Introduction

Congenital lobar emphysema is a rare condition that has been described in both humans and dogs but in only one kitten.^1–3

The condition is characterized by abnormal overinflation of a lung lobe leading to compression of the remaining pulmonary parenchyma. Atelectasis of the normal residual lung usually causes dyspnea and hypoxia refractory to standard medical treatment. The overinflation of a lung lobe may be secondary to congenital or acquired causes. The most frequent causes reported are congenital, and they consist of anomalies of the bronchial cartilage or external compression on the bronchi, for example, caused by vascular anomalies reported in children, which leads to air trapping.^4–7

Various concomitant diseases have been reported in association with this condition in dogs and humans, such as pneumomediastinum, pneumothorax, and cardiac abnormalities.^2,7,8

This report documented a case of congenital pulmonary emphysema of the left cranial lung lobe in association with a type III hiatal hernia and complicated by secondary nutritional hyperparathyroidism in a kitten.

Case Report

A 2 mo old domestic shorthair kitten was referred to the University Veterinary Hospital, Department of Veterinary medical Sciences, University of Bologna for worsening respiratory distress of a 12 hr duration.

The kitten had a history of sneezing, epiphora, and a raw meat diet. More recently, the kitten had difficulties in walking after falling from a step in the house 1 wk earlier. At the time of presentation, the kitten showed inability to stand up, open-mouth breathing, severe tachypnea, and expiratory dyspnea. Chest auscultation revealed decreased pulmonary and heart sounds on the left side. Flow-by oxygen supplementation was started, with only minor improvement of the respiratory distress.

Venous blood gas analysis, a complete blood cell count and blood chemistry, thoracic radiographs, and ultrasound examinations were carried out. The blood gas analysis revealed moderate ionized hypocalcemia (1.04 mmol/L, range 1.13–1.38 mmol/L) and severe respiratory acidosis (pH 7.13, range 7.34–7.40; pCO₂ 79.5 mmol/L, range 32.7–44.7 mmol/L). The complete blood count revealed mild anemia (29.2% hematocrit, range 32.0–48.0%). The chemistry profile showed a decrease in creatinine (0.61 mg/dL, range 0.80–1.08 mg/dL) and total protein concentrations (5.05 g/dL, range 6.5–8.8 g/dL), and a mild increase in alkaline phosphatase concentration (170 U/L, range 20–140 U/L). Phosphorus was within the reference range (4.21, range 2.5–6.2 mg/dL). Thoracic radiographic examination showed a marked and diffuse hyperlucency of the left hemithorax associated with a decreased volume of the right lung. The heart was also shifted to the right. In the caudal mediastinum, a mass with soft-tissue/gas opacity appeared to be in continuity with the stomach. A severe and diffuse reduced radiopacity of the bones included in the radiographs was evident (Figure 1). Incomplete fractures of the left femur, both tibiae, and the right radius were also detected.

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The ultrasonographic examination of the thorax revealed the presence of the stomach in the caudal mediastinum. Based on diagnostic imaging results, a diagnosis of hiatal hernia associated with a congenital bullae pneumopathy or left lung lobar emphysema was made. The presence of ionized hypocalcemia associated with multiple skeletal abnormalities led to the suspicion of nutritional secondary hyperparathyroidism. This hypothesis was additionally corroborated by the description of the kitten’s diet (raw meat diet) provided by the owners.

A surgical approach was strongly advised because of the severe compression of the lungs and refractory dyspnea.

The kitten was started on fluid therapy with lactated Ringer’s solution^a (1 mg/kg/hr IV). After premedication with methadone^b (0.1 mg/kg intramuscularly [IM]), ketamine^c (1 mg/kg IM), and midazolam^d (0.1 mg/kg IM), anesthesia was induced with propofol^e administered IV to effect (up to 3 mg/kg) until endotracheal intubation was feasible and maintained with sevoflurane^f (1%) in pure oxygen. Intraoperative analgesia was provided with fentanyl^g (constant rate infusion 0.01 mg/kg/hr IV). Cephazoline^h (22 mg/kg IV) was administered as intraoperative antibiotic prophylaxis.

After surgical preparation of the abdomen and the thorax, a cranial celiotomy and caudal sternotomy were performed. During surgical exploration of the thorax, the left cranial lung lobe appeared abnormally inflated and emphysematous while the left caudal and the right lung lobes appeared atelectasic. The gastroesophageal junction, the fundus, and a portion of the body of the stomach were herniated through the esophageal hiatus into the caudal mediastinum (hiatal hernia type III) (Figure 2). A lobectomy of the left cranial lung lobe was performed with en bloc ligation of the hilum using nonabsorbable 3/0 sutureⁱ, and the lobe was transected with a sealing device ^j. After lobectomy, the other lung lobes gradually expanded. Repositioning of the stomach in the abdomen by gentle traction from the laparotomy was not possible, probably because of the solid contents of the stomach. After blunt dissection and enlargement of the diaphragmatic esophageal hiatus, retraction of the stomach into the abdominal cavity was performed. The incision of the diaphragm was sutured with simple interrupted sutures, using 3/0 absorbable sutures^k; hiatal plication was then performed after temporarily placing an oroesophageal tube (10 Fr) up to the stomach in order to guide the dimensioning of the new esophageal hiatus by horizontal mattress sutures using a 3/0 absorbable sutures^k. An esophagopexy was performed with absorbable simple interrupted sutures using 3/0 absorbable sutures^k. A left-side incisional gastropexy was performed with two rows of continuous absorbable sutures using a 3/0 absorbable sutures^k.

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A chest drain was applied^l on the right side, and the sternotomy was closed using a figure-of-eight pattern interrupted sutures with peristernal nonabsorbable 2/0 suturesⁱ.⁹ The laparotomy and the soft tissues incised for the sternotomy were routinely sutured.

In the postoperative period, the kitten received methadone^b (0.1 mg/kg IM q 4 hr) and meloxicam^m (0.05 mg/kg per os q 24 hr) for pain treatment, antimicrobial therapy (cephazoline^h, 22 mg/kg IV q 8 hr), and antacid therapy (omeprazoleⁿ 1 mg/kg per os q 24 hr). No dyspnea was evident, even if the respiration rate remained mildly increased for the first 3 days. However, after surgery, the kitten experienced recumbency, urine retention, and signs of diffuse pain during palpation of the muscle and bone of the limbs. These findings were considered related to the secondary nutritional hyperparathyroidism and worsening hypocalcemia the first postsurgical day (ionized calcium 0.99 mmol/L, range 1.13–1.38 mmol/L). Therefore, IV supplementation with 10% calcium gluconate^o was started (0.5 mL/kg IV bolus slowly for 20 min during continuous electrocardiogram monitoring, followed by a continuous rate infusion at 60 mg/kg/day for the next 24 hr). The clinical signs resolved, and calcium supplementation continued orally (calcium carbonate^p 60 mg/kg/day) in association with the introduction of a balanced commercial food for kittens. The kitten was managed with an indwelling urinary catheter^q with a closed urine collection system for 48 hr; it was removed as walking improved and spontaneous urination resumed. The kitten was sent home after 4 days of hospitalization with a plantigrade stance but no other significant clinical issues. Calcium supplementation and a balanced commercial food for kittens were continued at home, and the gait improved to normal in 1 wk.

Histological evaluation of the lung lobe removed revealed the presence of severe and diffuse lung alveolar emphysema, with variably sized cystic to bullous spaces formed by the rupture and confluence of contiguous alveolar septa. The peribronchial cartilage rings appeared to be reduced in number and were irregularly oriented. These microscopic features, associated with age and clinical findings, were consistent with a final diagnosis of congenital lobar emphysema.

At a 12 day follow-up, the kitten was in good clinical condition with no sign of dyspnea. At a 1 mo follow-up, the physical examination of the kitten was unremarkable. Ionized calcium was considered normal for the kitten’s age (1.4 mmol/L, range 1.13–1.38 mmol/L). Radiographs of the thorax showed normal bone opacity as well as a left shift of the heart shadow and a slight reduction in the caudal left lung radiolucency, compatible with the previous surgery. The sternum presented a moderate dorsal deviation between the third and fourth sternebrae; however, because of the normal respiratory pattern, no further investigation or treatment was proposed. At a 2 yr follow-up, the cat is still in good clinical condition without any abnormal respiratory signs.

Discussion

The present study described congenital lobar emphysema in a young kitten in association with type III hiatal hernia and secondary nutritional hyperparathyroidism. The association of lung lobe emphysema and hiatal hernia is novel in veterinary literature and might have worsened the respiratory signs and promoted acute patient decompensation. The surgical treatment consisting of lung lobectomy and reduction of the hernia led to the complete resolution of the breathing difficulties. Secondary nutritional hyperparathyroidism was an additional presenting complication of the case described and complicated the postoperative management of the kitten; however, it was successfully addressed with calcium supplementation and a balanced diet.

Congenital lobar emphysema is a rare condition that has been reported in one kitten as well as puppies and children.^{1,2,6,7,10–12} In milder cases diagnosed in adult humans, the disease is said to go unnoticed for some time and become evident during adult life.³

In the majority of the dogs and in the kitten diagnosed with this condition, the right middle lung lobe was affected.^1,2,8 On the contrary, in humans, congenital lobar emphysema mainly affects the left apical lung, and males are overrepresented.³ In the present report, the kitten was a male, and the left cranial lung lobe was affected; however, no hypotheses for sex predisposition and location of the disease have been formulated in the veterinary literature, probably because of the rarity of the disease.

Bronchial cartilage abnormalities and their subsequent collapse have been claimed to be the main causes of the disease.^1,2,8 Bronchial dysgenesis was also reported in an adult dog with lobar emphysema and in an adult cat.^10,15 In the present case, the histopathological findings disclosed abnormalities of the bronchial structures that could have caused progressive air entrapment, alveolar wall rupture, and confluence of the alveolar spaces. In addition to the young age of the kitten, all these abnormalities could have led to the diagnosis of congenital lobar emphysema.

The history of sneezing and ocular discharge some weeks before the clinical presentation with acute dyspnea could have raised the possibility of concurrent feline upper respiratory tract disease. The latter could have contributed to worsening the bronchial obstruction and to the overinflation of the lung lobe. However, no upper respiratory signs were evident at the time of presentation, and no specific diagnostic test was carried out to screen for the presence of any infectious pathogen. To the best of the authors’ knowledge, no correlation between feline respiratory tract disease and lobar emphysema has been formulated in the veterinary literature.

Pneumothorax, pneumomediastinum, and cardiac abnormalities have been described in association with lobar emphysema in the veterinary literature.^2,8 In the present case, a congenital hiatal hernia was present in association with the lobar emphysema. Such a combination of diseases has never been reported either in animals or in humans affected with lobar emphysema. Moreover, the overall clinical picture of the case herein described was complicated by concurrent secondary nutritional hyperparathyroidism.

Hiatal hernia could have been a concomitant disease of the kitten because multiple concurrent abnormalities have already been reported in cats with congenital diseases.^16,17 The breathing difficulties could have led to an increase in negative intrathoracic pressure, potentially worsening the stomach displacement through an excessively large hiatus. It is also possible that the dyspnea could have caused the hiatal hernia, because it is reported in cats with upper respiratory obstruction.¹⁸ Dyspnea could also have favored gastric distension with gas. All these options could have increased lung compression, decreased the patient’s respiratory capacity, and eventually promoted acute respiratory decompensation.

A double approach to the thorax and the abdomen for lung lobectomy and hiatal hernia reduction, respectively, was necessary to relieve the compression on the unaffected lung lobes and to allow repositioning of the stomach and the hiatal hernia. No precise guidelines are present in the veterinary literature regarding the surgical treatment of a hiatal hernia; however, the current recommendation for hiatal hernia repair in dogs and cats is the combination of hiatal plication, esophagopexy, and left-flank incisional gastropexy.^17–19 The reduction of the esophageal hiatus by hiatal plication is difficult to assess intraoperatively; therefore, the temporary application of the esophageal tube helps in assessing its dimensions and preventing excessive reduction. An endoscopic-assisted technique for hiatal plication was proposed by Pisoni et al. (2012)¹⁷ in an adult cat; however, the use of endoscopy was not possible in the present case because of the emergency situation together with the small size of the kitten.

The kitten made a good recovery in the postoperative period with no complications related to the surgical procedure; however, the inability to stand up and urinary retention were observed in the postoperative period. The urinary retention was attributed to possible inadequate pain control or to the previous ambulatory difficulties of the kitten. The latter, coupled with the documented ionized hypocalcemia and the multiple skeletal abnormalities (bone hypodensity and partial fractures), led to hypothesizing a diagnosis of secondary nutritional hyperparathyroidism. In fact, the kitten recovered well after the calcium supplementation and the introduction of a balanced commercial diet. To the authors’ knowledge, no correlation between lobar emphysema and secondary nutritional hyperparathyroidism is present in humans or veterinary literature.

The sternal deviation observed at a 1 mo radiographic check-up could be considered a mild pectus excavatum and could be a complication of the sternotomy performed on a very young kitten with secondary nutritional hyperparathyroidism. However, the kitten had no respiratory signs and remained in good clinical condition; no treatment was proposed.²⁰

Conclusion

Congenital lung lobe emphysema is a rare disease in the cat; however, it should be considered in the differential diagnosis in kittens or young cats with dyspnea. Moreover, if the disease is addressed in time, the surgical treatment may lead to a full recovery with a good long-term outcome.