title: Survey of cardiovascular pathology in wild urban Rattus norvegicus and Rattus rattus.
abstract: Norway (Rattus norvegicus) and black rats (Rattus rattus) are common commensal pests, yet little is known about the ecology of wild rats, including their natural diseases. We describe microscopic cardiovascular pathology in a subset of a sample of 725 wild urban rats. Changes observed in the pulmonary blood vessels (n = 199) included arteriolar medial hypertrophy (20.1%, n = 40) and blood vessel mineralization (19.1%, n = 38). Microscopic changes in the heart (n = 200) included myocarditis (33.5%, n = 67), fibrosis (6.0%, n = 12), mineralization (9.5%, n = 19), myocardial degeneration (22.0%, n = 44), and right ventricular hypertrophy (4.5%, n = 9). Rats with myocarditis, fibrosis, or myocardial degeneration were grouped into a composite variable: cardiomyopathy. Statistical analysis showed that the odds of being affected by cardiomyopathy were greater in male rats (odds ratio [OR] = 2.49; 95% confidence interval [CI] = 1.12-5.55) and heavier rats (OR = 1.14; 95% CI = 1.09-1.20). The odds of pulmonary arteriolar medial hypertrophy was greater in sexually mature rats (OR = 2.35; 95% CI = 0.75-7.36), while the odds of pulmonary vessel mineralization were greater in heavier rats (OR = 1.07; 95% CI = 1.03-1.11) and in black rats (OR = 5.35; 95% CI = 1.62-17.69) compared to Norway rats. To our knowledge, this is the first detailed description of pathology in the cardiovascular system of wild rats and demonstrates that cardiovascular disease is common. The impact of these lesions on individual and population health remains to be investigated.
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada jamie.rothenburger@usask.ca.
authors.forename: J L
authors.initials: JL
authors.lastname: Rothenburger
authors.affiliation: School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada Animal Health Centre, British Columbia Ministry of Agriculture, Abbotsford, British Columbia, Canada.
authors.forename: C G
authors.initials: CG
authors.lastname: Himsworth
authors.affiliation: Department of Comparative Medicine, School of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Treuting
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Canadian Cooperative Wildlife Health Centre, National Headquarters, Saskatoon, Saskatchewan, Canada.
authors.forename: F A
authors.initials: FA
authors.lastname: Leighton
mesh_terms: D000818:Animals; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D004463:Ecology; D005260:Female; D008297:Male; D015995:Prevalence; D051381:Rats; D012376:Rodent Diseases / Q000453:epidemiology* / Q000473:pathology
keywords: Rattus norvegicus; Rattus rattus; animals; cardiovascular diseases; disease; heart; pathology; pulmonary artery; rats; wild