Cholecalciferol Rodenticide Flashcards
What is the most common source of exposure to this type of rodenticide?
Accidental exposure
**relay or secondary toxicosis is possible, but not really common with this rodenticide
What are other sources of vitamin D that can cause a toxicosis similar to cholecalciferol?
Feed additives, multivitamins, poisonous plants, human psoriasis medications
What is cholecalciferol?
Vitamin D3
it is insoluble in water, soluble in most organic solvents/oil
has no bait shyness
What animals are susceptible to cholecalciferol?
all animals: Cats>dogs
young animals are more sensitive than adults
nursing animals can be exposed through milk
T/F: Cholecalciferol rodenticides cause just a chronic toxicosis
FALSE
can be acute or chronic depending on the preparation and dose
What is the cholecalciferol toxic dose for canines?
0.5 - 20mg/kg
highly toxic
FYI: a 30g pack contains approximately 23mg
Where and how is cholecalciferol absorbed?
absorbed very well in the GI tract bc it is lipid soluble. Can also have storage in adipose tissue
T/F: Cholecalciferol will undergo hepatic recycling
TRUE
that means that patients will need to receive multiple doses of toxiban (activated charcoal) to continue adsorbing
How is Cholecalciferol transported to the liver? What type of metabolism occurs?
Transported via binding to plasma proteins
Metabolized in the liver to 25-hydroxycholecalciferol (CALCIDIOL)
Calcidiol is transported to the kidney and metabolized to 1,25-dihydroxycholecalciferol (CALCITRIOL)
calcitriol is very potent
What metabolite of Cholecalciferol has the highest presence in circulation?
CalciDiol (metabolized in the liver)
Where are the highest concentrations of Cholecalciferol after absorption?
plasma, liver, kidneys, and fat
How is Cholecalciferol excreted?
in bile/feces
can be excreted in milk
can undergo enterohepatic recirculation
What factors can increase the toxicity of Cholecalciferol ?
renal dz, hyperparathyroidism, high calcium/phos in the diet
What is the MOA of Cholecalciferol ?
It causes hypercalcemia and hyperphosphatemia
The body will be “tricked” into thinking there is low Ca - and it will increased absorption and decrease excretion
leads to mineralization throughout the body - ***kidneys, lung, cardiac, vascular walls and stomach –> tissue damage, increased renal loss of sodium and potassium
What hormone will assist in the transformation of calcidiol to calcitriol?
PTH
Calcitriol = active form
What will the PTH levels be like in a patient with Cholecalciferol toxicosis?
Low
When do you see clinical signs associated with Cholecalciferol toxicosis?
within 24-36 hours
takes time for hypercalcemia and hyperphosphatemia to cause mineralization
If you have a patient with Cholecalciferol toxicosis and they have melena and hematemesis, what is their prognosis?
POOR
these are bad prognostic indicators
What clinical signs are associated with Cholecalciferol toxicosis?
GI: anorexia, vomiting (+/- with blood) abdominal pain, constipation, +/- melena
Renal: PU/PD, hyposthenuria
Cardio: arrhythmias, hypertension
Neur: depression, weakness, muscle twitching, sz, coma and death (within days)
What lesions are associated with Cholecalciferol toxicosis?
HGE, mineralization of kidney, myocardium, lungs, stomach, major vessels
*can measure 25-hydroxyvitamin D (calcidiol) or calcium levels in kidney and bile
What abnormalities will you see on the lab work of a patient with Cholecalciferol toxicosis?
Hypercalcemia, hyperphos, elevated calcidiol and calcitriol, decreased PTH
azotemia, proteniuria, glucosuria
Is a chemical analysis often done if you suspect Cholecalciferol poisoning?
No - it’s very expensive and has a long turn around time
but it is good to have for legal purposed etc
Is there a treatment that can correct the mineralization that occurs from Cholecalciferol toxicosis?
NO
need to decrease Ca and Phos to prevent further mineralization - but the damage that has been done is not reversible
What is the decontamination protocol for Cholecalciferol toxicosis?
Emesis (exposure less than 2-6 hrs ago)
Activated charcoal - repeated doses will be necessary
What treatments can be done for a patient with Cholecalciferol toxicosis?
supportive care - IVF, antiemetics, GI protectants, Oral phosphate binders, furosemide, glucocorticoids, sodium bicarb
Salmon calcitonin?
Bisphosphatonates?
Avoid sunlight and decrease Ca/phos in the diet
What is the prognosis of Cholecalciferol toxicosis?
Depends on the severity of the dz at presentation
Better if tx is started before hypercalcemia
Severe hypercalcemia with melena and hem. vomit = poor/grave prognosis
What are your DDX for Cholecalciferol toxicosis?
Things that cause hypercalcemia: Dragon shit
Things that cause PU/PD: diabetes, Cushing’s, Addison’s, renal dz
