Below is the ASPCA Animal Poison Control Article: 

Cocoa Bean Mulch As A Cause Of Methylxanthine Toxicosis In Dogs
by S. Hansen, H. Trammell, E. Dunayer, S. Gwaltney, D. Farbman, and S. Khan

Background: Cocoa bean shells, a by-product of chocolate production, are sold as mulch for landscaping. Homeowners find cocoa mulch desirable because it degrades into an organic fertilizer and provides an attractive color and odor. Unprocessed beans, derived from the Theobroma cacao plant, contain 1-4% theobromine/0.07-0.36% caffeine whereas, cocoa bean mulch contains 0.19%-2.98% theobromine. Some dogs find the mulch attractive and eat small to large quantities.

- Cocoa bean shell products are increasingly used as mulch

- Natural cacao beans are derived from Theobroma cacao

- Unprocessed beans contain 1-4% theobromine and 0.07-0.36% caffeine

- Cocoa bean shell mulch may contain up to 0.19%-2.98% theobromine Cocoa bean shells are a by-product of chocolate production

- Cocoa bean shell mulch products have an attractive odor and smell

- Some dogs will eagerly eat large amounts of cocoa bean shell mulch

 

Treatment of Clinical Signs Resulting from Methylxantine Toxicosis in Dogs Clinical Sign Drug Dose Seizure diazepam 0.5-2 mg/kg IV phenobarbital 2-6 mg/kg IV slowly       Tremor diazepam 0.5-2 mg/kg IV methocarbamol 50-220 mg/kg IV slowly Bradycardia atropine 0.01-0.02 mg/kg IV Tachyarrhythmia propranolol 0.02 - 0.06 mg/kg IV slowly metoprolol 0.04-0.06 mg/kg IV slowly lidocaine 1-2 mg/kg IV slowly, then infuse at 30-50 mcg/kg/min

Conclusion: Dogs consuming cocoa bean mulch may develop methylxanthine toxicosis. Retrospective case data suggests clinical signs following ingestion include vomiting and muscle tremors. Although oral doses could not be quantitatively determined, clinical severity increased with increasing qualitative dose descriptions. Therefore, treatment should be directed at controlling clinical signs until recovery and preventing further exposure. Pet owners should avoid use of cocoa bean mulch in landscaping around dogs with indiscriminate eating habits.

- Low doses of methylxanthines in dogs cause gastrointestinal upset

- High doses cause tachycardia, muscle tremors, seizures and even death

- Drolet documented the death of a dog after eating a large amount of cocoa bean shell mulch containing 0.46% theobromine

- Cases we managed involved dogs which developed vomiting, tremors, tachycardia, hyperactivity, or diarrhea with full recovery

- Clinical severity appears to correlate with increasing qualitative dose descriptions

- Treatment of affected dogs includes multiple dose activated charcoal (2g/kg PO) and tremor control with cardiac monitoring

- Urinary bladder catheterization may reduce reabsorption of methylxanthines

- Other potential exposures include pesticides and mycotoxin-producing mold

- Dogs may experience clinical effects from large ingestions of cocoa bean shell mulch but life-threatening signs were not reported

- We recommend avoiding use of cocoa bean shell mulch in landscaping around unsupervised dogs