Suspected poisoning is a common reason for presentation in veterinary practice, particularly during the Christmas and Easter periods. To date, only a few individual case reports describing chocolate intoxication in dogs have been published, but a new study published in the Journal of Small Animal Practice (JSAP), described the clinical features and outcome of dogs after chocolate ingestion.
In the study, “Chocolate ingestion in 156 dogs”, the medical records of dogs presenting to a single institution over the course of four years following chocolate ingestion were retrospectively evaluated. Information relating to the signalment, history, amount and type of chocolate ingested, presenting clinical signs, physical examination findings, results of laboratory examinations, treatment and outcomes were collected. Dogs were only included if chocolate ingestion was directly observed by the owner.
The concentration of theobromine and caffeine were calculated in relation to bodyweight for each case. If the chocolate consumed by the dog was composed of different types of chocolate and the proportions were unknown, the chocolate with the highest methylxanthine content was used. This may have resulted in an overestimation of methylxanthine content in some cases. Methylxanthines can be detected in blood or urine which may be useful in cases where the cause of intoxication is unclear or for forensic purposes, but this was deemed unnecessary in this study as all dogs were observed ingesting chocolate.
Over the study period, 156 dogs were presented to the clinic because of chocolate ingestion. Most dogs were presented during December (20.2%), followed by April (11%) and March (10%). Of those dogs, 112 presented without clinical signs and 44 presented with clinical signs of chocolate intoxication.
Of those dogs that presented without clinical signs, most had ingested milk chocolate (54%), whereas most of those that presented with signs of chocolate intoxication had consumed dark or bitter chocolate (64%). This finding aligns with the calculated maximum methylxanthine concentrations in both groups of dogs; the median calculated maximum theobromine dose was 22.4 mg/kg and the median calculated maximum caffeine concentration was 10.2 mg/kg in dogs presenting without clinical signs. This compares to a median maximum theobromine concentration of 70.8mg/kg and median maximum caffeine concentration of 21.7mg/kg in the dogs presenting with signs of chocolate intoxication.
In all dogs without clinical signs of chocolate intoxication, physical examinations findings were normal, and laboratory examinations, where undertaken, also showed no abnormalities. The most common presenting signs for those dogs with clinical signs of chocolate intoxication included restlessness (75%), tremor (50%) and vomiting (48%). Clinical examinations of dogs presenting with clinical signs of chocolate intoxication revealed panting or tachypnoea (32%), hyperthermia (23%) and moderately moist to dry mucous membranes (16%). Abnormal clinical pathological findings included hyperlactataemia (92%), hypokalaemia (47%), mild hyperglycaemia (47%) and mild alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation (41%).
The prognosis of methylxanthine intoxication caused by chocolate ingestion was good in this study; only one dog died, four hours after receiving symptomatic treatment. The patient presented with a pronounced sinus tachycardia, mild hyperthermia, vomiting and seizure after ingesting 100g of dark chocolate 12 hours previously (theobromine concentration 64mg/kg, caffeine 19.7 mg/kg). Of those dogs that presented without clinical signs of chocolate intoxication, 86% received apomorphine, 2% received a gastric lavage under general anaesthesia, 15% were treated with fluid therapy and 43% received activated charcoal. In comparison, dogs that presented with clinical signs of chocolate intoxication, all dogs were treated with fluid therapy and antiemetics, 48% received apomorphine, 23% were treated with esmolol, 14% with forced diuresis and 5% with sedatives.
The findings of this study suggest that the type and amount of chocolate ingested, and the time of ingestion, are important factors when considering appropriate therapy for patients.
Weingart C, Hartmann A and Kohn B (2021) Chocolate ingestion in 156 dogs. Journal of Small Animal Practice, 62 (11). Available at: https://onlinelibrary.wiley.com/doi/10.1111/jsap.13329