Cholecalciferol (Vitamin D3) Toxicity
What is cholecalciferol, and why could it be toxic to pets?
Cholecalciferol is actually the scientific name for Vitamin D3. Vitamin D is needed by your pet's body to help regulate calcium and phosphorous for healthy bones, muscles and nerves. However, an excessive amount of Vitamin D3 can lead to serious health issues and/or poisoning by dangerously altering the metabolism and regulation of the body's calcium and phosphorous levels.
An excessive dose of cholecalciferol is used in possum baits and some rat baits, and large quantities of Vitamin D3 are included in these types of baits as an toxic agent to eradicate these unwanted pest species. In New Zealand, cholecalciferol-based baits are available for possum control, and to a lesser extent against rodents. The cholecalciferol-based baits in pellet/paste formulations are stable in the environment and can remain toxic to pets for at least 12 or more months.
Dogs of all ages are susceptible to cholecalciferol poisoning, with younger dogs and puppies being at higher risk. Cats are thought to be more sensitive to, and succumb more rapidly to cholecalciferol poisoning as compared to dogs.
What are the clinical signs seen with cholecalciferol toxicity?
Symptoms of poisoning generally develop within 12 to 36 hours of ingestion, and varies with the amount of cholecalciferol ingested. Symptoms of poisoning are seen when the the toxic dose of cholecalciferol induces a dangerous rise in calcium and phosphorous levels in the body, leading to a widespread effect across many organs. Toxicity may be seen with the ingestion of as little as 20g of possum bait. Clinical signs of cholecalciferol toxicity include, but are not limited to:-
- Lethargy
- Decrease or loss of appetite
- Nausea - may be seen as excessive drooling
- Vomiting - may have blood in the vomitus
- Diarrhoea or constipation - may have blood in the stools
- +/- altered or increased thirst
- +/- altered or increased urination
- Weakness or incoordination
- Excessive twitching or muscle tremors
- Seizures (convulsions)
- Abdominal pain
How is cholecalciferol toxicity diagnosed?
A full clinical examination by your veterinarian will usually provide several clues that a pet has a ingested a toxic dose of possum/rat bait containing cholecalciferol. The owner's observation of the pet ingesting cholecalciferol-containing bait and/or the presence of the bait being put out on the property also greatly heightens the suspicion of toxicity.
Your veterinarian will likely check your pet's blood calcium, phosphorous, creatinine and urea, as well as performing a urine test (urinalysis) at the first instance. Further blood tests may also be requested by your veterinarian, in order to rule out any other possible causes of the bloody vomit/stools (see also rat bait toxicity), altered thirst/urination (see also ethylene glycol toxicity) and the tremoring/seizures (see also snail/slug bait toxicity). Based on the results of these initial tests, they may open up avenues for other investigations such as electrocardiography (checking the electical activity of the heart) and clotting times, if your veterinarian has further concerns about your pet's condition.
How is cholecalciferol toxicity treated?
There is no specific treatment for cholecalciferol toxicity; however, aggressive symptomatic treatment (treatment directed at managing clinical signs) in the first 24 to 48 hours following ingestion may improve your pet's condition following the poisoning. After fully assessing your pet, your veterinarian may discuss the some or all of the following treatments:-
- Induction of vomiting if less than 2-4 hours has elapsed since the bait ingestion, and if no neurological signs (e.g. seizures, severe muscle tremors) are seen
- +/- Gastric lavage (stomach flush)
- +/- Administration of oral activated charcoal only if no neurological signs are seen
- +/- Administration of oral laxatives only if no neurological signs are seen
- Intravenous fluid therapy
- Use of intravenous medications to induce diuresis (increase urine production to flush out the toxins)
- Control of seizures and severe muscle tremors
- Normalisation of high body temperatures if pet has been seizuring or tremoring excessively
- +/- Medications to lower the excessively high calcium level, as dictated by the blood test results and electrocardiography
- Any other supportive care needed by your pet
As every pet is different and every toxicity case is unique to the individual, your veterinarian will be best placed to tailor a treatment plan for your pet. You can also read more about cholecalciferol toxicity here.
Is cholecalciferol toxicity life-threatening?
Unfortunately, the prognosis (outcome) is generally guarded to very poor with cholecalciferol toxicity, depending on the severity of the poisoning. There is a high chance that residual liver, kidney or heart damage will remain, even if the pet's condition and symptoms have shown improvement from the initial poisoning.
What to do if you suspect your pet has ingested cholecalciferoal-containing bait?
Phone us at 063588675 and request for an emergency consultation, then come down to the clinic as soon as possible. Bring along the packet of bait if you are able to quickly locate it.
The above information is provided for educational purposes only and not intended or implied to be a substitute for professional veterinary medical advice, diagnosis or treatment; and should not be relied on solely as veterinary advice. For more information or if you have any questions, please do not hesitate to call us on 063588675.