For phage therapy, phage dose is calculated on the basis of bacterial burden, i.e MOI based dose. If you have any confusion feel free to contact.

it's general for every animal? does not depend on animal weight etc? I have read in some paper they used dose per kg of animal weight

Phage dosage depend how is phage administrated. As you may know phage preparation are sold on 10ml, 20ml and 100 ml multiple doses. In general this phages preapration have a concentration of E5. When phages are applied oraly stomach acid neutralisation is recomended. 10 or 20 ml are use as a single dose twice daily. On infected wound phages are applied depending on the surface of the wound as a spray or washing. In case of erupted apendicities 100 ml phages preparation is inserted in abdomen after the apendictomy. In furunculus ans carbuncules after eruption they are washed with phage preparation.

They are several papers about phage therapy that can be used as a model.

Also a lot will depend on phage characteristics. Phages with high burst rate, good killing properties, short latent period and less BIMs will work even in low concentrations and low dosage. Phage therapy is "state of art".