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Anemia is a common alteration of the hemogram in cats. To date there are only few studies on the prevalence and frequency of the different types of anemia in feline patients.
The objective of this prospective study was to describe the medical reports of anemia in 194 cats with a hematocrit <0.26 l/l presented at the Small Animal Clinic, Freie Universität Berlin, between October 2009 and March 2011. The diagnostic value of the erythrocytic osmotic fragility as well as other parameters (for instance, total protein and bilirubin concentration) and the outcome of cats in the various anemia groups were to be evaluated. Inclusion criterion was the availability of a comprehensive diagnostic work-up (laboratory work, diagnostic imaging). Based on these data the cats were assigned to one of the following groups: acute blood loss anemia (BA), anemia of inflammatory disease (AID), hemolytic anemia (HA), anemia of renal disease (ARD), intramedullary induced non regenerative anemia (INR), anemia of unknown origin. In order to evaluate the erythrocytic osmotic fragility additional information obtained from 95 cats from two previous investigations was included. The control group consisted of 104 healthy cats.
The majority of the 194 anemic cats had BA (38.7%). In most cases this was related to trauma (52%) because the clinic´s patient population consists of many cats presented with traumas following falls from a height and car accidents. Other frequent causes of hemorrhage were hematuria due to urinary tract obstruction in male cats (17%) and hemostatic disorders (12%). Anemia of inflammatory and neoplastic (less frequent) disease was diagnosed in 22.2% of the cases. HA was similarly common (18%). Half of those cases (49%) were proven or suspected to be immune mediated. Four cats were diagnosed with hemoplasmosis. Rare causes of anemia included ARD (9.3%) and INR (6.7%). Cats suffering from INR were frequently infected with retroviruses (46%) or had neoplasia (46%). A small number of the patient population (5.1%) could not be assigned to one of the groups classified above.
In this study, no statistically significant difference could be observed between the various anemic groups regarding gender (p=0.158) and breed (p=0.281). However, cats with AID and ARD were significantly older than those of the other groups (p Cats with hemolysis, blood loss anemia and INR had a significantly lower hematocrit than those with AID (p The mean osmotic fragility (MOF) of the healthy control cats ranged from 0.44-0.58%. An increased MOF was seen particularly in cats with HA (p<0.001), INR (p=0.001) and ARD (p<0.001) and less often in cats with AID (p<0.001) and blood loss anemia (p=0.009).
Blood transfusions were primarily given to cats with blood loss (49%) and hemolytic anemia (54%), especially immune mediated hemolytic anemia (76%). Patients with AID only occasionally (16%) received blood transfusions. Cats with ARD received no blood transfusion. Cats with BA and HA had the highest survival rate (61% and 63%, respectively). Cats with AID had a worse survival rate (32%) and none of the patients with ARD and INR survived.
In the present study, blood loss anemia was the most common type of anemia in cats. Anemia of inflammatory disease and hemolytic anemia were also detected frequently, whereas anemia of renal disease and intramedullary induced non regenerative anemia were less common. Parameters such as total protein and bilirubin concentration as well as the mean corpuscular volume and the determination of the mean osmotic fragility can contribute to the classification of the anemia. Prognoses of outcome of anemic cats should not be based solely on the degree of anemia.