Manish Kumar Verma*
Introduction:
There are various food items that are suitable for being consumed by humans because these can be easily digested, metabolized and excreted but on the other side can be hazardous to dogs. One of these food items is chocolate. Chocolate poisoning is common in dogs but other species are also susceptible. Chocolate is produced from the beans of Theobroma cacao that are manufactured into cocoa solids and cocoa butter. Chocolate consists of two main components Theobromine and caffeine. Out of which Theobromine, a Methylxanthineis more potent toxin. This mainly causes central nervous system excitation, cardiac stimulation and respiratory system hyperactivation. Primary signs of poisoning in dogs include vomiting, haematemesis, and polydipsia. Polyuria, hyperirritability, tachycardia, excessive panting, ataxia, and muscle twitching are also observed. Sometime effects may progress to cardiac arrhythmias, seizures, and death of animal occurs. The poisoning occurs due to lack of knowledge to people concerning the serious health threat to dogs. It is caused by indiscriminate eating habits and easily available sources of chocolate.
Etiology:
- Accidental ingestion of chocolate
- Transplacental transmission of Theobromine in developing foetus
- Transmammary transmission of Theobromine in suckling neonates
Mechanism of Toxicity:
Theobromine and Caffeine is absorbed from gastrointestinal tract and distributed throughout the body. They are metabolize in liver and excreted in the urine. Half-life of Theobromine and Caffeine is 18 hours and 5 hours respectively in dogs. LD50 of both theobromine and caffeine is 100-200 mg/kg.Theobromine and Caffeineshow competitive inhibition of Adenosine receptors present in cell membrane. Also Theobromine inhibit cellular uptake of Calcium which causes increase in intracellular Calcium level hence there is increased contractility of skeletal and smooth muscles. Methylxanthine also competes for Benzodiazapene receptors within the central nervous system and inhibit Phosphodiesterase enzyme, resulting in increased cyclic AMP levels. Methylxanthine may also increase epinephrine and norepinephrine level.
Toxic signs:
Common clinical signs likevomiting, diarrhea, panting, restlessness, increased thirst and increased heart rate are observed under low dose toxication. Clinical signs are changed to cardiotoxic as the dose progresses and at very high doses nervous signs like seizures, muscle tremors and heart failure are observed. Death may occur due to cardiac arrythemia or asphyxia. Toxic Symptoms and signs will starts appear within two hours of ingestion, but it metabolised slowly, it can take as long as 24 hours. In severe cases, symptoms can last up to 72 hours. Early treatment will help your dog recover quicker.
Diagnosis:
- History of accidental chocolate ingestion.
- Clinical signs along with presence of chocolate odour from vomitus, saliva and feces.
- ECG showing abnormalities in rhythm or conduction of heart
Treatment:
- There is no specific antidote for theobromine. Every dog is different and the exact treatment protocol has to be adjusted according to the quantity of chocolate thought to have been consumed and the symptoms that the dog is displaying.
- If the dog has consumed the chocolate recently and not vomited yet, then vomition is induced by administration of apomorphine0.04 – 0.1 mg/kg body weight SC.
- Diazepam 0.5-2mg/kg slow IV or used for seizures and muscle tremors; phenobarbital @2-3 mg/kg b. wt. orally BIDmay be require for severe seizures.
- The circulation needs to be supported by fluid therapy i.e. Dextrose normal saline 20ml/kg body weight IV.
- Activated charcoal 1-3 g/kg body weight orally, repeated at every 8 hours. This is necessary to prevent Theobromine from getting absorbed again for enterohepatic circulation, after getting metabolized by liver.
- Other treatment includes maintaining acid base and electrolyte balance.
Differential Diagnosis:
The chocolate poisoning should be differentially diagnosed with Amphetamine and Cocaine toxicosis and ingestion of Antihistaminics.
Outlook:
It depends upon how much chocolate or cocoa powder the dog has eaten and how long before the consumption has occurred. Death may occur if treatment is delayed until severe, persistent vomition has developed. If seizures have developed, then prognosis is guarded.If the treatment is early except for dogs that have consumed very large quantities of chocolate, the outlook is generally quite good.
* Author is currently pursuing Ph. D in Veterinary Pharmacology and Toxicology from the college of Veterinary and Animal Sciences, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttrakhand. He served as a guest faculty (2018 to 2019) in the department of Veterinary Pharmacology, N. D. University of Agriculture and Technology, Ayodhya, Uttarpradesh. He has, over the years, investigated the immunomodulatory and antioxidant property of phytochemicals. He is currently working on the evaluation of Fipronil on xenobiotic metabolism.
