W. Kähn

Blood gas and acid-base analysis of arterial blood in 57 newborn calves

The pH, partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), concentration of bicarbonate (HCO−3), base excess and oxygen saturation (SO2) were measured in venous and arterial blood from 57 newborn calves from 55 dams. Blood samples were collected immediately after birth and 30 minutes, four, 12 and 24 hours later from a jugular vein and a caudal auricular artery. The mean (sd) pO2 and SO2 of arterial blood increased from 45·31 (16·02) mmHg and 64·16 (20·82) per cent at birth to a maximum of 71·89 (8·32) mmHg and 92·81 (2·32) per cent 12 hours after birth, respectively. During the same period, the arterial pCO2 decreased from 57·31 (4·98) mmHg to 43·74 (4·75) mmHg. The correlation coefficients for arterial and venous blood were r=0·86 for pH, r=0·85 for base excess and r=0·76 for HCO−3. The calves with a venous blood pH of less than 7·2 immediately after birth had significantly lower base excess and HCO−3 concentrations for 30 minutes after birth than the calves with a venous blood pH of 7·2 or higher. In contrast, the arterial pO2 was higher in the calves with a blood pH of less than 7·2 than in those with a higher pH for 30 minutes after birth.

Influence of seminal plasma on fertility of fresh and frozen-thawed stallion epididymal spermatozoa

The use of epididymal stallion spermatozoa for routine artificial insemination can secure easy future use of valuable genetics after unforeseen death or injury of a valuable stallion. The aims of this study were to (1) directly compare pregnancy rates for fresh and frozen-thawed stallion epididymal and ejaculated spermatozoa after conventional artificial insemination and (2) to investigate the effect of seminal plasma on the fertility of epididymal spermatozoa after insemination. Twenty-one mares were randomly assigned to three stallions. Mares were inseminated at five consecutive oestrous periods using fresh ejaculated spermatozoa (Fr-E, n=18), fresh epididymal spermatozoa that had been exposed to seminal plasma (Fr-SP+, n=12) or fresh epididymal spermatozoa that had never been exposed to seminal plasma (Fr-SP-, n=9), frozen-thawed ejaculated spermatozoa (Cr-E, n=18), frozen-thawed epididymal spermatozoa that had been exposed to seminal plasma prior to freezing (Cr-SP+, n=18) and frozen-thawed epididymal spermatozoa that had never been exposed to seminal plasma (Cr-SP-, n=15). Pregnancy examinations were performed 14 days after each ovulation. Pregnancy rates were 55.6% (Fr-E, 10/18), 75% (Fr-SP+, 9/12), 22.2% (Fr-SP-, 2/9), 38.9% (Cr-E, 7/18), 27.8% (Cr-SP+, 5/18) and 6.7% (Cr-SP-, 1/15). Overall pregnancy rates for fresh and frozen-thawed epididymal spermatozoa that had been exposed to seminal plasma were significantly better than for epididymal spermatozoa that had never been exposed to seminal plasma (P<0.05). We conclude that the exposure of stallion epididymal spermatozoa to seminal plasma improves pregnancy rates.

Fixed-time AI pregnancy rate following insemination with frozen-thawed or fresh-extended semen in progesterone supplemented CO-Synch protocol in beef cows

The objective of this study was to compare fixed-time AI pregnancy rate in Angus crossbred beef cows inseminated with frozen-thawed or fresh-extended semen. Two ejaculates from each of two Angus bulls were collected by artificial vagina and pooled for each bull. The pooled semen from each bull was divided into two aliquots; Aliquot 1 was extended using Caprogen (LIC, Hamilton, New Zealand) to a concentration of 3 x 10(6)sperm/straw and Aliquot 2 was extended using egg-yolk-glycerol extender to a concentration of 20 x 10(6)sperm/straw. Semen extended with Caprogen was maintained at ambient temperature and semen extended with egg-yolk-glycerol extender was frozen and maintained at -196 degrees C until insemination. In each of two breeding seasons (Fall 2007 and Spring 2008), Angus-crossbeef cows (N=1455) at 12 locations were randomly assigned within location to semen type [Fresh (N=736) vs. Frozen (N=719)] and sire [1 (N=731) vs. 2 (N=724)]. All cows were synchronized with 100 microg of GnRH im and a progesterone Controlled Internal Drug Release insert (CIDR) on Day 0, and on Day 7, 25mg of PGF2(alpha) im and CIDR removal. All cows received 100 microg of GnRH im and were inseminated at a fixed-time on Day 10, 66 h after CIDR removal. Timed-AI pregnancy rates were influenced by season (P<0.05), cows detected in estrus prior to and at AI (P<0.001), and dam age (P<0.01). Pregnancy rates were not affected by semen type (Fresh=51.5% vs. Frozen=50.4%; P=0.66) and there were no significant interactions of semen type by estrus expression, semen type by sire, or semen type by season (P>0.1). In conclusion, commercial beef cows inseminated with fresh-extended semen (3 x 10(6)sperm/straw) yielded comparable pregnancy rates to conventional frozen-thawed semen in a progesterone supplemented, CO-Synch fixed-time AI synchronization protocol and may provide an alternate to frozen semen for more efficient utilization of superior genetics.

Effect of intranasal oxygen administration on blood gas variables and outcome in neonatal calves with respiratory distress syndrome : 20 cases (2004-2006)

OBJECTIVE To determine the effect of intranasal oxygen administration on blood gas variables and outcome in neonatal calves with respiratory distress syndrome (RDS). DESIGN Retrospective case series. ANIMALS 20 neonatal calves with RDS. PROCEDURES Arterial partial pressure of oxygen (PaO(2)), arterial partial pressure of carbon dioxide, and arterial oxygen saturation (SaO(2)) before and after intranasal administration of oxygen were analyzed. RESULTS There were significant increases in PaO(2) and SaO(2) in the first 24 hours after oxygen administration was begun, with mean +/- SD PaO(2) increasing from 38.4+/-8.8 mm Hg to 58.7+/-17.8 mm Hg during the first 3 hours of treatment. Calves with PaO(2)>55 mm Hg within the first 12 hours after oxygen administration was begun had a significantly higher survival rate (9/10) than did calves that did not reach this threshold (4/10). CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that intranasal oxygen administration was a simple method of improving blood gas variables in neonatal calves with RDS and that PaO(2) could be used to predict outcome.

Ex vivo influence of carbetocin on equine myometrial muscles and comparison with oxytocin

To determine the intercyclic effect of oxytocin and carbetocin on equine myometrial tissue, the effect of the drugs was evaluated through pharmacokinetic and pharmacodynamic studies. The complete pharmacokinetic profile for oxytocin was unknown and had to be established. To do so, 25 IU of oxytocin were administered intravenously to six cycling mares and blood samples were collected before and 2, 4, 8, and 15 min after administration. The half-life of oxytocin was determined to be 5.89 min, the clearance rate 11.67 L/min, mean residence time (MRT) 7.78 min. The effective plasma concentration was estimated to be 0.25 ng/mL. This was similar to the concentration achieved for the organ bath study where the concentration that produced 50% of the maximum effect (EC(50)) was calculated at 0.45 ng/mL. To determine the intercyclic effect of oxytocin and carbetocin uterine myometrial samples were collected from slaughtered mares in estrus, diestrus, and anestrus. The samples were mounted in organ baths and exposed to four ascending, cumulative doses of oxytocin and carbetocin. Area under the curve and amplitude, maximum response (E(max)), and concentration that produced 50% of the maximum effect were studied for each agonist and statistically evaluated. The effect of oxytocin on equine myometrial tissue was higher during diestrus, and surprisingly anestrus, than during estrus, whereas the effect of carbetocin was the same independent of the stage of estrous cycle. A significant difference was found for estrous and anestrous samples when oxytocin was used but not when carbetocin was used.

Thrombosis of the ovarian and vaginal veins after caesarean section in a cow

IN human medicine, the frequency of ovarian vein thrombophlebitis after caesarean section or vaginal birth is 0·02 to 0·18 per cent of all pregnancies (Johnson and Esclapes 1998). To the authors’ knowledge, thrombosis of the ovarian and/or uterine veins has not been reported in the veterinary literature. In cattle, the clinically most relevant thromboses are those affecting the caudal vena cava (Mills and Pace 1990, Braun and others 1992, 2002, 2003, Bueno and others 2000) and jugular vein, particularly after the administration of drugs or the use of an indwelling catheter (Pusterla and Braun 1995, Rouleau and others 2003). This short communication describes the clinical, bacteriological and pathological findings in a seven-and-a-half-yearold Holstein-Friesian cow with thrombosis of the uterine branches of the vaginal vein and the right ovarian vein. The cow was referred to the Clinic of Reproductive Medicine of the University of Zurich because of dystocia. A vaginal examination revealed that the calf had a breech presentation and left dorsoilial position. Because the breech presentation could not be corrected, a caesarean section was performed. Paravertebral anaesthesia was administered via the left paralumbar flank. After clipping the hair and preparing the skin for surgery, the abdominal wall was incised. The left uterine horn was exteriorised and incised, and two live male calves were delivered. The placentas could be only partially removed intraoperatively. Two uterine antibiotic pessaries containing 1000 mg tetracycline and 500 mg clioquinol (Injecur; Veterinaria) were placed in the uterus. The uterus and abdomen were then closed routinely, and the cow and calves were discharged from the clinic. During the following 40 days, the cow had an intermittent fever and had a reduced food intake and milk yield. The clinical signs resolved with antibiotic therapy but recurred when the treatment was discontinued. The cow was therefore transferred to the authors’ clinic. The cow’s general condition was moderately depressed, and its rectal temperature was 40·6°C. The heart rate was 92 bpm and the respiratory rate was 44 breaths/minute; both were higher than normal. The ruminal and intestinal motility were reduced. The cow was moderately lame on the right hindlimb due to a sole ulcer of the lateral claw and footrot in the interdigital region; it remained mildly lame after treatment of these conditions. Transrectal palpation revealed that the uterus was flaccid and thicker than normal, and could not be retracted. The left uterine horn was not freely movable and was smaller than the right horn. Transrectal ultrasonography revealed the presence of hypoechogenic fluid in both uterine horns. The ovaries contained follicles up to 5 mm in diameter but no other structures were visible. An echogenic thrombus was seen in the right ovarian vein, starting at the ovary and extending for approximately 20 cm. The thrombus was 3·5 cm in diameter, had an ‘onion ring’ appearance and occluded the vein almost completely (Fig 1). Ultrasound-guided transvaginal centesis of the thrombus yielded polyhedral squamous cells and a small number of leucocytes, which corresponded to a hypocellular aggregation of thrombocytes. Bacteriological examination of the aspirate revealed a large number of Arcanobacterium pyogenes. The uterus and vagina contained a yellowish, serous secretion, which smelled like urine and contained a few strands of pus. The results of haematological and biochemical analyses revealed a shorter than normal glutaraldehyde clotting test time, leucopenia (2·0 x 103 leucocytes/μl, reference range 4·0 x 103 to 8·8 x 103 leucocytes/μl), anaemia (haematocrit 20 per cent, reference range 25 to 33 per cent; erythrocyte count 3·87 x 106/μl, reference range 4·9 x 106 to 6·9 x 106/μl) and bilirubinaemia (10·2 μmol/l, reference range 1·5 to 2·9 μmol/l). The owner requested inexpensive treatment for the cow. The uterus was lavaged with 10 litres of warm saline solution, and the cow received 20 g metamizole (Vetalgin; Veterinaria) intravenously and 10 litres of 5 per cent glucose solution intravenously via an indwelling venous catheter. The cow’s general condition improved over the following seven days, and its rectal temperature ranged from 38·5 to 39·1°C. The cow was then discharged. In a follow-up examination, nine weeks after discharge, the owner reported that there had been no recurrence of the clinical signs and that the cow was producing 40 to 45 litres of milk per day. Transrectal ultrasonography showed that the right ovarian artery still contained a thrombus, which was 15 cm in length, 3·5 cm in diameter and completely occluded the lumen. The right ovary had a 35 mm corpus luteum as well FIG 1: (a) Ultrasonogram and (b) postmortem specimen of a thrombus (T) and abscess (A) within the right ovarian vein of a seven-and-a-half-year-old Holstein-Friesian cow (a)

Influence of long-term treatment with equine somato-tropin (EquiGen®) on gonadal function in stallions with poor semen quality

The aim of the present study was to investigate the spermatogenic and Leydig cell activity in stallions with impaired semen quality after treatment with equine somatotropin. Experiments were performed using 18 adult clinically healthy stallions with poor semen quality which did not pass breeding soundness evaluation. The animals were randomly divided into a treatment (n = 9) and a control (n = 9) group. Over a period of 90 days, nine stallions received a daily intramuscular injection of 10 mg recombinant equine somatotropin (EquiGen, BresaGen Limited, Adelaide, Australia) and 9 control animals were injected with the same amount of physiological saline solution. During and until 2 months after treatment, semen characteristics and daily sperm output as well as plasma testosterone concentrations were determined monthly in all stallions. In addition, testosterone concentration measurement after stimulation with hCG was performed in all animals immediately before and at the end of the treatment period as well as 2 months later. Our results demonstrate that equine somatotropin (EquiGen) given daily in a dose of 10 mg per animal during 90 days had no significant effect neither on plasma testosterone concentrations and hCG-induced testosterone release nor on semen quality parameters in adult stallions with poor semen characteristics.