Elastase-producing microorganisms in horse lungs: their possible role in the pathogenesis of chronic pulmonary disease in the horse

Seventeen out of 21 horses had pulmonary microbial organisms which reached considerable numbers in seven cases. Elastase-producing microorganisms from the environment (Streptomyces species and to a lesser extent Bacillus species) constituted 22 per cent to 99 per cent (mean 79 per cent) of the total growth. There was a considerable number of microorganisms with in vitro-produced elastases which were not or only slightly affected by horse serum. There was no correlation between numbers of organisms and pulmonary histopathological findings thus the significance of these microorganisms in the pathogenesis of alveolar emphysema is unknown. The growth of a strain of Streptomyces collinus/diastatochromogus isolated from the lungs was suppressed by fresh horse serum but not by decomplemented horse serum. Complement activation in response to this organism could contribute to airway inflammation through the production of mediators.     

Pharmacological experiments as a basis for the administration of digoxin in the horse.

It is shown that the concentration of ouabain necessary for 50 per cent inhibition of the Na+K activated membrane ATPase of red cells is similar in man and horse. This is taken to indicate that the two species have similar sensitivity towards cardiac glycosides in general. In five adult healthy horses plasma digoxin concentration was measured with a radioimmunoassay technique after a single intravenous injection of 1 mg/100 kg body weight digoxin. The half time of elimination was 23 h and the apparent volume of distribution 7.3 litres/kg. An approximate estimate of plasma protein binding of digoxin was obtained by measuring digoxin with a fluorimetric assay in the ultrafiltrate from horse plasma containing 2-20 mug/ml. At concentrations below 10(-5)(g/ml 20 to 40 per cent of digoxin present in horse plasma is bound to protein. With this information and by using effective digoxin concentration measured in humans an average daily maintenance dose of 0-5-0-75 mg/100 kg body weight was calculated which may serve as a guideline in the treatment of congestive heart failure with digoxin in the horse.     

Breed and species comparison of amino acid transport variation in equine erythrocytes

The amino acid permeability of red blood cells from Equus caballus (thoroughbred, Arab, shire and pony), E przewalskii (Przewalski's horse), E asinus (donkey and mule) and E burchelli (common or plains zebra) was measured. Individual animals exhibited stable but widely differing rates of L-[U-14C]alanine uptake in the range 5 to 1554 mumol (litre cells)-1 h-1 (0.2 mM extracellular L-alanine, 37 degrees C). Of the thoroughbreds tested, 30 per cent had red blood cells which were essentially impermeable to L-alanine (5 to 10 mumol (litre cells)-1 h-1, giving transport rates similar to those found previously in amino acid transport-deficient sheep erythrocytes. In contrast, only 3 per cent of the ponies tested had red blood cells impermeable to L-alanine. No cases of erythrocyte amino acid transport deficiency were found in the other horse breeds and species tested.     

Experimental stimulation of eosinophil production in the domestic fowl (Gallus gallus domesticus)

A method has been devised to produce eosinophilia in birds experimentally. Multiple intraperitoneal injections of bovine serum albumin (BSA) produced a greater response than horse serum in young adult fowls, and injections of 2 ml BSA were more effective than injections of 0.2 ml. The highest eosinophilic responses were obtained with injections of BSA together with aluminium hydroxide. Thymectomy had little effect on eosinophil numbers following horse serum injections but irradiation produced a depressed response. Horse serum that had been heated to 56 degrees C for 30 minutes to inactivate complement and to denature proteins, including possible horse IgE, induced an eosinophilic response in 50 per cent of birds compared with only 14 per cent with unheated horse serum. Furthermore, when the former birds were reinjected after a rest period of 13 weeks, the eosinophilic response followed a similar curve as before but a higher proportion of birds responded. Birds aged over two years did not give a good eosinophilic response after horse serum stimulation. There was no consistent correlation between raised IgE levels and eosinophil numbers. Tolerance to horse serum was detected in some birds using a radial immunodiffusion technique. Analyses of blood plasma from birds with eosinophilia showed a significant increase in total amino acids compared with normal birds.     

Acute phase response in horses: changes in plasma cation concentrations after localised tissue injury

An acute phase reaction was elicited in four horses to which Freund's adjuvant was administered intramuscularly. The localised inflammation was accompanied by changes in the plasma concentrations of copper, iron and zinc. The plasma copper concentration, the plasma ceruloplasmin copper concentration and the ceruloplasmin oxidase activity in the plasma steadily increased to a maximum 24 days after the administration of the adjuvant. At this time, the plasma copper concentration was 2.2 micrograms/ml, a 90 per cent increase over the baseline concentration. The ratio of the concentration of plasma ceruloplasmin copper to plasma copper remained constant, indicating that the non-ceruloplasmin bound copper component of the plasma is also an acute phase reactant in the horse. The plasma zinc and iron concentrations decreased to 59 per cent and 30 per cent of their respective baseline concentrations and the severity of the inflammation appeared to influence the plasma concentrations of each metal. Weak correlations between the plasma fibrinogen concentration and the plasma copper and zinc concentrations of 25 horses with plasma fibrinogen concentrations of 5 g/litre or greater indicated that a single measurement of plasma copper concentration is not useful in the diagnosis of non-specific inflammatory disorders of the horse. However, the results suggest that the plasma copper concentrations in serial samples may be used to monitor the resolution of inflammatory disorders in the horse.     

Studies on the incorporation of 14 C-labelled amino acids into egg proteins

The incorporation of ¹⁴C‐labelled amino acids into egg white and yolk proteins has been studied. When the labelled amino acids were given intravenously as a hydrolysate of [U‐¹⁴C]‐protein from Chlorella, 10 per cent and 7 per cent of the ¹⁴G were recovered in the whites and yolks respectively of the first nine eggs laid. Differences in the specific activities of the conalbumin, the ovalbumins, ovomucoid, “postalbumins “ and lysozyme, isolated from the first active egg, were related to differences in amino acid composition. The specific activity of each amino acid prepared from the proteins was similar between different proteins, although within each protein specific activities of different amino acids varied widely. The proportionate rate of decrease of specific activity in the plasma of amino acids essential for egg production (except glycine) was constant or almost so, but it rapidly decreased for the non‐essential ones (except serine and proline). The specific activities of the amino acids, excepting aspartic and glutamic acids, in each protein were proportional to their mean specific activities in the plasma throughout the 24‐h period in which the egg white proteins were synthesised. It is concluded that these different proteins are synthesised from a shared amino acid pool, derived from plasma, at a rate which probably remains constant throughout the egg‐laying cycle and which is proportional to their content in the albumen.     

Sentinel practice-based survey of the management and health of horses in northern Britain.

Details of the management, feeding, level of activity and routine health care of horses in Scotland and the five northernmost counties in England were recorded through a stratified random sample of horse owners who had responded to a previous survey. Sixty-eight per cent of the horses were kept where their owners resided, and 32 per cent were kept away from the owner's home. More than 99 per cent were turned out to grazing for at least part of the year and 81 per cent were stabled for at least part of the time, most commonly bedded on straw (50 per cent) or shavings (34 per cent). Hay was fed to 87 per cent, sugar beet pulp to 64 per cent and commercially prepared concentrate mixes to 60 per cent of the horses. Hacking was the most popular activity (52 per cent of horses) followed by riding/pony club events (28 per cent) and showing (21 per cent). The majority of the horses were involved in more than one activity. There were an estimated 0.88 veterinary visits per horse per year and 29 per cent of the horses were reported to suffer from at least one permanent or recurrent health disorder. The median annual numbers of administrations of vaccines (influenza and tetanus) and anthelmintics were one and seven respectively per horse, and each horse was shod a median seven times. There were significant differences in the management of horses kept in different types of premises and in areas of different human population density.     

Effect of submaximal exercise on horse homocysteinaemia: possible implications for immune cells

Physical exercise induces a reduction of immune defences and an imbalance of red-ox status. In this study plasma levels of cysteine and homocysteine (Hcy) were determined in horses before and after submaximal treadmill exercise as well as the effect on horse lymphocyte proliferation. The exercise induced a significant increase in plasma Hcy levels, which remained high both after the 20 min recovery period and after 2 h of rest. Moreover, a reduction of lymphocyte responsiveness to the proliferative stimulus induced by Concanavalin A was observed. The effects of different Hcy concentrations on the proliferative capacity of lymphocytes in culture were also tested. The results indicated that 10 microM of this amino acid can reduce the proliferative capacity of resting lymphocytes as well as their responsiveness to mitogen. Moreover, our results suggest that homocysteinaemia could be considered one of the parameters affected by physical exercise in horses and that this amino acid could be implicated in the effects of physical exercise on the immune system.     

Black rhinoceros (Diceros bicornis) and domestic horse (Equus caballus) hindgut microflora demonstrate similar fermentation responses to grape seed extract supplementation in vitro

The domestic horse is used as a nutritional model for rhinoceros maintained under human care. The validity of this model for browsing rhinoceros has been questioned due to high prevalence of iron overload disorder (IOD) in captive black rhinoceros (Diceros bicornis), which is associated with high morbidity and mortality. Iron chelators, such as tannins, are under investigation as dietary supplements to ameliorate or prevent IOD in prone species. Polyphenolic compounds variably affect microbial fermentation, so the first objective of this experiment was to evaluate the effects of grape seed extract (GSE; a concentrated source of condensed tannins; CT) on black rhinoceros hindgut fermentation. Equine nutrition knowledge is used to assess supplements for rhinoceros; therefore, the second objective was to evaluate the domestic horse model for black rhinoceros fermentation and compare fermentation responses to GSE using a continuous single‐flow in vitro culture system. Two replicated continuous culture experiments were conducted using horse and black rhinoceros faeces as inoculum sources comparing four diets with increasing GSE inclusion (0.0%, 1.3%, 2.7% and 4.0% of diet dry matter). Diet and GSE polyphenolic compositions were determined, and sodium sulphite effect on neutral detergent fibre extraction of CT‐containing forages was tested. Increasing GSE inclusion stimulated microbial growth and fermentation, and proportionally increased diet CT concentration and iron‐binding capacity. Horse and black rhinoceros hindgut microflora nutrient digestibility and fermentation responses to GSE did not differ, and results supported equine fermentation as an adequate model for microbial fermentation in the black rhinoceros. Interpretation of these results is limited to hindgut fermentation and further research is needed to compare foregut digestibility and nutrient absorption between these two species. Supplementation of GSE in black rhinoceros diets up to 4% is unlikely to adversely affect hindgut nutrient digestibility or microbial viability and fermentation.     

Radioimmunoassay of thromboxane B2 in horse plasma

A radioimmunoassay for thromboxane B2 (TXB2) in unextracted horse plasma was evaluated. Sensitivity of the assay was 14.0 (SD 5.6) pg ml-1 of plasma. Interassay and intra-assay variation were 21.3 per cent and 4.3 per cent, respectively. The percentage of tracer bound in unextracted plasma in the absence of TXB2 was often higher than that in buffer. Therefore standard curves were obtained using standards diluted in plasma from horses treated with aspirin or in charcoal treated TXB2-free plasma. Standard curves determined in plasma and buffer were parallel. This assay was used to determine the half-life of exogenous TXB2 in horses. The mean value of 20.7 minutes (n = 3) is similar to that determined in other species. Storage of plasma samples at -20 degrees C for four months was found to alter the TXB2 levels in an unpredictable manner. Mean recovery was 102.4 per cent (SD 44.1). Effect of variability in sample collection and handling was assessed, but no consistent source of artifactual generation of TXB2 was found.     

Influence of insulin and substrate concentration on protein synthetic rate in fetal tissues

The influence of fetal plasma substrate and insulin concentrations on the fractional synthesis rate or turnover of the mixed proteins in the organs of fetal lambs was calculated from measurements of the rate of uptake of L-14C lysine by the protein in the steady state in utero. The control values for protein synthesis rate in the fetal organs of Welsh mountain ewes, 130 to 140 days' pregnant, were similar to those previously observed in the fetuses of Border Leicester ewes: the mean turnover rates were 38, 72, 40 and 63 per cent per day for the brain, liver, cardiac muscle and the placenta respectively; that for skeletal muscles was 6.8 per cent per day; the corresponding half lives were 2.15, 1.27, 1.8 and 1.42 days respectively and 11.3 days for skeletal muscle. A fivefold increase in the plasma glucose levels had no influence on protein turnover rate over a six hour period. A fourfold increase in the concentration of some amino acids, following a mixed infusion, decreased turnover rate in brain, heart and liver. The half life was increased by 30 per cent, but a small reduction in half life was observed in skeletal muscle. Insulin caused a fall in intracellular lysine concentration in skeletal muscle and in plasma, which suggests that the hormone can reduce muscle protein catabolism in the fetal lamb in the last trimester of gestation. Enhancement of synthesis rate occurred in the presence of the amino acid infusions only; the half life of the proteins was reduced by a factor of three. Insulin also increased placental protein synthesis rate by 50 per cent but had no influence on the other tissues studied.     

Survey of the provision of prophylactic dental care for horses in Great Britain and Ireland between 1999 and 2002

A survey of 854 horse owners, trainers and equestrian managers in 10 regions of Great Britain and Ireland showed that 83 per cent provided their horses with routine prophylactic dental care at fixed intervals, including 49 per cent at intervals of 12 months and 30 per cent at intervals of six months; a further 10 per cent provided it only when they felt it was required and 7 per cent did not provide it at all. Overall, 44 per cent of the owners had their horse's wolf teeth (first premolar) extracted routinely; when prophylactic dentistry was provided, it was carried out solely by equine dental technicians (EDTS) for 53 per cent of owners, solely by veterinarians for 35 per cent, by both EDTS or veterinarians for 10 per cent of owners and by other than veterinarians or EDTS for 1 per cent. There was confusion among some horse owners concerning the qualifications of the EDTS, because no recognised British qualification was available until towards the end of this survey in 2001. Several reasons were cited by owners for choosing between veterinarians and EDTS including their perceived qualifications, personal recommendations, costs, the availability of a wide range of dental equipment and sedation, and the time and effort devoted to the procedures.     

Determination of free and total cyst(e)ine in plasma of dogs and cats

BACKGROUND: In human blood, the amino acid cysteine forms disulfide bonds with itself and with other sulfhydryl compounds in their free form and with sulfhydryls in protein. Protein-bound cysteine is lost when plasma proteins are removed before amino acid analysis. OBJECTIVE: The purpose of this study was to assess the time course and extent of cyst(e)ine (cysteine + half-cystine) loss in dog and cat plasma. METHODS: An equal volume of 6% sulfosalicylic acid was added to plasma aliquots at 0, 2, 4, 10, 16, 24, 36, 48, 60, and 72 hours after separation of blood cells. Tris-2-carboxyethyl-phosphine hydrochloride (TCEP - HCl), a reducing agent, was used to regenerate total plasma cyst(e)ine after 3 months of sample storage (-20 degrees C). RESULTS: Initial free cyst(e)ine concentrations (mean +/- SEM) were higher in canine plasma (77 +/- 4 micromol/L) than in feline plasma (37 +/- 3 micromol/L). Free plasma cyst(e)ine concentrations in dogs and cats decreased after first-order kinetics, with a half-life of 23 and 69 hours, respectively. Total plasma cysteine after TCEP - HCl treatment was similar for dogs (290 micromol/L) and cats (296 micromol/L), but the percentage of free cysteine was higher (P = .02) in dogs (27%) than in cats (13%). Over half of the cyst(e)ine, homocysteine, cysteinylglycine, and glutathione were bound in vivo to plasma proteins. CONCLUSION: These results emphasize the importance of removing plasma proteins within 1 hour after blood collection for reliable assay of free plasma cyst(e)ine.     

Arthroscopic removal of osteochondral fragments of the palmar/plantar aspect of the metacarpo/metatarsophalangeal joints

This paper presents the results of arthroscopic surgery in 42 Standardbred trotters and three Finnish horses. Forty-five horses were operated on. The age range was one to seven years; 73 per cent of the horses were three years old or younger. Horses showed a variety of clinical signs ranging from moderate to severe lameness at slow speeds, to obscure lameness manifesting only at high speeds. Synovial effusion of the fetlock joint was rare. In this series, 44 horses that had Type I fragments and one horse that had Type III fragments were operated on. Of the 45 horses operated on, 23 (51 per cent) returned to speed training in three months and 41 (91 per cent) returned to speed training in six months. Three of 45 (6 per cent) were lame three months after the surgery when the trainer attempted to start speed training. One of those was sound six months after the operation. The remaining two (4 per cent) stayed lame due to a lesion in the affected joint. Two of 45 (4 per cent) discontinued training for other reasons. The horse with Type III fragments returned to speed training in three months.     

Management of horses showing stereotypic behaviour, owner perception and the implications for welfare

A telephone survey was conducted of 100 racing stables, 100 riding schools and 100 competition establishments (8,427 horses in total) to determine what management practices were being applied to horses showing stereotypic behaviour, and to determine the underlying reasons for them by assessing the perceptions and opinions of the people working with the horses. The results indicated that horse owners are concerned about stereotypic behaviour, first, because it reduces the performance of the animal (31, 30 and 27 per cent of the owners of racing stables, riding schools and competition establishments respectively), secondly, because it has adverse clinical effects on the horse (52, 55 and 56 per cent), and thirdly, because it reduces the monetary value of the animal (45, 59 and 31 per cent). The belief that these behaviours are learnt or copied also affects the management of affected horses: they are not allowed on to the premises by 4, 32 and 17 per cent of owners of racing stables, riding schools and competition establishments, respectively; attempts are made to remove the causal factors of the stereotypy by 35, 43 and 36 per cent; the behaviours are physically prevented by 77, 67 and 79 per cent, and the affected horses are kept separate from other horses by 39, 30 and 48 per cent.     

Dystocia in the bitch: A retrospective study of 182 cases

In a retrospective study of 182 cases of canine dystocia, no relationship was found between either breed or age and occurrence of dystocia. However, medium-sized breeds (between 12.7 and 20.5 kg bodyweight) were slightly over represented. Of the bitches that had whelped previously, 42 per cent had experienced dystocia. The dystocia was of maternal origin in 75.3 per cent of the cases, mainly due to uterine inertia, while 24.7 per cent were of fetal origin, mainly resulting from malpresentations/malorientations. The most common reason for dystocia was primary, complete uterine inertia (48.9 per cent) and 40 per cent of the bitches with this problem had small litters of one or two pups. The most common treatment was calcium and, or, oxytocin injection followed by a caesarean section. Digital manipulation including forceps delivery and, or, medical treatment was successful in only 27.6 per cent of the cases. Of the bitches studied, 65.7 per cent had a caesarean section. Pup deaths occurred in 52.2 per cent of the litters. Among bitches that had been treated within one to four-and-a-half hours after the beginning of second stage labour, 5.8 per cent of the pups died, whereas the corresponding value for bitches that had been treated between five and 24 hours after the beginning of second stage labour was 13.7 per cent. The total frequency of pup deaths was 22.3 per cent. These findings show that early diagnosis and prompt treatment are crucial in reducing the pup death rate in cases of dystocia.     

Cardiovascular response to exercise and training in the horse

The quality of the overall response to exercise in the horse is very similar to that seen in man and laboratory animals; differences are mainly quantitative and persist when relative body weight is taken into account. The apparently greater flow capacity of the equine muscle bed during maximal whole-body exercise implicates the extent of central circulatory adaptations as the limiting factor in performance but implies a role for increase in arteriolar capacitance/muscle capillarity as an appropriate response to intense endurance training. The blood oxygen-carrying capacity of the horse is often quoted as the major component of the animal's superior aerobic work capacity, although the measured maximal a-vO2 for the horse is only 2 to 3 ml greater than that found in elite athletes. In fact, comparison of published performance data for man and the horse reveals that improved a-vO2 accounts for 23 per cent of the difference, and increased Qc accounts for the remaining 77 per cent of the superior oxygen consumption in the horse. The extent to which the horse can increase Qc and muscle blood flow appears to represent its major adaptations for maximal aerobic performance. It is frequently observed that there have been far greater improvements in human athletic performance than in that of the race-horse, and this difference is usually attributed to the application of scientific training methods to the athlete. It has also been suggested that the horse may have reached the limit of its adaptive ability. The horse has a maximal oxygen pulse of at least 0.6 ml per kg per beat compared with 0.35 for man, a 90 per cent whole body oxygen extraction, and an 80 to 90 per cent higher muscle blood flow, with an overall capability of increasing Vo2 max by 35 times. These represent levels that would appear to be difficult to improve upon. However, insufficient research has been performed to firmly state true maxima for the horse, and current research does not reveal to what extent the horse is capable of responding to even conventional training methods. The relative improvement that such research could reveal would provide some objective guidance to the extent to which further improvement could be anticipated. A consistent finding in the majority of studies reviewed is the tendency for results to show a lack of statistical significance, which is particularly frustrating for a researcher when the trends are consistent with the initial hypotheses. This tendency arises because of small group sizes and inherent variability in the test population.(ABSTRACT TRUNCATED AT 400 WORDS)     

Taste and its importance to the domestic chicken

A comparison is made between normal birds and birds deprived of oral taste by bilateral section of the lingual nerves. Following nerve section the birds showed a marked reduction of food intake for the first few days after operation. On presentation of a novel diet birds with sectioned nerves rejected it, the extent of rejection depending on the mode of presentation and on the degree of novelty. It is suggested that taste plays a major role in the initial selection of food and possibly in the motivation to eat. The birds preferred a diet with 2 per cent citric acid added and a rejected one with 5 per cent sodium chloride; these effects were probably oral in origin. There was rejection of a diet with 0.5 per cent quinine hydrochloride which was rapid in all birds, with or without nerve section. There was a preference in all birds for a diet with 20 per cent sucrose; this may be post‐ingestional in origin.     

A scheme for the separation and estimation of nitrogenous components of the excreta from poultry

An account is given of the development of a new scheme for assessing the relative proportions of nitrogenous end‐products of digestion and metabolism in excreta from laying hens. A series of solvent extractions with methanol‐chloroform‐water, phenol‐acetic acid‐water and lithium carbonate solution removed over 90 per cent of the nitrogen from excreta. In each extract estimations were made of the concentrations of certain nitrogenous components considered to be important such as urate, ammonia, urea, creatine, creatinine and amino acids.

Fractionation of nitrogen in a sample of excreta showed that over half the nitrogen appeared in the methanol‐water extract and about a third in the phenol‐acetic acid‐water extract. About 60 per cent of the extractable nitrogen was derived from urate, about 10 per cent from large non‐dialysable molecules, 9 per cent from ammonia, 2 per cent from free amino acids, possibly 3 per cent from peptides, 2 per cent from urea and 1 per cent from creatine and creatinine.     

Treatment of broiler litter with organic acids

Experiments for treatment of contaminated broiler litter with citric, tartaric and salicylic acids were performed. At days 2 and 6 after the treatment, pH values (using a pH-meter), the ammonia concentrations (titration with 0.1 N HCl) and the microbial cells counts were determined in both experimental and control specimens of litter. The cost of acidification of litter was also determined. Our studies showed that the treatment of the contaminated litter with 5 per cent citric acid, 4 per cent tartaric acid and 1.5 per cent salicylic acid created an acid medium with pH under 5.0 and thus reduced the microbial counts to 2.2 x 10(3)colony forming units per gram manure litter. The treatment reduced the content of ammonia in the litter and in the air under the hygienic limits, i.e. 25-50 ppm. The cost of acidification of litter with these organic acids amounted to 0.1 $ per bird and 1.5 $ per 15 birds on one square metre in a growth period of 50 days.