Waterhouse–Friderichsen syndrome in a cat with Klebsiella spp. infection

Objective: TodescribeacaseofWaterhouse–Friderichsensyndromeofadrenocortical failure in a cat with Klebsiella spp. infection. Case Summary: A 12-year-old male neutered domestic short-haired cat was referred for respiratory failure requiring mechanical ventilation. The cat remained comatose despite successful weaning from the ventilator and developed a Klebsiella pneumoniae pneumonia. On day 4 of hospitalization, the cat acutely deteriorated with profound hypotension, azotemia, and hyperkalemia, which rapidly progressed to cardiac arrest. Necropsy findings revealed massive adrenal hemorrhage and intralesional bacteria, termed Waterhouse–Friderichsen syndrome. Waterhouse–Friderichsen syndrome was suspected to have been the cause of acquired adrenocortical insufficiency and sudden death of the cat.

TA B L E 1 Venous blood gas, acid base and electrolyte analysis at various time points of hospitalization in a cat with suspected Waterhouse-Friderichsen syndrome 0 a 12  Initial emergency database including venous blood gas analysis b revealed an acidemia and hyperglycemia (Table 1) Oxygen therapy was provided using a commercial oxygen kennel e (FiO 2 0.6). Analgesia was initially provided with fentanyl f (5 µg/kg/h IV) and ketamine g (0.3 mg/kg/h IV) was added due to persistent tachypnea and increasing pain score. Repeat venous blood gas 12 h later revealed hypercapnia (Table 1). Due to hypercapnia and concern for respiratory fatigue, the cat was anesthetized with midazolam, h fentanyl, and propofol i and mechanical ventilation (MV) j was initiated. MV was initiated using an assisted pressure-controlled mode with a positive end-  Ropivacaine dosing was then continued every 6 hours.
After these procedures, all IV anesthetic drugs were discontinued and ventilatory support was removed. The cat remained intubated and was spontaneously ventilating but remained comatose. This state persisted despite reversal of the midazolam and the opioids with flumazenil o and naloxone, p respectively. The cat was hemodynamically stable and oxygenating well with an arterial oxygenation saturation of 98%

DISCUSSION
This report describes a case of Waterhouse-Friderichsen syndrome in a cat resulting in presumed adrenocortical insufficiency and death.
Acute hemorrhagic necrosis of the adrenal gland and clinical adrenal insufficiency termed Waterhouse-Friderichsen syndrome is a rarely reported condition in people that is associated with a high morbidity and mortality. 1   rhage. This is further compounded by platelet aggregation and thrombosis secondary to increased catecholamine release from the adrenal medulla. 3,9,10 Primary hypoadrenocorticism, defined as the deficiency of glucocorticoid and/or mineralocorticoid secondary to destruction of the adrenal gland, is predominantly described in dogs as a result of immune-mediated destruction of the adrenal gland and has less commonly been associated with neoplasia, granulomatous disease, and hemorrhage. [11][12][13] Primary hypoadrenocorticism has rarely been reported in cats. 14 Antemortem biochemical findings reported to be supportive of a diagnosis of hypoadrenocorticism include azotemia, hyponatremia, hyperkalemia, Na:K ratio < 26, and ECG findings including sinus bradycardia and atrial premature complexes. 11,15 These clinicopathological findings can also be seen with acute kidney injury (AKI). Therefore, in light of cat's age, presence of renal infarctions, and meloxicam use, AKI was also considered as a differential alongside an adrenocortical crisis. However, necropsy findings were not compatible with AKI.
Adrenal hemorrhage can lead to adrenal dysfunction and has been previously considered as one of the many etiological causes of critical illness-related corticosteroid insufficiency (CIRCI). 16  In the authors' opinion, the rapidity of decline in a previously hemodynamically stable animal was more consistent with a peracute primary adrenocortical crisis than CIRCI. A basal cortisol, adrenocorticotrophin hormone stimulation, and response to treatment with hydrocortisone would have been required to confirm the diagnosis of adrenocortical dysfunction antemortem. Unfortunately, the cat's condition deterio-

CONCLUSION
To the authors' knowledge, this is the first report in veterinary medicine of bilateral massive adrenal hemorrhage, termed Waterhouse-Friderichsen syndrome secondary to sepsis. This condition led to a rapid clinical deterioration and cardiac arrest in this cat. Awareness of this condition may allow for earlier recognition and appropriate treatment of this syndrome antemortem.