Phylogenetic relationships of German heavy draught horse breeds inferred from mitochondrial DNA D-loop variation

Summary We analysed a 610-bp mitochondrial (mt)DNA D-loop fragment in a sample of German draught horse breeds and compared the polymorphic sites with sequences from Arabian, Hanoverian, Exmoor, Icelandic, Sorraia and Przewalski's Horses as well as with Suffolk, Shire and Belgian horses. In a total of 65 horses, 70 polymorphic sites representing 47 haplotypes were observed. The average percentage of polymorphic sites was 11.5% for the mtDNA fragment analysed. In the nine different draught horse breeds including South German, Mecklenburg, Saxon Thuringa coldblood, Rhenisch German, Schleswig Draught Horse, Black Forest Horse, Shire, Suffolk and Belgian, 61 polymorphic sites and 24 haplotypes were found. The phylogenetic analysis failed to show monophyletic groups for the draught horses. The analysis indicated that the draught horse populations investigated consist of diverse genetic groups with respect to their maternal lineage.     

Ruptured capsule of the elbow joint of a draught horse

A cyst filled with fluid was found to be the cause of an enlarged antebrachium in a horse. Communication between the cyst and the elbow joint was demonstrated by: 1) finding, during radiographic examination of the elbow, radiopaque contrast solution instilled into elbow joint within the cyst; 2) finding cytological values in fluid aspirated from the cyst that were similar to those in fluid aspirated from the elbow joint; and 3) finding hyperechoic foci, assumed to be air bubbles, during ultrasonographic examination of the cyst after administration of air into the elbow joint. Communication of the cyst with the elbow joint was confirmed during post mortem examination of the affected limb.     

Pedigree analysis in the Austrian Noriker draught horse: genetic diversity and the impact of breeding for coat colour on population structure

The pedigree of the current Austrian Noriker draught horse population comprising 2808 horses was traced back to the animals considered as founders of this breed. In total, the number of founders was 1991, the maximum pedigree length was 31 generations, with an average of 12.3 complete generations. Population structure in this autochthonous Austrian draught horse breed is defined by seven breeding regions (Carinthia, Lower Austria, Salzburg, Styria, Tyrol, Upper Austria and Vorarlberg) or through six coat colour groups (Bay, Black, Chestnut, Roan, Leopard, Tobiano). Average inbreeding coefficients within the breeding regions ranged from 4.5% to 5.5%; for the colour groups, the coefficients varied from 3.5% to 5.9%. Other measures of genetic variability like the effective number of founders, ancestors and founder genomes revealed a slightly different genetic background of the subpopulations. Average coancestries between and within breeding areas showed that the Salzburg population may be considered as the nucleus or original stock whereas all other subpopulations showed high relationship to horses from Salzburg. The target of draught horse breeding in the 21st century does not meet the breeding concept of maximizing genetic gains any more. Stabilizing selection takes place. In this study, we show that demographic factors as well as structure given by different coat colours helped to maintain genetic diversity in this endangered horse breed.     

Morphological analysis and effect of selection for conformation in the Noriker draught horse population

To evaluate the breeding program in the Austrian Noriker draught horse population, which is mostly based on conformation, 31 body measurements from 497 horses in seven breeding areas of Austria were recorded. In addition, the data of 2376 horses (the current breeding population) from the studbook, containing 10 scored conformation traits and 4 body measurements per individual, were analysed. We assumed breeding regions, coat colour strains and breeding classes assigned according to conformation evaluation to be the main factors in phenotypic diversity of this Austrian draught horse breed. Significant differences and distances were found for all of these factors. Whereas differences between breeding areas mostly are due to housing conditions and feeding strategies, the breeding classes provide a very distinct picture of the current trends in Noriker breeding. Breeding organisations favour a long and high Noriker draught horse, a tendency that is the same for all departments. Heritability estimates for morphological traits vary from 0 to 0.67, and from 0.08 to 0.37 for linear type traits.     

Closed reduction of scapulohumeral joint luxation in an Icelandic horse after general anaesthesia

This report describes the clinical, ultrasonographic and radiographic findings in an 8‐year‐old Icelandic mare with unilateral shoulder luxation after general anaesthesia. Reduction of the luxated humerus was performed in a closed fashion using a calving jack under general anaesthesia. The horse recovered well and ultimately returned to its previous level of performance.     

Successful cardiopulmonary resuscitation in an adult horse following cardiovascular collapse on recovery from general anaesthesia in the Trendelenburg position

Equine anaesthesia is associated with a high risk of perioperative morbidity and mortality, particularly in the recovery period. Cardiovascular collapse and cardiopulmonary arrest (CPA) have been reported to account for one-third of anaesthesia-related perioperative deaths in the horse. This case report describes the successful cardiopulmonary resuscitation of a healthy adult Thoroughbred mare that developed cardiovascular collapse and subsequent CPA following positioning in the recovery box after general anaesthesia in the Trendelenburg position. Cardiopulmonary resuscitation (CPR) was instigated and included thoracic compressions, intermittent positive pressure ventilation and adrenaline administered via the intravenous and intra-tracheal routes. Return of spontaneous circulation (ROSC) was detected 5 min and 50 s after the start of CPR. A stable stance was achieved approximately 100 min after ROSC. The mare was discharged from the hospital 3 days later with no known complications. To the authors’ knowledge, this is the first case report documenting CPA following general anaesthesia in the Trendelenburg position in a horse, with subsequent successful CPR. The precise cause of the CPA is unknown but a number of plausible hypothesis are discussed including hypoventilation and a Bezold-Jarisch reflex.     

Computed tomographic (CT) arthrogram contributes to the diagnosis of an osteochondroma of the distal calcaneus in a horse

Osteochondromas in the horse are most commonly found as a solitary lesion affecting the distal radial metaphysis. In this location, diagnosis is reliant on radiographic and ultrasonographic examination and confirmed with post-operative histopathology. This case report describes the additional benefit of performing a CT arthrogram to aid the diagnosis of an osteochondroma in an atypical location.     

Osteosarcoma of the middle phalanx in a horse

An 11‐year‐old Thoroughbred gelding was presented for lameness investigation following acute onset hindlimb lameness, which developed during a period of paddock turnout. Clinical examination revealed a swelling over the dorsolateral aspect of the pastern that was painful on digital palpation. Radiography of this area was consistent with an aggressive bone lesion involving both joint surfaces of the middle phalanx with pathological fracture and distal collapse of this bone. On this basis, the horse was subjected to euthanasia. Post mortem histopathological examination revealed presence of an osteosarcoma without involvement of the articular cartilage. This bone tumour is extremely rare in horses and has not been reported in this anatomical location.     

The treatment of diarrhoea in the adult horse

The priority in treating the equine patient with acute diarrhoea is to stabilise the haemodynamic aberrations secondary to the fluid and electrolyte losses. Once this has been initiated and the patient is stabilised ancillary treatments may be beneficial. Besides the well established effects of NSAIDs and polymixin B on systemic inflammation, recent studies suggest that the use of DTOS to bind bacterial toxins and Saccharomyces boulardii to reduce the severity and duration of diarrhoea may be beneficial. The justification for using probiotic products is scant. There is no evidence to suggest that systemic use of antimicrobials benefits equine patients with colitis, with the exception of metronidazole in cases of clostridial diarrhoea. In light of their potentially detrimental effects, their use can, in the opinion of the authors, not be advocated. Better understanding of the pathways of systemic inflammation and more selective anti‐inflammatory drugs may be of great benefit in the future.     

Detection of clade 2 equine influenza virus in an adult horse recently imported to the USA

A 4‐year‐old Warmblood mare presented to the William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California at Davis with bilateral mucoid nasal discharge and pyrexia. The mare had recently been imported from Germany, arriving at a quarantine holding facility 72 h prior to presentation. Based on clinical presentation and culture results of tracheal fluid, the mare was diagnosed with bacterial bronchopneumonia secondary to equine influenza. The equine influenza virus (EIV) identified in the imported mare displayed 99.1% nucleotide homology of the HA1 gene to the prototype Florida sublineage clade 2 isolate A/equine/Richmond/1/2007 (H3N8). This case illustrates the risk of introducing a clade 2 EIV in North America.     

Treatment of a metallic foreign body in the cranial cervical region of a horse

Ingestion of foreign bodies is uncommon in horses when compared with indiscriminate grazers such as cattle. This case report describes the diagnosis and treatment of a cervical abscess in a Thoroughbred racehorse thought to be associated with ingestion of wire. Radiographic and ultrasonographic examination provided a diagnosis, and conservative treatment of the lesion with antimicrobials initially allowed the lesion to localise closer to the skin for safer surgical exploration. Intra-operative ultrasonographic imaging facilitated surgical access, removal of the foreign body, and drainage. While surgical treatment is usually necessary to resolve an abscess, initially conservative therapy may help to improve the prognosis by simplifying surgical access and reducing the risk of surgical complications.     

Comparison of four techniques of arthrocentesis of the lateral compartment of the femorotibial joint of the horse

Reasons for performing study: Clinical experiences indicate that centesis of the lateral compartment of the femorotibial joint is often unsuccessful. Objective: To determine the accuracy of 2 published and 2 unpublished techniques of centesis of the lateral compartment of the femorotibial joint. Hypothesis: It was hypothesised that a drug can be administered into the lateral compartment of the femorotibial joint via a diverticulum of this joint that surrounds the medial aspect of the long digital extensor tendon and that this technique is more accurate than described techniques of centesis of this compartment. Methods: Twenty‐four stifles of 12 horses were divided equally into 4 groups and a radiocontrast medium injected into the lateral compartment of the femorotibial joint of each group using a hypodermic needle inserted: 1) caudal to the lateral patellar ligament and proximal to the tibial plateau, 2) caudal to the long digital extensor tendon and proximal to the tibial plateau, 3) between the long digital extensor tendon and bone of the extensor groove of the tibia or 4) directly through the long digital extensor tendon until it contacted bone. Twelve veterinary students who had no experience using any of these techniques performed the injections. Accuracy of each technique was determined by examining radiographs obtained after injecting the contrast medium. Results: The most successful technique for arthrocentesis was by inserting a needle through the long digital extensor tendon. This approach was successful in all attempted cases, whilst other techniques had lower rates of success. Conclusions: The lateral compartment of the femorotibial joint can be accessed accurately by inserting a needle through the long digital extensor tendon as it lies within the extensor groove. Other techniques may not be as accurate for clinicians inexperienced in arthrocentesis of the lateral compartment of the femorotibial joint.     

Surgical resection of an osteoma of two thoracic spinous processes in a horse

This report describes the successful surgical removal of an osteoma of the thoracic dorsal spinous processes of a horse that presented with back pain. Osteomas of the spine are frequently reported in the literature in people, but have not been previously described in the horse.     

Transrectal ultrasonographic examination of the sacroiliac joints of the horse: Abnormal findings and lesions

Transrectal ultrasonography is a useful technique for the assessment of sacroiliac osteoarthrosis because of the ventral localisation of lesions. Comparison between the right and left side is essential. Due to the deep localisation of the sacroiliac joints, other imaging modalities have limitations for diagnosing osteoarthrosis. A grading system from 1 to 4 is suggested in order to classify the severity of lesions based on the shape of the articular margins and architecture of the ventral sacroiliac ligament. Abnormal ultrasonographic findings should be correlated with clinical manifestations.     

Radiographic retrospective study of the caudal cervical articular process joints in the horse

Reasons for performing study: Arthropathy of the caudal cervical articular process joints (APJs) in the horse is documented as a cause of ataxia and paresis secondary to spinal cord compression. Enlargement of the caudal APJs is reported to increase with age, but there are no known associations of any other factors. No association of the degree of APJ enlargement with neurological signs seen has been documented. This study investigated the associations of cervical APJ enlargement at the C5‐C6 and C6‐C7 articulations with case subject details (breed, age, sex, usage) and clinical signs. Objectives: To ascertain if there are of any associations between: the subject details and enlargement of the caudal cervical APJs; and the degree of APJ enlargement and the presence and type of clinical signs. Hypotheses: There would be an effect of age, breed and usage on APJ grade, with no effect of sex. Association between grade and clinical signs seen was also investigated. Materials and methods: The radiographs of 122 horses qualified for inclusion. Horses were excluded if they were known to have a neck lesion cranial to C5‐C6, or if the radiographs were rotated or of poor quality. In order to standardise the interpretation of APJ enlargement, a novel grading system was developed and used. Results: An association was found between age and APJ grade at C5‐C6 but not C6‐C7. There was no association between grade, breed, sex and usage, or clinical signs seen. Data also showed a trend for increasing enlargement the more caudal the APJ. Conclusion and potential relevance: The data in this study support that the size of the caudal cervical APJ at the level of C5‐C6, appear to increase with age, but this enlargement may not be significant. Enlargement cannot be associated with breed, sex or discipline of the horse at present, and specific grades and therefore degree of enlargement, cannot necessarily be assumed to be the cause of neurological deficits.     

Transrectal ultrasonographic examination of the sacroiliac joints of the horse: Technique and normal images

Transrectal ultrasonography of the sacroiliac joints is routinely performed for the diagnosis of the cause of low back pain and lack of power in the hindlimbs. As a result of the localisation of these small joints, performing and interpreting ultrasonographic images requires a good anatomical knowledge. This paper describes an ultrasonographic procedure that allows imaging of the ventral aspect of the sacroiliac joints. A complete screening should be done to evaluate the articular margins. Moreover, the shape of sacral and iliac wings can vary among individuals especially depending on the gender.     

Primary ossifying fibroma of the proximal phalanx in a horse

A primary ossifying fibroma was found at necropsy in a 5-year-old Welsh pony cross mare that was humanely subjected to euthanasia for an intractable severe left hindlimb lameness. Antemortem radiographs of the left hind pastern were characterised by articular, subchondral and cortical areas of lysis. Primary ossifying fibroma is a rare lesion of the distal limb but should be considered when there is extensive lysis extending into the medulla and proximal cortical bone.