The first upward deflection is P wave. The two downward deflections are a QS pattern. The middle peak would be r but does not go above baseline so basically a QS pattern. The QS does not necessarily imply that the leads are backwards, this may be the correct pattern in this case. Rats have no detectable T wave. There are plenty of texts and literature reports on normal rat ECG. I am perplexed that you are conducting studies looking at ECG changes when you have not learned what normal is.
I agree with Michael Stonerook on the P wave and QS deflection but T waves are present in rat ECG, ST interval is missing due to the short action potential duration without plateau. I marked the waves in the figure attached. Good luck with your flaxseed experiments, interesting source of PUFA and other compounds.