Vitamin D Toxicity in Dogs
Vitamin D is a fat-soluble vitamin (i.e., stored in the fatty tissues of the body and liver) that is vital in regulating the calcium and phosphorous balance in your dog's body. It also promotes the retention of calcium, thus aiding bone formation and nerve and muscle control. When ingested in exorbitant levels, however, vitamin D can cause serious health issues.
Chemicals used to kill rodents are the most common source of vitamin D poisoning in dogs, though excessive use of vitamin D in the diet or drugs containing high levels of vitamin D can also lead to toxicity. Dogs of all ages are susceptible, but young dogs and puppies are at higher risk.
Symptoms and Types
Symptoms usually develop within 12-36 hours after ingestion of rodent killing agents. However, the time in which the symptoms become readily visible may vary depending on the source of vitamin D toxicity. Such symptoms may include:
- Loss of appetite
- Increased thirst (polydipsia)
- Increased urination (polyuria)
- Dark tarry feces containing blood
- Blood in vomit
- Loss of weight
- Muscle tremors
- Abdominal pain
- Excessive drooling
- Accidental ingestion of rodent-killing chemicals
- Excessive use of vitamin D dietary supplements
Your veterinarian will take detailed history about your dog's diet and any supplements it may be taking. He or she will also ask if your dog has access to rodent-killing chemicals at home or in your yard. A complete physical examination will then be conducted, including routine laboratory tests such as a complete blood count, biochemistry profile, electrolytes, and urinalysis.
If your dog is suffering from vitamin D toxicity, the biochemistry profile will indicate abnormally high levels of calcium and phosphorous in the blood. It may also indicate abnormally low levels of potassium in the blood along with an accumulation of nitrogenous waste products. In some dogs, the biochemistry profile may even indicate an abnormally high level of liver enzymes and low levels of protein (called albumin) in the blood. The urinalysis, meanwhile, will indicate abnormally high levels of proteins and glucose in the urine.
Some patients with vitamin D toxicity also show various blood clotting derangements, like bleeding from various body sites due to excessive loss of platelets (cells responsible for the clotting of blood).
More specific testing will include measuring the levels of vitamin D in the blood and an ECG (echocardiogram) to evaluate your dog's heart. Various abnormalities, including abnormally slow heartbeat, may be found in dogs suffering from vitamin D toxicity.