Weight reduction and possible implications for the rehabilitation of horses with ambulatory difficulties

Equine musculoskeletal injuries, or other causes of reduced movement, can have a poor prognosis partially due to the secondary complications that may develop during recovery or rehabilitation. These can include supporting limb laminitis due to excessive weightbearing on healthy limbs and also problems associated with ventilation or perfusion due to prolonged recumbency. The risk of these complications is reported to increase with increasing body weight. While many methods have been attempted to reduce load and prevent complications, there is no current standard practice when managing horses with ambulatory difficulties. One critical consideration with load reduction devices is maintaining sufficient mobility to allow for blood flow and the prevention of muscle wasting. One of the most challenging obstacles with any weight reduction method or device is preventing pressure sores/ulcers or other tissue trauma because load is redistributed away from the limbs and onto regions of the body unaccustomed to weightbearing. Reported methods to aid in recovery and rehabilitation include rescue slings, forced recumbency, flotation tanks, water treadmills and aquatic therapy. While these methods have been successful in some horses, significant complications have also been reported. If too much weight is removed, muscle wasting or osteopenia occurs; conversely, if insufficient weight is lifted blood flow is hindered. The optimal load reduction is not known because each individual horse will have different requirements depending on the severity of the injury. The goal would be to restore normal weight distribution on the noninjured limbs, while supporting the weight that would normally be placed on the injured limb.     

The relationship between cheek tooth occlusal morphology, apparent digestibility, and ingesta particle size reduction in horses

OBJECTIVE: To investigate potential relationships between cheek tooth occlusal morphology, apparent feed digestibility, and the reduction in feed particle size that occurs during digestion in horses. DESIGN: Cross-sectional study. ANIMALS: 17 horses of various ages and breeds and either sex. PROCEDURES: Horses were fed 1 of 3 hay-based diets ad libitum for 14 days prior to euthanasia; nutrient analysis was performed on samples of each of the 3 diets. At the time of postmortem examination, the head was disarticulated, photographs were taken of the occlusal surfaces of the maxillary and mandibular cheek tooth arcades, and samples of stomach and small colon or rectum contents were collected for determination of apparent feed digestibility and particle size determination. An overall oral pathology score was assigned, and morphologic features of the occlusal surfaces of the cheek tooth arcades were determined. RESULTS: Results of nutrient analyses did not differ among the 3 hay diets, and there was no significant difference in apparent feed digestibility among diets. Feed particle size differed significantly among the 3 diets, but stomach content and fecal particle sizes did not differ among diet groups. No significant correlations were identified between cheek tooth morphologic variables and feed digestibility, and fecal particle size was not significantly associated with oral pathology score. CONCLUSIONS AND CLINICAL RELEVANCE: Results did not provide any evidence of associations between cheek tooth morphologic variables, fecal particle size, and apparent digestibility in horses.     

Association analysis of novel polymorphisms in 2′, 5′‐oligoadenylate synthetase gene with reproductive traits in indigenous and cross‐bred cattle of Indian Origin

2′, 5′‐Oligoadenylate synthetases (OAS) are important components of an interferon‐mediated antiviral pathway. No polymorphisms in exonic regions of bovine OAS1 gene have been identified and associated with reproduction traits. The objective of the study was to detect and evaluate the effects of mutations in exonic region of bovine OAS1 gene with reproduction traits in cattle. DNA samples collected from 250 individual cows of two Indian dairy breeds (Sahiwal and Frieswal) of cattle were used in the study. The genetic variants of the OAS1 gene were identified with polymerase chain reaction–single‐strand conformation polymorphism (PCR‐SSCP) and sequence analysis using seven set of primer pairs. The PCR‐SSCP analysis revealed polymorphism in the fragments comprising of exon 2, exon 5 and first fragment of exon 6 while the fragments of exons 1, 3, 4 and second fragment of exon 6 were monomorphic in Sahiwal and Frieswal cattle. The mutations in the amplified region comprising of exon 2 were found to have significant association with age at first breeding and calving, service period, dry period and pregnancy rate. Significant associations were found between SNPs in the exon 5 and service and dry periods of the animal, whereas the genetic variants in the first fragment of the exon 6 showed significant association with age at first breeding and calving. To our knowledge, this study demonstrated for the first time that the polymorphisms in OAS1 gene were associated with reproductive traits and it can be chosen as a candidate gene for improvement of reproductive performance of cattle.     

Effect of dental floating on the rostrocaudal mobility of the mandible of horses

OBJECTIVE: To evaluate the effect of dental floating on the position of the mandible relative to the maxilla (a measure of rostrocaudal mobility [RCM] of the mandible) during extension and flexion of the head of horses. DESIGN: Randomized controlled blinded trial. ANIMALS: 59 horses housed in 1 barn. PROCEDURE: Horses were formally randomized into a treatment (n = 33) or control (26) group. All horses were sedated, and the distance between rostral portions of the upper and lower incisor arcades were determined with the head fully extended and flexed at the poll (the difference in measurements represented the RCM of the mandible). The oral cavity was examined. For the treatment group, dental floating was performed, and the incisor arcade measurements were repeated. RESULTS: Dental correction resulted in a significant increase in RCM of the mandible in 31 of 33 horses. The mobility was greater in heavy horses than that detected in other breed classifications. Age and number of dental lesions did not significantly affect mobility before or after dental floating. CONCLUSIONS AND CLINICAL RELEVANCE: Dental floating increased RCM of the mandible, but measurement of this variable was not an indicator of the number or extent of dental lesions, and no specific dental abnormality appeared to significantly affect RCM of the mandible in horses. In horses, measurement of RCM of the mandible can be used as a guide to determine whether dental correction is necessary; after dental floating, it can be used to ensure that irregularities of the occlusal surface have been corrected.     

Effect of rostrocaudal mobility of the mandible on feed digestibility and fecal particle size in horses

OBJECTIVE: To evaluate the effect of rostrocaudal mobility (RCM) of the mandible during extension and flexion of the atlanto-occipital joint on weight gain, feed digestibility, and fecal particle size in horses. DESIGN: Randomized controlled trial. ANIMALS: 34 pregnant mares housed in 1 barn. PROCEDURES: Horses were randomized into a treatment (n = 17) or control (17) group. All horses were sedated, and the distance between the rostral portions of the upper and lower incisor arcades was determined during extension and flexion of the atlanto-occipital joint; mandibular RCM was calculated as the difference between these values. In the treatment group, measurements were made after dental floating. Body weight was recorded 1 day before dental floating and at intervals after mandibular RCM determination for a period of 24 weeks. Feces were collected from each horse during two 5-day periods. Samples of feed and feces were analyzed to determine feed digestibility; particle size analysis was performed on dried fecal samples. RESULTS: Data obtained from each group of horses revealed that RCM of the mandible did not affect weight gain, feed digestibility, or particle size in feces; there were no differences among breeds. Controlling for age and number of dental lesions did not significantly affect results. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, RCM of the mandible did not appear to affect weight gain, feed digestibility, or fecal particle size. On the basis of these and other published data, the assumption that dental abnormalities affect digestion detrimentally in horses needs to be reevaluated.     

Intraoperative depression of the bulla of the maxillary septum as a method of improving sinus drainage without epistaxis in horses

Current methods of creating sinus drainage and allowing egress of a sinus pack at the end of surgery create significant haemorrhage. Given that haemorrhage is already a concern in some sinus surgeries, the method described allows for a significant reduction in blood loss. The objective was to describe a method of enlarging the nasomaxillary aperture in horses to allow egress of a sinus pack, and subsequent endonasal treatment, without incurring significant haemorrhage. The bulla of the maxillary septum is depressed using a gloved finger (through a sinus flap or trephine hole) or using a long curved Peine instrument under sinoscopic control before fenestration. No major operative or post-operative complications have been encountered. Satisfactory widening of the nasomaxillary aperture has been accomplished in all cases, although at times, when the bulla is under the floor of the dorsal conchal sinus, it can be difficult to compress. It is imperative that this procedure be performed before fenestration. If performed after fenestration, the most rostral edge of the fenestration can be difficult to identify, and this becomes an impediment to widening the nasomaxillary aperture. Enlarging the nasomaxillary aperture with a finger or blunt instrument allows improvements in sinus drainage without the complication of severe epistaxis. Depression of the bulla of the maxillary septum, before surgical fenestration into the rostral maxillary and ventral conchal sinuses, allows opening of the nasomaxillary aperture with minimal haemorrhage. Thereafter, the sinus pack can be egressed via this route, which is also large enough to perform sinus lavage and post-operative treatments endonasally without the risk of disturbing the external surgical site.