POST-HIBERNATION ANOREXIA IN CHELONIA: DIAGNOSIS AND CARE

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1 Vet Times The website for the veterinary profession POST-HIBERNATION ANOREXIA IN CHELONIA: DIAGNOSIS AND CARE Author : Mark Rowland Categories : Vets Date : February 27, 2012 Mark Rowland provides an overview of the signs associated with this condition, looking at diagnosis and investigation, as well as treatment options ANOREXIA is a common presentation for tortoises in the post-hibernation period. There are many causes of this potentially devastating condition. This article is intended to assist veterinary surgeons in the work-up, diagnosis and treatment of post-hibernation anorexia (PHA) in chelonia. Signalment The issues that may lead to PHA begin in the previous year. Firstly, it is important to establish that the tortoise presented is a species that hibernates. Attempting to hibernate a nonhibernating species could be fatal. Species commonly presented that do not hibernate include leopard, red foot ( Figure 1 ), yellow foot, Indian star and sulcata (African spurred) tortoises. This is not an exhaustive list, but many keepers of the more exotic tortoises will know not to hibernate a species that does not do so in the wild. The most common hibernating species include the spur thigh, Hermann s, marginated and Horsefield s tortoises. It is very important to ensure there were no problems with the tortoise prior to its hibernation. If there was any disease process occurring, it may be exacerbated by the hibernation, putting huge stress on the animal. If the animal was weighed prior to hibernation, this weight should be noted and compared to a post-hibernation weight. 1 / 7

2 A healthy tortoise will lose about one per cent of its bodyweight per month during hibernation. Pathophysiology There are several factors that contribute to the disease processes identified in PHA: improper preparation for hibernation. The wind-down period is a stage in the autumn during which the tortoise prepares itself for hibernation. Characteristically, tortoises will become more lethargic and abstain from food for four to six weeks (shorter for young tortoises). This allows them to empty their gastrointestinal tract. It is important during this period to ensure the tortoise is fit to hibernate and is bathed regularly to build up fluid stores that it will rely on during hibernation. If the wind-down is not carried out normally and the tortoise is not physiologically ready to hibernate, posthibernation problems are likely. Duration of hibernation. If left to their own devices, tortoises would hibernate for much longer in the UK than they would in the wild. This is because the cues to wake up (notably increasing ambient temperature) are not present in the British climate. This has tremendous implications for tortoise health. During the hibernation period, tortoises are still producing nitrogenous waste products, albeit to a lesser extent. They are using their own body water (much of it stored in the bladder) to dilute these waste products. A tortoise hibernating for three to four months will have enough body water to successfully dilute waste for this period. In the UK, tortoises frequently present having hibernated for five to six months. As a result, they can become severely dehydrated and are hyperuricaemic. In severe cases, uric acid can come out of solution as its solubility is relatively low. This will result in visceral gout and organ damage. Hibernating conditions. It is very important to ensure the tortoise has hibernated under the correct conditions. It should be safe from predator attack and have access to fresh air. Hibernating at too warm a temperature will increase its metabolic rate and, therefore, catabolism. If the tortoise is too cold, frost will cause damage to a tortoise s sight. The ideal hibernating temperature is 4 to 6 C. Immune status. Clinically healthy tortoises in the UK often have subclinical leucopaenia because of lower temperatures and ultraviolet light levels. 2 / 7

3 During hibernation, white cell production is suppressed. The average lifespan of chelonian white blood cells is three to four weeks. This means tortoises are immunocompromised at the end of the hibernation period. It can take several weeks for white cell production to increase dramatically. The net result is that in the immediate post-hibernation period, tortoises are susceptible to a large number of diseases caused by opportunistic pathogens. These animals will present with a wide range of clinical syndromes, including stomatitis, pneumonia, aural abscessation, conjunctivitis, rhinitis, skin/shell infections and septicaemia. Diagnosis The diagnosis of PHA is relatively straightforward. These tortoises present soon after they have woken and may be totally collapsed ( Figure 2 ) or bright, but simply anorexic for more than a week after waking. Subtle jaw movements are frequently noted on clinical examination of dehydrated PHA cases. An investigation into the underlying cause is always warranted as well as the treatment of any obvious pathology uncovered during a physical examination. If the tortoise has urinated, the urine should be examined for any changes in colouration. Green-stained urates can be indicative of liver disease in chelonia ( Figure 3 ). A direct wet preparation of urine may reveal the presence of a large number of motile protozoa. PHA cases are often desperately sick and require early and aggressive therapy. Initial treatment and investigation Many PHA cases require hospitalisation for investigation of the underlying cause, as well as the initiation of aggressive, supportive care. It is vital these reptiles are hospitalised within their activity temperature range (ATR). Tortoises physiology is adapted to operate at higher than UK room temperature. In practical terms, this means they should be provided with a background temperature of 25 C to 30 C, dropping to roughly 16 C at night. Ultraviolet light should be provided for 14 hours per day. This will help stimulate the tortoise s immune system as well as increase its general well-being. These animals require barrier nursing to prevent cross-infection of disease. This is especially important as hospitalised PHA cases will be immunocompromised. Blood should be drawn from the right jugular vein and submitted for biochemistry and haematology ( Figure 4 ). It is important to send the blood to a laboratory that is experienced with reptilian samples. Alternative sites include the dorsal coccygeal vein and the subcarapacial venous sinus. However, there is a more significant chance of lymph dilution with these sites that will affect any results obtained. Blood may be collected into a heparin tube for both biochemistry and haematology. In 3 / 7

4 fact, reptilian blood cells are better preserved in heparin than in EDTA. Up to one per cent of bodyweight may be taken. Most laboratories, however, are able to provide a basic reptile profile with as little as 0.3ml to 0.5ml of whole blood. Many reptilian profiles do not include urea measurement. Urea levels are an important indicator of dehydration in post-hibernation cases and should be added to the profile if possible. Fluid therapy Fluid therapy is profoundly important in cases of posthibernation anorexia. Maintenance fluid requirements for tortoises are 10ml to 30ml/ kg/day. Many PHA cases are suffering from dehydration and will require fluid replacement. Fluid deficit replacement should take place over two to four days to avoid volume overload. The upper limit for fluid replacement is roughly 40ml/kg/day. Several routes are available for fluid replacement: Intravenous/intraosseous. These routes are available for continuous rate infusion and are suited for severely dehydrated reptiles (in which other routes may be less effective). The jugular vein may be accessed for IV therapy. For IO therapy, the author prefers the gular scutes at the cranial plastron ( Figure 5 ). Epicoelomic. This route is useful for bolus administration and has the advantage of being remote from the bladder so iatrogenic bladder puncture is less likely. Injection is through the cranial inlet of the shell, laterodorsal to the head and neck, just dorsal to the plastron ( Figure 6 ). Up to 20ml may be delivered via this route. Coelomic. The site for coelomic fluid injection is the prefemoral fossa ( Figure 7 ). Care should be exercised to avoid accidental puncture of the bladder, the contents of which are nonsterile. Up to 30ml of fluids may be administered. Oral. Stomach volume is estimated at five per cent of bodyweight. This is the normal physiological route. Fluids may be given by gavage tube or a pharangostomy tube may be fitted under light anaesthesia ( Figure 8 ). The author prefers a bolus of 5mg/kg alfaxalone given intravenously to allow sufficient sedation for this procedure even in debilitated tortoises. 4 / 7

5 Bathing. It is postulated that cloacal drinking occurs in terrestrial chelonia. Daily bathing in warm water will stimulate the tortoise to void urine and may help in rehydrating mild cases of PHA. Products are available to add to the bath these contain energy precursors, probiotics and electrolytes. Normal saline is acceptable for initial rehydration. Oral rehydration formulas are also useful. Nutritional support Nutritional therapy may commence once the patient is stabilised. It is important not to introduce nutritional therapy too soon. If this occurs, the sudden release of insulin may result in profound hypokalaemia and hypophosphataemia. This phenomenon is known as refeeding syndrome and can have lifethreatening consequences in an already debilitated patient. The author prefers Critical Care for Herbivores (Oxbow) for initial and continued nutritional support in these cases. Specific conditions Hyperuricaemia/gout. As statedpreviously, rising uric acid levels may result in precipitation of urates. This will lead to visceral or articular gout. The temperomandibular joint seems to be commonly affected ( Figure 9 ). Treatment with allopurinol (20mg/kg/day orally) will decrease uric acid production and so reduce levels. Uric acid crystals will damage any organ they are deposited in and, therefore, lead to dysfunction of that organ. Rodent injuries ( Figure 10 ). These are common where tortoises do not have adequate protection while hibernating. They may be severe, possibly requiring limb amputation. Adequate stabilisation, analgesia, antibiosis and wound management are required. Stomatitis (mouth rot). Bacterial infections in the buccal cavity are common in cases of PHA. There are often large, yellow necrotic plaques of tissue on the tongue and oral mucosa ( Figure 11 ). Treatment includes culture and sensitivity of the swabbed lesions, herpesvirus PCR of oral swabs and antibiosis and analgesics as indicated, along with appropriate supportive care. Runny nose syndrome. Normal chelonian respiration should not include evidence of nasal discharge or bubbles at the nares. If this is present, appropriate antibiosis based on culture, alongside nebulisation, are 5 / 7

6 required. Herpesvirus testing is also recommended. Many ocular antibiotic drops may be instilled into the nasal cavity (such as chloramphenicol drops, ciprofloxacin drops). Pneumonia. This condition is usually diagnosed by cranio-caudal and lateral radiographs. The lungs are dorsal to the coelomic viscera and can be skylined with these views ( Figure 12 ). Nebulisation, fluid therapy and antibiosis based on culture of lung secretions are required for treatment, which should be aggressive and may be protracted. Aural abscessation. Abscesses of the ear arise as extensions of stomatitis where the infection tracks up the eustachian tube. Large swellings over the tympanic scale may be seen unilaterally or bilaterally. These abscesses require surgical debridement. A ventral window is created in the tympanic scale and the pus is removed. The pus is usually very thick and leaves a cavity after it has been removed. The wound is left open for gentle irrigation and heals by secondary intention ( Figure 13 ). Blindness. This is caused by frost damage if the tortoise is hibernated at too cool temperatures. Associated ocular lesions include hyphema, vitreal haze, lenticular opacities and retinal damage. Improvement over time may be noted. Circling may also be a clinical feature. Parasitism. Adult roundworms will overwinter inside the tortoise during the hibernation period. If the tortoise is debilitated through concurrent disease on waking, intestinal parasitism may play a role in worsening the situation. Whole worms may be passed or eggs and larvae may be visible on examination of a direct faecal wet mount ( Figure 14 ). Urine should also be examined and protozoal parasites, such as Hexamitaspecies may cause renal disease in chelonia. Septicaemia. Many bacterial diseases of chelonia may lead to a generalised infection (septicaemia). This condition is life threatening and requires aggressive therapy. Blood culture may be helpful in these cases. If left untreated, haematogenous spread of infection will occur, leading to osteomyelitis and valvular endocarditis. A septicaemic red flush is often noted on the plastron in these cases ( Figure 15 ). Summary Most PHA cases in tortoises can be managed with appropriate supportive care and fluid 6 / 7

7 Powered by TCPDF ( replacement. However, it is important to identify those cases that require more invasive or longterm care as soon as possible to exact a successful outcome. Client education is also vital to ensure any husbandry-related causes are identified and corrected. See Table 1 for the formulary. Further reading Highfield A and Lancaster A. Safer Hibernation and your Tortoise, Mitchell M and Tully T (2008). Manual of Exotic Pet Practice, Elsevier Saunders: Calvert I (2004). Nutritional Problems. In Girling S and Raiti P (eds) BSAVA Manual of Reptiles (2nd edn), BSAVA: Carpenter J (2005). Exotic Animal Formulary (3rd edn), Elsevier Saunders. 7 / 7