Some blood pressure studies in normal horses and in horses affected with chronic obstructive pulmonary disease

The literature indicated that the main obstacle to indirect peripheral blood pressure measurements (sphygmomanometry) in horses, is the lack of a large superficial artery capable of being temporarily occluded. Consequently, the standard human sphygmomanometric techniques employing palpatory and auscultatory methods are unsatisfactory in horses. Some other sphygmomanometric techniques including the xylol bead modified palpatory, the photoelectric and the modified auscultatory methods were assessed by trials on horses. The latter method was shown to be the only potentially useful technique.Blood pressure measurements using this technique showed that the blood pressure of resting horses shows continuous short term cyclic variations, an observation which was supported by direct peripheral blood pressure measurements. Peripheral blood pressure was shown to significantly increase in horses during excitement and also following submaximal exercise. During longer term studies, many technical difficulties were encountered with the modified auscultatory technique and it was concluded that it would be unlikely to become acceptable for general clinical use.The literature concerning right heart blood pressure measurements in horses indicated that very little information was available concerning the right heart blood pressure alterations that occur in chronic pulmonary disease. Angiographic studies indicated that the use of a single hydrostatic baseline for all right heart blood pressure as is currently used by all authors, causes estimation of right ventricular pressure. measurements, an under- A separate hydrostatic baseline was therefore established for right ventricular blood pressure measurements.It was shown that horses clinically affected with chronic obstructive pulmonary disease (COPD), had pulmonary and systolic right ventricular hypertension and that this hypertension became reversed during remission stages of the disease. Further studies showed that a close relationship existed between carotid arterial hypoxaemia and pulmonary hypertension in COPD affected horses.This relationship between arterial hypoxaemia and pulmonary hypertension in COPD was substantiated by inducing partial remission of pulmonary hypertension in clinically affected horses, by oxygen administration. In contrast, normal pulmonary hypertension was induced by rendering temporarily hypoxaemic, by administration of nitrogen enriched air.Marked pulmonary hypertension was also induced during experimental hypercapnia or acidosis production. Bicarbonate, atropine or furosemide administered intravenously had no significant short term effects on pulmonary arterial pressure. No clinical or cardiac catheterisation evidence of right heart failure was observed in any COPD affected horses. These observations were substantiated by the relative in frequency of right ventricular hypertrophy that was observed on post mortem examinations of horses affected with chronic pulmonary disease

Studies on Age-Related Changes in Equine Cheek Teeth Angulation and Dental Drift

BACKGROUND: Cheek teeth (second through fourth premolars and first through third molars) diastema is a common and painful equine disorder caused by the absence of effective tight interdental contact between these teeth. Limited objective information is available on the angulation of equine cheek teeth that control dental drift or on mesial or distal equine cheek teeth drift that should normally prevent this disorder. OBJECTIVES: To measure the angulation of the mesial and distal cheek teeth in horses of different ages, quantify age-related cheek teeth mesial and distal dental drift, and measure the cheek teeth row length in horses of different ages. STUDY DESIGN: Retrospective review of computed tomographic images of equine heads. METHODS: Case details and CT images from clinical equine cases that had undergone standing CT head examination were collated. Three sets of measurements were acquired from each head. “Head size” calculated as the distance between the caudal aspect of the orbit and the caudal aspect of the naso-incisive notch was used to standardize measurements in different sized heads. The length of the cheek teeth rows measured from the mesial aspect of the Triadan 06 occlusal surface to the distal aspect of the Triadan 11 occlusal surface. The rostro-caudal (antero-posterior) position and angulation of the mandibular and maxillary Triadan 06 and 11 teeth were measured in relation to reference lines drawn on CT images. RESULTS: Significant mesial drift occurred in the maxillary and mandibular Triadan 11s. Despite their distal angulation, the upper and lower Triadan 06s also drifted mesially. The mean angulation of Triadan 06 and 11 mandibular teeth (17.8 and 26.2°, respectively) was almost double that of maxillary teeth (9.2 and 13.3°, respectively) with both Triadan 11s having greater angulation than the 06s. Cheek teeth angulation only significantly decreased in the mandibular 06s. Cheek teeth arcade lengths decreased with age, but these decreases were not significant. MAIN LIMITATIONS: Limitations include the relatively small sample size. CONCLUSIONS: In the population of horses used for this study, age related mesial drift occurred in both Triadan 06 and 11s, and the angulation of these teeth did not decrease with age in most arcades

The microbiome associated with equine periodontitis and oral health

Equine periodontal disease is a common and painful condition and its severe form, periodontitis, can lead to tooth loss. Its aetiopathogenesis remains poorly understood despite recent increased awareness of this disorder amongst the veterinary profession. Bacteria have been found to be causative agents of the disease in other species, but current understanding of their role in equine periodontitis is extremely limited. The aim of this study was to use high-throughput sequencing to identify the microbiome associated with equine periodontitis and oral health. Subgingival plaque samples from 24 horses with periodontitis and gingival swabs from 24 orally healthy horses were collected. DNA was extracted from samples, the V3–V4 region of the bacterial 16S rRNA gene amplified by PCR and amplicons sequenced using Illumina MiSeq. Data processing was conducted using USEARCH and QIIME. Diversity analyses were performed with PAST v3.02. Linear discriminant analysis effect size (LEfSe) was used to determine differences between the groups. In total, 1308 OTUs were identified and classified into 356 genera or higher taxa. Microbial profiles at health differed significantly from periodontitis, both in their composition (p < 0.0001, F = 12.24; PERMANOVA) and in microbial diversity (p < 0.001; Mann–Whitney test). Samples from healthy horses were less diverse (1.78, SD 0.74; Shannon diversity index) and were dominated by the genera Gemella and Actinobacillus, while the periodontitis group samples showed higher diversity (3.16, SD 0.98) and were dominated by the genera Prevotella and Veillonella. It is concluded that the microbiomes associated with equine oral health and periodontitis are distinct, with the latter displaying greater microbial diversity