings alone was made in 19 (25%) of these 75 cases. In the 17 horses examined because of poor performance, no abnormalities were detected during treadmill endoscopy that were not evident at rest. None of these 17 horses presented with a history of an abnormal respiratory noise, although one, diagnosed as having grade 4 laryngeal function at rest and exercise, did make a characteristic inspiratory noise during treadmill exercise. Eight horses were evaluated after surgery for correction of laryngeal hemiplegia, as the post-operative performance or the amount of respiratory noise present was considered unsatisfactory. Of these, 3 were found to have a satisfactory airway during exercise and other reasons for poor performance were detected; 3 had insufficient abduction; and 2 had intermittent dorsal displacement of the soft palate. Endoscopy of the upper respiratory tract was found to be a useful technique for evaluating the cause of abnormal respiratory noise in most cases. We concluded that treadmill endoscopy in horses presented for poor performance, without a history of an abnormal respiratory noise, was of little value. The technique, in conjunction with arterial blood gas measurements, was useful in determining the efficacy of surgical treatment of laryngeal hemiplegia.     

Boar Sperm Encapsulation Reduces In Vitro Polyspermy

A boar sperm encapsulation technology in barium alginate has been developed to enhance reproductive performances and spermatozoa preservation time; aim of this work was to evaluate the effect of in vitro sperm encapsulation on polyspermy as a function of storage time at 18°C. A total number of 40 in vitro fertilization (IVF) tests were performed using encapsulated or diluted spermatozoa (20 IVF each treatment). Overall, 1288 in vitro matured oocytes were fertilized with spermatozoa stored at 24, 48 or 72 h at 18°C for both treatments polyspermy and normospermy, and the non‐penetration rates were assessed by optical microscopy. Results indicate a significant reduction in risk of polyspermic oocytes when spermatozoa are preserved in barium alginate membranes (incidence risk ratio: 0.766 with respect to diluted); such enhancement could be explained by lesser damage of sperm membranes achieved by encapsulation technology.     

The relationship of training milestones with racing success in a population of Standardbred horses in New Zealand

AIM: To gather information on the repeatability of a faecal nematode egg count (FEC) reduction (FECR) test (FECRT), evaluating both different methods of calculating efficacy and variations within a method, in order to supply veterinarians and other advisors with sufficient information to apply some level of confidence around a diagnosis of anthelmintic resistance based on FECRT results.

METHODS: Two commercial sheep farms were selected on the basis of having previously recorded FECR <95% after treatment with ivermectin (Farm 1) or albendazole (Farm 2). On each farm at least 250 lambs, managed as a single mob, were individually ear-tagged and sampled for FEC. The resulting counts were used, 3—4 days later, to sort the lambs into 24 groups of 10. First, the animals were split into three groups of 80, having high, medium or low FEC. Second, within each of these groups the 80 animals were further divided into four replicate mobs of 20 (each with the same mean count). Third, each of these replicates was further split into two groups of 10: those that would be drenched and those that would remain as untreated controls. All animals were again faecal-sampled and those in the drenched groups were dosed, using a syringe, to their individual liveweight, with ivermectin (Farm 1) or albendazole (Farm 2). Ten days after treatment all animals were individually faecal- sampled again. FEC and larval cultures were undertaken for all 24 groups from both pre- and post-treatment samples. Ef- ficacy (FECR) of the undifferentiated FECRT was calculated using three different equations, and efficacy by genus was also calculated.

RESULTS: Calculated efficacies differed between equations, and the equation which did not utilise an untreated control yielded significantly lower efficacy estimates on both farms. Faecal cultures varied considerably in the proportions of parasite genera recovered. In general, this did not differ between FEC groups, except on Farm 1 where Haemonchus spp were more common and Cooperia spp less common in high-FEC samples. Estimated efficacies against individual genera varied considerably or very little, depending on the level of resistance. On both farms, differing proportions of tests against some genera passed or failed FECRTs based on a threshold pass mark of ≥95% FECR.

CONCLUSION: There was considerable variability in the outcomes of FECRTs and in larval culture results. Caution is warranted in interpreting the results of FECRTs when efficacy values fall into the 90—95% range. Further, the possibility of a test returning a false-negative result is raised, indicating that even an efficacy estimated ≥95% may not guarantee the absence of resistant parasites.