Retrospective Evaluation of Anesthetic–Analgesic Protocols in Cats with and Without Transient Myocardial Thickening Following Gonadectomy

Transient myocardial thickening (TMT) is considered a reversible feline cardiac disease that initially mimics hypertrophic cardiomyopathy. The exact etiopathogenesis remains unknown and is likely multifactorial. General anesthesia and surgery may contribute to the development of TMT in predisposed patients due to systemic inflammation, perioperative stress, surgery itself, anesthetic management, and individual susceptibility. Additionally, inadequate analgesia could result in pain, which triggers a stress response. This stress response could stimulate endogenous catecholamine release and facilitate the development of TMT. In this retrospective study, anesthetic and analgesic protocols were compared between cats with and without TMT following gonadectomy. The study group consisted of 15 cats that presented with congestive heart failure after recent anesthesia and were later suspected of or diagnosed with TMT. The control group consisted of 300 cats without TMT after gonadectomy. All cats were considered healthy prior to gonadectomy based on physical examination; no echocardiography was performed prior to anesthesia. All cats in the TMT group were anesthetized with ketamine and an alpha-2 agonist, which was medetomidine in 14/15 (93.3%) and dexmedetomidine in 1/15 (6.7%) of the cats. In the control group, all cats were anesthetized with ketamine and dexmedetomidine. The ketamine dose was significantly higher (p < 0.001) in the TMT group compared to the control group, with a median dose of 6.78 mg/kg (4.52–10.34) and 4.29 mg/kg (2.08–6.45), respectively. The doses of the alpha-2 agonist and atipamezole were not significantly different. The most commonly administered non-steroidal anti-inflammatory drug was meloxicam in 83.3% of the study group cats and 98.7% of the control group cats. The dose of meloxicam was significantly lower (p < 0.001) in the study group compared to the control group, with median doses of 0.2 mg/kg (0–0.3) and 0.29 mg/kg (0–0.38), respectively. In the control group, 93.0% of the cats received buprenorphine, and 75.0% of males received intratesticular lidocaine. None of the cats in the study group received buprenorphine or intratesticular lidocaine during the procedure. Additionally, oxygen supplementation was significantly different (p < 0.017), and lack of oxygen was associated with the development of TMT. Anesthetic protocols between the two groups were significantly different. However, it is important to note that not all observed complications can solely be attributed to anesthetic or analgesic differences; effects might also be due to different perioperative circumstances.