Effect of doxycycline on contralateral canine cranial cruciate ligament rupture. A prospective randomized clinical trial in 69 dogs

Vet Comp Orthop Traumatol. 2015;28(6):371-8. doi: 10.3415/VCOT-15-02-0034. Epub 2015 Oct 1.


Objective: To evaluate whether doxycycline administered to dogs with unilateral cranial cruciate ligament rupture (Uni-CCLR) would decrease the risk of contralateral-CCLR (Co-CCLR). To evaluate predictors for Co-CCLR survival. To evaluate if a predisposition of Labrador Retrievers to Co-CCLR exists when compared to other breeds.

Methods: In this prospective randomized controlled clinical trial, 69 client-owned dogs with Uni-CCLR were randomly assigned to a doxycycline (group-D: 7.5 mg/kg PO BID x 6 weeks) or non-doxycycline (group-ND: negative control). Medical and imaging data, time from Uni- to Co-CCLR and to follow-up were recorded. Statistics included chi-squared test, logistic regression, Kaplan-Meier survival analysis, log rank test, survival curves, and frailty model (p <0.05).

Results: This study included 32 dogs in group-D, and 37 dogs in group-ND. Median follow-up was 54.5 and 61 months, respectively. Contralateral CCLR occurred in 53.1% and 48.6% at medians of 20 and 11 months, respectively. Doxycycline did not significantly decrease the risk of Co-CCLR (p = 0.83). This risk was decreased by 14.2% with each year of age but increased with each increasing kilogram of body weight and each increasing degree of tibial plateau angle by 5.4% and 9.7%, respectively. Labrador Retrievers were not significantly predisposed (p = 0.37).

Clinical significance: At the dose regimen investigated doxycycline does not decrease the risk for Co-CCLR.

Keywords: Doxycycline; canine; cranial cruciate ligament rupture; dog; tibial plateau levelling osteotomy.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Animals
  • Anterior Cruciate Ligament / pathology*
  • Anti-Bacterial Agents / pharmacology*
  • Dog Diseases / genetics
  • Dog Diseases / prevention & control*
  • Dogs
  • Doxycycline / pharmacology*
  • Female
  • Genetic Predisposition to Disease
  • Male
  • Risk Factors
  • Rupture / prevention & control
  • Rupture / veterinary*


  • Anti-Bacterial Agents
  • Doxycycline