Chocolate Toxicity

What is chocolate toxicity?

Chocolate toxicity (poisoning) is caused by excessive intake of the methylxanthine alkaloids in chocolate, coffee, tea and caffeinated sodas. The active ingredient in chocolate is theobromine. The poisoning affects many organ systems and animals of all ages are susceptible.

Poisoning is common in dogs because of their habit of rapid consumption, particularly puppies and young dogs as they may be more likely to ingest large amounts of unusual foods. Although dogs are the most susceptible, the toxin has been known to affect or kill cats, birds, rodents and reptiles as well.

Toxic dosages for dogs :

Below is a list of potentially dangerous doses of chocolate. Please note that these are approximate amounts only. Every animal has varying levels of sensitivity to theobromine. Caffeine will enhance the toxicity of theobromine. Some brands of chocolate have more caffeine than others (example: Nestle's milk chocolate has 19 mg caffeine per oz versus Hershey's milk chocolate has 8 mg caffeine per oz).

 
Dog's weight (lbs) Amount of milk chocolate (oz) Amount of chocolate chips (oz) Amount of unsweetened chocolate (oz) Approximate amount of theobromine (mg)
5 4 1.5 0.5 200
10 8 3 1.5 400
20 16 6.5 2.5 900
30 28 9.5 3.2 1300
40 40 13.3 4.5 1800
50 48 16.6 5.5 2250
60 60 20 6.7 2700
75 76 25.2 8.5 3400
 

Clinical signs

The clinical signs include vomiting, diarrhea, hyperactivity, restlessness, excessive urination, muscle tremors, tachycardia, bradycardia, arrhythmias, hyperthermia (high temperature), seizures, coma and death. Vomiting and diarrhea can occur 2 to 4 hours after intake. Advanced signs (seizures, heart failure, coma and death) can occur 12 to 36 hours after intake.

Diagnosis

The patient may have a history of exposure to a methylxanthine. The clinical signs are important, but chocolate toxicity can look similar to many poisonings such as that caused by strychnine, amphetamines, pesticides and some rodenticides. The stomach contents, serum, or urine can be analyzed for the presence of methylxanthine alkaloids (caffeine, theophylline, and theobromine).

Treatment  

If your pet has just ingested chocolate, emetics (medications that induce vomiting) can be used but consult with a veterinarian first.  Emetics are contraindicated if the pet is twitchy, unaware of his/her surroundings or seizuring. 

  • Take your pet to an emergency facility immediately.
  • Supportive treatment: There is no antidote for chocolate poisoning. The patient needs to be hospitalized for supportive treatment and observation.
  • Activated charcoal may be administered every 3-4 hours to reduce the serum half–life of methylxanthines.
  • Intravenous fluid therapy may be used to help flush out the toxins.
  • In some cases oxygen therapy may be needed.
  • Sedation is necessary for some patients that are very hyperactive.
  • The patient’s cardiovascular system function may require monitoring with ECG, blood pressure, oxygen saturation and/or blood gases.
  • Medication may be required to treat a slow, very fast, or irregular heart beat.
  • Insulin administration may be beneficial to treat caffeine poisoning, as insulin has been shown to be antagonistic to caffeine.

Potential complications  

If a 50 mg/kg dose of theobromine is ingested, cardiotoxicity (heart complications) can be seen. At 60 mg/kg, seizures are possible. Any dose over 40 mg/kg should be considered life-threatening. 100mg/kg is the LD50 meaning that at this dose half of the animals will die. Animals can die from exposures well below the LD50. Pregnant or nursing animals are at risk for teratogenesis of newborns or stimulation of nursing neonates.

Aftercare (home care)  

It is important to remember to keep chocolates, chocolate cakes and chocolate-coated goodies safely away from your pets.

Prognosis

Patients usually recover with aggressive supportive therapy under the direction of a veterinarian. If the ingestion and the treatment are performed in the first 4 hours, the prognosis is good. Heart failure, weakness, seizures, coma and death can occur 12 to 36 hours after ingestion and the prognosis may be guarded.

Published on October 27, 2012.