Under USA Copyright laws, even though our clients pay us to take photos of their animals, we the photographers own the copyright to those images. If we could not earn additional money from the subsequent sale of those images to publishers, we would not make sufficient income from photography to pay our bills. In some years the only profit we earn after expenses is from that publishing income. In this way...the price we charge to clients at the shows is actually subsidized by the income we earn from the publishers, and if we could not earn that additional income, we would have to charge significantly more for the photo sessions...thus probably making our prices too high to afford, and significantly curtailing the availability of cat photography at the shows.
We make it a policy to never allow our images in published usages to be used in a degrading or negative manner, and to notify, and obtain further consent from the owners in cases where a photo might be used in a product that we deem might be controversial...pet foods, and pharmaceuticals come to mind as falling in this area....whereas, I would think litter boxes and books about cat breeds would not.....
It is a condition of our employment that we own and can regulate the usage of the images we make, and if any persons have a serious objection to that, they must enter into a "work for hire" arrangement with us prior to commisioning the work. As a rule of thumb, rates for "work for hire" would be 10--20 times more expensive than our normal fees, and those fees are in line with prevailing rates for comparable rights in the photography field.
Many 'free' web site providers, and some software makers, and internet 'print making companies' have clauses in their terms of usage that might grant to them unlimited rights to use any photos you might post using their services. This is usually in the fine print about the usage of their service(s). As the owners of the photos that we make and the copyright claimants to those photos, we do NOT want you to post any of our photos on any site that makes any such condition that would in anyway dilute our exclusive ownership to our images.
We sell and license our images to commercial firms, and if the rights to use or market our photos is granted to another enterprise, this would dilute our capacity to earn income from our work. Should an owner post our photos on such a site, and should we be required to take legal action against that firm/site that used those photos based upon an agreement that our client had entered into with them, it is likely that the firm being sued by us, would end up suing the client who had allowed them to use our photos by agreeing to their business terms and using their 'free' services.
Read the linked article below for further information on "free usage sites".....