MEGA-OESOPHAGUS IN CANINES & FELINES
Definition of Oesophagus—It is a hollow tubular muscular organ lined with mucous membrane of Alimentary canal connecting Oral cavity to Stomach of Vertebrates having peristaltic moment for passage of food .It is synonym as “Food Pipe”.
Definition of Mega- oesophagus—It is a disorder in monogastric vertebrates including Dogs characterised by oesophageal dilation & aperistalsis. Which is a syndrome of genetic idiopathic(common) or acquired idiopathic lesion involving defect in Vagal (10th Cranial Nerve)afferent Nerve intervention of oesophagus where Oesophagus size is increased for certain aetiology/disease resulting loss of its ability of peristaltic moment causing accumulation of food in Oesophagus.
Aetiology—
- Congenital idiopathic disorder—GSD,Labrader,Irish setter,Great Dane, Fox terror etc. breeds of Dogs & Siamese breed of Cat
- Acquired idiopathic disorder—It is a secondary sequel to diffuse neuro-muscular dysfunction
- Vagal afferent Nerve defective intervention in Oesophagus—causing oesophageal distension but Upper & lower Oesophageal spnictor muscle is unaffected.
- Dysautonomia—Autonomic nerve neuropathy resulting oesophageal hypomortility effected in Degenerative autonomic ganglia- usually in Cats
- Segmental diffuse hypomortility due to foreign body/stricture/vascular ring anomaly/oesophagities in oesophagus etc.
- Oesophageal hypomortility with oesophageal redundancy(no longer useful)—it is usually in Chinese Shar Peis –a breed of Dog having multifold skin with Grade Dane like face with medium stature
- Trauma to spinal chord or brain—dysfunctioning oesophageal contraction
- Toxins/poisoning
Symptoms(Clinical manifestation)—
- Regurgitation episode frequency & variability exist in post meal/post injection of food
- Puppies regurgitate post weaning to solid food
- Ptylation hypersalivation,Depression,anorexia,constipation,regugitation
- Physical examination—dry mm, pupilary dilation, prolapsed nictitating membrane(3rd eye lid), bradycardia,areflexive annus , buldging at base of neck , painful on touch etc.
- In chronic cases malnutrition, emaciation, weight loss
- Respiratory distress characterised by moist cough & dyspnea
- Hyperthermia indicates aspiratory infective pneumonia
- Muscle pain & stiff gait
- Polymyositis(increased serum creatinin level)
- Secondary to Lead(Pb) toxicity & Addition’s disease(Adrenal gland disorder resulting low Cortisol production( hyponatremea & hypokalemea) & hypotension due to stress or chronic infection)
Diagnosis—
- Symptom & anamnesis of regurgitation
- Radiography( X-Ray) of Cervical & Thoracic region –
- indicates Pneumo/hydro/ingesta filled dilated oesophagus
- Opaque Pulmonary Alveoli indicates aspiratory pneumonia
- Barium salt contrast Radiography indicates oesophageal dilation/ mechanical obstruction/ other oesophageal abnormalities
- VFSS Test—Video Fluoroscopic Swallow Study/Vagal Fluoroscopy Test– for detection of peristaltic moment in oesophagus
- Electromyogram—to detect nerve response of oesophagus & weak muscle response to nerve conduction
- Bio chemistry of Blood parameters including CBC(Complete Blood Count)
- Rapid Pinpoint pupil on application of 1% pilocarpine(diluted to 0.1%) eye lotion ( normal -45-60 minutes to contraction of pupil spnictor)
- Urine analysis– Proteinuria for systemic lupus erythematus condition for Spirocerca lupi
- Skin biopsy– systemic lupus erythematus condition for Spirocerca lupi
- Schirmer Tear test-reduced production of Tear
- Acetylcholine receptor antibody titre test/tensilon test /Atropine test—0.04 mg/Kg-S/C for ¼ to 1 hr to detect Bradycardia( decreased Heart Rate)—for acquired Mega oesophagus
- Oesophagoscopy—detect obstruction for neoplasia or reflux oesophagities
Treatment—
- Supportive & symptomatic with palliative treatment
- Small frequent meals from an upright standing position allowing passage of food to stomach by aid of gravitational force with less resistance
- Gruel ( liquid)or Bulky( semi solid) food depending on patient’s acceptability
- Gastrostomy tube –A tube used to pass on food bypassing Stomach( directly to stomach )
- Intubation—Passing food directly to stomach through oesophagus by help of an aseptic plastic tube
- Broad spectrum Antibiotic medication– for infection or aspiratory pneumonia – specifically amoxicillin + potassium Clavunate is drug of choice
- Smooth muscle prokinetic agents( no effect on striated muscle of oesophagus)—Clopramide—for dog(decrease oesophageal transit rate)/Cisapride—for Cat (relieve distal oesophageal motility hindrance ) drug—
- Re-evaluate animals after 1-2 months for progression
- Myasthenia gravis – detected by Acetylcholine receptor antibody titre test—Treat to improve muscle tonicity vide Pyridostigmine( Mestinon tab-60 mg tab available) @ 0.25-1 mg/Kg//orally/bid +Prednisolone @ 0.25-0.5 mg/Kg/orally/bid or S/C injection bid
- Systemic Lupus Erythematus(SLE)—-Prednisolone @ Prednisolone @ 0.25-0.5 mg/Kg/orally/bid or S/C injection bid
- Polymyositis/polymyopathy—(Diagnosed by Muscle biopsy)– Prednisolone @ Prednisolone @ 0.25-0.5 mg/Kg/orally/bid or S/C injection bid
- Botox treatment—(injecting food to lower part of Oesophagus)–Sidenafil(relieve pulmonary hypertension in Dog & Cat) –@ 0.5 – 3 (2.2-6.5)mg/Kg/orally/ tid
- Oesophageal neoplasis—Surgical extirpation/Radiation therapy/Chemo or in combination therapy as per necessity. In metastatic case chemo is must.
- Oesophageal stricture—Balloon dilation
- Foreign body—
- endoscopic retrieval(by biopsy forceps having cups to grasp small soft foreign body like cotton/piece of dress etc)
- Hard /pointed object—surgical resection
- Potato/Bone obstruction can be digested
- Lead poisoning ( Pb)—Chelated treatment with Calcium EDTA.
Prepared & presented by Dr.Keshaba Chandra Samantaray ,M. V. Sc. (Gynaecology), Gold Medallist, OUAT, Bhubaneswar, Retired-Joint Director, Frozen Semen Bank, Chiplima, Sambalpur, Govt. of Odisha.
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