Association between environmental dust exposure and lung cancer in dogs

Environmental exposure and cancer occurrence in dogs: a critical appraisal of evidence

Cancer is a significant contributor to morbidity and mortality in humans and is also the leading cause of death in dogs. It is estimated that up to 20 % of human cancers can be explained by environmental exposures to carcinogens. It has been hypothesized that companion animals such as dogs could not only be a model for the complex pathogenic processes of human cancers, but also act as sentinels for environmental carcinogens due to their relative shorter longevity, spontaneous occurrence of tumours, and intimate relationship with our everyday environments. This review aimed to provide the epidemiological evidence on the role of the environment in the development and progression of tumours in the canine species.

Canine on the Couch: The New Canary in the Coal Mine for Environmental Health Research

Human health is intimately connected and tied to the health of our environment and ecosystem, with only a very small fraction of the risk for chronic diseases explained by genetics alone. Companion animals are prone to disease types that are shared with people, including cancers and endocrine disorders, reinforcing the thought that environmental factors contribute to the risks for chronic diseases. These factors include air and water pollution and the built environment. As such, there is increasing interest in pursuing research with companion animals, and specifically dogs, as sentinel species to inform comparative health assessments and identify risk factors for disease. Of the canine diseases for which environmental exposure research has been published, cancers have received the most attention. This review summarizes two main aspects of this comparative approach: (1) cancers that occur in dogs and which are similar to humans and (2) research investigating environmental exposures and health outcomes in dogs. The goal of this review is to highlight the diverse conditions in which pet dogs may provide unique perspectives and advantages to examine relationships between environmental exposures and health outcomes, with an emphasis on chemical pollution and cancer. Furthermore, this review seeks to raise awareness and stimulate discussion around the best practices for the use of companion animals as environmental health sentinels.

Pulmonary Adenocarcinoma with Cutaneous Metastasis in a Dog

Primary lung cancer is rare in dogs and depending on the tumour stage and subtype, the prognosis can be poor. In this report, we describe a 10 year-old female intact Yorkshire terrier that presented progressive weight loss and chronic pain of unknown origin. Due to the poor condition of the dog, it was subsequently euthanized. Post-mortem evaluation revealed a single large mass in the left caudal lung lobe, with numerous pale, proliferative lesions of various sizes dispersed throughout all the lobes. Additionally, a solitary skin mass was palpated on the mid-thoracic body wall. Histopathological examination of the lung samples revealed multiple distinct, non-encapsulated, expansive neoplastic epithelial cell proliferations with dense cellularity, exhibiting growth patterns, ranging from papillary to micropapillary to solid, accompanied by central areas of necrosis. In some areas, microvilli-like structures were observed on the luminal cytoplasmic margins of the neoplastic cells. The histopathology of the skin mass closely resembled that of the lung. Electron microscopy of the skin samples revealed regions containing cells resembling the respiratory epithelium, along with cells exhibiting processes or microvilli indicative of cilia. The diagnosis was pulmonary adenocarcinoma with cutaneous metastasis. This is the first report of a canine with primary lung cancer that metastasized to the skin.

Klinisch-pathologische Befunde, postoperative Überlebenszeiten und prognostische Faktoren bei Hunden mit primären Lungenkarzinomen

Einleitung Primäre Karzinome der Lunge (PLK) beim Hund sind selten, ihre Behandlung erfolgt chirurgisch. Ziel dieser Studie war die Untersuchung klinisch-pathologischer Befunde, postoperativer medianer Überlebenszeiten (mÜZ) und prognostischer Faktoren.

Material und Methoden Retrospektive Auswertung von 61 Hunden mit 62 PLK, die zwischen 2007 und 2017 chirurgisch behandelt wurden. Die statistische Auswertung erfolgte mittels Kaplan-Meier und Logrank Methoden.

Ergebnisse Von 62 PLKs lagen 35 (56 %) peripher im Lungenlappen, 21 (34 %) hilusnah und 6 (10 %) betrafen den gesamten Lungenlappen. In 49 Fällen lagen differenzierte Adenokarzinome vor; niedrig differenzierte bzw. anaplastische Karzinome (n = 10) und Plattenepithelkarzinome (n = 2) waren deutlich seltener. Eine Prädisposition für bestimmte Lungenlappen war nicht nachzuweisen. Dreizehn (21 %) Patienten zeigten keine und 10 (16 %) nur unspezifische, nicht auf den Respirationstrakt hinweisende Symptome. Insgesamt zeigten 48 (79 %) Hunde klinische Symptome wie Husten, Dyspnoe, Lethargie, Gewichtsverlust, Leistungsschwäche, Erbrechen und/oder Fieber. Die tracheobronchialen Lymphknoten (TBLN) waren in 9 von 51 untersuchten Fällen histologisch positiv für Metastasierung (N1) und negativ (N0) in 42 Fällen (nicht untersucht n = 10). Daten zum Langzeitverlauf waren für 50 Patienten verfügbar. Prognostisch relevante Variablen waren Lymphknotenmetastasierung in die TBLN (mÜZ: N1 41 Tage, N0 570 Tage; p < 0,01), Lungenmetastasen (mÜZ: M1 125 Tage, M0 630 Tage; p < 0,01), histologischer Subtyp (mÜZ: differenzierte Karzinome 620 Tage; andere Karzinome 135 Tage; p < 0,01), Tumordurchmesser größer als 3 cm (mÜZ < 3 cm 1155 Tage, ≥ 3 cm 330 Tage; p = 0,02) und Tumorlokalisation (mÜZ: hilusnah 330 Tage, peripher 650 Tage; p = 0,04).

Schlussfolgerung Beim PLK sind TBLN Status, Organmetastasen, Tumorlokalisation, histologischer Subtyp und Tumorgröße prognostisch relevante Kriterien. Hunde ohne prognostisch negative Faktoren können lange Überlebenszeiten aufweisen. In mehr als einem Drittel der Fälle bleiben die Tumoren asymptomatisch (21 %) bzw. ohne respirationstraktspezifische (16 %) Symptome.

Fifteen-year surveillance of pathological findings associated with death or euthanasia in search-and-rescue dogs deployed to the September 11, 2001, terrorist attack sites

OBJECTIVE

To compare the cause of death (COD; whether by natural death or euthanasia for poor quality of life caused by a primary pathological condition) between search-and-rescue (SAR) dogs deployed to the World Trade Center, Pentagon, or Fresh Kills Landfill on Staten Island following the 9/11 terrorist attacks and SAR dogs that were not deployed to these sites.

ANIMALS

95 deployed SAR dogs (exposed dogs) and 55 nondeployed SAR dogs (unexposed dogs).

PROCEDURES

Following natural death or euthanasia, 63 dogs (44 exposed and 19 unexposed) underwent a necropsy examination. For the remaining 87 dogs, the COD was categorized on the basis of information obtained from medical records or personal communications.

RESULTS

The median age of death was 12.8 years for exposed dogs and 12.7 years for unexposed dogs. The COD was not impacted by deployment status. In the 150 exposed and unexposed dogs, degenerative conditions were the most common COD followed by neoplasia. Respiratory disease was infrequent (overall, 7 [4.7%] dogs); 4 of 5 cases of pulmonary neoplasia occurred in unexposed dogs. However, in dogs that underwent necropsy, pulmonary particulates were reported significantly more often in exposed dogs (42/44 [95%]), compared with unexposed dogs (12/19 [63.2%]).

CONCLUSIONS AND CLINICAL RELEVANCE

No difference was found in the COD on the basis of disease category and organ system involved between exposed and unexposed SAR dogs. The long life spans and frequency of death attributed to degenerative causes (ie, age-related causes) suggested that the risk of long-term adverse health effects in this population of SAR dogs was low.

Taxonomic Distribution of Neoplasia Among Non-Domestic Felid Species Under Managed Care

As evidenced by numerous case reports from zoos, neoplasia in felids is common, but most reports are limited to Panthera species in North America or Europe. In order to obtain a wider epidemiologic understanding of neoplasia distribution, necropsy records at seven facilities (USA, Mexico, Colombia, Peru, and Brazil) were evaluated. In contrast to others, this study population (195 cases, 16 species), included many non-Panthera felids. Overall neoplasia prevalence was 28.2% (55/195). Panthera species had a higher prevalence of neoplasia than non-Panthera species (52.5%; vs. 13.0%). Lions (66.7%), jaguars (55.0%), and tigers (31.3%) had the highest species-specific prevalence of neoplasia. Neoplasms in Panthera species were more frequently malignant than in non-Panthera (86.1% vs. 55.6%). The systems most commonly affected were the reproductive, hematolymphoid, and respiratory. The range of management conditions and more varied genetic backgrounds support a robust taxonomic pattern and suggest that the reported propensity for neoplasia in jaguars may have a genetic basis at a taxonomic level higher than species, as lions and tigers also have high prevalence. Given the high prevalence of neoplasia and high likelihood of malignancy, routine medical exams in all nondomestic felids, but Panthera species in particular, should include thorough assessments of any clinical signs of neoplasia.

A Contemporary Retrospective Study of Survival in Dogs With Primary Lung Tumors: 40 Cases (2005-2017)

Objective: To report the median survival time in a contemporary cohort of dogs with primary lung tumors and intrathoracic nodal metastasis.

Design: Retrospective Case Series.

Animals (or sample): Dogs with primary lung tumors treated with lung lobectomy and lymph node biopsy.

Procedures: The medical record database at Colorado State University was queried for dogs with primary lung tumors from January 1, 2005 to December 31, 2017. Patients were identified for inclusion if they had lung lobectomy and an intrathoracic lymph node biopsy performed. The median survival time (MST) for lymph node positive (LN+) and negative dogs (LN–) was calculated as well as the MST in dogs that did or did not receive adjuvant chemotherapy. Differences were compared between groups with significance set at p < 0.05.

Results: The MST in LN+ dogs (n = 11) was 167 days which was not statistically different from LN– dogs (n = 29) at 456 days (p = 0.2407). No significant difference in the MST in LN+ dogs was identified between dogs that received adjuvant chemotherapy (n = 4; 110 days) and those that did not receive adjuvant chemotherapy (n = 6; 125 days) (p = 0.4409). There was no difference in survival time in LN– dogs receiving chemotherapy (n = 12; 335 days) as compared to those LN– dogs (n = 10) that did not receive adjuvant chemotherapy (258.5 days; p = 0.6475).

Conclusions and Clinical Relevance: The survival of primary pulmonary neoplasia in dogs with intrathoracic nodal metastasis is longer than previously reported in this contemporary cohort. Chemotherapy did not appear to improve survival in LN+ or LN– dogs. The combination of tumor size between 100 and 999 cm³ and positive lymph node status significantly reduced survival.

Evaluation of intrinsic and extrinsic risk factors for dog visceral hemangiosarcoma: A retrospective case-control study register-based in Lazio region, Italy

The genetic and breed susceptibility of visceral hemangiosarcoma in dogs has been studied, but there is no evidence of environmental risk factors as reported in human medicine. We conducted a case-control study in which the sampling population was the list of canine oncology cases of the Animal Tumour Registry of Lazio region, Italy (2009-2017). We defined cases as dogs with visceral hemangiosarcoma and controls as dogs affected by another neoplasm. The ratio between controls and cases was 3:1. Analysed variables were: age, weight, sex, reproductive status, size, breed, nutrition habit, living environment and location of the house. We performed a preliminary univariate analysis to select potential risk factors (p-value < 0.2) then entered in a forward stepwise logistic regression model. Ninety-three cases enrolled in the study were compared with 279 controls. The multivariable logistic regression identified age, reproductive status and breed as significant risk factors. Results showed an increasing risk with increasing age for age classes 6-10 and > 10 years old (OR = 9.69, 95 % CI: 1.21-77.62; OR = 14.01, 95 % CI: 1.65-119.03). Neutered animals (male and female) were at greater risk compared to intact ones. The breeds at greatest risk were German shepherd (OR = 4.17, 95 % CI: 1.25-13.86) and mixed breed (OR = 3.50, 95 % CI: 1.44-8.51). The last finding could be explained by the genetic origin of the animals, which may include German shepherd or another possible breed at risk. No other individual or environmental variables were identified as risk factors. The findings of this work indicate that genetic predisposition is the key element in visceral hemangiosarcoma development.

Identification of Recurrent Activating HER2 Mutations in Primary Canine Pulmonary Adenocarcinoma

PURPOSE

Naturally occurring primary canine lung cancers share clinicopathologic features with human lung cancers in never-smokers, but the genetic underpinnings of canine lung cancer are unknown. We have charted the genomic landscape of canine lung cancer and performed functional characterization of novel, recurrent HER2 (ERBB2) mutations occurring in canine pulmonary adenocarcinoma (cPAC).

EXPERIMENTAL DESIGN

We performed multiplatform genomic sequencing of 88 primary canine lung tumors or cell lines. Additionally, in cPAC cell lines, we performed functional characterization of HER2 signaling and evaluated mutation-dependent HER2 inhibitor drug dose-response.

RESULTS

We discovered somatic, coding HER2 point mutations in 38% of cPACs (28/74), but none in adenosquamous (cPASC, 0/11) or squamous cell (cPSCC, 0/3) carcinomas. The majority (93%) of HER2 mutations were hotspot V659E transmembrane domain (TMD) mutations comparable to activating mutations at this same site in human cancer. Other HER2 mutations were located in the extracellular domain and TMD. HER2 ^V659E was detected in the plasma of 33% (2/6) of dogs with localized HER2 ^V659E tumors. HER2 ^V659E cPAC cell lines displayed constitutive phosphorylation of AKT and significantly higher sensitivity to the HER2 inhibitors lapatinib and neratinib relative to HER2-wild-type cell lines (IC₅₀ < 200 nmol/L in HER2 ^V659E vs. IC₅₀ > 2,500 nmol/L in HER2 ^WT).

CONCLUSIONS

This study creates a foundation for molecular understanding of and drug development for canine lung cancer. These data also establish molecular contexts for comparative studies in dogs and humans of low mutation burden, never-smoker lung cancer, and mutant HER2 function and inhibition.

Interstitial lung diseases in dogs and cats part II: Known cause and other discrete forms

In addition to idiopathic interstitial pneumonias, interstitial lung diseases (ILDs) can occur secondary to known causes or be classified as discrete syndromes. Also known as diffuse parenchymal lung diseases, the ILDs represent a heterogenous group of non-infectious, non-neoplastic disorders characterized by varied patterns of inflammation and fibrosis. Characteristically associated with the true interstitium (i.e. the anatomic space lined by alveolar epithelial cells and capillary endothelial cells and the loose-binding connective tissue), it is important to understand ILDs are associated with pathology of the distal lung parenchyma and thus lesions can be bronchiolocentric or resemble alveolar filling disorders. Injury to the distal lung can occur via inhalation or hematogenous routes. This review will build on a proposed classification scheme adapted from human medicine to describe known cause and discrete forms of ILDs in dogs and cats.

Concurrent Occurrence of Lower Respiratory Aspergillosis and Pneumoconiosis in a Turkey Flock

This study describes a concurrent occurrence of lower respiratory aspergillosis and pneumoconiosis in a turkey flock. From one flock of 1000 turkeys, 4 clinically affected turkeys were examined pathologically and microbiologically. Clinically affected turkeys showed anorexia, lethargy, drooping of the wing, vomiting, dyspnea and open-beak breathing, or sudden dead. Gross lesions were observed in the air sacs and lungs which presented white to yellowish granulomas of varying size. Microscopic there was multifocal granulomatous airsacculitis and pneumonia. At the center of the granulomas, fungal hyphae were clearly highlighted in the lungs and air sacs by Gomori methenamie silver (GMS) staining. In the microbiological cultivation of the affected lungs and air sacs, Aspergillus fumigatus was isolated on Sabouraud dextrose agar. Furthermore, dark black dust accumulations were present in the cytoplasm of macrophages or interstitial tissue in the lungs and air sacs. There were also fibrosis and lymphohistiocytic cell infiltrations around the particles. Overall, this study could implicated that pneumoconiosis might be a predisposing factor in the development of respiratory aspergillosis in turkeys.

EGFR overexpression in canine primary lung cancer: pathogenetic implications and impact on survival

This study reports the main clinicopathological features of primary lung cancer (PLC) in 37 dogs, with special regard to the pathogenetic and prognostic role of epidermal growth factor receptor (EGFR) overexpression. For each case the following characteristics were evaluated: tumour-node-metastasis (TNM) stage, tumour histotype, histological grade, mitotic activity and immunohistochemical expression of EGFR. In samples with available normal lung tissue, the amount of background anthracosis was also measured by image analysis. In 27 tumours (73%) a variable number of cells (20-100%) stained positively for EGFR. The proportion of EGFR-positive tumours was significantly higher in cases with background anthracosis, and the amount of anthracosis was correlated with the percentage of positive tumour cells. Additionally, a trend towards shortened survival for the high EGFR group was observed. These findings suggest an involvement of EGFR signalling pathway in canine PLC, a negative prognostic significance of protein overexpression and its potential implication in air pollution carcinogenesis.