Complications Related to Surgical Treatment of Intervertebral Disc Disease in Dogs

Lexmaulová L., R. Novotná, P. Raušer, A. Nečas: Complications Related to Surgical Treatment of Intervertebral Disc Disease in Dogs. Acta Vet. Brno 2008, 77: 269-276. After intervertebral disk surgery we often have to deal with various complications (seizures, gastrointestinal tract (GIT) ulcerations, cystitis, and surgical wound healing problems). These complications may lead to the death of the patient. We performed clinical and laboratory investigations in 161 dogs with an intervertebral disc disease. After that, we performed a cranial (n = 31), caudal (n = 125) or both (n = 5) types of myelography at the same time, and surgery ventral slot decompression (SLOT) (n = 18) or hemilaminectomy (n = 143). During the postsurgical period we observed seizures, GIT complications, cystitis, and surgical wound healing problems or even death of the patients. These complications appeared to be related to the lesion site, the degree of clinical signs and the type of surgical procedure. In our study we found a higher incidence of seizures after cranial myelography, higher incidence of gastrointestinal (GI) complications particularly in paraplegic dogs, and a higher risk of death in patients after the SLOT surgery. The occurrence of cystitis was not significant (p = 0.5524, p = 0.1655, respectively). We consider seizures, GI ulcerations, and death the most frequent complications after intervertebral disc surgery. Their incidence depends on the lesion site and the degree of neurologic symptoms. Hemilaminectomy, seizures, gastrointestinal ulceration For a surgical procedure to be successful, it is important not only to make an early and correct diagnosis and to perform decompression as soon as possible, but also to take proper care both before and after the surgery. Postponed surgery worsens prognosis for paraplegic patients, and there is usually a need for longer recovery (Nečas 1999, 2000). In such patients, the electrostimulation test is recommend to decide if there is any chance to succeed with surgery at all (Bauer et al. 1992). During the post-surgery period we observed in patients with the intervertebral disc disease several complications (seizures, GI ulcerations, cystitis, pyelonephritis and surgical wound healing problems) that might lead to the death of the patients (Hart et al. 1997ab). The occurrence of seizures during recovery from anaesthesia is thought to be related to myelography (Roberts and Selcer 1993). The frequency of seizures is affected by the type and volume of contrast medium, type of myelography, anaesthetics, weight, and hydration status of the patient (Barone et al. 2002; Roberts and Selcer 1993; Wright and Clayton 1981). GI ulcerations usually lead to vomiting and/or bloody diarrhoea (fresh or digested). It is generally thought to be caused by using steroids in the perioperative period, particularly by dexamethasone (Hart et al. 1997b; Toombs et al. 1980). The risk of a deep ulcer and consequently, the occurrence of colon perforation increases with a slow faeces passage and with obstipation. An inflammatory response of the organism is reduced by steroids, thus soon after a clinical manifestation of colon perforation these animals die (Toombs et al. 1986). The ability to urinate can be reduced in paraplegic patients (Oliver et al. 1987; Toombs ACTA VET. BRNO 2008, 77: 269-276; doi:10.2754/avb200877020269 Address for correspondence: MVDr. Leona Lexmaulová Klinika chorob psů a koček Veterinární a farmaceutická univerzita Brno Palackého 1/3, 612 42 Brno Phone: +420 604 270 861 E-mail:[email protected] http://www.vfu.cz/acta-vet/actavet.htm and Bauer 1993). This might predispose the animals to urinary tract infections (Amsellem et al. 2003). If the lesion is localized cranially from L4, the tone of proximal urethra is increased (so called “upper motor neuron bladder syndrome”) and urine cannot by easily squeezed out of the urinary bladder. If the lesion is localized more caudally (behind L4), urine can be easily squeezed out of the urinary bladder, because the tone of proximal urethra is decreased and urinary bladder is usually atonic (so called “lower motor neuron bladder syndrome”) (Amsellem et al. 2003; Oliver et al. 1987). In paraplegic patients we usually do not observe signs of dysuria or pollakiuria; we only observe haematuria. Antibiotic treatment should be initiated after urine culture and known pathogen sensitivity (Hart et al. 1997a). Surgical wound healing problems may include oedema, bleeding, haematoma, seroma, infection and dehiscence. Oedema is the most common complication; however, it usually does not require any treatment. The risk of haemorrhage and haematoma of the surgical wound can be higher when non-steroidal anti-inflammatory drugs (NSAIDs) have been given. Seroma is not usually clinically significant and does not need any therapy; however, it is rich in protein and predisposed to infection, which is a serious but rare complication after spine surgery (Hart et al. 1997b). In recumbent patients there is always the risk of decubital ulcers and intertrigo (Hart et al. 1997b). These problems might be prevented by placing the patients on a clean absorbent pad. Thus, intertrigo in the anal, vulvar, and caudal thigh regions caused by irritation from faeces and urine can be avoided. As a preventive or therapeutic measure, it is possible to apply ointment on the anal and vulvar regions. It helps to maintain the animals’ welfare (Oliver et al. 1987). Death of the animal may be caused by a wide range of conditions. Depression, apnoea, and arrhythmias may occur while the contrast medium enters the subarachnoidal space (Harvey et al. 1996). If compared with thoracolumbar vertebral surgery, arrhythmias appear to be more frequent in cervical vertebral surgeries (Coates 2000). GI ulceration might progress into gut perforation, particularly in the colon. Consequently, septic peritonitis and sepsis may follow (Toombs et al. 1980, 1986). The purpose of this study was to document all complications during the perioperative and postoperative time in patients with an intervertebral disc disease after the surgical procedure based on decompression. In addition, we tried to find whether the observed complications (seizures, GI complications, cystitis, bleeding and death) are related to the lesion site and the degree of neurological signs. Materials and Methods Study animal group Between 2000 and 2002 we performed surgeries in 161 dogs with an intervertebral disc disease at our clinic (94 males and 67 females, aged 7.2 ± 4.23 years, weighing 10.7 ± 6.75 kg). All the patients were vaccinated and dewormed. Neurological examination was performed and the degree of clinical signs and localization of the lesions were determined. In 18 patients we found neurological deficits in thoracic limbs and in 143 dogs in pelvic limbs. According to the degree of clinical signs, the patients were divided into groups I III when the cervical spine was affected (I first episode of cervical pain, II recurrent pain, III pain with neurological deficit) and groups I IV when thoracolumbar spine was affected (I first episode of back pain, II recurrent pain and/or mild to moderate paraparesis, III severe paraparesis, IV paraplegia) (Toombs and Bauer 1993). We performed blood chemistry and haematology examination in all patients. Experimental procedure and design After a physical and neurological examination we placed the intravenous catheter into the cephalic antebrachial vein or lateral saphena vein and collected a blood sample for routine blood tests (biochemistry and haematology), emptied the urinary bladder and performed a fast urinoanalysis using a screening test strip. These patients were then sedated by intravenously administered medetomidin (Domitor inj., Pfizer, Belgium) at the dose of 0.02 mg/kg and buprenorfine (Temgesic inj., Reckitt and Colman, U.K.) at the dose of 0.01 mg/kg in one syringe. As induction to general anaesthesia we used propofol (Propofol Abbott inj., Abbott Lab., USA) at the dose of 1 2 mg/kg. General anaesthesia was based on the application of oxygen and nitrous oxide (1 : 1) with isoflurane (Forane, Abbott Lab., USA) at the concentration of 0.5 1.5 vol.% (inhalation anaesthesia machine Anemat N8, Chirana, Czech Republic). We closely monitored the patient’s heart and respiratory rate, end-tidal 270