Botulinum toxin decreases salivation from canine submandibular glands

The objective of this study was to determine whether botulinum toxin types A and D reduced the production of saliva from the submandibular glands of 18 dogs. The left submandibular glands of 8 dogs were injected with increasing doses of botulinum type A toxin (range 10 to 70 units), and the left glands of 10 dogs were injected with botulinum type D toxin (50 or 100 units). The right gland of each dog was injected with equivalent volumes of saline solution to serve as control. Six days after the injection, the lingual nerve was electrically stimulated for 10 minutes (3 mAmp, 20 Hz). The resulting volume of saliva was collected and weighed. Overall, the glands injected with types A or D toxin produced significantly less saliva than comparable glands injected with saline solution. Six of 8 dogs injected with type A toxin showed a significant decrease in saliva production (range 10.1% to 19.2%, one-sided p value = 0.0375) when compared with the controls. Nine of 10 dogs injected with type D toxin demonstrated a highly significant reduction in saliva production (total average decrease = 60%, two-sided pvalue = 0.001) when compared with the controls. We concluded that intraglandular injections of botulinum toxin types A and D significantly reduced the production of saliva from canine submandibular glands. The potential applications of intraglandular injections of botulinum toxin are discussed.