Cholecalciferol Rodenticide

Question 1

What is the most common source of exposure to this type of rodenticide?

Answer 1

Accidental exposure

**relay or secondary toxicosis is possible, but not really common with this rodenticide

Question 2

What are other sources of vitamin D that can cause a toxicosis similar to cholecalciferol?

Answer 2

Feed additives, multivitamins, poisonous plants, human psoriasis medications

Question 3

What is cholecalciferol?

Answer 3

Vitamin D3

it is insoluble in water, soluble in most organic solvents/oil

has no bait shyness

Question 4

What animals are susceptible to cholecalciferol?

Answer 4

all animals: Cats>dogs

young animals are more sensitive than adults

nursing animals can be exposed through milk

Question 5

T/F: Cholecalciferol rodenticides cause just a chronic toxicosis

Answer 5

FALSE

can be acute or chronic depending on the preparation and dose

Question 6

What is the cholecalciferol toxic dose for canines?

Answer 6

0.5 - 20mg/kg

highly toxic

FYI: a 30g pack contains approximately 23mg

Question 7

Where and how is cholecalciferol absorbed?

Answer 7

absorbed very well in the GI tract bc it is lipid soluble. Can also have storage in adipose tissue

Question 8

T/F: Cholecalciferol will undergo hepatic recycling

Answer 8

TRUE

that means that patients will need to receive multiple doses of toxiban (activated charcoal) to continue adsorbing

Question 9

How is Cholecalciferol transported to the liver? What type of metabolism occurs?

Answer 9

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

Question 10

What metabolite of Cholecalciferol has the highest presence in circulation?

Answer 10

CalciDiol (metabolized in the liver)

Question 11

Where are the highest concentrations of Cholecalciferol after absorption?

Answer 11

plasma, liver, kidneys, and fat

Question 12

How is Cholecalciferol excreted?

Answer 12

in bile/feces
can be excreted in milk
can undergo enterohepatic recirculation

Question 13

What factors can increase the toxicity of Cholecalciferol ?

Answer 13

renal dz, hyperparathyroidism, high calcium/phos in the diet

Question 14

What is the MOA of Cholecalciferol ?

Answer 14

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

Question 15

What hormone will assist in the transformation of calcidiol to calcitriol?

Answer 15

PTH

Calcitriol = active form

Question 16

What will the PTH levels be like in a patient with Cholecalciferol toxicosis?

Answer 16

Low

Question 17

When do you see clinical signs associated with Cholecalciferol toxicosis?

Answer 17

within 24-36 hours

takes time for hypercalcemia and hyperphosphatemia to cause mineralization

Question 18

If you have a patient with Cholecalciferol toxicosis and they have melena and hematemesis, what is their prognosis?

Answer 18

POOR

these are bad prognostic indicators

Question 19

What clinical signs are associated with Cholecalciferol toxicosis?

Answer 19

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)

Question 20

What lesions are associated with Cholecalciferol toxicosis?

Answer 20

HGE, mineralization of kidney, myocardium, lungs, stomach, major vessels

*can measure 25-hydroxyvitamin D (calcidiol) or calcium levels in kidney and bile

Question 21

What abnormalities will you see on the lab work of a patient with Cholecalciferol toxicosis?

Answer 21

Hypercalcemia, hyperphos, elevated calcidiol and calcitriol, decreased PTH

azotemia, proteniuria, glucosuria

Question 22

Is a chemical analysis often done if you suspect Cholecalciferol poisoning?

Answer 22

No - it’s very expensive and has a long turn around time

but it is good to have for legal purposed etc

Question 23

Is there a treatment that can correct the mineralization that occurs from Cholecalciferol toxicosis?

Answer 23

NO

need to decrease Ca and Phos to prevent further mineralization - but the damage that has been done is not reversible

Question 24

What is the decontamination protocol for Cholecalciferol toxicosis?

Answer 24

Emesis (exposure less than 2-6 hrs ago)

Activated charcoal - repeated doses will be necessary

Question 25

What treatments can be done for a patient with Cholecalciferol toxicosis?

Answer 25

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

Question 26

What is the prognosis of Cholecalciferol toxicosis?

Answer 26

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

Question 27

What are your DDX for Cholecalciferol toxicosis?

Answer 27

Things that cause hypercalcemia: Dragon shit

Things that cause PU/PD: diabetes, Cushing’s, Addison’s, renal dz