The high prevalence of macrothrombocytopenia (large platelets plus thrombocytopenia) in the Cavalier King Charles Spaniel (CKCS) is well-recognized. Platelets counts are moderately low (30-90, 000/µL), but these dogs rarely have signs of bleeding. Platelets in this breed should be counted manually, because automated blood cell counters cannot distinguish the large platelets from erythrocytes and therefore underestimate the true platelet count. Thus, members of this breed often exhibit idiopathic asymptomatic thrombocytopenia.

Platelet counts were studied in 105 clinically healthy CKCS from Scandinavia; 81 offspring and 26 parents. Age, gender, or heart murmur (mitral insufficiency being common in this breed) did not influence the measured manual platelet counts. Thrombocytopenia was found in 46% of the parents, but the mean parental platelet count had no influence on the platelet counts of the offspring. Pedigree analysis indicated that the thrombocytopenia segregated as an autosomal recessive trait, and that 100,000 platelets/µL was the expected lower limit of normal.
Reference: Pedersen et al, J Vet Int Med 16: 169-173, 2002.

A single injection of inulin at 3000 mg/m² was used to determine the glomerular filtration rate (GFR) in 53 cats. Thirty of the cats were healthy young adults, and the remaining 23 were either more than 10 years old or had borderline serum creatinine concentrations. Results of concomitant inulin and iohexol clearance showed excellent correlation between the two methods. Thus, a single injection of inulin followed by one blood sample taken 3 hr later proved to be a valuable diagnostic tool for routine assessment of GFR in cats.
Reference: Haller et al, J Fel Med and Surg 5: 175-181, 2003.