Pam,

Short answer is yes they can. Kennel Cough is a good example
of a problem caused by a virus. There are a lot of others. Poor
Riley. Hope he is feeling better soon. Do Bella & Ripley act pretty
normal(except for the skipping breakfast) ? Are they both drinking
water as normal? I'd just watch them for 24/48 hours & see how
things go. Give hugs to your furkids for me.