Clinical features of canine pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis

The echocardiographic pulmonary to left atrial ratio: A noninvasive variable for the hemodynamic classification of pulmonary hypertension in dogs

BACKGROUND

Hemodynamic classification of pulmonary hypertension (PH) has important clinical implications. However, only a few echocardiographic variables have been used to hemodynamically classify PH in dogs.

OBJECTIVE

To evaluate the echocardiographic pulmonary to left atrial ratio index (ePLAR) in dogs with PH.

ANIMALS

Forty-six dogs with intermediate to high probability of PH.

METHODS

Cross-sectional study. Variables were compared between dogs with precapillary PH [PrePH (n = 24)] vs postcapillary PH [PostPH (n = 22)], and with combined PH [CombPH (n = 14)] vs isolated PH [IsoPH (n = 8)] using the t-, Mann-Whitney, Pearson's Chi, or Fisher's exact test. The receiver operating characteristic curve and Youden index were used to identify the optimal ePLAR cutoff value to differentiate among the groups, intraclass correlation coefficients (ICC) were used to determine the reliability of measurements.

RESULTS

The mean (SD) ePLAR of the PrePH was higher than that of the PostPH group [0.36 (0.13) vs 0.26 (0.09), respectively; P = .005]. The median (interquartile range) ePLAR of the CombPH was higher than that of the IsoPH subgroup [0.29 (0.24-0.38), vs 0.20 (0.16-0.23), respectively; P = .001]. The best cutoff value of ePLAR for identifying IsoPH was <0.245 [AUC at cutoff point = 0.86; sensitivity (95% confidence interval [CI]) = 0.71 (0.47-0.95); specificity (95% CI) = 1 (0.76-1)]. The ICC analysis indicated a high degree of reliability.

CONCLUSIONS AND CLINICAL IMPORTANCE

ePLAR can be considered a valid noninvasive variable to hemodynamically classify PH in dogs with an intermediate to high probability of PH. Assessment of ePLAR can be useful in the therapeutic management of PH in dogs.

Retrospective analysis of dogs and cats with a mixed form of pulmonary hypertension and suspected pulmonary capillary hemangiomatosis in comparison to animals with predomination of precapillary pulmonary hypertension

Background

Pulmonary capillary hemangiomatosis (PCH) is an idiopathic disease with the anomalous proliferation of a small capillary-like vessel in the pulmonary tissue, which can lead to a severe form of PH. There are only several cases of PCH described in veterinary literature: 27 cases in dogs and 2 cases in cats. In veterinary medicine, PH is mostly recognized as a consequence of left heart failure as a progression of the postcapillary PH to the precapillary form. PCH is mostly described as a primary disease, but resistant postcapillary PH with the high possibility of pulmonary edema raises speculation that PCH could be a secondary malformation to the left heart disease.

Aim

Discover the features associated with the shift between left- and right-sided heart disease in the context of PH development.

Methods

Retrospective analysis of materials from cats and dogs with histological markers of PCH (sPCH) versus those with right heart failure (RHF).

Results

Animals with histological and immunohistochemistry markers of PCH had a previous history of disease with left heart volume overload. There were no differences between the groups in radiography and gross pathology. Histologically, pulmonary fibrosis and arteriopathy could be found in RHF; in sPCH-a duplication of capillaries in alveolar septa and bizarre proliferation in surrounding structures.

Conclusion

PCH could be a secondary pattern of vascular remodeling due to volume overload.

Animals in Respiratory Research

The respiratory barrier, a thin epithelial barrier that separates the interior of the human body from the environment, is easily damaged by toxicants, and chronic respiratory diseases are common. It also allows the permeation of drugs for topical treatment. Animal experimentation is used to train medical technicians, evaluate toxicants, and develop inhaled formulations. Species differences in the architecture of the respiratory tract explain why some species are better at predicting human toxicity than others. Some species are useful as disease models. This review describes the anatomical differences between the human and mammalian lungs and lists the characteristics of currently used mammalian models for the most relevant chronic respiratory diseases (asthma, chronic obstructive pulmonary disease, cystic fibrosis, pulmonary hypertension, pulmonary fibrosis, and tuberculosis). The generation of animal models is not easy because they do not develop these diseases spontaneously. Mouse models are common, but other species are more appropriate for some diseases. Zebrafish and fruit flies can help study immunological aspects. It is expected that combinations of in silico, in vitro, and in vivo (mammalian and invertebrate) models will be used in the future for drug development.

Feline pulmonary hypertension: are we overlooking an important comorbidity?

Pulmonary hypertension (PH) is a potential complication in many disease states, yet it has been largely overlooked in feline medicine. Recently, increased awareness of potential underlying causes has led to a wider understanding of the disease process in humans, with a focus on tailoring therapy to include specific treatment of the underlying etiology. Most of these treatments are not yet available in veterinary medicine, but as they move from the human to the veterinary field, it would be beneficial to better understand the forms of PH encountered in different species. Recently, diagnosis and classification of PH in dogs has been the focus of an American College of Veterinary Internal Medicine consensus statement, yet this condition has received little attention in cats. It is therefore our intention to raise awareness of this condition in cats and to propose a classification system for the types of PH seen in feline patients. As new medications are developed for the treatment of PH, it is important to recognize which forms of PH are seen in feline patients and understand the etiology of the disease. There are many reports of PH (or suspected PH based on echocardiographic assessment) in cats. In this review, we highlight the large number of conditions, and different etiologies, that are associated with PH. Improving understanding of this condition will bring us closer to being able to investigate the benefits of potential new diagnostics and therapies as they become available.

Ventilator-Assisted Inspiratory and Expiratory Breath-Hold Thoracic Computed Tomographic Scans Can Detect Dynamic and Static Airway Collapse in Dogs with Limited Agreement with Tracheobronchoscopy

Airway collapse (AC) in dogs includes a tracheal collapse, mainstem and lobar bronchial collapse, and bronchomalacia (i.e., segmental/subsegmental bronchial collapse). The clinical presentation of AC may overlap with non-collapsible airway disease (NCAD) or another non-lower airway respiratory disease (NLARD). This study determined whether paired inspiratory (I)/expiratory (E)-breath-hold computed tomography (I/E-BH CT) can detect a static and dynamic AC in dogs with spontaneous respiratory disease and it compared the CT-derived metrics of the AC to the tracheobronchoscopy metrics. The CT-acquired I and E diameter and cross-sectional area (CSA) for the trachea, mainstem and lobar bronchi in dogs with an AC (n = 16), NCAD (16), and NLARD (19) served for a dynamic percent of the airway narrowing (%AN) calculation. A scoring system assessed the bronchomalacia. The circularity was calculated for each airway. The results were compared to the tracheobronchoscopy collapse grading. In the dogs with an AC, the %AN was larger for the trachea, right mainstem bronchus and right middle lobar bronchus when they were compared to the dogs with NCAD and NLARD. Flattening was only identified for the trachea of the AC dogs. The agreement between the CT and tracheobronchoscopy scores was 20% from trachea to the lobar bronchi and 47% for the segmental/subsegmental bronchi. Paired I/E-BH CT can detect static and dynamic AC with limited agreement with the tracheobronchoscopy metrics. Independent scoring systems that are tailored to the clinical manifestations of functional impairments are needed.

Survival characteristics and prognostic importance of echocardiographic measurements of right heart size and function in dogs with pulmonary hypertension

BACKGROUND

The clinical relevance of echocardiographic measurements of right heart size and function in dogs with pulmonary hypertension (PH) is unknown.

OBJECTIVE

To determine if echocardiographic measurements of right heart size and right ventricular (RV) function are associated with survival times in dogs with PH.

ANIMALS

Eighty-two client-owned dogs.

METHODS

Retrospective study where data from medical records and baseline echocardiographic examinations were collected and measured in a standardized manner. Owners or primary veterinarians were contacted for outcome data.

RESULTS

Enlargement of the right atrium (88%), RV (69%), and pulmonary artery (72%) was common. One-third of the cases had reduced RV function quantified by two-dimensional echocardiography-derived tricuspid annular plane systolic excursion (TAPSE). Decreased TAPSE was significantly (P = .008) more common in dogs with PH not secondary to left heart disease (LHD; 43%) compared to dogs with PH secondary to LHD (14%) but median survival times (182, 95% confidence interval [CI] = 39-309 versus 298, 95% CI = 85-314 days, respectively) were not significantly different (P = .78). Right atrial area (hazard ratio [HR] = 2.72, 95% CI = 1.58-4.70), TAPSE < 3.23 mm/kg^0.284 (HR = 2.19, 95% CI = 1.28-3.74), and right heart failure (HR = 2.05, 95% CI = 1.18-3.57) were independently associated with shorter survival time (P ≤ .04).

CONCLUSIONS AND CLINICAL IMPORTANCE

Right atrial area, RV function (TAPSE < 3.23 mm/kg^0.284 ), and right heart failure offer clinically relevant prognostic information in dogs with PH. Results support the quantitative assessment of right heart size and function in dogs with PH.

Risk Factors and Outcomes in Dogs With Respiratory Disease Undergoing Diagnostic Airway Lavage

Advanced diagnostic testing is becoming increasingly important to accurately assess pulmonary parenchymal, airway, and pulmonary vascular diseases in dogs. Due to respiratory system compromise, diagnostic procedures performed under general anesthesia, including thoracic computed tomography (CT) and bronchoalveolar lavage (BAL), are thought to carry significant risk to dogs with respiratory disease. In lieu of performing these diagnostics, empirical medical therapy is often administered, potentially delaying appropriate therapy or providing unnecessary treatment. This study prospectively evaluated risk factors and outcomes for dogs with respiratory disease undergoing general anesthesia for thoracic CT and BAL. Arterial blood gas samples were taken pre- and post-BAL to evaluate pulmonary gas exchange. Pre-BAL arterial partial pressure of oxygen-to-fractional inspired oxygen ratio was used to stratify dogs into groups of mild or moderate to severe disease severity. A novel thoracic CT disease severity scoring system was used to independently stratify dogs into mild or moderate to severe groups. Statistical comparisons between groups were made for signalment, body weight, temperature, pulse, respiratory rate, WBC count, ventilator-acquired pulmonary mechanics (specific compliance and resistance), change in arterial partial pressure of oxygen post-BAL, and outcomes. Seventeen dogs were prospectively enrolled. A comparatively lower heart rate at presentation was the only potential marker of increased disease severity identified when stratified by CT severity score. Arterial partial pressure of oxygen did not significantly decrease post-BAL regardless of disease severity or stratification method. The CT scoring system significantly correlated with the pre-BAL arterial partial pressure of oxygen-to-fractional inspired oxygen ratio. Incidence of post-procedural complications was 18%, with all complications being transient. Mortality as a direct complication of diagnostics was 0%. When considering euthanasia secondary to severity of the underlying disease and poor prognosis or death due to unrelated disease, mortality was 18%. In dogs with respiratory disease undergoing advanced diagnostic procedures, the overall incidence of post-procedural morbidity was low with no mortality directly attributed to the procedures. A novel CT disease severity scoring system was utilized and shows promise as a tool for evaluation of disease severity in this patient population when compared to arterial blood gas analysis.

ACVIM consensus statement guidelines for the diagnosis, classification, treatment, and monitoring of pulmonary hypertension in dogs

Pulmonary hypertension (PH), defined by increased pressure within the pulmonary vasculature, is a hemodynamic and pathophysiologic state present in a wide variety of cardiovascular, respiratory, and systemic diseases. The purpose of this consensus statement is to provide a multidisciplinary approach to guidelines for the diagnosis, classification, treatment, and monitoring of PH in dogs. Comprehensive evaluation including consideration of signalment, clinical signs, echocardiographic parameters, and results of other diagnostic tests supports the diagnosis of PH and allows identification of associated underlying conditions. Dogs with PH can be classified into the following 6 groups: group 1, pulmonary arterial hypertension; group 2, left heart disease; group 3, respiratory disease/hypoxia; group 4, pulmonary emboli/pulmonary thrombi/pulmonary thromboemboli; group 5, parasitic disease (Dirofilaria and Angiostrongylus); and group 6, disorders that are multifactorial or with unclear mechanisms. The approach to treatment of PH focuses on strategies to decrease the risk of progression, complications, or both, recommendations to target underlying diseases or factors contributing to PH, and PH‐specific treatments. Dogs with PH should be monitored for improvement, static condition, or progression, and any identified underlying disorder should be addressed and monitored simultaneously.

Thoracic computed tomographic interpretation for clinicians to aid in the diagnosis of dogs and cats with respiratory disease

In humans, high-resolution computed tomography (CT) is a key diagnostic modality for pulmonary disorders. Its success likely lies in excellent correlation of lung diseases with associated subgross anatomic changes, as assessed by histopathology, and because of a multidisciplinary approach between clinicians, radiologists and pathologists. Although thoracic CT studies have been performed in dogs and cats for nearly three decades, there is a lack of uniformity in both protocols for acquisition and in terminology used to describe lesions. Importantly, terms such as a bronchial, interstitial, and alveolar patterns are inappropriate descriptors for canine and feline thoracic CT imaging changes; instead, lung patterns should be classified as increased or decreased attenuation, nodular patterns, and linear patterns, with specific vocabulary to describe subtypes of lesions. In this manuscript, the authors provide an overview of basic CT principles, strategies to optimize and acquire high-quality diagnostic studies (inclusive of paired inspiratory and expiratory series, contrast and triphasic angiography) and provide a roadmap for systematic interpretation of thoracic CT images.

Clinical features of canine pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis

Background

Histologic features of pulmonary veno‐occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) have been described in dogs but without a thorough clinical description.

Objectives

To report the clinical features, diagnostics, treatment, and outcome of dogs with histologic evidence of PVOD and PCH.

Animals

Fifteen pet dogs meeting histopathologic criteria of PVOD (occlusive remodeling of small‐sized to medium‐sized pulmonary veins) or PCH (alveolar capillary proliferation and congestion), or both.

Methods

Medical records of dogs with PVOD and PCH identified based on histopathologic features between 2003 and 2017 were retrospectively reviewed.

Results

Fifteen dogs met inclusion criteria of a histologic diagnosis of PVOD or PCH or both. Dogs were older (median 11 years) with no apparent breed or sex predisposition. Dogs presented with acute clinical signs (median 3 days), usually respiratory distress. Thoracic radiography (available in 10 dogs) revealed right cardiomegaly and patchy or diffuse interstitial to alveolar patterns, with 9 dogs having a normal left cardiac silhouette. In 5 dogs tested, pulmonary arterial hypertension (PAH) was documented. In all 3 dogs, thoracic computed tomography scans showed pulmonary arterial enlargement and perivascular diffuse nodular ground‐glass opacities. Ten of 15 dogs died within 1 day; median survival was 3 days.

Conclusions and Clinical Importance

In dogs with PAH, the inability to document left‐sided congestive heart failure and failure to identify another cause of signs of respiratory disease should increase suspicion for PVOD and PCH. With increased awareness of PVOD and PCH by clinicians and pathologists, dogs with compatible clinicopathologic features should be evaluated for these pulmonary vascular disorders.