This retrospective cohort study looked at 137 declawed cats, matching them with 137 non-declawed cats. Two different groups were assessed: owned cats (88 declawed, 88 non-declawed) and 98 shelter cats (49 declawed, 49 non-declawed). The purpose of the study was to assess the impact of declawing on subsequent concerns including aggression, inappropriate elimination, back pain and barbering. The study also aimed to determine the prevalence of P3 fragments remaining after declaw surgery and whether the presence of these fragments was associated with increased risk of aggression, inappropriate elimination, back pain and/or barbering.
Each cat underwent a physical examination for signs of pain and barbering by the same veterinarian (NM). Patient records of owned cats were reviewed for the previous two years to determine age, method of declaw surgery (laser, guillotine, other) and the presence of the outcomes of interest: a history of back pain and any history of behavioral changes including signs of aggression (biting), potential signs of pain (barbering) and house soiling (urinary and/or fecal soiling outside of the litter box). Radiographs of the forelimbs were obtained for each cat and submitted to a board certified radiologist for review.
Owners, clinic staff and shelter staff were not aware of the working hypotheses for the study. The radiologist was aware of the working hypotheses but was blinded to the patient medical history and physical examination findings. The association of declaw with the outcomes of interest were examined using chi2 analysis, two sample t-tests and manual, backwards, stepwise logistic regression.
A significant increase in the risk of back pain (Odds Ratio (OR) 2.9), house soiling (OR 7.2), biting (OR 4.5), and/or barbering (OR 3.06) were found in declawed cats compared to non-declawed cats.
A somewhat unexpected finding was the relatively large number of declawed cats with evidence of retained P3 fragments. Of the declawed cats included in the study, 86/137 (63%) had radiographic evidence of residual P3 fragments. The odds of back pain (OR 2.66), house soiling (OR 2.52) and aggression (8.9) were significantly increased in declawed cats with retained P3 fragments compared to those declawed cats without. While complete removal of P3 was associated with fewer adverse outcomes, operated animals were still at increased odds of biting (OR 3.0) or house soiling (OR 4.0) when compared with non-surgical controls.
Based on statistically significant findings between declawed and non-declawed cats, the authors conclude that declawing increases the risk of unwanted behaviors and may increase the risk for developing back pain. The complete removal of P3 reduces but does not eliminate the risk of adverse behavior subsequent to onychectomy. (KSD)