Economic importance of protecting draft horses used in forestry against blood-sucking dipterous insects

The adverse effect of blood-sucking dipterous insects (gadflies, gnats, black flies, midges) was determined and checked, as exerted on the working performance of draft horses working in forests; the possibilities of protecting horses with repellents were studied at the same time. The trial was conducted under field conditions in the territory of the Broumov Forest Establishment in the Náchod and Trutnov districts. A 10% water emulsion of the repellent, diethyltoluamide, was used; the horses were treated with the emulsion in a 24-hour interval. Over the seventy working days from the 1st of July to the 30th of September, 1981, the performance of the test horse increased by 153 m3 wood in the skidding operation (i. e. by 58.06%), as compared with the control group. Recalculated per horse/day, this improvement is 2.19 m3 wood and the saving of prime costs amounts to 35.50 Czechoslovak crowns. The coefficient of loss per untreated horse was 9180 crowns. The effectiveness of the costs (per each crown of the capital expended) was calculated to be 309.07 crowns. The results were statistically significant.     

补喂芒柄花素对伊犁马1000m速度赛成绩、血气及抗氧化指标的影响

【目的】 研究芒柄花素对伊犁马1 000 m速度赛成绩、血气及抗氧化指标的影响，为伊犁马运动训练过程中营养补喂剂的研发提供参考依据。【方法】 试验选择平均体重(411 kg±29 kg)、平均年龄(2.0岁±0.50岁)、1 000 m速度赛成绩(135.24 s±15.75 s)相近并且健康状况良好的12匹伊犁马公马作为研究对象，随机分为对照组与试验组，每组6匹。在相同的饲养管理、饲粮营养水平及运动训练条件下，试验组每匹马每天补喂芒柄花素8 g，进行为期30 d的补喂试验。在试验第30天进行1 000 m速度赛，记录比赛成绩并在赛后即刻通过颈静脉采集血样，使用血气分析仪测定电解质水平、酸碱平衡及血气指标，使用试剂盒测定抗氧化指标。【结果】 补喂芒柄花素能够显著缩短伊犁马1 000 m速度赛比赛用时(P<0.05);对血浆中电解质水平、酸碱平衡及血气相关指标均无显著影响(P>0.05);在血浆抗氧化指标方面，补喂芒柄花素能够显著提高赛后马匹血浆中超氧化物歧化酶、过氧化氢酶和总抗氧化能力，分别比对照组提高了11.12%(P<0.05)、8.45%(P<0.05)和32.70%(P<0.05);而试验组谷胱甘肽过氧化物酶和丙二醛的含量分别比对照组降低1.56%和11.32%，但无显著差异(P>0.05)。【结论】 在本试验条件下，给伊犁马补喂芒柄花素能够显著提高1 000 m速度赛成绩，并提高其运动抗氧化能力。     

Determination of the activity of pyrantel tartrate against Sarcocystis neurona in gamma-interferon gene knockout mice

Equine protozoal myeloencephalitis (EPM) is the most important protozoal disease of horses in the United States. Some horse owners and equine clinicians believe that horses which are on daily pyrantel tartrate at 2.64mg/kg for helminth prophylaxis are less likely to develop EPM. The present study examined the efficacy of pyrantel tartrate in preventing clinical disease in gamma-interferon gene knockout (BALB/c-Ifng(tm1ts)) mice. No activity was seen against sporocyst-induced Sarcocystis neurona infections in mice treated prophylacticly with 4-5mg pyrantel tartrate per mouse per day in the drinking water.     

Expulsion of small strongyle nematodes (cyathostomin spp) following deworming of horses on a stud farm in Sweden

This study was conducted on a stud farm in Sweden to investigate the species composition of cyathostomins expelled in the faeces of horses after deworming using three different anthelmintic preparations. Twenty-seven horses excreting > or = 200 strongyle eggs per gram faeces (EPG) were divided into three comparable groups and dewormed on day 0 with either of following compounds: 0.2 mg ivermectin per kg body weight (bw), 19 mg pyrantel pamoate per kg bw or 7.5 mg fenbendazole per kg bw. For each of the 3 days following anthelmintic treatment faeces was collected from individual horses and subsamples were fixed in formalin. Four days after the anthelmintic treatment all horses were re-treated with ivermectin and faeces was collected on day 5. Individual subsamples from each of the four sampling occasions were examined for cyathostomin nematodes. Sixty-three to 270 worms per horse were identified to the species level. The majority of the worms recovered were expelled during the first day from horses treated with ivermectin or pyrantel pamoate, and during the second day from horses treated with fenbendazole. Fifteen cyathostomin species were identified and the six most prevalent were Cylicocyclus nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, Cylicocyclus leptostomus, Cylicostephanus minutus and Cylicostephanus calicatus. These species composed 91% of the total burden of cyathostomins. The number of species found per horse ranged from 6 to 13, with an average of 9. No significant differences in species composition or distribution were found between the treatment groups. On day 5, i.e. 1 day after the last ivermectin treatment, 93% of the adult worms were recovered from horses in the fenbendazole group.This study showed that it was possible to identify cyathostomins expelled in faeces of dewormed horses, and that the most prevalent species corresponded to those found in autopsy surveys performed in other countries.     

The effect of the sedative and analgesic detomidine for laryngoscopy of adult horses and foals]

Detomidine was used in this field trial effectively as a sedative and analgesic for laryngoscopic examinations in a total of 193 foals and 806 mature horses (Hanoverians). Detomidine was given either i.v. in foals 3 to 11 months old (20 micrograms/kg) and in mature horses (15 micrograms/kg), or i.m. in foals below 6 months of age (35 micrograms/kg). After i.v. administration, laryngoscopy was tolerated in more than 90% of all animals without additional use of a twitch, while in foals treated i.m. more than 70% required a twitch in order to enable this procedure. The effectiveness of detomidine was influenced by dose, route of administration, the time interval between treatment and examination and the degree of excitement before treatment, but not by sex. Profound bradycardia was evident in all treated animals, but arrhythmias were seen only in animals older than 4 months and were more pronounced in horses with a lower resting heart rate. These cardiovascular responses never endangered any of the treated animals. A transient dyspnea was seen in 13 foals (6.7%) and 10 horses (1.2%). Other side effects were rare. The foaling rate of 297 mares treated at any time during the first 8 months of pregnancy was 66.7%. A comparison with 5499 untreated, contemporary controls revealed a foaling rate of 61.0%. Hence treatments had no adverse effects on pregnancies.     

Clinical trials of efficacy of praziquantel horse paste 9% against tapeworms and its safety in horses

The aim of this study with horses and a few ponies naturally infected with tapeworms was to confirm in clinical trials the efficacy and safety of a praziquantel horse paste 9%. The field trials were conducted in 1997 and 1998 in Canada, France, Germany and New Zealand. A secondary aim of the study in Canada was to determine if a 24h post-treatment fecal sample provides the best estimate of the prevalence of tapeworms in horses when using a fecal examination technique. Fecal samples were taken from each of 1062 animals at least three times pre-treatment (PRT). In Canada, fecal samples were examined using the Cornell-Wisconsin centrifugal flotation technique, and in France, Germany and New Zealand using a centrifugation/flotation technique. In each trial, the animals were randomized into two treatment groups: praziquantel horse paste 9% at 1mg/kg body weight (BW) and untreated. Fecal samples were taken from each animal nine times post-treatment and over a period of 5 weeks. In Canada, a fecal sample was taken also at 24h after treatment. Personnel examining the samples were "blinded" to treatment groups. On the day of treatment, each treated animal was examined for adverse reactions to the paste 10min after treatment and then hourly for 4h. Thereafter, each animal was examined once daily for 5 weeks. In Canada, Germany and New Zealand, the only tapeworm egg found was Anoplocephala perfoliata. In France, A. perfoliata was the most common species and a few animals had A. magna and Paranoplocephala mamillana. The prevalence of A. perfoliata among animals sampled in Canada, France, Germany and New Zealand was 51.8, 34.4, 13.1 and 26.2%, respectively. A total of 248 animals were treated with the praziquantel paste and all except one accepted it readily. There were 292 animals completing the study, 219 treated and 73 untreated. In Canada, Germany and New Zealand, the efficacy of the praziquantel horse paste 9% against A. perfoliata was 100%. In France, the efficacy against A. perfoliata, A. magna and P. mamillana was 90.9, 100 and 100%, respectively. The best estimate of prevalence for A. perfoliata in a herd was derived from fecal samples taken 24h after treatment. At 24h, 22 of 23 treated horses were positive, whereas on any day pre-treatment fewer horses were positive. Adverse reactions observed were mild to moderate colic and in only two treated horses.     

Treatment of natural infestations of the biting louse (Werneckiella equi) on horses using triflumuron, a benzoylurea derivative insect growth regulator

The horse biting louse (Werneckiella equi) is a common global equine ectoparasite. To our knowledge, benzoyl(phenyl)urea insecticides (triflumuron, diflubenzuron) commonly used as sheep lousicides, have not been evaluated for efficacy against W. equi. The aim of this study was to determine louse control efficacy, general wellness and dermal safety following triflumuron application as a backline pour-on to horses. Two efficacy trials using 25 adult naturally infested lousy horses, and a dermal safety trial using 10 adult louse-free horses were conducted over a 14-month period. Lousy animals were selected by assessment of their lice status prior to treatment. For the efficacy trial, the triflumuron product was applied at a dose of 2.5mg triflumuron per kg bodyweight (1 mL product per 10 kg bodyweight). For the safety study, triflumuron was applied at a 3x clinical dose of 7.5 mg triflumuron per kg bodyweight (3 mL product per 10 kg bodyweight). In our first efficacy trial, 100% lousicidal efficacy was achieved by day 44 post-treatment. In our second trial, no lice were identified on horses by day 71 post-treatment. In the safety trial, no adverse effects were seen. Results of this study demonstrate that the off-label, experimental pour-on application of triflumuron at 2.5 mg/kg bodyweight is convenient, highly effective and safe (at 3x the clinical dose) for the treatment of the horse biting louse, W. equi.     

Pedunculated lipomas as a cause of intestinal obstruction in horses: 17 cases (1983-1990).

The medical records of 17 horses that were evaluated and treated because of colic caused by pedunculated lipomas between 1983 and 1990 were reviewed. The mean age of the horses was 16.6 +/- 3.9 years (range, 10 to 26 years), which was significantly greater than that of the population of horses evaluated because of colic (control population) during the same period. There were significantly more geldings (76.5%), compared with the control population. Nasogastric reflux ranged from 1 to 16 L in 8 horses and was not obtained in 9 horses. Abdominal palpation per rectum revealed small intestinal distention in 13 horses, displaced large colon in 7 horses, and large colon impaction in 2 horses. Peritoneal fluid was abnormal in 11 of 12 horses from which it was obtained successfully. One horse was euthanatized after unsuccessful medical treatment. Surgery was performed in 16 horses. Lipomas were blindly resected in 5 horses or exteriorized and resected in 6 horses. The method used to resect the lipoma was not recorded in 5 horses. The ileum and/or jejunum was strangulated in 15 horses, the small colon was strangulated in 1 horse, and the jejunum was obstructed in 1 horse. The length of intestine resected ranged from 0.15 to 7.2 m. Fourteen horses survived surgery, of which 11 were discharged from the hospital (short-term survival rate of 78.6%). Excluding 2 horses lost to follow-up evaluation, 6 of 12 horses that survived surgery were alive 2 to 56 months following surgery (long-term survival rate of 50%), and 9 of 15 horses died or were euthanatized (fatality rate of 60%).     

Effect of Betamethasone and Exercise on Equine Carpal Joints With Osteochondral Fragments

Osteochondral fragments were created arthroscopically on the distal aspect of both radial carpal bones in 12 horses. On day 14 after surgery, one middle carpal joint of each horse was injected with 2.5 mL Betavet Soluspan (3.9 mg betamethasone sodium phosphate and 12 mg betamethasone acetate per milliliter) and the contralateral joint was injected with 2.5 mL saline as a control. Intra-articular treatments were repeated on day 35. On day 17, six horses began exercising 5 days per week on a high-speed treadmill. The other six horses were kept in box stalls throughout the study as nonexercised controls. On day 56, all horses were examined clinically and radiographically and then were euthanatized. Samples were obtained for histological, his-tochemical, and biochemical evaluation. Mild lameness was observed in five of the six exercised horses at day 56; four horses were lame in the control limb and one horse was lame in the treated limb. Of the five nonexercised horses evaluated for lameness, two were lame in the control limb, two were lame in the treated limb, and one was lame in both the control and the treated limb. No differences were noted on radiographs or palpation of steroid treated limbs versus control limbs. Firm reattachment of the osteochondral fragment to the radial carpal bone occurred in all but three joints. Gross cartilage damage was not different between steroid-treated joints and joints injected with saline. Histologically, there were no significant detrimental effects of betamethasone with or without exercise, but there was a tendency for more pathological change in treated joints. There was a trend toward decreased glycosaminoglycan staining in steroid treated joints of rested horses, whereas exercised horses had similar glycosaminoglycan staining in treated and control joints. No significant difference in the water content or uronic acid concentration was detected between treated and control joints. Intra-articular betamethasone administration in this carpal chip model was not associated with any significant detrimental effects in either rested or exercised horses.     

Treatment of Mycotic Rhinitis With Itraconazole in Three Horses

Itraconazole, a third-generation azole, was evaluated for treatment of resistant nasal mycotic infections in horses. Two horses with Aspergillus spp nasal granulomas and 1 horse with Conidiobolus coronatus nasal infection were treated with itraconazole (3 mg/kg PO bid). One of the horses with nasal aspergillosis was also treated by surgical resection of the nasal septum. The treatment time for the horses ranged from 3 to 4.5 months. No adverse effects were noted in any of the horses during the treatment period. Peak and trough serum itraconazole concentrations were < 0.5 μg/mL in all 3 horses. Itraconazole (3 mg/kg PO bid) appears to be effective in the treatment of nasal Aspergillus spp infections in horses because the fungal infection was eliminated in both horses. One horse still had excessive nasal sounds during exercise and was retired from training, whereas the other horse returned to normal. The nasal C. coronatus infection appeared resistant to itraconazole treatment in the affected horse because the granulomas were still present after 4.5 months of treatment.     

Treatment of Atrial Fibrillation in Horses: New Perspectives

Forty-one horses were treated for atrial fibrillation (AF) with 22 mg/kg quinidine sulfate via nasogastric tube every 2 hours until conversion to sinus rhythm, a cumulative dose of 88 to 132 mg/kg had been administered in 2-hour increments, or the horse had adverse or toxic effects from the drug. Treatment intervals were prolonged to every 6 hours if conversion had not occurred. Digoxin was administered before treatment if the horse had a fractional shortening ≤ 27% (3 horses), was prone to tachycardia (resting heart rate ≥ 60 beats/min) (1 horse), or had a previous history of sustained tachycardia of over 100 beats/min during prior conversion (3 horses). Digoxin was administered during day 1 of quinidine sulfate treatment if the horse developed a sustained tachycardia of over 100 beats/min during treatment (11 horses) or on day 2 if conversion had not occurred (7 horses). Plasma quinidine concentrations within 1 hour of conversion of AF to sinus rhythm ranged from 1.7 to 7.5 μg/mL (mean, 4.05± 1.6) and ranged from 1.7 to 4.7 μg/mL in 97% of horses. Most horses (92%) with plasma quinidine concentrations > 5 μg/mL exhibited an adverse or toxic effect of quinidine sulfate (clinical or electrocardiographic). There was no statistical association between plasma quinidine concentrations and sustained tachycardia (> 100 beats/min), diarrhea, or colic. Ataxia and upper respiratory tract stridor were significantly associated with plasma quinidine concentrations. In most instances (98%) conversion did not occur while toxic or adverse effects of quinidine sulfate were present or when plasma quinidine concentrations were > 5 μg/mL.     

Effects of dexamethasone,glucose infusion,adrenocorticotropin, and propylthiouracil on plasma leptin concentrations in horses

In experiment 1, nine light horse geldings (three 3 x 3 Latin squares) received dexamethasone (DEX; 125 microg/kg BW, i.m.), glucose (0.2 g/kg BW, i.v.), or nothing (control) once per day for 4 days. DEX increased (P < 0.001) glucose, insulin, and leptin concentrations and resulted in a delayed increase (P < 0.001) in IGF-I concentrations. In experiment 2, mares were similarly treated with DEX (n = 6) or vehicle (n = 6). DEX again increased (P < 0.01) glucose, insulin, and leptin concentrations; the delayed elevation in IGF-I concentrations occurred on day 10, 12, and 19, relative to the first day of treatment. In experiment 3, six light horse geldings received either 200 IU of adrenocorticotropin (ACTH) i.m. or vehicle twice daily for 4 days. ACTH increased (P < 0.001) cortisol concentrations. Further, ACTH resulted in increases (P < 0.01) glucose, insulin, and leptin concentrations. In experiment 4, plasma samples from four light horse stallions that were fed 6-n-propyl-2-thiouracil (PTU) at 6 mg/kg BW for 60 days to induce hypothyroidism were compared to samples from control stallions. On day 52, stallions receiving PTU had lower concentrations of thyroxine (P < 0.05) and triiodothyronine (P < 0.01) and higher (P < 0.01) concentrations of TSH. Leptin concentrations were higher (P < 0.01) in PTU-fed stallions from day 10 through 52. In conclusion, circulating concentrations of leptin in horses was increased by administering DEX. Treatment with ACTH increased cortisol and resulted in lesser increases in leptin, glucose, and insulin. In addition, PTU feeding results in lesser increases in leptin concentrations.     

Effect of sodium bicarbonate on racing Standardbreds

Twenty-two Standardbred horses in race training were used in a crossover experiment to determine the effect of oral sodium bicarbonate (NaHCO3) administration on performance and metabolic responses to a 1.6-km (1-mile) race. Horses were paired and one horse in each pair was treated with either NaHCO3 (300 mg/kg BW) or a placebo, 2.5 h before they raced against each other. Each horse was scheduled to compete in two races, approximately 1 wk apart, one on each treatment. Horses always raced in the same pairs. Fourteen horses successfully completed both races. Jugular blood samples were obtained 1.5 h after treatment (rest), immediately before racing, 5 min post-race and 15 min post-race. In six horses, blood samples also were obtained 30 min post-race. Race times averaged 1.1 s faster after NaHCO3 treatment (P less than .1). Sodium bicarbonate treatment also elevated blood pH (P less than .05). In the horses sampled 15 and 30 min post-race, blood lactate disappearance was faster with the NaHCO3 treatment (P less than .05). The NaHCO3 may delay the fatigue precipitated by i.m. acidosis. Because other factors may limit performance (musculoskeletal soundness, cardiovascular and respiratory ability), NaHCO3 would not be expected to enhance the performance of all horses. However, the effect of NaHCO3 on lactate clearance may have implications for all intensively worked horses; because lactate and the associated hydrogen ions are believed to cause muscle damage and soreness, any mechanism to increase their removal rate could benefit the equine athlete.     

Factors Affecting Prognosis and Conversion in Equine Atrial Fibrillation

Sixty-seven horses presented with atrial fibrillation (AF) from January 1, 1980 to August 1, 1986. All horses were evaluated for the type and severity of the underlying cardiac disease and the probable duration of the arrhythmia. Fifty-two (78%) of the horses were treated with quinidine sulfate and/or digoxin. The response to treatment was assessed in each horse. Horses were followed for periods extending from 8 months to 7 years. Standardbreds, young horses, and males predominated in the study group. There were more male horses (stallions and geldings) than mares. Most horses with AF had no evidence of other cardiac disease (56.7%). All performance horses without other cardiac disease were treated, and return to performance was significantly associated with conversion to sinus rhythm. Horses that did not convert with quinidine sulfate therapy, whose arrhythmia recurred, and that had side effects from quinidine sulfate therapy, had a longer history of poor performance. Tachycardia (heart rate greater than 60 beats/min) was significantly associated with the existence of congestive heart failure. The horses with congestive heart failure had a poor prognosis for life (7.7% survived) and a poor conversion to normal sinus rhythm (23.1%). Mitral regurgitation (19 horses) was the most common underlying cardiac disease. Tricuspid regurgitation (15 horses), aortic regurgitation (3 horses), myocardial dysfunction (3 horses), and atrial septal defect (1 horse) also were diagnosed. Congestive heart failure was common in this group of horses with underlying cardiac disease.     

Management,health, and abnormal behaviors of horses: A survey in small equestrian centers in Brazil

Care conditions of horses housed in small equestrian establishments and the occurrence of health and behavioral problems were assessed in 197 animals. Based on questionnaires and direct observations of the animals, it was noted that 8% of all animals were fed exclusively on pasture, whereas 92% received commercial concentrate or grain with limited or no grass. Sixty percent of the horses spent 20-24 hours/day in the stalls, 30% spent 12 hours/day, and 10% were kept outdoors. Eighty five percent exercised regularly, whereas 15% did not exercise at all. Wounds (18%), colic (6%), and strangles (3%) were the most cited diseases in the interviews. Fifty-six percent of the horses showed behavioral problems; the frequency and type of abnormal behavior varied according to horse use (P < 0.001). The management of the horses presented numerous concerns regarding feeding and housing, probably leading to increased behavioral problems. The results presented here would be a useful tool for the education of owners and caretakers.     

Electrocardiography in the horse. (A report of findings in 138 horses)

Over a period of approx. 3 years, electrocardiograms (ECG) were recorded from 138 horses referred as patients to the Medical Clinic. Of these, 22 horses (approx. 16 per cent) has ECG alterations. The 22 ECG's revealed a total of 29 ECG abnormalities. The most frequent ECG alteration was incomplete AV block, that was seen in 9 horses (31 per cent of the ECG abnormalities). Abnormal (i.e. broad, tent-like and, sometimes, inverted) T waves and deviations of the ST segment were seen each in 5 ECG's from 7 horses, 3 of which had both abnormalities which were associated with severe underlying disease (colic, enteritis, pneumonia, strangles a.o.). Premature ventricular beats were seen in 3 horses, two of which had serious cardiovascular dysfunction whereas the third showed no signs of cardiac disease. Atrial fibrillation was observed in two horses. Both were treated with chinidine sulphate but a conversion to sinus rhythm was not achieved in either case. Other ECG abnormalities observed in the study were, parasystole (1 horse), sinus arrhythmia (2 horses), sinoatrial block (1 horse) and wandering pacemaker (1 horse). Each abnormality is discussed with regard to its clinical significance and diagnosis. Cardiac murmurs were detected on auscultation of 26 horses (approx. 19 per cent). The murmurs in 15 horses were short and faint sounds most of which were diastolic. They were considered of no importance. Eleven horses, on the other hand, had distinct, loud (grade 4 or 5), holosystolic or holodiastolic murmurs that were considered pathological. Eight of these horses had actual signs of cardiac disease. Cardiac vector distribution in patients with ECG abnormalities or murmurs showed no systematic differences from vectors in horses showing no cardiac abnormality.     

Pathomorphological study on gastroduodenal ulceration in horses: localisation of lesions

Gastroduodenal ulceration is a prevalent disease in foals and adult horses. Decreased performance as well as fatal complications relate to this syndrome. The objective of our study was to determine the prevalence of gastric ulceration in a mixed population of horses by postmortem examination and to evaluate a possible association between equine gastric ulcer syndrome (EGUS) and sex or age of the examined horses, to evaluate the localisation of lesions in the proximal part of the gastrointestinal tract and to determine the occurrence of gastric parasites. Postmortem examinations were performed on 71 horses over a period of 24 months. Gastric ulcers were found in 52 horses (73.2%). There was no significant association between age or sex and occurrence of gastric ulcers. In all horses the squamous mucosa lesions were localised near the margo plicatus (100% of the cases), whereas in 23 horses the lesions were near the margo plicatus and lesser curvature and in 7 horses at the greater curvature. In 18 horses the mucosa was affected in the whole extent of the margo plicatus and in 1 horse diffuse lesions of the squamous mucosa were noted. Lesions of the glandular mucosa were localised in 11 horses at the fundic area, in 1 horse they occurred in the pylorus, and in 10 horses diffuse lesions of the glandular mucosa were recorded. A low prevalence of Gasterophilus intestinalis infection was detected (1 horse, 1.4%). We have confirmed that gastric ulcers are a common problem in horses and duodenal or oesophageal ulceration is rare (not a single case of the latter was found in this study). Lesions in the glandular mucosa of the stomach are more frequent in suckling foals than in older animals. Lesions of the glandular mucosa are also common in adult horses, and a complete gastroscopic examination including examination of the pylorus is advisable to evaluate this syndrome.     

Measurement of ammonia concentrations in horse stalls

The effect of treating stall floors with an ammonia-absorbingcompound (AAC) on aerial ammonia levels was tested during two 14-day periods in a four-stall barn. In the first period, two stalls were treated with the AAC and the other two stalls remained as the non-treated controls. In the second period, the stalls were switched. Four geldings were used in each period and were randomly assigned to the stalls. The horses remained in the stalls at all times except for 30 min of turn-out per day at which time the stalls were cleaned. Ammonia levels at the stall floor were measured by a Bruel and Kjacr 1302 gas monitor on day 0 before the horses were admitted to the barn and on days 1, 3, 5, 7, 10 and 14. Ammonia diffusion tubes were attached to the horses' halters on days 1, 7, 11 and 13 for 8 hours to determine the level of ammonia exposed to the horse. On day 14, ammonia concentrations near the stall floor were 25% lower in treated stalls than in control stalls (P<0.1). Ammonia concentrations measured at the halter were much lower than those at the floor, but horses in treated stalls had lower ammonia exposure than horses in control stalls (P<0.1).     

Population distributions of phenylbutazone and oxyphenbutazone after oral and i.v. dosing in horses

Experiments to determine the residual plasma concentrations of phenylbutazone and its metabolites found in horses racing on a 'no-race day medication' or 24-h rule were carried out. One dosing schedule (oral-i.v.) consisted of 8.8 mg/kg (4 g/1000 lbs) orally for 3 days, followed by 4.4 mg/kg (2 g/1000 lbs) intravenously on day 4. A second schedule consisted of 4.4 mg/kg i.v. for 4 days. The experiments were carried out in Thoroughbred and Standardbred horses at pasture, half-bred horses at pasture, and in Thoroughbred horses in training. After administering the i.v. schedule for 4 days to Thoroughbred and Standardbred horses at pasture, the mean plasma concentrations of phenylbutazone increased from 0.77 microgram/ml on day 2 to 2.5 micrograms/ml on day 5. The shape of the frequency distribution of these populations was log-normal. These data are consistent with one horse in 1,000 yielding a plasma level of 8.07 micrograms/ml on day 5. After administration of the oral-i.v. schedule to Thoroughbred and Standardbred horses at pasture, the mean plasma concentrations of phenylbutazone were 3.4 micrograms/ml on day 2 and 3.5 micrograms/ml on day 5. The range on day 5 was from 1.4 to 8.98 micrograms/ml and the frequency distribution was log-normal. These data are consistent with one horse in 1000 having a plasma level of 15.8 micrograms/ml on day 5. In a final experiment, the oral dosing schedule was administered to 62 Thoroughbred horses in training. Plasma concentrations on day 5 in these horses averaged 5.3 micrograms/ml. The range was from 1.3 to 13.6 micrograms/ml and the frequency distribution was log-normal. Statistical projection of these values suggests that following this oral dosing schedule in racing horses about one horse in 1000 will yield a plasma level of 23.5 micrograms/ml of phenylbutazone 24 h after the last dose.     

Housing and use of horses in Switzerland: a representative analysis of the status quo

Out of a representative sample of 1861 Swiss horse yards, 622 horse keepers (35.2%) with 2536 horses, ponies and donkeys sent back a questionnaire about general farm characteristics, their horse-specific training, horse stock, housing conditions, intraspecific social contacts, feeding, ability to move freely, use of the horses and management. 83.5% of horses were kept individually (thereof 18.3% tethered, 32.3% in a loose box indoors, 28.4% in a loose box outdoors, and 4.5% in a loose box with permanent access to a paddock or an individual pasture), and 16.5% lived in group housing systems. 36% of the horses had daily access to a pasture, 62.8% depending on the weather, and 1.2% never at all. Individually housed horses pastured significantly less than horses kept in groups. The mean use per week was 4.5 hours, depending on breed, type of use and housing system. Only 50% of the horse keepers were trained with respect to horses or farm animals (e.g. professional training graduation, license, military service, veterinarian, farmer). In Switzerland, horses are still housed and fed in a traditional way, despite considerable recent changes in the amount and type of use (65.1% leisure horses, 34.9% sport and working horses); this may result in health and behavioural problems. Therefore, information and education of horsewomen and horsemen should be emphasized in the future. For the transfer of knowledge, veterinarians are of high importance.