General Toxicology & Toxic Plants

Front 1

Any substance that when introduced into a living organism destroys life or injures health.

Back 1

POISON

Front 2

Injury do to high dose or high sensitivity

Back 2

TOXICITY

Front 3

LD50

Back 3

LETHAL DOSE (50)

- Dose which, when given, kills half of the animals it's given to.

Front 4

ED50

Back 4

EFFECTIVE DOSE (50)

- Dose which, when given, effects half of the animals it's given to.

Front 5

LD50/ED50 =

Back 5

THERAPEUTIC INDEX (TI)

- High therapeutic index = safer

e.g. TI = 200 = 200(LD)/1(ED)

- Lower TIs are more dangerous/risky to give and must be very careful when dosing!

Front 6

What are the five basic routes of intoxication? Give examples of common toxins that enter via that route.

Back 6

1. Ingestion

--> food, water source

2. Cutaneous

--> insecticides, topicals like ectoparasiticides & other lipophilic substances (corticosteroids)

3. Inhalation

4. Injection

5. Ocular

Front 7

Describe the typical protocol for treating an animal suspected to be poisoned.

Back 7

1. Stabilize vital signs!

- HR, RR, temps

2. Gather info from owner (but take with grain of salt)

3. Continued absorption of poison is prevented

- e.g. washing out mouth, gastric evacuation/lavage, & adsorbents

4. Elimination of the absorbed poison is attempted

5. Antidote given if available

6. Symptomatic & supportive care is given

Front 8

VPIS

Back 8

Veterinary Poisons Information Service

- Provided by Medical Toxicology and Info Services

- Subscription service provided privately to clinics

Front 9

Aims of VPIS (Veterinary Poisons Information Service)?

Back 9

1. Give info/advice by telephone on management of acute poisoning

2. Provide risk assessment for such cases

- Toxic doses, effects, breed specifics

3. Lab services

4. Referral to 'expert' contacts

5. Identifying tablets/capsules/foreign drugs

6. Antidote/antivenom supply

7. Access to ToxBox

Front 10

What is ToxBox?

Back 10

VPIS in collaboration with VetsNow and consists of:

- Activated Charcoal (slurry)

- Apomorphine (emetic)

- European viper venom antiserum

- Fresh frozen plasma

- Acetylcystine

- Vitamin K1 (treatment of rodent/warfarin poisoning)

Front 11

What are the top 10 most common enquiries to VPIS? (list in order of most common to less common)

Back 11

1. Anticoagulant rodenticides

2. NSAIDs

3. Chocolate

4. Paracetamol

5. Permethrin

6. Metaldehyde

7. Lilie (cats particularly susceptible to)

8. Grapes

9. Benzalkonium chloride (floor cleaners)

10. Adder (snake) bites

Front 12

What are the main areas of the body that can be targeted for triggering emesis in an animal?

Back 12

1. MEDULLA

- Vomiting center

2. MEDULLARY CHEMORECEPTOR TRIGGER ZONE

- Located in the fourth ventricle

3. Vestibular apparatus

4. Stomach

- Vagal & sympathetic afferents from GI tract stimulate trigger zone

5. Small Intestine

- Serotonin is released in GIT

6. Cerebral cortex

Front 13

In order for gastric evacuation to be semi-successive, it must be done within _____ hours of ingestion of toxin.

Back 13

< 2 hours or less depending on the toxin

- Rate of absorption varies depending on what was ingested

Front 14

Gastric evacuation drugs? At home quick tricks?

Back 14

1. 3% Hydrogen peroxide

- Evacuates 30-40% of gut contents, so still a good portion remains.

2. Syrup of ipecac

- Gut irritant and triggers the MCTZ

- Overdose is a risk, so don't dose again if it doesn't work the first time.

3. XYLAZINE (dogs & cats)

- MCTZ effects

4. APOMORPHINE (dogs only)

- Dopamine agonist and effects MCTZ

At home quick tricks:

- Mustard or salt placed on back of tongue triggers the gag reflex!

Front 15

CONTRAINDICATIONS FOR GASTRIC EVACUATION?

Back 15

1. Seizures - risk of aspiration

2. Depression/coma

3. Loss of gag reflex

4. Hypoxia

5. Species that can't vomit naturally (rodents, rabbits, birds and HORSES)

6. Ingestion of corrosives which would irritate the alimentary tract on the way back up

7. Recent abdominal surgery/hernia

Front 16

Describe the protocol of gastric lavaging.

Back 16

1. Provide light anesthesia & cuffed endotracheal tube

2. Tepid water or normal saline is used to flush out the stomach

3. Gravity used for flow to aspirate

4. Repeat until clear

* Keep first lavage in cases where you're not sure of the toxin.

Front 17

Adsorbents? Examples?

Back 17

A material, such as activated charcoal, on which absorption can occur.

- Always given orally!

- No chemical reactions occurring; just absorbing toxic contents which are then excreted in feces with adsorbent.

- E.g. Activated charcoal, Fullers earth (banned in UK)

Front 18

Describe how activated charcoal is made and it's function.

Back 18

ADSORBENT

Activated Charcoal is treated with oxygen to make it very porous, with many holes and cracks, which allow for better absorption of toxins.

- No chemical reactions occurring, just absorbing the toxins and then being excreted in the feces.

* Not good for heavy metal or hydrocarbon poisonings!

Front 19

Catharctics?

Back 19

Substance that accelerates defecation

Examples:

- Sodium (Glaubers salts)

- Magnesium sulphate (Epsom salts)

- Sorbitol = often combined with activated charcoal because charcoal tends to cause slight constipation and this helps keep things moving

Front 20

What methods are possible for enhancing elimination of toxins via urinary tract?

Back 20

1. Acidifying compartments with ammonium chloride

2. Alkalinization with sodium bicarbonate

* Must monitor patient closely for acid/base balance!

Front 21

Function of chelating agents?

Back 21

STRONGLY bind toxic METAL IONS such as lead & mercury.

- Bound ions are chemically inert, preventing poisoning

(unlike with adsorbents which only physically absorb toxins)

Front 22

Most common chelating agent used in vet med?

Back 22

EDTA - Ethylenediaminetetraacetic acid

Front 23

What is the toxic component of chocolate?

Back 23

THEOBROMINE (a methylxanthine)

Front 24

Clinical signs of chocolate (theobromine) toxicity? Treatment?

Back 24

CLINICAL SIGNS:

- Vomiting, excitability, ataxia, and tachycardia

* All common symptoms in most toxicity cases, so getting a good history from owner is crucial!

TREATMENT:

- Decontamination

- Symptomatic treatment

Front 25

List six poisons that have specific antidotes:

Back 25

1. Ethylene glycol

2. Organophosphates

3. Arsenic (mercury)

4. Opiates

5. Paracetamol

6. Warfarin (anticoagulant rodenticides)

Front 26

Main component of antifreeze mixtures.

- Attractive taste & common in cats/dogs with high mortality rate

- Cats much more susceptible than dogs

What type of poisoning is this?

Back 26

ETHYLENE GLYCOL

Front 27

Mechanism of poisoning via ethylene glycol?

Back 27

METABOLITES ARE TOXIC (not ethylene glycol itself)

Ethylene glycol -> converted by Alcohol Dehydrogenase to -> Metabolites

Metabolites include:

- Glycoaldehyde

- Glycolic acid

- Oxalic acid, which form crystals that eventually block up the kidneys = death

Front 28

Ethylene Glycol poisoning early clinical signs? Delayed signs? Treatment?

Back 28

EARLY CLINICAL SIGNS (1-2 hours):

- Weakness, vomiting, incoordination

DELAYED SIGNS (24-96 hours):

- Thirst, anuria (non-passage of urine), hematuria (blood in urine), convulsions, . . . death

TREATMENTS:

1. Ethanol is an alternative substrate to alcohol DH and has a higher affinity for it that ethylene glycol = metabolites of ethylene glycol not produced!

2. 4-methylpyrazole (4MP; Fomepizole) - also binds to alcohol DH; very safe & can be given before confirmation of ethylene glycol poisoning, but problem is it's expensive..

Front 29

Sources of organophosphate poisoning?

Back 29

- Ectoparasitic dips, collars, & powders

- Insecticides

Front 30

Toxicity of organophosphates results in ______________________________________.

Back 30

INHIBITION OF ACETYLCHOLINESTERASE

- Results in build up of Ach in synaptic cleft = overstimulation and saturation of parasympathetic and neuromuscular activity, mainly affecting the muscarinic receptors

- Symptoms: "DUMBLES"

Diarrhea, Urination, Mitosis, Bronchi constriction, Lacrimation, Emesis, Salivation

Front 31

Clinical signs of organophosphate poisoning?

Back 31

"DUMBLES"

Diarrhea, Urination, Mitosis, Bronchi constriction, Lacrimation, Emesis, Salivation

Front 32

Treatment of organophosphate poisoning?

Back 32

Atropine = muscarinic receptor AGONIST

Oximes IV = reactivates the enzyme acetylcholinesterase!

Front 33

Common sources of arsenic (or mercury) poisoning? Common occurrences in animals?

Back 33

SOURCES:

- Inorganic arsenic from weed-killers, insecticides, seed dressing and wood preservatives

- Organic arsenic from growth promoters

OCCURRENCES:

- Ant baits attractive to cats

- Over usage of feed additives

- Cats particularly vulnerable!

Front 34

Mechanism of arsenic (or mercury) poisoning?

Back 34

GENERAL TISSUE POISONING

- Acts on rapidly dividing cells, particularly in the intestines, but also in liver and kidneys

- Results in inactivation of sulphydryl groups on enzymes

- Uncouple oxidative phosphorylation

Front 35

Clinical effects of acute arsenic (or mercury) toxicity? Chronic toxicity?

Back 35

ACUTE TOXICITY (most common in animals)

- Severe gastroenteritis, vomiting, diarrhea... shock

- Massive ulceration and shedding of mucosa = bloody feces and vomit

CHRONIC TOXICITY (organic arsenicals) = nervous signs

- Rare in animals as they typically are exposed to a single, large amount.

- Degeneration of peripheral nerves

- Ataxia, in-coordination, blindness

Front 36

Treatment of arsenic (or mercury) poisoning?

Back 36

GASTROINTESTINAL DECONTAMINATION

Both heavy metals so chelating agents used:

- Sodium thiosulphate = orally or IV

- Dimercaprol = IM

- Broad spectrum antimicrobials as well for animals who've suffered extreme gastroenteritis.

Front 37

Why are cats especially susceptible to paracetamol poisoning?

Back 37

- Deficient in glucuronyl transferase, which is required for glucuronide (metabolic byproduct of paracetamol) conjugation

Front 38

Mechanism of toxicity of paracetomol in animals?

Back 38

"Toxic intermediary" Byproduct of paracetamol oxidizes Hb to metHb!

Front 39

Clinical signs of paracetamol poisoning?

Back 39

1. Facial/pulmonary edema

2. Cyanosis, due to metHb

3. Liver damage

4. Hemolysis

5. Jaundice

Front 40

Treatment of paracetamol poisoning?

Back 40

DECONTAMINATION AND SUPPORTIVE CARE

- N-acetylcysteine makes more glutathione, which binds and gets rid of the toxic intermediary byproduct

- Sodium sulphate

- Vit C converts metHb to oxyHb

Front 41

PARACETAMOL POISONING:

- If caught within _______ hours, there's a good chance of healthy recovery.

- Between _______ hours, recovery likely, but will probably suffer from hepatic damage.

- _______ hours later, prognosis not good.

Back 41

< 8 hours = good recovery

8-24 hours = recover with some hepatic damage

> 24 hours = poor prognosis

Front 42

Sources of anticoagulant rodenticides?

Back 42

1st generation: Warfarin

2nd generation: Difenacoum, bromadiolone (highly toxic)

Front 43

Mechanism of toxicity with anticoagulant rodenticides?

Back 43

- Vitamin K antagonists

- Interferes with production of clotting factors (I, II, VII, IX, X)

Front 44

Clinical signs of anticoagulant rodenticides?

Back 44

- Depression and anorexia

- Vascular collapse (in acute, very high doses)

- Hemorrhage, internal/external (repeated intake) = weakness

Front 45

Diagnosis of anticoagulant rodenticide poisoning?

Back 45

1. Prolonged clotting time

2. Urine analysis

3. PM :(

* Latent period makes rat poisoning difficult to diagnose, so get good history from owner.

Front 46

Treatment of rat poisoning?

Back 46

VITAMIN K1 (not K3)!

Front 47

Very common poisonous plant that's widely distributed in permanent pasture.

- All parts of the plants are poisonous

- Remains poisonous even when dried & stored

- Seeds are parachute type and spread easily.

Back 47

COMMON RAGWORT

- Basal rosette of leaves = most toxic

- Yellow daisy like flowers = May-Oct

Front 48

A farmer may be prosecuted if ragwort is present on his/her pasture.

True or False?

Back 48

TRUE - It's illegal to have on your land.

Front 49

Toxic components of Common Ragwort?

Back 49

PYRROLIZIDINE ALKOLOIDS = HEPATOTOXIC

* Cattle, horses, pigs and chickens are particularly susceptible (especially young)

* Sheep, goats & deer are more tolerant.

Front 50

Symptoms of Ragwort poisoning in cattle? Horses?

Back 50

CATTLE: Poor appetite, either constipation or diarrhea, jaundice, & head pressing

HORSES: Lethargy and yawning (Sleepy Staggers), blindness, walking in circles or long, straight lines

* More often effects are cumulative and chronic exposure is more likely (causes major liver problems)

* Death after acute ingestion may be in a few days.

Front 51

There are NO antidotes to common ragwort poisoning.

True or False?

Back 51

TRUE - so important to remove ragwort from pastures and prevent reinfestations.

Front 52

Leaves and the rhizomes are toxic even when dried.

- Young plant is most toxic

- Mostly cattle affected, but sheep, pigs and horses can be as well.

- Present year round

Back 52

BRACKEN

Front 53

Main toxic components of bracken?

Back 53

1. Thiaminase

2. Carcinogens

3. Cyanogenic glycosides

Front 54

Bracken toxicity causes:

Back 54

1. Bone marrow depletion in ruminants

2. Thiamine deficiency (monogastrates - cattle make their own)

3. Tumors in bladder and GI tract

Front 55

Acute signs of bracken poisoning? Chronic signs?

Back 55

ACUTE:
- Hemorrhagic syndrome (esp cattle)

- Depression weakness

- Anorexia

- Death (4-10d)

CHRONIC:

- Enzootic hematurea = blood in urine (cattle)

- Bright blindness (cattle & sheep)

- GIT Tumors in conjunction with BPV4

- Thiamine deficiency (monogastrates)

Front 56

Clinical features of bracken poisoning in horse? Pigs? Cattle?

Back 56

HORSE = Bracken staggers

PIGS = Appears like heart failure

CATTLE = Weakness, weight loss, bleeding ,blood in feces & breathing difficulties

Front 57

Treatment of bracken poisoning?

Back 57

- Supportive & possible blood transfusion (expensive cattle & sheep)

- Thiamine supplement for pigs and horses

Front 58

- Seasonal (Spring or Autumn)

- Clitocybe species identified to cause problems in dogs.

- DUMBLES Symptoms

- Treated with atropine

Back 58

MYCOTOXINS

Front 59

Evergreen tree with red fruits in Autumn

- All parts poisonous except fleshy, red aril

- Taxines are the toxins, which inhibit Na+ & Ca2+ currents

- Contain irritant oils which are rapidly absorbed

- 60% of poisonings in dogs!

Back 59

YEW POISONING

Front 60

Yew poisoning accounts for ____% of plant poisoning in dogs.

Back 60

60%

Front 61

Symptoms of Yew poisoning in dogs?

Back 61

Vomitting, diarrhea, salivation, hypothermia, bradycardia, respiratory depression, convulsion, heart & respiratory failure

Front 62

Yew poisoning can result in sudden death.

True or False?

Back 62

TRUE - after death PM findings include an empty right heart and the left heart, liver, spleen and lungs filled with dark tarry blood

Front 63

Horses, sheep, cattle and goats are susceptible to yew poisoning along with dogs.

True or False?

Back 63

TRUE

Front 64

Which species are commonly poisoned by Oak? Which parts are toxic? Poisonous compounds? Results in? Symptoms?

Back 64

Cattle, horses, sheep & goats (not pigs)

- Leaves & acorns are toxic

- Tannins = poisonous compounds

- Results in = kidney damage & gastroenteritis

SYMPTOMS:

- Lack of appetite, depression, constipation followed by diarrhea (with blood in feces), blood in urine, colic

Front 65

Poisonous compounds in oak? Antidote?

Back 65

TANNINS = No antidote

Front 66

Onion and garlic poisoning occurs in . . .

Back 66

DOGS & CATS

* Often due to raw, cooked or powdered products being given in leftovers.

Front 67

What types of toxins are found in onions and garlics?

Back 67

Oxidant Toxins - contain thiosulphate

Front 68

Symptoms of onion and garlic poisoning in dogs and cats?

Back 68

-Weakness

-Vomiting

-Diarrhea

-Breathlessness

-Blood in urine

* Eventually results in hemolytic anemia

* Lag time in symptoms = ~2 days

Front 69

Grapes, raisins, sultanas, and currants are all toxic to dogs.

True or False?

Back 69

TRUE

Front 70

Symptoms of grape poisining?

Back 70

Vomiting and diarrhea

* Can result in renal failure and casts in urine

Front 71

Lilies are toxic to __________.

Back 71

CATS

Front 72

Toxic component to Lilies?

Back 72

Calcium oxalate and oxalic acid crystals

Front 73

Symptoms of lily poisoning?

Back 73

- Irritated mucous membranes

- May cause histamine release

- Hypersalivation

- Vomiting

- Diarrhea

- Anorexia

* Seen within 3-6 hours! Quick intervention is key!