What are the eight major categories of veterinary drugs?

　　I. Antimicrobial Agents

　　Primarily used for the treatment of microbial infections caused by bacteria, viruses, and other microorganisms—for example, penicillin derivatives (such as ampicillin) and cephalosporins (such as ceftiofur). Misuse may lead to increased antimicrobial resistance; therefore, they should be used strictly according to veterinary guidance.

　　II. Antiparasitic Drugs

　　For both internal and external parasites, such as ivermectin (for nematodes) and albendazole (for tapeworms), the dosage of certain medications needs to be adjusted according to the specific type of parasite to avoid drug residues in animals.

　　III. Central Nervous System Drugs

　　Contains a sedative (such as diazepam) and an analgesic (such as flunixin meglumine). Clinically, it is commonly used for animal anesthesia or postoperative pain management.

　　IV. Drugs for the Reproductive System

　　Contains oxytocin (promotes labor) and prostaglandins (induces estrus). Improper use can easily trigger miscarriage, so the timing of administration must be precisely controlled.

　　V. Metabolic Modulating Drugs

　　Includes vitamins (such as vitamin D3) and electrolytes (such as calcium gluconate). It is commonly used in livestock farms to prevent nutritional deficiencies or postpartum paralysis.

　　VI. Disinfectants and Antiseptics

　　Such as povidone-iodine (for environmental disinfection) and benzalkonium bromide (for instrument sterilization). It is necessary to rotate the types periodically to prevent pathogens from developing drug resistance.

　　7. Antidote

　　Used for emergency treatment of pesticide or heavy-metal poisoning—for example, dimercaprol (for arsenic poisoning) and atropine (for organophosphate poisoning). It is highly time-sensitive and must be administered as soon as possible.

　　VIII. Other Types of Drugs

　　Includes antihistamines (such as promethazine) and hemostatic agents (such as vitamin K3). Classification is based on the diversity of pharmacological effects; selection should be made in conjunction with specific symptoms.