Injection systems for animals for veterinary purposes comprising syringes, jet injectors, control units, display units, electronic power assemblies, housings, trigger activated release apparatus, surface contact apparatus to enable firing on contact with patients, safety apparatus to prevent inadvertent firing, injectate reservoirs, orientation apparatus for filling procedure to avoid the introduction of air into the system, electronic selection unit for bottle feed or line feed of injectate into injection chamber, injectate dispensers, electronic energizing apparatus for electronically or mechanically powered injectate apparatuses, injectate capsules, injectate cartridges, holding units for capsules and cartridges, magazines for holding multiple injection cartridges or injection perforators, electronic power packs for storing electrical power for electronic injection assemblies, collapsible bodies for containing injectate, barrels for holding injector capsules, nozzles for injectors, perforators for injectors, needles for injectors, security apparatuses for injectors, piston assemblies for injection units, ram assemblies for injection units, and single and multiple chambers for injection units, all for use in inoculating animals to prevent and cure diseases, to increase the desired output of animals, to reduce pain and trauma for injection procedures, to reduce injection site damage and the associated economic loss, improved efficacy and to improve the health of animals