Dehydration is a serious condition in Leopard geckos. Applying the correct principles, fluid treatment can be life-saving.
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Fluid treatment, also known as fluid therapy, fluid replacement or fluid resuscitation, is the medical practice of replacing body fluids that have been lost. Factors such as timing, type and quantity of fluid and route of administration need to be considered when treating fluid loss in Leopard geckos.
Water is the single most important medium for sustaining life(47). Studies have shown that the percentage of total body water (TBW) is higher in reptiles (up to 75%) than in mammalian species (60-70%)(48). TBW is distributed between intracellular fluid (ICF) and extracellular fluid (ECF) compartments. The ICF makes up 66% of total body water, while the ECF compartment makes up 33%. Water moves freely throughout most parts of the body(48).
Over the last couple of decades, there has been a lot of advances made in our understanding of fluid treatment of Leopard geckos and other reptiles. As with humans, and for example dogs and cats, many Leopard gecko lives have been saved by correcting dehydration under life-threatening situations. Although there are some ways Leopard gecko owners can attempt fluid treatment at home, specialised veterinary products, accessories and knowledge will often be required in these situations.
Leopard geckos can lose body fluids in cases such as trauma or bleeding (blood is also a fluid) or during dehydration. In most cases, dehydration is caused by chronic (long term) inability to sustain or replace fluids. Blood loss is more often acute (over a short period of time). Fluid treatment protocols will be different for acute and chronic fluid loss. Chronic blood loss can also be as a result of decreased red blood cell production.
Before fluid treatment is initiated, it is essential to identify the cause of fluid loss. Hydration and blood loss needs to be addressed before feeding is commenced(38) — even if it takes days. Normovolemia (normal levels of fluid) also needs to be established before other organ system abnormalities are addressed. Various treatment protocols will be more efficient in properly hydrated patients. Fluid treatment principles in Leopard geckos and other reptiles are similar to that of mammalian patients.
Quick notes on shock treatment
Hypovolemic and septic shock, severe blood loss, and/or severe acid-base disturbances will require fluid resuscitation(42) (shock treatment). Note that, unlike in mammals, reptiles are able to maintain hemodynamic stability even in the case of substantial blood loss. This is because of a rapid shift of interstitial fluid into the vascular space(42).
In order to assess clinical signs better, admitted patients can be transferred to an enclosure/incubator with a temperature set to the middle range between 25–30 ºC / 77–86 ºF(23). Allow at least 30 minutes for the patient to be warmed up. During this time, the same incubator can be used to pre-warm the resuscitation fluids.
In a normothermic environment, clinical signs consistent with needing shock treatment include(42):
- Hypothermia (especially appendages)
- Prolonged capillary refill time
- Pale mucous membrane colour
- Tachycardia or bradycardia
For shock treatment, crystalloids in combination with colloids are recommended. Isotonic crystalloids (e.g. 0.9% physiologic saline, Plasma-Lyte A, Normosol-R and Lactated Ringers solution) can be given at a rate of 5-10 ml/kg followed by 3-5 ml/kg of a colloid solution (e.g. 10% HAES-steril). Each of them is given interosseus (see more below) as a slow bolus over 5-10 minutes(42).
Dehydration is the common term used when the body is depleted of fluids. In other words, when the total fluid loss exceeds fluid intake, a fluid deficit occurs. In most cases, dehydration is caused by chronic (long term) inability to sustain or replace fluids.
Each day our bodies, including those of Leopard geckos, lose a small percentage of fluids. Fluids are naturally lost through normal processes such as breathing, evaporation from the skin, urination, defaecation, etc. These losses are replaced by eating food and drinking water (food also contains water).
Common reasons for dehydration in Leopard geckos include:
- diseases (through, for example, refusal to eat/drink, diarrhoea or regurgitation/bringing up food),
- physical conditions (making it difficult or impossible to eat and/or drink), and
- incorrect husbandry (e.g. where the temperature, humidity and/or the supply of food and water is incorrect)
Note that during the skin shedding process, Leopard geckos become very susceptible to dehydration(38).
Exact hydration in Leopard geckos can be tricky to estimate (especially before it is quite advanced), but clinicians often classify dehydration as normal to mild (<5%), moderate, (5-<10%) or severe (≥10-15%). This percentage is relative to the body weight (BW) — a 50 gram, moderately (e.g. 5%) dehydrated Leopard gecko has lost about 2.5ml of fluids.
Signs of dehydration in Leopard gecko include:
- flexible (nonrigid) eyelids
- sunken eyes
- dry/sticky/tacky mucous membranes (lining of the mouth)
- the tenaciousness/dry ropiness of saliva
- loss of skin turgor (elasticity) — especially seen on the sides of the body(42)
Moderate to severe dehydration can be assumed in cases where weight loss occurred over a prolonged period of time(38). Additionally, blood tests such as packed cell volume (PCV), total proteins (TP), blood urinary nitrogen (BUN) and plasma sodium and chloride are also evaluated(38).
Types of fluids
In medicine, replacement fluids can be divided into crystalloids and colloids. Knowing whether fluid losses are mainly intracellularly (i.e. from inside the body’s cells), interstitially (i.e. around the cells, but extra-vascular) or intra-vascular (i.e. from the blood vessels), one can decide whether to use a colloid or crystalloid to replace lost fluids. Crystalloids are fluids that contain small mineral-salts and are mainly used for dehydration, whereas colloids contain larger molecules, and is more favoured in the case of blood loss and/or hypoalbuminaemia. A combination of the two are used in cases of shock (see earlier).
Crystalloids are further divided into isotonic, hypotonic and hypertonic. Isotonic crystalloids are those with an osmolarity similar to blood. They are the most frequently used treatment fluid in Leopard geckos and other animal species. Commercially available isotonic crystalloids include 0.9% physiologic saline, Plasma-Lyte A, Normosol-R and Lactated Ringers solution. 5% dextrose is considered an isotonic and hypotonic solution.
Some clinicians report that isotonic crystalloids should be used with caution in the case of hypotonic fluid losses (e.g. diabetes insipidus, hyperventilation, diarrhoea, end-stage renal failure, etc.). In these cases (i.e. in the case of hypernatraemia), a hypotonic fluid solution (e.g. physiological water mixed with glucose) should be used(48). Other clinicians do not encourage crystalloid dilution and claim that it is of limited clinical use(38). A 50:50 mixture with 5% glucose in physiological water can be used in hypoglycaemic Leopard gecko patients (Glc ~< 4.3 mmol/l)(39).
Colloid treatment is given in combination with crystalloid treatment and is indicated in cases of severe blood loss, hypoalbuminemia (very low proteins in the blood), increased capillary permeability (e.g. shock), hypovolemic perfusion deficits or conditions with less tolerance for large volume infusion (e.g. brain and pulmonary disease and cardiac insufficiency)(38). They can either be natural (e.g. whole Leopard gecko blood, plasma, concentrated albumin and polymerized bovine haemoglobin) or synthetic (e.g. hydroxyethyl starches — hetastarch/ HAES–steril — and dextrans)(38). The safety and efficacy of heterologous blood transfusions (blood transfusions from different species) have not been reported(38).
Leopard geckos with diarrhoea and regurgitation can be treated with isotonic crystalloids(38).
Routs for administrating fluids
Although various fluid replacement methods have been described for reptiles(37)(38)(42), in Leopard geckos, they are limited to assist drinking, orogastric tube–feeding and subcutaneous (SC), intracoelomic (ICo) and intraosseous (IO) fluid administration. As of yet, the author was unable to find any authoritative literature supporting the, often reported, fact that lizards (and other non–aquatic reptiles) can absorb water through their skins. There is also no support for, the so-called, ‘cloacal-drinking’(38).
Assist drinking and orogastric tube–feeding relies on a functional gastrointestinal tract. Subcutaneous fluid injections are effective in lizards with mild (<5%) dehydration. This route is also fairly safe and easy to perform and can be used to deliver large quantities of fluids(37). It is usually given as a bolus under the skin over the lateral thoracic area (over the upper ribs) using a high gauge (i.e. thin) needle and syringe.
Many Leopard geckos will drink voluntarily when placed into a shallow water bath for 10 mins.(38). The water temperature needs to be similar to that of the enclosure (i.e. 25–30 ºC / 77–86 ºF(23), use a thermometer) and the soaking container needs to be deep enough to prevent escape.
Fluid administration given by orogastric tube-feeding has limited use in the case of intestinal obstructions and should rather be reserved for when feeding commences.
In moderate to severe cases of dehydration (>8%), non-irritating ICo fluids or IO fluids can be given(37)(38). In lizards, the coelomic cavity (similar to the abdominal cavity in humans) is the area that contains the gastrointestinal tract and other organs. The large serosal surface area of the viscera (organs) and the coelomic membrane of lizards allow for rapid fluid absorption. Fluids can be injected as a bolus by advancing a short, high gauge, over-the-needle catheter (e.g. yellow or blue Jelco I.V. catheter) into this space while the patient is in dorsal recumbency. The catheter is placed pointing cranially (towards the head), semi-parallel with skin, entering at the caudal third of the abdomen. To avoid accidental puncture of the ventral abdominal vein the midline should be avoided or a paramedian approach can be followed. ICo fluid administration is considered less favourable by some clinicians do the to risk of entering the lungs, urinary bladder and gastrointestinal tract(42).
Intraosseous fluids (fluids given into the bone canal) can be administered to patients weighing as little as 50 grams (e.g. an average-sized adult Leopard gecko). IO fluid administration is indicated in severe dehydration, shock treatment, acute volume depletion or those that need colloids or glucose(38).
Although their placement is more secure, it might require heavy sedation, local anaesthesia or general anaesthesia in combination with premedication(42) in patients that are not treated for shock. IO fluids need to be administered through constant rate infusion (CRI, e.g. infusion pumps or syringe drivers), or as a slow bolus (over 5-10 minutes) in the case of shock treatment. The preferred site in Leopard geckos is the medial tibial crest (shin bone), but the distal femur (thigh bone) can also be used.
An appropriately sized spinal needle is preferred, but a 23-27 G hypodermic needle can also be used. Its length should be about a third to half the length of the bone used. To prevent entering the joint capsule, the needle is inserted at the cranial medial aspect of the tibial plateau after which it is directed along the long axis of the bone. Steady pressure will be required until the cortex is penetrated. When placed properly there will no exits sites and the leg should be able to move unrestricted (i.e. the joint capsule wasn’t penetrated). The needle should be secured using tape. Bone marrow aspiration, saline injections and radiographs can confirm correct placement(42).
IO catheter placements are contraindicated in cases of sepsis and nutritional secondary hyperparathyroidism (calcium deficiency, metabolic bone disease, MBD)(42).
The volume of fluid that needs to be given is calculated as maintenance fluids, and in the case of dehydration, vomition and diarrhoea, plus replacement fluids(38)(42) (aka deficit fluids). The replacement fluids need to be given over a period of 2 to 4 days(38)(42). The maintenance fluid requirement for reptiles are calculated as either ~10-30 ml/kg/day(23)(37)(42) or 2.5-3.5% of BW per day(40). Replacement fluids (that needs to be given over 48-96 hours) are calculated as(42):
hydration deficit (percentage decimal) x body weight (kg) x 1000 ml
A 50-gram adult Leopard gecko that is 10% dehydrated will need about 1 ml of maintenance fluids per day and an additional 5 ml replacement fluids over 2-4 days. This means the daily requirements will be about 2 ml for the first 4 days.
When CRI is not available or impractical, calculated daily requirements should be divided over 2 or 3 evenly spaced boluses(40).
Fluid treatment can be life-saving to dehydrated Leopard geckos. Various factors, such as timing, type and quantity of fluid and route of administration need to be considered. The principles for treating Leopard geckos with fluids are similar to mammals. This article also outlined shock treatment and dehydration.
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