Emergency presentations in exotic patients are as unique and varied as exotic species themselves. While the well-known trope of exotic patients presenting in advanced states of disease due to hiding symptoms of illness is commonplace, exotic patients also present with a variety of emergency presentations. Some of these may be the result of misadventure or predation from wildlife or other animals in the house, and some may be acute traumatic events. In the majority of cases, whether an acute emergency or chronic disease with decompensation, most of these patients will present in shock and require intensive management.
Many exotic pets presenting in shock or following trauma are able to be treated effectively with appropriate management.
In an ideal situation, a clinic or hospital will be prepared to receive emergencies involving exotic patients. Many presenting issues can be managed in a similar way to canine and feline patients, with the same equipment already available in the clinic.
Being prepared means the team understands how to manage exotic emergencies and how to plan for the patient before arrival. In most cases, the client will contact the reception team prior to attending the veterinary practice, which gives the clinical team time to organise the necessary equipment. However, sometimes patients arrive without prior notice, so it can be useful to have an emergency kit available for these situations and to make sure the practice is ready to receive emergencies.
On presentation, exotic patients should be triaged immediately, either by a veterinarian or a registered veterinary nurse.
In an ideal situation, one staff member should be triaging and beginning stabilisation while another takes a thorough history. Clinical history is incredibly important when treating debilitated exotic patients as many conditions are husbandry-related, especially in reptiles (Hildreth, 2016).
Initially, a hands-off examination should be performed unless the patient requires lifesaving treatment immediately, for example stopping an active haemorrhage. If patients are severely dyspnoeic or weak, the entire carrier can be placed inside a warming incubator and oxygen provided (Hildreth, 2016).
Shock is difficult to assess in some taxa unless the patient is severely debilitated. Physical examination parameters to determine dehydration and shock in small mammal, avian and reptilian species are poor and unreliable (Parkinson, 2023; Vanderhasselt et al., 2013) unless the condition is severe (Figure 1). For example, in one study, tachycardia was not observed in mallard ducks until 25 to 45 percent of circulating blood volume was depleted (Lichtenberger et al., 2009), while in another study on pigeons, no clinical signs were observed with a 60 percent loss of circulating blood volume (Roberts, 2016).
In avian patients with dull mentation, inadequate cerebral perfusion and therefore hypovolaemic shock should be considered (Parkinson, 2023). Due to their ability to shunt blood via the renal portal system, reptiles are able to maintain cardiac output even in the face of shock and thus may not show any clinical signs (Roberts, 2016).
When haemorrhage has occurred, the patient is usually hypovolaemic and hypoperfused. Mammalian patients can end up in hypovolaemic shock when 10 to 15 percent of the blood volume is lost (Linklater, 2018). However, avian patients have been shown to withstand larger volumes of blood loss – up to 50 percent of their circulating blood volume (Wernick et al., 2013). This contributes to the mobilisation of interstitial fluid in avian patients in order to preserve blood pressure (Ploucha et al., 1981). Snakes have also been shown to mobilise large volumes of interstitial fluid by restoring up to 90 percent of a deficit within two hours (Smits and Lillywhite, 1985).
In general, when a patient is in hypovolaemic shock, fluid therapy should be administered intravenously or intraosseously. Further, when a patient is dehydrated, fluids can be administered orally, subcutaneously, intravenously or intraosseously (Parkinson, 2023). However, species differences require clinicians to make decisions on how fluid therapy will be administered.
In smaller patients, intravenous access may not be possible (Figure 2), or in other patients, placing an intravenous cannula may not be possible without sedation or general anaesthesia, which needs to be clinically justified in a hypovolaemic and likely hypotensive patient. Intraosseous cannulas are not technically difficult to place but can be painful, therefore thought needs to be given to whether an intraosseous cannula will be tolerated by the patient.
In non-mammalian patients, the ability to mobilise large volumes of interstitial fluid to maintain blood pressure means those presenting in hypovolaemic shock have likely also used the entirety of their interstitial fluid. It is, therefore, likely they will have lost the equivalent of their entire blood volume in fluid before entering shock (Parkinson, 2023).
The consequence of this is that the fluid resuscitation methods used commonly in mammalian medicine (eg administering a quarter shock bolus of crystalloids) may not be appropriate in these patients as they may require more than their circulating blood volume in fluid therapy. In addition, non-mammalian patients’ ability to mobilise interstitial fluid so readily may make subcutaneous fluid therapy a viable treatment modality for shock (Parkinson, 2023) (Figure 3).
When determining the type and rate of fluid needed for fluid therapy, you should consider several species differences:
Crystalloids are the most commonly administered fluid type. In general, the crystalloid administered does not need to be iso-osmolar to the patient in exotic species, which is great news given the huge species differences. So, most commercially available crystalloids are appropriate for administration (Parkinson, 2023).
Because non-mammalian species have an excellent ability to use interstitial fluid, colloids are rarely required. In cases of severe haemorrhage, blood transfusion can be considered.
Determining body temperature is an important consideration for any exotic species presenting as an emergency. In small mammals, hypothermia has been associated with poor clinical outcomes (Di Girolamo et al., 2016; Levy et al., 2021). As reptiles are ectotherms, body temperature is correlated with ambient temperature and supplemental heat should be provided in these patients unless overheating is suspected. Core body temperature is poorly correlated with cloacal temperature in avian patients (Liles and Di Girolamo, 2023). Furthermore, cloacal temperature significantly increases with prolonged restraint in avian species (Doss and Mans, 2017), making it unreliable.
Heat support can be administered to exotic species in the same ways as canine and feline patients – with thermostatically controlled heat mats, warm air blankets, incubators and the administration of warmed fluid therapy.
Once the patient is adequately triaged and supportive care has been administered, you should think about the provision of nutritional support. Many debilitated exotic patients require syringe feeding, and fluid therapy can be incorporated into several brands of semi-elemental critical care feeding formulas that require the addition of water to administer (Figure 6).
A vast number of formulas are commercially available, and each practice will have a preference for the formulation chosen. However, it is important to ensure that hospitalised patients are provided with adequate food and water. You should also provide syringe feeding if they are not eating to prevent the recurrence of dehydration and hypovolaemia.
Any exotic patient presenting as an emergency should be immediately evaluated by the clinical team. In most cases, signs of dehydration or shock are absent, and it should be assumed that any patient with acute haemorrhage or chronic decompensated disease is likely in hypovolaemic shock. Fluid therapy with isotonic crystalloids is usually the most appropriate method for treating exotic patients with trauma and/or shock. In non-mammalian species, hypovolaemic shock can effectively be treated with subcutaneous fluid therapy. Consideration should also be given to the patient’s body temperature and the provision of adequate nutrition.
References (click to expand)