High populations of donkeys are distributed all over the world specially Egypt that has 1.6 million donkeys1.
In many countries, oro-dental disorders in equine are very common welfare problems especially donkeys2-5. Previous studies have been investigated that donkeys are very stoic animals and a high population of them suffers from various asymptomatic oro-dental disorders6.
Congenital defects and the management regime enforced through domestication are the most common causes for development of oro-dental disorders7.
Although there are significant advances in oral examination of donkeys on the last decade6, a complete visual examination especially the caudal oral structures remains difficult. This difficulty is due to the small mouth opening, long oral cavity, large and powerful tongue that hinders visualization and restricted buccal space with tight adherence of the cheeks and skin to the skull8,9. Recent diagnostic tools including radiography2, sinoscopy8, gamma scintigraphy10 and computed tomography11 have been used with some limitations for diagnosis of oro-dental disorders in donkeys. Therefore, intra-oral endoscopy has been suggested as a more specific and sensitive diagnostic tool than other conventional examination methods, particularly for disorders of the caudal oral cavity12.
This study was designed in order to facilitate the early and efficient diagnosis of the oro-dental disorders in donkeys. To achieve this target, the authors hypothesized that endoscopy could play an important role in the diagnosis of oro-dental disorders in donkeys which will greatly help the veterinarians in the practice. Therefore, this study was designed to determine the role of oral endoscopy as a new diagnostic tool for oro-dental disorders in donkeys.
MATERIALS AND METHODS
Animals: The study was carried out on 25 donkeys during the period extending from January to December 2016. These animals included 20 males and 5 females. The age of these donkeys ranged between 1 and 8 years. These donkeys were admitted to the surgery clinic at Faculty of Veterinary Medicine, Cairo University, Egypt. All of the donkeys had common signs of oro-dental disorders including; loss of appetite, loss of weight, disturbed mastication, prolonged food intake, excessive salivation, halitosis and quidding.
Clinical examination: Under general anesthesia using intravenous administration of Xylazine HCl (Xylajet®, ADWIA, Egypt) at a dose of 1 mg kg1 b.wt., and Thiopental sodium (Thiopental sodium®, EPICO, Egypt) at a dose of 5 mg kg1, full visual and manual examinations were carried out for gingiva, teeth, hard palate, soft palate and tongue. The visual and manual examinations were carried out with the aid of a strong headlight, a long handled equine dental mirror and a mouth gag.
Endoscopic examination: Before video endoscopic examination, the mouth was washed several times with water for good images. Under the same general anesthesia, oral endoscopic examination was performed for detection of any abnormal lesion by using video endoscope, protected with a rigid metal sheath and recorded onto an analogue videotape. The endoscopic images were captured for oral cavity of the examined donkeys using video-endoscope unit (Eickemeyer-China) supplied with halogen light source (Vet Lux-150 Watt) and insertion tube (3 m length). The endoscopic examination was begun with incisors, canines, hard and soft palates, the occlusal and caudal surfaces of the cheek teeth, gingiva and tongue.
Laboratory diagnosis: Samples were collected from the oral ulcerative lesion for detection of Candida species.
Quantitative samples cultures were collected by sterile swap from the oral ulcerative lesions using standard laboratory methods. Colonies suspicious for Candida spp. were identified using CHROMagar™ Candida plates (Laboratorios Conda, Biotech Spain) according to the manufacturers guidelines, Isolates were then identified to their species level with the RapID™ Yeast Plus system (Remel, KS).
Treatment: All donkeys were treated either with conservative or surgical treatment as usual.
The results of the present study revealed that all of the presented donkeys (25) suffered from either single (N = 3) or mixed oro-dental disorders (N = 22). The recorded oro-dental disorders and their prevalence were collected in (Table 1).
Teeth disorders: Periodontal disease was the most common disorder in the examined donkeys. It was reported in 22 donkeys representing 88% of the total examined donkeys. All stages of the periodontal disease with various degrees of dental tartar were recorded in the examined animals (Fig. 1a). Dental tartar was recorded in 20 donkeys representing 80% of the total examined donkeys.
Video endoscopic images of the oral cavity showing the different recorded dental disorders in the examined donkeys (a) Dental tartar, periodontal disease and sharp teeth (black arrows) at the lingual surface of mandibular molars, (b) Diastema with impacted food between decayed mandibular molars (arrows) and (c) Between the mandibular and maxillary incisors (arrows), (d) Dental caries (white arrows), sharp teeth at the buccal surface of upper molars (black arrows) and severe dental tarter at the mandibular molars, (e) Dental caries at the masticatory surface of mandibular molars (white arrow) and (f) Impacted (unerupted) deciduous 3rd incisor (corner) tooth with swelling and ulceration at its site (black arrow)
|Table 1:||Prevalence of oro-dental disorders in the examined donkeys
Cheek teeth were the most common location of dental tartar in the examined donkeys (Fig. 1a).
Diastema was reported in 17 donkeys representing 68% of the total examined donkeys. This diastema was found between cheek teeth (Fig. 1b) in 10 donkeys (58.8%) and between incisors (Fig. 1c) in 7 donkeys (41.2%). Various degrees of periodontal disease were seen in the involved teeth of diastema (Fig. 1b).
Oral endoscopy revealed dental caries in 10 donkeys represented 40% of the total examined donkeys. The magnification power of the endoscope facilitated the observation of the early stage and various degrees of dental caries in the examined donkeys (Fig. 1d, e).
Sharp teeth were observed in 9 donkeys representing 36% of the total examined donkeys. Oral endoscopy revealed sharpness in the buccal surface of the upper cheek teeth and lingual surface of the lower cheek teeth (Fig. 1a, d). Additionally, oral endoscopy showed several lacerations in the oral cavity.
Oral endoscopy in a 2-year-old female donkey showed impacted (unerupted) deciduous 3rd incisor (corner) tooth with swelling and ulceration at its site (Fig. 1f).
Hard and soft palates disorders: Hard palate candidiasis was clearly seen by oral endoscopy in 4 donkeys representing 16% of the total examined donkeys. The age of the affected donkeys was 1-3 years. Brownish ulcerative lesions were seen at the hard palate of the affected donkeys (Fig. 2a). Laboratory investigation of the collected samples revealed green colonies of Candida albicans (Fig. 2b).
Recent wounds of the hard and soft palates were clearly observed by oral endoscopy in 3 donkeys representing 12% of the total examined donkeys. These wounds were either single (Fig. 2c) or multiple (Fig. 2d). Old ulcerative wound was also seen during oral endoscopy in a female donkey representing 4% of the total examined donkeys (Fig. 2e).
Video endoscopic images of the oral cavity showing the different recorded disorders of the soft tissues in the examined donkeys (a) Video endoscopic image showing hard palate candidiasis in a 3-years-old donkey showing brownish, ulcerative lesion (arrow), (b) Candida albicans showing green colour colonies on CHROM agar™ Candida medium, (c) Video endoscopic images of the hard palate in the examined donkeys showing single recent wound (arrow), (d) Double recent wounds (arrows), (e) Old ulcerative wound (arrow) and (f) Gingival wound (arrow)
Laboratory investigation revealed no Candida albicans in this ulcer.
Gingival wounds: Oral endoscopy revealed gingival wounds in 3 donkeys representing 12% of the total examined donkeys. All of these wounds were recent (Fig. 2f).
In the present study, oral endoscopy was used successfully for diagnosis of periodontal disease, dental tartar, diastema, dental caries, sharp teeth, oral candidiasis, wounds of hard and soft palates, gingival wounds and unerupted tooth in donkeys. The use of endoscopy is easy, quick and accurate technique for diagnosis of disorders in equine13. Additionally, highly detailed images are obtained by oral endoscopy due to the high magnification of the endoscope. Moreover, oral endoscopy facilitates close examination of the intra-oral structures and spaces which are difficult to access by other tools8. The only limitation is the inability of endoscopy to diagnose the disorders of apical and alveolar portions of teeth. Radiography has traditionally interest for diagnosis of the disorders of the invisible portions of teeth14,15. In this respect, other imaging techniques such as scintigraphy and computed tomography have several difficulties and inaccurate diagnosis for intra-oral structures10,11.
In contrast to Giorgis et al.5 and Dixon et al.16, who recorded dental disorders in the too old animals, the age of the presented donkeys in this study ranged between 1-8 years. This could be attributed to green grass and short fiber diet which were given to the examined donkeys. This type of diet helps in development of several dental disorders.
In the current study, periodontal disease and dental tartar were the most common disorders in donkeys. These disorders mainly involved cheek teeth. Similar findings were reported in previous studies4,17. The high prevalence of periodontal disease in the examined donkeys was attributed to periodontal food impaction adjacent to dental tartar and diastema. This is in agreement with the results of a previous study18.
A diastema is a space between two teeth, most commonly between the incisors and molars. The food is forced into this space and decayed causing gingivitis and ultimately leading to periodontal disease in the surrounding teeth. In the present study; diastema was very common (68%) in the live examined donkeys. Du Toit et al.4 and Dixon et al.16 found cheek teeth diastema in 85% of old dead donkeys. This difference in incidence is due to under diagnosis of diastema in live equine as it can be difficult to visualize. Only 41.2% of diastema included incisors and 58.8% included maxillary and mandibular cheek teeth. Similar findings were reported before4,16.
Regarding dental caries, it was identified mainly at the masticatory surface of cheek teeth. This is due to the uneven masticatory surface which keeps the food for long time and consequently decaying of the tooth occurs. This agrees with the previous results19. Borkent and Dixon20 classified dental caries in equine into; peripheral dental caries and infundibular dental caries, with peripheral caries appearing to be increasingly recognized.
Sharp teeth were reported in 36% of the total examined donkeys. This high incidence is due to anatomical consideration, maxilla is wider than mandible and feeding of the donkeys on soft food and green grass for long time. These sharp teeth cause lacerations and ulcers to the tongue and to the sides of cheek and consequently leading to painful chewing and quidding.
In the present study, oral candidiasis was diagnosed in young donkeys (1-3 years). This could be attributed to low immunity of young donkeys. In this respect, McClure et al.21 recorded immunodeficiency manifested by oral candidiasis and bacterial septicemia in foals.
Wounds of gingiva, hard and soft palates were common in the examined donkeys due to the biting habit of donkeys.
This study concludes that oral endoscopy is a beneficial new diagnostic modality for diagnosis of oro-dental disorders in donkeys. Thus a new diagnostic tool for oro-dental disorders in donkeys may be arrived at veterinary practice.
This study will help the researchers and veterinarians to uncover the critical disorders of oro-dental structures especially those of the caudal part of the oral cavity that are difficult to be diagnosed by the routine procedures.
Thanks are due to Dr. Rehab A. Elhew at Department of Microbiology, Faculty of Veterinary Medicine, Cairo University for her help in mycotic examination of the samples.