Well, dogs excrements seem to be something special. First of all, they will not cause any problem to sewage-treatment facilities, as long as they do not come together with bags. It might rather be a problem to bring the excrements to the toilets because of the stench it may emit during its transport in the house.
To take up the excrements bags should be used or dustpans used exclusively for this purpose due to the bacteria (coli, salmonella, etc.) involved. There are sustainable bags made from corn, etc. However they also should not be put into the toilets because they may block the drain pipe.
Composting dogs excrements is possible, but should not be used in composts used to support plants that will be used as food later. There is a latent risk of transfer of parasites (e.g. tapeworms) which must be avoided. It was also observed that cows and horses refused food being planted on compost with dogs excrements. Being meat-eaters the amino acids in the excrements are taken up from the plants (grass, wheat, etc.) and seem to change the smell or taste of the food. As dogs initially were hunters and marked their territory by excrements this seems to influence other animals still today.
However people growing earthworms seem to love dogs excrements to feed their worms. It seems to be the best food for them since it is soft and can be eaten by the worms easily.
In any case dogs excrements should not be composted or put to the toilets when dogs receive medicine or antibiotics. They influence sewage-treatment facilities negatively and reduce the activity in every compost. They are also bad for worms.
To answer the question. If there is no medicine involved and if nobody in house minds about the smell then taking up dogs excrements with a dustpan and bringing it to the toilet would be the best sustainable solution. All other involve additional material like bags, etc.