Is the Thoroughbred race-horse under chronic stress?

Thoroughbred fillies were divided into three groups according to age: group 1, 7 fillies aged 1 to 2 years (G1) starting the training program; group 2, 9 fillies aged 2 to 3 years (G2) in a full training program; group 3, 8 older fillies 3 to 4 years of age (G3) training and racing. Blood samples were collected weekly from July to December. Cortisol was quantified using a solid phase DPC kit. The intra- and interassay coefficients of variation were 12.5% and 15.65% and sensitivity was 1.9 ± 0.2 nmol/ l. The semester average of cortisol levels varied between groups: G1 = 148.8 ± 6.7, G2 = 125.7 ± 5.8, G3 = 101.1 ± 5.4 nmol/l, with G3 differing statistically from the other groups. The lower cortisol levels observed in the older fillies leads us to propose that the stress stimulus, when maintained over a long period of time, may become chronic and result in a reduction of hypophyseal corticotropin-releasing hormone receptors. The secretion of endogenous opioids may also lead to low serum cortisol levels.

Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol.

Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were removed by successive dilutions in PBS + 15% v:v fetal calf serum (FCS) containing decreasing concentrations of the cryoprotectants. Pregnancy was diagnosed ultrasonographically in 53.3%, 13.3% and 0% of the mares in Groups 1, 2 and 3 respectively. Ultrastructural analysis showed differences between frozen/thawed and fresh embryos. In the former, embryonic cells were deformed and showed dilation of the intercellular and perivitelline spaces, a decrease of desmosome number in the junctional complexes, few microvilli on the apical surface of the trophectoderm and an almost total absence of pinocytotic vesicles. Most of the mitochondria showed regions containing dilation and irregularities on the cristae, which appeared electron-dense. The results obtained with Groups 2 and 3 embryos showed that the cryoprotectants employed were not effective in protecting the embryos against damage during freezing and thawing. Indeed, the ultrastructural changes observed in the Group 3 embryos explained the absence of any established pregnancies in this group of mares.

Ultrastructural study of the lateral lobe of the prostate of Wistar rats submitted to experimental chronic alcohol ingestion

Alcoholism is considered today one of the most serious social and medical problems. Different investigators have demonstrated that chronic exposure to alcohol causes morphological and physiological changes in the testes and in the accessory sex glands, in the prostate in particular. In the present study, experimental rats were divided into groups receiving sugar cane brandy diluted to 30° G.L. (30%, v/v) and Purina ration ad libitum for 60, 120, 180, 240 and 300 days, respectively. At the end of each period the animals were sacrificed and the lateral lobe of the prostate was collected for histological examination. The results showed atrophied epithelium, accumulation of lipidic droplets and rupture of the microvilli that line the cell surface facing the lumen of cells of the secretory epithelium of the lateral lobe of the prostate.

Metabolic Disturbances in Male Broilers of Different Strains. 1. Performance, Mortality, and Right Ventricular Hypertrophy

Two trials were carried out to test the susceptibility for metabolic disturbances of different strains of male broilers. In Trial 1, 1,890 male chickens were allotted in a randomized block design with seven treatments (Arbor Acres, Avian Farms, Cobb-500, Hubbard-Peterson, ISA, Naked Neck, and Ross) and six blocks of 45 chickens. Trial 2 involved 2,184 male chickens of six strains (Arbor Acres, Avian Farms, Cobb 500, Hubbard-Peterson, ISA Naked Neck, and Ross) allotted in seven complete blocks of 52 birds. The same management system was adopted for all birds, reared up to 42 d in an open house during late winter (Trial 1) or late autumn (Trial 2). The most marked differences observed among the strains tested was the lower BW and higher feed conversion of Naked Neck broilers. Total percentage mortalities were high among the most productive broilers, being more than 50% due to sudden death (SDS) and ascites syndrome (AS). No Naked Neck birds died as a consequence of these disturbances and the total mortalities were significantly lower (P ≤ 0.05) than the other strains. The ratio of right ventricle weight to total ventricle weight of the dead birds was over 0.25, except for Naked Neck birds, which presented a nonhypertrophic ratio. The two trials confirmed the relationship between high productivity and high incidence of SDS and AS and indicated that Naked Neck male broilers are resistant to these metabolic disturbances.

Detection of leptospires in bovine semen by polymerase chain reaction

Objective: In view of the considerable importance of venereal transmission of bovine leptospirosis, the objective of the present study was to compare the polymerase chain reaction (PCR), culture/isolation and serology to detect leptospire infection in bovine semen. Design: Blood for serologic examination and semen for bacterial culture and PCR were collected from 20 bulls at artificial insemination centres in Brazil. Each animal was sampled twice for serology. Result: Forty-five percent (9/20) of the serum samples collected showed agglutinin titers to serovar hardjo in the first sample and 25% (5/20) had agglutinin titers to serovar hardjo in the second sample. Eighty percent (16/20) of semen samples were positive by PCR. Leptospires could not be isolated from any of the semen samples examined. Conclusion: Polymerase chain reaction can be a method of great potential for the detection of leptospires at artificial insemination centres.

Influence of canine brain decomposition on laboratory diagnosis of rabies.

Canine brains infected with rabies virus were submitted to decomposition by being left at room temperature of 25 to 29 degrees C for up to 168 h. At 24 h intervals, brain fragments were analyzed by immunofluorescence (IF) and by the mouse intracerebral inoculation (MI) test to confirm the diagnosis of rabies and to measure the putrefaction effect on the accuracy of the diagnosis. Forty eight h after the beginning of the experiment, the MI test showed signs of impairment with four negative results, while after 72 h, 100% of the results were negative to the MI test and only one result was negative to the IF test, indicating that the threshold period for accurate diagnosis is 24 to 48 h before putrefaction. The authors recommend the shipment of suspected cases of rabies to the laboratory for confirmation, but the use of putrid materials for diagnosis is meaningless because of false-negative results.

Metabolic disturbances in male broilers of different strains. 2. Relationship between the thyroid and somatotropic axes with growth rate and mortality

Seven male broiler strains (Arbor Acres, Avian Farms, Cobb-500, Hubbard-Peterson, ISA, Naked Neck, and Ross) were compared for their growth rate, feed efficiency, and mortality due to sudden death and ascites. In addition, weekly plasma levels of thyroid hormones [3,3′,5-triiodothyronine (T3) thyroxine (T4), T3: T4 ratio, growth hormone (GH), and insulin-like growth factor-I (IGF-I)] were determined. The highly productive, commercial strains were very similar in their endocrine profiles but differed markedly from the Naked Neck chickens. Naked Neck chickens were characterized by higher plasma T3 and lower T4 levels at similar ages as well as when compared on the same body weight basis. The present findings support the hypothesis that the slightly hypothyroid state of high productive broilers renders them more sensitive to metabolic disorders. Naked Neck chickens also had higher plasma GH levels than those of their age-matched commercial broilers. The coefficient of variation for GH was highest for Naked Neck chickens, which is indicative for an amplified GH burst amplitude. It may be stated that changes in plasma thyroid hormone concentration in indirect response to selection for low feed conversion and fast growth may be causatively linked to susceptibility for metabolic disturbances such as sudden death syndrome and ascites.

Effect of allopurinol in the course of adriamycin induced nephropathy

The role of superoxide in adriamycin-induced nephropathy (single dose; i.v. 3 mg/kg) has been studied by blocking superoxide synthesis through the administration of allopurinol (500 mg/L in drinking water). In Experiment I (EI), allopurinol administration was started 3 days prior to nephropathy induction and continued until day 14. In Experiment II (EII) allopurinol administration was started 2 weeks after nephropathy induction and was maintained until the end of the experiment (26 weeks). Affected glomeruli frequency and tubulointerstitial lesion index (TILI) were determined at Weeks 2 and 4 (EI) and Week 26 (EII). In EI, and 24 h mean proteinuria in the nephrotic control group (NCG-I) differed from that of the treated nephrotic group (TNG-I) at Week 1 (TNG = 33.3 ± 6.39 mg/24 h; NCG = 59.8 ± 6.3 mg/24 h; p < 0.05) and 2 (NCG-I = 80.0 ± 17.5 mg/24h; TNG-I = 49.1 ± 8.4 mg/24 h; p < 0.05). No glomerular alterations were observed and TILI medians were not different in both nephrotic groups at week 2 (NCG-I = 1+: TNG = 1+) and 4 (NCG = 4+; TNG = 4+). In EII, NCG-II and TNG-II presented different 24 h proteinuria values only at Week 6, (136.91 ± 22.23 mg/24 h ad 72.66 ± 10.72 mg/24 h, respectively; p < 0.05). Between nephrotic groups, there was no statistical difference in the median of affected glomeruli (CNG-II = 56%; TNG-II = 48% and TILI (NCG-II = 8+; TNG-II = 9+). Thus, allopurinol was associated with a transient reduction in proteinuria and it did not alter the progression of the nephropathy.

Repeatability and heritability of response to superovulation in Holstein cows

The objective of this study was to estimate the relative effects of genetic and phenotypic factors on the efficacy and efficiency of superovulation for Holstein-Friesian cows reared in Brazil. A database, established by the Associacao Brasileira de Criadores de Bovinos da Raca Holandesa, consisting of a total of 5387 superovulations of 2941 cows distributed over 473 herds and sired by 690 bulls was used for the analysis. The records were analyzed by MTDFREML (Multiple Trait Derivative-Free Restricted Maximum Likelihood), using a repeatability animal model. The fixed effects included in the model were contemporaneous group (veterinarian, herd, year and season of the superovulation); number of semen doses; cow age; and superovulation order. The estimated repeatability of the number of the transferable embryos was low (0.13), and the estimated heritability was 0.03. These results indicate that environmental factors play a critical role in the response of a cow to a superovulation treatment. There is little evidence that future responses to superovulation by individual females can be predicted by previous treatment(s) or that superovulation response is an heritable trait.

Investigation into the use of the Laryngeal Mask Airway in pentobarbital anesthetized dogs

Objective - To investigate the use of the laryngeal mask airway (LMA) in dogs. Study Design - Prospective experimental study. Animals - Eight healthy adult mixed breed dogs weighing from 15 to 20 kg. Methods - The dogs were anesthetized with intravenous pentobarbital. An LMA was introduced after the induction of anesthesia and 1 L/min O2 plus 1 L/min air was delivered using a circle anesthetic system. Respiratory rate, tidal volume, arterial O2 saturation (pulse oximetry), end tidal CO2, inspired fraction of O2, pulse rate, and mean arterial blood pressure were measured after the insertion of the LMA and 30, 60, 90, and 120 minutes afterwards. Results - There were no changes in respiratory rate, tidal volume, arterial O2 saturation, and pulse rate during anesthesia. End tidal CO2 decreased significantly by the end of anesthesia and ventilation appeared satisfactory. Conclusions - An LMA appeared to be an alternative option to maintain the patency of the airway in dogs. Clinical Relevance - This device may allow safe maintenance of an airway in dogs when intubation is difficult or when it interferes with the procedure (eg, cervical myelography). ©Copyright 1999 by The American College of Veterinary Surgeons.

Increased natural killer activity does not prevent progression of experimental kala-azar

Kala-azar is the visceral form of leishmaniasis and it is caused by intracellular parasites from the complex Leishmania donovani. Golden hamster (Mesocricetus auratus) infected with Leishmania donovani develop a disease very similar to human Kala-azar. There is conspicuous hipergammaglobulinaemia and their T cells do not respond to stimulation with parasite antigens. We used this experimental model to evaluate the natural killer (NK) activity during the initial phase of the disease. Outbred hamsters infected by intravenous route with 5.106 amastigotes of L. donovani 1S showed a concurrent increase in the spleen weight and in the spleen cell number. Using the single cell assay we detected a significant increase in the percentage of NK effector cells on the 4th day of infection. Imprints from spleen and liver showed at days 14 and 28 a significant increase in the parasite burden. These results show that the increased NK activity in the beginning of the infection was not able to restrain the progression of the disease in this experimental model.

Ticks (Acari: Ixodidae) associated with wild animals in the Pantanal region of Brazil

This paper describes the identification of ticks from wild animals of the Pantanal region in Brazil as part of a comprehensive study about established and emerging tick-host relationships and related pathological aspects. Eighty-one animals were captured (representing 13 species six orders), and ticks were found on 63 (78%). Tick species identified included Boophilus microplus (Canestrini), Amblyomma cajennense (F.), Amblyomma parvum Aragão, Amblyomma pseudoconcolor Aragão, Amblyomma scalpturatum Neumann, Amblyomma nodosum Neumann, Amblyomma ovale Koch, and Amblyomma tigrinum Koch. Dragging from grasslands yielded negative results compared with the high concentration of ticks that were collected from leaves in the forests.

The effect of changing the mode of ventilation on the arterial-to-end-tidal CO2 difference and physiological dead space in laterally and dorsally recumbent horses during halothane anesthesia

Objective - To evaluate the effect of changing the mode of ventilation from spontaneous to controlled on the arterial-to-end-tidal CO2 difference [P(a-ET)CO2] and physiological dead space (VD(phys)/VT) in laterally and dorsally recumbent halothane-anesthetized horses. Study Design - Prospective, experimental, nonrandomized trial. Animals - Seven mixed breed adult horses (1 male and 6 female) weighing 320 ± 11 kg. Methods - Horses were anesthetized in 2 positions - right lateral and dorsal recumbency - with a minimum interval of 1 month. Anesthesia was maintained with halothane in oxygen for 180 minutes. Spontaneous ventilation (SV) was used for 90 minutes followed by 90 minutes of controlled ventilation (CV). The same ventilator settings were used for both laterally and dorsally recumbent horses. Arterial blood gas analysis was performed every 30 minutes during anesthesia. End-tidal CO2 (PETCO2) was measured continuously. P(a-ET)CO2 and VD(phys)/VT were calculated. Statistical analysis included analysis of variance for repeated measures over time, followed by Student-Newman-Keuls test. Comparison between groups was performed using a paired t test; P < .05 was considered significant. Results - P(a-ET)CO2 and VD(phys)/VT increased during SV, whereas CV reduced these variables. The variables did not change significantly throughout mechanical ventilation in either group. Dorsally recumbent horses showed greater P(a-ET)CO2 and VD(phys)/VT values throughout. PaCO2 was greater during CV in dorsally positioned horses. Conclusions and Clinical Relevance - Changing the mode of ventilation from spontaneous to controlled was effective in reducing P(a-ET)CO2 and physiological dead space in both laterally and dorsally recumbent halothane-anesthetized horses. Dorsal recumbency resulted in greater impairment of effective ventilation. Capnometry has a limited value for accurate estimation of PaCO, in anesthetized horses, although it may be used to evaluate pulmonary function when paired with arterial blood gas analysis. © Copyright 2000 by The American College of Veterinary Surgeons.