Suspected Fluoroquinolone-Induced Exacerbation of Myasthenia Gravis in Dogs.

Acquired myasthenia gravis (MG) in dogs can present with focal or generalized weakness and is diagnosed by the presence of circulating antibodies to the acetylcholine receptor. Megaesophagus is the most common focal form of MG. Although exacerbation of MG has been associated with the use of fluoroquinolones in humans, it has not been previously described in dogs. The medical records of 46 dogs diagnosed with MG based on acetylcholine receptor antibody testing from 1997 to 2021 were retrospectively evaluated to identify any dogs who demonstrated exacerbation of MG after the administration of a fluoroquinolone. Exacerbation of MG, from focal to generalized, occurred in a median of 4.5 days after initiation of fluoroquinolone therapy in six dogs. In addition, one dog with generalized MG and megaesophagus developed pyridostigmine resistance subsequent to fluoroquinolone therapy. Marked improvement in generalized weakness was reported 36 hr after discontinuation of fluoroquinolone therapy alone in one dog and in combination with pyridostigmine in two dogs. Fluoroquinolone therapy was never stopped in three dogs who were euthanized because of severe weakness and one dog who died of respiratory arrest.

Management and outcomes of 13 dogs treated with a modified Heller myotomy and Dor fundoplication for lower esophageal sphincter achalasia-like syndrome.

OBJECTIVE: To report the management and outcomes of dogs treated for lower esophageal sphincter achalasia-like syndrome (LES-AS) with modified Heller myotomy, Dor fundoplication, and with the use of a temporary gastrostomy tube. STUDY DESIGN: Retrospective. SAMPLE POPULATION: Thirteen client-owned dogs. METHODS: Medical records and a client survey were used to assess frequency of vomiting/regurgitation, quality of life (QoL), bodyweight, and feeding modifications at the following time points: prior to referral, postoperatively from discharge to first recheck (4-6 weeks), and from first recheck to survey (48 months). Postoperative and gastrostomy tube complications were surveyed and recorded. Pretreatment and 4-6 weeks postoperative videofluoroscopic swallow studies (VFSS) were compared. Two-sided t-tests were used to compare outcomes between survey time points. RESULTS: Postoperative VFSS scores (available in 9 dogs) improved over preoperative scores in 6 dogs, and 12/13 dogs survived to discharge. One dog was euthanized 3 days postoperatively due to aspiration pneumonia. Postoperative gastrostomy tube complications occurred in half of the dogs that survived to discharge. According to the owners, scores assigned to vomiting/regurgitation improved by 180% (P = .004), QoL by 100% (P = .004), and bodyweight by 63% (P = .035). CONCLUSION: Modified Heller myotomy with Dor fundoplication and the use of a temporary gastrostomy tube improved clinical signs and owners' perceived quality of life in half of the dogs treated for LES-AS in our clinical setting. Oral sildenafil therapy discontinued postoperatively suggests that surgery was equally efficacious. CLINICAL SIGNIFICANCE: Modified Heller myotomy with Dor fundoplication and temporary gastrostomy tube is a treatment option with potentially sustained benefits for dogs that have LES-AS.

Congenital idiopathic megaesophagus in the German shepherd dog is a sex-differentiated trait and is associated with an intronic variable number tandem repeat in Melanin-Concentrating Hormone Receptor 2.

Congenital idiopathic megaesophagus (CIM) is a gastrointestinal (GI) motility disorder of dogs in which reduced peristaltic activity and dilation of the esophagus prevent the normal transport of food into the stomach. Affected puppies regurgitate meals and water, fail to thrive, and experience complications such as aspiration pneumonia that may necessitate euthanasia. The German shepherd dog (GSD) has the highest disease incidence, indicative of a genetic predisposition. Here, we discover that male GSDs are twice as likely to be affected as females and show that the sex bias is independent of body size. We propose that female endogenous factors (e.g., estrogen) are protective via their role in promoting relaxation of the sphincter between the esophagus and stomach, facilitating food passage. A genome-wide association study for CIM revealed an association on canine chromosome 12 (P-val = 3.12x10-13), with the lead SNPs located upstream or within Melanin-Concentrating Hormone Receptor 2 (MCHR2), a compelling positional candidate gene having a role in appetite, weight, and GI motility. Within the first intron of MCHR2, we identified a 33 bp variable number tandem repeat (VNTR) containing a consensus binding sequence for the T-box family of transcription factors. Across dogs and wolves, the major allele includes two copies of the repeat, whereas the predominant alleles in GSDs have one or three copies. The single-copy allele is strongly associated with CIM (P-val = 1.32x10-17), with homozygosity for this allele posing the most significant risk. Our findings suggest that the number of T-box protein binding motifs may correlate with MCHR2 expression and that an imbalance of melanin-concentrating hormone plays a role in CIM. We describe herein the first genetic factors identified in CIM: sex and a major locus on chromosome 12, which together predict disease state in the GSD with greater than 75% accuracy.

Aberrant right subclavian artery in a dog - case report / [Ectopia de artéria subclávia direita em cão - relato de caso]

The brachiocephalic trunk and the left subclavian artery originate from the aortic arch, and both supply blood to the head, neck, and thoracic limbs. Anatomical variations, such as an aberrant right subclavian artery, are congenital conditions rarely observed in dogs, Thus, the objective of the present report was to describe a case of aberrant right subclavian artery in a 9-year-old Dalmatian. However, this anomaly was a finding in which the patient was asymptomatic during its 9 years of life and only at this age did he exhibit signs including sialorrhea, vomiting, hyporexia, and noisy deglutition. Blood count, biochemical profile, and thoracic radiography led to a diagnosis of megaesophagus and aspiration pneumonia. Despite the recommended treatment, the patient did not respond well; as such, the owner elected to euthanize the animal. On necropsy, the right subclavian artery originated directly from the aortic arch, followed a route from left to right dorsally to the esophagus, and then formed an impression of the vascular path over the muscular wall of the esophagus. The esophagus, in turn, exhibited a flaccid wall and dilation in the caudal portion to the vascular path made by the ectopic position of the right subclavian artery.(AU)

O tronco braquiocefálico e a artéria subclávia esquerda emergem do arco aórtico e são responsáveis por fazerem o suprimento sanguíneo para cabeça, pescoço e membros torácicos. Variações anatômicas, como a ectopia da artéria subclávia direita, são alterações congênitas raramente encontradas em cães, cujas alterações do sistema digestivo acontecem em pacientes recém-desmamados e não em adultos. Assim, o objetivo deste relato é descrever um caso de ectopia da artéria subclávia direita em uma cadela, Dálmata, de nove anos de idade. No entanto, essa anomalia foi um achado do qual o paciente foi assintomático durante os nove anos de vida e somente com essa idade apresentou sinais como sialorreia, vômito, hiporexia e deglutição ruidosa. O hemograma e os perfis bioquímicos, associados à radiografia torácica, levaram a um diagnóstico de megaesôfago e pneumonia aspirativa. Mesmo seguindo o tratamento recomendado, houve piora clínica do quadro e o animal foi submetido à eutanásia. À macroscopia, a artéria subclávia direita originava-se direto do arco aórtico, fazia um percurso da esquerda para a direita dorsalmente ao esôfago e, então, formava uma impressão do trajeto vascular sobre a parede muscular do esôfago. O esôfago, por sua vez, apresentava parede flácida e dilatação na porção caudal ao trajeto vascular feito pela posição ectópica da artéria subclávia direita.(AU)

Distal esophageal sphincter achalasia in a Labrador retriever dog with polypoid gastric mucosal hyperplasia and pyloric stenosis.

An 11-year-old, neutered female, Labrador retriever dog was presented with a history of intractable vomiting, regurgitation, and coughing. Computed tomography (CT) imaging identified marked hypertrophy of the distal esophagus with a suspicion of distal esophageal achalasia, based on the observation of a "bird beak" appearance. This was later confirmed on a fluoroscopic swallow study. Marked hypertrophy of the gastric pylorus was also identified on CT imaging, and polypoid gastric mucosal hyperplasia was diagnosed based on the gross endoscopic appearance combined with gastric histopathology. Secondary aspiration pneumonia was diagnosed based on the results of CT imaging, bronchoscopy and bronchoalveolar lavage fluid analysis. Medical therapy alone failed to elicit any significant improvement, but clinical resolution was achieved following surgical intervention comprising Ventral Heller myotomy, Dor's fundoplication, and pyloroplasty.

Achalasie du sphincter oesophagien distal chez un chien de race Labrador avec hyperplasie polypoïde de la muqueuse gastrique et sténose du pylore. Une femelle Labrador stérilisée âgée de 11 ans fut présentée avec une histoire de vomissements intraitables, de régurgitation et de toux. Un examen par tomodensitométrie (CT) identifia une hypertrophie marquée de l'oesophage distal avec un doute d'achalasie oesophagienne distale, sur la base de l'observation d'une apparence en « bec d'oiseau ¼. Ceci fut ultérieurement confirmé par examen fluoroscopique. Une hypertrophie marquée du pylore gastrique fut également identifiée lors de l'examen par CT, et une hyperplasie polypoïde de la muqueuse gastrique fut diagnostiquée sur la base de l'apparence macroscopique lors de l'endoscopie combinée avec l'examen histopathologique de la muqueuse gastrique. Une pneumonie par aspiration secondaire fut diagnostiquée basée sur les résultats du CT, de la bronchoscopie et de l'analyse du liquide de lavage broncho-alvéolaire. Une thérapie médicale seule ne parvint pas à éliciter une amélioration significative, mais une résolution clinique fut obtenue à la suite d'une intervention chirurgicale comprenant une myotomie ventrale de Heller, une fundoplicature de Dor, et une pyloroplastie.(Traduit par Dr Serge Messier).

Clinical features and prognosis of canine megaesophagus in Japan.

Megaesophagus (ME) is a common esophageal disease in dogs and the prognosis is generally poor, especially with aspiration pneumonia (AP). We retrospectively investigated the clinical features and prognosis of canine ME in Japan. Twenty-eight dogs were included in this study, with the Miniature Dachshund breed being significantly overrepresented (odds ratio: 4.33). Most cases (21 of 28) were diagnosed as idiopathic ME and Myasthenia gravis was the most common cause of secondary ME. The overall median survival time (MST) was not reached and the 3-month survival rate was 85.7%. Ten dogs were diagnosed with AP, at least once during the study period, and the MST of ME dogs with AP was 114 days. The survival time overall and even with AP, was notably more prolonged compared to the previous studies. We hypothesized that treatment for canine ME could prolong the survival time, even in those with both ME and AP.

Aberrant right subclavian artery causing megaoesophagus in three cats.

Three entire, domestic, shorthair male cats (age range: 3 months to 5 years) were referred because of regurgitation. Megaoesophagus attributable to aberrant right subclavian artery, originating from the aorta at the level of the fourth intercostal space, was diagnosed in all cats using thoracic radiography and CT angiography. One cat had concurrent patent ductus arteriosus with a normal aortic arch. Three-dimensional volume-rendered CT images were used to assess the malformations and to plan surgery for the treatment of the vascular anomalies. Different surgical approaches were used in the two kittens. The third cat was not operated. CT angiography is well suited for preoperative planning in cats with aberrant right subclavian artery alone or in combination with other vascular anomalies.

Barium sulphate aspiration pneumonia in a cat with megaesophagus and dextroposition of the aortic arch: case report / Pneumonia aspirativa por sulfato de barrio em gato com megaesôfago e destroposição de arco da aorta: relato de caso

A six-month-old female cat suffered aspiration of an abundant amount of barium sulfate during a radiographic procedure for the diagnosis of megaesophagus. Latero-lateral contrast radiography revealed severe dilation of the thoracic esophagus cranial to the base of the heart. Persistence of the right aortic arch was suspected and later confirmed during corrective surgery. Accumulation of barium sulfate, used as a contrast agent, was clearly observed in the lumen of the bronchi, bronchioles, and alveoli in the radiographic image. Days after the surgery, the animal developed severe respiratory distress, which resulted in death. Cytology results and histology analysis using polarized light demonstrated that the lumen of bronchi, bronchioles, and alveoli exhibited evident histiocytic infiltration with cytoplasm filled by abundant amorphous refractive granular material consistent with barium sulfate. In this report, we describe the anatomical, cytological, histopathological (using polarized light), and x-ray findings of a case of barium sulfate aspiration pneumonia in a cat resulting from the use of this contrast medium for the diagnosis of megaesophagus secondary to persistent right aortic arch.(AU)

Uma gata de seis meses aspirou grande quantidade de sulfato de bário durante procedimento radiográfico para diagnóstico de megaesôfago. Contraste radiográfico látero-lateral revelou dilatação de esôfago torácico até a base do coração. Persistência do arco aórtico direito foi confirmada durante cirurgia corretiva. Acúmulo de sulfato de bário, utilizado como agente de contraste, foi observado no lúmen de brônquios, bronquíolos e alvéolos à imagem radiográfica. Dias após a cirurgia o animal desenvolveu insuficiência respiratória grave e evoluiu para óbito. Resultado de citologia e histologia utilizado luz polarizada demonstrou que lúmen de brônquios, bronquíolos e alvéolos mostraram infiltração histológica com citoplasma cheio de material refratário granular amorfo compatível com sulfato de bário. Nesse relatório, descrevemos achados anatômicos, citológicos, histopatológicos e radiográficos de um caso de pneumonia aspirativa em gata resultante do uso desse meio de contraste para diagnóstico de megaesôfago secundário a persistência do arco aórtico direito.(AU)

Upper esophageal incompetence in five horses after prosthetic laryngoplasty.

OBJECTIVE: To describe a complication observed endoscopically in horses after prosthetic laryngoplasty (LP). STUDY DESIGN: Case series. ANIMALS: Horses (n = 5) that had previous LP. METHODS: Four horses had endoscopic examination as part of a larger prospective study and had saliva emanating from their upper esophageal opening. One other horse was referred with clinical signs of severe upper esophageal obstruction 2 months after LP. RESULTS: Four horses were observed to have saliva emanating from their upper esophageal opening during endoscopic examination 21-58 months after LP. Esophageal reflux was noted endoscopically at rest (n = 1) and during exercise (4). All 5 horses were reported to cough postoperatively, and 2 horses coughed severely when eating. On necropsy, the horse referred with signs of esophageal obstruction had dilation of the proximal esophagus associated with food impaction and had fibrosis and thickening of the left cricopharyngeus and thyropharyngeus muscles. CONCLUSIONS: Iatrogenic damage to the caudal pharyngeal constrictor muscles, the intrinsic musculature of the upper esophagus, or their innervation, or damage to the peri-esophageal fascia or esophageal adventitia may cause upper esophageal incompetence in horses after LP.

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.

Megaesophagus in Friesian horses associated with muscular hypertrophy of the caudal esophagus.

Friesian horses have a perceived high rate of congenital or hereditary diseases, including megaesophagus, that may lead to choke and death. A retrospective study was performed to determine the prevalence and pathologic characteristics of esophageal disease in 852 horses, including 17 Friesians, that had been necropsied over a 6-year period at the Diagnostic Center for Population and Animal Health. Forty-two horses had grossly described esophageal lesions (25 muscular hypertrophy, 7 hemorrhage, 6 megaesophagus, 4 erosion/ulceration, 3 obstruction, 2 tears, 2 secondary neoplasms, 2 lymphoid patches, 1 thin wall, 1 esophagitis). Some of these lesions occurred concurrently in the same horse. Ten of these horses died or were euthanatized because of severe esophageal disease (6 megaesophagus causing tears in 2 horses, 3 esophageal obstruction with food bolus, and 1 esophagitis). All 6 horses with megaesophagus were Friesians. No cause for megaesophagus was noted in the necropsy reports; however, 5 of these 6 Friesians had marked caudal esophageal muscular hypertrophy (wall thickness: 1.9 ± 0.3 cm). Microscopic review of the esophagus of these Friesians confirmed smooth muscle hypertrophy, with no obvious fibrosis, degeneration, or loss of myenteric plexi. Unlike the Friesians, the 4 non-Friesian horses with severe esophageal disease had esophageal obstruction with an intraluminal food bolus or severe esophagitis. None had caudal esophageal muscular hypertrophy. It is concluded that in comparison to other horse breeds, Friesians have a higher prevalence of severe esophageal disease, specifically megaesophagus, that is commonly associated with marked caudal muscular hypertrophy.

[Megaesophagus in the dog and cat]. / Megaösophagus bei Hund und Katze.

Megaesophagus is a disorder of the esophagus characterized by diffuse dilation and decreased peristalsis. It is classified into congenital and acquired forms. Gastrointestinal, endocrine, immune-mediated, neuromuscular, paraneoplastic, and toxic disorders have been associated with acquired megaesophagus. Common clinical signs of megaesophagus are regurgitation, weight loss, coughing, and halitosis. Most cases of megaesophagus can be diagnosed using thoracic radiography; however, diagnosing the underlying cause requires a thorough history and additional diagnostics. The treatment, management, and prognosis of megaesophagus vary greatly depending on the underlying cause.

Persistent regurgitation in four dogs with caudal esophageal neoplasia.

Esophageal neoplasia is an uncommon, but important, consideration for acute and chronic regurgitation and megaesophagus in dogs. The diagnosis can be challenging, and treatment options are often limited. This case series describes four dogs with regurgitation secondary to caudal esophageal masses. All dogs presented with regurgitation, and three of the four dogs had radiographically apparent megaesophagus. In all dogs, ancillary diagnostics revealed the presence of a caudal esophageal mass resulting in esophageal obstruction, and all mass lesions were histopathologically confirmed to be neoplastic. Treatment responses were variable, with one dog still alive 37 mo postdiagnosis at the time of manuscript preparation.

Megaesophagus.

Megaesophagus is a disorder of the esophagus characterized by diffuse dilation and decreased peristalsis. It is classified into congenital and acquired forms. Gastrointestinal, endocrine, immune-mediated, neuromuscular, paraneoplastic, and toxic disorders have been associated with acquired megaesophagus. Common clinical signs of megaesophagus are regurgitation, weight loss, coughing, and halitosis. Most cases of megaesophagus can be diagnosed using thoracic radiography; however, diagnosing the underlying cause requires a thorough history and additional diagnostics. The treatment, management, and prognosis of megaesophagus vary greatly depending on the underlying cause.

Nasopharyngeal stenosis with concurrent hiatal hernia and megaesophagus in an 8-year-old cat.

A case of nasopharyngeal stenosis with secondary hiatal hernia is described. An 8-year-old castrated male domestic shorthair cat was referred for a chronic upper respiratory problem and presumptive vomiting. Despite conservative management by the primary care veterinarian, the cat's condition progressed. The cat was presented to an emergency facility prior to referral to a specialty hospital. On presentation, inspiratory stridor was evident. Thoracic radiography revealed a hiatal hernia. Computed tomography indicated pharyngeal edema and probable nasopharyngeal stenosis. Endoscopy confirmed the presence of nasopharyngeal stenosis consistent with either stricture or choanal atresia. Balloon dilation of the choana was performed. The hiatal hernia regressed spontaneously post-resolution of the nasopharyngeal stenosis. The cat remained asymptomatic at recheck 3 months later.

Hypertrophic osteopathy and megaoesophagus in a cat.

A case of hypertrophic osteopathy in a stray cat is reported. It was not known how long periosteal proliferation had been present prior to the time of first presentation. A few months later, megaoesophagus became apparent. Computer tomography was performed at least 18 months after periosteal proliferation had first become evident, but an underlying neoplasia was not identifed in association with the hypertrophic osteopathy. The hypertrophic osteopathy and the megaoesophagus were both successfully medically managed, and the cat continued to do well 33 months after the hypertrophic osteopathy was first evident.

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.

Megaesophagus in a 6-month-old cat secondary to a nasopharyngeal polyp.

A 6-month-old male domestic shorthair cat was presented for a 3-month history of dysphagia and upper respiratory signs. The cat was diagnosed with a generalized megaesophagus secondary to a large nasopharyngeal polyp that extended into the cervical esophagus. The polyp was removed by traction and a left ventral bulla osteotomy was performed to remove the polyp base. The cat's clinical signs resolved and follow-up radiographs 14 days after surgery revealed resolution of the megaesophagus. To the authors' knowledge, this is the first report of resolution of megaesophagus after removal of a nasopharyngeal polyp in a cat.