Hematologic, iron-related, and acute-phase protein responses to sustained strenuous exercise.

This study was undertaken to gain insight into the mechanisms responsible for the hypoferremia occurring after severe exercise. To this end, 18 athletes who were competing in a 160-km triathlon involving canoeing, cycling, and running were evaluated before the race, immediately after the finish, and thereafter at 30 min, 24 h, and 48 h. The evaluation included plasma iron, total iron-binding capacity, lactoferrin, ferritin, haptoglobin, cortisol, various enzymes, and white cell count. The cortisol, white cell count, and lactoferrin were significantly increased immediately after the race, while the plasma iron and transferrin saturation were significantly decreased. There was a 40% but nonsignificant rise in the plasma ferritin at the completion of the race, while the C-reactive protein was raised by nearly 300% at 24 h. In contrast, haptoglobin declined significantly by 24 h but was normal again 24 h later. Quantitative considerations suggested that the lactoferrin was not responsible for removing transferrin iron from circulation and hence causing the hypoferremia. Instead, it seemed more likely that the iron-related changes were occurring as part of an acute phase response initiated by muscle injury.

Stress in cattle assessed after handling, after transport and after slaughter.

Blood samples were collected from unstressed cattle and from cattle undergoing handling stress, transport stress and slaughter. The blood was analysed for ACTH, cortisol, thyroxine stimulating hormone, tri-iodothyronine (T3) and catecholamine concentrations, and for haematocrit, total plasma protein, plasma lipid, lactate and glucose concentrations. Compared to control values handling significantly increased T3, cortisol, lipid and lactate concentrations. Compared to handling, transport stress was associated with increased catecholamines and lactate concentrations, a decreased cortisol concentration and similar concentrations of T3, lipid and glucose. Compared to transport, slaughter resulted in high catecholamines, lactate and glucose, and low T3, cortisol and lipid levels. It is concluded that the response to stress has two phases, a hypothalamic-adrenal cortex phase which is associated with perceived environmental stress such as noise, and a sympathetic-adrenal-medulla phase which is associated with neurogenic stress such as transport or specifically the massive sympathetic discharge caused by stunning. Combinations of stresses produce a mixed response.

The measurement of psychophysiological reactions of pilots to a stressor in a flight simulator.

Seventeen Boeing 737 pilots were exposed to an acute stressor in a flight simulator: a birdstrike between V1 (velocity of aircraft on take-off run at which crew is committed to take-off regardless of any incidents occurring) and VR (velocity of aircraft at take-off). Certain physiological variables together with state anxiety scores were measured at different stages of the simulated flight. Levels of plasma cortisol, norepinephrine, total protein, total lipid, lactate, and the haematocrit changed significantly across the test conditions. Plasma epinephrine, osmolality and glucose levels did not change significantly across the test conditions. Captains and copilots differed significantly in the profiles obtained for the state anxiety scores. The variables measured in this study demonstrated different profiles in response to the stressor. Conceptual and methodological problems need to be solved before an integrated psychophysiological approach to the reactions of pilots to stressors can be developed.

Blood constituent responses of cattle to herding.

Blood was obtained over a period of 20 minutes by remote controlled procedures from cattle while they were herded. Samples were analysed for catecholamines, cortisol, haematocrit, total lipid, glucose and lactate. The results show that the response to a given stressor is specific and suggest that multiple stressors may not necessarily result in additive effects.

Effects of chemical immobilisation on the blood composition of impala (Aepyceros melampus (Lichtenstein).

The effects of chemical immobilisation on impala (Aepyceros melampus) were investigated. The results indicate that etorphine HCl or Carfentanil should not be used in isolation but that xylazine should be included in the immobilisation "cocktail". The highest dose possible, commensurate with safety, should be used in order to minimise time and distance to recumbency. Body temperature should be monitored and if cooling measures are not effective the animal should be aroused. Either diprenorphine HCl alone or in combination with yohimbine and 4-aminopyridine should be used as antidote/s.

The composition of plasma and interstitial fluid of goats with swelling disease.

Angora goats may develop a characteristic ventral oedema of the subcutaneous tissue which is not unlike the 'wet-carcass syndrome' of sheep. The plasma of oedematous goats shows a lower total protein concentration, a lower colloid osmotic pressure and a lower albumin: globulin ratio than that of normal goats. Similarly, interstitial fluid of oedematous goats has a lower protein concentration, osmolality and colloid osmotic pressure than the fluid from normal but a similar albumin:globulin ratio. These results suggest that, unlike the 'wet-carcass syndrome' of sheep, the most likely explanation for the oedema is hypoproteinaemia which leads to filtration of fluid and an increased capillary permeability.

The composition of plasma and interstitial fluid of sheep with the 'wet carcass' syndrome.

Carcasses of sheep from various areas in South Africa and South West Africa (Namibia) show a wet glistening appearance immediately after slaughter. The subcutaneous interstitial fluid of these sheep has a significantly lower protein concentration and colloid osmotic pressure and a significantly higher albumin/globulin ratio than that of normal sheep. These results imply the presence of an oedema and an increased capillary permeability to protein. They suggest that histamine, or an histamine-like substance, mediates the changes.

Necropsies of eight horses infected with Strongylus equinus and Strongylus edentatus.

Ponies (n = 8) approximately 18 months old, were infected with 20,000 to 30,000 infective larvae of Strongylus equinus with less than 10% contamination with Strongylus edentatus larvae and necropsied 7 months post-infection. Lesions were present in the omentum, liver, pancreas, ventral colon, caecum and occasionally in the lungs. There were numerous intraabdominal adhesions and severe multiple granulomatous omentitis. Pancreatic damage, which characterises S. equinus, was exceptionally mild and was manifested mainly by slight periductular infiltration of eosinophils. Granulomas associated with larvae were found in the connective tissue associated with the pancreas. Larvae were recovered from the flanks, the peritoneum, the caecum and the kidney. Larval recovery was low, with a high percentage of the total number of larvae recovered in some of the carcasses being S. edentatus.

Arterial blood gas composition, consciousness and death in rabbits.

Conscious rabbits were exposed to environments with low oxygen and/or high carbon dioxide. The electroencephalogram and arterial blood pressure were recorded. Arterial blood samples were taken sequentially. Rabbits became 'unconscious' at an arterial blood PO2 of 25 +/- 1 mm Hg and PCO2 of 99 +/- 27 mm Hg, when simultaneously the environmental oxygen was decreased and carbon dioxide increased. Brain death occurred at a PO2 of 23 +/- 1 mm Hg and PCO2 of 113 +/- 32 mm Hg. Cerebral perfusion was still adequate. In rabbits, the margin between 'unconsciousness' and 'death' is narrow so far as PO2 is concerned. If these results apply generally, animals culled with muscle relaxants may perceive stress involved until shortly before death.

Factors which affect blood variables of slaughtered cattle.

Blood was obtained at an abattoir from 4 groups of cattle. The first group was slaughtered in a conventional way, the second and third were subjected to shechita slaughter with or without the application of the captive bolt immediately after the cutting of the throat, and the fourth group of cattle was subjected to a period of recumbency prior to conventional slaughter. Blood samples were analysed for concentrations of catecholamines, cortisol, glucose, lactate and total lipids. The haematocrit and osmolarity was also determined. There were no major differences in the blood variables of cattle subjected to conventional slaughter and those of cattle which had been subjected to a period of recumbency prior to conventional slaughter. Plasma catecholamine concentrations in cattle subjected to shechita slaughter without the application of a stun, were significantly elevated when compared to any of the other groups. It was concluded that postural changes have very little effect on the blood variables, but that the application of a stun after the throat has been cut in shechita slaughter abolishes the increases in blood variables associated with shechita in the absence of stunning.

Blood constituent responses of animals culled with succinyldicholine and hexamethonium.

Blood constituent responses of elephants and buffaloes culled in the Kruger National Park, using a mixture of succinyldicholine and hexamethonium, were compared to those of animals culled with succinyldicholine only. The results show a decreased physiological response in the animals culled with the mixture, characterised by lower total catecholamine, cortisol and glucose concentrations. Neither a delay of up to 30 min in obtaining blood samples from culled animals, nor a delay of up to 30 min in processing samples obtained immediately after cessation of respiration, gave any significant difference in the blood constituents which were measured.

Plasma constituents in Nguni cows over forty-eight hours.

Plasma constituents were investigated at ninety minute intervals over a forty-eight hour period on four unrestrained Nguni cows (in small cubicles) in order to study the presence or absence of rhythms. No circadian, ultradian or diurnal rhythm was found for any of the parameters investigated. Basal values over a forty-eight hour period were obtained for certain plasma constituents. These values are of use for studies relating to the effects of stress in cattle.

The response of animals to suxamethonium (succinyldicholine) and succinylmonocholine.

The time which elapses before cessation of breathing, and blood pressure and blood gas changes after the intramuscular administration of suxamethonium, or a mixture of suxamethonium and hexamethonium, is compared in immobilised African elephants (Loxodonta africana) and buffaloes (Syncerus caffer). In addition, the respiratory responses of elephants and other animals to intravenous administration of suxamethonium and succinylmonocholine are reported on, as are the effects of darting animals with succinylmonocholine. The results show that respiration is affected in a similar fashion in all species investigated. However, the characteristic gradual decrease in respiratory rate seen in elephants during culling, using suxamethonium, resembles the effects observed when succinylmonocholine is administered. It is suggested that elephants are killed by this first breakdown product of suxamethonium during culling and/or that unique acetylcholine receptors may be involved.

Effect of a 72 hour fast on physiological stress indicators in feedlot cattle.

Feedlot oxen (n = 15) were herded and subjected to venepuncture on a daily basis for 2 weeks. Plasma glucose, lactate, free fatty acids, total lipids, total protein, cortisol, catecholamines, osmolarity and haematocrit were compared between Days 1 and 14. Plasma glucose concentration and haematocrit decreased significantly while total plasma lipid and free fatty acid concentrations increased significantly over the 14 d. Thereafter, food was withdrawn for 72 h from the experimental group (n = 10) and the same blood variables were compared in the control and the experimental groups. Plasma free fatty acid concentrations rose, while glucose concentrations declined in the experimental group during the fasting period. It is concluded that food deprivation for 72 h in cattle cannot be regarded as a major stressor.

Blood composition in culled elephants and buffaloes.

Blood composition of succinyldicholine culled elephants and buffaloes was compared with that of undisturbed animals shot in the brain. The results show statistically significant differences in a number of variables including plasma ACTH and cortisol concentrations. The observed changes are attributed to stress induced by a combination of herding and darting with succinyldicholine and asphyxia. Extrapolation from blood oxygen tensions suggests that this stress may be perceived for an undetermined period which is probably longer in elephants than buffaloes.