When one is concerned about treating intoxications, the primary emphasis should be on prevention, not treatment.
When one is concerned about treating intoxications, the primary emphasis should be on prevention, not treatment. Therefore client education is at the top of the list, whether the client is a producer or an individual animal owner. Client education should emphasize proper chemical handling as well as storage techniques. The attending clinician must remember that toxicants are just another etiology of a disease process and many are capable of mimicking bacterial or viral disease processes.
The case history is very important in diagnosing toxicoses, and the clinician must not allow the client to bias the medical judgement. In many intoxications, it is more important to treat the animal than worry about the diagnosis. (i.e., the diagnosis is important, but saving the animal's life is more important.)
Telephone instructions may be very important to preserve the life of the animal until the client gets the animal to the clinic or until the veterinarian gets to the animal(s) in case of a mobile practitioner. It is important that the client not waste time. The client should be instructed in cases of intoxication as in any emergency situation to protect the animal from injuring itself and protect the people and other animals around. The animal owner should be cautioned to protect him/herself if externally applied chemicals (pesticides) are involved. The client should also be instructed to bring suspect material, with original container, if possible along with any vomitus.
Clean glass containers are best or unused plastic bags. This is especially important if medico-legal aspects are involved. If there will be a time delay, and if the owner is insistent about treating the animal with some "medicationMedication Medication " and if the animal is not sedated, unconscious, etc., then the owner can be advised to: administer milk w/wo egg white, activated charcoal if present, or even water. The owner may be advised to wash dermally exposed animals with soap and water, but the owner(s) should be admonished to use proper precautions to protect themselves.
The owner may be instructed to administer 5 ml. of hydrogen peroxide (1 tsp.) on base of tongue or 1/2 to 1 tsp. of syrup of ipecacIpecac Ipecac , but the owner must be cautioned about vomition as well as toxicity of syrup of ipecac. Again, the owner should bring any vomitus for analysis or medico-legal reasons.
The initial goal of the treatment of intoxicated animals is emergency intervention and prevention of further exposure. This is accomplished by maintaining normal respiratory and cardiac function along with removal of the animal from the toxicant, or the toxicant from the animal. Washing the animal may be of value at this time if the exposure was dermal or local.
Once the animal is stabilized and a adequate history is obtained, the clinician can establish a tentative diagnosis upon which to base rational therapeutic measures. At this time, the clinician can administer specific antidotes or apply remedial measures, delay further absorption if the exposure was oral and hasten the elimination of the absorbed toxicant. Supportive measures and any follow-up therapy may be necessary as long as the animal is exhibiting the detrimental effects of the toxicant.
After the animal arrives at the clinic, the normal primary survey and emergency intervention are completed to maintain the life status of the animal. If the cause of the intoxication is obvious, antidotal procedures may be instituted. Delaying absorption may be accomplished by removing external contaminants via bathing procedures, but personal protective equipment must be used to protect the technician and the veterinarian.
Emesis should be induced if the ingestion occurred within 2-4 hours of ingestion, otherwise this technique is of little value. Apomorphine is the most reliable and most effective emetic. It can be given at dosage rates of 0.04 mg/kg IV or 0.08 mg/kg IM. The disadvantages of apomorphine in humans includes: induction of protracted emesis, and deepening respiratory depression. These effects are not as prominent in dogs and cats as in humans. Apomorphine can be easily reversed by Narcan®NarcanR NarcanR - 0.04 mg/kg.
Other techniques have been recommended have been used but I do not have any faith in most of the others. Xylazine has been used successfully by some clinicians. The contraindications for induction of emesis must be kept in mind. These are: unconsciousness or CNS depression - (respiratory depression), intoxications by petroleum distillates, ingestion of tranquilizers or anti-emetics, more than 2-4 hours since ingestion, and ingestion of acids or alkalis. These latter will weaken the stomach wall, and retching may rupture the stomach or re-injure esophagus and oral cavity. Activated charcoal may be used with emetics to increase the efficiency of both techniques. It is imperative that the vomitus should be saved!!!!!
A gastric lavageGastric Lavage Gastric Lavage should be performed when emesis is contraindicated or the animal is depressed or unconscious. The animal should be placed under light anesthesia with a cuffed endo-tracheal tube extending beyond the teeth. Measure the oral-gastric tube from muzzle to xiphoid cartilage and mark. Ideally, the same sized oral-gastric tube as endotracheal tube (1 mm. = 3 French) should be used (as large as possible) but care must be used when passing the tube through the thoracic inlet and past the base of the heart. Lower head and thorax, slightly and infuse 5 - 10 ml/kg of lavage solution (tepid water) under low pressure for infusion. The infusate may be allowed to return by gravity flow or aspirated from the stomach using a large aspirator bulb or 50 ml syringe.
The cycle should be repeated 10 - 15 times. Activated charcoal should be infused for the last cycle and allow it to remain in the stomach. This will increase the efficiency of the decontamination and the clinician may elect to follow this with a cathartic. It is imperative that the initial lavage sample be retained for analysis. There are several precautions which must be observed in these patients. The operator should use a low pressures and not force the fluid into the tube. A reduced volume should be infused in obviously weakened stomachs. The operator should make sure to not rupture esophageal or gastric walls.
The primary adsorbent used in veterinary medicine is activated charcoalActivated charcoal Activated charcoal . (Note: broken-up charcoal briquets as used for outdoor grilling or the old "Burnt" toastBurnt toast Burnt toast are not effective.) Activated charcoal is available for veterinary use either as activated charcoal and a small amount of kaolin or another product with sorbital, a a mild hyperosmotic cathartic. The optimum dose for small animals is 5 - 10 ml/lb (10-20 ml/kg).
For best results, activated charcoal should be re-administered Q.I.D. for several days following an intoxication. Activated charcoal should not be used with syrup of ipecacSyrup of ipecac Syrup of ipecac , as the syrup reduces the absorptive capability of the activated charcoal. The so-called "Universal Antidote"Universal Antidote Universal Antidote is not effective due the presence of tannic acid. It consisted of activated charcoalActivated charcoal Activated charcoal - 2 parts, magnesium oxideMagnesium oxide Magnesium oxide - 1 part, and tannic acidTannic acid Tannic acid - 1 part
Cathartics containing saline Cathartics Cathartics ( magnesium or sodium sulfateSodium sulfate Sodium sulfate or citrate ) or sorbitol are available for veterinary use. The cathartics may be given simultaneously with activated charcoal or 30 minutes following the administration of the activated charcoal. Multiple dosing with magnesium containing cathartics can lead to CNS depression and multiple use of sorbital can induce fluid pooling in the GI tract and a subsequent dehydration.
The use of mineral oil and/or vegetable oil may be contraindicated in some cases and if used, always followed by a saline cathartic. A colonic lavage or high enema may be used in some circumstances. A whole bowel irrigation technique is being used in humans using large volumes of balanced electrolyte solutions. A polyethylene glycol solution is commonly used in humans for GI surgery or imaging techniques. The clinician should consider whether to use or not use a cathartic in the animal has a toxicant-induced diarrhea or the possibility of bowel obstruction.
Enhanced elimination of absorbed toxicants is attempted to assist the intoxicated animal in returning to normalcy. Once absorbed, a toxicant can only leave the body via the kidney, feces through biliary excretion or lungs if the agent exists in a gaseous state. The kidneys are the easiest to manipulate but requires adequate renal function and will require hydration. The diuretics furosemide (Lasix®Lasix® Lasix® - 5mg/kq, q 6-8 hours) or mannitolMannitol Mannitol (2 gm/kg/hr) may be used to increase urine flow.
Certain toxicants may be excreted more rapidily if the urine pH is manipulated. Many chemicals are weak acids or bases. Degree of ionization depends upon pH of medium and pKa of compound. Some interesting facts about pKa's of compounds are: an acid with low pKa is a strong acid, an acid with high pKa is a weak acid, a base with low pKa is a weak base and a base with high pKa is a strong base. Also, at pH's above the pKa acids are ionized and bases are non-ionized; while at pH's below the pKa,, acids are non-ionized and bases are ionized. Compounds which are unionized at physiologic pH's, could be expected to traverse membranes if the compound is lipid soluble.
The GI tract and the kidney are the organs where we can take advantage of the pH differences using a technique called "ion trapping." Available urinary acidifying agentsUrinary Acidifying Agents Urinary Acidifying Agents are ammonium chlorideAmmonium chloride Ammonium chloride - 200 mg/kg/day in divided doses and physiological saline (PSS or normal saline)(IV). Sodium bicarbonate( 5 meq/kg/hr) may be used as a urinary alkalinizing agent. Urinary pH manipulation should not be used when existing acid-base disturbances exist and might be exacerbated by increased metabolic acidosis or alkalosis.
Peritoneal dialysisPeritoneal Dialysis Peritoneal Dialysis may be used when the kidneys are not functioning properly. In most cases, the procedure is too slow to be clinically important. It is time consuming and there are many pitfalls associated with the technique. It can be used in some instances such as ethylene glycol intoxication where the animal may be kept alive sufficiently long for some renal function to return.
Supportive measures in therapy of intoxications must be kept in the clinicians mind while administering antidotal products and performing various procedures. Good patient monitoring and instituting appropriate symptomatic therapy in mandatory.
Appropriate antidotal therapy is imperative in treating intoxicated animals. The following table lists some available antidotes.
Forensicforensic forensic or medico-legal toxicologymedico-legal toxicology medico-legal toxicology
If you feel that an intoxication or any case in which you are involved may bring about a lawsuit, it is imperative that samples are properly saved and documented along with very good records. (Good clinical or treatment records are a requisite for a good practitioner regardless of whether a case will wind up in court.)
Emergency drugs for intoxications
Drugs used for decontamination
· Activated Charcoal
· Hydrogen Peroxide
· Magnesium Sulfate
· Sodium Sulfate
· Syrup of Ipecac
Drugs used to control seizures or convulsions
· Glyceryl Guaiacolate
· Calcium EDTA
· Deferoxamine mesylate
· Prussian Blue (ferric cyanoferrate)
Other antidotal drugs
· 4-Methyl Pyrazole (fomepizole)
· Ammonium chloride
· Calcium gluconate
· Methylene Blue
· Potassium Chloride
· Sodium Thiosulfate
· Sodium Bicarbonate
· Sodium Nitrite
· Vitamin C
· Vitamin K1
· Whole blood