Hmmm... The truth is
The guy he used the Red horse. There are 2 reasons.

1st : He really don't know why. Or he want to tell lie.

2nd : Damage is not the true reason people use Red horse. The speed of the pet makes this problem. You can read my topic ( http://wlodb.com/topics/17477 ) , and see that SPD of the attackers need to be less than SPD of the pets (or the burst will not be working)
The speed of cows is 32 points.
And I guess he did everythings to decrease his SPD, but it's still larger than 32.
For example, he SPD now is 50 ( >32 ).
While, SPD of Red horse is 62 ( >50 ).
So he will choose Red horse or other pets which has larger SPD in this case.

If you can decrease your SPD to ZERO, no matter what pet you choose.
Because is always less than SPD of every pets (shiba inus, pigs.. or chickens, like Vampire said).

But , I warn you with the cute dog shiba inus :3
They may be gonna die. And if this thing repeats 3 times, you'll get a spawn.
And say bye bye to burst time. :D

P/s : I use tigers :v .
If you see tigers in the burst place. That's me :v