Influence of an n‐3 long‐chain polyunsaturated fatty acid‐enriched diet on experimentally induced synovitis in horses

Dietary n‐3 long‐chain polyunsaturated fatty acid (LCPUFA) supplementation has previously been shown to modify joint‐related inflammation in several species, although information in the horse is lacking. We investigated whether dietary supplementation with n‐3 LCPUFA would modify experimentally induced synovitis in horses. Twelve, skeletally mature, non‐pregnant mares were randomly assigned to either a control diet (CONT) or an n‐3 long‐chain fatty acid‐enriched treatment diet (N3FA) containing 40 g/day of n‐3 LCPUFA for 91 days. Blood samples taken on days 0, 30, 60 and 90, and synovial fluid collected on days 0 and 90 were processed for lipid composition. On day 91, joint inflammation was stimulated using an intra‐articular (IA) injection of 100 ng of recombinant equine IL‐1beta (reIL‐1β). Synovial fluid samples taken at post‐injection hours (PIH) 0, 4, 8 and 24 were analysed for prostaglandin E₂ (PGE₂), matrix metalloproteinase (MMP) activity and routine cytology. Synovium and articular cartilage samples collected at PIH 8 were analysed for gene expression of MMP 1 and MMP 13, interleukin‐1beta (IL‐1β), cyclooxygenase 2 (COX‐2), tumour necrosis factor‐alpha and the aggrecanases, a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS)‐4 and ADAMTS‐5. A 90‐day feeding period of n‐3 LCPUFA increased serum phospholipid and synovial fluid lipid compositions of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) compared to CONT horses. The reIL‐1β injection caused an inflammatory response; however, there was no effect of dietary treatment on synovial fluid PGE2 content and MMP activity. Synovial tissue collected from N3FA horses exhibited lower expression of ADAMTS‐4 compared to CONT horses. Despite the presence of EPA and DHA in the synovial fluid of N3FA horses, dietary n‐3 LCPUFA supplementation did not modify synovial fluid biomarkers compared to CONT horses; however, the lower ADAMTS‐4 mRNA expression in N3FA synovium warrants further investigation of n‐3 LCPUFA as a joint therapy.     

Effect of Ergovaline Ingestion on Recovery of Horses Subjected to an Anaerobic Standard Exercise Test

The objective of this study was to determine whether consumption of tall fescue seed which contained high levels of ergovaline would affect post-exercise recovery of horses subjected to an anaerobic exercise test. Ten Quarter horses were separated into two groups and fed alfalfa hay, commercial sweet feed, and either endophyte-infected (E+) or endophyte-free (E−) ground tall fescue seed. Diets contained 11.8% seed, which resulted in 459 ppb of ergovaline for the E+ diet. During the first 28 days, horses in group A received E+ and group B received E−. Diets were reversed during the next 28 days (crossover design). Horses were ridden for 5 days per week. On day 14, 28 (period 1), 42, and 56 (period 2), they were subjected to a standardized exercise test (SET) that consisted of 41 turns in 4 minutes and was designed to raise the horse’s heart rate (HR) beyond the anaerobic threshold (150 bpm). There was a horse effect (P < .05) on post-SET respiration rate, HR, and post-exercise whole blood lactate level, but not rectal temperature (RT). For these variables or period effects, there was no horse × treatment, period × treatment, or period × horse interactions (P < .05). Treatment had no effect on whole blood lactate level, RT, or HR at any time measured. Respiration rate did not vary by treatment at rest or 1 minute after SET but was higher for the E+ treatment at 5 and 10 minutes after SET (P < .005). Consumption of diets that averaged 450 ppb of ergovaline caused the horses expend more respiratory effort in an attempt to recover to resting RT.     

Comparison of various treatments for experimentally induced equine infectious arthritis

To evaluate the effects of 5 treatments on clinical responses, synovial fluid analysis, radiographic changes, bacteriologic culture results of the synovial fluid and synovial membrane, microscopic characteristics of the synovial membrane, and articular cartilage histochemistry, Staphylococcus aureus organisms (1.6 X 10(6) colony-forming units) were inoculated into the tarsocrural joints of 12 horses (n = 24 joints; 2 joints/horse). Each horse was given phenylbutazone (2 g) orally, every 24 hours, beginning 24 hours after inoculation. Two horses (ie, 4 joints) were not given other treatment (controls; group 1). All other horses (ie, 20 joints) were given a trimethoprim-sulfadiazine combination orally, once daily (30 mg/kg; 8 joints) or twice daily (30 mg/kg q 12 hr; 12 joints). Each of these 20 joints were assigned to 1 of 5 treatment groups (4 joints/group) in a balanced incomplete block design. Group 2 (4 joints) was given only the antibiotics once daily. Twelve joints were treated by through-and-through joint lavage on day 1 (group 3), days 1 and 3 (group 4), or days 1, 3, and 6 (group 5). Joints in group 6 had an arthrotomy performed on day 1, with subsequent lavage via an indwelling drain every 12 hours for 4 days. In groups 3 through 6, 1 joint in each group was treated with antibiotics once daily, and 3 joints were treated with antibiotics twice daily. All horses were clinically assessed each day. Complete blood count was performed on days 3, 6, 10, and 21. Before inoculation and on days 0, 1, 3, 6, 10, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, WBC count, differential count, and mucin clot-forming ability. Synovial fluid specimens were cultured bacteriologically before inoculation and on days 0 and 21. Horses in group 1 (controls) were euthanatized before day 6. All other horses were euthanatized on day 21. Tarsocrural joints were opened and examined. Synovial membrane specimens were bacteriologically cultured. Synovial membrane specimens were examined histologically (hemotoxylin and eosin stain) and articular cartilage specimens were (safranin O fast green stain) evaluated histochemically. Synovial membrane specimens were histologically graded into 5 categories. Intensity of articular cartilage intercellular staining with safranin 0 was graded for superficial, outer intermediate, inner intermediate, and deep zones. Two-way analysis of variance was performed to evaluate differences among groups and across time for the determinants evaluated.(ABSTRACT TRUNCATED AT 400 WORDS)     

Erythrogram and red cell distribution width of Equidae with experimentally induced anemia

The erythrogram (erythrocyte histogram) and red cell distribution width (RDW) were evaluated in 5 purebred horses and 1 pony of mixed breeding with experimentally induced anemia. Four horses were studied for 6 weeks after 20% of their estimated blood volume was removed on each of 2 consecutive days (40% total blood loss; acute blood-loss group). Two horses were given acetylphenyl hydrazine IV daily, until acute Heinz body hemolytic anemia was induced; the 2 horses were then evaluated for 6 weeks. One horse and the pony had 20% of their estimated blood volume removed via phlebotomy once each week for 8 weeks to induce iron-deficiency anemia (chronic blood-loss group); the horse had been partially depleted of iron before the study began. Weekly blood samples were examined for changes in the erythrogram, RDW, mean cell volume (MCV), and erythrocyte glucose-6-phosphate dehydrogenase activity. Fourteen days after acute blood loss, mild increases were seen in the MCV, which persisted to day 42. The RDW was increased at day 14 and remained increased until day 42; however, the percentage increase was double that of the MCV at days 14, 21, and 28. Erythrograms had mild extensions of the right slope at days 14 to 28. Mean erythrocyte glucose-6-phosphate dehydrogenase activity increased in all 3 groups, but individual concentrations were erratic. In the 2 horses with acute hemolytic anemia, modest increases of similar magnitude were seen in RDW and MCV.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of dose and diet on the pharmacokinetics of omeprazole in the horse

This study aimed to investigate the effect of diet and dose on the pharmacokinetics of omeprazole in the horse. Six horses received two doses (1 and 4 mg/kg) of omeprazole orally once daily for 5 days. Each dose was evaluated during feeding either a high‐grain/low‐fibre (HG/LF) diet or an ad libitum hay (HAY) diet in a four‐way crossover design. Plasma samples were collected for pharmacokinetic analysis on days 1 and 5. Plasma omeprazole concentrations were determined by ultra‐high pressure liquid chromatography–mass spectrometry. In horses being fed the HG/LF diet, on day 1, the area under the curve (AUC) and maximal plasma concentration (C_max) were higher on the 4 mg/kg dose than on the 1 mg/kg dose. The AUC was higher on day 5 compared to day 1 with the 4 mg/kg dose on the HG/LF diet. On days 1 and 5, the AUC and C_max were higher in horses being fed the HG/LF diet and receiving the 4 mg/kg dose than in horses being fed the HAY diet and receiving the 1 mg/kg dose. These findings suggest that both dose and diet may affect pharmacokinetic variables of omeprazole in the horse.     

Effects of feed form on growth and blood glucose in weanling horses

Eight weanling Standardbred horses were used to evaluate the effects on growth and plasma glucose of two differently processed diets with identical ingredients fed at a rate of 3% of body weight, as fed, daily. The daily ration was divided into two equal feedings at 7:00 am and 7:00 pm. The hay and grain diet (diet HG) consisted of 50% alfalfa hay cubes and 50% of a commercial growing horse texturized grain mix fed as is, without any further processing, with each part fed in separate containers. The completely pelleted diet (diet P) consisted of the same proportions of the hay cubes and grain mix that was ground, pelleted, and fed in a single container. Two groups of four horses were fed either diet P or diet HG for two 21-day periods such that each horse consumed each diet for 21 days. On the last day of each feeding period, 7-mL blood samples were drawn into heparinized evacuated blood tubes for determination of plasma glucose concentration. Blood samples were drawn 30 minutes before the afternoon feeding, immediately before, and every 30 minutes thereafter for 5 hours. Analysis of variance found greater (P = .027) average daily gain for horses fed diet P versus diet HG. A nonsignificant difference was seen in feed efficiency (P = .057) for horses fed diet P versus diet HG. Plasma glucose changes were compared across treatments using area under the curve analysis. No difference (P > .05) was found in the postprandial plasma glucose changes between diet treatments.     

Effects of continuous intra-articular infusion of gentamicin on synovial membrane and articular cartilage in the tarsocrural joint of horses

OBJECTIVE: To determine the effects of a continuous intra-articular infusion of gentamicin on the synovial membrane and articular cartilage in the tarsocrural joint of horses. ANIMALS: 6 healthy adult horses. PROCEDURE: A balloon infusion system attached to a catheter placed in the plantarolateral pouch of both tarsocrural joints in each horse was used for continuous gentamicin solution (GM) or balanced electrolyte solution (BES) delivery for 5 days. Cartilage and synovial membrane specimens were collected on day 5 from 3 horses and on day 14 from the remaining 3 horses. Both infused joints from each horse were assessed, using gross evaluation and histologic scoring systems. RESULTS: Significant differences in the histologic scores of synovial membrane specimens between the GM- and BES-treated joints at either 5 or 14 days were not observed. Safranin-O-fast green staining scores were similar between cartilage specimens from GM- and BES-treated joints. Although the synovial membrane histologic scores and safranin-O-fast green staining scores improved from day 5 to 14, the changes in scores were not significant. Loss of synovial intimal cells from villi was found more commonly in sections of synovial membrane from GM-treated joints, compared with BES-treated joints. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous infusion of GM into the tarsocrural joint of horses does not have significant effects on histologic scores of articular cartilage or synovial membrane, compared with those infused with BES. Continuous infusion of GM into the tarsocrural joint of horses for 5 days is an acceptable method for the treatment of septic arthritis.     

Povidone-iodine lavage treatment of experimentally induced equine infectious arthritis

Both tarsocrural joints of 4 horses were inoculated with 1.5 X 10(5) colony-forming units of Staphylococcus aureus. On days 1, 3, and 6, each horse had one tarsocrural joint lavaged with a balanced electrolyte solution and had the contralateral tarsocrural joint lavaged with 0.1% povidone-iodine solution. All horses were orally administered trimethoprim (5 mg/kg)/sufadiazine (25 mg/kg) combination twice daily and phenylbutazone (2 g) once daily for the duration of the study (21 days). On days 0, 1, 3, 6, 9, 14, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, WBC count and differential, and mucin clot-forming ability. Synovial fluid specimens collected on days 1, 3, 6, 9, 14, and 21 were bacteriologically cultured. On day 21, all horses were euthanatized, the tarsocrural joints were opened and examined, synovial membrane specimens were collected, bacteriologically cultured, and histologically evaluated, and articular cartilage specimens were histochemically evaluated. Repeated measures analysis of variance were used to evaluate differences between lavage solutions and among days for objective measurements. A paired t test was used to evaluate differences between solutions for the indices of synovial membrane inflammation and articular cartilage staining intensity with safranin-O-fast green. To be considered significant, the probability of a type-I error was less than 0.05. Significant differences were not found between joints lavaged with electrolyte solution vs povidone-iodine solution for synovial total protein concentration, WBC count, results of synovial fluid and membrane bacteriologic culture, synovial membrane inflammation, or articular cartilage glycosaminoglycan concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

An Intensive Approach in the Treatment of Clinical Equine Protozoal Myeloencephalitis

Equine protozoal myeloencephalitis (EPM) is a serious parasitic disease of horses producing neurologic clinical signs. Sarcocystis neurona is an incriminated pathogen. If approximately 50% of US horses are seropositive but only 0.5 to 1% become clinically affected, there is a suspected immunologic influence whether a horse is S. neurona-exposed or has clinical EPM syndrome. This report presents a treatment of 28 performance horses that were serum immunoblot positive for exposure to S. neurona. This patient population was in full athletic competition, travel, or training with associated stress. We attempted to (1) improve the immunologic status of the horse, (2) protect it against inflammatory reactions, and (3) provide medication to kill the protozoa. The cell-mediated immunity was stimulated by transfer factor in the feed for 37 days. The inflammatory reactions of treatment crises from antiprotozoal activity were prevented by MicroLactin (a neutrophil-activation inhibitor) in feed for 28 days concurrently. The antiprotozoal drug ponazuril was given concurrently for 28 days. Gait abnormalities, stumbling, and behavior change were the most frequent and combined clinical signs before treatment. There were 82% (23/28) treatable horses that were back at work, including five horses that were in physical rehabilitation under saddle. Five severely affected horses were not helped by therapy.     

Effect of ‘tongue tie’ use on racing performance of Thoroughbreds in the United Kingdom

Reasons for performing study: There is contradictory published evidence on the potential efficacy of ‘tongue ties’ (TTs) for treatment of intermittent dorsal displacement of the soft palate (DDSP) in racehorses. Objectives: To evaluate the effect of TTs on racing performance in Thoroughbred racehorses in the UK using a retrospective cohort study. Methods: Data on individual horses' lifetime racing performance and TT use were retrieved from the Racing Post Online Database. Exposed cases were horses that ran with a TT in randomly chosen race meetings on one of 60 randomly chosen dates from 2001–2003. Unexposed (control) horses were matched to each exposed horse. Various measures of racing performance were analysed both within and between exposed and unexposed groups. Subsets of exposed horses that ran for 3 or 5 consecutive starts wearing TTs and their matched controls were analysed separately to examine the effect of repeated TT use. Results: The inclusion criteria were fulfilled by 108 horses. The odds ratio for ‘improvement’ in race earnings between exposed and unexposed horses was 1.85 for horses that ran at least once with a TT, and 3.60 and 4.24, respectively, for horses that ran in 3 or 5 consecutive races wearing a TT. After instigation of TT use, horses that ran in 3 or 5 consecutive races wearing a TT had a significant increase in earnings when they ran wearing a TT compared to their pre‐TT races. Conclusions and potential relevance: The use of a TT appears to have a beneficial effect on racing performance in a selected population of Thoroughbred racehorses.     

Circadian rhythm of calciotropic hormones,serum calcium,phosphorus and magnesium during the shortest and longest days of the year in horses in New Zealand

A study was conducted to determine the circadian rhythms and trends of vitamin D metabolites including 25‐hydroxyvitamin D₃, 25‐hydroxyvitamin D₂, 1,25‐dihydroxyvitamin D and parathyroid hormone, in addition to serum calcium, phosphorus and magnesium concentrations in horses over 48 h on the shortest and longest days of the year in 2013. Five healthy adult horses (Equus caballus) were on a constant pasture feeding regimen, and blood samples were collected from each horse every 3 h over a 48‐h period, starting at 07:00 PM on day one and finishing at 07:00 PM on day three, for the measurement of calciotropic hormones and electrolytes. There was a significant difference between the serum concentration of calciotropic hormones, iCa, tCa, P and tMg between the shortest (winter) and longest (summer) days of the year in horses. Serum concentration of 25OHD₃ was very low and mostly undetectable. Serum iCa, 1,25(OH)₂D and PTH concentrations clearly showed a circadian rhythm on the longest days of the year and serum tCa, P and tMg concentrations showed a diurnal pattern on the longest days (summer) of the year. None of the analytes showed any circadian rhythm on the shortest days (winter) of the year. The result of this study could have significant relevance to equine athletes travelling to international equestrian competitions and facing a huge time and seasonal differences that might affect their ability to adjust their circadian rhythms to new time zones.     

The pharmacokinetics and antiparasitic activity of ivermectin in Hutsul and Toric horses

The aim of this study was to compare the pharmacokinetics of ivermectin and its antiparasitic activity in two horse breeds. Eight Hutsul and 14 Toric horses were administered ivermectin orally at a dose of 0.2 mg/kg body weight. Blood samples were collected for 96 hr, and faecal samples were collected one day before and on days 14 and 21 after drug administration. Ivermectin concentrations in plasma samples were determined by high‐performance liquid chromatography. Ivermectin concentration was significantly higher in Toric than in Hutsul horses 90 min after ivermectin administration and was maintained at higher level for up to 96 hr. The area under the concentration versus the time curve from 0 to the last sampling point (AUC_0→t) and the maximum plasma concentration (C_max) were significantly higher in Toric than in Hutsul horses (1792.09 ± 246.22 μg × hr/L vs. 716.99 ± 255.81 μg × hr/L and 62.72 ± 17.97 ng/ml vs. 35.34 ± 13.61 ng/ml, respectively). No parasitic eggs were found in the faecal samples collected from both groups of horses on days 14 and 21 after drug administration. The obtained results indicate that although the pharmacokinetics of ivermectin may differ significantly between horse breeds, these differences do not affect the effectiveness of therapy.     

Physiological Response of Normal Adult Horses to a Low-Residue Liquid Diet

The anorexic or dysphagic adult horse often requires nutritional support. Providing nutrients by the enteral route is the safest and most economic choice, but the dietary options available for use in horses are somewhat limited. The objective of this study was to compare the physiologic response of normal horses with a low-residue liquid or normal diet over a 10-day feeding period. Two groups of 6 normal adult horses were maintained on 1 of 2 diets for a 10-day period. Diets were formulated to meet the caloric needs of a horse maintained in a stall. The control group was fed 70% timothy hay and 30% textured concentrate for the test period, and the experimental group received the low-residue liquid diet, similar to liquid nutritional formulas designed for human use. Clinical parameters, body weight, packed cell volume, total plasma solids, blood glucose, and serum electrolytes were recorded daily for each horse during the dietary trial period. On days 1, 5, and 10 of the study, a complete blood count, serum biochemical profile, and urinalysis were performed.Horses' serum total bilirubin concentration and pattern of weight loss differed between groups. All other physical parameters, blood chemistry, complete blood count, and urinalysis results remained within the normal reference interval for the horses regardless of diet, although some statistical differences were observed. Horses returned to pasture and free-choice grass diet without complications at the end of the dietary trial period. These results demonstrate that few differences of biologic significance were observed between horses being fed low-residue diet and horses receiving a normal diet of hay and grain over a 10-day period. (Equine Vet J 2003;23:310–317)     

Oral rosmarinic acid-enhanced Mentha spicata modulates synovial fluid biomarkers of inflammation in horses challenged with intra-articular LPS

A biological extract of high-rosmarinic acid mint (HRAM) has previously demonstrated inhibitory effects on lipopolysaccharide (LPS)-induced prostaglandin E(2) (PGE(2)), nitric oxide (NO) and glycosaminoglycan (GAG) release in vitro. This study was undertaken to determine whether HRAM added to feed produces similar effects in horses challenged with intra-articular LPS. Eight horses received HRAM (0 or 28.1 ± 1.3 g/day; n = 4 per group) in their feed for 24 days in a blinded manner. On day 21, all horses received an intra-articular injection of LPS (0.3 ng) into their left or right intercarpal joint. Synovial fluid (SF) samples were taken on postinjection day (PID)-21 (i.e. prior to commencement of supplementation), PID0, PID0.25, PID0.5, PID1 and PID3 and analysed for PGE(2), GAG, NO, protein and total nucleated cells counts. Blood biochemistry and haematology screens were conducted at PID-21, PID0, PID1 and PID3. There was a significant reduction in LPS-induced PGE(2) and GAG in SF in horses supplemented with HRAM compared with controls and a tendency to increase complement recognition protein accumulation in synovial fluid of HRAM horses. Plasma from HRAM horses had reduced total white blood cells, segmented neutrophils (compared with baseline concentrations) and lymphocytes (compared with controls), and increased SF nucleated cell count (compared with baseline concentrations and controls). It is concluded that HRAM offered as part of the feed alter biomarkers of inflammation in SF of LPS-challenged horses. Larger studies that seek to clarify effects of HRAM on synovial fluid cell counts and possible role of HRAM-induced interference with complement signalling are warranted.     

Rectal temperature as an indicator for heat tolerance in chickens

High environmental temperature is perhaps the most important inhibiting factor to poultry production in hot regions. The objective of this study was to test adaptive responses of chickens to high ambient temperatures and identify suitable indicators for selection of heat‐tolerant individuals. Full‐sib or half‐sib Anak‐40 pullets (n = 55) with similar body weights were raised in a room with a temperature ranging from 24°C to 28°C, and relative humidity of 50% from 61 to 65 days of age. On day 66, the ambient temperature was increased within 60 min to 35 ± 1°C which was defined as the initial of heat stress (0 h). Rectal temperature (RT) was measured on each pullet at 0, 6, 18, 30, 42, 54 and 66 h. After 66 h the ambient temperature was increased within 30 min to 41 ± 1°C and survival time (HSST) as well as lethal rectal temperatures (LRT) were recorded for each individual. The gap between the RT and initial RT was calculated as ΔTn (ΔT6, ΔT18, ΔT30, ΔT42, ΔT54 and ΔT66), and the interval between LRT and initial RT as ΔTT, respectively. A negative correlation was found between HSST and ΔTn as well as ΔTT (r_ΔT18 = ?0.28 and r_ΔTT = ?0.31, respectively, P < 0.05; r_ΔT30 = ?0.36, r_ΔT42 = ?0.38, r_ΔT54 = ?0.56, P < 0.01). Importantly, pullets with low ΔT18 showed a longer HSST (256.0 ± 208.4 min) than those with high ΔT18 (HSST = 123.7 ± 78.3 min). This observation suggested that the ΔT18 or early increment of RT under heat stress might be considered as a reliable indicator for evaluation of heat resistance in chickens.     

Hypoxaemia during anaesthesia in seven horses with colic

Anaesthetic records of horses with colic anaesthetised between June 1987 and May 1989 were reviewed. pH and blood gas analyses were performed during 157 operations from which the horses were allowed to recover. A PaO₂ of 8.0 kPa or less was measured during anaesthesia in seven of these horses. The horses were of different breeds, ages and sexes. Anaesthesia was induced with xylazine, guaifenesin and ketamine in four horses and with xylazine, guaifenesin and thiobarbiturate in three horses. Anaesthesia was maintained with inhalation anaesthetic agent and oxygen: isoflurane in five horses, halothane in one horse, and initially halothane but later isoflurane in one horse. Systolic arterial pressures during anaesthesia ranged from 80 to 150 mmHg, diastolic arterial pressures were between 60 and 128 mmHg, and heart rates were between 28 and 44 beats /min. Controlled ventilation was initiated at the start of anaesthesia. PaCO₂ exceeded 6.7 kPa in three horses but was subsequently decreased by adjustment of the ventilator. PaO₂ of 8.0 kPa or less was measured during early anaesthesia, with one exception, and persisted for the duration of anaesthesia. The horses' inspired air was supplemented with oxygen during recovery from anaesthesia, at which time measurement of blood gases in three horses revealed no increase in PaO₂. Recovery from anaesthesia was uneventful. The surgical problems involved primarily the large intestine in five horses and the small intestine in two horses. Six horses were discharged from the hospital alive; one horse was reanaesthetised later the same day and destroyed without regaining consciousness. We concluded that none of the objective values recorded during the pre-anaesthetic evaluation could have been used to predict the complication of intraoperative hypoxaemia. We observed that once hypoxaemia developed it persisted for the duration of anaesthesia and even into the recovery period when the horses were in lateral recumbency and regaining consciousness. We assume that the altered metabolism from anaesthetic agents and hypothermia combined with adequate peripheral perfusion contributed to the lack of adverse consequences in six of the horses. The contribution of hypoxaemia to the deteriorating condition of the seventh horse is speculative.     

Studies on Blood and Serum Types of the Icelandic Horses

By means of isoimmunizations and heteroimmunizations 10 equine blood typing reagents were isolated. The specific antibodies were complete agglutinins, which were used in the direct agglutination test in saline medium. The reagents were designated A₂, C, D, E, G, H, I, K, Da₁, and Da₂ reagent. Da₁ and Da₂ are preliminary designations.The data obtained from blood typing of a family material and a population material of Icelandic horses showed that the occurrence of each blood type factor is controlled by a single, dominant gene. The family data tended to show that the blood factors under investigation belonged to 8 blood type systems. The A system contained the antigens A₂ and Da₂. These antigens are related to each other through a linear subgroup relationship. The D system had the factors D and J. The G, E, G, I, K, and Da₁ systems are one-factor, two-allele blood type systems. The H factor was not observed in Icelandic horses. In connection with the establishment of the 8 blood type systems it must be emphasized that the problem of allelism or nonallelism of 2 genes can only be solved by means of relevant family data. Because of the rare occurrence of some of the blood factors in the Icelandic horse such data were in some cases not available. Thus some conclusions were based on results from two-by-two contingency tables with the use of population data. This was used particularly for the D and G systems, and additional family data are necessary for a definite establishment of these systems.Exceptions to the genetic theory, apparently caused by erroneous registration, were presented.Finally, estimates were given of gene frequencies of the causative genes among Icelandic horses.Starch gel electrophoresis of sera from Icelandic horses revealed the existence of 21 transferrin phenotypes. The data obtained supported the theory advanced, that transferrin polymorphism in horses is controlled by 6 autosomal codominant alleles: Tf^D, Tf^F, Tf^H, Tf^M, Tf^O, and Tf^H.925 randomly selected Icelandic horses were typed for serum transferrin and the gene frequencies were estimated.Starch gel electrophoresis of about 100 horse serum samples did hot reveal individual variation of the equine haptoglobin and ceruloplasmin. Studies on approximately 300 sera showed an identical serum amylase pattern.     

Hematogenous (suspected-)septic inflammation of the synovial fossa in the adult horse: rare but deceptive (3 case reports)

Septic inflammation of the synovial fossa in the horse is a severe disorder that can lead to permanent invalidity. The synovitis can occur as a result of a perforating trauma, or via the blood (haematogenous). The latter route is rare in the adult horse. Three cases of suspected haematogenous septic synovitis are described in adult horses (older than 1 year). In two horses, timely and adequate treatment resulted in recovery, but this was followed by fatal recurrence. In one of these horses a persistent primary infection was found as cause; the other horse was not available for autopsy. The third horse was euthanized without treatment because the primary process was difficult to treat. It can be concluded that, in horses with suspected haematogenous septic inflammation of the synovial fossa, attention should be paid to the primary process--it is not enough to treat the synovitis alone.     

Low-dose ginseng (Panax quinquefolium) modulates the course and magnitude of the antibody response to vaccination against Equid herpesvirus 1 in horses

The purpose of this study was to determine if ginseng fed at low levels enhances a horse's antibody response to vaccination against Equid herpesvirus 1 (EHV-1). For 28 d, 5 horses received ground, powdered ginseng (35 mg/kg body weight, 1.7 mg/kg total ginsenosides) in molasses as a carrier, and 5 received molasses only. On day 14, each horse was vaccinated against EHV-1. The time course of the antibody response to vaccination was significantly altered in the horses receiving ginseng, a clinically relevant increase in antibody titer being observed by postvaccination day 2 compared with day 6 in the control horses. The horses receiving ginseng also had a significant decrease in serum levels of sodium and a significant increase in serum levels of potassium. No adverse effects of ginseng treatment were identified by hematologic and blood biochemistry profiles. Thus, low-dose dietary supplementation with ginseng in healthy horses may be a useful adjunct to vaccination.     

Responses to an intra-articular lipopolysaccharide challenge following dietary supplementation of Saccharomyces cerevisiae fermentation product in young horses

Dietary intervention may be a valuable strategy to optimize the intra-articular environment in young horses to prolong their performance career. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would reduce markers of joint inflammation and increase markers of cartilage metabolism following a single inflammatory insult, Quarter Horse yearlings (mean ± SD; 9 ± 1.0 mo) were balanced by age, sex, body weight (BW), and farm of origin and randomly assigned to the following treatment groups: 1.25% BW/d (dry matter basis) custom-formulated concentrate only (CON; n = 9) or concentrate top-dressed with 21 g/d S. cerevisiae fermentation product (SCFP; n = 10) for 98 d. Horses had ad libitum access to Coastal bermudagrass hay. On day 84, one randomly selected radial carpal joint from each horse was injected with 0.5 ng lipopolysaccharide (LPS) solution. The remaining carpal joint was injected with sterile lactated Ringer’s solution as a contralateral control. Synovial fluid obtained before supplementation (day 0) and on day 84 at preinjection hour 0 and 6, 12, 24, 168, and 336 h postinjection was analyzed for prostaglandin E₂ (PGE₂), carboxypropeptide of type II collagen (CPII), and collagenase cleavage neopeptide (C2C) by commercial assays. Rectal temperature, heart rate, respiration rate, carpal surface temperature, and carpal circumference were recorded prior to each sample collection and for 24 h postinjection. Data were analyzed using linear models with repeated measures. From day 0 to 84, synovial C2C declined (P ≤ 0.01) and the CPII:C2C ratio increased (P ≤ 0.01) in all horses with no effect of diet. In response to intra-articular LPS, synovial PGE₂ increased by hour 6 (P ≤ 0.01) and returned to baseline by hour 336; CPII increased by hour 12, remained elevated through hour 168 (P ≤ 0.01), and returned to baseline by hour 336; and C2C increased by hour 6 (P ≤ 0.01) but did not return to baseline through hour 336 (P ≤ 0.01). Post-intra-articular injection, PGE₂ levels were lower in SCFP than CON horses (P = 0.01) regardless of injection type. Synovial CPII and the CPII:C2C ratio demonstrated stability during the LPS challenge in SCFP compared with CON horses (P ≤ 0.01). Clinical parameters were not influenced by diet but increased in response to repeated arthrocentesis (P ≤ 0.01). Dietary SCFP may favorably modulate intra-articular inflammation following an acute stressor and influence cartilage turnover in young horses.