A microbiome analysis of equine peripheral dental caries using next generation sequencing

BACKGROUND

Although, peripheral caries (PC) affects almost half of UK horses, no comprehensive microbiological study has been performed on this disorder. As a high proportion of oral bacteria cannot be conventionally cultured, molecular microbiological techniques such as Next Generation Sequencing are required to examine the complex oral bacteria community.

OBJECTIVES

To identify the microbiota involved in equine PC, including comparing microbiota at the more commonly and severely affected three caudal cheek teeth with the less commonly affected three rostral cheek teeth.

STUDY DESIGN AND METHODS

Equine dental plaque samples were collected from the palatal aspects of cheek teeth of 63 horses. DNA was isolated and amplified using PCR, targeting the V4 region of the 16S rRNA gene and Next Generation Sequencing of these gene amplicons was performed. The acquired data were processed and analysed using Mothur and R.

RESULTS

Streptococcus species was the genus most commonly associated with equine PC, whereas Gemella species was the genus most associated with the control group. In a further analysis where the rostral and caudal cheek teeth were compared with each other and with the control group. Veillonella species was the most commonly associated genus with PC of the rostral cheek teeth, Streptococcus species was the most associated genus with the caudal cheek teeth, and Corynebacterium with the control group.

MAIN LIMITATIONS

Some bacteria can have multiple heterogeneous copies of the 16S rRNA gene, which can affect the estimation of their relative abundance.

CONCLUSIONS

Similar to caries studies in other species, acidogenic and aciduric microorganisms including Streptococcus species were found to be associated with equine peripheral caries.

Heritability and prevalence of selected osteochondrosis lesions in yearling Thoroughbred horses

BACKGROUND

Osteochondrosis is considered multifactorial in origin, with factors such as nutrition, conformation, body size, trauma and genetics thought to contribute to its pathogenesis. Few studies have investigated the effects of genetic variability of osteochondrosis in Thoroughbreds.

OBJECTIVES

To describe the prevalence and genetic variability of a subset of osteochondrosis lesions in a group of Thoroughbred yearlings.

STUDY DESIGN

Retrospective cohort study.

METHODS

Radiographs of 1962 Thoroughbred yearlings were retrieved from clinical records obtained between 2005 and 2013. Pedigree information was obtained from the Australian Stud Book. Osteochondrosis lesions were documented in selected joints and estimates of heritability were obtained by fitting linear mixed models in ASREML software.

RESULTS

The overall prevalence of osteochondrosis was 23%. Osteochondrosis was identified in 10% of stifle joints, 6% of hock joints and 8% of fetlock joints. The heritability estimates ranged from 0 to 0.21. The largest estimates were 0.10, 0.14, 0.16 and 0.21 for lesions of the distal intermediate ridge of the tibia, dorso-proximal proximal phalanx (P1), any stifle osteochondrosis, and lesions of the lateral trochlear ridge of the distal femur, respectively. Although calculated heritability estimates had high standard errors, meta-analyses combining the present results with published estimates were significant at 0.10, 0.17, 0.15 and 0.20 for stifle, tarsal, fetlock and these joints combined, respectively. In addition, there was a permanent environment attributable to the dam effect.

MAIN LIMITATIONS

Inclusion criteria were based on radiographic findings in specific joints at a specific age range in Thoroughbreds.

CONCLUSIONS

The present results indicate that only a proportion of osteochondrosis in Thoroughbreds is heritable. The permanent environment effects of the dam were observed to have effects on some categories of osteochondrosis.

Orthodontic correction of overjet/overbite ('parrot mouth') in 73 foals (1999-2013)

REASONS FOR PERFORMING STUDY

There are limited reports on the efficacy of functional orthodontic correction of overjet or overbite in foals.

OBJECTIVES

To report the outcome of using orthodontic tension bands in combination with an inclined plane biteplate in the treatment of overjet, with or without concurrent overbite, rates of correction of these 2 malocclusions and associated complications. And to examine factors associated with outcomes.

STUDY DESIGN

Retrospective case series.

METHODS

Clinical records for 73 foals treated at a single clinic, by the same surgeon were analysed. Overall change and rates of change in overjet and overbite were calculated. Associations between potential explanatory variables including age, severity of initial malocclusion and surgeon experience were examined using linear regression.

RESULTS

Records for 73 foals (43 colts, 30 fillies) were evaluated. The median number of implant placements per animal was 2 (range 1-4). Of 61 cases with complete records, reduction in overjet and overbite dimensions were achieved in 95% and 90% of foals, respectively, with mean reductions in malocclusions of 9.9 and 8.4 mm, respectively. Complete reduction in overjet was achieved in 25% (15/61) and reduction of malocclusion dimensions to ≤5 mm (i.e. functionally corrected) was achieved in 51% (31/61). Increasing animal age was significantly associated with decreased total reduction in overjet and decreased rate of reduction in overbite. Increased original severity of overbite was significantly associated with increased rate of its correction. Short-term complications included intraoperative haemorrhage, transient facial nerve neuropraxia and irritation of the mare's udder by the brace. Longer-term complications included cheek teeth diastema formation and incisor discoloration and maleruption.

CONCLUSIONS

Using this technique, correction or improvement of these malocclusions is rapid, with minimal complications. Often more than one implant is required. Animal age at the start of treatment is associated with rate and amount of correction achievable, so initiating treatment at an early age is recommended.

Anatomical and histological study of the dorsal and ventral nasal conchal bullae in normal horses

The morphology of the dorsal conchal bulla (DCB) and ventral conchal bulla (VCB) are poorly described. The recent recognition that these bullae can become infected, causing chronic unilateral nasal discharge, has stimulated interest in these structures. Fourteen cadaveric horse heads were transected sagittally midline and dissected to expose the nasal conchal bullae. The dimensions of each bulla, the number and orientation of drainage apertures, and cellulae septae were recorded. Randomly selected samples were examined histologically. The mean DCB and VCB lengths were 78  and 57 mm, respectively; equivalent to 13.9 per cent and 10.2 per cent of skull length, respectively. The mean DCB and VCB heights were 29  and 28 mm, respectively; equivalent to 5.2 per cent and 5 per cent of skull length, respectively. The DCB was larger than the VCB, containing more septae, cellulae and drainage apertures. No communications were identified between the bullae and the immediately adjacent paranasal sinuses. Histology revealed that the bullae consist of ciliated, pseudostratified, columnar epithelium over glandular submucosa often overlying turbinate bone and, variably, hyaline cartilage. This more detailed description of equine DCB and VCB anatomy will hopefully facilitate successful treatment of their disorders.

Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015

REASONS FOR PERFORMING STUDY

The morphology of the dorsal (DCB) and ventral (VCB) nasal conchal bullae, including their cellulae, drainage and histology, are poorly described. The recent recognition that these bullae can become infected, causing chronic unilateral nasal discharge has stimulated interest in these structures. A more complete understanding of their anatomy would be useful in the diagnosis and treatment of their disorders.

OBJECTIVES

To document the structure, drainage and histology of the equine DCB and VCB.

STUDY DESIGN

Descriptive.

METHODS

Fourteen fresh cadaveric horse heads, were transected sagittally midline and dissected to expose the nasal conchal bullae. The dimensions of each bulla, the number of drainage apertures, the number of cellulae and orientation of the septae were recorded. Representative samples were collected for histopathology.

RESULTS

The mean lengths of the DCB and VCB were 77.7 mm (range 48-105 mm) and 57.1 mm (range 34-86 mm) respectively; equivalent to 13.8% and 10.2% of skull length, respectively. The mean widths of the DCB and VCB were 28.5 mm (range 21-35 mm) and 28.2 mm (range 13-41 mm) respectively; equivalent to 5.1% and 5% of skull length respectively. The median number of drainage apertures from the DCB and VCB were 2 and 1 respectively. The median number of cellulae within the DCB and VCB were 3 and 2, respectively. No communications were identified between the DCB and VCB and the adjacent paranasal sinuses. Histology revealed that the bullae consisted of ciliated, pseudostratified, columnar epithelium supported by a glandular submucosa often overlying turbinate bone and, variably, hyaline cartilage.

CONCLUSIONS

The morphology of the equine nasal conchal bullae is quite variable. The DCB is generally a more complex structure than the VCB, containing more septae, cellulae and drainage apertures. This more detailed description of DCB and VCB anatomy will hopefully facilitate successful treatment of their disorders. Ethical animal research: Research ethics committee oversight not currently required by this conference: the study was performed on material obtained from an abattoir.

SOURCE OF FUNDING

None. Competing interests: None declared.

Empyema of the nasal conchal bulla as a cause of chronic unilateral nasal discharge in the horse: 10 cases (2013-2014)

REASONS FOR PERFORMING STUDY

Empyema of the nasal conchal bullae has recently been identified in horses suffering from chronic unilateral nasal discharge. The diagnosis and management of such cases has not been reported previously.

OBJECTIVES

To describe the diagnosis and treatment of cases suffering from empyema of the nasal conchal bullae and report the frequency of diagnosis from a population of horses referred for head computed tomography (CT).

STUDY DESIGN

Retrospective case review.

METHODS

Records from cases diagnosed with nasal conchal bulla disease using CT were reviewed.

RESULTS

Abnormalities of the nasal conchal bullae were identified by CT in 10 cases (8 ventral conchal bulla, 2 dorsal conchal bulla), from 102 equine head CT examinations. Eight cases were subsequently treated at the study clinic, 7 of which had concurrent paranasal sinus disease. In 3 cases, fenestration of the ventral conchal bulla per nasum facilitated drainage and clearance of empyema.

CONCLUSIONS

Disease of the conchal bullae should be considered as a potential cause of chronic unilateral nasal discharge in horses. Clearance of empyema within these bullae is unlikely to occur through lavage of the paranasal sinuses alone. Where necessary, fenestration of the bulla allows physical removal of infected material.

Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion

Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, although anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facilitate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6 mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3 mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently, the majority of subsequent infundibular restorations are imperfect.

Deep digital flexor tendon injury within the hoof capsule; does lesion type or location predict prognosis?

The type and location of deep digital flexor tendon (DDFT) lesions may be important in predicting outcome. The objectives of this study were to determine the frequency of different types of DDFT lesions within the hoof capsule and to determine whether lesion type predicts return to athletic activity. Lesions of the DDFT were divided into: core lesions, dorsal border lesions and parasagittal splits. Lesion location was documented, and follow-up information was obtained by telephone survey at least 18 months after diagnosis. Of 168 horses with primary DDFT injury, 54 horses had dorsal border lesions, 59 had parasagittal splits and 55 had core lesions. Twenty-five per cent of all horses returned to previous levels of athletic activity within 18 months of MRI evaluation. Horses with complete splits or core lesions of the DDFT were significantly less likely to return to some level of athletic activity than horses with dorsal border lesions P<0.001. Dorsal border lesions of the DDFT appear to have a better prognosis than core lesions or parasagittal splits. This study provides additional information that may help clinicians predict the prognosis for different types of DDFT injury.

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in steeplechase starts in the United Kingdom (2001-2009)

The objective of this study was to identify risk factors for superficial digital flexor (SDF) tendinopathy in Thoroughbred horses in steeplechase races in the United Kingdom. Potential risk factors for SDF tendinopathy were studied between 1st January 2001 and 31st December 2009 using a cohort study design with 648 injuries sustained in 102,894 starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. In the final multivariable model, 12 statistically significant risk factors were identified. Variables that increased the odds of SDF tendinopathy included firmer going, increased horse age, and racing in the summer compared to other seasons. Variables that decreased the odds included having a higher official rating and the number of starts in the preceding days. Fewer and different risk factors were identified than in an equivalent model of SDF tendinopathy in hurdle racing, highlighting potential differences between these disciplines. Further collection of training and racecourse information would be beneficial and may help to explain further some of the associations identified in this study. The results will facilitate the development of strategies to improve overall safety of horses in UK steeplechase racing.