Lesson 60: Disorders of the Tonsils, Pharynx and Esophagus

Tonsils: hyperplasia

diffuse "tonsillar" hyperplasia common in foals

exposure to the environment and bacteria & viruses → chronic irritation reaction

Disorders of the tonsils: Lymphoid necrosis

feline panleukopenia

canine parvoviral infection

canine distemper

BVD

Tonsillitis

red, swollen

causes: systemic disease (e.g., ICH), local infection

Tonsils: neoplastic dieseases

Lymphosarcoma (L)

Squamous cell carcinoma (R)

Clinical signs of pharynx disorders

Signs of respiratory distress

Stridor, coughing, dyspnea, Gagging

Exacerbated by excitement, heat, stress, or exercise

Pharyngitis causes

trauma, bacterial & viral agents (as for nasal cavity), neoplasms, cysts, lymphoid hyperplasia

Lesions associated with pharyngitis

serous, catarrhal, suppurative, fibrinous, fibrinonecrotic, hemorrhagic or granulomatous inflammation

Pharyngeal Obstruction and Perforation

Intraluminal foreign bodies: medicament boluses, apples, or potatoes

can move down and obstruct the larynx and trachea

Sites of lodgement of FBs

Anywhere in the pharyngeal region

location and size determine the occurrence of dysphagia, regurgitation, dyspnea, or asphyxiation

Pharyngeal obstruction: Masses in the surrounding tissue

Neoplasms

thyroid gland, thymus, parathyroid glands

Pharyngeal Obstruction and Perforation: Nonspecific insults can cause lesions

perforation of the caudodorsal wall of the pharynx from the improper use of drenching or balling guns in sheep, cattle, and pigs

choking injury because of the use of collars in dogs and cats

shearing forces of bite wounds

Pharyngeal obstruction and perforation: Sequelae of trauma

Minimal: local edema and inflammation

Serious: complete luminal obstruction by exudate

Pharyngeal diverticulum in pigs: in the pharyngeal wall rostral and dorsal to the

esophageal entrance

barley awns may lodge in the diverticulum, inflammatory swelling that affects swallowing

The diverticular wall may be perforated by awns or drenching syringes,

exudate can extend down: the tissue planes between muscles of the neck, even into the mediastinum

Pharynx of the dog: trauma

trauma from chicken bones, sticks, and needles → pharyngeal abscessation

Dysfunction/Responses to Injury: esophagus

healing is relatively rapid → Normal epithelial turnover rate is 5 to 8 days

breach of the epithelial barrier resulting in ulceration (because of acid reflux or mechanical damage) → Can lead to circumferential scarring → Permanent narrowing of the lumen → predisposition to future episodes of obstruction

Esophagus: Portals of Entry/Pathways of Spread

Materials, caustic chemicals, some parasites, gastric reflux

thoracic cavity: penetration or obstruction by foreign objects

Iatrogenic puncture of the esophagus

Esophagus defense mechanisms

Stratified squamous epithelium: Keratinized in pigs, horses, and ruminants, Nonkeratinized in dogs and cats

Healing is relatively rapid

Muscularis: Striated in ruminants and dogs, Smooth in horses

Submucosal mucus glands: Present throughout the esophagus (pigs, dogs) or pharyngeal junction (cats, horses, ruminants)

Megaesophagus (esophageal ectasia)

dilation of the esophagus: insufficient, absent, or uncoordinated peristalsis in the mid- and cervical esophagus

Dogs, cats, cows, ferrets, horses, and New World camelids

Causes of megaesophagus

Innervation or denervation disorders

Partial physical obstructions and stenosis 2º secondary to: inflammatory diseases of esophageal musculature, persistence of the right aortic arch (PRRA)

Idiopathic (in aged camelids)

Congenital megaesophagus

Partial blockage of the lumen of the esophagus by a persistent right fourth aortic arch (PRAA) → vascular ring forms around the esophagus and trachea, preventing full dilation of the esophagus

Aorta, pulmonary artery, and ductus arteriosus form the ring

Image of congenital megaesophagus

Acquired megaesophagus (aka. esophageal achalasia)

failure of relaxation of the distal esophageal (cardiac) sphincter of the stomach obstruction and thus dilation occurs cranial to the stomach

But does not involve the cardiac sphincter

Causes of acquired megaesophagus

Idiopathic

Secondary to: Polymyositis, Esophagitis, Hypothyroidism

Myasthenia gravis (disorder of acetylcholine receptors of the neuromuscular junction)

Recurrent gastric dilation. Increased risk in dogs is seen in German shepherds, Golden retrievers, and Irish setters.

Clinical signs of megaesophagus

Regurgitation after ingestion of solid food → congenital megaesophagus is often recognized at weaning

Animals are thin, ± Aspiration pneumonia.

Radiographically: Esophagus is dilated anterior to the lesion and retains radiopaque dyes

Esophagus: neoplasia

Generally rare

Bracken fern (Pteridium aquilinum) consumption ± papilloma virus infection

Squamous cell carcinomas in cattle

Signs of neoplasia or tumors in the esophagus

Dysphagia, regurgitation, weight loss, dilation of the esophagus proximal to the mass

Tumors of the esophagus are occasionally palpable but are most often intraluminal rather than mural

Epithelial - Papillomas, and Squamous cell carcinomas → wide metastatic potential

Fibrosarcomas of dogs: often develop associated with Spirocerca lupi infestation

Leiomyoma, Lymphosarcoma

where does Choke (Esophageal obstruction) occur

mostly in anatomic locations in which the esophagus cannot fully expand

Dorsal to the larynx, cranial to the first rib at the thoracic inlet, base of the heart, diaphragmatic hiatus

If foreign bodies are lodged against the epithelium for longer than 2 days it leads to?

circumferential pressure necrosis of the esophageal mucosa strictures during healing

reflex regurgitation after ingestion of food → starvation or aspiration pneumonia

Choke initial signs

Hypersalivation (ptyalism), Coughing, Repeated attempts to swallow, Nasal discharge of feed material and saliva (This is a key indicator)

Choke progression of signs

Gagging retching, and Regurgitation, Dysphagia, Decreased Appetite and Weight Loss, Lethargy, Anxiety and Restlessness, Pain with Movement

Other possible signs of choke

Abdominal Distension, Bloat, Smacking/Licking Lips, Pawing at the Mouth or Face, Pacing/Restlessness.

Esophagus: erosion and ulcers causes

Reflux of stomach acid

Improper use of stomach tubes: linear scraping on the crests of the longitudinal folds of the esophageal mucosa

Foreign bodies, Infectious diseases, mucosal injury in other locations as well

Esophageal parasites: Spirocerca lupi of dogs pathogenesis

most pathogenic of the esophageal parasites

penetrate through the gastric mucosa → adventitia of arteries → abdominal aorta → caudal thoracic aorta → granuloma in the adventitia

passage forms between the esophageal lumen and the granuloma containing the parasite

Spirocerca lupi clinical signs

dysphagia, aortic aneurysms, hemothorax, and rarely esophageal fibrosarcomas or osteosarcomas

Chronic aortic granulomas: spondylosis deformans adjacent to the aortic granulomas

Esophagus: Hiatal hernia

Protrusion of the abdominal esophagus and cardia of the stomach through the diaphragm into the thoracic cavity

Inversion is generally into the esophageal lumen

can lead to gastroesophageal intussusception (sometimes)

Images of hiatal hernia