Hematological and serum biochemical profile in cattle experimentally infected with foot-and-mouth disease virus

Abstract

Background and aim: Foot-and-mouth disease (FMD) is an acute viral infection affecting cloven-hoofed animals causing vesicular erosions in the oral cavity and interdigital space. The present study was undertaken to ascertain the time-dependent changes in clinical, hematological, and biochemical profiles in different breeds of cattle following experimental infection.

Materials and methods: The animals were inoculated with 1.0×10⁴ 50% bovine tongue infectious dose (BTID₅₀) by intradermolingual route. Clinical signs were observed, and blood/serum samples were collected at different time intervals.

Results: The white blood cell count declined sharply on days 7-13 and recovered on day 14 post-FMD infection. Biochemical analysis of serum markers for vital organ profile revealed no marked damage. However, a significant increase in blood urea nitrogen (BUN) value indicated pre-renal azotemia. Transient hyperthyroidism was indicated by the rise in T3 and T4 that can be correlated with a decrease in triglyceride and total cholesterol levels. In the cardiac damage assessment study, a distinct breed difference was observed wherein Malnad Gidda calves showed no cardiac damage.

Conclusion: Except thyroid profile, BUN, and creatine kinase-myocardial band, all other serum biochemical parameters showed no significant abnormalities, whereas lymphopenia is the only hematological change and it is suggested that effective ameliorative measures should be targeted mainly on the feed/water intake, thyroid gland, and the level of lymphocytes.

Keywords: biochemical profile; experimentally infected indigenous and crossbred calves; foot-and-mouth disease; hematological profile.

Figure-1

Progress of clinical signs in calves experimentally infected with the foot-and-mouth disease virus. (a) Rectal temperature (mean±standard error of the mean [SEM]) during the course of acute foot-and-mouth disease virus (FMDV) infection. The elevated temperature was observed on day 3 post-infection and subsided by day 5 post-infection, **p<0.01. (b) Foot lesion score (mean±SEM) during the course of FMDV infection. The foot lesions peaked on day 5 post-infection, and disappeared by 21 days post-infection, ***p<0.001.

Figure-2

Serum biochemical profile of calves infected with foot-and-mouth disease virus (FMDV). (a-h) Indicate serum total protein, albumin, A: G ratio, aspartate transaminase, alanine transaminase, gamma-glutamyl transferase, blood urea nitrogen, and creatinine, respectively. The data were analyzed by one-way repeat measure ANOVA with Bonferroni post hoc test. Orthogonal contrast was used to compare the mean of day 0 with other days post-FMDV. Multiplicity adjusted p-value was calculated to minimize the alpha error.

Figure-3

Thyroxine and lipid profile of calves infected with foot-and-mouth disease virus (FMDV). (a) Changes in the levels of triiodothyronine (T3) during FMDV infection. (b) Changes in the levels of thyroxine (T4) during FMDV infection. (c) Changes in the levels of triglyceride during FMDV infection. (d) Changes in the levels of total cholesterol during FMDV infection. There was a significant increase in the levels of T3 and T4 on 7 days post-infection, associated with a decrease of triglyceride and total cholesterol on 7-14 days post-infection, *p<0.05; **p<0.01; ***p<0.001.

Supplementary Figure-1

Pattern of ECG changes observed in cattle of three different breeds during experimental FMDV infection.

Figure-4

Kinetics of serum cardiac marker creatine kinase-myocardial band (CK-MB) and ECG of foot-and-mouth disease virus (FMDV) infected calves. (a) Temporal level of serum CK-MB during acute FMDV infection. The CK-MB release was significantly low in Malnad Gidda on day 3 post-infection compared to Hallikar and HF crossbred animals. ***p<0.001. (b) Representative electrocardiogram showing interpolated ventricular premature complexes in a HF crossbred calf (indicated by arrow mark) on 3 days post-infection. Sinus rhythm was re-established by 14 days post-infection. (c) Representative electrocardiogram showing increased “ST” duration (0.40 s) in a HF crossbred calf (indicated by horizontal arrow mark) on 3 days post-infection. Sinus rhythm was re-established by 14 days post-infection.

Figure-5

Temporal levels of white blood cell subpopulations in foot-and-mouth disease virus (FMDV) infection in calves. (a) The counts of total leukocytes. (b) The counts of neutrophils. (c) The counts of lymphocytes. (d) The counts of monocytes. A significant decline in the cells was observed during days 7-10 post-FMDV infection. The decline in WBC counts was relatively less in the Malnad Gidda and Hallikar breed calves compared to HF crossbred animals.