Mercury Poisoning in Dogs

Mercury occurs naturally in several forms. Too much mercury in your dog’s body can damage the cardiovascular system, nervous system, kidneys, and digestive tract. Continued exposure can also injure the inner surfaces of the digestive tract and abdominal cavity, causing lesions and inflammation. There have also been reports of lesions in the central nervous system (spinal cord and brain), kidneys, and renal glands. Many causes of mercury poisoning in dogs is caused by eating button batteries, glass thermometers, light bulbs, and fish. However, there are cases of mercury poisoning from mercury found in the soil, groundwater, or even vapors from burning oil or gas. The lights in tennis shoes that light up when you walk are also toxic, and should be kept away from your dog. If you believe your dog has been exposed to mercury in any form, you should visit your veterinarian right away, even if there are no evident symptoms.

Mercury poisoning used to be a common condition in people and their pets, but since the discovery of mercury replacement material for professional use, it has become much less common. However, there are still many things containing mercury that can affect your dog, such as fish, latex paint, fluorescent light bulbs, and button batteries. As a matter of fact, mercury is still found in high levels in many types of fish used in commercial canned pet food. While an occasional can of tuna or salmon may not be harmful, feeding this to your dog on a daily basis can be harmful within a few months because mercury builds up over time since it does not get expelled from the body readily.

The symptoms of mercury poisoning are gradual, so they sometimes go unnoticed until the levels of mercury are high enough to cause severe symptoms. The nervous system is usually the first to be affected by mercury poisoning. This is because the brain holds mercury longer than any other part of the body, so the toxin builds up to cause damage to the central nervous system. Your dog may not start to show any symptoms at all until one or two months after exposure, making the diagnosis extremely difficult. Although most often the signs are gradual, dogs exposed to a high level of mercury can have immediate and obvious symptoms, such as:

• Abdominal pain
• Abnormal behavior and chewing
• Anxiety
• Blindness
• Coma
• Convulsion
• Damage to the kidneys (inability to urinate, abdominal swelling)
• Death
• Lack of coordination
• Loss of feeling in paws
• Nervousness
• Tremors
• Vomiting blood
• Watery and bloody diarrhea

 Types

• Acute mercury poisoning is exposure to a high level of mercury that causes symptoms right away
• Chronic mercury poisoning happens gradually from exposure to smaller amounts of mercury on a daily basis

• Eating contaminated fish or fish products
• Exposure to contaminated soil
• Breathing toxic fumes from burning oil or trash

Eating other items that contain mercury, such as

• Latex paint
• Fluorescent light bulbs
• Button batteries
• Glass thermometers
• Children’s light-up tennis shoes

Because your dog may not start to show any symptoms at all until one or two months after exposure, making the diagnosis extremely difficult. However, if you suspect that your dog has been exposed to mercury or some other poison, be sure to let the veterinarian know before they do any tests. Even if you are bringing your dog to the veterinarian because of symptoms not mentioned in this article, tell the veterinarian what you believe your dog was exposed to, how much, and when it happened. He will do a complete physical examination, check vitals (body temperature, breathing rate, blood pressure, and pulse) reflexes, height and weight. Next, they will do some tests, such as urinalysis, fecal flotation, complete blood count (CBC), blood chemical analysis, blood gases, and fecal cultures. A kidney biopsy will be done by using a fine needle biopsy to get a small sample of tissue to examine microscopically. Radiographs (x-rays), CT scans, MRI, and ultrasound of the abdomen and brain are usually done as well to see how far the damage has gone. If the veterinarian suspects damage to the central nervous system, an electroencephalogram (EEG) will be done to record your dog’s brain activity.

Your dog will be hospitalized and given IV fluids, oxygen therapy, antibiotic, and anti-inflammatory medications. The veterinarian will usually try an activated charcoal lavage and a chelation medication, such as penicillamine or dimercaprol, to bind to the mercury so it can be eliminated through the kidneys in the urine.

Unfortunately, the damage done by the mercury is not reversible, so if your dog has severe central nervous system, cardiovascular, or renal damage, it is permanent. Many dog owners choose euthanasia if their quality of life is expected to be low. To prevent this from happening again, keep items with mercury out of the reach of your dogs.