Duke is a five-year-old MN Rhodesian ridgeback who was referred to Northside Veterinary Specialists (NVS) for acute collapse. A dental had been performed one week prior to this, and he had had a prolonged recovery.
He was found in the garden, lying on the ground and moaning, and was immediately taken to his regular vet where he had full bloods run which showed no specific abnormalities, was given 0.1mg/kg Butorphanol IM and was referred to NVS for further investigation and treatment.
On presentation he was ambulatory but weak, had injected to muddy mucus membranes with a capillary refill time (CRT) of two seconds and a heart rate of 180 BPM with poor peripheral pulses. He was uncomfortable in his abdomen but did not have overt abdominal distension. An Abdominal Focused Assessment with Sonography in Trauma (AFAST) was performed which showed no Free Abdominal Fluid (FAF) and a large gas distended stomach. A right lateral cranial abdominal radiograph was performed which confirmed Gastric Dilation Volvulus (GDV) and severe microcardia and collapsed caudal vena cava consistent with hypovolaemia.
Further pre anaesthetic blood testing showed PCV 48 TP 64, Lactate 1.4, normal coagulation times and electrolytes. He was given 1 litre (approx. 25ml/kg) of Hartmanns over 20 minutes and started on a Fentanyl CRI at 2ug/kg/hr. He did not have needle decompression pre surgery as his stomach was too far under the rib cage to reach. In surgery he had an uneventful derotation and incisional gastropexy. His stomach had minimal devitalisation and he did not need a splenectomy. He had an uneventful recovery from anaesthetic and was maintained on IV Hartmanns, fentanyl CRI and Cephazolin.
Overnight he deteriorated to having profuse watery then haemorrhagic diarrhoea, hypotension and hyperlactatemia with partial response to 10ml/kg Hartmanns fluid bolus. He was laterally recumbent and had cold extremities. On AFAST Diaphragmatic Hepatic (DH) view the caudal vena cava were flat suggesting that he was hypovolaemic.
He had a urinary catheter placed to monitor his urine output and was given further fluid boluses during the day up to a total of 1300mls (approx. 35mls/kg). His antibiotics were upgraded to four quadrant coverage in case of bacterial translocation and sepsis (Piperacillin Tazobactam 50mg/kg slow IV every 8 hours and Metronidazole 10mg/kg IV every 12 hours), and was started on Paracetamol (10mg/kg q 8hrs IV) for analgesia so that his Fentanyl could be stopped due to concern over it dropping his blood pressure further. He initially responded to the fluid resuscitation but had to be started on a Noradrenaline CRI (0.1ug/kg/min) that afternoon to maintain his blood pressure. Overnight he improved and was weaned off the Noradrenaline CRI. The next morning he started eating, was transitioned onto oral medication and went home 24 hours later.
He then represented to his regular vet 24 hours after discharge with lethargy, inappetance, a mild cough and black tarry faeces. He had full bloods run there which showed a Neutrophilia (28.58 x 109/L), Monocytosis (2.98 x 109/L) with a Na/K ratio of 26. He was referred back to us for ongoing care.
At this point Hypoadrenocorticism (Addison’s disease) was suspected and an in-house ACTH Stimulation test was performed which showed a pre and post stimulation cortisol level of < 14nmol/l, confirming the diagnosis. He was also found to be profoundly hypovolaemic and had mild aspiration pneumonia on thoracic radiographs. He was given 0.2mg/kg dexamethasone IV, had a 10% fluid resuscitation plan overnight and was restarted on IV Piperacillin Tazobactam for the aspiration pneumonia.
In hindsight, Addison’s could have been suspected earlier for his condition. As corticosteroids are needed to maintain vascular tone, his inability to maintain his blood pressure post GDV surgery without an obvious cause of sepsis, in combination with the slow recovery from his dental a week before, was suspicious. The first time he showed electrolyte abnormalities suggestive of Addison’s was the day that he was diagnosed, but even that day he had an inflammatory leukogram which was not classic for it.
It can be speculated that Duke was borderline for Addison’s pre GDV and then developed Critical Illness Related Corticosteroid Insufficiency (CIRCI) leading to an Addisonian Crisis.
Addison’s disease can be a challenging diagnosis as it is known as the ‘Great Pretender’, and should be considered in patients with vague or recurrent gastrointestinal symptoms. Not all cases of Addison’s will have classic electrolyte abnormalities, such as Atypical Addison’s cases which only have glucocorticoid deficiency and borderline cases which are not in overt crisis at presentation.
CIRCI (previously known as Relative Adrenal Insufficiency) is a condition that can occur in patients that have severe illness, such as sepsis. They have a combination of lack of production and resistance to corticosteroids which lead to inadequate levels for the stress response they experience. Glucocorticoids are needed to maintain vascular tone, so CIRCI should be suspected in critical patients with low blood pressure which is refractory to IV fluids and vasopressors.
Duke went on to make a full recovery and has been stable on Desoxycorticosterone pivalate (DOCP) injections and Cortisone acetate (Cortate) tablets.
Dr Lucy Kirton BVetMed MANZCVS (VetECC) MRCVS Emergency veterinarian
Dr Kirton graduated from the Royal Veterinary College, London, in 2004. She worked initially in mixed practice but quickly moved into small animal general practice. She came to Australia in 2011, quickly settling in Sydney.
Having developed an interest when working on Sydney’s Northern Beaches, providing critical care to tick paralysis patients, she began working in emergency practice in 2013, initially at the Small Animal Specialist Hospital (SASH), and then Northside Emergency Veterinary Service (NEVS) in 2016.
She passed her ANZCVS memberships in Emergency and Critical Care in 2014 and was a membership examiner in 2017 and 2018. She has a particular interest in critical care, ventilation, cardiopulmonary resuscitation (CPR) and training. She became a RECOVER CPR trainer in 2017 and is a director in FlexiVet Training Pty Ltd which offers small animal emergency and CPR training.
Dr Kirton lives in the Sydney Hills District with her partner and stepdaughter. In her spare time, she enjoys sailing and yoga.