Table 5 Unadjusted and adjusted hazard ratios for unilateral cranial cruciate ligament (CCL) rupture generated from Cox proportional hazards model of dogs with unilateral CCL rupture (n = 24) and dogs resistant to CCL rupture (n = 81). In this survival analysis, time to event is time to first CCL rupture.

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

1.00 (0.44–2.25)

0.99

0.86 (0.37–2.00)

0.72

Gonad Exposure

 ≤ 24 months

1.0 (ref)

   

 > 24 months

0.56 (0.22–1.41)

0.22

0.66 (0.26–1.68)

0.38

Adult Height

 Tall

1.0 (ref)

   

 Short

0.22 (0.09–0.56)

0.001

0.22 (0.08–0.57)

0.002

Body Condition

 Precedent overweight

1.0 (ref)

   

 Not overweight

0.93 (0.35–2.50)

0.89

0.76 (0.26–2.21)

0.62

Reason for Gonad Removal*

 Conformation defect /Orthopedic condition

––

   

 Other

1.0 (ref)

   

Age at CCL Status Ascertainment

 13—13.5 years

1.0 (ref)

   

 > 13.5 years

0.79 (0.35–1.76)

0.56

0.98 (0.43–2.27)

0.97

  1. For each risk variable, adjusted HR includes the other five variables in a multivariate analysis. *Reason for gonad removal drops out of model because none of 24 Rottweilers with unilateral CCL rupture were categorized as conformation defect/orthopedic condition prior to gonad removal. 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. Body Condition categories: (1) overweight prior to CCL rupture (i.e., precedent overweight); or (2) not overweight prior to CCL rupture (i.e., not overweight). HR (95% CI) = Hazard Ratio and 95% confidence interval. ref = reference group.
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