title: Hematology and biochemistry of aging-evidence of "anemia of the elderly" in old dogs.
abstract: BACKGROUND
  Effects of aging on hematologic and biochemical variables are well described in people. Anemia of the elderly is attributed to iron deficiency, anemia of chronic disease, chronic kidney disease, myelodysplasia, or idiopathic causes. Limited studies have examined these variables in aging dogs, but they have typically examined single breeds in research settings.
  
  
  OBJECTIVE
  The objective of this study was to identify differences in CBC and biochemistry values between adult and aged dogs of many breeds.
  
  
  METHODS
  Dogs presenting for wellness examinations and minor dental/elective surgeries that were otherwise clinically healthy were retrospectively identified. Dogs were categorized by age: adult (1-7.9 years), senior (8-11.9 years), and geriatric (12+ years). Standard CBC and biochemistry data were collated. Asian breeds, Greyhounds, and dogs with data indicating overt underlying disease were excluded. The Kruskal-Wallis test was used to compare groups with statistical significance set at P ≤ .05.
  
  
  RESULTS
  Hematocrit, MCV, and serum iron decreased with age, indicating possible iron-restricted erythropoiesis (IRE), due to iron deficiency or low-grade chronic inflammation. Total proteins, globulins, and platelet counts increased with age while albumin decreased, suggesting low-grade inflammation. Urea was increased in older dogs without a concurrent increase in creatinine, which points toward gastrointestinal bleeding or dehydration.
  
  
  CONCLUSIONS
  Clinically healthy, aging dogs have changes in laboratory variables that indicate altered physiologies compared to younger adult animals, including evidence of IRE, inflammation, and potential gastrointestinal bleeding, suggesting a similar trend to that of elderly human beings. Future studies will examine markers of iron metabolism and inflammation in aging dogs.
authors.affiliation: Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Lauren B
authors.initials: LB
authors.lastname: Radakovich
authors.affiliation: Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Pannone
authors.affiliation: Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Truelove
authors.affiliation: Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Christine S
authors.initials: CS
authors.lastname: Olver
authors.affiliation: Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, USA.
authors.forename: Kelly S
authors.initials: KS
authors.lastname: Santangelo
mesh_terms: D000375:Aging; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000662:veterinary*; D000818:Animals; D004283:Dog Diseases / Q000097:blood*; D004285:Dogs / Q000502:physiology*; D004920:Erythropoiesis; D005260:Female; D006400:Hematocrit / Q000662:veterinary; D006405:Hematology; D007249:Inflammation; D000090463:Iron Deficiencies; D008297:Male; D012189:Retrospective Studies
keywords: Aging; complete blood count; dogs; inflammation; iron-restricted erythropoiesis; serum biochemistry