Ivermectin

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Ivermectin
• Worm medication used orally and
parenterally in most species (Heartguard,
Ivomec, Eqvalen, Zimecterin)
• Cumulative toxicant
• Young animals more susceptible
• Often a problem in dogs given horse paste
Ivermectin
• Dogs-6ug/kg =heartworm preventive dose;
• 2.5 mg/kg PO =mydriasis, 5mg/kg PO= muscle
tremors, 40 mg/kg PO= death
• Collies, Aust. Shepherd, Shelties, Border Collies0.1 -0.2 mg/kg PO or SC causes toxicity and death
• Cats-0.5mg/kg=mydriasis and tremors
• Equine-2mg/kg=ataxia and blindness
• Cattle and Sheep-4mg/kg=ataxia/death
Ivermectin
• Mechanism of action is to increase GABA release,
affinity of GABA receptor and direct GABA
agonist
• Onset time is hours to 1 day, affects CNS
• Clinical signs-hypersalivation (dogs), tremors,
bradycardia, convulsions, coma, mydriasis,
blindness, ataxia
• Can see anaphylactic reactions in dogs
• No visible lesions
Ivermectin
Diagnosis
• History of administration
• Brain ivermectin concentration >100ppb
Treatment
• Short acting barbiturate for convulsions (no benzos)
• IV physostigmine (0.04mg/kg) BID in comatose
animals
• Flumanezil and moxidectin-expt. Benzo antagonists
• Epinephrine, fluids for anaphylaxis
Household Cleaners
• Product warning label indicates level of
toxicity
–
–
–
–
No label = LD50 > 5 g/kg
Caution = 0.5 – 5 g/kg
Warning = 50 – 500 mg/kg
Danger: Poison = <50 mg/kg
Soaps, Shampoos, Detergents
• Most have low toxicity
• Usually cause only vomiting and diarrhea
• Cationic surfactants are found in contact lens
solutions, fabric softeners, swimming pool
algicides; can cause neuromuscular and ganglionic
blockade as well as GI ulcerations, acidosis and
shock
• Anionic surfactants are in many cleaning products
like shampoos have the potential to cause
hemolysis
Disinfectant Cleaners
• Products like Lysol contain phenolic compounds
mixed with detergents
• Pine oil based compounds like Pine Sol
• These products are especially toxic to cats due to
metabolism by glucuronidation; can cause liver
injury, jaundice, and renal damage in conjunction
with GI problems
• Phenolics also found in creosote and tar paper;
watch out for pigs
Alkaline Compounds
• Ammonia, Oven Cleaner, Most Drain Openers
• All have pH of >12 which can cause burns (ulcerations)
• Ulcers can be very severe, especially with granular drain
openers
• Ingestions causes GI ulcerations, vomiting, salivation,
dysphagia (esophageal stricture), dyspnea
• Bleach and scouring powders with bleach usually not high
enough pH to cause ulceration; can be a problem if mixed
with ammonia = chloramine gas
Acidic Compounds
• Toilet bowl cleaners, concrete cleaner,
Lime-A-Way, some drain openers
• Can cause severe burns, but usually not as
deep as alkali
• Signs and treatment similar to alkaline
products
Treating Household Cleaner Ingestions
• If a potentially toxic amount of a noncorrosive compound ingested, emesis
should be induced; no activated charcoal
unless systemic effects are expected
• For corrosive compounds 1) dilute with
milk or water, 2) determine exactly how
much of what material was ingested
Treating Toxic Corrosive
Ingestions
• If there is pain, dysphagia, excessive
drooling, or ulceration and the exposure was
potentially toxic:
– Establish airway and get esophagoscopy
– If esophagus can’t be examined quickly, start
corticosteroids
– If examination indicates burns, give
corticosteroids
– Symptomatic and supportive care
Drano Ingestion – Initial Visit
Drano Ingestion – Final Visit
Petroleum Products
• Gasoline, mineral spirits, kerosene, lighter
fluid, nail polish remover, solvents, motor
oil, furniture polish
• Biggest worry is aspiration causing
hydrocarbon pneumonia
• Pneumonia risk related to viscosity; less
viscous = more toxic
Systemic Toxicity of
Hydrocarbons
• Most hydrocarbons are CNS depressants
• Some volatile hydrocarbons sensitize the
heart to catecholamines and can cause
sudden death due to cardiac arrest
• Many hydrocarbons cause dermal irritation
and hair loss
Signs of Hydrocarbon Toxicity
• Depression, lethargy, ataxia, seizures, coma
• Dyspnea, coughing, wheezing, X-ray
changes in lungs with pneumonia
– Spontaneous vomiting and aspiration often
occurs with more volatile compounds
Treating Hydrocarbon Ingestions
• Wash for dermal exposures
• Do not try to increase viscosity by adding
heavier compound
• Do not induce emesis unless a large, life
threatening ingestion (>1 ml/kg)
• Monitor for pneumonia; treat with
antibiotics if present
Oak (Acorn) Poisoning
• Red Oak are most toxic due to high tannins, Live
Oak is questionable
• problems are seasonal, usually in fall after a storm
or during summer droughts
• primarily affects cattle; calves are more
susceptible
• Toxic priniciple is thought to tannins or their
metabolites
• Animals must consume large amounts of acorns or
buds to be toxic
Oak poisoning
• Cases have relatively low morbidity with
moderate mortality (35-80%)
• Animals usually ingested acorns for 1 week prior
to signs
• Symptoms are primarily renal and GI-anorexia,
depression, weakness and possible nasal
discharge; progresses to rumen atony, black tarry
diarrhea, ventral edema, dehydration.
• terminal animals are often recumbent near water
Cyanogenetic Plants
• Wild and choke cherry, Sudan and Johnson
grass, Flax, Sugar beet tops, Arrow grass
• contain glycosides with cyanide groups
Thiaminases
• Horsetails and Bracken Ferns
• Thiaminases destroy thiamine causing
neurological problems; causes aplastic
anemia in ruminants
• Primarily affects horses and ruminants
• Usually occurs if other forage is inadequate
Bracken Fern
Calcium Oxalate plants
• Members of Araceae family contain calcium
oxalates; Dieffenbachia (Dumb Cane),
Philodendron, Elephant ear, Calla lily, Arum lily,
Caladium
• All parts of plant are toxic; stalk more toxic than
leaves
• Usually occurs in cats, dogs, birds, and lizards
• Rarely life-threatening
Calcium Oxalate plants
• Preformed calcium oxalate crystals embed in all
parts of GI tract; also contain proteolytic enzymes
that cause histamine release
• Onset time is immediate; primarily affects GI
system
• Clinical signs include head shaking, salivation,
dyspnea, vomiting, diarrhea, loss of voice
Calcium Oxalate plants
• Diagnosis is by history of exposure and
compatible clinical signs
• Treatment
•
•
•
•
Rinse mouth with water
Anithistamines for dyspnea
Demulcents (Kao-pectate; no Pepto in cats)
Fluids for severe vomiting and diarrhea
Precatory Bean; Rosary Pea
• Grows in Carribean
• Commonly sold as rosary “beads”
• Extremely toxic, 1 pea can kill a child or
dog
• Severe enteritis leads to shock
Castor Bean
• Common plant in S. Florida
• Mole plant
• Seeds are extremely toxic due to ricin
Oleander
• Contains cardiac glycosides (much like
digitalis)
• Highly toxic
Cassia
• Coffeeweed, sicklepod
• Causes muscle degeneration
Crotalaria
• Rattlebox
• Causes liver injury
Cycas and Zamia
• Sago Palms, Coontie Plants
• Seeds are especially toxic
• Causes liver injury
Sesbania
• Seeds are most toxic part
• Produce severe hemorrhagic or necrotic
enteritis
Cestrum
• Day and night blooming jessamine
• Contains Vitamin D
• Kidney damage
Lantana
• Causes photosensitization secondary to liver
injury
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