2.3 Feline Treatment, Anesthesia & Surgery

2.3 Feline Treatment, Anesthesia & Surgery

Feline surgical procedures, anesthetic management, and pharmacology require specialized knowledge of the species' unique anatomy, physiology, and metabolic pathways.

Anesthetic Risks & Cardiovascular Support

Felines exhibit a higher rate of anesthetic mortality compared to dogs. Unique physiological risks include a high susceptibility to hypothermia (due to a large surface area-to-body mass ratio), hypoventilation (due to small airway diameters and a high risk of laryngospasm), and fluid overload.

• Airway Management: The feline larynx is highly reactive. Intubation attempts can trigger laryngospasm, leading to complete airway obstruction. To prevent this, the clinician must desensitize the arytenoid cartilages by applying 0.1 mL of 2% lidocaine topically to the glottis prior to intubation. Endotracheal tube cuffs must be inflated with extreme care; over-inflation can easily compress the tracheal mucosa against the cartilage, leading to tracheal necrosis, tear, or rupture.
• Perfusion Maintenance: Ensuring adequate mean arterial pressure (MAP) > 60-70 mmHg (or systolic arterial pressure > 90 mmHg) is critical to maintain renal blood flow and prevent post-anesthetic acute kidney injury (AKI), especially in cats with subclinical chronic kidney disease. Felines have a lower circulating blood volume (55-65 mL/kg) compared to dogs (80-90 mL/kg), making them highly susceptible to fluid overload. Anesthetic fluid rates should be maintained at 3 to 5 mL/kg/hour of isotonic crystalloids. If hypotension occurs and is refractory to reducing the inhalant anesthetic concentration and providing conservative crystalloid boluses (e.g., 5-10 mL/kg), pharmacological support should be initiated. A constant rate infusion (CRI) of a positive inotrope, such as dobutamine or dopamine (2-10 mcg/kg/min), is indicated to improve cardiac output and restore perfusion.

Surgical Management of Common Feline Cases

Esophagostomy Tube (E-Tube) Placement

• Indications: Indicated for long-term enteral nutrition in cats with hepatic lipidosis, severe maxillofacial trauma, oral neoplasia, or chronic diseases causing anorexia.
• Technique: The cat is placed in right lateral recumbency, and the left cervical region is prepared surgically. A curved hemostat (such as a Carmalt) is passed through the mouth into the esophagus. The tip is turned laterally, pressing against the mid-cervical esophageal wall to create a visible bulge. A skin incision is made over the bulge, and the hemostat tip is pushed through the incision. The distal tip of the E-tube (typically 12-14 Fr) is grasped by the hemostat and pulled back through the incision into the oral cavity. The tube is then redirected manually down the esophagus.
• Securing and Verification: The tube is secured to the skin using a Chinese finger trap suture pattern. A lateral thoracic radiograph is mandatory to verify placement. The tip of the tube must lie within the distal esophagus, cranial to the lower esophageal sphincter (typically at the level of the 7th to 9th intercostal space). The tube must not enter the stomach, as this crosses the lower esophageal sphincter, causing gastroesophageal reflux, esophagitis, and persistent vomiting.

Perineal Urethrostomy (PU)

• Indications: Indicated for male cats with recurrent urethral obstructions that cannot be managed medically, or distal urethral strictures.
• Technique: The patient is placed in a perineal position (sternal recumbency, tail taped forward), and a pursestring suture is placed in the anus. An elliptical incision is made around the scrotum and prepuce. The penis is dissected free from its attachments, including transecting the ischiocavernosus muscles at their origin on the ischium.
• Anatomical Landmark: The dissection must proceed cranially until the bulbourethral glands are exposed. These glands mark the junction where the narrow penile urethra transitions into the wider pelvic urethra. The penile urethra is incised dorsally up to the level of the glands. The urethral mucosa is then sutured to the skin using fine monofilament suture (e.g., 4-0 or 5-0 poliglecaprone 25) in a simple interrupted pattern, creating a wide stoma.
• Complications: Post-operative urethral stricture is the most common complication, almost always resulting from failure to dissect cranially enough to reach the bulbourethral glands. Other complications include hemorrhage, wound breakdown, and an increased risk of ascending bacterial urinary tract infections.

Linear Foreign Body Surgery (Gastrotomy & Enterotomy)

• Pathophysiology: Linear foreign bodies (e.g., thread, yarn, dental floss) typically lodge under the tongue (lingual anchor) or at the pylorus. Peristalsis attempts to move the free end distally, causing the intestines to bunch up (plicate) along the string. As tension increases, the string cuts through the mesenteric border of the intestines, leading to multiple perforations and septic peritonitis.
• Technique: Anesthetized cats must have their sublingual region inspected and any lingual anchor released. A full midline laparotomy is performed. A gastrotomy is performed to release the anchor if it is lodged in the pylorus. Multiple enterotomies are made to extract the foreign body in small, manageable sections. Forcefully pulling the string from one end is strictly contraindicated, as it causes a sawing action that will lacerate the bowel. Viability of the plicated bowel is assessed by color, motility, and presence of arterial pulses. Necrotic or perforated segments require resection and anastomosis (R&A).

Feline-Specific Pharmacology

Oral prednisone is therapeutically ineffective in cats due to low hepatic activity of the converting enzyme 11-beta-hydroxysteroid dehydrogenase and poor overall absorption. Therefore, prednisolone is the mandatory choice for glucocorticoid therapy.