The present invention relates to a structurally improved medical injector for animals which includes the following: a fixed body part (100) that includes a main housing (110) in which a housing (110a) and another housing (110b) are combined to form a hollow part, an operating load (120) that is arranged in the hollow part of the main housing (110), and a restoration spring (130) that is located in the main housing (110) and provides restoring force to the operating load (120)； a pressing part (200) that includes a pressing member (210) inserted at the rear of the main housing (110) to be capable of sliding to integrate with the rear of the operating load (120), and a handle (220) formed integrally on the pressing member (210)； a medicinal liquid injection part (300) that includes a medicinal liquid cylinder (320) connected at the front of the main housing (110) to form a medicinal liquid room (321), a piston (330) that is either connected directly to the operating load (120) or is connected to an ancillary load (340) that is combined with the operating load (120) so as to move forward and backward integrated with the operating load (120), and a needle part (310) that is combined at the front of the medicinal liquid cylinder (320) and inserts the medicinal liquid filled in the medicinal liquid room (321) into the body of an animal； and a disinfectant spray part (400) that is combined at the fixed body part (100) and spouts a disinfectant or a color fluid on the external skin surface of the animal.본 발명은 동물용 주사기에 있어서, 일측 하우징편(110a)과 타측 하우징편(110b)이 결합되어 구성된 중공부를 형성하는 메인하우징(110)과, 메인하우징(110)의 중공부에 배치되는 작동로드(120)과, 상기 메인하우징(110) 내에 위치하여 상기 작동로드(120)에 복원력을 제공하는 복원스프링(130), 으로 구성된 고정몸체부(100)와； 상기 메인하우징(110)의 후방에 슬라이딩 가능하게 삽입되어 상기 작동로드(120)의 후단과 일체로 결합하는 가압구(210)와, 상기 가압구(210)에 일체로 형성되는 손잡이(220), 로 구성된 가압부(200)와； 상기 메인하우징(110)의 전측에 결합되어 약액실(321)을 형성하는 약액 실린더(320)와, 상기 작동로드(120)에 직접 또는 상기 작동로드(120)에 결합된 보조로드(340)에 연결되어 작동로드(120)와 함께 일체로 전후진하는 피스톤(330)과, 상기 약액 실린더(320)의 전측에 결합
