Management of Chocolate Intoxication
ACVIM 2008
Kimberly Baldwin, LVT, VTS (ECC)
Manager of Nursing Services
Ithaca, NY, USA

Introduction

Chocolate intoxication can be seen in all breeds but it is predominant in the canine species. Animals may have easy access to this toxin and the pleasant odor and palatability make it easy to digest. This lecture will review the mechanisms of action for methylxanthine, methylxanthine content in products, calculating toxic dose, treatment, and after care of the patient that has digested chocolate.

Mechanism of Action

Methylxanthines are the bioactive agents in chocolate and related products. Theobromine is the most active methylxanthine found in the cocoa bean. Caffeine is also present in most cocoa. Methylxanthines are eliminated primarily through liver metabolism and are quickly absorbed in the GI system. The fat content in the chocolate may have a tendency to slow down the process. Increased GI secretion causes mucosal irritation. Methylxanthines inhibits phosphodiesterase causing accumulation of intracellular cyclic adenosine monophosphate(c-AMP). This, in turn, produces and increased amount of circulating catecholamines (epinephrine, and norepinephrine.). The methylxanthines are competitive antagonists of cellular adenosine receptors which cause an interference with the uptake and storage of calcium in striated muscle, causing muscle contraction.

Clinical Signs

Clinical signs for theobromine and caffeine are similar. Chocolate intoxication primarily affects the neurologic and cardiac system. Clinical signs usually occur within 1-4hrs post ingestion. The most common clinical signs are hyperexcitability, restlessness, tremors, tachycardia, tachypnea, seizures, vomiting, and premature ventricular beats. Hypertension and hyperthermia may also occur. Hypotension, bradycardia, and coma are seen with severe or fatal doses. Pancreatitis can be a rare secondary occurrence due to the high fat content of the chocolate. Lab data is usually limiting. Occasional hypoglycemia secondary to muscle activity, and low urine-specific gravity due to the diuretic effect of the drug may be seen. Caffeine and Theobromine can be detected in serum, stomach content or urine but testing does not routinely occur. Ruling out other toxins such as amphetamine, antihistamine, decongestant or cocaine should occur if chocolate ingestion is not confirmed by owner or physical exam.

Methylxanthine containing products.

Product

Theobromine
(mg/oz)

Caffeine
(mg/oz)

White chocolate

Trace amount

Trace amount

Milk chocolate

58

6

Dark chocolate

130

20

Semisweet chocolate.

138

22

Baking chocolate

393

47

Dry Cocoa powder

737

67

Cocoa beans

600

NA

Toxic Doses of Methylxanthine

Toxic dose of theobromine may vary. The average toxic dose for the dog is 100mg/kg. The toxic dose of caffeine is approximately 140mg/kg. All patients may react differently at varying levels of ingestion. Early detection and treatment of clinical signs is critical to the success in the treatment of methylxanthine toxicity.

The total amount of methylxanthine is calculated by determining the amount of theobromine and caffeine in a product. For mixed products (nuts, jelly) presume 100% is chocolate. When actual amounts are not known, estimate total content that could have been ingested. The total amount of methylxanthine ingested in mg should be divided by the animal body weight in kgs to determine the total mg/kg dose ingested.

Developing a Treatment Plan

There is no specific antidote for methylxanthine. Ensure a patent airway and supply oxygenation if the patient arrives in a comatose stupor. Standard treatments of oral ingestion of toxins apply. Induce vomiting, +/- gastric lavage, and activated charcoal with cathartic. An IV catheter should be established and a balanced electrolyte crystalloid fluid should be maintained to provide perfusion, hydration and diuresis. An ECG should be monitored for supraventricular arrhythmias and ventricular tachycardia. Encourage frequent urination or catheterize the bladder. Methylxanthines may be reabsorbed through the bladder wall, prolonging the symptoms. Gastric protectants may decrease GI irritation.

Induction of Emesis

Emesis should be considered if the toxin has been ingested within the past 1-4 hours. In the cat, xylazine can be given IM or SQ or 3% hydrogen peroxide ( 1-2ml/kg). In the dog apomorphine (.03mg/kg) or topical conjunctival dose (.3mg/kg) Make sure to rinse the conjunctival sac out with saline after the vomiting occurs.

Gastric Lavage

When a toxic dose of methylxanthine has been ingested or when emesis was not effective gastric lavage may be indicated.

1.  The animal is placed under light anesthesia to allow endotracheal intubation with cuff inflation. Cuff inflation will protect the airway from aspiration of GI contents.

2.  Place the animal in lateral recumbancy.

3.  Pre-measure a large bore stomach tube from the tip of the nose to the last rib. Mark the tube.

4.  The tube should be lubricated with K-Y jelly and then passed gently down the esophagus toward into the stomach.

5.  Infuse warm water (10-15ml/kg body weight) through the tube to moderately distend the stomach. The exterior end of the tube is then rapidly lowered below the level of the stomach and placed in a bucket to allow drainage of the stomach content.

6.  Lavage should be repeated with the animal in a different position to ensure complete evacuation of toxins.

7.  Mixing the lavage fluid with activated charcoal may enhance the effect of the gastric lavage.

8.  Continue the lavage until stomach content is clear.

9.  Kink the end of the stomach tube before removal.

10.  The oropharynx and mouth should be suctioned if any access fluid is noted in this area.

11.  Close monitoring of anesthesia should occur leaving the tube cuffed until the patients swallow reflex is present.

Activated Charcoal

Ideally, activated charcoal administration can initially occur at the time of gastric lavage. A repeat dose 4-6 hrs post administration may be needed to eliminate the recirculation of theobromine and will enhance elimination.

Standard dose of activated charcoal with cathartic is 1-4g/kg of body weight mixed in 50-150 mls of water. Activated charcoal can be given orally or via a stomach tube. The cathartic within the activated charcoal hastens the elimination of the ingested toxins. Activated charcoal administration can be very messy. The appropriate precautions should be used to provide protective clothing when administering. There is minimal side effects to administration of activated charcoal, constipation may occur. It is important to prepare the owners that their animal will have black stools for a few days.

ECG Monitoring

Monitoring of the cardiovascular system should occur. If the patient is tachycardic B blockers may be needed. Treatment with esmolol, propranolol or metoprolol has been suggested. Metoprolol is preferred over propranolol because propranolol may reduce methylxanthine clearance. If the patient has PVC's, administration of lidocaine may be suggested. Blood pressure should also be routinely evaluated

Seizure Control

Seizure control should be administered to effect. Diazepam (.5-1mg/kg IV) Sometimes seizures are not controlled by diazepam alone. Phenobarbital or propofol may be required

After Care

Once the animal is stabilized they can be removed from IV fluids and offered water and a bland diet. Observation usually occurs for 24-48hrs post treatment depending on clinical signs.

Early and aggressive intervention increases the opportunity for a favorable recovery.

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Kimberly Baldwin, LVT, VTS (ECC)
Cornell University
Ithaca, NY


MAIN : Specialist : Chocolate Toxicity
Powered By VIN
SAID=27