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Biomedical subjects

H Dobson

Publications and source records attributed to H Dobson.

At least 91 records · Page 5Linked to original sources
PubMed1994

Postoperative evaluation of the surgical treatment of accessory teat and gland cistern complexes in dairy cows.

The purpose of this study was the long-term evaluation of a method of surgically repairing the abnormal condition of accessory teat and gland cistern complexes in dairy cattle. A prospective evaluation of three cows that had undergone the procedure was done. These cows were evaluated from four months to one year, postoperatively. A thorough history, physical examination, contrast radiography, and ultrasonic examination were done on each cow. A retrospective evaluation of an additional 13 cows that had also undergone the procedure was obtained four months to three years following the surgery, via owner communication. The prospective portion of this study demonstrated patency of the communication between main and accessory teat cisterns. Postoperative complications included initial slow milking and mild swelling of the involved teat. These problems resolved in all cows one to two months postoperatively. None of the 16 cows that had undergone the surgery either developed or was treated for mastitis. Likewise, none of these cows was sold or slaughtered as a result of postoperative teat problems or unsatisfactory milk production. Our study demonstrated that this particular method of surgical correction of accessory teat and gland cistern complexes is effective, is esthetically acceptable, produces minimal associated complications, and preserves the milk production capacity of the gland.

Animals↗
PubMed1993

Effects of gonadotrophin releasing hormone administered 11 days after insemination on the pregnancy rates of cattle to the first and later services.

In a trial using 2530 recorded services of 1619 animals on 19 commercial dairy farms, alternate cows were injected intramuscularly with 10 micrograms buserelin, an analogue of gonadotrophin releasing hormone (GnRH), (Receptal; Hoechst Animal Health) 11 days after insemination. Pregnancy was diagnosed manually six to 12 weeks after the last service in all but three herds, for which calving data were collected. The pregnancy rates were calculated for control and treated cows, paired for calving to first service interval, parity and week of service. For 520 pairs of control and treated cows the pregnancy rates to first service were 50.6 per cent and 60 per cent, respectively (P < 0.01). For the second and subsequent services each cow was grouped according to its treatment or control status in the immediately preceding dioestrus period, in addition to its status on day 11 after service. As a result there were three treated groups: treated, treated; treated, control, and control, treated for comparison with the control, control group. For 136 pairs of control, control and control, treated cows the pregnancy rates to second service were 41.2 per cent and 54.4 per cent, respectively (P < 0.05), and for 67 similar pairs of cows the pregnancy rates to the third or later service were 23.9 per cent and 52.2 per cent, respectively (P < 0.001). For 40 pairs of control, control and treated, treated cows the pregnancy rates to the third or later service were 15.0 per cent and 45.0 per cent, respectively (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Assessment of fetal number, and fetal and placental viability throughout pregnancy in cattle.

Production of identical twin calves by embryo demisection requires a reliable system for continual monitoring of pregnancy. Both halves of bisected embryos were replaced nonsurgically into one uterine horn on Day 7 in 80 recipients. Monthly blood sampling began on Day 22 of pregnancy and transrectal echography took place between 50 and 80 days. Fifty-four recipients had elevated plasma progesterone concentrations on Day 22 (67% pregnancy rate). Of 21 pregnancies diagnosed as twins by echography, 15 live sets were born, 3 singles accompanied by a stillbirth, and 3 complete abortions. Twenty-five singleton pregnancies resulted in 23 live calves, 1 still-birth and 1 abortion. It was not possible to monitor echographically the remaining 8 pregnancies. At all stages of pregnancy studied, mean concentrations of bovine pregnancy-specific protein B (bPSPB) and estrone sulphate were higher (P<0.01) in twin (n = 17) than in single (n = 26) pregnancies, but the high individual variation obviated any predictive value for fetal number. Although bPSPB and estrone sulphate concentrations were positively correlated at most stages of normal pregnancies after Day 100, divergence was observed in the unsuccessful pregnancies between the concentrations of all 3 hormones, suggesting synthesis/release is under independent control. Measurement of bPSPB may be useful for prediction of fetal well-being, whereas estrone sulphate may reflect placental viability.

Journal Article↗
PubMed1992

Observations on the genital tract of cull ewes.

Genital tracts were collected from non-pregnant cull ewes in early April and examined for macroscopic abnormalities. An assessment was made of the possible effect of any abnormality on the ability of the animal to become pregnant. It was found that 23.2 per cent of the tracts had abnormalities and it was considered that 16.8 per cent had abnormalities likely to interfere with the establishment of pregnancy.

Animals↗
PubMed1992

Neutron therapy in Saudi Arabia: an overview and results of dose searching study in head and neck cancer.

The King Faisal Specialist Hospital and Research Centre is the only center in the Middle East that incorporates a neutron therapy facility. The neutron beam is produced by a cyclotron, which produces a beam by either a (d(15)+Be) or (p(26)+Be) reaction. The beam from the proton reaction is selected for therapy because of its superior physical characteristics. These were verified by an intercomparison conducted by the European Organization for Research on Treatment of Cancer (EORTC) Heavy Particle Therapy Group. Full beam data are presented. The first study in the neutron therapy Program is on the treatment of squamous cancers of the head and neck. This consists of two parts. Part I is a dose searching phase and Part II is a comparison of our current photon treatment versus neutrons using the neutron dose selected by Part I of the study. Results of the dose searching phase (Part I) are presented.

Carcinoma, Squamous Cell↗
PubMed1992

Opioid modulation of the hypothalamo-pituitary-adrenal axis in dairy cows.

Plasma cortisol responses to an intravenous bolus treatment with 250 mg naloxone, 300 mg morphine or a combination, were studied in Holstein-Friesian cows; 4 in early lactation (29-43 d postpartum) and 7 in mid-lactation (90-155 d post-partum). Blood samples were collected every 15 min from 60 min before to 90 min after treatment. Naloxone induced an immediate increase in cortisol concentration, reaching a peak within 30 min. The cortisol response (area under the curve) was positively correlated with pre-naloxone cortisol concentrations (r = 0.7, p < 0.05). The mean increase in cortisol concentration after naloxone appeared to be lower in early lactation (1.8 ng/ml) than in mid-lactation (8.3 ng/ml). In contrast, morphine consistently suppressed mean tonic plasma cortisol concentration by 2.7 ng/ml below baseline for at least 90 min. When given with morphine, naloxone counteracted the suppressive effects; the cortisol response was similar to that after naloxone alone. A cow in mid-lactation, suffering from chronic lameness (joint infection), gave opposite results, i.e., treatment with morphine alone increased cortisol concentration, whereas morphine with naloxone did not result in the expected large increase in plasma cortisol concentration. In conclusion, the hypothalamo-pituitary-adrenal axis of dairy cows appears to be under suppressive opioidergic control. However, the opioidergic system involved in hypothalamo-pituitary-adrenal functions of an animal under chronic stress behaved in an opposite manner.

Analysis of Variance↗
PubMed1991

Increased hyaluronate synthesis and changes in glycosaminoglycan ratios and molecular weight of proteoglycans synthesised by cultured cervical tissue from ewes at various stages of pregnancy.

Culture of cervical tissue with radiolabelled precursors showed that, in pregnant ewes, net hyaluronate synthesis increased between days 120-140 but that the marked polydispersity of hyaluronate remained unchanged. In the less sulphated of two proteoglycan populations, the proportion of heparan sulphate increased and that of dermatan sulphate decreased, while the less polydisperse more highly sulphated species showed a significant increase in molecular weight with pregnancy.

Animals↗
PubMed1991

Effect of prostaglandin treatment on the fertility of problem cows.

Four autumn-calving dairy herds were selected to investigate the effect of an injection of prostaglandin in the period 14 to 28 days (mean 22 days) after calving on subsequent fertility. The cows were selected on the basis of having a condition likely to affect their fertility, including assisted calving, endometritis, retained fetal membranes, milk fever, cows with five or more lactations, cows having twins, or a combination of any of these conditions. They were assigned to treatment or control groups and paired as closely as possible on the basis of their condition and date of calving. Milk progesterone concentrations were measured on the day of treatment and then three and 10 days later. The trial ran for four months and involved 90 treated and 90 control cows. The combined data from all the animals in the trial failed to show any difference between the calving to conception interval, the first service conception rate or the numbers of services per conception of the treated and control groups. A Student's paired t test for groups of cows with a particular condition, both within individual herds and in all the herds, failed to show any significant effect of treatment (P greater than 0.05). Milk progesterone data showed that the presence of a corpus luteum did not influence the outcome of prostaglandin treatment. There was no evidence for excessive failure of luteolysis. It was concluded that there was no benefit in a routine injection of prostaglandin to dairy cows in the period 14 to 28 days after calving when re-breeding commenced more than 70 days after calving.

Animals↗
PubMed1991

Lack of LH response to oestradiol treatment in cows with cystic ovarian disease and effect of progesterone treatment or manual rupture.

The luteinising hormone (LH) surge in response to 1 mg oestradiol benzoate intramuscular injection was studied on 67 occasions in 45 cows with cystic ovarian disease 20 to 150 days post partum. Cows diagnosed as having luteal cysts were given 500 micrograms cloprostenol intramuscularly 24 hours before oestradiol, to induce luteolysis. Oestradiol benzoate was also given to eight post partum acyclic and eight cyclic cows and in all these cases a control LH response was characterised for comparison. Eight of 17 cows with luteal cysts (47 per cent), and 10 of 21 cows with follicular cysts (48 per cent), released LH in response to oestradiol. Some cows with cysts were given one of two treatments. Seven cows with follicular cysts were treated with a progesterone-releasing device (PRID) for seven days: all responded to a second oestradiol treatment given 24 hours after removal of the PRID. Luteal cysts in three cows and follicular cysts in nine cows were ruptured manually: only one cow (a luteal case) responded to the second oestradiol treatment given 24 hours after manual rupture. In eight cows initially diagnosed with luteal cysts, cloprostenol was not given and plasma progesterone concentration at the time of oestradiol treatment was high (over 0.9 ng ml-1): none released LH in response to oestradiol. As manual rupture did not improve the LH response to oestradiol, it is concluded that the defective LH response to oestradiol in cows with cystic ovarian disease was not influenced in the short-term by cyst fluid contents.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Opioid involvement in LH release during the negative feedback effects of oestradiol and progesterone in dairy cows.

To create a clearly defined and uniform feedback phase of oestradiol, 1 mg oestradiol benzoate (OE2) was injected i.m. either 15-43 days post partum in 7 cows (Expt 1), or 12 h after prostaglandin oestrus synchronization of 4 cyclic cows (Expt 2 and 3). An endogenous opioid peptide (EOP) antagonist (250 mg naloxone), an EOP agonist (300 mg morphine), or a combination of the two was given in Expt 1, 2 and 3 respectively as a single i.v. injection in cows 16-18 h after OE2, i.e. in the negative feedback phase and before the expected onset of an induced luteinizing hormone (LH) surge. Blood samples were collected every 15 min for 1 h before and 2 h after each treatment. In Expt 1, naloxone failed to increase LH release when given during the negative feedback phase, but caused excessive release in one cow in which the LH surge had just begun. In all cows in Expt 2, morphine suppressed LH release (P less than 0.05). In Expt 3, naloxone prevented the suppressive effects of morphine for the first hour after treatment; a transient rise in LH occurred in one cow in which treatment was given 1 h before the start of the LH surge. In Expt 4, 250 mg naloxone was injected i.v. into 4 cows that had a plasma progesterone concentration of 1.5-3.1 ng mL-1 in the luteal phase of the oestrous cycle: naloxone failed to increase LH concentrations. It is concluded that LH can be further suppressed by opiates given to cows during the negative feedback phase of oestradiol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of prostaglandin F2 alpha on the fertility of dairy cows after calving.

Three hundred and thirty-one dairy cows in six herds were used to study the effect of a single injection of 25 mg dinoprost, a prostaglandin F2 alpha derivative, administered eight days after calving on several indices of fertility. A detailed comparison was made between 113 treated cows and 113 control cows of the same parity, which had calved within seven days of each other on the same farm and had experienced the same degree of dystocia. In cows which had calved without assistance, the treatment reduced the mean interval between calving and first heat from 40 days to 37 days but increased the mean interval between calving and conception from 83 days to 85 days. In cows which had required assistance at calving, the treatment reduced the mean interval between calving and first heat from 44 days to 34 days and reduced the mean calving to conception interval from 86 days to 68 days. The cows which benefited most were those which had required assistance during their second, third or fourth calvings; their calving to conception intervals were shortened by 22.5 days. An average of 1.39 services was required to establish conception in the treated cows which calved unaided, with 70 per cent conceiving to the first service, compared with an average of 1.34 services per conception and a 72 per cent conception rate to first service for their untreated herdmates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A survey of caesarean operations on cattle in general veterinary practice.

The animal most frequently requiring operation for dystocia in this survey of 133 cases was the Friesian/Holstein heifer. In 38 per cent of cases the reason for surgery was an oversized calf and in 84 per cent the operation was performed on the farm of origin. The majority of the dams were operated on while standing, using a left flank incision, and under paravertebral or field infiltration with local anaesthetic solution. Exteriorisation of the uterus did not appear to be essential except when the calf was dead. Ninety-five per cent of the calves alive in utero and 91 per cent of the dams survived, although 30 per cent of the dams suffered ill-health afterwards. In nine cases neither dam nor calf survived. The fertility indices of those which were rebred were not markedly affected, but milk production was reduced by an estimated 12 per cent of the potential yield.

Age Factors↗
PubMed1990

Effect of preslaughter experience on behaviour, plasma cortisol and muscle pH in farmed red deer.

Three groups of farmed red deer were shot in the field, three groups were slaughtered on the farm and three groups were transported to commercial slaughterhouses. The behaviour of the animals was observed and peripheral plasma cortisol concentrations were measured immediately after slaughter and neck muscle pH was measured 24 hours after slaughter. The deer could be handled and herded without agitation when only one unhindered direction was open to them and nothing in the environment caused alarm. Shallow angled loading ramps were preferable. Deer shot in the field and deer penned without handling had low average plasma cortisol concentrations (less than 7 ng/ml) and a muscle pH less than 5.74 whereas deer which had been herded on the farm, or transported to a slaughterhouse, had high cortisol concentrations (greater than 20 ng/ml) and a muscle pH above 5.74. However, only four of 66 male deer transported to a slaughterhouse had a muscle pH above 6.0, the pH associated with dark cutting meat in red deer.

Abattoirs↗
PubMed1990

The structure of the cervical canal of the ewe.

The cervical canal of the ewe does not allow for the consistent transcervical passage of insemination instruments. To define the factors affecting transcervical passage, the gross anatomy of the cervix and canal were studied in 100 estrous ewes and then in their reproductive organs following slaughter. In each ewe, the vagina and cervical opening was examined and the external os was classified into one of four types. Insemination instruments were introduced into the cervical opening and manipulation through the canal was attempted. Fluoroscopy was used to record the flow of contrast material through the canal. Ultrasound, xeroradiography and computed axial tomography were used to image the canal of the recovered reproductive tracts. Following imaging, each cervical canal was filled with silicone to create a mold which was used to measure and describe the canal. The average length (+/-SD) of the cervical canal was 6.7 +/- 1.1 cm and contained 4.9 +/- 1.0 funnel-shaped rings (n = 79). Successful passage of insemination instruments was limited by failure to identify the cervical opening and the small openings in the rings, 2.7 +/- 1.1 mm on average (+/-SD) which were not concentrically aligned. The eccentric rings were most consistently the second or third rings from the external os. The design of effective instrumentation and technique for transcervical passage must take these factors into account.

Journal Article↗