Acute renal failure and anuria associated with vitamin D intoxication in two alpaca (Vicugna pacos) cria.

Vitamin D deficiency is the leading cause of rickets in growing llamas and alpacas in North America, New Zealand, and Australia.1–3 Prophylactic treatment with vitamin D supplements is a common husbandry practice in North America. This case report describes the clinical course, diagnostics, and pathological findings in 2 alpaca cria (Vicugna pacos), presenting at 18 days and 8 days of age, with presumptive vitamin D intoxication. Both cria developed tissue mineralization and acute renal failure after administration of excessive doses of vitamin D. Presentation of camelids with a history of vitamin D administration associated with hypercalcemia, hyperphosphatemia, and renal dysfunction strongly suggests vitamin D intoxication. Early recognition of these signs can improve clinical outcomes. A 2-day-old, 7 kg, male alpaca presented to the Ohio State University Veterinary Teaching Hospital (OSUVTH) for suspected septicemia associated with anorexia, lethargy, and potential failure of transfer of passive immunity. The cria was born unassisted, but birth was observed by the owner. The owner indicated that the dam did not have sufficient mammary secretions (colostrum) at birth to provide for the cria. Nine days after admission and successful treatment with parenteral fluids, ceftiofur (Naxcel)a and IV administered plasma (20 mL/kg body weight), the now-healthy cria and his dam were released to the owner. At home the cria was supplemented with goat's milk by nipple bottle every 2 hours to approximate 15% of body weight/d. In addition, the owner added 4.6 g of powdered goat colostrum supplement (Kaeco Colostrum Powder)b to each feeding for 7 days. This supplement contained not <2,750 IU of vitamin D3 per dose. The cria was fed every 2 hours for 12 doses/d over 7 days yielding a total cumulative dose of vitamin D3 of 231,000 IU (26,250 IU/kg or 3,750 IU/kg/d). The cria was readmitted to the Veterinary Teaching Hospital at 18 days of age for generalized weakness, anorexia, and depression. The cria remained able to stand, hold his head and neck up, and walk. The heart rate was 140 beats/min (reference range, 60–90 beats/min), the respiratory rate was 28 breaths/min (reference range, 10–30 breaths/min), the body temperature was 37.6 °C (reference range, 37.5–38.9 °C), and the cria weighed 8.8 kg.4 Thoracic auscultation was unremarkable. A CBC revealed a PCV of 36% (range 24–35%) and white blood cell count of 32.3 × 109/L (range 5.2–15.7 × 109/L), characterized by a mature neutrophilia (28.4 × 109/L; range 2.1–9.5 × 109/L) and monocytosis (1.9 × 109/L; range 0–0.6 × 109/L). The serum biochemical profile demonstrated azotemia (serum urea nitrogen [SUN] 48.5 mmol/L; range 1.48–24.4 mmol/L; creatinine 557 μmol/L; range 115–239 μmol/L), hyperphosphatemia (4.5 mmol/L; range 0.8–2.8 mmol/L), hypercalcemia (3.5 mmol/L; range 2.0–2.6 mmol/L), and hyperkalemia (9.4 mmol/L; range 3.6–6.5 mmol/L). The cria was hypoproteinemic (30 g/L; range 53–76 g/L) with hypoalbuminemia (16 g/L; range 26–47 g/L) and hypoglobulinemia (14 g/L; range 27–29 g/L). The serum cortisol concentration (215 nmol/L) at the time of admission was increased compared with other hospitalized alpacas (range 0–27.59 nmol/L).5 Ultrasonographic examination of each kidney demonstrated normal architecture and echodensity with increased echogenicity of the wall of the 3rd compartment (C3). Ultrasonographic imaging of the urinary bladder revealed it was small and contained minimal urine. Thoracic radiographs revealed normal cardiopulmonary structures, while abdominal radiographs confirmed gastric wall mineralization of the caudal and ventral margins of the 3rd gastric compartment (Fig 1). Abdominal radiographs of case 1, caudal and ventral margins of the 3rd gastric compartment with mineral dense appearance, consistent with gastric mineral accumulation or gastric wall mineralization (white arrows). Initial therapy included fluids (0.45% saline with 2.5% dextrose IV) at a rate of 40 mL/h by constant rate infusion and ceftiofur sodium (20 mg IV q24h). A 20 mL bolus of 50% dextrose IV and 5 U of regular insulinc SC were given in an effort to reduce serum potassium concentration. After rehydration (approximately 6 hours from start of fluid therapy) urine production was not evident and furosemided was administered in escalating doses every 30 minutes for 2 hours (1.1–4.4 mg/kg) in an effort to reverse anuria. Seven hours after initiating fluid therapy and diuresis, the bladder had an ultrasongraphic diameter of 1.7 cm and no urination had been observed since admission. SUN (59 mmol/L) and creatinine (663 μmol/L) continued to be abnormal after 10 hours of therapy. Phosphorus (4.5 mmol/L), total calcium (3.3 mmol/L), and potassium (9.2 mmol/L) were nearly unchanged. At this time the cria's condition began deteriorating and the owner elected euthanasia. At necropsy, the cortex and medullary regions of both kidneys possessed miliary, gritty, white foci. The outer medulla of both kidneys had a 2 mm thick gritty white band of discoloration and the cortex of both kidneys had miliary gritty white foci (Fig 2). Additionally, the endothelial surface of the ascending aorta had a 1 × 3 cm gritty white plaque. The urinary bladder was small, contracted and contained <1 mL of clear yellow urine. Right kidney from case 1. Sagittal section of the kidney demonstrating mineralization of the renal medulla consistent with metastatic calcification (arrow). Areas of hyperemia surround the tissue mineralization in the renal medulla extending into the renal papilla where gritty mineralized tissue is evident (*). Histopathology of the kidneys revealed marked multifocal interstitial, tubular, and widespread glomerular mineralization with tubular nephrosis (Fig 3). Microscopically, widespread mineralization of the renal interstitium and the renal tubular and glomerular basement membranes was observed (Fig 3). Tubular necrosis with regeneration and luminal accumulation of proteinaceous material was observed in both mineralized and nonmineralized tubules. Although not detected grossly, moderate multifocal mineralization of the gastric mucosa of the 3rd compartment was observed microscopically (Fig 4). Histopathologic evidence of renal lesions present in the outer cortices, cortico-medullary junction and renal pelvis of 2 Alpaca cria described in this case using hematoxylin and eosin and Von Kossa stain for calcium salts. As highlighted by Von Kossa (calcium salts) stain, mineralization of the kidney was marked and widespread in both cases. Glomerular mineralization (*) was extensive in the outer cortex (Outer cortex) of both cases but was only associated with overt disruption of the glomerular tuft in case 2. Interstitial mineralization was most severe in the renal pelvis (pelvis) in case 1 and at the corticomedullary (CM junction) junction in case 2. Tubular basement membranes were extensively mineralized in both cases. Acute tubular necrosis (highlighted in the boxed area) with infrequent tubular regeneration (not shown) was a prominent feature in case 1 but was only occasionally observed in case 2. In both cases, mineralization of the kidney was associated with marked tubular proteinosis (arrow). Bar = 100 μm. In addition to the kidney, mineralization was observed in multiple other organs. Mineralization of C3 mucosal basement membranes (arrow) in case 1 was mild and not associated with other microscopic lesions at this site. Mineralization of the pulmonary interstitium in case 2 was marked, widespread and associated with edema and alveolar histiocytosis. Mineralization of the liver in case 2 was multifocal, marked and associated with disruption of hepatic parenchyma, hepatocellular necrosis, hemorrhage, and influx of mononuclear cells. Bar = 100 μm. Serum and kidney tissues adjacent to those taken for histopathologic evaluation were submitted for vitamin D analysis.e The 25-OH-vitamin D3 level in the serum was 663 nmol/L (normal range for alpacas 50–200 nmol/L); and kidney tissue concentration was 282.0 nmol/L (normal range 2–11 nmol/L; > 85 nmol/L suggests intoxication). An 8-day-old, male, Suri alpaca cria presented to OSUVTH for anorexia and lethargy. The owners administered 100,000 IU of vitamin D (ADE paste) PO once daily for the 1st 5 days of life for a total cumulative dose of 500,000 IU (65,909 IU/kg; 12,987 IU/kg/d for 1st 5 days of life). After the 5th day the cria was presented to the referring veterinarian for anorexia and was treated with camelid plasma IV, 7,500 IU of vitamin D3 (ADE injectable, SC) and ceftiofur (25 mg SC q12h) and gentamicin (20 mg SC q24h). Four days later the cria had not improved and became progressively more lethargic with severe epiphora, chemosis, and anuria. A biochemical profile taken by the referring veterinarian revealed a total serum calcium of 3.99 mmol/L and ionized calcium of 1.68 mmol/L. This cria was lethargic on presentation. The heart rate was 150 beats/min, the respiratory rate was 66 breaths/min, and the body temperature was 38.3°C. The cria weighed 7.7 kg. Thoracic auscultation was unremarkable. The conjunctiva were swollen and there was bilateral epiphora. The CBC revealed a PCV of 29% and white blood cell count of 15.6 × 109/L characterized by mild mature neutrophilia (14.4 × 109/L; range 2.1–9.5 × 109/L), lymphopenia (0.6 × 109/L; range 0.9–4.4 × 109/L). The serum biochemical profile revealed azotemia (SUN 85.7 mmol/L, creatinine 548 μmol/L), hyperphosphatemia (3.3 mmol/L), hypercalcemia (3.8 mmol/L), and hypoproteinemia (42 g/L) with mild hypoalbuminemia (24 g/L) and hypoglobulinemia (18 g/L). The serum cortisol (60.7 nmol/L) was also increased. Vitamin D intoxication was suspected based upon the history of supplementation and the hypercalcemia, hyperphosphatemia, azotemia, and anuria. Transabdominal ultrasonography and thoracic and abdominal radiography were performed revealing limited urine production (urinary bladder < 1.5 cm) and a thin mineral opaque rim outlining the subcapsular cortex of both kidneys. Initial therapy included treatment with fluids (Ringer's with 1% dextrose and 10 mmol KCl/L IV) at a rate of 2 mL/kg/h and ceftiofur sodium (2 mg/kg IV q12h). A Tenckoff peritoneal dialysis catheterf was placed into the abdominal cavity to perform peritoneal dialysis. Dialysis with 60 mL (8 mL/kg body weight) of warmed Dianeal PD-2 peritoneal dialysis solutiong with 1% dextrose was initiated by intraperitoneal instillation every 45 minutes. Before each infusion, dialysis fluid from the previous infusion was aspirated from the abdomen. Dialysis and administration of fluids continued for 3 days. Treatment was monitored with clinical assessment, periodic evaluation of SUN, creatinine, calcium, phosphorous, and potassium levels and ultrasonographic estimation of urine volume within the bladder. The amount of fluid recovered from the abdomen averaged 90% of the volume previously infused. After 5 hours of treatment the SUN (121 mmol/L) and creatinine (619 μmol/L) had increased. Therefore, the volume of dialysis fluid infused was increased to 16 mL/kg body weight every 45 minutes. After 17 hours of dialysis, serum concentrations of urea nitrogen (92 mmol/L) and creatinine (707 μmol/L) remained elevated; thus, the amount of dialysis fluid was increased to 24 mL/kg/mL every 45 minutes. Clinically, the cria remained lethargic and anorexic. In spite of continued fluid administration (IV and peritoneal dialysis) for 3 days, the SUN (66 mmol/L) and creatinine (998 μmol/L) remained essentially unchanged. However, serum total calcium decreased to 2.7 mmol/L. Throughout the entire course of treatment urine production was absent and the bladder remained small and devoid of hypoechoic fluid on ultrasonographic examination. The cria became unable to rise, did not nurse, and became dyspneic after 3 days of treatment, and the owner elected euthanasia. At necropsy, the gross appearance of the deep inner cortex of both kidneys was characterized by fine, radiating pale streaks. This pale region was adjacent to a region of outer medulla that was discolored dark red. The urinary bladder was empty. On histopathologic evaluation of the kidney, there was marked, diffuse glomerular mineralization with tubular necrosis and abundant accumulation of proteinaceous material within tubular lumina in sections from both kidneys (Fig 3). No normal glomeruli were present in histologic sections of the kidneys; all glomeruli were mineralized with effacement of the normal architecture of the glomerular tuft. Although not detected grossly, peripheral alveolar mineralization, alveolar histiocytosis, and marked edema were evident in the lung (Fig 4). In liver sections there was hepatocellular necrosis with multifocal mineralization (Fig 4). Serum and kidney samples revealed serum 25-OH-vitamin D3 of 602 nmol/L and kidney tissue 25-(OH)-vitamin D3 concentration of 350 nmol/L.e These cases occurred where it is a common practice to provide supplemental vitamin D to camelids during periods of reduced sunlight in North America; however, the appropriate dosage, dosage interval, and product formulations of vitamin D are often not clearly understood by camelid owners. Both cases described in this report were examined for depression, lethargy, and anorexia and were found to have acute, anuric renal failure. Azotemia, hyperphosphatemia, and hypercalcemia were present in both crias, and one had hyperkalemia. Since both cria presented with anuria and did not respond to treatment we were unable to obtain urine for determination of renal concentrating ability. Cria #1 (18 days of age) had a mature neutrophilia and monocytosis with normal lymphocyte count, whereas Cria #2 (2 days of age) had a mild neutrophilia and lymphopenia. These findings were suggestive of a stress response, which was supported by the elevated serum cortisol in both animals.5 Other possible explanations for leukocytosis, mature neutrophilia could potentially include Gram-positive bacterial sepsis, inflammatory response to tissue mineralization, renal lesions, or both.6 Both cria presented with low normal serum albumin, which decreased further after treatment was initiated. Although both cria produced minimal urine during hospitalization, we speculate that urine produced in the early stages of the disease before admission might have contained increased protein (proteinuria) which could contribute in part to decreased plasma albumin concentration. Further, after anuria developed, fluid retention could have further reduced serum albumin concentration by dilution. In case #2, the loss of serum proteins into the dialysate may also have been a contributing factor. We did not measure protein concentration in the dialysate to explain this laboratory abnormality. In both cria, hyperphosphatemia, hypercalcemia, and azotemia were suggestive of vitamin D intoxication.7 The preliminary clinical diagnosis of vitamin D intoxication was supported by the historical information and increased serum concentrations of calcium and phosphorus with apparent, acute intrinsic renal failure that did not respond to fluid therapy. The radiographic and ultrasound examinations also proved supportive of vitamin D intoxication through detection of tissue mineralization. These observations were later confirmed at postmortem examination as widespread soft tissue mineralization, grossly and microscopically. Increased vitamin D concentrations in serum and kidney tissue confirmed the diagnosis of vitamin D toxicosis in both cases. Studies performed in alpacas suggest that single parenteral doses of vitamin D (1,000–2,000 IU/kg body weight) provide adequate amounts of vitamin D to crias for up to 7–11 weeks.3 These authors recommend administering a single dose of vitamin D to South American camelids of 1,000–2,000 IU/kg bodyweight in late autumn and again in midwinter in locations where reduced sunlight and ultraviolet light occur.3 Using these recommendations, the total dose for the 1st cria would have been approximately 8,800–17,600 IU. Over 7 days this cria received 231,000 IU vitamin D3 (26,250 IU/kg), a 13-fold excess over the high end of the currently recommended range of dosing. The 2nd cria received 500,000 IU vitamin D3 over 5 days (64,900 IU/kg), a 29-fold excess above the high end of the currently recommended dosage range.3 This study provides objective data regarding normal serum vitamin D3 concentrations in camelids. The 1st study found that untreated, healthy alpaca cria (3–6 months of age) have serum 25-OH-vitamin D3 concentrations ranging from 11 to 115 nmol/L, whereas adult female alpaca (2–6 years of age) have 25-OH-vitamin D3 ranging from 39 to 437 nmol/L.3 In this study, cria and adult female alpaca were assigned to untreated, 1,000 IU vitamin D3/kg and 2,000 IU vitamin D3/kg by subcutaneous injections. Plasma concentrations of 25-OH-vitamin D3 in all treated animals were markedly increased by 2 days postdosing and remained significantly higher than the untreated cria for 4 weeks in the 1,000 IU/kg group, 7 weeks in the 2,000 IU/kg group.3 For adult female alpacas, all treated animals had increased plasma 25-OH-vitamin D3 for the duration of the study (16 weeks).3 None of the treated cria or adults achieved plasma 25-OH-vitamin D3 concentrations in the range observed in the 2 cria presented in this study. In a 2nd study, the plasma 25-OH-vitamin D3 concentrations in adult male alpacas (3–7 years of age) on pasture which were not supplemented with vitamin D3 ranged from 49 to 237.5 nmol/L (measured 4 times over a 9 month period).8 In a 3rd study, serum concentrations of 25-OH-vitamin D3 in vitamin D deficient llama and alpaca cria (age range 2–10 months) was determined to be 5.9 ± 1.4 nmol/L before vitamin D treatment, whereas 43 ± 10.6 days after treatment, mean serum 25-OH-vitamin D3 had increased to 259.9 ± 53.8 nmol/L.1 The treatment of vitamin D deficiency in this report included a single injection of 150,000 IU of 25-OH-vitamin D3, or 33,000 IU of 25-OH-vitamin D3 PO every 2 weeks, or a single oral dose of 100,000 IU vitamin D3 monthly.1 Clinically normal herdmate 25-OH-vitamin D3 were 91 ± 12.4 nmol/L in animals ranging in age from 1 to 85 months.1 It should be noted that these treatments were provided to older cria (2–10 months of age; greater body weights), and the oral supplementation was sufficient to increase alpaca or llama cria serum 25-OH-vitamin D3 concentrations.1 The 2 cria in this report presented with serum 25-OH-vitamin D3 concentrations of 663 nmol/L (Cria #1) and 602 nmol/L (Cria #2), which exceed values reported for vitamin D3 in normal 3–6-month-old camelid cria, in unsupplemented adult male alpacas as well as vitamin D3 deficient llama and alpaca cria after supplementation with injectable or oral forms of 25-OH-vitamin D3.1,3,8 The 2 cria reported on here received vitamin D3 supplementation via oral dosing, whereas the alpacas and llamas reported previously received vitamin D supplementation by either subcutaneous injection or oral dosing. Further, the studies we cited for comparison provided supplementation via a single parenteral dose (1–2,000 IU/kg) or oral dosing (no body weights given) either once or twice monthly.1,3,8 As a result, the crias reported here developed high serum and tissue concentrations of vitamin D3 as a result of oral supplementation at frequent intervals and over sequential days. The total oral dose, total cumulative dose/kg body weight, and daily oral dose/kg bodyweight, resulted in 231,000 IU total, 26,250 IU/kg cumulative, or 3,750 IU/kg/d over 7 days in Cria #1; and 500,000 IU vitamin D3 total, 64,900 IU/kg cumulative, or 12,987 IU/kg/d PO over 5 days in cria #2. We believe that high total dose and repeated dosing appear to be critical for development of increased serum and tissue concentrations of vitamin D metabolites. For example, Van Saun9 treated a single adult alpaca with 1 dose of 64,000 IU/kg vitamin D with no signs of acute intoxication, suggesting accumulation over time may be important. Since North American cria consuming milk likely have limited intake of vitamin D and are rapidly growing, it has been suggested that supplementation during periods of reduced sunlight and UV radiation is necessary to prevent vitamin D deficiency. Van Saun currently recommends daily vitamin D intake of 30 IU/kg to maintain requirements for most camelids.9 Increased vitamin D metabolites result in hyperphosphatemia and hypercalcemia after excessive absorption of calcium and phosphorus from the intestine, renal tubular reabsorption of calcium and phosphorus, and mobilization of calcium and phosphorus from bone. Extensive soft tissue mineralization occurs because of the insolubility of calcium and phosphorus at high concentrations. Nephropathies with mineralization of tubular basement membranes is a classic lesion of hypervitaminosis D in many species.10–14 In addition to these lesions, concurrent mineralization of the glomerular membrane was prominent in both of these cria, which has only been described sporadically in dogs with hypervitaminosis D.15,16 While mineralization of the glomerular basement membranes appears uncommon in canine or feline hypervitaminosis D, it might represent a species variation of this disease in camelids. Mineralization of tubular casts seen in histopathologic specimens from one of our cases is a finding that has also been described in cows and a dog with hypervitaminosis D.12,16 It is also possible these lesions may reflect repeated dosing with high doses of vitamin D. Lesions consistent with ischemic tubular injury were evident in histopathologic sections of both of the cria reported here. Later, mineralization of the tubules and glomeruli would cause further loss of functional renal tissue.12 Both cria had extensive renal mineralization at necropsy. The high levels of 25-OH-vitamin D in the renal tissue of both cases indicates hypervitaminosis D as the likely cause for tissue mineralization.16 The combined findings of persistent azotemia and hypercalcemia are difficult to assess without measurement of ionized calcium. Renal failure can result in increased serum calcium concentrations with or without an associated increase in ionized calcium.17 Furthermore, ionized hypercalcemia can result in both acute and chronic renal injury.17 Only ionized calcium is thought to contribute to mineralization and other damaging effects of hypercalcemia. It is well known that dogs with chronic renal failure can develop hypercalcemia not associated with an increase in ionized calcium.17 The ionized calcium concentrations determined in these cria were elevated (1.79 and 1.60 mmol/L in cases 1 and 2, respectively). Thus, it is likely that increased ionized calcium was responsible for the pattern of tissue mineralization associated with increased 25-(OH)-vitamin D concentrations. As ionized calcium was elevated in the face of low serum albumin, we believe this confirms the increased total serum calcium concentrations observed in both cria were associated with functional increases in ionized calcium. More importantly, increased total and iCa concentrations in the face of increased 25-(OH)-vitamin D3 are likely the result of cholecalciferol toxicity. The finding of anuria attests to the severity of the renal injury in these 2 cases. Most dogs with hypervitaminosis D do not develop anuria and can survive with aggressive supportive treatments.17 An important goal of treatment is to rapidly decrease the hypercalcemia and hyperphosphatemia. Peritoneal dialysis, as used in case #2, is one mechanism to lower serum calcium. In this cria, dialysis was associated with normalization of serum calcium within 3 days; however, anuria persisted and azotemia worsened. The reduction in serum calcium may have resulted from the peritoneal dialysis. However, prolonged increases in ionized calcium and phosphorous concentrations may also have resulted in further tissue mineral precipitates contributing to further reductions in serum calcium. Furosemide, a calciuretic diuretic, was used in both cria; however, it also was not successful in stimulating urine production or lowering serum calcium. Furosemide must first be secreted by the proximal tubule into renal tubular fluid before it can exert its calcium lowering effect more distally on the ascending loop of Henle. It is likely that furosemide was not able to be adequately secreted by the extensively damaged tubules of the cria in this report. Vitamin D is an important supplement for crias, when used at appropriate doses. This report documents that repeated, oral supplementation of camelids with excessive doses of vitamin D can induce fatal toxicity as observed in other species. Furthermore, products containing vitamin D should be used judiciously in neonatal crias born in the fall and winter, and dosages should not exceed current recommendations for South American camelids. Explicit dosing instructions should be provided to clients to allow safe administration. Cria presenting with increased serum concentrations of calcium and phosphorus, renal dysfunction, and historical use of vitamin D should undergo diagnostic imaging with radiographs and or ultrasonography to evaluate the presence of soft tissue mineralization. These findings may be important prognostically while awaiting toxicological confirmation. Measurement of 25-(OH)-vitamin D should be performed in all patients suspected for hypervitaminosis D as this metabolite is the maker for vitamin D intake since vitamin D is rapidly converted to this metabolite. In those already in renal failure, it is essential to also measure ionized calcium, as discordance between ionized and total calcium is known to be severe in other species with renal failure. Early recognition and correction of hypercalcemia initially by IV administration of fluids for rehydration and return of urine production are critical. Although not used in the 2 cria described in this report, the role of glucocorticoids, furosemide, bisphosphonates, and phosphate binding agents as treatments for hypercalcemia and hyperphosphatemia associated with hypervitaminosis D in camelids can have potential application in the South American camelid; however, their use requires further investigation. a Naxcel, Pharmacia and UpJohn, Kalamazoo, MI b Kaeco Colostrum Powder for goats, Kaeco Group, Savannah, MO c Humulin R, Eli Lilly, Indianapolis, IN d Furosemide, Equi-Phar Furosemide injection 5%; VEDCO Inc, St Joseph, MO e Diagnostic Center for Population and Animal Health, Michigan State University, Lansing, MI f Tenckhoff, Acute Peritoneal Dialysis Catheter, Cook Medical Inc, Bloomington, IN g Dianeal PD-2 1.5 peritoneal dialysis solution, Baxter, Deerfield, IL The authors gratefully acknowledge the support of the Department of Veterinary Clinical Sciences of The Ohio State University, College of Veterinary Medicine.