Sinusitis is a common disorder in horses and may result from trauma, dental diseases, or space-occupying lesions. Radiography can only provide a limited amount of information. Computed tomography (CT) has been documented as an alternative imaging method. Eighteen horses (mostly Warmblood) with signs of chronic sinusitis were examined preoperatively with CT to assist in diagnosis of the underlying cause. There was a group of common CT features in horses with dental disease and sinusitis. The first molar was the most frequently affected maxillary cheek tooth. Hypoattenuation of the cementum, destruction of the enamel, and filling of the infundibular cavity with gas were the most frequent CT findings associated with caries. Gas bubbles within the bulging root area or fragmentation of the root in combination with swelling of the adjacent sinus lining were the most important CT features of dental decay. CT findings associated with sinusitis included excessive thickening of the respiratory epithelium in the rostral maxillary sinus; the caudal maxillary sinus was less often involved. The infraorbital canal, the nasomaxillary duct, and the frontomaxillary aperture were usually involved. The maxillary bone, however, especially the facial crest, was involved in nearly every horse, being characterized by endosteal sclerosis, thickening, periosteal reaction, and deformation leading to facial swelling in chronic infections. CT images allowed identification of involvement of individual teeth more clearly to reveal the diseased one for treatment. Three-dimensional imaging allowed improved understanding of the extent and severity of the pathologic change.
Summary
Reasons for performing study: Equine melanomas occur most commonly in grey horses at age 5 years or more. Generally, benign and malignant melanomas are distinguished by microscopy, but a more distinct classification would be helpful.
Objectives: The objectives of this study were to gain further evidence concerning the occurrence of melanotic tumours, and to evaluate the impact of heredity on melanoma development.
Methods: A clinical study was conducted on a defined population of 296 grey horses of Lipizzaner breed. Individuals were classified according to theirstage of disease using a 0–5 scale. Heritability was estimated on a sample of 296 grey horses with pedigrees traced back as far as 32 generations.
Results: Of the 296 horses, dermal melanomas were present in 148 horses (50%), 68 of which were more than age 15 years; 51 of these were melanoma‐bearing. In 75.6% of cases, melanotic tumours were detected underneath the tail. Although melanoma‐bearing grey horses were encountered up to stage 4, none of the affected individuals suffered any severe clinical effect or was handicapped in performance. Statistical analysis revealed highly significant effects of stud and age (P<0.0001), explaining 28% of the total variability.
Conclusions: In contrast to melanomas in solid‐coloured horses characterised by early metastases, melanomas in grey horses showed less malignancy. Affected individuals often had encapsulated nodules or structures similar to human blue nevi. Grey horse‐specific genetic factors inhibiting metastatic processes may be responsible for this phenomenon.
Potential clinical relevance: Although the obtained heritability estimate of 0.36 with a standard error of 0.11 indicates a strong genetic impact on the development of melanoma in ageing grey horses, a possible influence of the genes with large effects was also suggested. Therefore, further analysis is required of melanoma development in the ageing grey horse.
Mandibular condylectomy, including meniscectomy, is an acceptable treatment option for advanced TMJ septic arthritis and allowed return of normal masticatory function.
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