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Diagnostic Challenge
DIAGNOSTIC CHALLENGE
History A 5-year-old female sugar glider (Petaurus breviceps) was presented to the Louisiana State University School of Veterinary Medicine (Baton Rouge, LA USA) as an emergency for disuse and injury of the right pelvic limb. Two days prior, the owner had found the sugar glider with her pelvic limbs caught in a towel, but the pet appeared to recover without difficulty. However, early on the day of presentation, the owner found the animal with her FIGURE 1. Left lateral radiographic image of a sugar glider that preright pelvic limb caught in the cage. Since the second sented to the hospital for an injury to the right limb. incident, the sugar glider had reportedly been dragging the leg behind her, had decreased appetite and energy, and was unusually aggressive toward the owner. The animal was fed a glider-specific pelleted diet (brand unknown), oats, fruits, and vegetables; tap water was available at all times. The sugar glider had a large cage with multi-level perches and hideaways but was generally free roaming in the owner’s bedroom and, when under supervision, other parts of the house. On physical examination, the patient was bright, alert, and responsive but 7% to 10% dehydrated. The sugar glider was fairly small and in a suboptimal body condition at 52 g (body condition score, 2 of 5). Her right rear foot was swollen and erythematous, with a superficial abrasion on the distomedial aspect of the third digit. She was able to move her hindlimbs when held and had good bilateral range of motion, but seemed to have decreased withdrawal reflexes, particularly with the left leg. When ambulating, both pelvic limbs dragged behind her, with the left side more severely affected. The remainder of the examination was within normal limits. The sugar glider was hospitalized and provided with supportive care in the form of warmth, parenteral fluids (lactated Ringer solution at 100 mL/kg subcutaneously; Hospira Inc., Lake Forest, IL USA), a nonsteroidal anti-inflammatory (meloxicam, 0.15 mg/kg subcutaneously; Metacam, Boehringer Ingelheim, St Joseph, MO USA), and analgesia (butorphanol, 0.5 mg/kg intramuscularly; Fort Dodge Animal Health, Fort Dodge, IA USA). She was also offered free-choice fruits, sugar glider pellets, and water. The following morning, blood was drawn from the cranial vena cava under general anesthesia (isoflurane in oxygen). Because of the small blood volume collected, only a partial chemistry panel was possible; ␥-glutamyl transferase, total bilirubin, sodium, potassium, chloride, bicarbonate, and anion gap were not included. Abnormal findings on the plasma chemistry panel were hypocalcemia (4.1 mg/dL; reference range, 7.1-10.3 mg/dL); hypoproteinemia (4.6 g/dL; reference range, 5.5-8.3 g/dL), predominantly characterized by hypoalbuminemia (2.7 g/dL; reference range, 3.1-4.7 g/dL); and increased alkaline phosphatase level (1828 U/L; reference range, 0-215.6 U/L).1 Survey radiographs of the patient are shown in Figures 1 and 2. At this time, please evaluate the history, physical examination findings, clinical biochemistry results, and radiographic images (Figs. 1 and 2). From these preliminary diagnostics, develop a differential disease diagnosis list and plan for additional diagnostics and/or therapeutics.
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Journal of Exotic Pet Medicine 21 (2012), pp 354 –357
hypoglycemia, and generalized malnutrition. In comparison with conspecifics, the radiographs showed generalized decreased bone opacity, with loss of definition of dorsal spinous processes of the cervical and thoracic vertebrae (Fig. 3). This finding, in combination with acute hindlimb paresis, hypocalcemia, and hypoproteinemia, was highly suggestive of nutritional secondary hyperparathyroidism. An elevated alkaline phosphatase level is also consistent with active bone resorption associated with this condition. The sugar glider was treated with calcium glubionate, 150 mg/kg, orally, every 24 hours and continued supportive care. The patient was discharged the following day, with instructions for cage rest without climbing access, long-term administration of calcium glubionate, and recommendations for dietary modification, including calcium supplementation. On a recheck examination, 2 weeks later, the sugar glider appeared much improved, and there was no evidence of hindlimb paresis. DISCUSSION
Figure 2. Ventrodorsal radiographic image of a sugar glider with an injury to the right limb.
DIAGNOSIS On presentation, the initial differential disease diagnosis list included trauma, exertional myopathy, nutritional secondary hyperparathyroidism,
Nutritional secondary hyperparathyroidism, or nutritional osteodystrophy, in sugar gliders has been attributed to inadequate dietary calcium, inappropriate calcium-phosphorus ratio, and/or inadequate vitamin D in the diet. As nocturnal animals, it is thought that sugar gliders may be more dependent on absorption of dietary vitamin D3 than on dermal conversion of vitamin D2 from exposure to ultraviolet light.2 Hypocalcemia leads to elevated parathyroid hormone levels, which results in increased calcium resorption and phosphorus excretion by the renal tubules, mobilization of calcium from bone via osteolysis, and stimulation of formation of active vitamin D by the kidneys. These mechanisms increase serum
Figure 3. Same radiographic image as Figure 1 showing loss of definition of the dorsal spinous processes of the cervical and thoracic (arrows) vertebrae.
Jones and Tully/Journal of Exotic Pet Medicine 21 (2012), pp 354 –357
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calcium levels, and animals may be normocalcemic until the condition becomes severe. Nutritional secondary hyperparathyroidism is a very common condition of captive sugar gliders. Many authors recommend a homemade diet, such as that listed by Ness and Johnson-Delaney,3 because commercial glider pellets tend to lack regulation and extensive research.4 These recipes are based on what nutritional knowledge we do have on the species, and zoos will typically follow this approach. Brust,1 however, contends that homemade diets are impractical for the average owner, who tends to modify recipes as convenience, cost, or animal preference dictates; thus, the diets typically become nutritionally unbalanced. Therefore, Brust prefers a commercial pellet as the primary dietary offering. There is agreement that a portion, but not a majority, of the diet be a mixture of fresh fruits and vegetables with treats making up less than 5% of daily food intake. Vitamin and mineral supplementation is also recommended for captive sugar gliders, whether from gut-loading insects or sprinkling over the food. Overall, it is suggested that the preferred sugar glider diet contain approximately 1% calcium, 0.5% phosphorus, and 1500IU/kg vitamin D3 on a dry matter basis.1,3-5 Besides nutritional secondary hyperparathyroidism, adherence to an appropriate diet can also reduce the risk of other common conditions, such as obesity, hypoglycemia, and dental disease. Sugar gliders with nutritional secondary hyperparathyroidism commonly present with acuteonset hindlimb paresis, hypocalcemia, hypoproteinemia, and pathologic fractures (Fig. 4). There is generally a history of a nutritionally incomplete diet being fed to the animal, often one high in fruits, low in protein, and lacking in calcium supplementation. In particularly severe cases of nutritional secondary hyperparathyroidism in sugar gliders, seizures, tremors, or tetany may be observed. A complete history, physical examination, hematology, and radiographs are all recommended to confirm the diagnosis and adequately assess the patient’s condition. The primary treatment for a sugar glider diagnosed with nutritional secondary hyperparathyroidism is calcium supplementation in the form of calcium glubionate (150 mg/kg, orally, every 24 hours)3; Brust1 recommends using calcium gluconate (100 mg/kg, subcutaneously, twice a day) for the first 3 to 5 days before switching to oral supplementation. In individuals with severe central nervous system signs, such as seizures, intravenous calcium gluconate (100-150 mg/kg, slow intravenous infusion) may be indicated; however, 3 5 6
Figure 4. Ventrodorsal radiographic image of a sugar glider diagnosed with a severe case of nutritional secondary hyperparathyroidism. There are at least 17 new or previous fractures identified in this radiographic image. No abnormal behavior was detected by the owner until 5 days before presentation to the veterinary hospital.
because of the risk of arrhythmias and bradycardia, administration should only be performed when adequate cardiac monitoring is in place (e.g., electrocardiography or continuous auscultation).6 If seizure activity occurs, anticonvulsants, such as diazepam (0.5-2 mg/kg, orally, intramuscularly, intraosseously, or intravenously) should be administered.3 Supportive care in the form of fluids, warmth (approximately 80°F), appropriate diet, anti-inflammatory medication, and analgesia should also be provided as needed. In severely affected animals that remain normocalcemic, calcitonin (50-100 IU/kg, subcutaneously or intramuscularly; Miacalcin, Sandoz Ltd., Hanover, NJ USA) may be helpful in limiting additional calcium resorption from the bones by inhibiting osteoclast function.3 Miacalcin will also decrease serum calcium and phosphorus levels; therefore, it must only be given concurrently with a calcium supplement and never to hypocalcemic individuals. Although sugar gliders may not have an absolute need for ultraviolet exposure under proper hus-
Jones and Tully/Journal of Exotic Pet Medicine 21 (2012), pp 354 –357
bandry conditions, it is likely to boost serum vitamin D levels, as with reptiles; thus, exposure to an ultraviolet bulb may be helpful until normal serum calcium levels can be re-established. Once stabilized, recommended care by the owner should include continued calcium supplementation, cage rest to reduce the risk of fractures until bone strength is regained, and establishment of an appropriate diet, as described above. If fractures are present, concurrent treatment in conjunction with proper husbandry and diet is required. Given sugar gliders’ diminutive size and inclination to self-mutilate affected extremities, some authors advocate amputation over internal fixation or external splinting; sugar gliders are reported to ambulate quite well on 3 limbs.3 The patagium also presents a challenge in attempts to place splints or bandages. As with other species, adequate analgesic and anti-inflammatory medications should be provided. As with so many conditions of pet exotics, nutritional secondary hyperparathyroidism is fully preventable with appropriate nutrition and husbandry. Therefore, this case demonstrates the importance of encouraging pet owners to have their sugar glider examined whenever they acquire an animal. The initial veterinary visit not only allows for a full health assessment but also ensures that the owner is properly educated regarding the appropriate care of his or her new pet.
This case was submitted by Krista L. Jones, DVM, MS, and Thomas N. Tully Jr., DVM, MS, Dip. ABVP (Avian), Dip. ECZM (Avian), from the Department Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803. © 2012 Elsevier Inc. All rights reserved. 1557-5063/12/2104-$30.00 http://dx.doi.org/10.1053/j.jepm.2012.09.012
REFERENCES 1. Brust DM: Sugar Gliders: A Complete Veterinary Care Guide. Veterinary Interactive Publications, Inc., 2009 2. Booth RJ: General husbandry and medical care of sugar gliders, in Bonagura JD (ed): Kirk’s Current Veterinary Therapy XIII. Philadelphia, PA, W.B. Saunders, pp 1157-1163, 2000 3. Ness DN, Johnson-Delaney CA: Sugar gliders, in Quesenberry KE, Carpenter JW (eds): Ferrets, Rabbits, and Rodents—Clinical Medicine and Surgery (ed 3). St Louis, MO, Elsevier/Saunders, pp 393-410, 2012 4. Dierenfeld ES: Feeding behavior and nutrition of the sugar glider (Petaurus breviceps). Vet Clin North Am Exot Anim Pract 12:209-215, 2009 5. Brust DM, Pye GW: Sugar gliders, in Carpenter JW (ed): Exotic Animal Formulary (ed 4). St Louis, MO, Elsevier/ Saunders, pp 440-458, 2012 6. Lennox AM: Emergency and critical care procedures in sugar gliders (Petaurus breviceps), African hedgehogs (Atelerix albiventris), and prairie dogs (Cynomys spp). Vet Clin North Am Exot Anim Pract 10:533-555, 2007
Jones and Tully/Journal of Exotic Pet Medicine 21 (2012), p 354 –357
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History A 5-year-old female sugar glider (Petaurus breviceps) was presented to the Louisiana State University School of Veterinary Medicine (Baton Rouge, LA USA) as an emergency for disuse and injury of the right pelvic limb. Two days prior, the owner had found the sugar glider with her pelvic limbs caught in a towel, but the pet appeared to recover without difficulty. However, early on the day of presentation, the owner found the animal with her FIGURE 1. Left lateral radiographic image of a sugar glider that preright pelvic limb caught in the cage. Since the second sented to the hospital for an injury to the right limb. incident, the sugar glider had reportedly been dragging the leg behind her, had decreased appetite and energy, and was unusually aggressive toward the owner. The animal was fed a glider-specific pelleted diet (brand unknown), oats, fruits, and vegetables; tap water was available at all times. The sugar glider had a large cage with multi-level perches and hideaways but was generally free roaming in the owner’s bedroom and, when under supervision, other parts of the house. On physical examination, the patient was bright, alert, and responsive but 7% to 10% dehydrated. The sugar glider was fairly small and in a suboptimal body condition at 52 g (body condition score, 2 of 5). Her right rear foot was swollen and erythematous, with a superficial abrasion on the distomedial aspect of the third digit. She was able to move her hindlimbs when held and had good bilateral range of motion, but seemed to have decreased withdrawal reflexes, particularly with the left leg. When ambulating, both pelvic limbs dragged behind her, with the left side more severely affected. The remainder of the examination was within normal limits. The sugar glider was hospitalized and provided with supportive care in the form of warmth, parenteral fluids (lactated Ringer solution at 100 mL/kg subcutaneously; Hospira Inc., Lake Forest, IL USA), a nonsteroidal anti-inflammatory (meloxicam, 0.15 mg/kg subcutaneously; Metacam, Boehringer Ingelheim, St Joseph, MO USA), and analgesia (butorphanol, 0.5 mg/kg intramuscularly; Fort Dodge Animal Health, Fort Dodge, IA USA). She was also offered free-choice fruits, sugar glider pellets, and water. The following morning, blood was drawn from the cranial vena cava under general anesthesia (isoflurane in oxygen). Because of the small blood volume collected, only a partial chemistry panel was possible; ␥-glutamyl transferase, total bilirubin, sodium, potassium, chloride, bicarbonate, and anion gap were not included. Abnormal findings on the plasma chemistry panel were hypocalcemia (4.1 mg/dL; reference range, 7.1-10.3 mg/dL); hypoproteinemia (4.6 g/dL; reference range, 5.5-8.3 g/dL), predominantly characterized by hypoalbuminemia (2.7 g/dL; reference range, 3.1-4.7 g/dL); and increased alkaline phosphatase level (1828 U/L; reference range, 0-215.6 U/L).1 Survey radiographs of the patient are shown in Figures 1 and 2. At this time, please evaluate the history, physical examination findings, clinical biochemistry results, and radiographic images (Figs. 1 and 2). From these preliminary diagnostics, develop a differential disease diagnosis list and plan for additional diagnostics and/or therapeutics.
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Journal of Exotic Pet Medicine 21 (2012), pp 354 –357
hypoglycemia, and generalized malnutrition. In comparison with conspecifics, the radiographs showed generalized decreased bone opacity, with loss of definition of dorsal spinous processes of the cervical and thoracic vertebrae (Fig. 3). This finding, in combination with acute hindlimb paresis, hypocalcemia, and hypoproteinemia, was highly suggestive of nutritional secondary hyperparathyroidism. An elevated alkaline phosphatase level is also consistent with active bone resorption associated with this condition. The sugar glider was treated with calcium glubionate, 150 mg/kg, orally, every 24 hours and continued supportive care. The patient was discharged the following day, with instructions for cage rest without climbing access, long-term administration of calcium glubionate, and recommendations for dietary modification, including calcium supplementation. On a recheck examination, 2 weeks later, the sugar glider appeared much improved, and there was no evidence of hindlimb paresis. DISCUSSION
Figure 2. Ventrodorsal radiographic image of a sugar glider with an injury to the right limb.
DIAGNOSIS On presentation, the initial differential disease diagnosis list included trauma, exertional myopathy, nutritional secondary hyperparathyroidism,
Nutritional secondary hyperparathyroidism, or nutritional osteodystrophy, in sugar gliders has been attributed to inadequate dietary calcium, inappropriate calcium-phosphorus ratio, and/or inadequate vitamin D in the diet. As nocturnal animals, it is thought that sugar gliders may be more dependent on absorption of dietary vitamin D3 than on dermal conversion of vitamin D2 from exposure to ultraviolet light.2 Hypocalcemia leads to elevated parathyroid hormone levels, which results in increased calcium resorption and phosphorus excretion by the renal tubules, mobilization of calcium from bone via osteolysis, and stimulation of formation of active vitamin D by the kidneys. These mechanisms increase serum
Figure 3. Same radiographic image as Figure 1 showing loss of definition of the dorsal spinous processes of the cervical and thoracic (arrows) vertebrae.
Jones and Tully/Journal of Exotic Pet Medicine 21 (2012), pp 354 –357
3 5 5
calcium levels, and animals may be normocalcemic until the condition becomes severe. Nutritional secondary hyperparathyroidism is a very common condition of captive sugar gliders. Many authors recommend a homemade diet, such as that listed by Ness and Johnson-Delaney,3 because commercial glider pellets tend to lack regulation and extensive research.4 These recipes are based on what nutritional knowledge we do have on the species, and zoos will typically follow this approach. Brust,1 however, contends that homemade diets are impractical for the average owner, who tends to modify recipes as convenience, cost, or animal preference dictates; thus, the diets typically become nutritionally unbalanced. Therefore, Brust prefers a commercial pellet as the primary dietary offering. There is agreement that a portion, but not a majority, of the diet be a mixture of fresh fruits and vegetables with treats making up less than 5% of daily food intake. Vitamin and mineral supplementation is also recommended for captive sugar gliders, whether from gut-loading insects or sprinkling over the food. Overall, it is suggested that the preferred sugar glider diet contain approximately 1% calcium, 0.5% phosphorus, and 1500IU/kg vitamin D3 on a dry matter basis.1,3-5 Besides nutritional secondary hyperparathyroidism, adherence to an appropriate diet can also reduce the risk of other common conditions, such as obesity, hypoglycemia, and dental disease. Sugar gliders with nutritional secondary hyperparathyroidism commonly present with acuteonset hindlimb paresis, hypocalcemia, hypoproteinemia, and pathologic fractures (Fig. 4). There is generally a history of a nutritionally incomplete diet being fed to the animal, often one high in fruits, low in protein, and lacking in calcium supplementation. In particularly severe cases of nutritional secondary hyperparathyroidism in sugar gliders, seizures, tremors, or tetany may be observed. A complete history, physical examination, hematology, and radiographs are all recommended to confirm the diagnosis and adequately assess the patient’s condition. The primary treatment for a sugar glider diagnosed with nutritional secondary hyperparathyroidism is calcium supplementation in the form of calcium glubionate (150 mg/kg, orally, every 24 hours)3; Brust1 recommends using calcium gluconate (100 mg/kg, subcutaneously, twice a day) for the first 3 to 5 days before switching to oral supplementation. In individuals with severe central nervous system signs, such as seizures, intravenous calcium gluconate (100-150 mg/kg, slow intravenous infusion) may be indicated; however, 3 5 6
Figure 4. Ventrodorsal radiographic image of a sugar glider diagnosed with a severe case of nutritional secondary hyperparathyroidism. There are at least 17 new or previous fractures identified in this radiographic image. No abnormal behavior was detected by the owner until 5 days before presentation to the veterinary hospital.
because of the risk of arrhythmias and bradycardia, administration should only be performed when adequate cardiac monitoring is in place (e.g., electrocardiography or continuous auscultation).6 If seizure activity occurs, anticonvulsants, such as diazepam (0.5-2 mg/kg, orally, intramuscularly, intraosseously, or intravenously) should be administered.3 Supportive care in the form of fluids, warmth (approximately 80°F), appropriate diet, anti-inflammatory medication, and analgesia should also be provided as needed. In severely affected animals that remain normocalcemic, calcitonin (50-100 IU/kg, subcutaneously or intramuscularly; Miacalcin, Sandoz Ltd., Hanover, NJ USA) may be helpful in limiting additional calcium resorption from the bones by inhibiting osteoclast function.3 Miacalcin will also decrease serum calcium and phosphorus levels; therefore, it must only be given concurrently with a calcium supplement and never to hypocalcemic individuals. Although sugar gliders may not have an absolute need for ultraviolet exposure under proper hus-
Jones and Tully/Journal of Exotic Pet Medicine 21 (2012), pp 354 –357
bandry conditions, it is likely to boost serum vitamin D levels, as with reptiles; thus, exposure to an ultraviolet bulb may be helpful until normal serum calcium levels can be re-established. Once stabilized, recommended care by the owner should include continued calcium supplementation, cage rest to reduce the risk of fractures until bone strength is regained, and establishment of an appropriate diet, as described above. If fractures are present, concurrent treatment in conjunction with proper husbandry and diet is required. Given sugar gliders’ diminutive size and inclination to self-mutilate affected extremities, some authors advocate amputation over internal fixation or external splinting; sugar gliders are reported to ambulate quite well on 3 limbs.3 The patagium also presents a challenge in attempts to place splints or bandages. As with other species, adequate analgesic and anti-inflammatory medications should be provided. As with so many conditions of pet exotics, nutritional secondary hyperparathyroidism is fully preventable with appropriate nutrition and husbandry. Therefore, this case demonstrates the importance of encouraging pet owners to have their sugar glider examined whenever they acquire an animal. The initial veterinary visit not only allows for a full health assessment but also ensures that the owner is properly educated regarding the appropriate care of his or her new pet.
This case was submitted by Krista L. Jones, DVM, MS, and Thomas N. Tully Jr., DVM, MS, Dip. ABVP (Avian), Dip. ECZM (Avian), from the Department Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803. © 2012 Elsevier Inc. All rights reserved. 1557-5063/12/2104-$30.00 http://dx.doi.org/10.1053/j.jepm.2012.09.012
REFERENCES 1. Brust DM: Sugar Gliders: A Complete Veterinary Care Guide. Veterinary Interactive Publications, Inc., 2009 2. Booth RJ: General husbandry and medical care of sugar gliders, in Bonagura JD (ed): Kirk’s Current Veterinary Therapy XIII. Philadelphia, PA, W.B. Saunders, pp 1157-1163, 2000 3. Ness DN, Johnson-Delaney CA: Sugar gliders, in Quesenberry KE, Carpenter JW (eds): Ferrets, Rabbits, and Rodents—Clinical Medicine and Surgery (ed 3). St Louis, MO, Elsevier/Saunders, pp 393-410, 2012 4. Dierenfeld ES: Feeding behavior and nutrition of the sugar glider (Petaurus breviceps). Vet Clin North Am Exot Anim Pract 12:209-215, 2009 5. Brust DM, Pye GW: Sugar gliders, in Carpenter JW (ed): Exotic Animal Formulary (ed 4). St Louis, MO, Elsevier/ Saunders, pp 440-458, 2012 6. Lennox AM: Emergency and critical care procedures in sugar gliders (Petaurus breviceps), African hedgehogs (Atelerix albiventris), and prairie dogs (Cynomys spp). Vet Clin North Am Exot Anim Pract 10:533-555, 2007
Jones and Tully/Journal of Exotic Pet Medicine 21 (2012), p 354 –357
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