Why do the spikes in the electrocardiogram, such as the qrs complex, come shortly before a contraction?

what would it mean if the spikes were irregular?

if you think your dog may have been exposed to a toxin, the best thing to do is to check the label of the item you think your pet ingested. read the information about toxicity. often, but not always, the information on packaging regarding children is relevant to dogs and some manufacturers even discuss dog toxicity. if there is an 800 number on the package – call them! it’s also recommended that you call your veterinarian to confirm the recommendations. if you go to your veterinarian, take all packaging and any information you have on the product.

answer (c) by causing social withdrawal;