Immunocytochemical study of canine lymphomas and its correlation with exposure to tobacco smoke

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.

Lymphoma in Border Collies: Genome-Wide Association and Pedigree Analysis

There has been considerable interest in studying cancer in dogs and its potential as a model system for humans. One area of research has been the search for genetic risk variants in canine lymphoma, which is amongst the most common canine cancers. Previous studies have focused on a limited number of breeds, but none have included Border Collies. The aims of this study were to identify relationships between Border Collie lymphoma cases through an extensive pedigree investigation and to utilise relationship information to conduct genome-wide association study (GWAS) analyses to identify risk regions associated with lymphoma. The expanded pedigree analysis included 83,000 Border Collies, with 71 identified lymphoma cases. The analysis identified affected close relatives, and a common ancestor was identified for 54 cases. For the genomic study, a GWAS was designed to incorporate lymphoma cases, putative "carriers", and controls. A case-control GWAS was also conducted as a comparison. Both analyses showed significant SNPs in regions on chromosomes 18 and 27. Putative top candidate genes from these regions included DLA-79, WNT10B, LMBR1L, KMT2D, and CCNT1.

Detection of Lymphoid Markers (CD3 and PAX5) for Immunophenotyping in Dogs and Cats: Comparison of Stained Cytology Slides and Matched Cell Blocks

Immunolabeling on Romanowsky-stained cytology (RSC) slides can be used, although there is limited evidence of its suitability for phenotyping canine and feline lymphomas. A comparison with matched cell blocks (CB) is missing. Immunolabeling on RSC and CB was compared for lymphoid markers (CD3 and PAX5) in 53 lymphomas and 4 chylous effusions from dogs and cats. The influence of pre-analytical variables (species, time of archive, type of specimens and coverslipping) and the interobserver agreement among the 2 observers was assessed. Fewer CD3+ lymphocytes were identified in RSC, while the PAX5 positivity by RSC and CB had a substantial agreement. Immunodetection of CD3 and the diagnosis of a T-cell population on RSC was more difficult. Lower intensity and higher background were noted in RSC. Immunophenotyping was inconclusive in 54% RSC and 19% CB. The interobserver reproducibility of immunophenotyping on CB was substantial, being higher than in RSC. The immunolabeling performance on the RSC of effusion and feline samples was unsatisfactory. The detection of lymphoid markers, especially membranous antigens in retrospective RSC, is affected by the pre-analytical variables: species, time of the archive, and type of specimens. CB are a more consistent type of sample for immunophenotyping purposes.

Vet-OncoNet: Malignancy Analysis of Neoplasms in Dogs and Cats

Simple Summary

An overview analysis of tumors in dogs and cats, dividing them into malignant and benign, may provide previously unknown information about the biological behavior of tumors in these species and may serve many veterinarians as a support for clinical decision making. Based on a sample of 16,272 cancer records, including 3266 cats and 13,006 dogs, the analysis found that cats have a fourfold risk of malignant tumors, as in some topographies. Sex appears to play a role in the malignancy only in dogs. Some dog breeds (Pit bull and Boxer) have a higher risk of malignant tumors as opposed to Shih tzu and Yorkshire terrier. District of residence was not relevant in predicting malignancy risk. Most importantly, the risk of malignant tumors increases by 20% every three years.

Abstract

Analysis of canine and feline tumor malignancy data can help clinicians identify high-risk patients and make more accurate decisions. Based on a sample of 16,272 cancer records, including 3266 cats and 13,006 dogs, collected from January 2019 to December 2021 in the Vet-OncoNet Network database, this study aimed to compare the tumor malignancy profile between cats and dogs, considering animal-related factors (sex, age, and breed), topography, and geographic location using a mixed-effects logistic regression model. Cats had a higher proportion of malignant tumors (78.7%) than dogs (46.2%), and the malignancy profile was very different regarding tumors’ topographies. The mean age of malignant tumors occurred eight months later than benign ones (9.1, SD = 3.4; 9.8, SD = 3.2), in general. Species (OR = 3.96, 95%CI 3.57: 4.39) and topography (MOR = 4.10) were the two most important determinants of malignancy risk. Female dogs had a higher risk than male dogs (OR = 1.19, 95%CI 1.08: 1.31), which does not appear to be the case in cats (OR = 0.98, 95%CI 0.77: 1.23). Breed contributed significantly to differences in malignancy risk in dogs (MOR = 1.56), particularly in pit bulls and boxers. District of residence was not so relevant in predicting malignancy risk (MOR = 1.14). In both species, the risk of malignancy increased by approximately 20% every three years. It could be hypothesized that species differences in genetic structure may contribute to tumor malignancy.

Environmental exposures and lymphoma risk: a nested case-control study using the Golden Retriever Lifetime Study cohort

Lymphoma is the second most common cancer affecting Golden Retrievers and is hypothesized to arise through a complex interaction of genetic and environmental factors. The aim of this nested case–control study was to investigate the association between potential environmental pollutant sources and lymphoma risk among Golden Retrievers participating in the Golden Retriever Lifetime Study. Forty-nine Golden Retrievers with non-cutaneous lymphoma and 98 Golden Retrievers without a history of cancer matched by age, sex and neuter status were selected from the Golden Retriever Lifetime Study cohort. Geographic proximity between each dog’s primary residence and nine potential sources of environmental pollution was determined. In addition, the average annual ozone and airborne fine particulate matter levels for each dog’s county of residence and owner-reported secondhand smoke exposure were evaluated. Environmental pollution sources of interest included chemical plants, municipal dumps, manufacturing plants, incineration plants, railroad embankment tracks, landfills, coal plants, high-voltage transmission lines, and nuclear power plants. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for each exposure of interest. Subgroup analyses were conducted to evaluate whether associations differed among 1) dogs with multicentric lymphoma, 2) dogs with B-cell lymphoma, and 3) dogs with T-cell lymphoma. No variables reached statistical significance when evaluating all cases together. However, cumulative exposure burden (household proximity to 3 or more pollution sources) approached significance within the multicentric lymphoma subgroup (OR = 2.60, 95%CI 0.99–6.86, p-value = 0.053). Patterns emerged among B- and T-cell subgroups, but none reached statistical significance. Ongoing research is warranted to discern if different environmental mechanisms may be driving B- and T-cell lymphoma immunophenotypes, consistent with previously reported regional differences in subtype prevalence.

Lymphoma is a common cancer affecting dogs, particularly Golden Retrievers. By identifying risk factors for lymphoma, work can be done to reduce harmful exposures or increase monitoring among dogs at a higher risk of disease. Using a subset of dogs from the Golden Retriever Lifetime Study, we sought to investigate whether dogs with lymphoma were more likely to live near certain environmental pollutant sources than dogs without lymphoma.

Forty-nine Golden Retrievers with non-cutaneous lymphoma and 98 Golden Retrievers without a history of cancer were selected from the Golden Retriever Lifetime Study Cohort. We evaluated how close each dog lived to nine environmental pollutant sources: chemical plants, municipal dumps, manufacturing plants, incineration plants, railroad embankment tracks, landfills, coal plants, high-voltage transmission lines, and nuclear power plants. Additionally, we evaluated individual exposure to secondhand smoke, and average annual ozone and particulate matter exposure (as surrogate measures for air pollution) for each dog’s county of residence.

None of the exposures examined were associated with an increased lymphoma risk in this population. More research is needed, including direct biomonitoring, to determine whether specific environmental exposures are associated with lymphoma in the Golden Retriever breed.

Age- and breed-matched retrospective cohort study of malignancies and benign skin masses in 660 dogs with allergic dermatitis treated long-term with versus without oclacitinib

OBJECTIVE

To compare the cumulative incidences of malignancies and benign skin masses and the mean age at death or euthanasia in dogs with allergic dermatitis treated long-term with versus without oclacitinib.

ANIMALS

660 client-owned dogs.

PROCEDURES

Medical records were searched to identify dogs with allergic dermatitis treated for ≥ 6 months with oclacitinib (exposed dogs; n = 339) versus other available treatments before the introduction of oclacitinib (nonexposed dogs; 321) and with ≥ 24 months of follow-up information available. Nonexposed dogs were age and breed matched with 321 of the exposed dogs; data for the remained 18 exposed dogs were included in statistical analyses. Results for cumulative incidences of malignancies and other variables were compared between groups, and the effect of daily maintenance dosage of oclacitinib on cumulative incidences of malignancies and other skin masses was evaluated within the exposed group.

RESULTS

No meaningful differences were detected in the cumulative incidences of malignancies and overall skin masses or the mean age at death or euthanasia for dogs in the exposed group (16.5% [56/339], 56.6% [192/339], and 11.2 years [n = 80], respectively) versus the nonexposed group (12.8% [41/321], 58.3% [187/321], and 11.8 years [71], respectively). There was no association identified between daily maintenance dosage of oclacitinib and odds of malignancy or benign skin masses for dogs in the exposed group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that long-term treatment with oclacitinib did not pose additional risk for malignancy in dogs; however, veterinarians should continue to observe FDA-approved label warning and precaution statements for oclacitinib and regularly screen for neoplasia in dogs with allergic skin disease treated with or without oclacitinib.

Comparative Exposure Assessment Using Silicone Passive Samplers Indicates That Domestic Dogs Are Sentinels To Support Human Health Research

Silicone wristbands are promising passive samplers to support epidemiological studies in characterizing exposure to organic contaminants; however, investigating associated health risks remains challenging because of the latency period for many chronic diseases that take years to manifest. Dogs provide valuable insights as sentinels for exposure-related human disease because they share similar exposures in the home, have shorter life spans, share many clinical/biological features, and have closely related genomes. Here, we evaluated exposures among pet dogs and their owners using silicone dog tags and wristbands to determine if contaminant levels were correlated with validated exposure biomarkers. Significant correlations between measures on dog tags and wristbands were observed (r_s = 0.38-0.90; p < 0.05). Correlations with their respective urinary biomarkers were stronger in dog tags compared to that in human wristbands (r_s = 0.50-0.71; p < 0.01) for several organophosphate esters. This supports the value of using silicone bands with dogs to investigate health impacts on humans from shared exposures.