\documentclass{article}
\usepackage[T1]{fontenc}
\begin{document}

\begin{tabular}{|c|c|c|c|c|}	

\hline
\multicolumn{5}{|c|}{\textbf{Animals and friends}}	\\	
\hline
 	&	\multicolumn{2}{|c|}{\emph{Cats}}	&	\multicolumn{2}{|c|}{\emph{Dogs}}	\\	
\hline
 	&	\textsc{John}	&	\textsc{Martha}	&	\textsc{John}	&	\textsc{Martha}	\\	
\hline
\textbf{Black}	&	2	&	5	&	5	&	0	\\	
\hline
\textbf{White}	&	4	&	1	&	0	&	5	\\	
\hline
\textbf{Red}	&	2	&	1	&	\multicolumn{2}{|c|}{Not known}	\\	
\hline
\end{tabular}

\end{document}
