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Biomedical subjects

G A Anderson

Publications and source records attributed to G A Anderson.

At least 127 records · Page 7Linked to original sources
PubMed1983

Influence of acepromazine maleate on the equine haematocrit.

The effect of acepromazine maleate (ACP) on the equine venous haematocrit and total plasma protein concentration was studied in six clinically normal horses. Total plasma protein concentration was not appreciably influenced by ACP. However, the haematocrit decreased with the duration, but not the degree, of the decrease being dose-related. Mean haematocrit values returned to control levels by 12 h after 0.05 mg ACP/kg body weight and 21 h after 0.15 mg ACP/kg body weight.

Acepromazine↗
PubMed1983

Assessment of the efficacy of an abductor muscle prosthesis for treatment of laryngeal hemiplegia in horses.

Four variations of abductor muscle prosthesis for treating laryngeal hemiplegia were evaluated in 153 horses by questionnaire, and in the 100 Thoroughbred racehorses in this group survival analysis was used to compare their racing performances and earnings with those of 400 control horses. The questionnaire indicated that the technique which included a ventriculectomy and 2 prostheses was regarded as being the most successful (P less than 0.01) and resulted in the least residual stertor (P less than 0.001). Survival analysis showed that there was no significant difference between the treated group of horses and the control horses (P greater than 0.05).

Animals↗
PubMed1983

Prognosis in equine colic: a comparative study of variables used to assess individual cases.

The present retrospective study compared objectively the prognostic value of many variables routinely used in the assessment of equine colic cases. The best prognostic variables were those which assessed the integrity of cardiovascular function. Ranked in order of decreasing merit the following variables were able to discriminate between horses which lived and those which died: systolic pressure, blood lactate concentration, oral mucous membrane capillary refill time, diastolic pressure, arterial pulse amplitude, degree of mental depression, blood urea concentration, haematocrit, heart rate, haematocrit/plasma protein ratio, oral mucous membrane colour, jugular filling rate, frequency of gut sounds, differential blood leucocyte count, blood glucose concentration and respiratory rate. Assessment of systolic pressure alone appropriately classified the outcome (survival or death) of 86 per cent (64 out of 73) cases examined. Combined assessment of systolic pressure, blood lactate concentration, blood urea concentration and haematocrit permitted accurate classification of 93 per cent (68 of 73) of the cases examined. Outcome classification formulae for these four variables, alone and in all combinations, are presented.

Animals↗
PubMed1983

Assessment of the necessity for surgical intervention in cases of equine colic: a retrospective study.

The present study retrospectively examined clinical and clinicopathological findings in horses with colic to determine which variables distinguished between medically treatable cases and cases which required surgical intervention. Heart rate, haematocrit, haemoglobin concentration, blood erythrocyte count, frequency of borborygmi and degree of mental depression showed the greatest differences (P less than 0.001) between medical and surgical groups. However, some variables which primarily evaluated cardiovascular function, ie, blood pressure, oral mucosal capillary refill time and blood lactate concentration, were not significantly different between medical and surgical groups. When several of the following findings are observed together surgery is suggested: moderate to marked colic signs; tacky to dry oral mucosa which is discoloured (especially when brick-red or blue); decreased to absent borborygmi, probably associated with absence of rectal faeces; nasograstric intubation producing refluent fluid; leucocytosis with a left-shift; and tachypnoea, tachycardia, elevated haematocrit, hyperglycaemia and uraemia.

Animals↗
PubMed1983

Prognosis in equine colic: a study of individual variables used in case assessment.

The individual merit of the use of 43 variables to assess the prognosis of equine colic cases was examined. The following variables revealed highly significant (P less than 0.001) differences between cases which survived and those which died: blood pressure; heart rate; oral mucosal capillary refill time; degree of mental depression; venous haemoglobin concentration, haematocrit, erythrocyte count, urea concentration and lactate concentration; peritoneal fluid lactate concentration; and haematocrit/plasma protein and serum protein concentration ratios. Thus, in general, variables which assessed cardiovascular function were good prognostic guides.

Animals↗
PubMed1983

Suppressed release of LH in ovariectomized post-partum ewes.

The patterns of LH release were studied in 5 ewes, ovariectomized when 3 days post partum, at 4, 14, 33, 47 and 61 days after ovariectomy. These patterns were compared with those in 4 seasonally anoestrous (control) ewes ovariectomized and sampled at the same times. In the control ewes regular pulsatile release of LH was apparent 4 days after ovariectomy: plasma LH concentrations and LH pulse frequencies, but not pulse amplitudes, then declined. In the post-partum ewes all indices of LH release were lower than those in the control ewes at 4 days after ovariectomy, but then they increased: pulse amplitude was greater (P less than 0.05) at 14 days after ovariectomy, and plasma LH concentrations were greater (P less than 0.05, 0.01) at 14 and 33 days than in control ewes. These results indicate that the hypothalamopituitary axis of lactating ewes has a reduced capacity to release LH for only a short period after ovariectomy early in the post-partum period. This probably reflects the time needed for recovery from the inhibitory effects of ovarian and placental hormones, and may reflect reduced secretion of LH-RH.

Animals↗
PubMed1982

Pulmonary haemorrhage in standardbred horses after racing.

Endoscopic examinations of the upper respiratory tract were done on 92 of 314 Standardbred horses that raced one or more times at 4 consecutive, weekly race meetings. Although participation was voluntary, the characteristics of the population of horses examined were not statistically different from those of all horses that raced. No horse showed epistaxis, but 34 (32.4%) examinations of the trachea revealed blood that ranged from a trace in the tracheal mucus to large amounts scattered over the tracheal walls. Forty-four horses exhibited minor degrees of pharyngeal lymphoid hyperplasia, 2 had asynchronous movement of the left arytenoid cartilage and 15 had grains of sand in the respiratory tract. There was no association between bleeding and age, sex, distance of race, place in race or date of race. Mucus and mucopurulent material occurred less often after longer races and more often on the last 3 race nights.

Age Factors↗
PubMed1982

Hypotension in the horse induced by acepromazine maleate.

The hypotensive effect of acepromazine maleate was related to both the dose and route of administration. The degree and duration of hypotension varied between individual horses. In general, intravenous administration produced a more rapid maximum effect than intramuscular injection and the larger the dose the longer blood pressure remained at low levels. Average systolic pressure (of 6 horses) remained significantly below control values for more than 6 h after an intramuscular injection of 0.05 mg acepromazine maleate/kg body weight. Respiratory rate was markedly decreased, with the duration, but not the degree of bradypnoea related to the dose administered. A slight, transient decrease in body temperature was observed. Heart rate was not significantly influenced by administration of acepromazine maleate.

Acepromazine↗
PubMed1982

Correct occlusive bladder width for indirect blood pressure measurement in horses.

The influence of occlusive bladder width on blood pressure, measured indirectly using a doppler ultrasound technique at the middle coccygeal artery, was studied in 6 anesthetized horses. The relationship was investigated on tails with and without hair, and the optimum bladder width (BW)/tail girth (TG) ratio was determined for systolic pressure (SP) and diastolic pressure (DP), with the data grouped as unclipped tails (TT-1), clipped tails (TT-2), and both unclipped and clipped tails collectively (TTB). The optimum BW/TG ratios for SP and DP were 0.296 and 0.866 for TT-1, 0.376 and 1.156 for TT-2, and 0.339 and 0.983 for TTB, respectively. Despite the differences in optimal BW/TG ratios between TT-1 and TT-2, their regression equations were not significantly (P less than 0.05) different and therefore, data could be considered as TTB. The regression equations for TTB showed that a BW/TG ratio of 0.482 underestimated SP and overestimated DP by approximately 8.8%. In mature Thoroughbreds (mean TG 21.5 cm), this value corresponded to a BW of 10.4 cm. Blood pressure measured directly in the greater metatarsal artery was significantly different from that measured directly in the middle coccygeal artery in individual horses, but when averaged over all horses, there was no significant difference between the 2 sites.

Animals↗
PubMed1981

The failure of prolactin to enhance the inhibitory effect of oestradiol-17 beta on LH synthesis and release in ewes.

Groups of 5-6 ovariectomized ewes were treated with oestradiol-17 beta (100 mg implant) and/or bromocriptine (1 mg; 2 X daily) or with vehicle for 30 days during the anoestrous season. Oestradiol increased (P less than 0.05) the priming effect of 2 X 1 micrograms LH-RH on LH release and decreased (P less than 0.001) pituitary LH content, plasma LH levels, the frequency and amplitude of pulsatile LH release and the LH response to LH-RH. Bromocriptine decreased prolactin levels to less than 2.5 ng/ml (P less than 0.001) and increased the LH response to LH-RH (P less than 0.05). There were no significant treatment interactions. It is concluded that prolactin does not enhance the inhibitory effect of oestradiol on LH synthesis and release in the ewe.

Anestrus↗
PubMed1980

Extensions to a veterinary health and management program data system for dairy herds.

This paper reports additions to our previously described veterinary health and management program for dairy herds. These include a graphical representation of mean milk production per cow per day, a current and historical record of the distribution of the herd in reproduction states, a standardised index of clinical mastitis and an index of the degree of nutritional anoestrus in a herd. For seasonally-calving herds, new categories of cows requiring examination or consideration have been added to selection lists. These are cows which have no oestrus recorded for 30 days preceding a nominated date for the commencement of breeding and those which have no oestrus recorded for 30 days after the nominated date.

Animals↗
PubMed1980

The effect of variations in the interval between calving and first service on the reproductive performance of normal dairy cows.

Reproductive records from 8 commercial dairy herds in a herd health scheme were examined to determine the effect of the calving to first service interval on breeding performance. A reduction in the first service conception rate was observed in cows bred within 60 days of calving. Early breeding did not appear to have any adverse effect on subsequent reproductive performance. A linear relationship between days to first service and intercalving interval was demonstrated. A 1-day reduction in the interval to first service reduced the intercalving interval by 0.86 of a day. This paper shows that a reduction in calving to service intervals to achieve annual calving produces high economic gains.

Animals↗
PubMed1978

Pregnancy rates and non-return rates following artificial and natural breeding in dairy herds.

Information routinely supplied during the conduct of a dairy herd health program was analysed to evaluate the performance of artificial breeding in Victoria. A comparison was made between 60 to 90-day non-return rates (supplied by artificial breeding centres) and pregnancy rates (determined by manual pregnancy diagnosis) for first artificial inseminations in 108 herd years in which both items were available in the 1973 and 1974 breeding seasons. The values were 69.3% and 58.2% respectively (P less than 0.001). Non-return rates and conception rates were found to decline as herd size increased. Pregnancy rates to first artificial and natural services did not differ significantly from each other but pregnancy rates were significantly more variable to natural than artificial service (P less than 0.001). The mean pregnancy rate to artificial insemination for all herd years studied was 57.5% and the pregnancy rate to natural service was 58.0%.

Animals↗