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Acute vitamin D3 toxicosis in horses: case reports and experimental studies of the comparative toxicity of vitamins D2 and D3.

Acute vitamin D toxicosis was diagnosed in 2 horses fed a grain ration containing 1,102,311 IU of cholecalciferol (vitamin D3)/kg (500,000 IU/lb) for about 30 days. Horse 1 died acutely with extensive mineralization of cardiovascular and other soft tissues. Horse 2, which had severe clinical signs and clinicopathologic changes of toxicosis, was treated with nonsteroidal antiinflammatory drugs and recovered in about 6 months. In an experimental study, the toxicity of ergocalciferol (vitamin D2) and cholecalciferol was compared in 2 horses (No. 3 and 4) given the respective vitamins at a daily dosage of 33,000 IU/kg of initial (day 0) body weight for 30 days. Except for slight loss in body weight (8%) during the 1st few days of treatment, horse 3 remained clinically normal. Horse 4 developed limb stiffness and tachycardia, became anorectic, weak, and recumbent, lost 29% of body weight, and had polydipsia and polyuria. Horses 2, 3, and 4 developed persistent hyperphosphatemia. Horse 2 remained normocalcemic whereas horses 3 and 4 became hypercalcemic by day 28. In horse 3, serum vitamin D2 metabolite concentrations on days 0, 1, 14, and 26 were: vitamin D2 (ng/ml) = less than 5.0, 5.7, 71.4, and 188.0; 25-hydroxy-vitamin D2 (ng/ml) = less than 5.0, less than 5.0, 43.1, and 117.5; and 1,25-dihydroxy-vitamin D (pg/ml) = 19.7, 23.2, 25.0, and 45.7, respectively. In horse 4, serum vitamin D3 metabolite concentrations on the same days were: vitamin D3 (ng/ml) = less than 5.0, 110.0, 1,049.0, and 887.0; 25-hydroxy-vitamin D3 (ng/ml) = less than 5.0, 18.9, 201.0 and 182.0; and 1,25-dihydroxy-vitamin D (pg/ml) = 21.5, 18.9, 25.2, and 21.6, respectively. Urine of horses 2 and 4 became acidic (pH 6). Horses 2, 3, and 4 became hyposthenuric, but the decrease in urine specific gravity (sp gr) in horse 3 occurred only after 3 weeks of treatment and was only moderate (sp gr, 1.018 to 1.021) and nonprogressive. Hyposthenuria was evident in horse 4 on day 4 (sp gr, 1.028), and was progressive and marked (sp gr, days 28 to 32: 1.006 to 1.009). Urine sp gr of horse 2 ranged from 1.002 to 1.007. Fractures were demonstrated radiographically and histologically in the costochondral junctions of horses 3 and 4. Mineralization of cardiovascular and other soft tissues developed in horses 3 and 4, with lesions being more severe and having a wider tissue distribution in horse 4.

Acute Disease↗

Amino acid supplementation improves muscle mass in aged and young horses.

The objective of the study was to evaluate the effect of supplementary AA on the ability to support muscle mass in aging horses. Sixteen horses of light horse type were used in a 2 x 2 factorial arrangement of treatments with two age groups [< or = 10 yr (average = 9.1 +/- 0.29 yr) and > or = 20 yr (average = 22.4 +/- 0.87 yr)] and two diet groups [no supplementation (N) or supplementary lysine and threonine (S; 20.0 and 15 g/d, respectively)]. Horses were fed the diets for 14 wk and received regular light exercise throughout the study. Body weight, BCS, and venous blood samples were taken every 2 wk. Plasma was analyzed for total protein, albumin, creatinine, urea N (PUN), and an AA profile, including 3-methyl histidine (3MH) and sulfur AA. Photographs of the horses taken at the start and at the end of the experiment were used to assign a subjective muscle mass score from 1 to 5 (1 = lowest to 5 = highest). There was no difference in BW caused by diet; however, the S-group horses tended (P = 0.064) to gain more weight (6.91 +/- 2.3 kg), and in fact, the N-group horses lost weight (- 11.76 +/- 5.2 kg) during the experiment. Repeated measures analysis revealed that BCS was lower for the aged vs. the young horses (P = 0.001) as well as for the S- vs. the N-group horses (P = 0.026). Subjective muscle mass scores were not different at the start of the experiment but were greater (P = 0.047) for the S-group horses (3.77 +/- 0.13) at the end of the experiment compared with the N-group horses (3.28 +/- 0.14). Plasma creatinine was greater (P = 0.032), and PUN was lower (P = 0.027), for S-group horses compared with N-group horses. Initial 3MH concentrations were not different; however, at the end of the experiment, 3MH was lower for the S-group horses (P = 0.016) compared with the N-group horses. Plasma lysine and threonine concentrations were greater for S-group horses at the end of the experiment than for N-group horses (P = 0.023 and 0.009, respectively). Both 3MH and PUN concentrations were negatively correlated to lysine (R2 = 0.57 and 0.65, respectively) and threonine intake (R2 = 0.56 and 0.60, respectively) at the end of the study. These data suggest that horses receiving supplementary AA were able to maintain muscle mass better than those without supplementation, regardless of age, as evidenced by the improvement in muscle mass scores, lower BCS with no difference in BW, greater creatinine, and lower 3MH and PUN concentrations in the S-group horses.

Aging↗

Life-threatening hemorrhage from enterotomies and anastomoses in 7 horses.

OBJECTIVE: To report our experience with horses that presumptively had severe intraluminal hemorrhage from enterotomy or anastomosis. STUDY DESIGN: Clinical study. ANIMALS: Six adult horses and 1 adult donkey. METHODS: A retrospective study was conducted at the University of Illinois (April 1994 to December 2001) to determine the clinical course and outcome of horses with melena and/or anemia and evidence of life-threatening hemorrhage from intestinal incisions. Medical records of all horses that had colic surgery were reviewed to determine the proportion of horses with this complication. In addition, horses that fit the same criteria identified in 3 other veterinary clinics were included. RESULTS: Three horses (1.3%) of those that had enterotomy or anastomosis at the University of Illinois and 4 horses from other clinics had complications presumptively related to severe hemorrhage from these intestinal procedures. Melena became evident within 72 hours of surgery and lasted 12 to 96 hours. Six horses had an acute and severe drop in packed cell volume (PCV), increased heart rates, and other signs of acute hemorrhage, and 1 horse had signs of colic postoperatively. Horses were administered intravenous formalin (3 horses) and whole blood transfusions (4 horses). Repeat celiotomy was performed on 2 horses. In 1 of these horses, a bleeding artery was ligated in the edge of the original enterotomy, and, in the other, a 25-cm-diameter intraluminal blood clot was found occluding the pelvic flexure. A horse that had jejunocolostomy for cecal impaction was not treated for hemorrhagic shock but was euthanatized and necropsied. Necropsy revealed blood-filled bowel from the jejunocolostomy to the anus. One of the remaining 6 horses died of enterocolitis and 5 survived to discharge. CONCLUSIONS: Hemorrhage from incisional edges, particularly in the large intestine, should be considered a rare but possibly fatal complication of enterotomy or anastomosis in horses. CLINICAL RELEVANCE: To prevent fatal hemorrhage from incisional edges during enterotomy or anastomosis, large vessels should be ligated at the original surgery, and hemostatic effects of different closure techniques should be considered. No intraoperative or postoperative findings were useful to predict this complication, and response to supportive medical therapy was favorable.

Anastomosis, Surgical↗

Aorto-cardiac fistulas in seven horses.

This report describes the history, clinical, electrocardiographic and echocardiographic findings, treatment, outcome and post-mortem findings in seven horses with aorto-cardiac fistula. Affected horses included 5 stallions, one gelding and one mare; 2 each of the Thoroughbred, Arabian and Standardbred breeds and one Thoroughbred-cross with a mean +/- s.d. age of 12 +/- 4 years, range 6-18 years. The presenting signs were acute distress (four horses), exercise intolerance (two horses) and the lesion was detected during a routine examination in one horse. Five horses had monomorphic ventricular tachycardia on admission and one other had a history of this arrhythmia. Five horses had a characteristic continuous murmur loudest in the right fourth intercostal space. Echocardiography (six horses) and/or post-mortem examination (four horses) revealed the horses had aorto-cardiac fistulas arising from the right aortic sinus in all five horses in which the site was recorded. Two horses had ruptured aneurysmal dilatations of the aortic wall at this site. Fistulas extended into the right ventricle in four horses; the right atrium in two horses, the left ventricle in one horse, and five horses had dissecting tracts in the septal myocardium. Horses survived for periods ranging from 24 h to 4 years. Aorto-cardiac fistula should be considered in the differential diagnosis for horses presenting with acute distress, bounding arterial pulse, a right-sided continuous murmur and/or monomorphic ventricular tachycardia, particularly in middle-aged or older stallions. Echocardiography is the technique of choice for confirming the diagnosis and demonstrating accompanying cardiac changes.

Age Factors↗

Transmission studies of Hendra virus (equine morbillivirus) in fruit bats, horses and cats.

OBJECTIVE: To determine the infectivity and transmissibility of Hendra virus (HeV). DESIGN: A disease transmission study using fruit bats, horses and cats. PROCEDURE: Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second experiment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experiment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody. RESULTS: Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated developed acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas. CONCLUSIONS: Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus to horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.

Administration, Intranasal↗

In vitro of adenosine on lymphocytes and erythrocytes from horses with combined immunodeficiency.

The effect of adenosine on the mitogenic response of peripheral blood lymphocytes (PBL) and on the nucleotide pools of erythrocytes from normal horses, horses heterozygous for the combined immunodeficiency (CID) trait (carriers), and foals with CID was studied. When PBL from normal, carrier, and CID horses were stimulated by phytohemagglutinin (PHA), concanavalin A, or pokeweed mitogen, [3H]thymidine uptake was inhibited by adenosine (0.1 microM) to 1.0 mM) in a dose-dependent manner. Adenosine (100 microM) mediated inhibition of [3H]thymidine uptake was prevented in both normal and carrier horse PBL by incubation with uridine. Uridine had no sparing effect on PBL from horses with CID. Differences were detected between human and horse PBL in response to adenosine and erythro-9(2-hydroxy-3-nonyl) adenine (EHNA), a competitive inhibitor of adenosine deaminase. In the first assay, mitogen-stimulated PBL from horses were more sensitive to adenosine. In the second assay, adenosine was added to PBL cultures at various times after PHA addition. Adenosine inhibited mitogenesis in horse PBL if added within the first 24 h. In human PBL cultures, adenosine inhibited mitogenesis only if added within the first 4 h. The third assay measured capacity of PHA-stimulated human and horse lymphocytes to escape inhibition by adenosine or EHNA. At the end of a 72-h culture period, horse PBL were still inhibited of mitogenesis in both human and horse PBL. With prolonged incubation (72 h), synergistic inhibition was detected only in horse PB. With high-pressure liquid chromatography, nucleotide levels in erythrocytes of normal, carrier, and CID horses were found to be similar. Incubation with adenosine produced a 1.5- to 2-fold increase in total adenine nucleotide pools in erythrocytes from all horses. However, these increases were accompanied by alterations in the relative amounts of the nucleotide components. This was seen as a significant decrease in the ATP:(AMP plus ADP plus ATP) ratio and energy charge in erythrocytes from normal horses. In contrast, the ATP:(AMP plus ADP plus ATP) ratio decreased only slightly in erythrocytes from CID horses, whereas no change in the energy charge was detected. The data from these studies indicate a difference in adenosine metabolism exists between human and horse lymphoyctes, and an abnormality may exist in purine metabolism or in an interconnecting pathway in horses with CID.

Adenine↗

Evaluation of risk factors for development of catheter-associated jugular thrombophlebitis in horses: 50 cases (1993-1998).

OBJECTIVE: To evaluate risk factors associated with development of catheter-associated jugular thrombophlebitis in hospitalized horses. DESIGN: Retrospective case-control study. ANIMALS: 50 horses with thrombophlebitis and 100 control horses. PROCEDURE: Medical records from 1993 through 1998 were searched for horses with thrombophlebitis. Horses that were hospitalized for at least 5 days, had an i.v. catheter placed in a jugular vein (other than for solely anesthetic purposes), and had no evidence of thrombophlebitis during admission or hospitalization were chosen as controls. Signalment, history, clinicopathologic findings, primary illness, and treatment were obtained from the medical records. Data were analyzed by use of logistic regression to perform univariate and multivariate analyses. RESULTS: For a horse with endotoxemia, the odds of developing thrombophlebitis were 18 times those for a similar horse without endotoxemia. For a horse with salmonellosis, the odds of developing thrombophlebitis were 68 times those for a similar horse without salmonellosis. For a horse with hypoproteinemia, the odds of developing thrombophlebitis were almost 5 times those for a similar horse without hypoproteinemia. For a horse in the medicine section, the odds of developing thrombophlebitis were 16 times those for a similar horse in the surgery section. For a horse with large intestinal dise, the odds of developing thrombophlebitis were 4 times those for a similar horse without large intestinal disease. For a horse receiving antidiarrheal or antiulcerative medications, the odds of developing thrombophlebitis were 31 times those for a similar horse not receiving these medications. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that patient factors, including large intestinal disease, hypoproteinemia, salmonellosis, and endotoxemia, were associated with development of catheter-associated thrombophlebitis in horses.

Animals↗

Treatment of horses with chronic diarrhea: immunologic status.

All chronically diarrheal horses given (orally) 2 series of treatments with normal horse serum recovered in 2 to 4 weeks. However, mild diarrhea sometimes persisted several months in the group of horses with severe diarrhea. Weight gains were approximately 35% in horses with severe diarrhea and approximately 10% in horses with mild diarrhea. Serum specimens from 12 diarrheal and 20 normal horses were examined for immunoglobulins by single radial immunodiffusion technique. Concentration of immunoglobulin A in serum of diarrheal horses was approximately 50% lower than that in serum of normal horses. By contrast, there was more immunoglobulin G in serum of diarrheal horses than in serum of normal horses. Phytohemagglutinin (PHA-M) responsiveness of blood lymphocytes showed transient suppression during the stage of severe diarrhea. The regaining of PHA-M responsiveness of lymphocytes was observed simultaneously with the recovery process. However, the responsiveness of lymphocytes in recovered horses remained markedly lower than that in normal horses. Allergic reactions in diarrheal and normal horses were studied by observing dermal response to injections of saline extracts from some of the horse feeds. A delayed hypersensitivity reaction to streptokinase-streptodornase and PHA-M was also studied. Allergic reactions to these extracts were not induced in either diarrheal or normal horses; however, inflammatory response to the extracts was approximately 50% greater in normal than in diarrheal horses. Response to intradermal injection of either streptokinase-streptodornase or PHA-M was significantly greater in normal horses than in diarrheal horses.

Animals↗

Loop colostomy for management of rectal tears and small-colon injuries in horses: 10 cases (1976-1989).

Loop colostomy was performed in 10 horses as treatment for grade-III rectal tears (n = 6 horses), small-colon infarction (n = 2 horses), perirectal abscess and stenosis (n = 1 horse), and small-colon stricture (n = 1 horse). In 7 horses, the colostomy was constructed through a single incision low in the left flank, with closure of the incision around the stoma (single-incision technique). In 3 horses, 2 of which had colostomy performed as a standing procedure, the selected segment of small colon was placed from a flank incision into a separate, small incision low in the left flank (double-incision technique). Five horses underwent colostomy reversal (at 18 to 63 days) and 2 of these horses, both with grade-III rectal tears, recovered completely. Of 8 horses that did not survive, 6 died from the primary disease or associated complications. Technical problems associated with colostomy accounted for death of 2 horses. One horse had gastric rupture attributable to suture occlusion of the small intestine after colostomy reversal, and another horse had complications of incisional infection after repair of a peristomal hernia. Small-colon prolapse through the stoma necessitated premature reversal of the colostomy in a horse that was euthanatized because of worsening laminitis. Minor complications of the colostomy procedure were partial stomal dehiscence (n = 4 horses), partial dehiscence of the flank wound after colostomy reversal (n = 2 horses), and small ventral midline hernia after colostomy reversal (n = 1 horse). Loop colostomy may be of benefit to horses with rectal tears, provided it is done soon after the tear occurs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Acid:base and serum biochemistry changes in horses competing at a modified 1 Star 3-day-event.

We examined the effects of participation in each of 3 modifications of Day 2 of a 3-day-event on blood and serum variables indicative of hydration, acid:base status and electrolyte homeostasis of horses. Three groups of horses - 8 European (E) horses and 2 groups each of 9 North American horses performed identical Days 1 (dressage) and 3 (stadium jumping) of a 3-day-event. E horses and one group of the North American horses (TD) performed modifications of Day 2 of a 1 Star 3-day-event and the other group of North American horses (HT) performed a Horse Trial on Day 2. Jugular venous blood was collected from each horse on the morning of Day 2 before any warm-up activity, between 4 min 55 s and 5 min 15 s after Phase D and the following morning. Eight E horses, 5 TD horses and 8 HT horses completed the trials. There were few significant differences in acid:base or serum biochemistry variables detected among horses performing either 2 variations of the Speed and Endurance day of a 1 Star 3-day-event, or a conventional Horse Trial. Failure to detect differences among groups may have been related to the low statistical power associated with the small number of horses, especially in the TD group, variation in quality of horses among groups and the different times of the day at which the E horses competed. Differences detected among time points were usually common to all groups and demonstrated metabolic acidosis with a compensatory respiratory alkalosis, a reduction in total body water and cation content, and hypocalcaemia. Importantly, horses of all groups did not replenish cation, chloride, and calcium deficits after 14-18 h of recovery.

Acid-Base Equilibrium↗

Characterization of Escherichia coli isolated from adult horses with and without enteritis.

In the present study E. coli strains isolated from the faeces of ten horses with diarrhoea and 14 horses without diarrhoea were characterized. All horses were culture negative for Salmonella species. Nine colonies of E. coli from each faecal sample were picked at random and a DNA fingerprint was made by means of a polymerase chain reaction (PCR) using Enterobacterial Repetitive Intergenic Consensus (ERIC) primers. The number of E. coli genotypes did not differ significantly between horses with and without diarrhoea. In addition, all E. coli strains with different DNA fingerprints were tested by PCR for genes encoding the virulence factors K88, F41, F17, CS31a, Sta1, LT1, VT2, CNF, BFP, and intimin. Genes coding for K88, F41, BFP, STa1, VT2, and CS31A were not detected. Genes for CNF were found in strains from one horse with diarrhoea and one horse with normal faeces. Genes for LT1 (n=1) and intimin (n=1) were found only in strains from horses with normal faeces. Genes for F17 fimbriae were found in strains from three horses with diarrhoea (30%) and in none of the strains from healthy horses. In two of these horses, E. coli strains with different DNA polymorphism patterns were F17 positive; however, none of these strains possessed LT1, Sta1, or CNF genes. Haemolytic E. coli strains were only isolated from two horses with diarrhoea and from none of the healthy horses. Nineteen percent of all E. coli strains did not ferment lactose. Eight per cent of these lactose-negative strains were from horses with diarrhoea, whereas 32% were from horses without diarrhoea. In conclusion, virulence factors were present in E. coli isolates from horses with and without diarrhoea, except for F17, which was only found in E. coli isolated from horses with diarrhoea. F17-positive E. coli might have importance as cause of diarrhoea in horses, but further studies are needed.

Animals↗

The prevalence of laryngeal disease in a large population of competition draft horses.

OBJECTIVES: (1) To determine the effect of age, height, weight, breed, sex, and specific use on the prevalence of idiopathic left laryngeal hemiplegia (ILH) in a population of draft performance horses; (2) to determine the association between tracheal mucus and laryngeal dysfunction, and the prevalence of exercise-induced pulmonary hemorrhage (EIPH) in a population of draft performance horses. STUDY DESIGN: Cross-sectional. ANIMALS: Draft horses competing at the 2005 Michigan Great Lakes Draft Horse Show. METHODS: Endoscopic examinations were performed on horses competing at the 2005 Michigan Great Lakes Draft Horse Show. Signalment, height, and weight were obtained from the owners and trainers. RESULTS: Belgian, Percheron, and Clydesdale horses (n=183) were studied. Prevalence of ILH was 35%. Horse height was significantly associated with the risk of ILH in Belgian and Percheron horses but not Clydesdales. There was a significantly different prevalence of ILH among the breeds such that 42% Belgians, 31% Percherons, and 17% Clydesdales were affected. Laryngeal disease was a risk factor for increased tracheal mucus. None of the horses had acute evidence of EIPH. CONCLUSIONS: The prevalence of ILH in draft horses has increased or is higher in competition horses compared with previously studied groups. Tracheal and/or pulmonary inflammation may be more common in draft horses with ILH based on our findings that horses with ILH have more tracheal mucus than horses with normal laryngeal function. CLINICAL RELEVANCE: Selection pressure for large, taller, longer-necked horses may be responsible for a seemingly increased incidence of ILH in competitive draft horses.

Animals↗

Acceptability of a paste formulation and efficacy of high dose omeprazole in healing gastric ulcers in horses maintained in race training.

Gastric ulceration has been found to occur in 80-90% of Thoroughbreds in active race training. Previously, variable success has been reported using mucosal surface protectants and H2 receptor antagonist. Omeprazole, a substituted benzimidazole, has been shown to inhibit gastric acid secretion in both man and animals. Fourteen horses, in active race training and with endoscopic evidence of moderated to severe gastric ulceration were divided into 2 groups: Group 1 (7 horses) were given placebo paste orally once daily for 28 days; Group 2 (7 horses) received 1.54 g active omeprazole in the placebo once daily for 28 days. Logs detailing administration and acceptability of the paste, and the horse's feeding and training regime were maintained by the trainer of each horse. Endoscopic examination of the stomach occurred at the beginning of the trial, and at 13-17 days and 27-31 days following commencement of the trial. Those horses that were free of ulceration on Days 27-31 were reexamined on Days 35-49. Acceptability of the paste, whether with or without active omeprazole, was deemed excellent in all horses except on one occasion, when one horse swallowed the paste following initial mild reluctance. Of the horses given the placebo (Group 1), 3 were withdrawn after the 13-17 day endoscopic examination: 1 horse to be given a H2 receptor antagonist, 1 horse was removed from training due to aryepiglottic entrapment and 1 horse had a greater than 10% fall in bodyweight from the start of the trial. Of the horses given active omeprazole (Group 2), one horses was relocated to another race track following the 13-17 day endoscopic examination. For the horses given placebo (Group 1), there was no change in the severity of ulceration. In contrast, the severity of ulceration in the horses given active omeprazole was significantly reduced at 13-17 days and 27-31 days. In 2 Group 2 horses, ulcers that had been completely eliminated subsequently returned when reexamined at 35-49 days. The results of this study suggest that omeprazole, employing a once daily dosing schedule, is effective at reducing the severity or eliminating gastric ulcers in Thoroughbreds in active race training.

Administration, Oral↗

Effects of phenylbutazone alone or in combination with flunixin meglumine on blood protein concentrations in horses.

OBJECTIVE: To assess effects of treatment with phenylbutazone (PBZ) or a combination of PBZ and flunixin meglumine in horses. ANIMALS: 24 adult horses. PROCEDURE: 13 horses received nonsteroidal antiinflammatory drugs (NSAIDs) in a crossover design. Eleven control horses were exposed to similar environmental conditions. Treated horses received PBZ (2.2 mg/kg, PO, q 12 h, for 5 days) and a combination of PBZ and flunixin meglumine (PBZ, 2.2 mg/kg, PO, q 12 h, for 5 days; flunixin meglumine, 1.1 mg/kg, IV, q 12 h, for 5 days). Serum samples were obtained on day 0 (first day of treatment) and day 5, and total protein, albumin, and globulin were measured. RESULTS: 1 horse was euthanatized with severe hypoproteinemia, hypoalbuminemia, and colitis during the combination treatment. Comparisons revealed no significant difference between control horses and horses treated with PBZ alone. There was a significant difference between control and treated horses when administered a combination of PBZ and flunixin meglumine. Correction for horses with values >2 SDs from the mean revealed a significant difference between control horses and horses administered the combination treatment, between control horses and horses administered PBZ alone, and between horses receiving the combination treatment and PBZ alone. Gastroscopy of 4 horses revealed substantial gastric ulcers when receiving the combination NSAID treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of the study indicates the need for caution when administering a combination NSAID treatment to horses because the detrimental effects may outweigh any potential benefits.

Animals↗

Assessment of clinical characteristics, management practices, and activities of geriatric horses.

OBJECTIVE: To describe the demographic and clinical characteristics, management practices, and owner perception of a population of geriatric horses, and to compare these data with findings in a group of younger horses. DESIGN: Original study. ANIMALS: 218 horses. PROCEDURE: Data were collected via a survey tool from owners of 165 horses that were > or = 20 years of age and 53 horses that were < 20 years of age. RESULTS: Compared with young horses, the geriatric group included a significantly greater number of ponies; geriatric horses were also more likely to have a history of colic, dental disease, tumors, lameness, and pituitary disease, but not laminitis, diarrhea, allergies, respiratory tract disease, thyroid disease, or fractures. Horses that had participated in Western equestrian disciplines were more likely to have a history of lameness. Among old horses, those with pituitary dysfunction were more likely to have a history of laminitis than those without pituitary dysfunction. Geriatric horses were more likely to have long hair and shedding abnormalities than were younger horses. Owners perceived their horses as old at approximately 22 years of age. In horses older than 16.5 years of age, age was a negative factor in the purchase of horses. CONCLUSIONS AND CLINICAL RELEVANCE: Geriatric and young horses share some similar health problems, but old horses have distinct health problems and veterinary medical requirements. The management and athletic history of horses may influence health as they age.

Age Distribution↗

Lameness in 46 horses associated with deep digital flexor tendonitis in the digit: diagnosis confirmed with magnetic resonance imaging.

REASONS FOR PERFORMING STUDY: The differential diagnosis of foot pain has long proved difficult and the use of magnetic resonance imaging (MRI) offers the opportunity to further the clinical understanding of the subject. OBJECTIVES: To determine the incidence of deep digital flexor tendon (DDFT) injuries in a series of 75 horses with lameness associated with pain localised to the digit, with no significant detectable radiographic or ultrasonographic abnormalities, using MRI; and to describe a variety of lesion types and relate DDF tendonitis with anamnesis, clinical features, response to local analgesic techniques and nuclear scintigraphic and ultrasonographic findings. METHODS: All horses undergoing MRI of the front feet between January 2001 and October 2002 were reviewed and those with DDFT injuries categorised according to lesion type; horses with primary tendonitis (Group I) and those with concurrent abnormalities of the navicular bone considered to be an important component of the lameness (Group II). The response to perineural analgesia of the palmar digital nerves and palmar (abaxial sesamoid) nerves, intra-articular analgesia of the distal interphalangeal (DIP) joint and analgesia of the navicular bursa were reviewed. The result of ultrasonography of the pastern and foot was recorded. Lateral, dorsal and solar pool and bone phase nuclear scintigraphic images were assessed subjectively and objectively using region of interest (ROI) analysis. RESULTS: Forty-six (61%) of 75 horses examined using MRI had lesions of the DDFT considered to be a major contributor to lameness. Thirty-two horses (43%) had primary DDFT injuries and 14 (19%) a combination of DDF tendonitis and navicular bone pathology. Lesions involved the insertional region of the tendon alone (n = 3), were proximal to the navicular bone (n = 23) or were at a combination of sites (n = 20). Lesion types included core lesions, focal and diffuse dorsal border lesions, sagittal plane splits, insertional injuries and lesions combined with other soft tissue injuries. Many horses had a combination of lesion types. Lameness was abolished by palmar digital analgesia in only 11 of 46 horses (24%). Twenty-one of 31 horses (68%) in Group I showed > 50% improvement in lameness after intra-articular analgesia of the DIP joint, whereas 11 of 12 horses (92%) in Group II had a positive response. Twelve of 18 horses (67%) in Group I had a positive response to analgesia of the navicular bursa. Nineteen horses had lesions of the DDFT extending proximal to the proximal interphalangeal joint seen using MRI, but these were identified ultrasonographically in only 2 horses. Scintigraphic abnormalities suggestive of DDFT injury were seen in 16 of 41 horses (41%), 8 in pool phase images and 8 in bone phase images. CONCLUSIONS AND POTENTIAL RELEVANCE: DDFT injuries are an important cause of lameness associated with pain arising from the digit in horses without detectable radiographic abnormalities. Lameness is not reliably improved by palmar digital analgesia, but may be improved by intra-articular analgesia of the DIP joint in at least 68% of horses. Ultrasonography is not sensitive in detecting lesions of the DDFT in the distal pastern region, but a combination of pool and bone phase scintigraphic images of the digit is helpful in some horses. Further follow-up information is required to determine the prognosis for horses with lesions of the DDFT in the digit and to establish whether this is related to lesion severity and/or location.

Analgesia↗

Lameness associated with foot pain: results of magnetic resonance imaging in 199 horses (January 2001--December 2003) and response to treatment.

REASONS FOR PERFORMING STUDY: The diagnosis of foot-related lameness often remains elusive and it can be difficult to offer rational treatment, or to predict outcome. OBJECTIVES: To describe the spectrum of injuries of the foot identified using magnetic resonance imaging (MRI), to determine their relative prevalence among MRI diagnoses and to establish the long-term results of treatment. METHODS: The MR images of horses examined from January 2001--December 2003 were reviewed. Horses were selected for MRI if the pain causing lameness was localised to the foot using perineural analgesia but any clinical, radiological or ultrasonographic abnormalities were insufficient to explain the degree of lameness. The clinical significance of lesions identified using MRI was determined with reference to the results of local analgesia, radiography, ultrasonography and nuclear scintigraphy. Follow-up information was obtained in January 2004 for horses which had been examined 6-36 months previously and the outcome classified as excellent (horse returned to full athletic function without recurrent lameness), moderate (sound, but only in light work), or poor (persistent or recurrent lameness). RESULTS: One hundred and ninety-nine horses underwent MRI examinations. Deep digital flexor (DDF) tendonitis was the most common injury (59%) with primary injury in 65 horses (33%) and a further 27 horses (14%) having lesions of the DDF tendon and navicular bone. Seventeen percent of horses had injuries to multiple structures, including 24 with DDF tendonitis. Desmitis of a collateral ligament (CL) of the distal interphalangeal (DIP) joint was the second most common injury (62 horses, 31%), with primary injuries in 30 horses (15%) and a further 32 horses (16%) that had CL desmitis in conjunction with other injuries. Prognosis was best for horses with traumatic injuries of the middle or distal phalanges, with 5 of 7 horses (71%) having an excellent outcome. Horses with primary lesions of the DDF tendon or CL of the DIP joint had excellent results in only 13 of 47 (28%) and 5 of 17 horses (29%), respectively. Horses with combined injuries of the DDF tendon and navicular bone, or primary navicular bone abnormalities, had a poor outcome, with the majority of horses suffering persistent lameness. CONCLUSIONS: A wide variety of lesions associated with foot pain were identified using MRI, a high proportion of which were primary soft tissue injuries with a guarded prognosis for return to full athletic function. POTENTIAL RELEVANCE: It is now possible to propose more rational treatment strategies for the variety of foot injuries identified using MRI than had previously been possible; however, further information concerning aetiopathogenesis of these injuries is needed to improve their management.

Animals↗

[Pulmonary artery wedge pressure and heart rate measurement during pharmacological stress induction for left cardial function diagnosis in horses with and without heart disease].

In 18 horses, the pulmonary artery wedge pressure and the heart rate were measured during pharmacological stress load. 12 horses were healthy (4 trained, 8 untrained) and 6 horses had a heart disease (3 trained, 3 untrained). Pharmacological stress induction was carried out with the sympathomimetic drug dobutamine at a dosage rate of 7.5 microg/kg/min over 10 minutes of infusion. At the fourth minute, the parasympatholytic drug atropine was administered (5 microg/kg bw), and the heart rate and the pulmonary artery wedge pressure were continuously measured over 26 minutes. During sole dobutamine infusion, a significant decrease in heart rate and a significant increase in pulmonary artery wedge pressure were observed. After the application of atropine in the fourth minute, a significant increase in heart rate (from 35.7 +/- 6 up to 106 +/- 38/ min) and in pulmonary artery wedge pressure (from 15.7 +/- 3 up to 24 +/- 8.6 mmHg) were visible in the group of healthy horses. The horses with heart diseases had a significantly higher increase in both parameters (heart rate and pulmonary artery wedge pressure) with a significantly positive correlation (r = 0.7). The heart rate increased in the horses with heart diseases from 35.2 +/- 2,8 beats/min up to 132 +/- 45.7 beats/min and the pulmonary artery wedge pressure increased from 17.3 +/- 3,2 mmHg up to 32.7 +/- 13 mmHg. The cardiac status (healthy or heart disease) as well as the training level of the horses (untrained or trained) had a significant influence on the heart rate and the pulmonary artery wedge pressure. The untrained horses (healthy and heart disease) showed significantly higher values over a longer period of time than did the trained horses with the same cardiac status. Additionally the influence of pharmacological stress induction on echocardiographic parameters was investigated. The left atrial size (p = 0.015) and left ventricular diameter were significanly different in the systole (p = 0.008) and in the diastole (p = 0.001) between healthy horses and horses with heart diseases. All horses showed a positive correlation between the pulmonary artery wedge pressure and the left atrial size (r = 0.8), as well as between the left ventricular systolic (r = 0.6) and the diastolic diameter (r = 0.6). The correlation between the pulmonary artery wedge pressure and the left atrial size was nearly the same in the healthy horses (r = 0.74) and in the horses with heart diseases (r = 0.76). Regarding the training level, all untrained horses had a significantly higher correlation between the pulmonary artery wedge pressure and the left atrial size (r = 0.87) in comparison to the trained horses (r = 0.74). Particularly in the untrained horses with heart diseases, this correlation was remarcable (r = 0.99).

Animals↗