Cholecalciferol Poisoning in Dogs

Although vitamin D supplements may be good for your dog’s heart if necessary, it is important to know that having too much is just as bad, if not worse. There are several vitamins that have vitamin D, including multivitamins, omega fatty acid supplements, prescription vitamins, calcium, and vitamin D-3. Just a small amount of vitamin D made for humans can cause cholecalciferol poisoning in dogs. In fact, it only takes one milligram per pound of body weight to cause symptoms, and it can be fatal at just four milligrams per pound of body weight. That means just one multivitamin, which contains an average of 25 milligrams of vitamin D, can be fatal for a 5-pound dog. Therefore, it is best to keep these and all other medications out of the reach of your dog.

Most dog foods and treats contain more than enough vitamin D, so there is no need for vitamin supplements unless your veterinarian suggests it if your dog has a deficiency. This vitamin (like others) is absorbed just like fats get absorbed into your dog’s body, being stored in the liver. When there is too much vitamin D (cholecalciferol) in the liver, it triggers the metabolic changes that mineralize the tissues and organs. This is a life-threatening emergency that can be lethal if not treated within the first 24 to 36 hours.

The ingestion of too much vitamin D from vitamins (calcium, multivitamins) can cause cholecalciferol poisoning, which creates an imbalance in your dog’s electrolyte system by increasing calcium levels (hypercalcemia) and phosphorus levels (hyperphosphatemia). Cholecalciferol poisoning from vitamins that contain vitamin D can also cause heart irregularities, kidney injury, muscle damage, electrolyte imbalance extremely high blood pressure, and depression of the central nervous system. In addition, mineralization of the muscles, kidneys, heart, blood vessels, and intestinal tract occurs, which leads to the loss of function of these organs and tissues.

Symptoms of vitamin D (cholecalciferol) poisoning are usually not seen until approximately 12 to 36 hours after consumption. Unfortunately, by the time the symptoms are noticed, the damage has already been done to the kidneys, and possibly the heart and liver as well. The most common symptoms of vitamin D (cholecalciferol) poisoning are:

• Bad breath
• Bloody feces
• Dehydration
• Diarrhea
• Drooling
• Excessive or decreased thirst
• Hemorrhage
• Increased or decreased urination
• Loss of appetite
• Seizures
• Sleepiness
• Stomach pain
• Tremors
• Vomiting (sometimes with blood)
• Weakness or lethargy
• Weight loss

 Types

• Acute cholecalciferol poisoning is caused by your dog eating a large amount of cholecalciferol from Vitamin D in a short period of time
• Chronic cholecalciferol poisoning occurs when your dog eats an unnecessary amount of cholecalciferol from Vitamin D over a long period of time, such as when an owner gives vitamin supplements that are not necessary

• Calcium supplements such as Caltrate or Calcitriol
• Concentrated vitamin D drops
• Any kind of multivitamins (including children’s)
• Omega fatty acid supplements
• Prescription vitamins

Your veterinarian will conduct a thorough physical examination, including urinalysis to check glucose and protein levels. Some other tests needed are a blood cell count (CBC) to check the levels of white blood cells, biochemistry profile to measure your dog’s phosphorous and calcium levels, and a parathyroid hormone concentration level test (PTH) to rule out underlying problems.

Radiographs (x-rays) are needed to check for mineralization in the organs and tissues. The veterinarian may also do an echocardiogram to measure your dog’s heartbeat because some dogs suffering from vitamin D poisoning have slowed heartbeats.

Because cholecalciferol poisoning can be life-threatening, immediate treatment is required, and your dog will most likely be admitted to the hospital for IV fluids to flush the toxins out of the body. They will give your dog a medication to make him vomit and several doses of activated charcoal a few hours apart to absorb what is left of the toxins. Gastrointestinal antacid will be used to lower your dog’s phosphorous levels and corticosteroids to reduce calcium levels. They will keep your dog at least 48 hours for observation.

Once your dog is stable, you can return home, but you must continue to monitor his urine output to be sure the kidneys are working correctly. You will have to go back every few days for about two weeks to check your dog’s calcium levels because any of your dog’s organs can fail from the calcification that occurred before treatment. In addition, it is important to return to your veterinarian if you notice any symptoms of organ shutdown. The symptoms of organ shutdown are varied, but the most common are vomiting, increased thirst, depression, lethargy, diarrhea, seizures, and coma. The prognosis for cholecalciferol poisoning from vitamin D depends on when treatment is given and how much vitamin D your dog consumed.