Detailed Explanation of Clinical Diagnosis and Prevention and Treatment Methods for Swine Dysentery

Swine dysentery, also known as bloody dysentery, black dysentery, mucohemorrhagic diarrhea, etc., is an intestinal infectious disease unique to pigs caused by Brachyspira hyodysenteriae, characterized by emaciation, diarrhea, and mucous or mucohemorrhagic diarrhea in affected pigs. The pathological features are catarrhal, hemorrhagic, fibrinous or necrotizing typhlitis and colitis.

Clinical key points: The occurrence of this disease has no seasonality, and pigs of all ages can be affected, but it occurs more frequently in piglets aged 2 to 3 months, with high mortality. The disease spreads slowly and lasts a long time. Initially, the acute form predominates, with most affected pigs showing anorexia, severe diarrhea, passing gray soft feces or watery diarrhea, with feces containing large amounts of mucus or blood streaks and blood clots, subsequently containing fresh blood, mucus and fragments of white mucosal fibrinous exudate, with a foul fishy odor. Some affected pigs pass red-and-white alternating gelatinous material or bloody feces, are depressed, have fecal incontinence, arched backs and tucked-up bellies, reduced appetite, increased thirst, weakness and emaciation, and ataxia, finally dying from exhaustion. After 3 weeks, the chronic form predominates, with affected pigs having diarrhea that is sometimes mild and sometimes severe; during diarrhea, the feces contain dark red blood and mucus (like grease), appetite is normal or slightly reduced, the pigs progressively emaciate, become anemic, and show stunted growth, and a small number of recovered pigs relapse after a period of time.

On necropsy, pigs with the acute form show mucous and hemorrhagic inflammation of the large intestine, while pigs with the chronic form show necrotizing colitis, with no obvious changes in other organs.

Key points for prevention and treatment: 1. Adhere to self-breeding and self-raising, and strictly prohibit introducing breeding stock from epidemic areas. 2. Strengthen feeding management, do a good job in cleaning and hygiene, keep pens clean and dry, implement an all-in-all-out system, promptly isolate and treat or cull affected pigs, and properly manage manure and urine treatment in conjunction with disinfection. 3. According to relevant research data, pigs vaccinated with a subunit vaccine containing hemolysin can obtain protective immunity sufficient to prevent the occurrence of clinical symptoms and lesions of swine dysentery. 4. Drug purification. (1) Therapeutic medication. Use 0.5% mequindox for intramuscular injection, at 2 to 5 milliliters per kilogram of body weight per pig; generally piglets are injected with 5 milliliters, growing pigs with 10 milliliters, and finishing pigs with 20 milliliters, injected twice a day for 2 to 3 consecutive days. Gentamicin can also be used at 2000 international units per kilogram of body weight per pig per day, injected twice a day for 5 consecutive days, followed by preventive medication for treatment. (2) Preventive medication. 1. For asymptomatic pigs in the same pen as the affected group. Neomycin sulfate can be used at 0.1 grams per kilogram of body weight per pig per day for 3 to 5 consecutive days. Trimethoprim (TMP) can also be used at 0.02 grams per kilogram of body weight per pig per day for 5 consecutive days as one course of treatment. 2. For presumed healthy groups. Furazolidone can be used at 0.01 grams per kilogram of body weight per pig per day, mixed into feed, for 5 consecutive days. Mequindox can also be used at 5 milligrams per kilogram of body weight per pig per day, mixed into feed, for 5 consecutive days. In addition, carbadox and lincomycin are also effective in treating swine dysentery.