Hypodontia of Permanent Incisor Tooth in a Crioulo Horse

Case Report

Austin J Radiol. 2015;2(5): 1027.

Hypodontia of Permanent Incisor Tooth in a Crioulo Horse

Pizzigatti D¹, Jacques RSPE², Martins CF³,Pimentel C³ and Álvarez LEC4*

¹1Large Animal Clinics and Surgery Service, School of Veterinary Medicine, Brazil

²Autonomous, Pelotas, Rio Grande do Sul, Brazil

³DepartmentofVeterinaryClinic, SchoolofVeterinary,Brazil

4ImagingDiagnosis Service, SchoolofVeterinary Medicine, Brazil

*Corresponding author: Luis Emiliano Cisneros Álvarez, Imaging Diagnosis Service, Schoolof Veterinary Medicine, FIO, Ourinhos, São Paulo, Rodovia BR-153, KM338+420m, Bairro Agua do cateto, Zip code 19909- 100, Brazil

Received: March 28, 2015; Accepted: July 08, 2015; Published: July 10, 2015


Tooth hypodontia is a rare condition in horses that might cause underdevelopment in young animals, occlusion imbalances, masticatory abnormalities and decrease in performance. Disregarding its embryological or traumatic nature, tooth hypodontia is expected to be identified late in disease. Hence, this anomaly should be investigated as a part of the routine dental examination, especially in absence of any dental piece. Equine hypodontia or anodontia has not been previously described. This report presents a case of hypodontia of a permanent incisor tooth in a crioulo horse revealed by radiography.

Keywords: Hypodontia; Tooth agenesis; Incisive; Permanent tooth; Horse


Odontogenesis is a complex and sensitive embryological process, which is influenced by several inherited or acquired disorders affecting either the permanent or deciduous teeth [1-5]. Abnormalities of dental development and/or eruption in animals might cause irregular tooth wear and so occlusal imbalances, which often causes a variety of clinical signs including foul breath, weight loss, colic, and dropping feed [3,6-9].

Data on the qualitative and quantitative anomalies in dental eruption in animals have been reported since ancient times by Hippocrates and Gaius PliniusSecundus [10]. Furthermore, hypodontia was already identified in a fossil mammal (Perissodactylatapiridae) from the Eocene in Spain [5,11]. Other developmental abnormalities such as polyodontia and tooth agenesis have been identified in horses [1,3,6,11].

Tooth agenesis is defined as the failure in formation of one or more teeth due to developmental defects [12,13], which may be caused by genetic and/or environmental factors. In animals, as in humans, this condition is more commonly observed in females than in males [5,14-18]. Although there is ambiguity in the use of the term “tooth agenesis” [4,19,20], it is subdivided into oligodontia, i.e., absence of more than six teeth; hypodontia, i.e., absence of up to six teeth; and anodontia or absence of all teeth [1,4,6,11,13,15,21]. Tooth agenesis frequently affects permanent teeth, predisposing to imbalanced occlusion due to overgrowth of the opposing teeth [8,22,23].

There are a few reports on tooth agenesis in horses [1-3,6,7,11,22]. In humans, this entity is considered as the most prevalent congenital craniofacial malformation (ranging from 1.6 to 9.6% for permanent teeth and from 0.5 to 0.9% for deciduous teeth) [13]. Whenever talking about hypodontia of the third molar, it can be identified in up to 25% of the human population [15,16]. Current research on physiopathology and treatment of tooth agenesis are based on tissue engineering [16,24].

Although its pathogenesis is not entirely understood [11], ectodermal dysplasia is one of the differential diagnoses in cases of oligodontia in humans and involves a series of inherited diseases affecting several ectodermal-origin tissues such as teeth, hair, and nails [6,7,25]. In human medicine, oligodontia of deciduous and permanent incisor teeth was described in two sisters [25]. However, oligodontia is extremely uncommon in horses. Ramzan et al. described oligodontia associated with ectodermal dysplasia syndrome in a thoroughbred foal [11]. Oligodontia in a foal with a congenital maxillary tumor was also reported [26].

Hypodontia is defined as teeth absence caused by anomalous differentiation of the dental lamina and tooth bud, and can be triggered by trauma, infection or senile wear [19,24]. Currently, there is no report on hypodontia or anodontia in horses [1-3,6,7]. This paper reports a case of hypodontia presumptively caused by agenesis of the permanent maxillary central incisor tooth in a crioulo horse.


A three-year-old crioulo stallion was attended due to bad breath, and 502 and 602 incisor trauma suffered approximately four months prior presentation. The owner reported that the trauma to the incisor teeth was caused by cribbing and sucking in air. The horse was trained for show jumping (approximately two hours daily). However, it was mostly kept in stall wearing a halter to prevent cribbing. The animal’s diet consisted on a combination of lucernehay (Medicago sativa L.) and a commercial feedstock, which were provided three times per day.

Initial approach revealed a docile temper. However, physical appraisal revealed sialorrhea, difficulties to eat, and halitosis. Heart rate, respiratory rate, body temperature, capillary filling time, and pulmonary and abdominal auscultation were within normal limits. Oral examination showed fracture and root retention of 502 and 602 along with vestibular and mesial wear of the opposite 802 and 702 incisor teeth (Figure 1A and 1B).

Citation: Pizzigatti D, Jacques RSPE, Martins CF, Pimentel C and Álvarez LEC. Hypodontia of Permanent Incisor Tooth in a Crioulo Horse. Austin J Radiol. 2015;2(5): 1027. ISSN :2473-0637