Effect of doxycycline on stifle lameness: a preliminary clinical observation in twelve dogs

The clinical efficacy of oral doxycycline was evaluated in twelve dogs with stifle arthritis and a presumptive diagnosis of early cruciate disease. Doxycycline (2.5-4.5 mg/kg once daily) was administered orally for 3 to 8 weeks. Eight dogs, who presented prior to the treatment with clinical signs of 4 weeks or fewer duration (group B), had a good response to doxycycline, whereas four dogs with a longer history of lameness (group A) had a poor response. The follow-up periods ranged from 2 to 12 months after discontinuation of the doxycycline treatment (median=6.5 months, 3 months in group A, and 9.5 months in group B). There was a significant correlation between the duration of lameness and the subjective grading of clinical improvement. In 68% of these cases of dogs with stifle arthritis (8/12), the oral administration of doxycycline resulted in the improvement of lameness, even after discontinuation of doxycycline. Careful selection of patients based on the duration of their lameness appears to be crucial in order to achieve a positive outcome.