Table 4 Unadjusted and adjusted hazard ratios for bilateral cranial cruciate ligament (CCL) rupture generated from Cox proportional hazards model of dogs with bilateral CCL rupture (n = 18) and dogs resistant to CCL rupture (n = 81).

From: Correlates of estimated lifetime cruciate ligament survival inform potential rupture risk reduction strategies: findings from the Exceptional Aging in Rottweilers Study

Variable

Unadjusted HR (95% CI)

p-value

Adjusted HR (95% CI)

p-value

Sex

 Male

1.0 (ref)

   

 Female

2.36 (0.78–7.18)

0.13

2.89 (0.92–9.12)

0.07

Gonad Exposure

 ≤ 24 months

1.0 (ref)

   

 > 24 months

0.05 (0.02–0.19)

 < 0.001

0.05 (0.02–0.20)

 < 0.001

Adult Height

 Tall

1.0 (ref)

   

 Short

0.19 (0.06–0.56)

0.003

0.30 (0.10–0.94)

0.04

Body Condition*

 Precedent overweight

1.0 (ref)

   

 Not overweight

––

   

Reason for Gonad Removal

 Conformation defect/Orthopedic condition

0.77 (0.10–5.77)

0.80

0.33 (0.04–2.75)

0.30

 Other

1.0 (ref)

   

Age at CCL Status Ascertainment

 13–13.5 years

1.0 (ref)

   

 > 13.5. years

0.57 (0.22–1.47)

0.24

0.40 (0.15–1.09)

0.08

  1. In this survival analysis, time to event is time to second CCL rupture. For each risk variable, adjusted HR includes the other five variables in a multivariate analysis.
  2. *Body condition drops out of model because none of 18 Rottweilers with bilateral CCL rupture were categorized as precedent overweight prior to the time of first rupture or became overweight during the time prior to the second rupture. Gonad exposure categories: ≤ 24 months = early endocrine disruption; > 24 months = avoidance of gonad removal during the first 24 months of life. Tall females ≥ 61.0 cm; Tall males ≥ 64.8 cm. HR (95% CI) = Hazard Ratio and 95% confidence interval. ref = reference group.
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