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Sileo (dexmedetomidine otomucosal gel)

Efficacy & Safety



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The efficacy and safety of SILEO® (dexmedetomidine oromucosal gel) have been proven in several placebo-controlled studies.


New Year’s Eve Study

Efficacy was evaluated in two studies conducted on New Year’s Eve in Europe* to explore treatment effect under the actual conditions of use with an authentic noise stimulus: fireworks. These studies (randomized, multi-center, double-blind, placebo-controlled) evaluated the effect of SILEO in client-owned dogs with noise aversion. The first study found that 125 mcg/m2 was the lowest effective dose. The second study confirmed safety and efficacy at 125 mcg/m2. Pet owners were allowed to administer up to five doses, with a minimum of 2 hours between doses, on an as needed basis.

  • SILEO had excellent or good treatment effect in 75% of dogs
  • Placebo had excellent or good treatment effect in 33% of dogs
  • The difference between the two groups was statistically significant at p<0.0001, in favor of SILEO

*Finland and Germany were selected because New Year’s Eve fireworks last throughout the night.

Bar graph comparing the efficacy of Sileo (N=71) to Placebo (N=73)

Assessment of Signs and Extent of Fear and Anxiety

Pet owners were also asked to assess which signs of fear and anxiety their dogs exhibited, as well as the severity of those signs before and after each treatment.

  • Mean sum of behavior scores over the treatment period was significantly different in favor of SILEO (p=0.0069)
  • Dogs treated with SILEO displayed less panting, trembling and trying to hide than those treated with control

Line graph comparing behavior scores for Sileo versus Placebo from Pre-Dose 1 to Pre-Dose 4

The Calming Effect of SILEO is Not Due to Sedation

Pet owners were also asked to assess the level of alertness in their dogs throughout the evening.

  • The data from time points when dogs presented signs of potential sedation based on alertness assessment 1 hour after dosing were excluded from the efficacy analysis
  • Removal of these dogs from the efficacy data means that the calming effect of SILEO was independent of sedation
  • No signs of excessive sedation were observed in the SILEO group


  • SILEO treatment effects were measurable, relevant and statistically significant (p<0.0001)
  • 75% of SILEO-treated dogs scored an “excellent effect” or “good effect”
  • 48% percent of placebo-treated dogs scored “no effect” or “worse effect”
  • Severity and frequency of signs was significantly lower in SILEO-treated dogs (p=0.0069)
  • SILEO-treated dogs displayed less trembling, hiding and panting
  • Calming effect of SILEO was independent of sedation


Pivotal Field Study

The adverse reaction rate for this study was low, as shown below.

Adverse Reactions – Number (%) of dogs

Adverse Reactions table comparing the Control N=92 and Dexmedetomidine N=89

Additionally, transient pale mucous membranes were noted in SILEO-treated dogs. Gel application did not result in mucosal irritation.


The administration of 125 mcg/m2 of SILEO, as needed, up to five times with a minimum interval of 2 hours between doses is safe and effective for the treatment of noise aversion in dogs.


Sign in to Order** If you are a customer in Hawaii, please contact your local Zoetis Sales Representative or Hawaii Mega-Cor to place your order.

Important Safety Information: Do not use SILEO in dogs with severe cardiovascular disease, respiratory, liver or kidney diseases, or in conditions of shock, severe debilitation, or stress due to extreme heat, cold or fatigue or in dogs hypersensitive to dexmedetomidine or to any of the excipients. SILEO should not be administered in the presence of preexisting hypotension, hypoxia, or bradycardia. Do not use in dogs sedated from previous dosing. SILEO has not been evaluated in dogs younger than 16 weeks of age or in dogs with dental or gingival disease that could have an effect on the absorption of SILEO. SILEO has not been evaluated for use in breeding, pregnant, or lactating dogs or for aversion behaviors to thunderstorms. Transient pale mucous membranes at the site of application may occur with SILEO use. Other uncommon adverse reactions included emesis, drowsiness or sedation. Handlers should avoid direct exposure of SILEO to their skin, eyes or mouth. Failure to lock the ring-stop on the syringe before dosing SILEO could potentially lead to an accidental overdose. Always review INSTRUCTIONS FOR USE before dispensing and dosing. See full Prescribing Information.



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