RATTUS (Rat Thoracic Ultrasound): diagnosis of pneumothorax in pet rats

Introduction

Rat thoracic ultrasound (RATTUS) is a non-invasive, easy-to-perform method for the evaluation of the pleural space and lungs in pet rats. The aim of the article is to present species-specific differences in the sonographic diagnosis of pneumothorax (PTX) in pet rats.

Methods

In total, 158 client-owned pet rats were examined during the period from July 2023 to January 2024. PTX was diagnosed in 20 of the examined rats (13.25%, the age of the animals ranged from 2 months to 32 months (19.08 ± 6.93 months; mean ± SD) and their body weight ranged from 97 g to 885 g (461.27 ± 138.97 g; mean ± SD). Radiographic confirmation of PTX was performed in all these 20 rats, in the control group radiography was used to confirm that PTX was not present.

Results

The lung point and the barcode sign was found in 7/20 animals with sensitivity of 33.3% (95% CI, 0.16-0.59) and specificity of 100% (95% CI, 0.97-1.0). The abnormal curtain sign was found in 19/20 of animals with the sensitivity of 95% (95% CI, 0.73-0.99.7) and the specificity of 89% (95% CI, 0.82-0.93). The abnormalities in the substernal access were in 17/20 of animals with the sensitivity of 85% (95% CI, 0.61-0.96) and the specificity of 71% (95% CI, 0.62-0.78).

Discussion

In conclusion, RATTUS is a non-invasive method for the diagnosis of PTX in rats. Lung point and barcode sign are specific but not easily diagnosed signs. The curtain sign in RATTUS is not specific for PTX, as there are e.g. geriatric rats (rats older than 1,5 years) in which the abnormal curtain sign is visible without the presence of PTX. The presence of moderate to severe PTX can be assessed by the substernal approach based on the presence of cardiac displacement toward the collapsed lung lobe, and on evaluation of the lung inflation symmetry. This sign is not specific for PTX but in conjunction with other ultrasonic signs described makes the RATTUS a feasible tool for PTX diagnosis in rats.

Comparison of thoracic ultrasonography and thoracic radiography between healthy adult horses and horses with bacterial pneumonia using a novel, objective ultrasonographic scoring system

Background

Thoracic ultrasonography (TUS) is widely used in equine practice but comparison to radiography is limited in horses.

Objectives

To validate a novel, objective scoring system for TUS in adult horses and to compare ultrasonographic and radiographic findings.

Animals

13 healthy horses and 9 with confirmed bacterial pneumonia

Methods

Prospective study in which TUS and radiography were performed on healthy horses and those with bacterial pneumonia confirmed by clinical signs and results of transtracheal wash analysis. Ultrasonography was scored utilizing a novel scoring system evaluating number of comet tail lesions, the presence or absence of pleural effusion and/or pulmonary consolidation in each intercostal space. Eighteen horses had thoracic radiographs taken that were scored by a board-certified radiologist utilizing a previously described system. Total scores were recorded and compared between control and diseased patients.

Results/Findings

Ultrasonographic scores were significantly higher in the diseased group (median= 126) than in the control group (median = 20, p = 0.01). Receiver operating characteristics (ROC) analysis identified a sensitivity of 66.7% (95% CI 0.417–1) and specificity of 92.3% (95% CI 0.462–1) for the ability of ultrasonography to identify bacterial pneumonia utilizing a TUS score cutoff of 37.

Conclusions and clinical importance

TUS had moderate sensitivity and high specificity for identification of bacterial pneumonia in adult horses. TUS appears to be an acceptable stand-alone imaging modality for diagnosis of bacterial pneumonia in horses when radiography is not practical.

Pneumoperitoneum as an uncommon complication after an axillary laceration in a horse

Lacerations of the axillary region occur frequently in horses. Typical complications caused by entrapment of air in the wound during locomotion are subcutaneous emphysema, with consecutive pneumomediastinum and pneumothorax. In this case report, the clinical, radiographic and laboratory diagnosis and management of these complications after an axillary laceration that finally resulted in pneumoperitoneum are described. A 1-year-old Hannoveranian was presented with a pre-existing axillary laceration of unknown duration and subcutaneous emphysema in the surrounding tissue. Due to extensive tissue loss, attempts to adequately close the wound surgically and by packing with sterile dressing material were unsuccessful. Despite stall confinement and tying of the horse, subcutaneous emphysema was progressive and pneumomediastinum as well as pneumothorax was developed. These complications were monitored radiographically. On day 5 after admission, signs of air accumulation were detected on radiographs craniodorsally in the peritoneum and a pneumoperitoneum was diagnosed. Repeated thoracentesis with a teat cannula to gradually evacuate the thoracic cavity was used in combination with nasal oxygen insufflation to treat global respiratory insufficiency. Subcutaneous emphysema and all other complications resolved progressively and the horse was discharged from the hospital 21 days after admission when the axillary wound was adequately filled with granulation tissue. The wound healed fully 1 month later and the horse did not develop long-term complications within the following year. To the authors´ knowledge, the development of pneumoperitoneum including its radiographic monitoring following an axillary laceration has not been described in horses previously.

Respiratory Distress in the Adult and Foal

Respiratory distress in the horse and foal is an emergency. Managing equine respiratory distress in the field starts with appropriate assessment of the patient to determine whether the breathing obstruction stems from the upper or lower respiratory tract or is nonrespiratory in origin. From a thorough, but efficient, physical examination to point-of-care ultrasound and endoscopy, the veterinarian has many tools in the field to help diagnose the patient.

Comparison between thoracic ultrasonography and thoracic radiography for the detection of thoracic lesions in dairy calves using a two-stage Bayesian method

Infectious bronchopneumonia is a lower respiratory tract disease with major economic consequences in dairy calves. Thoracic radiography (TR) and thoracic ultrasonography (TUS) are two imaging diagnostic procedures available in bovine medicine for identifying thoracic lesions. However, no study has investigated whether one of these tests is superior to the other or if they provide comparable results for the detection of thoracic lesions in calves. The objective of this study was therefore to estimate and to compare the performances of TUS and TR for the detection of thoracic lesions in dairy calves. A prospective cross-sectional study was performed in a hospital setting. A total of 50 calves (≥7 days old; ≤100 kg; standing; pCO2 ≥ 53 mmHg; any reason of presentation) were enrolled. Every calf underwent TUS and TR. Only calves with thoracic lesions on TUS and/or TR were controlled by thoracic computed tomography (CT) (the gold standard). Calves without lesions were not controlled by CT. A two-stage Bayesian framework was used. The sensitivities (Se) and specificities (Sp) of both tests individually and used in series or parallel were estimated. The Se and Sp of TUS were 0.81 (95 % BCI (Bayesian Credible Interval): 0.65; 0.92) and 0.90 (95 % BCI: 0.81; 0.96), respectively. The Se and Sp of TR were 0.86 (95 % BCI: 0.62; 0.99) and 0.89 (95 % BCI: 0.67; 0.99), respectively. This study did not reveal any differences between both tests. Using TUS and TR in series was more specific than using both tests in parallel. The performances of TUS alone were not different from the performances of both tests in series or in parallel. In conclusion, TUS and TR were equivalent in detecting thoracic lesions in this study. Using TUS alone allowed an accurate detection of thoracic lesions in dairy calves. Further studies enrolling a larger sample (> 400 calves) and allowing adequate power to be achieved would be necessary to confirm these results.