Fluoride Poisoning in Dogs

Fluoride is a naturally occurring chemical found in untreated water sources and a synthetic version of it is used as an additive in water supplies in many towns and cities. Although it is an effective way to prevent cavities, in large doses it can become toxic. Severe poisoning can occur if your dog eats something with a very large amount of fluoride such as toothpaste. This generally begins with the inflammation of the stomach and intestines followed by an increased heart rate with abnormalities. The fluoride is absorbed into the system within 90 minutes and will generally result in collapse and death within a few hours if it is untreated. Chronic overexposure to fluoride can result in weakened bones or abnormal bone growths as well as chronic gastric disorders.

Fluoride is a naturally occurring chemical that canines can be particularly sensitive to. Fluoride toxicity due to overexposure is extremely serious and it can be acute or chronic.

Some of the symptoms of fluoride toxicity such as lameness or muscle wasting are only likely to be seen when the exposure to higher than normal levels of fluoride has been chronic.

• Depression 
• Diarrhea 
• Excessive drooling
• Gastroenteritis
• Labored breathing
• Lameness
• Lethargy
• Loss of appetite
• Muscle wasting 
• Muscle weakness 
• Rapid heart rate
• Restlessness
• Seizures
• Stiffness
• Sudden death
• Sweating
• Vomiting
• Weight loss

Types

Calcium fluoride

• This is the variety of fluoride that is found most often in nature
• A fluoride molecule bonds with a calcium molecule to create calcium fluoride
• Although calcium fluoride is more easily tolerated by the body than synthetic fluorides, it can be just as lethal at high doses

Sodium fluoride

• This is the first synthetic fluoride that was introduced to the water supply
• It is a white, odorless additive which has to be dissolved before adding it to the water supply

Sodium fluorosilicate

• A dry additive which has to be dissolved before adding it to the water supply. This is fluorosilicate acid bound with sodium giving it a powdered or crystallized structure making it much easier to ship

Fluorosilicic acid

• An inexpensive by-product of phosphate fertilizer manufacture in liquid form, also known as hydrofluorosilicate, HFS, or FSA. It is more commonly used, but can be quite expensive to ship

Significant sources of fluoride for your canine:

Dog food

• Some dog foods have a high amount of fluoride in their make up
• Foods with large amounts of bone meal are more likely to have high fluoride levels due to the tendency for fluoride to accumulate in the bones

Fluoridated dental products

• Fluoride is added into most toothpastes and gel treatments for humans
• Due to the canine sensitivity to fluoride, it is rarely added to toothpastes designed for dogs
• Human dental products may also contain xylitol, which is extremely toxic to canines

People food

• Some food that people eat have higher concentrations of fluoride than others
• Foods with notable amounts of fluoride can include cucumbers, pickles, spinach and canned tomato products 

Water supply

• Supplemental fluoride is added to the water supply in most areas in the US, and some water supplies have naturally high fluoride levels

If it is a reaction to a single large dose and you have any of the remaining product or package, you will want to bring that with you to the clinic as well. Your veterinarian will need to get a full history from you, taking special note of the diet and any opportunistic eating as well as a progression of symptoms. That information, combined with a physical examination will help reach a conclusive diagnosis. The physical examination will check for inflammation, and will take particular note of any heart rhythm abnormalities. There are several disorders which may mimic chronic fluoride overexposure. A complete blood count, biochemistry profile, and urinalysis are likely to be done at this time as well to rule out other disorders with the same symptoms, as well as detect any toxins in the system. Fluoride usually does not remain in the body longer than 24 hours so this method of detection may provide a false negative.

An acute case of fluoride poisoning can kill within just a few hours time so time is of the essence if the disorder is to be corrected. If you know what your pet ingested contact the veterinarian immediately. If ingested recently enough, your veterinarian may opt to have you induce your dog to vomit to avoid the absorption of any toxins before travelling to the office. Patients that develop acute fluoride poisoning can be given calcium gluconate intravenously and magnesium hydroxide or milk by mouth to minimize absorption, although this is not always successful and the patient may ultimately succumb to the imbalance.  Chronic fluoride poisoning also has a poor prognosis, and once the outward signs have developed reversal is unlikely. Your veterinarian may be able to recommend a low fluoride dog food and specific supplements may be added to your pet’s diet to reduce the absorption of the fluoride. These measures will not reverse or stop the progression of the disorder but it may slow the development of additional symptoms for a time.

Keeping the recovering patient in a quiet and calm environment and making sure that he or she completes the full measure of any prescribed medications will help encourage recovery. Medications to guard against secondary infection or to protect the gastrointestinal system may be recommended. In order to reduce the symptoms and slow the progression of the disorder, the patient may need to be placed on a diet restricted to low-fat, high-fiber foods until any inflammation has gone down. In the case of chronic fluoride poisoning it is essential to track down and eliminate the source of the overabundance of fluoride in the diet or environment of the animal.