Systems Affected
All systems have the potential to be affected by toxicants. The GI system, including the liver, is the primary system, with the nervous, renal, and cardiovascular systems also affected. Many toxicants cause clinical signs in more than one system.
Different systems are targeted depending on the inherent toxicity of the specific toxicant. A toxic outcome, however, can be modulated by animal factors (e.g., genetics) or by the dose or the route of exposure, or by environmental conditions such as season, among others.
The effects can occur concurrently, sequentially, or independently of each other.
Some toxicants can have an age predilection, most often related to eating habits (and, therefore, dose ingestion) or to management practices.
Some toxicants have breed or gender predispositions, e.g., reproductive toxicants.
Current or past health problems and treatments may reveal factors that can affect toxicity and influence therapeutic outcomes.
Risk Factors
Risk factors can be due to the toxicant, the individual, or the environment.
Toxicant‐related risk factors include the toxicity of the substance, physical nature (e.g., solid, powdered, nanoparticle), dose, and exposure route (e.g., dermal, oral, inhaled, injected).
Individual risk factors may include age, breed, sex, reproductive status, nutrition, weight, previous health status, and current treatments.
Environmental factors include specific season, drought, floods, ambient temperatures, etc.
Clients may not be forthcoming with complete information if they feel guilty because poisoning resulted from their own mistakes. Conversely, clients may give biased information if they believe poisoning resulted from a faulty product, the negligence of others, or suspected malicious intent.
The clinician should determine how many animals are affected or at risk of poisoning and collect detailed information regarding the current poisoning situation, including clinical signs, date of onset, time of onset, treatment given by the owner, and number of ill and dead animals.
Establishing a conclusive diagnosis of poisoning is like assembling multiple pieces of a giant puzzle. The importance of a complete history, physical examination, and complementary diagnostic tests cannot be overstated.
Steps in diagnosis and formulating a treatment plan are:Determine if signs are a result of an actual poisoning rather than of an infectious, metabolic, or nutritional disease.Determine if signs or lesions are compatible with a toxic exposure. This requires appropriate selection and testing of specimens.Determine if it is an acute or chronic exposure and establish a timeline as treatment will vary.Utilize services available, including an animal poison control center or diagnostic laboratory, to narrow diagnosis (see Appendix 3).
CBC/Serum Chemistry/Urinalysis
These tests are often more helpful in determining the course of treatment, but not in making a diagnosis.
Other Diagnostic Tests
Laboratory confirmation can be made for many toxicants via sample submission to diagnostic laboratories
At a minimum, whole blood, serum, and urine from live animals or liver, kidney, brain, fat, urine, and GI contents from dead animals should also be submitted. Hair, feces, and bone, may be helpful in some cases.
Imaging
Radiographs, ultrasonography, and other modern imaging techniques may help identify foreign objects and/or assess the severity of toxicosis.
Goals
Remove animal from source.
Determine if acute or chronic condition and decontaminate as appropriate.
If it is a life‐threatening situation, immediately provide life support by maintaining respiratory and cardiac function.
Control seizures and tremors as needed.
Provide antidote or antitoxin if available. Most toxicants lack specific antidotes.
The type, duration, and intensity of supportive care coupled with an ideal environment to heal will, on most occasions, determine whether the animal lives or dies.
Supportive and symptomatic care.
Appropriate Health Care
Maintain adequate hydration and control acid–base imbalances if present.
Maintain proper body temperature. Seizures or tremors can result in elevated temperatures. Conversely, severely depressed or comatose animals may have low body temperatures.
Dermal – with a dermal route of exposure, bathe the animal with mild dishwashing detergent. Use personal protective equipment (wearing gloves etc.) to prevent self‐exposure.
Ocular – with an ocular route of exposure, lavage the eye with copious amounts of water or normal saline.
Inhalation – with an inhalation exposure, provide fresh air or humidified oxygen. Be careful to ensure the safety of human workers, especially with smoke, gas, and phosphide intoxications.
Provide sufficient rest to the animal as necessary to allow healing to occur.
Dietary restrictions or additions vary with each toxic incident. Parenteral alimentation may be required in some cases.
Antidotes
Relevant antidotes are discussed in those sections dealing with the specific toxicants, but several important ones are reviewed here.
Very few antidotes exist in medicine, and those that do are generally not approved for veterinary use. Any use associated with non‐veterinary‐approved antidotes is considered extra‐label. The dosages used are often extrapolated from the human literature with very little scientific animal data available. Veterinarians are allowed to legally use medications in an extra‐label manner, but when doing so assume all the responsibility associated with their use.
Little effort has been made by manufacturers to produce antidotes approved for use in veterinary medicine. There is little financial incentive for them to do this as the use of antidotes is limited, making research and manufacturing cost‐prohibitive.