Post mortem survey of dental disorders in 349 donkeys from an aged population (2005-2006). Part 1: prevalence of specific dental disorders

REASON FOR PERFORMING STUDY: Donkey dental disorders are being recognised with increased frequency worldwide and have important welfare implications; however, no detailed investigations of dental disorders in donkeys appear to have been published. OBJECTIVES: To determine the prevalence of specified dental disorders in donkeys by performing a prospective post mortem study on donkeys that were subjected to euthanasia or died for other reasons at the Donkey Sanctuary, UK. METHODS: Post mortem examinations were performed on 349 donkeys over an 18 month period, 2005-2006. The presence and extent of specified dental disorders were recorded and these data analysed to determine their prevalence and common locations. RESULTS: A high prevalence (93%) of disorders was noted in the population with a median age of 31 years. In particular, cheek teeth diastemata (85% prevalence) were very common, often associated with advanced periodontal disease. Other disorders observed included missing teeth (in 55.6% of donkeys), displaced teeth (43%), worn teeth (34%), local overgrowths (15%), focal sharp overgrowths (3%) and dental-related soft tissue injuries (8%). CONCLUSIONS AND POTENTIAL RELEVANCE: Aged donkeys have a high prevalence of significant dental disease, especially cheek teeth diastemata. These findings highlight the importance of routine dental examinations and prophylactic dental treatments to improve the dental health and welfare of donkeys.     

Clinical dental examinations of 357 donkeys in the UK. Part 1: Prevalence of dental disorders

Reasons for performing study: Dental disorders have a high prevalence in older donkeys and horses, but the nature and pathogenesis of many of these disorders have yet to be established. Objectives: The identification and determination of the prevalence of important dental disorders in different age groups in a large single population of donkeys, to establish a better understanding of the nature and pathogenesis of these disorders. Methods: A prospective cross‐sectional study was performed on the donkey population at The Donkey Sanctuary with detailed oral examinations of 357 donkeys within 7 different age groups (age range 2–53 years) recorded. Results: The prevalence of dental disease in all donkeys was 73%, increasing in prevalence from 28% in the youngest to 98% in the oldest age group. There was an increase in prevalence of commonly recognised dental disorders with increasing age, such as: diastemata (3.8% in youngest to 86% in oldest group); missing teeth (0–56%); overgrown teeth (15–86%); worn teeth (8–84%); displaced teeth (0–38%); and periodontal disease (0–28%). Conclusions: There was a significant increase in the prevalence of dental disorders with increasing age with the largest significant increase for most dental disorders occurring in the 15–20 year age group. Potential significance: Most dental disorders significantly increase in prevalence in the 15–20 year age group and, therefore, prophylactic geriatric dental treatment in donkeys should be commenced from age 15 years.     

Post mortem survey of dental disorders in 349 donkeys from an aged population (2005-2006). Part 2: epidemiological studies

REASON FOR PERFORMING STUDY: Dental disorders have recently been recognised as having major clinical and welfare implications in donkeys. However, no investigation appears to have examined the association of dental disorders with managemental factors and any intercurrent illness. OBJECTIVES: To determine the association of dental disorders observed in a post mortem study with age group, body condition score, time since last dental treatment, feeding and the illness that necessitated euthanasia or caused death. METHODS: A prospective study documented the type and prevalence of dental disorders in 349 mainly aged donkeys (median estimated age of 31 years) that were subjected to euthanasia over an 18 month period in 2005'Aì2006. The estimated age, body condition score, supplemental feed status, time since last dental treatment and nature of the intercurrent disease that necessitated euthanasia or caused death were also recorded. Multivariable analysis was performed to examine associations of these factors with specific dental disorders and between specific dental disorders. RESULTS: There was a high prevalence (93.4%) of significant dental disease. Age group was significantly associated with the presence of dental disorders and an older age range was a high risk factor for the presence of cheek teeth (CT) diastemata. There was a significant association between the presence of CT diastemata and the concurrent presence of displaced, missing and worn CT. There was also a significant association between the presence of diastemata and colic. CONCLUSIONS AND POTENTIAL RELEVANCE: Aged donkeys have a high prevalence of dental disorders especially of CT diastemata. Dental disorders and, in particular, the presence of CT diastemata were significantly associated with colic. Routine, prophylactic dental treatments should be performed, especially in aged donkeys.     

Clinical dental examinations of 357 donkeys in the UK. Part 2: Epidemiological studies on the potential relationships between different dental disorders,and between dental disease and systemic disorders

Reasons for performing study: Dental disease has been shown to be a risk factor for weight loss and colic in horses. No extensive clinical studies in donkeys have investigated the potential relationship between different dental disorders, or between dental disease and systemic disorders. Objectives: To determine possible associations between dental disease and body condition score, weight loss, the need for supplemental feeding and prevalence of colic in donkeys of all ages, and to gain a better understanding of the pathogenesis of dental disease by the determination of associations between different dental disorders. Methods: A prospective cross‐sectional analysis of clinical dental examinations of 357 donkeys in The Donkey Sanctuary, Sidmouth was performed. Other epidemiological factors such as estimated age group, body condition score, weight loss, medical history and supplemental feeding were also recorded, and multiple regression analyses were performed to determine possible associations. Results: Donkeys from older age groups were more likely to have dental disease, poor body condition score and suffered previous colic episodes. The presence of dental disease was also significantly associated with weight loss, colic, low body condition score and the need for supplemental feeding. The presence of diastemata, periodontal disease, wave mouth, smooth mouth and step mouth are frequently associated with the presence of other dental disorders. Conclusions: In addition to oral‐related pain, dental disease can cause significant systemic disorders and so has increased welfare implications in donkeys. Some dental disorders promote the development of other types of dental abnormalities and thus increase the severity of dental disease in individual animals. Potential significance: Effective treatment of dental disorders slows down the progression of dental disease and decreases the risk of developing some medical disorders such as colic and weight loss that are associated with dental disease.     

Polyodontia in donkeys

Polyodontia is defined as the presence of teeth in excess of the normal dental formula. In equids, supernumerary teeth are uncommon but, when present, are usually located mainly in the caudal aspects of the cheek teeth rows (distomolars), also being found adjacent to normal cheek teeth or even in an ectopic location. It is believed that this disorder is a result of an inappropriate differentiation of dental germinal tissue during gestational development, with external trauma also acting as an initiating factor, when teeth germs are affected. The presence of these abnormal teeth can lead to axial displacement, dental overgrowths, dental‐related soft tissue damage, diastemata formation, periodontal disease and development of secondary sinusitis. A large prospective, cross‐sectional study was performed in 800 donkeys, with the aim to investigate the prevalence and aetiopathogenesis of clinically diagnosed oral and dental disorders. Polyodontia was recorded in 2.25% of the donkeys, presenting 36 supernumerary teeth, with 2.80% being incisors and 97.20% cheek teeth, with prevalence increasing with age. The caudal aspects of the maxillary cheek teeth rows were the most common locations for supernumerary teeth development (distomolars). The mandible was far less commonly affected than the maxilla. Although polyodontia is uncommon in donkeys, it should be considered in the differential diagnosis of dental disease. A methodical oral examination and a complete radiographic survey of the entire dental arcades are crucial for a correct early diagnosis and treatment plan implementation. The increasing prevalence of fully erupted supernumerary teeth recorded in older groups suggested a late onset eruption process, and therefore, in donkeys undergoing regular dental prophylaxis, the presence of previously unnoticed supernumerary teeth should always be sought.     

A Clinical Survey Evaluating the Prevalence of Incisor Disorders in Zamorano-Leonés and Mirandês Donkeys (Equus asinus)

Recent clinical and post-mortem studies documented a high prevalence of dental disorders in donkeys, but less information appears to be available specifically about incisor disorders in donkeys. A study to investigate the prevalence of oral and dental disorders affecting incisor teeth was performed, in two endangered breeds of donkeys: the Mirandês Donkey and the Zamorano-Leonés Donkey, through a prospective cross-sectional study in 800 donkeys, divided in 7 age groups (ranging 0-34 years), in 86 villages inside their geographic area of distribution, thinking on welfare and genetic preservation issues. The 74% of donkeys suffer from incisors disorders, ranging from 56.8% in the youngest group to 90.3% in group 7. Craniofacial abnormalities (49.25%), abnormalities in the occlusal surface (21.63%), fractures (17%), periodontal disease (16.13%) and diastemata (14.38%) were the main disorders recorded. Incisors disorders are significant, presenting at a much higher prevalence when compared to other studies involving the incisor teeth of equids, affecting all ages but particularly in older animals. This study provide essential information in dentistry applied to donkeys but also highlighted the importance of regular dental care in endangered breeds, improving their welfare and preserving a unique genetic heritage.     

An Epidemiological Study on Orodental Disorders in 3,791 Working Donkeys in Egypt: Prevalence and Risk Factors

Orodental disorders are common in equidae and can lead to serious clinical complications. This study determines the prevalence rate (PR) of orodental disorders in working donkeys in Egypt and their potential risk factors. During 4 years, 3,791 donkeys were examined in six Egyptian governorates. Full case history and thorough clinical and oral examinations were performed. Radiography and oroendoscopy were undertaken whenever possible. All data were statistically analyzed using Poisson generalized linear models to compare PR among governorates, sex, years, body condition score, and age groups and to determine the potential risk factors. Of 3,791 examined donkeys, 954 donkeys (25.17%) had orodental disorders. The PRs of acquired disorders were 9.81% sharp enamel points, 5.86% buccal ulcers, 4.88% hook, 4.70% overgrown teeth, 4.19% periodontal disease, 3.11% ramp, 2.60% dental caries, 2.37% dental calculus, 2.30% diastema, 2.06% step mouth, 2.00% soft tissue injuries other than buccal ulcers, 1.77% worn tooth, 1.37% loose tooth, 1.29% exaggerated transverse ridge, 1.24% fractured teeth, 0.82% missing teeth, 0.69% wave mouth, 0.50% molar table angle change, and 0.45% wolf tooth overgrowth. The PRs of the congenital disorders were 1.90% displaced teeth, 1.37% deviated teeth, 0.58% retained teeth, 0.16% overbite, 0.16% underbite, 0.11% supernumerary teeth, and 0.11% premolar cap. The risk factors significantly associated (P < .05) with the orodental disorders were age and sex of the animal, geographic location, and year of examination. This study provides a database for future studies on orodental disorders and for designing effective preventive and therapeutic strategies for these disorders in donkeys.     

Clinical dental findings in 203 working donkeys in Mexico

Clinical dental examinations of 203 unsedated working donkeys in tropical and temperate climatic areas in Mexico revealed a high prevalence (62%) of dental disease with sharp enamel points present in 98% of the animals. More significant dental disorders (diastemata, 4%; overgrown teeth, 18%; worn teeth, 16%; missing teeth, 0.5%; displaced teeth, 1.5%; fractured teeth, 2%) with welfare implications that required immediate treatment were also present in 18% of donkeys.The high prevalence of buccal ulcers (14.3%) and calluses (13.3%) present in this population was believed to be due to the high prevalence of sharp enamel points in conjunction with the use of tight nose bands and head collars. Dental disease was significantly associated with age groups, but not with body condition score or to the climatic area where the donkeys lived. As part of more general examinations, 81% of donkeys that had faecal egg counts performed, had parasite burdens which mainly showed a moderate level of infection. This study concluded that dental disease is a welfare concern in working donkeys in Mexico.     

Coagulation profiles of healthy Andalusian donkeys are different than those of healthy horses

Background: Coagulation disorders are frequently diagnosed, especially in hospitalized equidae, and result in increased morbidity and mortality. However, hemostatic reference intervals have not been established for donkeys yet. Objectives: To determine whether the most common coagulation parameters used in equine practice are different between healthy donkeys and horses. Animals: Thirty‐eight healthy donkeys and 29 healthy horses. Methods: Blood samples were collected to assess both coagulation and fibrinolytic systems by determination of platelet count, fibrinogen concentration, clotting times (prothrombin time [PT] and activated partial thromboplastin time [aPTT]), fibrin degradation products (FDP) and D‐Dimer concentrations. Results: PT and aPTT in donkeys were significantly (P < .05) shorter than those of horses. In contrast, FDP and D‐Dimer concentrations were significantly (P < .05) higher in donkeys than in horses. Conclusions and Clinical Importance: The coagulation parameters most commonly determined in equine practice are different in donkeys compared with horses. Thus, the use of normal reference ranges reported previously for healthy horses in donkeys might lead to a misdiagnosis of coagulopathy in healthy donkeys, and unnecessary treatments in sick donkeys. This is the first report of normal coagulation profile results in donkeys, and further studies are warranted to elucidate the physiological mechanisms of the differences observed between donkeys and horses.     

Pharmacology and therapeutics in donkeys

Therapeutics are often administered to donkeys based on dosage and intervals recommended for horses because very few drugs have donkey‐specific label indications. Yet differences between donkeys and horses in drug distribution, metabolism and elimination have been noted for most therapeutic agents studied. These differences can be partially explained by the donkey's unique physiology. Since their ancestors evolved in a desert environment, the modern donkey exhibits qualities that allow them to tolerate dehydration better than the horse and recover more quickly from its effects. Fluid balance and body water compartment partitioning differ from the horse and may have implications regarding drug distribution. Since donkeys are preferential browsers, differences in diet may have influenced evolutionary differences in metabolic disposition of drugs. It is important to acknowledge these differences when designing dose regimes for donkeys based on horse protocols in order to avoid either lack of efficacy or toxicity.     

Practical feeding and condition scoring for donkeys and mules

Donkeys have evolved to thrive on highly fibrous, poor quality foodstuffs and have evolved as browsers as well as grazers. As such, they have different nutrient requirements with significantly lower energy and protein needs when compared with horses. Dietary management of donkeys is essential when kept in a temperate climate as they are prone to obesity and related disorders. A diet based on fibrous forages and limited grazing is usually sufficient for the majority of donkeys and mules. Specialist feeding is discussed in this article.     

Equine developmental dental disorders

The true prevalence of developmental dental disorders in horses is unknown, but from a clinical perspective, dental dysplasia of varying degrees of severity appears to be far more common than developmental abnormalities of tooth numbers. The latter includes the presence of increased numbers of teeth (supernumerary teeth), which in turn appears more prevalent than reduced numbers of teeth (hypodontia or anodontia). This clinical commentary briefly reviews all three types of developmental dental disorders from a clinical viewpoint.     

Donkey dental anatomy. Part 1: Gross and computed axial tomography examinations

Post-mortem examination of 19 donkey skulls showed that donkeys have a greater degree of anisognathia (27% width difference between upper and lower jaws) compared to horses (23%). Teeth (n=108) were collected from 14 skulls and examined grossly and by computed axial tomography (CAT). A greater degree of peripheral enamel infolding was found in mandibular cheek teeth (CT) compared to maxillary CT (P<0.001). A significant increase in peripheral cementum from the apical region to the clinical crown was demonstrated in all CT (P<0.0001). All donkey CT had at least five pulp cavities with six pulp cavities present in the 06s and 11s. A new endodontic numbering system for equid CT has been proposed. A greater occlusal depth of secondary dentine (mm) was present in older donkeys (>16 years) than in the younger (<15 years) donkeys studied. Based on gross and CAT examinations, donkey dental anatomy was shown to be largely similar to that described in horses.     

Diagnostic orientation values for ACTH and other parameters for clinically healthy donkeys and mules (insulin,triglycerides, glucose,fructosamines, and ɣ-GT)

Pituitary pars intermedia dysfunction is the most prevalent endocrine disease in horses. Although donkeys and mules may also be affected, only a few data have been published. Reference values for diagnostic parameters, such as adrenocorticotropic hormone (ACTH), are especially scarce or even lacking. Therefore, in the present study, available data from the literature have been verified and completed to facilitate a reliable diagnosis. Clinical inspections and haematological and biochemical examinations were carried out four times in a three-month interval (February to November) in 44 donkeys and 31 mules. Data from clinically healthy animals were used as an orientation. Plasma ACTH concentrations showed seasonal changes in both animal groups. However, it was generally higher in donkeys than mules. Although blood glucose (EDTA plasma) showed no difference between groups, serum insulin concentrations were consistently higher in donkeys. Serum fructosamine levels were slightly higher in mules, whereas, in some cases, serum triglyceride levels were considerably higher in donkeys. Serum gamma-glutamyltransferase showed a striking peak in mules in August, whereas the remaining gamma-glutamyltransferase values were lower compared to donkeys. By comparing donkeys and mules, the present work reveals differences in various blood parameters which should be considered for diagnoses and future studies.     

Post mortem survey of peripheral dental caries in 510 Swedish horses

Reasons for performing study: Peripheral caries (PC) of equine teeth is a poorly described disorder that can cause serious clinical problems if it progresses. Objectives: To assess the prevalence, sites and severity of PC in a population of Swedish horses. Methods: A post mortem study of 510 equine skulls was performed in 2 Swedish equine abattoirs. Results: PC only affected the cheek teeth (CT) and was present in 6.1% (31/510) of skulls. It affected mainly the peripheral cementum, and 87% of PC in the 29 affected mature horses occurred in the 3 caudal CT (Triadan 09‐11). Concurrent infundibular caries involving most maxillary CT (mean 9.7/skull) was present in 32% of skulls affected with PC. Trotting horses (mean age 8.1 years) believed to be on a high concentrate and silage diet were preferentially affected with PC in this population. Food was usually tightly adherent to the PC lesions and this feature may have promoted the progression of the disease. Significantly increased levels of diastemata were present in PC‐affected horses, and periodontal disease was present in areas adjacent to some PC lesions. Conclusions: PC is a relatively common disorder of horses under certain management conditions that can progress to cause serious dental disorders, especially if concurrent, widespread infundibular caries is present. Potential relevance: Equine clinicians should be aware of this significant dental disorder and research into its aetiopathogenesis, possible prevention and treatment are required.     

RADIOGRAPHIC APPEARANCE OF THE FEET OF MAMMOTH DONKEYS AND THE FINDING OF SUBCLINICAL LAMINITIS

All feet of 10 clinically sound mammoth donkeys (Group I) were radiographed to determine the appearance of the distal phalanx. The distal phalanges had blunted to concave-shaped dorsal solar margins which varied in appearance from slight to pronounced. The distal phalanges of the forefeet were wider than those of the hindfeet, and also were positioned a greater distance from the dorsal aspect of the hoof wall. The greater distance between the dorsal aspect of the hoof wall and the distal phalanges seemed related to the presence of a periosteal-like bony proliferation on the dorsum of the distal phalanx. This bony proliferation occurred in those distal phalanges which also had radiographic findings consistent with pedal osteitis. Next, all feet of 5 additional mammoth donkeys (Group II) that were to be necropsied for various reasons, were examined similarly to Group I, necropsied and found to have laminitis. Only 2 of these 5 donkeys had been lame; only one had rotation of the distal phalanges (in the forefeet). Radiographic data from the 4 donkeys without rotation seemed most similar to that found in those Group I donkeys which had periosteal reactions on their distal phalanges. Conclusions from this study were that: 1) feet of mammoth donkeys have some anatomic differences from those of domestic horses, 2) subclinical laminitis and pedal osteitis can occur in mammoth donkeys, 3) rotation of the distal phalanx occurs in some, but not all laminitic donkeys, 4) laminitic changes may be more pronounced in their fore than in their hindfeet, and 5) additional studies of donkeys need to be done, examining both proven normal and confirmed laminitic feet.     

Treatment of oromaxillary fistulae in nine standing horses (2002–2006)

Reasons for performing study: There is minimal published information on equine oromaxillary fistulae that are unrelated to cheek teeth (CT) repulsion or on the conservative treatment of these atypical fistulae. Objectives: To report equine oromaxillary fistulae unrelated to CT extraction and describe their management in standing horses. Methods: Case details of oromaxillary fistulae of atypical aetiology occurring at 2 referral centres between 2002–2006, including their treatment and response to treatment were examined. Results: Nine cases of oromaxillary fistula were recorded, mainly in aged horses (median 22 years). Fistulae were associated with CT diastemata in 7 cases, fractured CT in one and a central defect in a worn CT in another. After removing food and exudate from the sinuses, 6 cases were treated successfully by filling the diastema or dental defect with polymethylmethacrylate (PMMA). Following dental extraction, the other 3 cases were treated successfully by use of PMMA alveolar packing. Conclusion: Older horses can spontaneously develop oromaxillary fistulae, usually secondary to CT diastemata. In the absence of apical infection, this disorder can usually be treated successfully in standing horses by treating the sinusitis and sealing the oral aspect of the diastema with PMMA. Potential relevance: Older horses with sinusitis should be assessed for the presence of CT diastemata and oromaxillary fistulae. If detected, these disorders can be treated successfully in the standing horse.     

A MACROSCOPIC AND RADIOLOGIC INVESTIGATION OF DENTAL DISEASES OF THE DOG

The type and frequency of dental diseases and disorders were determined in 162 randomly selected dogs available for necropsy. There were 82 males and 80 females ranging in age from seven months to 14 years. There were 150 purebred dogs (50 different breeds) and 12 mongrels. Only four breeds were represented by ten individuals or more: Poodles (Miniature and Toy), German Shepherds, Dachshunds, and Boxers. The oral cavity was examined macroscopically, and missing teeth, dental caries, dental calculus (tartar), and gingival epulides were recorded as to frequency and distribution. After macroscopic examination of the oral cavity, the head of each dog was sawed at the midline, fixed in formalin, and radiographed. The frequency, severity, and distribution of marginal periodontitis, periapical destruction, and root resorption were recorded. The most frequently noted disease was periodontitis, which increased in frequency and severity with increasing age of the dogs. The disease varied markedly among and within different breeds. Small dogs were more often affected with periodontitis than large dogs. Periapical destruction was a common finding. Caries and root resorption were less common. Missing teeth was a frequent disorder regardless of age. Most of the dogs had dental calculus.     

Investigating the opinions of donkey owners and veterinary surgeons towards pain and analgesia in donkeys

The aim of this questionnaire‐based study was to identify which analgesics are currently prescribed to donkeys in clinical practice and to collect opinions from veterinary surgeons and donkey owners on the importance of different pain‐related behaviours in donkeys. Questionnaires were completed by 143 veterinary surgeons and 93 donkey owners. Phenylbutazone, flunixin, detomidine and butorphanol were reported as the most frequently used analgesics in donkeys. Most veterinary surgeons reported administering these drugs at the horse dose rate and dosing interval, which may be inappropriate in the donkey. Four pain‐related behaviours were identified as very important by veterinary surgeons and owners: dullness for colic‐associated pain, keeping the foot lifted, and lameness for foot and limb pain and inability to chew properly for head and dental pain. This is a more limited behavioural repertoire than has recently been identified to be associated with pain in the donkey and suggests that the respondents were reporting perceived wisdom as to what people think are the behavioural signs associated with pain or were not interpreting pain‐related behaviours correctly.     

Common helminth infections of donkeys and their control in temperate regions

Roundworms and flatworms that affect donkeys can cause disease. All common helminth parasites that affect horses also infect donkeys, so animals that co‐graze can act as a source of infection for either species. Of the gastrointestinal nematodes, those belonging to the cyathostomin (small strongyle) group are the most problematic in UK donkeys. Most grazing animals are exposed to these parasites and some animals will be infected all of their lives. Control is threatened by anthelmintic resistance: resistance to all 3 available anthelmintic classes has now been recorded in UK donkeys. The lungworm, Dictyocaulus arnfieldi, is also problematical, particularly when donkeys co‐graze with horses. Mature horses are not permissive hosts to the full life cycle of this parasite, but develop clinical signs on infection. In contrast, donkeys are permissive hosts without displaying overt clinical signs and act as a source of infection to co‐grazing horses. Donkeys are also susceptible to the fluke, Fasciola hepatica. This flatworm can be transmitted, via snails and the environment, from ruminants. As with cyathostomins, anthelmintic resistance is increasing in fluke populations in the UK. A number of the anthelmintic products available for horses do not have a licence for use in donkeys, and this complicates the design of parasite control programmes. As no new equine anthelmintic classes appear to be near market, it is important that the efficacy of currently effective drugs is maintained. It is important that strategies are used that attempt to preserve anthelmintic efficacy. These strategies should be based on the concept that the proportion of worms in a population not exposed to anthelmintic at each treatment act as a source of ‘refugia’. The latter is an important factor in the rate at which resistance develops. Thus, it is imperative that parasite control programmes take into account the need to balance therapy to control helminth‐associated disease with the requirement to preserve anthelmintic effectiveness.