of malicious poisoning.Unexplained death(s) has/have occurred.Persistent poor health condition.
Toxicants typically target specific organs or systems (e.g. the cardiovascular, the nervous or the urogenital systems). However, multiple organs can be affected.
If a toxicant targets a specific organ this can help narrow down the differential list.
However, many toxicants target the same organ or system, likely causing similar clinical signs. Therefore, one should not rely on clinical signs alone to make a diagnosis.
Templates can be useful guides for collecting diagnostic information (see Table 2.1), but no template can possibly account for all scenarios. Thus, a thorough, thoughtful and organized investigation is needed without over‐reliance on a template.
Establishing an accurate diagnosis depends heavily on a systematic approach because toxicants often have clinical signs that overlap with other non‐toxicologic causes and lesions may or may not be present.
Even if a poisoning is suspected, the practitioner has to be a neutral observer considering toxic as well as non‐toxic causes of disease. For example, lead poisoning may cause few or very subtle lesions while oak or monensin intoxications cause consistent lesions helpful for making a diagnosis.
The absence of lesions is as important as their presence and is helpful in narrowing down a differentials list.
An accurate diagnosis is central to providing adequate treatment for affected animals and preventing new cases.TABLE 2.1. Checklist for information collection in a suspected poisoning.Owner Data: Date:__________________________________ Owner:________________________________ Manager:______________________________ Address:_______________________________ Phone:______________________________ __ Fax:___________________________________ E‐mail:_________________________________ Health History:Illness past 6 monthsExposure to other animals last 30 daysVaccination historyMedications: sprays, dips, hormones, minerals, wormers past 6 monthsLast exam by a veterinarianPatient Data: Species: __________________________________ Breed:____________________________________ Sex:______________________________________ Pregnancy:_________________________________ Weight:____________________________________ Age:______________________________________ Current Clinical History:Herd size; housingAre other similar groups on the same premises?Common feed or water among groups?Morbidity___________ Mortality _________When first observed sick?How long has problem been in the herd?If found dead, when last seen alive and healthy?Any recent malicious threats?Environmental Data:Location: pasture, woods, dry lot, near river or pond, confined indoors; recent location changesHousing: group‐housed or individually; type of ventilation; new constructionRecent changes in weather, transport, shows or competitions; unexplained deaths; access to trash, old construction materials; recent burning of materialsPesticide use (i.e. insecticides, rodenticides, herbicides) and specific types or names if available (ask for tags or bags to ID)Materials used for construction/renovationServices such as lawn care, pasture seeding, tree planting, and fertilizationAccess to old machinery, automotive products, treated lumber, burn piles, flowing waterDietary Data:Nutritionist (contact information)Diet components: whole grains or ground; sweet feed; pelleted complete feed; other (list)Recent changes in total diet or specific diet component(s)Method of feeding (hand feeding, full feed, mechanical delivery)Type of hay (e.g. grass, alfalfa, mixed; weed contaminants)Presence of molded or spoiled feed or hayPasture: type, scant, abundant, weed contamination; trees or brush presentWater source (flowing stream, pond, well, county or city water)Clinical Signs: Ataxia Salivation Blindness/vision Depression Excitement Seizures Cerebellar signs Dysphonia Other (describe) Anorexia Colic Vomiting Diarrhea Melena Polyphagia Polydipsia Polyuria Dyspnea Lameness Anemia Hemorrhage Hematuria Icterus Hemoglobinuria Methemoglobinemia Straining Fever Weakness Alopecia
A conclusive diagnosis depends heavily on a systematic investigation, appropriate sample choice based on a good knowledge of ADME and appropriate sample handling and storage to preserve specimen integrity.
Discriminating between differential diagnoses may require ancillary diagnostics:Histopathology:Samples for histopathology should be collected in 10% formalin.Bouin’s solution can be used for delicate tissues (i.e. ophthalmic, gastrointestinal and reproductive tissues). Bouin’s solution is not a good fixative for preserving ultrastructure for electron microscopy.Tissues should not exceed 0.5 cm thickness to permit proper fixation. Bloody tissues (i.e. liver and spleen) should be thinner.A set of samples should minimally include liver, kidney, lungs, GI tract and any tissues with lesions.Brain and/or spinal cord are needed if there are neurologic signs.Do not freeze formalin‐preserved tissues.Microbiology:Sterile culture swabs or large sections of any tissues with lesions should be sent fresh (refrigerated, not frozen) for microbial work‐up.Serology/immunology:Whole bloodSerumPlasmaMolecular diagnostics:1 cm square section of fresh (unfixed) tissue with the lesion in a sterile container refrigerated or frozen depending on transport time.Analytical toxicology:Use laboratories accredited by the American Association of Veterinary Laboratory Diagnosticians (AAVLD). These can be accessed at https://www.aavld.org/accredited‐labsFreeze appropriate unfixed tissue specimens for toxicology testing.Use separate containers for each specimen (i.e., do not combine samples into one container). Label each sample.If in doubt, contact the toxicology laboratory for advice on sample types and amounts, including collection and preservation of environmental samples.
Conduct a detailed field investigation to identify, remove and/or restrict access to source(s) of toxicants.
Samples for toxicology fall into three general categories (see Table 2.2):Environmental (e.g. pasture samples, weeds, feed and feed supplements, water, soil, pesticide containers).Antemortem (e.g. whole blood, serum, urine, hair).Postmortem (e.g. stomach contents, liver, kidney, perirenal fat, brain).TABLE 2.2. Samples for toxicology: guide to collection and analysis.Sample Type Amount Condition Potential Analyses EnvironmentalHay, grain, concentrate feeds, mineral supplements500 g to 1 kg compositeIn paper or plastic bags, glass jars; avoid spoilage during shippingPesticides (insecticides, rodenticides, herbicides), heavy metals, salts, feed additives, antibiotics, ionophores, mycotoxins, nitrates, sulfate, cyanide, plant toxins, cantharidin, botulinum toxin, vitaminsPlantsEntire plantPress and dry or refrigerate or freezeIdentification, alkaloids, tannins, grayanotoxins (rhododendron), cardiac glycosides (oleander, foxglove, adonis)MushroomWholeKeep cool and dry in paper bagIdentification; chemical test for amanitinsWater1 LPreserving jarPesticides, salts, heavy metals, microcystins, anatoxin‐a, sulfate, nitrate, pH. For blue green algae identification mix water:10% neutral buffered formalin (50:50) to preserve the cellsSource/bait; soil500 g to 1 kgFreeze in bag or glass jarInclude package label; variety of toxicantsAntemortemWhole blood*5–10 mLEDTA anticoagulantCholinesterase activity, lead, selenium, arsenic, mercury, cyanide, some organic chemicals, anticoagulant rodenticidesSerum*5–10 mLSpin and remove
