A 3-month-old entire female British Shorthair cat was referred to the Queen Mother Hospital for Animals for further management of thermal burns. The kitten had fallen into a bath of scalding water for approximately 30 s before she was removed, and first aid was administered by placing her in cold water for approximately 10 mins. In the UK, hot water is stored at 60 C to kill Legionella species. Although the temperature of the scalding bath water is not known, given that the bath was being filled exclusively with hot water the temperature was likely to have been between 45oC and 55oC.
The kitten presented to the primary care practice obtunded, vocalising and shivering. The haircoat was wet, with erythematous skin and sloughing from the digital pads and anal mucosa. The respiratory rate was 20 breaths per min, heart rate was 170 beats per min and mucous membranes were pink and moist, with a capillary refill time <2 s. Thoracic auscultation was unremarkable. The kitten was assessed as euhydrated. The rectal temperature was 37.9oC. Severe pain limited further examination. Methadone was administered intramuscularly (IM) at 0.3 mg/kg (Synthadon; Animalcare).
The kitten was sedated with medetomidine at 25 microg/kg IM (Domitor; Vetoquinol) to facilitate intravenous (IV) catheter placement. The level of sedation was insufficient after 15 mins and a second dose of medetomidine at 20 microg/kg IM was administered, which provided suitable sedation for IV catheter placement. Following IV placement, cefuroxime 15 mg/kg IV (Zinacef; GlaxoSmithKline) was administered. IV isotonic crystalloid therapy was initiated at 6 ml/kg/h (compound sodium lactate; Aquapharm) for approximately 2 h prior to referral.
The kitten presented to the referral hospital approximately 6 h after sustaining the burn trauma. On arrival, the kitten was obtunded, overtly painful, vocalising and resistant to handling. An IV fentanyl bolus (Fentadon; Dechra) of 2 microg/kg was administered and continued as a constant rate infusion (CRI) at 4 microg/kg/h. Limited physical examination confirmed respiratory and cardiovascular stability. Measurement of blood pressure and rectal temperature were not tolerated owing to pain and distress. The kitten was euhydrated and weighed 1.53 kg with a body condition score (BCS) of 4/9 and muscle condition score of 2/3.
Initial point-of-care venous blood gas and metabolite analysis identified mild hyperglycaemia attributed to stress (8.5 mmol/l; reference interval [RI] 4.7-7.3 mmol/l [156.6 mg/dl; RI 84.6-131.4 mg/dl]); all other results were within the RIs (Table 1). IV isotonic crystalloid therapy (compound sodium lactate) was restarted at 6 ml/kg/h. Throughout hospitalisation, IV potassium chloride (Hameln) was supplemented as required by adding it into the crystalloid fluid bag.
A modified Colorado State University Medical Center Feline Acute Pain Scale score of 9/12 prompted escalation of analgesia. IV ketamine (Anaestamine; Animalcare) 0.5 mg/kg followed by 0.2 mg/kg/h CRI and IV medetomidine (Medetor; Virbac) 0.1 microg/kg followed by 0.5-1 microg/kg/h CRI were introduced sequentially to achieve a pain score of 2-4/12. This multimodal analgesia protocol was continued for 3 days and then gradually weaned as guided by serial pain scoring.
General anaesthesia was performed following initial stabilisation within 2 h of admission. The kitten was premedicated with midazolam 0.2 mg/kg IV (Hyponovel; Roche) and anaesthesia was induced with propofol (PropoFlo; Abbot) administered incrementally to effect (total dose 2.5 mg/kg). Anaesthesia was maintained with isoflurane delivered in 100% oxygen. The haircoat was clipped, revealing scalding and erythema of the ventral thorax, abdomen, thoracic and pelvic limbs, and perineum, with areas of ulceration (Figure 1). The head, neck, oral cavity and corneas were unaffected.
The extent of thermal injury was approximated to be 80% of the total body surface area (TBSA) based on the 'rule of nines'. The burn injury was classified as deep partial thickness (second degree). Ulcerated areas were cleaned with dilute iodine; antimicrobial cream was not applied as the lesions were small and superficial. The patient was instrumented with a central venous catheter, urinary catheter and oesophagostomy feeding tube (O-tube); correct placement was confirmed with thoracic radiography. The O-tube was placed as described by Mazzaferro, and the insertion stoma was covered with a sterile dressing and checked twice daily for signs of infection. Pyrexia of 39.7oC was documented after the kitten had recovered from general anaesthesia.
Prior to sustaining the thermal burn injury, the kitten was being fed a mixture of complete and balanced wet/dry kitten foods appropriate for growth. Daily resting energy requirement (RER) was calculated to be 96 kcal/day using the formula RER = 70 x body weight (kg)0.75. The most recent daily weight was used to calculate the daily RER during hospitalisation. A veterinary liquid diet (Gastrointestinal High Energy; Royal Canin) was fed as a CRI within 12 h of admission at 50% of the kitten's calculated RER (48 kcal). The kitten initially showed no interest in voluntary intake of food and provision of enteral nutrition via the O-tube was incrementally increased to 100% (96 kcal/day) within the first 48 h (Figure 2).
The therapeutic liquid diet (Gastrointestinal High Energy; Royal Canin) was chosen for ease of administration and high calorie content. It was used for all O-tube feeds and administered as a CRI. Although marketed for dogs, this liquid diet met the minimum nutritional content recommended for growing kittens for the majority of nutrients (Table 2). The protein, calcium and phosphorus levels of this diet were slightly below the minimum content recommended for growing kittens. In order to mitigate this deficiency, the kitten was also offered a canned wet food diet specifically formulated to support growth in cats (Hill's Science Plan Kitten) at six intervals throughout the day.
Prior to planned anaesthesia and surgical procedures, the kitten received a final feed the night before at 2 am, after which food was withheld and the O-tube CRI stopped. Feeding was restarted once the kitten had recovered from anaesthesia and the frequency of feeds and CRI volume adjusted to ensure the daily calorie target was met. The kitten remained euhydrated based on clinical examination throughout hospitalisation; therefore, fluctuations in body weight were not attributed to changes in fluid balance.
Haematology and biochemistry panels sampled on admission revealed a non-regenerative mild anaemia, neutropenia, hypoalbuminaemia, hypocholesterolaemia and increased alanine aminotransferase (ALT) activity (Table 1). On day 2, the kitten remained pyrexic at 39.9oC. The urinary catheter was removed and the central venous catheter was replaced as it had been removed by the patient. Pyrexia persisted despite new vascular access. No erythema or discharge of the O-tube site was detected on daily assessment. Urinalysis indicated no evidence of urinary tract infection and urine culture demonstrated no microbial growth. IV potentiated amoxicillin 20 mg/kg q8h (Augmentin; GlaxoSmithKline) was initiated on day 3.
On day 3, the kitten started to eat small quantities of kitten food (Hill's Science Plan Kitten) when offered by hand. The calories ingested voluntarily were minimal and O-tube feeding continued at 100% of the calculated RER. Neutropenia resolved on day 4 (Table 1); however, the pyrexia persisted, with the rectal temperature fluctuating between 39.3oC and 40.5  C. In the absence of documented infection, the pyrexia was attributed to severe systemic inflammation. Antibiotics were continued due to the severity of the skin lesions (Figure 3). Biochemistry revealed static hypoproteinaemia, hypomagnesaemia, improved ALT and increased creatine kinase activities (Table 1). Magnesium was not supplemented or reassessed in the absence of clinical signs or associated electrolyte derangements consistent with hypomagnesaemia. Blood glucose remained mildly increased throughout hospitalisation (Table 1).
Between admission and day 4, the kitten lost 80 g (5.2% body weight loss), decreasing to 1.45 kg. On day 4, the kitten received a total of 120 kcal (130% of its calculated RER for the most recent daily body weight), of which 36 kcal (30%) was voluntary intake of kitten food. By day 6, the kitten's calorie intake increased to 240 kcal/day (260% of the calculated RER for the most recent daily body weight), 120 kcal (50%) of which was achieved via voluntary intake. The kitten's appetite continued to improve and by day 7 it was eating 96 kcal/day (104% of its calculated RER), and also tolerating 144 kcal/day (157% of calculated RER) via the O-tube. Between days 4 and 8 of hospitalisation, the kitten's body weight decreased further to 1.40 kg (3.5% body weight loss). On day 8 of hospitalisation, general anaesthesia was planned to facilitate wound debridement (Figure 4); thereafter, silver sulfadiazine cream (Flamazine; Smith&Nephew) was applied daily. On day 9, voluntary food intake had increased to 120 kcal/day (133% of calculated RER using the most recent daily body weight), which was matched by O-tube feeding to bring the total daily calorie intake to 240 kcal/day (266% of the calculated RER).
On day 11, general anaesthesia was performed to facilitate extensive debridement of the more severely affected left inguinal area and hindlimb, and to perform an epidural consisting of 0.1 mg/kg morphine (Morphine Sulfate; Macarthys Laboratories) and 1.5 mg/kg ropivacaine 0.25% (Naropin; AstraZeneca) to provide regional anaesthesia postoperatively. This enabled de-escalation of systemic analgesia from fentanyl 1-5 microg/kg/h CRI to methadone 0.1-0.2 mg/kg IV q4h (Comfortan; Dechra). On day 13, buprenorphine (Buprecare; Animalcare) 0.01-0.02 mg/kg IV q6h, gabapentin (Gabapentin; Milpharm) 8 mg/kg PO q12h and meloxicam (Metacam; Boehringer Ingelheim) 0.05 mg/kg IV q24h were introduced.
Throughout days 9-12 of hospitalisation, the kitten's total calorie intake was gradually increased. However, voluntary intake did not exceed 120 kcal/day (133% of the calculated RER), despite the kitten being offered in excess of this amount. As such, in order to increase voluntary intake further, 4 g of veterinary therapeutic instant diet powder (Convalescence Support; Royal Canin) was added to all meals offered. This increased voluntary calorie intake to approximately 145 kcal/day (161% of the calculated RER), with a minimal increase in the volume of food ingested. In addition, 225 kcal/day (250% of the calculated RER) was provided via the O-tube CRI. This resulted in the kitten receiving a total of 315 kcal/day (350% RER) by day 12. Despite increased nutritional provision, between days 8 and 12 of hospitalisation the kitten lost a further 50 g of body weight (3.6% body weight), decreasing to 1.35 kg.
On day 14 of hospitalisation, a new heart murmur was documented. Echocardiography did not reveal underlying structural disease or changes consistent with endocarditis. The murmur was deemed to be haemic secondary to anaemia (Table 1). Cardiac troponin I was mildly increased (0.4 ng/ml; RI <0.04). The mild increase in cardiac troponin I concentration was attributed to myocardial injury related to systemic inflammation.
While hospitalised, the kitten received IV fluid therapy (IVFT) at 5-6 ml/kg/h based on regular assessment of hydration status, fluid intake and losses. On day 13, IVFT was decreased from 5 ml/kg/h to 3 ml/kg/h. The following day, IVFT was reduced further to 1 ml/kg/h before being discontinued on day 15. Fluid therapy was discontinued as clinical assessment indicated that enteral fluid intake was sufficient to meet the kitten's needs and significant losses were not occurring.
Dyspnoea developed on day 15 of hospitalisation and the kitten was placed in an oxygen kennel set at 60% fraction of inspired O2. Thoracic radiographs identified cardiomegaly without infiltrative pulmonary disease. Point-of-care ultrasound identified diffuse pulmonary B lines on day 16 of hospitalisation. Pulmonary B lines are associated with peripheral interstitial-alveolar disease of varying aetiology. Acute respiratory distress syndrome was suspected, although thromboembolism or aspiration pneumonia could not be excluded. The respiratory signs resolved within 7 days of occurring and oxygen therapy was de-escalated.
The kitten remained persistently pyrexic since admission. On day 16, septicaemia was diagnosed when repeat haematology documented phagocytosis of bacterial cocci. Blood cultures were obtained prior to escalation of antibiosis. The kitten had been receiving potentiated amoxicillin (Augmentin; GlaxoSmithKline) 20 mg/kg q8h since day 3 of hospitalisation. IV imipenem (Primaxin; Merck Sharp & Dohme) 10 mg/kg q8h was introduced concurrently pending blood culture results. Growth of multidrug-resistant Escherichia coli and Pseudomonas aeruginosa (resistant to potentiated amoxicillin) was reported after 48 h incubation from enrichment culture. Both isolates were susceptible to imipenem, which was continued for a total of 5 days. Potentiated amoxicillin was discontinued once the culture results had been received. The kitten's pyrexia resolved within 24 h of initiating imipenem (Primaxin; Merck Sharp & Dohme).
Throughout days 12-17 of hospitalisation, the kitten's total calorie intake was increased to 385 kcal/day (438% of the calculated RER) by increasing the calories fed via the O-tube. Calorie consumption is reported in relation to the kitten's RER for ease of comparisons throughout this paper as the RER calculation is only dependent on body weight. On day 17, the O-tube was prematurely removed by the patient. The kitten was able to maintain a voluntary calorie intake of 289 kcal/day (328% of the calculated RER) and its weight remained static. Between days 12 and 24, the kitten's body weight gradually increased by 50 g to 1.4 kg (3.6% of its current body weight). Cessation of weight loss indicated that its apparent energy requirements were being met.
The kitten was discharged from the hospital on day 24. Dietary recommendations at discharge were to feed a minimum of 289 kcal/day (328% of the calculated RER) of a complete and balanced growth diet (Hill's Science Plan Kitten) and increase the amount of food offered if there was a decrease in body weight. Body weight was 1.4 kg vs 1.53 kg on admission. BCS was 3/9 vs 4/9 on admission and the muscle condition score had decreased from 2/3 to 1/3.
There was incomplete healing of the thermal burns at discharge. Medication dispensed included sublingual buprenorphine 0.02 mg/kg q8h (Buprecare; Animalcare), oral meloxicam (Metacam; Boehringer Ingelheim) 0.05 mg/kg q24h and gabapentin (Gabapentin; Milpharm) 8 mg/kg q12h, to be discontinued at the discretion of the primary care veterinary surgeon. Clinical reassessment was performed at the primary care practice 5 days after discharge (Figure 5).
At follow-up 18 months post-injury the kitten weighed 3.97 kg with a BCS of 4/9 and muscle condition score of 2/3. In addition, there had been complete healing of the deep partial-thickness burns and full regrowth of hair.