Equine veterinary journal. Supplement最新文献

Reasons for performing study: Gastric impaction in the horse is poorly described in the veterinary literature.

Objectives: To review the clinical and pathological features of gastric impaction.

Methods: The clinical details of horses presenting with colic over a 7-year period and cases in which gastric impaction was considered to determine the outcome were reviewed. Clinical and clinicopathological data were recorded.

Results: Twelve cases of gastric impaction were recorded (1.4% of 857 horses hospitalised for colic). Diagnosis was achieved by ultrasonographic examination, gastroscopy, exploratory celiotomy and/or post mortem examination. Five out of 12 horses were successfully treated, 5/12 were subjected to euthanasia (3 at celiotomy and 2 due to recurrence of impaction) and 2/12 died. Three out of 12 horses had spontaneous gastric rupture despite attempted treatment (one was subjected to euthanasia at celiotomy and 2 died). Post mortem examination (7 horses) revealed gross muscular thickening of the stomach wall in 6/7 horses. Histological examination revealed focal fibrosis of the stomach wall in 4/6 and focal myositis in 1/6 horses. CONCLUSIONS AND PRACTICAL SIGNIFICANCE: Gastric impaction is a rare cause of colic and affected horses can present with acute, chronic or recurrent colic in the presence or absence of other gastrointestinal disease. Spontaneous gastric rupture may occur. A proportion of affected horses have gross thickening of the muscular layers of the stomach wall.

Reasons for performing study: There is a consensus in the veterinary literature that Parascaris equorum (ascarid) impaction carries a poor prognosis. Hence surgery is often delayed and foals are often subjected to euthanasia after diagnosis of ascarid impaction is established. Our clinical impression was that ascarid impaction carries a better prognosis than previously reported.

Objectives: Our expectation was that manually evacuating the impaction into the caecum, thus refraining from opening the small intestine, would improve the prognosis for survival of horses with ascarid impaction. The aim of this study was to examine medical records of horses treated surgically for ascarid impaction, record their clinical findings and evaluate the association of outcome with the method of relieving the impaction.

Methods: The medical records of all horses presented to our hospital between October 2002 and December 2011 that underwent exploratory celiotomy for ascarid impaction were reviewed. Information retrieved from the medical record included surgical findings, surgical technique, complications, short- and long-term survival. The association between categorical variables was assessed using the Fisher's exact test. A P value < 0.05 was considered statistically significant.

Results: Fifteen horses fulfilled the inclusion criteria. Eighty percent of horses (12/15) survived to discharge and 60% (6/10) survived for at least one year. Five horses are doing well but are still in convalescence. Horses that underwent small intestinal enterotomy or resection and anastomosis (n = 5) were less likely to survive to discharge (P = 0.022).

Conclusions: In our study, manual evacuation of ascarid impaction into the caecum, while refraining from opening the small intestine resulted in significantly improved survival in horses with ascarid impaction.

Potential relevance: Refraining from opening the small intestine may be the key to improving surgical outcome in horses with ascarid impaction.

Reasons for performing study: Reductions in distances between dorsal spinous processes on radiographs are used as criteria for the diagnosis of impingement of the thoracic dorsal spinous processes in horses but are potentially altered by spine motion and different head and neck positions.

Objectives: To determine the influence of head and neck positions on intervertebral distances between dorsal spinous processes on radiographs of thoracic spines of clinically sound horses.

Methods: Lateral-lateral radiographs were obtained from 23 horses in 3 head and neck positions. The width of the thoracic dorsal spinous processes and intervertebral distances between adjacent thoracic dorsal spinous processes were measured at points perpendicular to a tangent between the dorsal spinous processes and the caudal extremity of the thoracic vertebrae.

Results: A low head and neck position increased intervertebral distances between adjacent thoracic dorsal spinous processes from the 8th to 15th dorsal spinous processes whereas a high head and neck position had the opposite effect (P < 0.05). Overall, intervertebral distances between adjacent thoracic dorsal spinous processes decreased from cranial to caudal in intermediate head and neck positions (P < 0.01). The 12th thoracic dorsal spinous process was readily identifiable due to its significant difference to the narrower cranial and broader caudal dorsal spinous process (P < 0.05).

Conclusions: The head and neck position influences the distances between the dorsal spinous processes of the vertebrae of equine thoracic spine on radiography.

Potential relevance: The measuring system reported here offers potential to improve and standardise radiographic evaluation of thoracic dorsal spinous processes.

Reasons for performing the study: To investigate causes of respiratory noises in horses following prosthetic laryngoplasty (with or without a ventriculocordectomy) and to examine potential associations between degree of arytenoid abduction and the presence of other upper respiratory tract (URT) abnormalities, including right-sided collapse.

Methods: Clinical records and dynamic videoendoscopic recordings were examined from horses presented between 1995 and 2010 for investigation of respiratory noise during exercise, following a prosthetic laryngoplasty (+/- a ventriculocordectomy). Relationships between the degree of left arytenoid cartilage abduction and the presence of other URT disorders were investigated.

Results: Thirty horses matched the inclusion criteria. All horses had previously undergone a prosthetic laryngoplasty in different hospitals and in 63% (19/30) of these horses a left-sided ventriculocordectomy had also been performed. The majority of cases (87%) had multiple respiratory abnormalities and only 13% had a single URT disorder. Palatal dysfunction was the most common diagnosis (83%), followed by axial deviation of the aryepiglottic folds (60%) and vocal cord collapse (43%). The right arytenoid cartilage was fully abducted in all cases and no statistically significant correlation between the degree of left arytenoid abduction and any other URT disorders was detected.

Conclusions: Multiple forms of dynamic URT disorders were diagnosed in horses that presented with abnormal respiratory noise following laryngoplasty. There was no association between degree of left arytenoid abduction and other URT abnormalities. Furthermore, horses with suboptimal left arytenoid cartilage abduction were not predisposed to right-sided laryngeal collapse.

Clinical relevance: Our results demonstrate the fundamental role of dynamic endoscopy in correctly diagnosing dynamic airway collapse in horses that have undergone surgical treatment of the upper respiratory tract.

Reasons for performing study: Imidocarb dipropionate is the drug of choice for equine piroplasmosis but its administration causes severe colic and diarrhoea. An imidocarb protocol that reduces these effects is needed.

Objectives: 1) Quantification of the effects of imidocarb dipropionate on equine orocaecal transit time (OCTT), with and without atropine or glycopyrrolate premedication and 2) investigation of an improved pretreatment regimen for imidocarb administration.

Hypothesis: Treatment with imidocarb dipropionate will result in colic and reduced OCTT as demonstrated by the lactose 13C-ureide breath test which will be ameliorated by premedication with either atropine or glycopyrrolate.

Methods: The effects of 3 drug therapies on OCTT were compared in 6 healthy horses in a randomised double-blind study vs. a saline control: 1) imidocarb dipropionate 2.4 mg/kg bwt administered intramuscularly (i.m.) with saline administered intravenously (i.v.; imidocarb/saline); 2) imidocarb dipropionate 2.4 mg/kg bwt administered i.m. with atropine 0.035 mg/kg bwt administered i.v. (imidocarb/atropine) and 3) imidocarb dipropionate 2.4 mg/kg bwt administered i.m. with glycopyrrolate 0.0025 mg/kg bwt administered i.v. (imidocarb/glycopyrrolate). The lactose 13C-ureide breath test was used to measure OCTT in each case and significance of treatment effect determined by a linear model analysis of variance.

Results: Imidocarb/atropine treatment caused an increase in OCTT (P < 0.05) whereas imidocarb/saline produced a nonsignificant decrease in OCTT. Imidocarb/saline caused colic and diarrhoea in 4 of 6 horses, which were not seen in any of the horses treated with imidocarb/atropine or imidocarb/glycopyrrolate or administered the saline control. Intestinal borborygmi were increased in imidocarb/saline and decreased in imidocarb/atropine treated horses, respectively.

Conclusions: Imidocarb/saline treatment induced colic signs and a potential reduction in OCTT while imidocarb/atropine treatment increased OCTT significantly when compared with imidocarb/saline. Both atropine and glycopyrrolate premedication ameliorated the clinical gastrointestinal effects of imidocarb but atropine produced significant inhibition of gastric and/or small intestinal motility not detected with glycopyrrolate. Premedication with glycopyrrolate is recommended when using imidocarb for treatment of equine piroplasmosis.

Reasons for performing the study: Prior to the start of endogenous production of immunoglobulins (Igs), absorption of maternal Igs is important to protect against pathogens in the early neonatal period. It is possible that mare- or foal-associated factors may influence neonatal IgA concentrations.

Objectives: The temporal relationships among serum and milk IgA concentrations in Thoroughbred mare-foal pairs were explored to determine if periparturient mare- and foal-associated factors contribute to the prediction of foal serum IgA concentrations.

Methods: Blood and milk samples as well as complete veterinary records, were collected for 84 Thoroughbred mare-foal pairs from one month before to 2 months after parturition. Samples were tested using enzyme-linked immunosorbent assay (ELISA) for concentrations of IgA. Pairwise correlation coefficients were estimated (P < 0.01) and simple linear regression used to investigate unconditional associations between mare IgA levels, mare and foal risk factors and foal serum IgA concentration at 12 h. Backwards, stepwise elimination of nonsignificant factors was used to create a final model.

Results: There were significant temporal relationships among mare serum IgA and among colostrum and milk IgA concentrations within mares (P < 0.01). Mare serum IgA concentrations up to one month before parturition were associated with foal serum IgA concentrations at all time points and with colostrum and milk IgA concentrations. Mare serum IgA at -28 days and parity were associated with foal serum IgA concentration at 12 h (P < 0.001).

Conclusions: Mare serum IgA concentrations up to 28 days before parturition, together with mare parity, are indicative of neonatal foal serum IgA concentrations.

Potential relevance: Mare serum and colostrum IgA concentrations may be useful peripartum predictors of neonatal mucosal immune status, enabling earlier intervention to prevent the consequences of mucosal infections.

Reasons for performing study: Transvaginal ultrasound-guided follicle aspiration (TVA) is performed clinically but there is little information available on complications associated with this procedure.

Objectives: It is possible that TVA is associated with damage to the ovary and may induce peritonitis or peritoneal adhesions. This study was conducted to determine the effect of repeated TVA on mare health and ovarian status.

Methods: Thirty-two mares were used for oocyte recovery via repeated TVA over a 3 year period; different mares were used each year. In Year 1, ovarian status was monitored in 11 mares by transrectal palpation and ultrasonography. In Year 2, 6 of 11 mares underwent abdominocentesis and were examined by laparoscopy after one TVA and again after multiple TVAs. In Year 3, 10 mares underwent multiple TVAs with either a 15 or a 12 gauge needle and the ovaries were removed for examination.

Results: Four hundred and twenty-seven aspiration sessions (390 via TVA and 37 via needle placement through the flank) and 3202 follicle punctures (3161 TVA and 41 flank) were performed. One mare developed an ovarian abscess. Transient rectal bleeding was evident after 16% of TVA sessions. No adhesions were found on laparoscopic or gross examination of ovaries and there were minimal changes on histological evaluation.

Conclusions: Follicle aspiration carries a small possibility (< 0.5%) of ovarian abscess formation. There is a possibility of rectal abrasion or puncture but little gross or histological damage to the ovary.

Potential relevance: These results provide a basis for using prophylactic administration of antibiotics after TVA and for advising mare owners of the rare but potential complications associated with the procedure.

Objectives: A wireless, inertial sensor-based system has previously been validated for evaluation of equine lameness. However, threshold values have not been determined for the assessment of responses to flexion tests. The aim of this investigation was to evaluate a sensor-based system for objective assessment of the response to flexion.

Methods: Healthy adult horses (n = 17) in work were recruited prospectively. Horses were instrumented with sensors on the head (accelerometer), pelvis (accelerometer) and right forelimb (gyroscope), before trotting in a straight line (minimum 25 strides) for 2 consecutive trials. Sensors measured 1) vertical pelvic movement asymmetry (PMA) for both right and left hindlimb strides and 2) average difference in maximum and minimum pelvic height (PDMax and PDMin) between right and left hindlimb strides in millimetres. A hindlimb was randomly selected for proximal flexion (60 s), after which the horse trotted a minimum of 10 strides. Response to flexion was blindly assessed as negative or positive by an experienced observer. Changes in PMA, PDMax and PDMin between baseline and flexion examinations were calculated for each test. Statistical analysis consisted of a Pearson's product moment test and linear regression on baseline trials, Mann-Whitney rank sum test for effect of flexion and receiver operator curve (ROC) analysis of test parameters.

Results: There was a strong correlation between trials for PMA, PDMin and PDMax measurements (P < 0.001). A positive flexion test resulted in a significant increase in PMA (P = 0.021) and PDMax (P = 0.05) only. Receiver-operator curve analysis established cut-off values for change in PMA and PDMax of 0.068 and 4.47 mm, respectively (sensitivity = 0.71, specificity = 0.65) to indicate a positive response to flexion.

Conclusions: A positive response to flexion resulted in significant changes to objective measurements of pelvic symmetry.

Potential relevance: Findings support the use of inertial sensor systems to objectively assess response to flexion tests. Further investigation is warranted to establish cut-off values for objective assessment of other diagnostic procedures.

Reasons for performing study: The stability of total CO2 concentration (ctCO2) in plasma is influenced by storage temperature and handling during sample processing. Conflicting information exists regarding the stability of ctCO2 in equine plasma over time, and the effect of centrifugation on the measured value for plasma ctCO2 is unclear.

Objectives: To determine plasma ctCO2 stability over 5 days when equine blood is collected into Vacutainer tubes, centrifuged within 30 min of collection, and stored at 4 degrees C; and to determine whether a delay in centrifugation increases the rate at which plasma ctCO2 decreases over time.

Methods: Blood was collected from 6 adult horses into 3 ml plastic Vacutainer tubes and randomly assigned to be centrifuged immediately, or after, storage. Plasma ctCO2 was measured in triplicate at 0, 24, 48, 72 and 96 h after collection using a NOVA-4 analyser Data were analysed using multivariable linear regression, with P < 0.05 being defined as significant.

Results: Plasma ctCO2 decreased linearly over time during storage at 4 degrees C. The measured value for ctCO2 decreased at a faster rate (-0.28 mmol/l/day; P < 0.0001) when centrifugation was delayed, compared with immediate centrifugation (-0.10 mmol/l/day). There was a significant effect of sequence of sample analysis on the ctCO2 value when measured in triplicate: the second and third measurements were 0.31 and 0.41 mmol/l lower than the first measurement, respectively.

Conclusions: Blood samples collected from horses into Vacutainer tubes should be centrifuged immediately after collection and analysed as soon as possible to ensure accurate values for plasma ctCO2.

Potential relevance: Failure to centrifuge, or excessive delay in measuring ctCO2 after centrifugation, produces values significantly lower than the true value.

Reasons for performing study: Early, accurate diagnosis of ascending placentitis in mares remains a key challenge for successful treatment of the disease. Doppler ultrasonography has shown promise as a tool to diagnose pregnancy abnormalities and is becoming more available to equine clinicians. However, to date, no studies have prospectively compared this technique to standard B-mode measurement of the combined thickness of the uterus and placenta (CTUP).

Objectives: The objective of the current study was to compare Doppler and B-mode ultrasonography for the detection of experimentally-induced ascending placentitis in mares.

Methods: Eleven healthy pony mares in late gestation were used in this study. Placentitis was induced in 6 mares between Days 280 and 295, while 5 mares served as negative controls. All mares were intensively monitored until delivery. Fetal heart rate, CTUP, uterine artery blood flow (resistance index, pulsatility index, arterial diameter and total arterial blood flow) and physical examination findings were recorded at each examination. Mares with an increased CTUP above published values were treated in accordance with published recommendations. Foals and fetal membranes were examined at birth. Ultrasonographic parameters were compared between groups using ANOVA. Foal viability and histological presence of placentitis were compared using a Fisher's exact test.

Results: The CTUP was increased above normal in 5 of 6 inoculated mares within 3 days after inoculation (P = 0.05). The sixth inoculated mare was excluded from subsequent data analysis. Uterine artery blood flow, physical examination findings and fetal heart rate were not different between groups. Gradual increases in CTUP, arterial diameter and total arterial blood flow were detected with increasing gestational age in the control mares (P = 0.02, P = 0.00001 and P = 0.00001, respectively).

Conclusion: The CTUP, but not uterine blood flow, was different between groups (P = 0.00001). Recorded CTUP values for control pony mares were similar to previously published values for light breed horses.