Esophageal motility dysfunction in cats: a study of 44 cases

Mechanical ventilation in dogs and cats with tick paralysis

Respiratory failure from tick paralysis (TP) is an important cause of mortality in cats and dogs in Australia, occurring from a combination of respiratory muscle paralysis, upper respiratory tract obstruction and pulmonary disease. Patients may require positive-pressure ventilation in management of any combination of hypoxemia, hypoventilation or respiratory fatigue, but may also require airway management due to laryngeal paralysis. No single ventilation strategy is recommended due to the heterogenous disease presentations. Lung protective ventilation should be used in patients with pulmonary disease. Due to local and systemic effects of TP, patients are at higher risk of complications such as aspiration pneumonia and corneal ulceration and may have additional intravenous fluid and nutritional considerations. Treatment with hyperimmune serum is associated with improved outcomes. Prognosis is considered good with documented survival to discharge (STD) of 52.6-77% for animals with TP ventilated with lung disease and 90.5% for animals without lung disease. Median reported duration of ventilation for TP ranges from 23 to 48 h (range 3 h-10 days). The severity of individual neuromuscular signs and the presence of associated conditions such as aspiration pneumonia and laryngeal paralysis may necessitate longer periods of mechanical ventilation. This review aims to summarize the current recommendations regarding indications, management and prognosis of cats and dogs undergoing MV for TP and to identify areas for future research.

Surgical treatment of a distal oesophageal stricture by mucosal radial incision and dilation in a kitten with secondary megaoesophagus

Case summary

A 7-month-old intact female Maine Coon cat was presented with a 2-month history of regurgitations. Contrast radiographic and endoscopic examinations revealed a diffuse megaoesophagus secondary to a severe lower oesophageal stricture. An epiphrenic diverticulum was noted. Endoscopic balloon dilation was unsuccessful. Gastrotomy was thus performed in order to incise the oesophageal wall radially along the stricture site, and then to dilate the stricture. A diameter of 20 mm was reached. With the aim of preventing stricture recurrence, submucosal injections of triamcinolone acetonide were performed. An 18 Fr oesophagogastric feeding tube was placed and a left gastropexy was performed in order to exert some traction on the gastroesophageal junction, with the aim of reducing the oesophageal diverticulum. Twelve months postoperatively, clinical signs had completely resolved and follow-up radiographs revealed marked improvement of the oesophageal dilatation.

Relevance and novel information

Lower oesophageal strictures should be considered when evaluating regurgitations or megaoesophagus in a kitten. Surgical mucosal radial incision is a therapeutic option in cases of lower oesophageal stricture refractory to balloon dilation, and can lead to a marked improvement of clinical signs and of the oesophagus diameter leading to clinical success.

Intermittent Gastroesophageal Intussusception in a Kitten Resolved with a Percutaneous Gastropexy

Gastroesophageal intussusception is a rare pathology characterized by an acute or intermittent invagination of the stomach into the lumen caudal to the thoracic esophagus, the pathogenesis is not well understood, although it is likely multifactorial. The mortality is high, associated with a late diagnosis and a rapid deterioration. A 4-month-old male domestic shorthair kitten presented for evaluation of intermittent respiratory distress and abdominal discomfort with two weeks of evolution. Based on clinical history, clinical sings and imaging studies a diagnosis of intermittent gastroesophageal intussusception was established. The reduction of the intussusception was performed with endoscopy maneuvers and with medical and nutritional management for some days, but this failed and finally was reduced with a percutaneous gastropexy tube to prevent recurrence with a good long-term outcome. Gastroesophageal intussusception in cats is associated with megaesophagus or hiatal hernia, and should be considered as a differential diagnosis in patients with chronic vomiting, regurgitation or respiratory disease. Survey and contrasted thoracic radiographs can be used to identify gross anatomical abnormalities, but the definitive diagnosis should be made by esophagogastroscopy with the possibility of reducing the intussusception. The use of percutaneous gastropexy provides other possible option to conventional surgery for the management of this pathology in cats.

Recovery of normal esophageal function in a kitten with diffuse megaesophagus and an occult lower esophageal stricture

An 8-week-old male domestic shorthair was presented to the Internal Medicine Service at North Carolina State University for regurgitation. Radiographic diagnosis of generalized esophageal dilation and failure of esophageal peristalsis were compatible with diagnosis of congenital megaesophagus. Endoscopic examination of the esophagus revealed a fibrous stricture just orad to the lower esophageal sphincter. Conservative management to increase the body condition and size of the kitten consisted of feeding through a gastrostomy tube, during which time the esophagus regained normal peristaltic function, the stricture orifice widened in size and successful balloon dilatation of the stricture was performed. Esophageal endoscopy should be considered to rule out a stricture near the lower esophageal sphincter in kittens with radiographic findings suggestive of congenital megaesophagus. Management of such kittens by means of gastrostomy tube feeding may be associated with a return of normal esophageal motility and widening of the esophageal stricture, and facilitate subsequent success of interventional dilation of the esophageal stricture.

Contrast videofluoroscopic assessment of dysphagic cats

The diagnostic utility of contrast-enhanced videofluoroscopic esophagography in dysphagic cats has been rarely studied relative to dogs. Current literature regarding feline dysphagia typically consists of individual case reports or small case series. This retrospective study analyzed the imaging findings in 11 cats undergoing 15 videofluoroscopic swallow studies. Hiatal hernia (n = 5), esophageal stricture (n = 3), and esophageal dysmotility (n = 7) were the most common diagnoses (some cats having more than 1 diagnosis) in dysphagic cats that underwent videofluoroscopic swallow studies. Esophageal dysmotility appeared to be associated with a higher percentage of swallows from which no peristaltic waves were generated. Oropharyngeal and cricopharyngeal causes of dysphagia were not identified in any cat and quantitative assessment of the swallowing reflex (pharyngeal constriction ratio = 0.17 ± 0.09; time to maximum pharyngeal contraction = 0.13 ± 0.02 s; time to proximal esophageal sphincter opening = 0.07 ± 0.02 s; time to proximal esophageal sphincter closed = 0.23 ± 0.05 s; time to opening of the epiglottis = 0.27 ± 0.04 s) was similar to quantitative swallowing parameters previously reported in healthy dogs. In conclusion, videofluoroscopy is a diagnostic tool that can identify esophageal abnormalities that are not readily apparent on survey radiographs. Limitations include the potential need for multiple studies, and the possibility of poor compliance in the feline patient. Results of this study are intended to help veterinarians define a prioritized differential diagnosis list for dysphagic cats.

Gastrointestinal endoscopy in the cat

Practical relevance:

Endoscopic examination of the feline gastrointestinal (GI) tract is a minimally invasive method for obtaining biopsy samples of the GI mucosa, which is often necessary for a diagnosis of chronic GI diseases. In addition endoscopy has several therapeutic indications including foreign body retrieval, oesophageal stricture dilation and placement of a percutaneous gastrostomy tube.

Clinical challenges:

Initially, practitioners must learn the subtle manipulations necessary to efficiently guide the endoscope through the GI tract to obtain biopsy samples of high diagnostic quality, and develop skills for implementing interventional procedures (eg, foreign body removal). Another challenge in mastering GI endoscopy is the ability to recognise normal from abnormal, which requires many years of practice and experience. Endoscopy is a diagnostic and interventional procedure that should be performed only in conjunction with a thorough history, physical examination, appropriate laboratory evaluation, and radiographic and/or ultrasonographic imaging.

Audience:

This review is intended to familiarize both the general and referral practitioner with GI endoscopy as a minimally invasive diagnostic and therapeutic intervention for the feline patient.

Evidence base:

The guidance contained within this article is based on a combination of the published literature, the authors’ personal experience and the experience of colleagues.

Oesophageal disease in 33 cats

A retrospective study was performed to investigate the frequency of identification and characteristics of oesophageal disease in cats, including assessment of the utility of diagnostic techniques and clinical outcome. Thirty-three cats met the inclusion criteria, giving an in-clinic frequency of 33/2894 (approximately 1%) of feline referral cases. Vomiting and/or regurgitation were the most common presenting signs described, although a number of cats (6/33) showed neither. Useful diagnostic modalities included plain radiography, fluoroscopy, barium radiography and endoscopy. A wide range of diseases was reported including congenital disease, oesophagitis, foreign body obstruction, neoplasia, extraluminal compression and hypomotility disorder. Five of six cats with acquired oesophageal strictures had recently received doxycycline per os.

Imaging findings in 11 cats with feline dysautonomia

Dysautonomia is caused by degeneration of the autonomic ganglia. Failure of the autonomic system affecting the gastrointestinal and urinary tracts can cause oesophageal distension and/or dysfunction, gastric and bowel distension and hypomotility, and urinary bladder distension. The aim of this retrospective study was to describe diagnostic imaging findings in cats with dysautonomia. Common findings were megaoesophagus and/or oesophageal dysfunction, gastric distension and signs of intestinal ileus. Associated aspiration pneumonia and megacolon appeared less commonly. Although diagnostic imaging findings are not specific for this disease, if findings in multiple systems are detected, along with consistent clinical signs and neurological deficits, dysautonomia should be considered among the differential diagnosis.

Esophageal Diverticulum Associated With a Trichobezoar in a Cat

A 9-year-old, castrated male, domestic longhaired cat was evaluated for persistent regurgitation over the previous month. The cat had presented 9 months earlier and was diagnosed with esophageal obstruction secondary to a trichobezoar. The trichobezoar had been removed endoscopically, and the cat was subsequently fed a canned prescription diet. The owners noted only infrequent regurgitation over the following 9 months. After signs recurred, contrast radiography with fluoroscopy revealed an esophageal diverticulum at the thoracic inlet, with an ovoid filling defect. Decreased esophageal motility was noted distal to the diverticulum. Esophagoscopy confirmed the presence of a trichobezoar within an esophageal diverticulum. Following removal of the trichobezoar and therapy to prevent trichobezoar formation, the cat did well for 2 months until it died suddenly with signs of hyperventilation and open-mouth breathing.

Sedative and hypnotic effects of combined administration of metoclopramide and ketamine in chickens

Metoclopramide is a dopamine receptor antagonist used in animals as both an antiemetic and a gastroprokinetic agent. In chickens, the drug causes central nervous system depression. The authors examined the potential sedative and hypnotic effects of metoclopramide when administered in combination with the anesthetic agent ketamine in 1-3-week-old chicks. Concomitant administration of metoclopramide and ketamine markedly reduced the median effective doses (ED50s) of both drugs for the induction of sedation and sleep in the chicks. The results suggest potential therapeutic applications of the metoclopramide-ketamine combination as a restraining agent in avian species not intended for human consumption.

Idiopathic megaoesophagus and intermittent gastro-oesophageal intussusception in a cat

An eight-month-old domestic shorthair cat was presented with chronic vomiting for three months, with an acute increase in frequency during the past two days. A diagnosis of megaoesophagus was made by chest radiography. Diagnostic work-up for megaoesophagus was performed. A gastro-oesophageal intussusception was identified during endoscopy. Medical and nutritional therapy was instituted with a good response to the treatment.

Metoclopramide-induced central nervous system depression in the chicken

Background

Metoclopramide is a dopamine D2-receptor antagonist used as an antiemetic and gastroprokinetic agent in man and animals. The drug causes sedation as a side effect in man. Such a sedative action of metoclopramide has not been documented in the chicken as the drug is not used clinically in this species. The present study examines the central nervous system depressant effects of metoclopramide in 7–14 days old broiler chicks.

Results

Injection of metoclopramide at 50, 100 and 200 mg/kg, subcutaneously (s.c.) induced sedation in the chicks in a dose dependent manner. The chicks manifested, within 3.6–19 minutes of metoclopramide injection, signs of sedation characterized by drooping of the head and wings, closed eyelids, reduced motility and decreased distress calls. The duration of sedation ranged between 37.2 to 163.4 minutes. Metoclopramide at 100 and 200 mg/kg induced, within 12.2 and 6.2 minutes, sleep (loss of righting reflex) for 43.8 and 158.6 minutes, respectively. The median effective doses of metoclopramide for induction of sedation and sleep in the chicks were 11 and 53 mg/kg, s.c., respectively. Lower doses of metoclopramide (5 and 10 mg/kg, s.c.) significantly decreased the open-field activity of the chicks and increased the durations of their tonic immobility. All treated-chicks recovered from the central nervous system depressant effect of metoclopramide without any observable adverse effects.

Conclusion

The data suggest that metoclopramide induces central nervous system depression in chicks, and the drug could have potential clinical applications as a sedative-hypnotic agent in avian species not intended for human consumptions.

Esophagitis and esophageal strictures

Esophagitis and esophageal strictures are important causes of esophageal disease in dogs and cats. Clinical suspicion is created when the clinician recognizes the clinical signs suggestive of esophageal disease and accounts for historical information and physical examination findings. Once suspected, the diagnosis of esophagitis and esophageal strictures is a fairly simple one in most cases. Although the benefit of diminishing secretion of gastric acid in patients with esophagitis is unquestioned, other questions regarding adjunctive medical treatments, such as sucralfate and glucocorticoids for dogs and cats with esophagitis, have not been answered through appropriate clinical studies. Esophageal strictures are readily treated with balloon dilation or esophageal bougienage, and clients can expect most patients to become functional, although dietary change may be necessary.

Structural and functional basis for the long QT syndrome: relevance to veterinary patients

Long QT syndrome (LQTS) is a condition characterized by prolongation of ventricular repolarization and is manifested clinically by lengthening of the QT interval on the surface ECG. Whereas inherited forms of LQTS associated with mutations in the genes that encode ion channel proteins are identified only in humans, the acquired form of LQTS occurs in humans and companion animal species. Often, acquired LQTS is associated with drug-induced block of the cardiac K+ current designated I(Kr). However, not all drugs that induce potentially fatal ventricular arrhythmias antagonize I(Kr), and not all drugs that block I(Kr), are associated with ventricular arrhythmias. In clinical practice, the extent of QT interval prolongation and risk of ventricular arrhythmia associated with antagonism of I(Kr) are modulated by pharmacokinetic and pharmacodynamic variables. Veterinarians can influence some of the potential risk factors (eg, drug dosage, route of drug administration, presence or absence of concurrent drug therapy, and patient electrolyte status) but not all (eg, patient gender/genetic background). Veterinarians need to be aware of the potential for acquired LQTS during therapy with drugs identified as blockers of HERG channels and I(Kr).