World Veterinarian Quiz 36

INTRODUCTION

• Diagnosis is the evaluation of a patient and the signs and symptoms of a disease or dysfunction to arrive at a cause.
• It allows application of safety measures to correct the effects of poisoning or to arrive at a conclusion to ascertain the cause of poisoning.
• Under field conditions, any disease or ailment, if not diagnosed properly, may be suspected for poisoning when there is sudden death.
• Diagnosis of poisoning is a difficult task and can not be based on a single observation.
• A conformed toxicological diagnosis often rests upon appropriate finding and should take into account the following points.

1. History
2. Circumstantial evidence
3. Clinical signs
4. Pathological evidence
5. Analytical evidence
6. Response to treatment

1. HISTORY

• History often gives important clues about the suspected poisoning.
• Through one should not blindly rely on the history (as it may be corroborated ), yet the owner or attendant of the animal should be thoroughly questioned about the nature and type.

Health history

Current clinical history

Diet/food

Onset of action

Clinical sings

On the basis of health history

• Illness of animal in past 6 months- An animal suffering frequently is less likely to be poisoned than that has become ill recently.
• Vaccination done in recent past- Rule out non toxicological problems by knowing the vaccination status of the animal. If recently vaccination, if not done properly, is likely to produce some adverse reaction
• Type and nature of medication given to animals- recent administration/application of some drug, spray, dip, or anthelmintic, if not carried out

Current clinical history

• Number of animal affected in herd/flock- several animals acutely afflicted at the same time is more suggestive of toxicosis than infectious diseases.
• History of neighborhood problems with animals inexplicably dying may also be explored.
• Animals purchased or home raised- A recently purchased animal may have doubtful history than a home- raised animal.
• Persistence of problem in herd/flock- persistence of disease in the herd is more suggestive of nutritional or management origin than a toxicological problems.

Diet/food

• Type of feed/fodder- animals often prefer good food. Grazing animals generally do not eat toxic plants, unless good forage is available. Recent application of pesticide on the forage crop may likely to harm animals.
• Recent change in diet- change in the diet may suggest sudden alteration in nutritional value. Illness with change in diet is also suggestive of the contamination of diet with some harmful substance. Correlate timing of any change in feed with onset of problem.
• Source of drinking water- presence of algae growth or water from nearby industry may be suggestive of it’s contamination with toxic substances.
• Pesticides recently applied to the grass, grazing land or areas through which water might run off and pass through may contaminate water source and make it unfit for consumption.
• Presence of spoiled or mouldy feed/food- spoiled or mouldy food are source of mycotoxins and hence a source of poisoning.

Onset of action

• Sudden onset of action or signs or sings develop gradually-if animal becomes actually ill in 3-4 hrs, it is more likely to be poisoned than an animal that has been gradually suffering for past few days or weeks.
•  
• Occurrence of vomiting or Diarrhoea before onset of systemic signs- occurrence of nausea, vomiting, or Diarrhoea before onset of systemic sings is often indicative of a systemic substance.
• Many toxicants possess irritant properties and are likely to induce nausea/vomiting by GI irritation before they are absorbed in sufficient amount.

Clinical signs

• Type of clinical signs seen- type and nature of clinical signs observed are important indicator of poisoning in animals.
•  .

2. Circumstantial Evidence

• Circumstantial evidence is an important factor and provides rapid and simple step for diagnosis of poisoning.
• Toxicologist should analyse and correlate the circumstances with the available information.
•  
•  

Housing

• Recently painted house or furniture /equipment may expose animals, particularly pets, to lead and other harmful chemicals in the paint.
• Ingestion of varnish, solvents, cleaners, spot removers and other materials used during painting and polishing of room/furnishers also expose pets to their deleterious effects.
• inadequate ventilation is an important precipitating factor to toxic effect of certain gases like carbondioxide.
• Incomplete combustion of fossil fuels used to warm sheds during winter, particularly in poorly ventilated rooms, is a source of toxic gases.
• Overcrowding of animals aggravate effects of CNS stimulants like amphetamine.
• Overcrowding also disturbs animals and may change their physiological response to external stimuli .
• Location of animal shed near some industry or drainage often exposes animals to various contaminants through air, water and soil.
•  
• Recently sprayed shed/pillars- animals have a tendency to lick or rub their back against pillars/posts.
• Licking of sheds/pillars that are recently sprayed with pesticides is an important source of poisoning in domestic animals.
• The present and previous use of pesticide should be properly seen.

Food and water

• Storage condition- faulty storage of food/feed often leads to contamination of food by mycotoxins and bacteriotoxins.
• The condition of the food should be carefully observed to rule out presence of mycotoxins.
• Where the food is stored or what is stored with it, should be taken in account.
• Water- observe carefully the sanitary/condition of drinking water source.
• Also observe if the pound has been recently sprayed by pesticide for public health purposes.

Environment

• Atmospheric pollution- industrial gases, vapors, and dusts often produce adverse effect on the health of animals.
• Chronic exposure to air pollutants may impair normal respiratory functions and produce respiratory disease.
• Poisonous plants and animals- presence of poisonous plants in the surrounding or movement of snakes around the premises are important source of poisoning.
• These may be taken into consideration while arriving at any diagnosis in case of poisoning.
• Type of soil- some soils are rich in some elements and may lead to poisoning through water or fodder grown on it.
• High level of nitrate/nitrite, arsenic, molybdenum or other heavy metals in water or soil may be responsible for poisoning of animals or birds.

3. Clinical signs

• In this, diagnosis is based on the signs/symptoms shown by living animals or history given by owner, if animal is dead.
• Clinical signs must be used to initiate a search for poisons and should not be used alone for diagnosis.

Central nervous system:

• Convulsion: Ammonium salt, lead, nitrate, cyanide,
• Coma: carbon monoxide, chloral hydrate, nicotine, zinc phosphide, barbiturates, atropine, alcohol, phenol, benzene, turpentine, morphine and its derivatives, hydrogen sulphide
• Ataxia: Bromide, alcohol, hyper tonic and sedatives, OP and carbamate insecticides, thallium

Digestive system:

• Nausea, vomiting and diarrhea: heavy metals like arsenic, barium, chromium, copper, Mercury, iron, zinc and thallium, Strong acid and alkalis chloride chloride acute poisoning, Yellow phosphorus, Selenium acute poisoning, Alcohol, phenol, organophosphorus compound and many plants.
• Constipation: thallium, opioids and oxalate
• Hyper salivation:
• Dry mouth: atropine, Opioids and phenothiazine
• Gastrointestinal bleeding: aspirant causative strong acid and base and oral anticoagulant.

Respiratory system

• Dyspnea: alcohol, hypotonic, sedative, organophosphorus, carbon monoxide, carbamate insecticides, cyanide, hydrogen sulphide, nitrate and nitrite, Sulphur dioxide, zinc phosphide.
• Hyperpnoea: aspirin, methanol, urea and ammonium salt, atropine, herbicides.
• Slow respiration: atropine in a later stage and Selenium
• Pulmonary edema: aspirin, chlorophenoxy herbicides, irritant gases, organic solvent

Skin Hair and nails

• Cyanosis(met hemoglobin):
• Photosensitization: phenothiazine, lantana camara poisoning and many plants
• Alopecia: alkyl sulphide, thallium, X radiation, radium and arsenic
• Staining of skin: Iodine black colour, Bromide brown colour, picric acid yellow colour, Silver Nitrate blue black colour.

Eyes

• Dilation of pupil: belladonna and atropine nicotine in later stage, cocaine, chloroform, hydrogen sulfide and
• Contraction of pupil: opium derivatives like morphine, nicotine in initial stage, other parasympathetic drugs, organophosphorus and carbamate insecticides

Urogenital tract

• Urinary retention: atropine and tricyclic antidepressants, opioids
• Frequent micturition: organophosphorus and carbamate insecticides
• Hemoglobinuria: chronic copper poisoning and chloride
• Colour of urine: phenol and resorcinol dark green colour, picric acid yellow colour, pyrogallol Brown or black colour.

        Body temperature      

• Hypothermia: alcohol, carbon monoxide, sedatives, hypotonic and phenothiazine
• Hyperthermia: organochlorine insecticide, dinitrophenol pesticides, hydroxybenzonitrite herbicides, pentachlorophenol.,

 

Limitations:

• The evidence of toxic signs may not be helpful in all types of poisoning cases, particularly when they are associated with following conditions.
• Different toxicants produce same type of signs or toxicants of same group produce different signs.
• One toxicant is neutralized or potentiated by another toxicants. For eg: alcohol potentiates CNS depressant effect of barbiturate.
• Same toxicants produces different signs in different spieces of animals. For eg: morphine produces CNS depression in most mammals but CNS stimulation in cats.
• Some signs of poisoning (eg vomiting ,seizure ) can also be produced by infectious diseases or metabolic and endocrine disorders.
• The clinician sees only one phase of the progression of the disease. In such cases owner should be asked if he has seen other signs.

4. Pathological evidence

• If the animal dies a through necropsy should be performed and appropriate specimen collected.
• Necropsy findings may provide definite clues to the nature to toxicant in some cases.
• Lesions: presence and lack of lesions should be closely observed.

                            External examination

                            Internal examination

External examination

Odour: A characteristic Odour emanating from the carcass( stomach or rumen content on opening the carcass) may be 1

• For example: bitter almond smell is given by cyanide or benzaldehyde.
• Garlic smell by phosphorus.
• Ammoniacal smell by ammonia or urea.

Skin and mucous membrane: The skin and mucous membrane appearance may be important indication for some types of poisonings.

• For example: skin and mucosa may be jaundiced (pale) in phosphorus.
• Naphthelene and arsine gas intoxication
• Cyanotic (blue brownish-blue colour) in carbon monoxide, nitrite/nitrate, phenacetin & Carbondisulphite poisoning
• Yellow in acute copper poisoning.

Condition of carcass: The condition of carcass is suggestive of some type of poisoning.

• For example: carcass is usually lacerated in cases of extensive convulsion seizures produced by poisons like organochloride insecticides.

Internal examination

• GI tract: should be examined for signs of irritant and corrosive toxicants which are likely to be found in the oesophagus, stomach & intestine.
• Severe gastoenteritis indicates the poisoning may be due to corrosive acids and alkali, salts of heavy metals or irritant plants.
• Stomach and intestinal contents should be examined for abnormal colour( greenish blue colour in copper and black colour in sulphuric acid poisoning)
• Respiratory tract: lesions in the respiratory tract indicates inhalation of irritant gases or volatile liquids.
• Frothing in the lungs may occur due to excessive exudation and struggling as seen in poisoning like ANTU.

OTHER LESIONS :

•  hydrothorax, pulmonary oedema, pneumonia.

Liver and kidney:

•  hepatic and renal lesions indicate the toxicants is irritant in nature, metabolised in liver & excreted via kidney.
• Fatty liver, centrilobular hepatic necrosis may be observed.

Other tissues/organ: 

• common lesions observed – cardiac dilatation, cerebral oedema, haemorrage, meningitis, bony exostoses, changes in glands.

Histopathology:

• Appropriate organs and tissues should be saved in 10% neutral buffered formalin for microscopic examination by pathologist.

5. Analytical evidence

• The imp proof of poisoning lies in the detection of a significant amount of toxic material in the body of animals.

6. Experimental evidence

• Experimental animals may be fed with the suspected food or the toxicant after it is separated from the viscera or signs exhibited are closely observed.
• Example: rabbits to belladonna leaves & pigeons to opium.

7.    Response to treatment

Response to a test dose of specific antidote in an intoxicated animal may confirm a clinical diagnosis.

• For example: clinical improvement (reduce salivation, dyspnea, convulsion etc.)After administration of atropine is an evidence of anticholinesterase (organophosphorus & carbamate insecticides) poisoning.