Alimentary System Flashcards
Measurement used to assess the angulation of the check tooth occlusal surface
With the mouth closed the rostral aspect of the mandible should be pushed sideways and the distance of the lateral movement of the lower incisors in relation to the upper before separation of the incisors (as the angled occlusal surfaces of opposing check teeth come into contact)
Major significance of parrot mouth
overgrowth of rostral aspect of 106 and 206 and caudal aspect of 311 and 411
describe the problem
cheek teeth slab fracture
Equine tooth anatomy
When describing disorders of the incisors and “overjet” refers to
Rostral projection of the upper incisors in a horizontal plane
What is a major significance of overjet
Affected horses commonly have overgrowths of the rostral aspects of 106 and 206 and of the caudal aspect of 311and 411
In affected foals how is overjet surgically corrected
Incisor orthodontic brace by placing steel wires (a tension band) around the upper incisors and fixing these wires around 506 and 606 (or 507 and 607) to retard growth of the premaxilla and maxilla
Best performed at around 3 months of age but it can be of value up to 8 months old
considerations of orthodontic brace when overbite is present
The tension may cause further caudoventral deviation of the upper incisors and premaxilla toward the rostral aspect of the lower incisors
In such foals a biteplate can additionally be fitted along with the orthodontic brace to promote indirect occlusion between the upper and lower incisors
Describe underbite ‘Sow Mouth”
Prognathism (under jaw, underbite) is rare in horses, except in miniature horses and is usually clinically insignificant unless there is total lack of occlusion between the upper and lower incisors
Eventually will develop a concave upper incisor occlusal surface which has been termed a frown and may develop lower 06 and upper 11 overgrowth
Retained deciduous incisors
Normally lie rostral (labial) to their permanent counterparts they can cause the permanent incisor to be displaced caudally (lingually)
Management of horse with incisor fractures
First aid - Tetanus prophylaxis and prolonged (7-10 days) antibiotics therapy, regional nerve block (mental or infraorbital nerve) followed by removal of any loose dental fragments and debridement of any exposed pulp as a main treatment when possible an endodontic treatment should be attempted
Define diastemata
Space that develops between the occlusal aspects of adjacent cheek teeth, mandibular cheek teeth are most commonly affected requiring the use of endoscopy or intraoral mirrors or obtaining 10-15 degree latero-oblique radiograph with the horse’s mouth open
best treatment for diastemata
In mature horses, widen problematic diastemata to about 4-6 mm wide on the occlusal surface
Describe rostral positioning of the maxillary cheek teeth
Common dental abnormality, invariably occurring in conjunction with overbite, eventually leading to the development of focal overgrowth of the rostral aspect of the upper 06s which may cut the cheeks and interfere with the bite
Similar overgrowth on the caudal aspect of 311 and 411 frequently go undetected and can lacerate the tongue, wear down the opposite check teeth (maxillary 11s) to gum level an even penetrate the hard palate or lacerate the greater palatine artery
Idiopathic fractures of cheek teeth
Most commonly slab fractures occur through the two lateral pulp cavities (pulp horns #1 and #2) usually upper 09s
Maxillary cheek teeth slab fractures site usually becomes filled with fibrous food, thus laterally displacing the smaller lateral cheek teeth fragments into the cheeks, causing buccal lacerations with subsequent quidding and biting problems
midline (sagittal) fractures of the maxillary cheek teeth
Occur less commonly than slab fracture
09s are most commonly affected
Believed to be secondary to advanced infundibular caries with coalescence of two carious infundibula leading to mechanical weakening, followed by fracture of the cheek teeth
List the equine dental tumors
Ameloblastoma (non-calcified epithelial tumors), ameloblastic odontoma (contains dentine, cementum, and enamel), odontoma (calcified) cementoma or more commonly combination of them (combined odontoma)
oral cavity tumors
Most common is SCC, other primary or metastatic tumors include melanoma, fibrosarcoma, hemangiosarcoma, lymphosarcoma, rhabdomyoma, rhabdomyosarcoma, and chondrosarcoma of the tongue
List the major salivary glands in the equine patient
Paired parotid, mandibular (submaxillary), and polystomatic sublingual glands, also smaller buccal, labial, lingual, and palatine salivary glands
Salivary secretions by different glands
Parotid secrete mainly serous fluids, whereas the mandibular and sublingual produce a combination of serous and mucous fluids
Describe the mandibular salivary gland
Extend from the atlantal fossa to the basihyoid bone
Most of its lateral surface is covered by the parotid salivary gland and partly by the mandible, and its medial surface covers the larynx, common carotid, vagosympathetic truck, and guttural pouch
The duct opens a few centimeters rostrolateral to the lingual frenulum at the sublingual caruncle
treatment for lacerated salivary glands
Fresh wounds of the parotid gland can be debrided and reconstructed with a multilayer closure starting with the parotid capsule, possible suture penetration to the glandular tissue provide a nidus for calculus formation and should be avoided
Primary closure of an acutely lacerated duct or a nonhealing salivary fistula is facilitated by suturing it over an intraluminal tube or by placing tree sutures to oppose the two cut ends as a triangle and suturing between the apices
options to manage chronic parotid salivary duct fistula
Surgical removal of the gland, duct ligation or chemical ablation of the gland
Discuss duct ligation
The parotid duct is located where it crosses the tendon of insertion of the sternomandibularis muscle close to its origin from the gland
2-3 heavy-gauge nonabsorbable sutures should be used and should not be tied to tightly to prevent cutting through the duct wall, the distal suture is tied first to distribute resulting back-pressure after ligation
Discuss chemical ablation
10% formalin (currently recommended), 2% chlorhexidine, 2% and 3% silver nitrate
When using 10% formalin the duct is cannulated and a ligature tied to prevent leakage
35 mL of formalin is injected through the cannula and left in place for 90 seconds and then allowed to drain out, the cannula is left in place for 36 hours
Cessation of salivary secretions occurs in 3 weeks
Describe Sialoliths
Hard concretions composed mostly of calcium carbonate and organic matter that develop within a salivary duct or less commonly gland
Affect older horses and the parotid duct is most commonly involved and usually occur singularly, typically a nonpainful, movable, firm structure is palpable on the lateral aspect of the face near the rostral end of the facial crest
Definitive treatment is removal, direct intraoral incision over the sialolith, leaving the wound to heal by second intention is preferred
Can be also removed by external longitudinal incision of the duct
Describe mucocele and ranula
Mucocele or sialocele refers to a pocket of saliva in a space not lined by epithelium
Ranula (“honey cyst”) represents a mucocele of one of the sublingual salivary glands ducts and is seen as bluish-tinged cyst on the floor of the mouth
How is the wall of the esophagus composed
4 layers (1) a fibrous layer (tunica adventitia) (2) muscular layer (tunica muscularis) (3) submucosal layer (tela submucosa) (4) and mucous membrane (tunica mucosa)
Muscular layers are striated from the pharynx to the base of the heart where they gradually blend into smooth muscle, on surgical incision separates easily into two distinct layers, the elastic inner layer composed of mucosa and submucosa freely movable within the relatively inelastic outer muscular layer and adventitia
what provides the greatest tensile strength on closure of an esophageal incision
The mucosa which is covered with stratified squamous epithelium and lies in longitudinal folds that obliterate the lumen
blood supply and innervation to the equine esophagus
Arterial supply to the cervical part originates from the carotid arteries, the thoracic and abdominal is supplied by the bronchoesophageal and gastric arteries
Innervation is derived from the ninth (Glossopharyngeal) and tenth (Vagus) cranial nerves and the sympathetic trunk as well as mesenteric ganglion cells within the muscle layers
Diagnostic imaging of the equine esophagus
Ultrasonography, radiography (esophagography) survey films are necessary
Barium paste (85% wt/vol with water 120ml) outline longitudinal mucosal folds
Liquid barium (72% wt/vol with water, 480 ml) demonstrate strictures and associated prestenotic dilation as well as space-occupying masses that displace the esophagus
Liquid barium (480 ml) followed by air (480 ml) delivered by dose syringe under pressure provides double-contrast study which gives the best definition of mucosal lesions
surgical approaches to the equine esophagus
Three surgical approaches: ventral cervical best used for esophagotomy, esophagomyotomy, and resections involving the proximal third of the cervical esophagus, ventrolateral approach recommended for placing a feeding tube in the midcervical esophagus (esophagostomy) or for approaching the distal one fourth of the cervical esophagus, thoracotomy is necessary to approach the distal half
Ventral approach to the equine esophagus
Dorsal recumbency, 10 cm skin incision, the paired sternothyroid, sternohyoid and omohyoid muscles are separated along the midline to expose the trachea and blunt separation of fascia along the left side of the trachea exposes the esophagus