27

4 Taking a Toxicologic History

INTRODUCTION

Obtaining a thorough history is critical in effectively treat-ing patients that have been or are suspected of being exposed to a toxic agent. The history - taking process begins from the moment the client walks through the front door of the veterinary hospital or calls in on the telephone. The most important reason for obtaining a thorough history though is to provide the safest and most appropriate care for the patient (Fitzgerald 2006 ). It is the veterinary techni-cian ’ s responsibility to acquire a reliable and accurate history to prevent the loss of money, time, energy, and resources in the hospital setting. This chapter offers guide-lines to assist veterinary technicians in developing the skills necessary to be successful in obtaining a toxicologi-cal history.

PATIENT PRESENTATION

Depending on the circumstances, the technician may not know that the patient has been exposed to a toxic agent upon its presentation to the veterinary hospital. When dealing with toxic exposures the case will refl ect one of four situations: the agent is known and the patient is asymptomatic, the agent is known and the patient is symp-tomatic, the agent is not known and the patient is symp-tomatic (aka “ mystery poisoning ” ), the agent is not known and the patient is asymptomatic. The general history - taking process will be the same for all four cases but may need adjustment according to the current situation at hand.

As with any medical emergency, it is important to be prepared and organized in the event a toxicology case

presents. Some toxicants can act very quickly; therefore, time plays a key role in treatment implementation. Patients that present with clinical signs need to be assessed and stabilized as needed. Identifying ahead of time which staff member will assist in emergent patient care and which will obtain the historical information can save time and confu-sion. Having a predetermined protocol established for toxicological exposures enables the hospital staff to stabi-lize and treat the patients effi ciently and effectively.

MEDICAL RECORD

The medical record for a toxicology case is composed of six sets of required data: client information, patient infor-mation, clinical status, agent information, exposure infor-mation, and implemented treatment. The fi rst three categories are usually a component of any history - taking process, whether a poisoning is involved or not. Agent information, exposure information, and implemented treatment are going to be additional elements. A written protocol can be very helpful in guiding veterinary techni-cians through the history - taking process to avoid over-looking important information relating to a toxicological exposure. Each protocol is going to vary from veterinary hospital to veterinary hospital due to individual prefer-ences, but the six key components of a toxicological history should be incorporated into the protocol and docu-mented in a medical record. Once a written protocol is developed, it should be readily available to everyone in the hospital setting; this will prevent miscommunication when a toxicity case presents.

Small Animal Toxicology Essentials, First Edition. Edited by Robert H. Poppenga, Sharon Gwaltney-Brant.© 2011 John Wiley and Sons, Inc. Published 2011 by John Wiley and Sons, Inc.

Carrie Lohmeyer

28 Section 1 / Fundamentals of Veterinary Clinical Toxicology

cide will not pose a toxic hazard for an 80 lb dog, but the same bar ingested by a 5 lb dog has potential to cause marked clinical signs if treatment is not implemented. Obviously, a current, accurate weight of the patient is criti-cal for calculating doses of active ingredients of toxicants as well as for calculating appropriate medication dosages.

The patient ’ s vaccination status, date of last veterinary visit, current medications and supplements, diet, and pre-existing health conditions can be grouped into the general category of overall health. Knowing the vaccination status of the patient gives the veterinary technician an idea of how well the patient is cared for and may aid in ruling in or out infectious causes of a patient ’ s clinical signs. For example, a 5 - month - old, unvaccinated puppy presents to the veterinary hospital with severe vomiting and diarrhea. A toxicological history was obtained, but the vaccination status of the patient was not asked. According to the owners, the dog ingested a few crystals from a silica gel packet that came out of a shoebox a few hours before the signs began. Silica gel is a minimally toxic agent that may, at worst, cause mild and self - limiting stomach upset. Without knowing that silica gel exposures do not cause serious toxicosis, the assumption may be made that the puppy ’ s signs are related to the ingestion of the silica gel while overlooking a more serious potential cause, such as parvoviral enteritis.

The date of the patient ’ s last veterinary visit also pro-vides information on the patient ’ s prior health care. The prior health of patients that have not been examined by veterinarians for many years is going to be relatively unknown compared to patients that receive regular veteri-nary care. The results of any prior clinical pathology eval-uations may be useful to determine whether any signifi cant changes have occurred that may be attributable to the current exposure. Conversely, the lack of prior clinical pathology information may make it diffi cult to determine whether, for example, an elevation in liver enzyme values is due to the patient ’ s current issue or whether preexisting liver disease is present.

Current medications and preexisting health conditions are two other components of a toxicological history that should not be overlooked. Medications that the patient is taking can infl uence a toxicology case in several ways. Some medications may increase sensitivity to certain toxi-cants. For instance, a dog that is being treated with a nonsteroidal anti - infl ammatory drug for arthritis pain and then ingests ibuprofen may be at a higher risk for the development of gastrointestinal ulcers and acute renal failure. Medications may also infl uence the treatment plan for a given case, because possible interaction of the medi-

Client Information

The fi rst component of any medical record is the client information. This should include the name of client, a billing address, and a telephone number where the client can be reached. If the client is not the owner of the patient (e.g., extended family member or pet sitter), the contact information for both parties should be obtained. When obtaining contact information, it is important to ensure that the record includes all possible means of contacting the client to assure that veterinary staff will be able to com-municate changes in clinical status in a timely fashion.

Patient Information

Patient signalment is the second component of the medical history. The patient ’ s name, breed, age, reproductive status, and weight should all be noted in the medical record. The vaccination status, environment, date of last veterinary visit, current medications and supplements (including dosage), diet, and preexisting health conditions should also be included. Each item of patient signalment has a purpose. Breed identifi cation is important because some breeds can be more or less sensitive to certain agents. A dose of ivermectin considered nontoxic for a Labrador retriever could potentially be problematic for a collie because some collies possess a defective P - glycoprotein in the blood - brain barrier that makes them more sensitive to ivermectin. Similarly, the age of the patient is going to play a role in determining toxicity and recommended treat-ments. Very young or very old patients may have limited organ function, which can infl uence absorption, metabo-lism, and elimination of toxicants. For instance, a dog that is 14 years old may be at higher risk of developing kidney failure from an overdose of naproxen than a healthy 3 - year - old dog ingesting the same dose. The reproductive status of a patient is also an essential element in a toxico-logical history. Pregnant or lactating females exposed to toxic agents may require additional or alternative treat-ment than males or nonpregnant, nonlactating females. The potential effects of the toxicant, as well as any drugs used to treat the toxicosis, on the fetuses must be consid-ered when the case involves a pregnant animal. Some toxicants (e.g., some anticoagulant rodenticides) can be passed to offspring through the milk; an important consid-eration when dealing with lactating animals is whether they have nursed their young subsequent to being exposed to the toxic agent.

The basic tenet of toxicology is “ the dose makes the poison, ” meaning that some exposures will result in no toxic consequences because a toxic dose is not achieved. For instance, a 0.5 oz bar of a 0.01% bromethalin rodenti-

Chapter 4 / Taking a Toxicologic History 29

any toxic exposure that may have occurred and is certain that the dog was not exposed to anything inside the home. When questioned more thoroughly, the owner remembers that the dog was unattended in the yard for approximately 6 hours on the previous day. The owner has a wide variety of plants in the yard as well as occasional mushrooms growing in the grass. The plant varieties in the yard include juniper, sago palm, daffodils, rosebushes, and tulips. From this information, the possibility that the sago palm or a hepatotoxic mushroom may be the cause of the dog ’ s signs must be considered. Without questioning the owner about possible exposures that may have occurred outside the home, the potential exposure to sago palm or mushrooms would have been overlooked.

For indoor animals, information that may be useful includes the areas of the house to which the animal has access, including recent access to areas the pet does not normally go (e.g., attic). The types of medications/herbal products (human and veterinary, prescription, illicit and OTC) in the household, and whether there have been recent visitors who may have dropped medication are important queries to make. It is best to ask for a list of all medications/herbals that are in the household, even if the client is sure that the patient did not have access to it. The types of houseplants in the home should be listed; and it is best to try to obtain the scientifi c name of the plant whenever possible because many different plants share common names. The presence of children or teenagers in the household is important to know, because the young-sters may have left items in the pet ’ s reach or allowed the pet access to a toxicant; sometimes children on medication will feed the medication to a pet to avoid taking it them-selves. The presence of rodenticides or insecticides in the home is an important bit of historical information. Recent redecorating or renovation may expose toxicants (e.g., old bags of rodenticide, lead in paint chips or fl akes) that were not previously accessible to the animal. The presence of other pets and whether the other pets in the house appear normal should also be ascertained.

For outdoor animals confi ned by fences or other means, identifi cation of potentially toxic agents in outbuildings, garages, or sheds to which the pet may have access is important. Other potential hazards found in yards include compost piles, plants, and yard treatments (especially some systemic insecticides and crabgrass killers). For free - roaming animals, the challenge is much greater because the number of potentially toxic agents available is quite large. Determining whether the animal is in an urban, suburban, or rural environment and identifying the nature of the animal ’ s immediate surroundings (e.g., wooded

cation with a drug in a treatment protocol may result in the need to alter the protocol for that patient. Although less common, it is also possible that the patient ’ s clinical signs in a “ mystery poisoning ” are due to an adverse reaction to a prescribed medication. Preexisting health conditions also come into play when deciding what treatment to imple-ment. A patient that has a heart murmur, megaesophagus, or seizure disorder may require different or additional treatment and monitoring than a healthy patient. Decon-tamination is indicated in many exposures to toxicants; however, emesis may be contraindicated in a patient that has a history of seizures, heart problems, or megaesopha-gus. Patients with histories of prior organ dysfunction may be at increased risk from toxicants affecting those organs, and may therefore require more aggressive treatment at lower dosages than would healthy animals.

Clinical Status

Some patients may present to the hospital showing no clinical signs, but signs may have occurred prior to the presentation. Careful questioning of the client can help identify the signs that the patient has developed, when the signs began, and their severity. For example, a 10 lb dog ingested 3 oz of semisweet chocolate approximately 1.5 hours prior to presentation to the veterinary hospital. Upon presentation the dog is BAR and the physical exam is unremarkable. Since the dog is asymptomatic, the veteri-nary staff wishes to initiate treatment by administering a dose of apomorphine to induce emesis. However, the history indicates that the patient had already vomited 5 times at home, recovering a large amount of chocolate. Since the patient has already spontaneously vomited, induction of emesis is not indicated because additional vomiting is unlikely to result in signifi cant further decontamination.

Environmental Information

The environment in which the patient lives is important when identifying possible contributing causes of clinical signs a patient has developed. A domestic animal that is indoor/outdoor or strictly outdoors will have additional opportunities to be exposed to toxic substances, infectious agents, trauma, and other hazards when compared to patients that live strictly indoors. Environmental informa-tion is especially essential in determining the cause of a patient ’ s clinical signs when dealing with an unknown toxicant. For example, a previously healthy 2 - year - old German shepherd presents to a veterinary hospital with severe vomiting and lethargy. Diagnostic testing indicates that the dog is in liver failure. The owner is unaware of

30 Section 1 / Fundamentals of Veterinary Clinical Toxicology

Exposure Information

Once the identity of an agent has been confi rmed, the next step in the history - taking process is to obtain a detailed account of events surrounding the exposure. Knowing only the name of the agent, or the active ingre-dients, may not provide suffi cient information to deter-mine whether an exposure is likely to result in problems for the patient. The veterinary staff needs to have an accurate picture of what occurred before, during, and after the exposure. Information to be documented in the medical record includes amount of the agent ingested (count, volume or weight); physical form of the agent; calculated doses of active ingredients in mg/kg body weight; route, time, and location of the exposure; location of the owner when the exposure occurred; reason that the agent was administered (if applicable); original source of the agent; person(s) responsible for administering the agent (if appli-cable); and potential for other animals to be exposed. Many clients may initially feel they have “ no idea ” as to the amount of toxicant to which the patient may have been exposed, but patient questioning can sometimes help to get an approximation. For medication, if the original prescription amount is known, remaining pills (if any) can be counted out and subtracted from the original pre-scribed amount; calculating the dose taken and the number of days from the time that the prescription was fi lled may enable the veterinary technician to estimate the maximum number of pills that may be missing. For other products (e.g., rodenticide pellets, granulated material, liquids, etc.), information be gleaned by asking how much might be missing from the original and subtracting out a worst - case - scenario amount: “ Complete this question: I know it could not have been more than (blank). ” Narrowing down the amount with questions (i.e., “ Was it as much as a tablespoon? Less? How about a teaspoon? More? Maybe two teaspoons? ” ) can sometimes help to get an idea of how much might have been ingested. When esti-mating in this way it is important to err on the side of caution, so slightly overestimating the amount is better than underestimating.

Other questions to consider for “ mystery poisonings ” include:

How long has it been since the last time the animal appeared normal?

Was the onset of signs gradual or sudden? What was the location of the animal in the last few hours

prior to the development of clinical signs? Is there any history of administration of medications/

herbal products/fl ea or tick control products to this

areas vs. parks and lawns) may help in narrowing down the agents to which the roaming animal may have been exposed. The presence of livestock in the pet ’ s environ-ment should stimulate questioning to determine the pet ’ s access to the barns or feed bins; whether medicated feeds, fl y baits, or feeds with growth promoters (e.g., ionophores) in them are present; whether the livestock have recently been medicated or dewormed; or whether any livestock have recently been euthanized and buried on the property.

Agent Information

The next data set required for the toxicological medical record is the toxic agent, if known. The trade name of the product or medication, active and inactive ingredients, ingredient concentrations, scents or fl avors, EPA registra-tion numbers, and manufacturer contact information should all be documented in the medical record. This information is easy to obtain if the packaging (prescription bottles, containers, boxes, etc.) is brought to the veterinary hospital with the patient. In many cases, clients may not have that information with them because the package may have been ingested, discarded, or destroyed or may never have been available. In some cases it may be necessary to send clients back home or to the store where the agent was purchased to obtain package information. Imprint codes from individual medication tablets or capsules can be used to identify a drug in cases where prescription bottles are not available. A copy of Physician ’ s Desk Ref-erence can help to decipher imprint codes; if a PDR is not available, there is a variety of Internet resources (e.g., drugs.com) to obtain this information, or a poison control center could be contacted. Rodenticide exposures provide excellent examples of why ingredient information is essential. There are three main types of commonly used rodenticides, and each has a different level of toxicity and treatment protocol. Bromethalin exposure and bro-madiolone exposures will not be managed in the same manner, because these rodenticides have different mecha-nisms of action and toxic dosages (bromethalin affects the central nervous system, but bromadiolone inhibits the normal blood coagulation process). Knowing the name brand of the product is often not suffi cient to determine the active ingredient, because products with the same brand name may have different active ingredients (e.g., Rampage ® rodenticide may contain either cholecalciferol or bromethalin as an active ingredient). Rodenticide pellets and bars come in a variety of colors, but, unfor-tunately, there is no way to identify the active ingredient by color or shape.

Chapter 4 / Taking a Toxicologic History 31

owners are unaware of or lack the equipment to accurately obtain these vital statistics.

Another disadvantage to taking a history over the phone is determining the reliability of the owner; indeed, this can often be a challenge when dealing with clients in person. When speaking with a client over the phone, the veterinary technician has to rely solely on verbal communication. Observing a client ’ s body language can at times provide more information about a particular situation than what is communicated verbally. Reliability can be poor due to a number of reasons. Clients may purposely withhold perti-nent information as a result of feeling ashamed that their animal was exposed to a potentially toxic agent, whether by accident or simply due to a lack of knowledge as to what might be toxic. Clients may also feel they might be reprimanded by veterinary professionals for applying a product incorrectly or by attempting to treat a condition at home by giving over - the - counter human medications to their animal. Clients sometimes withhold information merely to avoid having to bring their patients into a vet-erinary hospital due to fi nances or inconvenience. When illicit substances are involved, clients may be reluctant to provide information due to fear of being “ turned in ” to law enforcement by veterinary staff. Tactful questioning and reassurance that the primary concern of the veterinary staff is the well - being of the patient can sometimes help to elicit truthful answers. A gentle reminder that knowing what the toxicant is will allow the patient to be treated much more effectively and cheaply, because knowing the toxicant may well reduce the number of diagnostic tests that may need to be performed. Veterinary technicians should be aware of reasons that client information may be less than accu-rate and use their common sense and instinct to try to determine whether the historical information provided does not seem to fi t the circumstances.

CONCLUSION

It is a veterinary technician ’ s responsibility to provide an accurate history to their veterinarians so that appropriate treatment decisions can be made. Taking an accurate history requires patience and attention to detail. In situa-tions where aggressive patient care is required, it is some-times tempting to skip parts of the history - taking process. However, if details in the history are overlooked, the patient ’ s overall welfare could be compromised, and that key piece of information that could be vital to the case may be overlooked.

animal or other animals in the household in the past 24 hours?

The answers to these questions may assist in narrowing down the possible toxicants to which the patient might have been exposed.

Implemented Treatment

Once the where, how, and why of the exposure is known, the next step for the history - taker is to determine whether the owner had already implemented any treatment at home before calling the vet hospital or bringing the patient into the hospital setting. Implemented treatment may include induction of emesis, bathing the patient for dermal expo-sures, or giving over - the - counter medications to help prevent the development of signs or to treat current signs. Some owners will be knowledgeable about treatment that can be implemented at home, such as inducing emesis. If an owner has already been successful at inducing vomit-ing, this is an important piece of information to note in the medical record. What the owner gave to induce vomiting, how much, when it was given in relation to time of expo-sure, and the results (including what was observed in the vomitus) also need to be documented. In certain instances the agent administered as treatment by an owner can com-plicate the case. For example, salt and syrup of ipecac are sometimes used to induce vomiting at home. Administra-tion of salt can cause serious electrolyte abnormalities, and large doses of syrup of ipecac can cause prolonged gastro-intestinal upset and possible cardiac effects.

TELEPHONE TRIAGE

Some clients may call seeking advice about a toxicologi-cal exposure before bringing the patient into the veterinary hospital. In these cases, having a telephone questionnaire for obtaining a toxicological history may help to determine which patients need to be treated at a veterinary hospital and which patients can be monitored at home. The largest disadvantage to taking a history over the phone is that the clinical status of the patient may be unknown or inaccurate. Unlike when a patient is presented to the hospital, the components of a physical exam cannot be implemented over the phone. To the owner, the patient may look normal, and subtle clinical signs such as mydria-sis or abnormal mucous membrane color can be over-looked. Heart rate, blood pressure, temperature, and respirations are generally unavailable, as many animal

32 Section 1 / Fundamentals of Veterinary Clinical Toxicology

1. The veterinary medical record is composed of basic data sets, including client information, patient signal-ment, and clinical status of the patient. When dealing with a suspected poisoning case, additional data that should be obtained for the medical record include which of the following? a. Agent information b. Exposure history c. Implemented treatments a and b only a, b, and c

2. Patient signalment includes all of the following except: a. Breed b. Age c. Reproductive status d. Vaccination history e. Weight

3. Give three reasons why the patient ’ s age and prior health history are important information to obtain when dealing with a poisoning case.

4. Sparky, a 5 - year - old, neutered male, 12 - pound Jack Russell terrier presents to the emergency clinic with a history of vomiting. According to the owner, Sparky has a habit of “ eating everything within reach, ” but was not witnessed ingesting anything out of the ordi-nary by the owner. In spite of his history of dietary indiscretion, the owner reports that Sparky has never been ill and is current on his vaccination and heart-worm status. What questions that should be asked about Sparky ’ s clinical status?

5. Referring to the patient in Question 4, what questions should be asked about Sparky ’ s environment?

CHAPTER 4 STUDY QUESTIONS

ANSWERS

1.e. All of the listed data should be obtained for the medical record.

2.d. Signalment includes all of the “ personal ” informa-tion on the patient but does not include medical history.

3. Prior medical conditions may affect how the patient is managed (e.g., whether emesis is induced); patients may be more or less susceptible to toxicosis due to age - related differences in response to certain toxicants; medications that the patient is currently taking may alter how the toxi-cant affects the patient.

4. How long has Sparky been vomiting? Have there been any other clinical signs that are not currently apparent? Did he appear lethargic before he began to vomit?

5. Can you please outline Sparky ’ s activities over the 24 - hour period before he became ill? What is Sparky ’ s normal diet and have there been any

recent changes? Have there been any major house-hold changes in the past few days (visitors, reno-vation, etc.)? Is Sparky on any medications, supplements, or herbal products? Is Sparky an indoor or outdoor dog? To what areas of the house, yard, and neighborhood does Sparky have access? Has he been allowed access to any areas that he normally doesn ’ t go? Has Sparky traveled or been boarded in the past week? What type of plants are in Sparky ’ s environment? Have any new weeds or mushrooms been noted in the yard? What type of medications, over - the - counter products, and herbals/supplements are in use in the house? Are there any children in the house; if so, do they have any medications/supplements, paintballs, sugar - free gums, or candies, etc.? Are there other pets in the household; if so, are any of them acting abnor-mally? Does Sparky have access to animals other than household cohorts? Are any rodenticides or insecticides used in the house or yard?

REFERENCE

Fitzgerald KT. 2006 . Taking a toxicological history . In Small Animal Toxicology , 2nd edition , edited by Michael E. Peter-son and Patricia A. Talcott PA , pp. 38 – 44 . St. Louis : Saunders .