Introduction

The neonatal period is characterized by immaturity of several organic systems and high mortality rates (Moore, 2000). Such immaturity that persists for several months after birth causes the neonatal period to be critical for the adaptation of the neonate which is susceptible to diverse injuries (Hoskins, 2001). The interpretation of laboratory tests, as well as physical examination in neonates represents a diagnostic challenge, especially due to the lack of data reported in the literature. The purpose of this work was to assess the hematological and biochemical profile and serum proteinogram in neonate cats and to determine the changes in these laboratory parameters that occur during the neonatal period.

Materials and Methods

Twenty neonate cats of undetermined breed (10 males and 10 females), weighing 100-110g were used. All animals came from the cat maternity unit of the Botucatu School of Veterinary Medicine and Animal Husbandry of São Paulo State University. Throughout the study period, the neonates were kept with their mothers under adequate hygiene and feeding conditions in accordance with the guidelines of the institutional Animal Welfare and Ethics Committee. Blood samples were collected three days after birth and weekly thereafter (at days 10, 17, 24, 31 and 38). Total and differential white blood cell and RBC counts; hemoglobin concentration; hematocrit; mean cell volume (MCV); mean cell hemoglobin concentration (MCHC); alanine aminotransferase activity (ALT); gamma glutamyltransferase (GGT); glucose; total protein and albumin, alpha-, beta-and gamma-globulin (agarose gel electrophoresis) protein fractions were assessed. Descriptive statistical analysis was performed with software SAS (Statistical Analysis System). PROC ANOVA was performed and whenever the analysis of variance of the major effects revealed significance (P < 0.05), the test of Tukey was used to discriminate the possible similarities and differences among time points.

Results

Mean total red blood cells at 3 and 10 days of age (4.81 and 3.45 X106/mL, respectively) were below the reference values for adults (Table 1). At day 21, the mean value was 3.66 X10⁶/mL, Over the three following weeks, (days 24, 31 and 38), this value increased (3.73; 4.05 and 4.82 X10⁶/mL, respectively). The concentrations of hemoglobin (12.96 g/dL) and hematocrit (37.80%), which were within the reference range at day 3, decreased with time being 6.87 g/dL and 19.65%, at days 24 and 31, respectively. On day 38, these values increased but remained below the minimum rates reported in adults. MCV was higher than the values for adult cats at day 3 (78,66 fL). However, it decreased as weeks went by and was similar to those observed in adults at 38 days of age. MCHC remained unchanged throughout the study period. Total and differential leukocyte counts were within the range established for adults and showed a rise during the study, except for the number of basophils which was higher than in adults. Serum ALT (Table 2) did not significantly change during the study. However, in comparison with the reference values for adult cats, the ALT values observed in neonates were lower until 31 days of age, when they reached the reference values for adult animals. Serum GGT activity showed significant dynamics during the nursing period. It was minimal at 3 days but gradually increased until 38 days of age. Age did not influence glucose levels which were similar to those reported in adults. Serum concentrations of total protein and albumin (Table 3) rose until 5 weeks of age in agreement with values previously reported in neonate cats. The absolute values of alpha and beta globulin fractions were similar to those described in adult animals and increased until day 17 and 24, respectively. Electrophoresis revealed that the absolute values for gamma-globulin fraction decreased during the first four weeks after birth. At days 31 and 38, these values increased but still remained lower than those reported in adults.

Table 1. Means and standard deviation in blood tests of neonate cats at 3, 10, 17, 24, 31 and 38 days of age, and reference ranges for adult and young cats.

Table 2. Means and standard deviations of alanine aminotransferase and gamma glutamyltransferase serum concentrations in neonate cats at 3, 10, 17, 24, 31 and 38 days after birth, and reference range for adult and young cats.

Table 3. Means and standard deviations of total protein, alpha-, beta- and gamma-globulin serum concentrations (g/dL) in neonate cats at 3, 10, 17, 24, 31 and 38 days after birth, and reference range for adult and young cats.

Discussion and Conclusions

The kinetics of hematological development in the study cats of undetermined breed during the neonatal period was similar to that described by Meyers-Wallen et al. (1984), Jain (1993) and Hoskins (2001). The critical period corresponded to the 2nd and 3rd weeks of age with reduction in total red blood cell count and the concentrations of hemoglobin and hematocrit, characterizing neonatal physiological anemia. At birth, there was an increase in mean body volume characterized by neonatal macrocytosis which decreased with age. This fact was associated with replacement of fetal red blood cells by neonatal red blood cells. White blood cell count was within the reference range for adults according to Clinkenbeard & Meinkoth (2000) and in agreement with Tiedemann & Ooyen (1978), who reported that over 60% of the adult values are present in most neonates at birth indicating adequate bone marrow development and maturation. However, these values were lower than the mean considered normal for neonates by other authors such as Meyers-Wallen et al. (1984) and Hoskins (2001). ALT serum values did not significantly change during the study period but were below the reference range established for adults until day 31, when they finally reached it. According to the literature, serum ALT activity is likely to increase with the development of hepatic metabolism (Kaneko et al., 1997; Hoskins, 2001; Levy et al., 2006). Reaching adult mean serum levels may extend over the neonatal period, i.e., 30 days after birth. GGT values clearly showed that this enzyme cannot effectively indicate the ingestion of colostrum in felines.

The value obtained 3 days after birth differed from that reported by Hoskins (2001) in dogs of the same age. During the six-week period, total protein and albumin serum levels rose. At days 3 and 10, total protein was slightly below the values reported for adults by Kaneko et al. (1997). On the other hand, these same values are consistent with those described for neonate and young cats (Kristensen & Barsanti, 1977; McMichael & Dupha, 2000; Hoskins, 2001). This could be explained by the fact that the rate of protein anabolism does not accompany the great body growth and development of neonates during their first weeks of life. Alpha-and beta-globulin fractions were also within the reference range for adult and young cats with values rising until day 24 and remaining stable until day 38. This behavior was similar to that described in caprines (Barioni, 2003) and humans as well. The elevation of these fractions probably reflects hepatic development as protein synthesis mostly occurs in the liver. Gamma-globulin fraction was much lower than the values reported for adult and young cats (older than six months). Given the reduced gammaglobulin fractions observed at 3 days, it is probable that the concentration of this fraction was practically zero before colostrum ingestion as suggested by Yamada et al. (1991). According to these authors, no gamma-globulin levels were detected in fetuses and neonates before colostrum ingestion. At day 10, there was a marked statistical reduction in gamma-globulin levels that remained constant though slightly decreasing until day 24. According to Yamada et al. (1991), acquired immunity starts to decline in cats 3 days after birth with the lowest immunoglobulin concentration occurring between 20 and 25 days of life. Starting at day 31, there was a slight elevation in gamma-globulin concentration and on day 38 there was a considerable statistical increase which was close to the values found at 3 days, probably corresponding to the beginning of the synthesis of immunoglobulins themselves. The physiological immaturity of several systems, therefore, causes the reference laboratory values for neonate cats to differ during the first four weeks of life from those obtained in adults. Reference values specific for neonates should be used to adequately interpret the laboratory tests and the clinical aspects under study.

References

1.  Moore PH. 2000. Cuidado y manejo del neonato p. 211-214. In: Simpson GM, England GCW, Harvey MJ. (Ed.), Manual de reproducción y neonatología en pequeños animales. Harcourt, Madrid.

2.  Hoskins JD. 2001. Hematology of normal dogs and cats and responses to disease. p. 300-343. In: Hoskins JD (Ed.), Veterinary pediatrics, dogs and cats from birth to six months. 3 ed. W. B. Saunders, Philadelphia:,

3.  Meyers-Wallen VN, Haskins ME, Patterson DF. 1984. Hematologic values in healthy neonatal, weanling, and juvenile kittens. American Journal Veterinary Research, 45(7): 1322-1327.

4.  Jain NC. 1993. Erytrocyte physiology and changes in disease. p. 133-158. In: Jain NC. (Ed.), Essentials of veterinary hematology. 4th ed. Lea & Fabiger, Philadelphia.

5.  Clinkenbeard KD, Meinkoth JH. 2000. Normal hematology of the cat. p. 1064-108. In: Feldman BF, Zinkl JG, Jain NC. (Ed.), Schalm's veterinary hematology. 5a ed. Lippincott Willians & Wilkins, Philadelphia.

6.  Tiedmann K, van Ooyen B. 1978. Prenatal hematopoiesis and blood characteristics of the cat. Anatomy and Embryology, 153: 243-267.

7.  Kaneko JJ, Harvey JW, Bruss ML. 1997. Clinical biochemistry of domestic animals. 5th edition. Academic Press, San Diego, p. 157-203.

8.  Levy JK, Crawford PC, Werner, 2006. Effect of age on reference intervals of serum biochemical values in kittens. Journal America Veterinary Medical. Association. 228(7): 1033-1037.

9.  Kristensen F, Barsanti JA. 1977. Analysis of serum proteins in clinically normal pet and colony cats, using agarose electrophoresis. American Journal Veterinary Research, 38(3): 399-402.

10. Mcmichael M, Dhupa, 2000. Pediatric critical care medicine: physiologic considerations. Compendium on Continuing Education the Practicing Veterinarian, 22(3): 220-250.

11. Barioni G. 2003. A influência da idade e da suplementação com vitamina E (acetato de dl-alfa-tocoferol) sobre o hemograma, proteinograma, imunoglobulina G, fragilidade osmótica e metabolismo oxidativo eritrocitário em caprinos da raça Saanen. Botucatu,. 156p. Tese (Doutorado em Medicina Veterinária)--Curso de Pós-graduação em Medicina Veterinária), Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista.

12. Yamada T, Nagai Y, Matsuda M. 1991. Changes in serum immunoglobulin values in kittens after ingestion of colostrum. American Journal of Veterinary Research, 52(3): 393-396.