Diagnostic outcome of contrast videofluoroscopic swallowing studies in 216 dysphagic dogs

Determining the anatomic and functional origin for dysphagia is critical for development of an appropriate therapeutic plan and determination of the prognosis. The purpose of this retrospective study was to report the quantitative and qualitative outcome of contrast videofluoroscopic swallowing studies in a large cohort of dysphagic dogs presenting to a tertiary veterinary care hospital. The videofluoroscopic swallowing studies were reviewed to generate values for pharyngeal constriction ratio, timing of swallowing events (maximum pharyngeal contraction, opening of upper esophageal sphincter, closing of upper esophageal sphincter, and reopening of epiglottis), type of esophageal peristalsis generated, and esophageal transit time. One or more anatomic locations for origin of dysphagia were assigned (pharyngeal, cricopharyngeal, esophageal (primary motility disorder), other esophageal (stricture, vascular ring anomaly, mass), lower esophageal sphincter/hiatus. Sixty‐one of 216 studies (28%) were deemed unremarkable. Twenty‐seven of 216 dogs (13%) had pharyngeal dysphagia, 17/216 dogs (8%) had cricopharyngeal dysphagia, 98/216 dogs (45%) had dysphagia secondary to esophageal dysmotility, 19/216 dogs (9%) had dysphagia secondary to focal esophageal disorders, and 97/216 dogs (45%) had dysphagia of lower esophageal sphincter/hiatus origin. Multiple abnormalities were present in 82/216 (38%) dogs. Elevated pharyngeal constriction ratio was associated with pharyngeal, cricopharyngeal, and esophageal motility disorders, delayed upper esophageal sphincter opening was associated with cricopharyngeal disorders, a lower percentage of primary esophageal peristaltic waves was associated with cricopharyngeal, pharyngeal, or primary esophageal motility disorders. In conclusion, videofluoroscopic swallowing studies was pivotal in the diagnosis of dysphagia with 155/216 (72%) dogs receiving a final diagnosis.     

Effects of Body Positioning on Swallowing and Esophageal Transit in Healthy Dogs

Background: Contrast videofluoroscopy is the imaging technique of choice for evaluating dysphagic dogs. In people, body position alters the outcome of videofluoroscopic assessment of swallowing.
Hypothesis/Objective: That esophageal transit in dogs, as measured by a barium esophagram, is not affected by body position.
Animals: Healthy dogs ( n = 15).
Methods: Interventional, experimental study. A restraint device was built to facilitate imaging of dogs in sternal recumbancy. Each dog underwent videofluoroscopy during swallowing of liquid barium and barium-soaked kibble in sternal and lateral recumbancy. Timing of swallowing, pharyngeal constriction ratio, esophageal transit time, and number of esophageal peristaltic waves were compared among body positions.
Results: Transit time in the cervical esophagus (cm/s) was significantly delayed when dogs were in lateral recumbency for both liquid (2.58 ± 1.98 versus 7.23 ± 3.11; P = .001) and kibble (4.44 ± 2.02 versus 8.92 ± 4.80; P = .002). In lateral recumbency, 52 ± 22% of liquid and 73 ± 23% of kibble swallows stimulated primary esophageal peristalsis. In sternal recumbency, 77 ± 24% of liquid ( P = .01 versus lateral) and 89 ± 16% of kibble ( P = .01 versus lateral) swallows stimulated primary esophageal peristalsis. Other variables were not significantly different.
Conclusions and Clinical Importance: Lateral body positioning significantly increases cervical esophageal transit time and affects the type of peristaltic wave generated by a swallow.     

Oropharyngeal dysphagias in the dog: A cinefluorographic analysis of experimentally induced and spontaneously occurring swallowing disorders

Cinefluorography and videofluorography were used to record and analyze functional swallowing deficits of 12 dogs with spontaneously occurring oropharyngeal dysphagias and six experimental dogs with selected neurectomies. Ten of the 12 dogs had dysphagias affecting the cricopharyngeal stage of the oropharyngeal phase of swallowing. Two dogs had mixed oropharyngeal dysphagias. Clinical signs of cricopharyngeal dysphagia could not be differentiated from those of dysphagias due to pharyngeal or mixed oropharyngeal deficits. Signs of cricopharyngeal dysphagia consisted of: 1) repeated attempts to swallow; 2) excessive head movement; 3) dropping food from the mouth after unsuccessful swallowing attempts; 4) reingestion of dropped food. Nine of these dogs had cinefluorographic evidence of asynchrony between the normal pharyngeal contraction and relaxation, and subsequent cricopharyngeal relaxation and contraction. Only one dog demonstrated a consistent cricopharyngeal non-opening (achalasia). Seven of the dogs responded dramatically to cricopharyngeal myotomy. Two dogs with mixed oropharyngeal dysphagias had poor contractility of the pharyngeal muscles in addition to cricopharyngeal dysphagia. Clinical and cinefluorographic evaluation following cricopharyngeal myotomy of one dog verified exacerbation of functional deficits due to the iatrogenic cricopharyngeal chalasia. Esophagopharyngeal reflux accentuated the contrast medium retention in the pharynx and laryngotracheal aspiration. The need was stressed for careful differentiation between cricopharyngeal dysphagia and dysphagias involving the pharyngeal stage. Four experimental dogs with selective bilateral neurectomies of branches of the glossopharyngeal (IX) and vagus (X) nerves were evaluated clinically and cinefluorographically in an attempt to identify the pathogenesis of cricopharyngeal dysphagia. The variable results in the four dogs and the observed recovery in two dogs suggested that peripheral motor nerve deficits are not a major cause of cricopharyngeal dysphagia. Glossopharyngeal neurectomy in two dogs induced a profound functional disorder involving the pharyngeal and cricopharyngeal stages and the esophageal phase of swallowing. This would support a new hypothesis that the glossopharyngeal nerve is sensory to the esophagus as well as the pharynx, and may play a major role in disorders of the pharynx, upper esophageal sphincter, and esophagus, including congenital or acquired megaesophagus.     

L-thyroxine responsive cricopharyngeal achalasia associated with hypothyroidism in a dog

An eight-year-old, male boxer dog was presented with a one-month history of hindlimb weakness followed by compulsive ineffective drinking, dysphagia, regurgitation and nasal reflux during drinking. A neurological examination revealed weakness and conscious proprioception deficits in both hindlimbs with normal spinal reflexes. The dog's swallowing function was examined by fluoroscopy. This showed normal prehension of the barium paste, bolus formation and contraction of the pharyngeal muscle, but no opening of the upper oesophageal sphincter was detected. A serum thyroid stimulating hormone level of 0.402 ng/dl and serum total T4 of 0-01 microg/dl were determined. The dog fully recovered one month after L-thyroxine therapy. The association found between cricopharyngeal achalasia and hypothyroidism suggests that hypothyroidism should be included in the list of differential diagnoses for dogs with cricopharyngeal achalasia.     

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.     

Normal Swallowing in the Dog: A Cineradiographic Study

Normal dog swallowing dynamics were analyzed and correlated with specific structures. There were oropharyngeal, esophageal, and gastroesophageal phases. The oropharyngeal phase was characterized by food prehension and bolus formation (oral stage), reflex pharyngeal peristalsis (pharyngeal stage), and reflex cricopharyngeal sphincter relaxation (cricopharyngeal stage). The esophageal phase was characterized by primary peristalsis initiated by the oropharyngeal phase and secondary peristalsis which occurred in response to mechanical stimuli from a bolus in the esophagus. There was a post-peristalsis refractory period during which new peristalsis would not occur. Repeated rapid swallowing would, therefore, result in accumulation of ingesta in the esophagus. The gastroesophageal phase occurred when a bolus passed through the gastroesophageal junction, an area which serves as a lower esophageal sphincter. Gastroesophageal reflux was observed as a normal, infrequent event followed by rapid esophageal clearance. Low doses of tranquilizers had no significant influence on swallowing function. The differences observed between sternal and lateral recumbent postures related only to the rate of food consumption which, in turn, influenced esophageal motor response and inhibited gastroesophageal closure. These differences did not adversely affect the autonomous phases of swallowing.     

Cricopharyngeal achalasia in a dog

A 4-month-old, female terrier-poodle cross was presented with a chronic history of dysphagia. Fluoroscopic swallowing studies localized the problem to the upper esophageal sphincter. A diagnosis of cricopharyngeal achalasia was made. After cricopharyngeal and thyropharyngeal myectomy, the dog was able to eat soft food without difficulty.     

An anatomical and clinical review of cricopharyngeal achalasia in the dog

Cricopharyngeal achalasia is a rare cause of dysphagia in the dog. However it must be differentiated from other causes of dysphagia as it is treatable with surgery. It is a disruption of the cricopharyngeal phase of the oropharyngeal phase of deglutition. There appears to be an incoordination in the swallowing process between the relaxation of the rostral, middle pharyngeal muscles and the caudal pharyngeal muscles. It is seen as a primary condition in young animals presenting soon after weaning onto solid food. The dogs appear clinically healthy unless there is secondary aspiration pneumonia or emaciation. These dogs may present as respiratory emergencies and require intensive support and treatment prior to corrective surgery. The diagnosis is made on videofluoroscopy. The condition carries a good prognosis for cure with surgical myectomy of the cricopharyngeal muscle and the thyropharyngeal muscle, which make up the upper oesophageal sphincter. Temporary relief prior to surgery can be achieved by injection of the cricopharyngeal muscle with botulism toxin. Surgical treatment for dysphagia secondary to an underlying neurological, neuromuscular or pharyngeal weakness carries a guarded prognosis and will make aspiration pneumonia worse.     

Resolution of dysphagia following cricopharyngeal myectomy in six young dogs

Six young dogs were presented with a history of dysphagia and nasal regurgitation since birth. Following cranial nerve examination and assessment of swallowing with fluoroscopy, a diagnosis of cricopharyngeal achalasia was made in each case. In four dogs, concomitant aspiration pneumonia was present. Sectioning and removal of part of the cricopharyngeal muscle resulted in immediate and continued resolution of all signs of dysphagia and nasal regurgitation over follow-up periods of two to eight years. Postoperative complications were not seen in any case. In five of the six dogs, the cricopharyngeal muscle was approached laterally, a technique not previously described.     

OROPHARYNGEAE DYSPHAGIAS IN THE DOG: A CINEFLUOROGRAPHIC ANALYSIS OF EXPERIMENTALLY INDUCED AND SPONTANEOUSLY OCCURRING SWALLOWING DISORDERS

Cinefluorography and videoflurography were used to record and analyze the functional swallowing deficits of nine dogs with spontaneous oropharyngeal swallowing problems. Based on the clinical and radiographic signs observed in one dog with experimentally induced bilateral hypoglossal palsy and comparison with cinefluorograms of normal dogs, the nine spontaneous dysphagias were divided into five oral dysphagias and four pharyngeal dysphagias. Dogs with oral dysphagias had problems with tongue control and in prehending and transporting food and fluid to the oropharynx. On cinefluorograms, a poor closure of the oral egress led to the loss of contrast medium from the mouth, and a weak tongue-thrust action caused retention of contrast medium in the oropharynx. The clinical and radiographic signs could be duplicated by hypoglossal neurectomy. In contrast to the pharyngeal dysphagias, aspiration pneumonia was noticeably absent in oral dysphagias. The dogs with pharyngeal dysphagia had severe difficulties in transporting the food from the oropharynx to the laryngopharynx owing to a poor contractility of the pharyngeal muscles. The latter resulted in contrast medium retention in the pharynx and laryngotracheal aspiration. The need was stressed for a careful differentiation between oral and pharyngeal dysphagias on one hand, and cricopharyngeal dysphagias on the other hand. In oral dysphagias, cricopharyngeal myotomy appeared of no use. In pharyngeal dysphagias, cricopharyngeal myotomy severely aggravated the clinical signs by causing a cricopharyngeal chalasia.     

Contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the swallowing process in dogs

The separate contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the innervation of the pharyngeal muscles were studied first in 10 canine cadavers by dissection of the pharyngeal plexus and the pharyngeal muscles. In 10 other dogs, the parent trunks and 1st division of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve were electrically stimulated. The evoked stimulation potentials were recorded from the stylopharyngeal, hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. One of the parent trunks was then transected, and the effects on the swallowing process were observed clinically and by contrast videofluorography. Denervation potentials resulting from nerve transection were recorded in the soft palate, the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. The pharyngeal plexus was composed of branches originating from the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve. In most dogs, the pharyngeal muscles and the soft palate were innervated ipsilaterally by both nerves. The swallowing process was more severely disturbed after bilateral transection of the pharyngeal branch of the vagus nerve than after bilateral transection of the glossopharyngeal nerve.     

EFFECT OF BOLUS SIZE ON DEGLUTITION AND ESOPHAGEAL TRANSIT IN HEALTHY DOGS

Contrast videofluoroscopy is the gold standard procedure for evaluating dysphagia in humans, but quantitative measures vary depending on bolus size and consistency. We hypothesized that quantitative measures made during videofluoroscopy of swallowing in dogs would differ between bolus sizes and consistencies. Ten healthy adult dogs were enrolled a prospective, crossover experimental study and underwent contrast videofluoroscopy while swallowing liquid (5, 10, and 15 ml) and canned food (3, 8, and 12 g) boluses. Maximum pharyngeal contraction occurred significantly later with medium solid boluses than with medium liquid boluses, with a mean difference of 0.021 s (adjusted P = 0.042). Upper esophageal sphincter opening occurred significantly earlier with large solid boluses than with medium solid boluses, with a mean difference of 0.018 s (adjusted P = 0.025). Thoracic esophageal transit time was significantly longer with small solid boluses than with small liquid boluses, with a mean difference of 0.68 s (adjusted P = 0.004). Odds of primary esophageal peristalsis occurring were significantly (18.5 times) higher with large solid vs. large liquid boluses (adjusted P = 0.031). No other statistical comparisons reached significance. Based on these results, we recommend a standardized approach to videofluoscopy in dogs with determination of quantitative measures using medium liquid and soft food boluses to minimize effects of size. Furthermore, we conclude that measurements made on liquid swallows should not be directly compared to measurements made on soft food boluses.     

GASTRIC EMPTYING IN THE NORMAL DOG A Contrast Radiographic Technique

A total of 22 radiographic studies was made to determine comparative gastric emptying times of two different solid test meals (intact kibble food and ground kibble food mixed with barium sulfate suspension) in four mature (15-26 months) normal Beagle dogs under controlled conditions. Complete gastric emptying times of the intact kibble and ground kibble meals of a given dose (8 g/kg of dog food plus 5-7 ml/kg of the contrast agent) ranged from five to ten hours (7.6 ± 1.98 hours with intact kibble meal and 7.0 ± 1.86 hours with ground kibble meal). Feeding a halfdose of ground kibble meal (4 g/kg of dog food plus 3.5 ml/kg of the contrast agent) resulted in complete gastric emptying times of four to six hours (4.7 ± 0.67 hours). Individual dogs had repeatable gastric emptying times although the times varied among different dogs.     

Upper gastrointestinal examinations: a radiographic study of clinically normal beagle puppies

A total of 24 upper gastrointestinal examinations were performed on four weanling beagle puppies over six weeks, using liquid barium (10 ml/kg bodyweight of 60 per cent w/v barium sulphate suspension] and barium food (8 g/kg of crushed kibble dog food and 7 ml/kg bodyweight of 60 per cent w/v barium sulphate suspension) as contrast media. The radiographic appearance was similar to that noted in adult dogs except for the consistent location of the pylorus on or near the midline. Duodenal pseudoulcers were seen more often with liquid barium and the caecal shadows were identified more often with the longer examination time with barium food. The stomach of the puppies appeared to have discriminatory emptying function; that is, semi-solid food was emptied from the stomach at a slower rate (210 to 450 minutes) than liquid (60 to 90 minutes). Solid meals emptied faster in puppies than in adult dogs. Dosages of 13 to 15 mg/kg bodyweight for the liquid barium examination and 14 g of ground kibble and 16 ml of barium sulphate suspension per m² of body surface area for the barium food examination are suggested as more appropriate for contrast studies in puppies.     

Inheritance of cricopharyngeal dysfunction in Golden Retrievers

OBJECTIVE: To characterize a genetic component to cricopharyngeal dysfunction (CD) in Golden Retrievers. ANIMALS: 117 dogs. PROCEDURE: The CD phenotype was determined by videofluoroscopy, and dogs were classified as affected if the upper esophageal sphincter (UES) did not open, if there were morphologic abnormalities of the UES, or if opening of the UES was delayed for > or = 6 videofluoroscopic frames (0.2 seconds) after closure of the epiglottis. All survey radiographic and videofluoroscopic studies were reviewed by the same radiologist. RESULTS: Of the 117 dogs (47 males and 70 females) with a CD phenotype determined via videofluoroscopy, 21 dogs (18.0%) had abnormalities of the UES (affected). Of these 21 dogs, 9 were males (19.1% of all males) and 12 were females (17.1% of all females). The heritability of CD in a threshold model was estimated as 0.61, which established that CD could be passed from parent to offspring. Results of complex segregation analysis suggested that a single recessive allele of large effect contributed to the expression of this disease in Golden Retrievers. CONCLUSIONS AND CLINICAL RELEVANCE: The determination that CD is inherited in Golden Retrievers is an important step in providing information for veterinarians attending dogs with this disorder. Breeders also require this information to make informed breeding decisions.     

Dysphagia as the primary clinical abnormality in two dogs with inflammatory myopathy

Two adult Boxers were evaluated because of chronic dysphagia of several years' duration. Serum creatine kinase activity was high in both dogs, but other hematologic or serum biochemical abnormalities were not detected. Esophagraphy revealed abnormalities of the cricopharyngeal phase of swallowing in both dogs, and electromyography of the pharyngeal and laryngeal muscles revealed complex repetitive discharges, positive sharp waves, and fibrillation potentials characteristic of primary myopathy or neuropathy. Because of the severity of their condition, both dogs were euthanatized. Histologically, mixed-cell infiltrates were seen in sections of the masseter and thyropharyngeal muscles. Results of indirect immunofluorescence staining for proteins associated with dystrophic myopathy were unremarkable, except for decreased staining for integrin alpha7. A diagnosis of chronic inflammatory myopathy was made. The clinical importance of reduced staining for integrin alpha7 could not be determined but was considered to be a result of the myopathy.     

Dysphagia in Bouviers associated with muscular dystrophy; evaluation of 24 cases

Twenty-four Bouviers with dysphagia were examined between October 1986 and October 1988. The type of dysphagia was characterised by the results from the clinical examination, the videofluorographic examination and the electromyographic recordings from the oral, pharyngeal, and esophageal muscles. Electromyography indicated neurogenic as well as myogenic causes of dysphagia. Tissues from 10 dogs were available for histopathologic examination. In nine dogs there was a progressive muscular degeneration of the pharyngeal and/or esophageal muscles, resembling muscular dystrophy. In two of these dogs the same abnormalities were also noticed in the masseter and temporalis muscles and in the intrinsic laryngeal muscles. In one dog small areas with hyalin degeneration and fragmentation of muscle fibres were found in the cricopharyngeal muscle. No abnormalities in nerve tissue were found. Muscular dystrophy is a hereditary disease. The mode of transmission in these Bouviers is not yet known.     

Equine esophageal pressure profile

Esophageal motility was studied in 5 healthy adult horses, using a 4 side-hole catheter assembly continuously perfused with distilled water. Resting pressure and maximal pressures generated during swallowing were measured over the whole length of the esophagus (mean +/- S means = 132.7 +/- 2.31 cm). Four functionally distinct regions of the esophagus were demonstrated: cranial esophageal sphincter, caudal esophageal sphincter, and "fast" and "slow" regions in the body of the esophagus. The resting pressure of the cranial and caudal esophageal sphincters were 171.1 +/- 20.45 (x +/- S means) and 10.5 +/- 0.61 (x +/- S means) mm of Hg, respectively. The maximal pressure of the "fast" and the "slow" esophageal regions and caudal esophageal sphincter were 63.1 +/- 3.75 (x +/- S means), 71.9 +/- 3.65 (x +/- S means), and 63.1 +/- 2.60 (x +/- S means) mm of Hg, respectively. The length of each region and duration of pressure events were quantitated, establishing an equine esophageal pressure profile.     

Cricopharyngeal achalasia in Cocker Spaniels

Cricopharyngeal achalasia is described in three Cocker Spaniel puppies, two being male littermates, the other a bitch from a litter comprising two bitches and two dogs. From 3 weeks of age, solid food was consistently regurgitated, while some fluids were returned via the nares. Diagnosis was made on fluoroscopic demonstration of failure of relaxation of the cricopharyngeal sphincter dorsal to the larynx. Myotomy of the cricopharyngeus muscle and partial section of the thyropharyngeus and oesophageal musculature resulted in considerable improvement. One animal with aspiration pneumonia remained with an occasional cough and all three animals were liable occasionally to regurgitate if eating fast.     

Endoscopic observations on the deglutition reflex in the horse.

Cine-endoscopy was used to study the deglutition reflex in 2 apparently normal horses. Closure of the nasopharyngeal sphincter was brought about by a lowering of the pharyngeal roof and an elevation of the soft palate caudal to the pharyngeal ostia of the auditory tubes. The medial cartilages of the ostia were not directly involved in bringing about closure of the sphincter. It is postulated that the opening of the ostia of the auditory tubes is brought about during deglutition by the combined action of the palatopharyngeus, pterygopharyngeus and tensor veli palatini muscles.