Differences in polymorphonucleocyte function and local inflammatory response between horses and ponies

REASONS FOR PERFORMING STUDY: Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response. HYPOTHESIS: That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies. METHODS: PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFalpha, IL-1, IL-6 and chemoattractants were determined. RESULTS: In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL-1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies. CONCLUSIONS: This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair. POTENTIAL RELEVANCE: Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine.     

Experimental vascular graft for liver transplantation

Hepatic artery thrombosis is a major cause of graft failure in liver transplantation. Use of donor interponates are common, but results are controversial because of necrosis or thrombosis after rejection. Reperfusion injury, hypoxia and free radical production determinate the survival. The aim of the study was to create an 'ideal' arterial interponate. Autologous, tubular graft lined with mesothelial cells, prepared from the posterior rectus fascia sheath, was used for iliac artery replacement in eight mongrel dogs for six months under immunosuppression. Patency rate was followed by Doppler ultrasound. Eight grafts remained patent and another two are patent after one year. The patency rate was good (median Doppler flow: 370 cm/sec) and there was no necrosis, thrombosis or aneurysmatic formation. The grafts showed viable morphology with neoangiogenesis, appearance of elastin, smooth muscle and endothelial cells. Electron microscopy showed intact mitochondrial structures without signs of hypoxia. Tissue oxygenation was good in all cases with normal (< 30 ng/ml) myeloperoxidase production. In conclusion, this autologous graft presents good long-term patency rate. Viability, arterialisation and low thrombogenicity are prognostic factors indicating usability of the graft in the clinical practice without the risk of rejection. Further investigations such as cell cultures and standardisation are necessary.     

Study of the clinical effects of postoperative parenteral nutrition in 15 horses

Several clinical variables were compared in two groups of 15 horses recovering from resection and anastomosis of a strangulated small intestine; 15 were treated with parenteral nutrition and 15 were starved routinely. There was some evidence that parenteral nutrition had a short-lived adverse effect on both the catheter sites and gastric emptying, but there were no marked adverse clinical effects and no evidence of any improvement in the horses' condition.     

Catheters: a review of the selection, utilisation and complications of catheters for peripheral venous access

Intravenous catheters are used for the administration of medications and fluids and are an integral part of veterinary practice. The aim of catheter use is to optimise administration of medication and minimise complications such as thrombus formation, thrombophlebitis and sepsis. Catheters made from teflon are less flexible, less durable and stimulate more tissue reaction than polyurethane or silicon. However silicon catheters are more expensive and complicated to insert. Generally, for veterinary practice, the biostability and cost of polyurethane catheters make them preferable for short and long-term use. The smallest diameter catheter should be selected to minimise internal vessel wall contact and irritation without compromising medication delivery. The site of insertion varies with individual preference, vessel access and patient compliance. The jugular, cephalic, saphenous, ear, lateral thoracic and subcutaneous abdominal veins are accessible. Hair removal and a thorough aseptic skin preparation should be performed prior to catheter insertion. Daily maintenance is required to detect complications and maximise catheter longevity. Potential complications include thrombus formation, thromboembolism, bacterial colonisation and septicaemia, blood loss and air embolism. Permanent or transient skin dwelling bacteria are commonly isolated if sepsis occurs. The development of novel antiseptic and antibiotic impregnated catheters may reduce the complications associated with catheter infection in the future.     

Effects of alpha-tocopheryl acetate supplementation and salt addition on the oxidative stability (TBARS) and warmed-over flavour (WOF) of cooked turkey meat.

1. Day-old turkey poults (n = 14) were randomly divided into 2 groups (n = 7) and fed diets containing 20 (E20) and 600 (E600) mg all-rac-alpha-tocopheryl acetate/kg food for 21 weeks prior to slaughter. Following slaughter, breast and leg meat was removed and 4 batches of patties were produced from each. Two of the batches were formed from E20 meat (E20) and E20 plus 1% salt (E20S). Two similar batches were formed from E600 meat (E600) and E600 plus 1% salt (E600S). 2. Patties were fried, cooled and overwrapped with high oxygen-permeable film. Overwrapped patties were displayed in a 4 microC cabinet under fluorescent light (616 lux). Lipid oxidation (TBARS numbers) was determined on d 0, 2, 4, 6, 8 and 10, while taste panels to assess warmed-over flavour (WOF) were carried out on d 0, 2 and 4 of refrigerated (4 degrees C) display. 3. In the case of both leg and breast meat, E600 patties were the least susceptible of the 4 treatment batches to lipid oxidation. Salt had the effect of promoting lipid oxidation, with E20S and E600S patties having higher TBARS numbers than the corresponding patty batches where salt was absent. 4. Taste panel results showed that leg and breast patties formed from the meat of turkeys given alpha-tocopheryl acetate enriched diets developed significantly (P < 0.05) less WOF than those formed from control turkey meat on d 2 and 4 of refrigerated (4 degrees C) display. Patties containing 1% salt generally exhibited a greater degree of WOF than patties without salt. 5. A linear relationship was observed between TBARS numbers and WOF percentages for all batches of leg and breast patties.     

Heligmosomoides polygyrus and Trypanosoma congolense infections in mice: effect of immunisation by abbreviated larval infection.

Concurrent African trypanosome and gastrointestinal helminth infections are prevalent in sub-humid savannah where they are endemic. However, acquired resistance in animals varies with their responder status and exposure. As a guide to study in the definitive hosts, the effects of Trypanosoma congolense infection on the development and maintenance of homologous Heligmosomoides polygyrus resistance were investigated in outbred TO mice. These mice were immunised by abbreviation of larval infection. Immune or naive mice were either infected with 500 infective larvae (L3) of H. polygyrus and/or 10(4) bloodstream forms of T. congolense or were not infected. The outcome of infection was monitored by routine parasitological and immunological techniques for 30 days after the day of the T. congolense infection. Significantly more immune mice concurrently infected with both parasites survived than did immune mice in which H. polygyrus was superimposed on a 10-day-old T. congolense infection. Although all the mice in this latter group died before the end of the experiment, larval immunisation prolonged their survival, relative to similarly treated naive mice. The antibody titres to H. polygyrus in the sera of immune mice challenged with H. polygyrus alone were significantly higher than those of immune mice concurrently infected with both parasites but the levels of protection obtained were comparable. It is concluded that T. congolense may not completely block the strong acquired resistance induced by abbreviated H. polygyrus larval infection in TO mice but is capable of interfering with protective responses, especially if the trypanosome infection occurs prior to H. polygyrus challenge infection.     

Effect of timing and size of photoperiod change on plasma FSH concentration and the correlation between FSH and age at first egg in pullets.

1. ISA Brown pullets were transferred at 6, 9, 12, 15, 18 or 20.3 weeks of age from an 8 h photoperiod to an 8, 10, 13 or 16 h photoperiod. Plasma follicle stimulating hormone (FSH) concentration was measured at transfer at 7 and 14 d afterwards, and age at first egg (AFE) was recorded. 2. Plasma FSH concentration in pullets reared on constant 8 h photoperiods generally increased with age but with a trough at 12 weeks. Plasma FSH increased during the first 14 d of photostimulation to a significantly higher concentration, compared with constant 8 h controls, when the photoperiod was increased to 13 or 16 h at 9, 12 or 15 weeks; but for the increase from 8 h to 10 h photoperiods FSH was only significantly higher than controls when the change was made at 12 weeks. 3. The change in plasma FSH concentration 14 d after photostimulation was significantly correlated with mean AFE (reported in Lewis et al., 1997) and appears to be a better predictor of gonadal development than concurrent changes in plasma LH concentration previously reported (Lewis et al., 1994).     

Persistent activity of doramectin injectable formulation against experimental challenge with Haemonchus placei in cattle.

Two studies were conducted in North America to evaluate the persistent activity of doramectin injectable formulation against experimental challenge with Haemonchus placei. In both studies, calves were randomly assigned to 1 of 4 treatment groups (n = 10 per group) or a larval viability group (n = 2). Calves were treated subcutaneously in the lateral midline of the neck with saline (1 ml/50 kg) on Day 0, or with doramectin (200 mg/kg = 1 ml/50 kg) on Day 0, 7, or 14. Animals used to assess larval viability did not receive any treatment. Beginning on Day 14 and continuing through Day 28, each of the 40 treated calves were given approximately 300 infective larvae of H. placei per os. The two larval viability animals received approximately 10,000 larvae as a single dose on Day 28. Approximately two weeks later, all animals were slaughtered and the abomasum from each calf processed for nematode recovery. A 2% aliquot of abomasal contents plus wash was examined for enumeration and identification of nematodes. Geometric mean H. placei counts were calculated from the log (H. placei count +1) and used to estimate percentage reduction. Overall, doramectin was > or =96.9% efficacious in reducing infection with H. placei when challenged daily 14-28 days after treatment.     

Survival of Salmonella in the crop contents of market-age broilers during feed withdrawal.

Recent studies have indicated that crop contamination increases during preslaughter feed withdrawal and that contaminated crop contents may serve as an important source of Salmonella entry into poultry processing plants. During the present study, we evaluated the effect of preslaughter feed withdrawal on crop pH and Salmonella crop contamination in broilers from three commercial broiler flocks. The effect of experimental feed withdrawal on crop pH, lactic acid concentration, and Salmonella crop contamination was also evaluated in market-age broilers challenged experimentally with Salmonella typhimurium. Crop pH increased significantly (P < 0.05) from 3.64 +/- 0.25 before feed removal to 5.14 +/- 0.72 after 8 hr of feed withdrawal in broilers from commercial flocks. The incidence of Salmonella crop contamination in the commercial broilers increased (P < 0.05) from 3.3% before feed removal to 12.6% after 8 hr of feed withdrawal. Similarly, crop pH increased (P < 0.05) by a magnitude of approximately 1 unit in broilers after 8 hr of experimental feed withdrawal. The population of S. typhimurium in the crops of the experimentally challenged broilers increased (P < 0.05) by approximately 1 log unit during the 8-hr experimental feed withdrawal. The concentration of lactic acid in the crop of the broilers during experimental feed withdrawal decreased (P < 0.01) from a range of 119-135 mumol/ml before feed removal to a range of 22-32 mumol/ml after 8 hr of feed withdrawal. The results indicated that feed withdrawal resulted in a decrease in lactic acid in the crop, accompanied by an increase in crop pH, and an increase in Salmonella crop contamination.