Diagnostic Methods and Prevention Principles for Pig Poisoning

Physiological disorders caused by poisoning can hinder pig growth and development or even cause death, resulting in significant economic losses. Understanding the diagnostic and prevention principles for pig poisoning helps reduce the occurrence of pig poisoning and the losses caused by it.

(1) Diagnosis of pig poisoning

1. History investigation. Understand the types of feed, storage and processing conditions, and analyze whether the feed may be moldy or spoiled; investigate whether the pigs have come into contact with or accidentally ingested toxic plants, rat poison, pesticides, chemical fertilizers, factory wastewater and other toxic substances, and whether recently any drugs have been added to pig feed or drinking water or directly given to pigs for disease prevention, treatment or deworming; understand the number of affected pigs, the time elapsed, the number of deaths and the previous medical history.

2. Clinical examination. Poisoned pig herds often develop the disease at the same time or in succession, with similar symptoms; acute poisoning usually occurs suddenly, and pigs with strong physique and good appetite show more severe symptoms. Depending on the cause of poisoning, affected pigs often show digestive and respiratory symptoms such as vomiting, diarrhea, drooling, anorexia, abdominal pain and difficulty breathing, as well as neurological symptoms such as muscle tremors, movement incoordination, spasms and coma. Some poisoning cases also show symptoms such as anemia, blindness, jaundice, bloody urine, lameness and photosensitivity.

3. Necropsy examination. Pigs are mostly poisoned by ingesting toxic substances through the digestive tract, so examining digestive tract lesions and the color, odor and nature of the contents is of great significance for diagnosis. Affected pigs often show congestion, hemorrhage and necrosis of the digestive tract mucosa. Sometimes toxic plants or other toxic substances causing poisoning can be found in the stomach and intestines; poisoning by some toxic substances can give the gastrointestinal contents a special odor, such as the bitter almond odor of cyanide poisoning and the garlic odor of phosphorus poisoning; the vomitus and gastric contents in zinc phosphide poisoning may show fluorescence in the dark. The liver, kidneys and other organs often have damaging lesions. In addition, changes in blood color are meaningful for diagnosing poisoning by certain toxic substances, such as bright red blood in cyanide poisoning and brown blood in nitrite poisoning.

4. Submission of toxic substances for testing. For cases initially diagnosed as poisoning but in which the toxic substance cannot be determined, an appropriate amount of feed or fresh gastrointestinal contents should be taken for laboratory analysis.

(2) Prevention of pig poisoning

1. Prevent nitrite poisoning: green feed such as cabbage, lettuce and radish leaves is best fed raw or after pulping. If boiling, cool it quickly, do not cover and stew it, and do not leave it in the pot overnight or seal it in a vat while hot. Green feed stored temporarily should be spread out in a dry, cool and well-ventilated place; green feed that has become hot and moldy after piling should not be used to feed pigs.

2. Prevent solanine poisoning: potatoes should be stored in a dry, cool place to prevent sprouting; do not feed pigs rotten, green or sprouted potatoes, and when necessary, first remove the sprouts, green skin and rotten parts, cook thoroughly (a certain amount of vinegar may be added), and then feed in combination with other feed. Do not feed pigs dropped green tomatoes directly; they may be heated with an appropriate amount of vinegar and then fed. Piglets and pregnant sows should not be fed rotten potatoes or green tomatoes as feed.

3. Prevent mycotoxin poisoning: feed such as corn, wheat, rice and feed legumes should be stored in a low-temperature, dry place; severely moldy feed should be discarded, and slightly moldy feed should be peeled or soaked to reduce toxicity before being mixed with other feed; do not feed pigs moldy sweet potato, and when necessary, remove the moldy parts, cook them thoroughly, and then use them in combination with other feed. Do not use moldy rice straw as bedding material in pig pens.

4. Prevent poisoning from cakes, meals, distillers grains and residues: cottonseed cake (meal) and rapeseed cake (meal) should be detoxified before use and used in limited amounts; distillers grains, tofu residue and the like should not be stored too long, and residues alone should not be used to feed pigs; severely spoiled ones should be discarded.

5. Prevent salt poisoning: master the amount of salt added to feed (the salt content in feed generally should not exceed 0.5%), ensure sufficient drinking water, and when using sauce residue, soy sauce residue, pickled vegetable juice, salted fish meal and leftovers to feed pigs, consider their salt content and mix them with other feed, adding no salt or less salt. When using sodium sulfate or sodium lactate to treat pig diseases, do not use excessive amounts.

6. Prevent poisoning from toxic plants: do not use water dropwort, oak leaves, lamb's quarters, buckwheat seedlings, sorghum seedlings, cocklebur seed cake and the like as feed for pigs; do not plant trees such as chinaberry and apricot beside pens, to prevent their fruits from falling into the pig pens; remove plants such as cocklebur, oak and datura around the pens to prevent free-ranging pigs from accidentally eating the stems and leaves of these plants.

7. Prevent pesticide and rat poison poisoning: strengthen the management of pesticides and rat poisons, and strictly prevent contamination of feed and drinking water; do not feed pigs green feed that has just been sprayed with pesticides, and green feed sprayed with pesticides some time ago should be washed multiple times before use; when killing rats, poison bait should be placed in a safe place.

8. Prevent drug poisoning: when using deworming drugs to deworm pigs, or using drugs such as olaquindox and oxytetracycline to prevent and treat pig diseases, master the dosage and administration method, and do not overdose or use drugs for a long time.

In addition, attention should be paid to the management of chemical fertilizers, heavy metals and chemical reagents to prevent contamination of feed and drinking water or accidental ingestion by pigs.

(3) Treatment of pig poisoning

1. Remove the source of poison: promptly collect and destroy suspicious poison bait, vomitus, garbage or feed to prevent pigs from continuing to contact or eat them. If the toxic substance has not yet been determined, consider changing the location, drinking water, feed and utensils.

2. Remove poisons from the body surface: if poisoning occurs due to body surface contact with toxic substances, choose clear water, soapy water, lime water or vinegar water according to the properties of the toxic substance and repeatedly wash the body surface to remove poisons from the body surface.

3. Remove poisons from the digestive tract: for poisoning caused by ingestion of toxic substances through the digestive tract, emetics, gastric lavage agents, purgatives and adsorbents may be used to promote the discharge of toxic substances and prevent their absorption by the body.

Emetics can excite the vomiting center and promote the discharge of toxic substances through vomiting. The commonly used emetic is 1% copper sulfate solution; ipecac powder or ipecac syrup may also be used.

For toxic substances that enter the body through the digestive tract, gastric lavage is an effective method of removing them. Commonly used gastric lavage agents include warm water, 1%-2% saline and physiological saline; depending on the properties of the toxic substance, 1% tannic acid solution, 0.02%-0.1% potassium permanganate solution, 2% sodium bicarbonate solution and the like may also be selected. Gastric lavage agents are more effective when applied within 4-6 hours after the toxic substance enters the digestive tract.

Purgatives include saline and oil purgatives, which can promote the discharge of toxic substances by strengthening gastrointestinal secretion and exciting intestinal peristalsis. Saline purgatives, due to their osmotic pressure effect, can prevent absorption of toxic substances and have a relatively good detoxifying effect; the commonly used agents are sodium sulfate and magnesium sulfate. Oil purgatives can dissolve certain toxic substances and promote their absorption, so they are generally not used as detoxifying purgatives, especially not for poisoning by toxic substances such as organophosphorus, organochlorine and zinc phosphide.

4. Bloodletting: for cases in which the toxic substance has been in the body for a relatively long time and has been absorbed into the blood, venous bloodletting or bloodletting therapies such as ear clipping and tail docking may be used to remove part of the toxic substance, followed by intravenous injection of an appropriate amount of glucose or glucose saline.

5. Use specific antidotes: when the nature of the toxic substance is determined, for certain poisonings that have specific antidotes, specific antidotes should be used promptly for detoxification treatment. Organophosphorus poisoning can be detoxified with pralidoxime iodide or atropine, nitrite poisoning with methylene blue or toluidine blue, cyanide poisoning with sodium thiosulfate or sodium nitrite, organic fluorine poisoning with acetamide, and poisoning by heavy metals (mercury, lead, copper, etc.) and metalloids (arsenic, antimony, phosphorus, etc.) with dimercaprol or sodium dimercaptopropanesulfonate.

6. Symptomatic and supportive therapy: after poisoning by certain toxic substances, there may be no specific antidote or no specific antidote available for purchase, so symptomatic and supportive therapy is often used to maintain the body's vital activities and relieve poisoning symptoms. Commonly used symptomatic and supportive therapies include cardiac stimulation, fluid replacement, sedation, respiratory stimulation, diuresis and liver protection.