Abstract
Objective
To describe and compare clinical and laboratory findings in alpacas with hypofructosaminemia (fructosamine low [FL]), normofructosaminemia, and hyperfructosaminemia (fructosamine high [FH]) in order to identify associations of abnormal plasma fructosamine (PF) with other clinical and laboratory findings in alpacas.
Methods
A retrospective observational study was conducted with clinical and laboratory data of 125 alpacas with FL (PF < 252 µmol/L; n = 19), normofructosaminemia (PF, 252 to 425 µmol/L; n = 93), and FH (PF > 425 µmol/L; n = 13) presented to a veterinary teaching hospital from January 2022 through January 2023. Findings of the animals were compared using descriptive statistics and comparisons (Kruskal-Wallis test, 1-way ANOVA, t test, or Mann-Whitney U test). Resulting diagnoses were tested for associations with fructosamine using the 2-sided Fisher exact test.
Results
FL occurred more frequently in crias than adults and was associated with lower bodyweight, body condition score, PCV, total protein, albumin, and globulin. Hyperfructosaminemia was associated with hyperglycemia. While a large proportion of the alpacas with FL had cachexia (8 of 19) and/or anemia (6 of 19), the alpacas with FH were given many different diagnoses.
Conclusions
The available data suggest that FH in alpacas is associated with hyperglycemia, whereas FL is associated with decreased plasma proteins and poor nutritional status.
Clinical Relevance
PF is rarely used in routine diagnostics in alpacas, but it can aid in the interpretation of plasma glucose, plasma proteins, and nutritional status.
Hyperglycemia is a common finding in South American camelids (SACs; alpacas and llamas). Eighty-nine of 125 (more than 70%) of SACs presented for veterinary care to our clinic showed an elevated plasma glucose level.1 The glucose metabolism of camelids differs substantially from other ruminating species as they show a comparatively weak insulin response and hence a slow cellular uptake of glucose.2,3 Even minimal stress can lead to plasma glucose levels of > 200 mg/dL (> 11.1 mmol/L) in alpacas or llamas, which can last for several hours.4 It is, however, often unclear whether hyperglycemia should be interpreted as an acute stress response or whether it is a chronic metabolic condition requiring treatment.
A laboratory parameter from human medicine that provides information about the plasma glucose level over a longer period of time is plasma fructosamine (PF).5 The measurement of fructosamine has been established in diabetic dogs and cats for many years.6 The term “fructosamine” refers to glycated proteins resulting from the reaction of albumins or other plasma proteins and sugars and is the trivial term for 1-amino-1-deoxyfructose.5 In contrast to plasma glucose, PF concentration in humans provides an overview of the glucose level over the preceding 2 to 3 weeks.5,7 On the one hand, this parameter can be used in the diagnosis and metabolic control of diabetes8; on the other hand, it can help to correctly classify hyperglycemia or glucosuria in species (eg, cats) that are very agitated when presented to the veterinarian.9 Besides companion animals, the measurement of fructosamine for monitoring plasma glucose has also been established in livestock, like cattle or small ruminants.10–12 In addition to plasma glucose, PF is also suitable for the interpretation of plasma protein findings,1,13,14 which could also be relevant for SACs, where hypoproteinemia is a common condition.1,4,15
Data on fructosamine in SACs are, however, scarce. In a study on biochemical reference values, Dawson et al16 examined a total of 74 clinical healthy adult alpacas of both sexes from 5 different farms and gave a reference range of 252 to 425 µmol/L for PF (or 251 to 431 µmol/L for serum fructosamine) in 2011.
Richter et al17 gave a similar range of 288 to 409 µmol/L for serum fructosamine for 3 healthy alpacas in a case study from 2006. In a recent study of 8 male and 12 female clinically normal llamas, the range for PF (254.8 to 409.2 μmol/L) was similar to the findings previously reported in alpacas.18 The PF of male llamas was significantly higher than that of females. In addition, significant positive correlations of PF with glucose, total protein (TP), albumin, PCV, hemoglobin (Hb), calcium, sodium, and selenium were observed.18
In another recent study,1 we characterized PF and several other biochemical and hematological parameters in 125 alpacas presented to our clinic in relation to stress. In the investigated population, 13 alpacas with hyperfructosaminemia (> 425 µmol/L [10.4%]) and 19 alpacas with hypofructosaminemia (< 252 µmol/L [15.2%]) were identified. To the best of our knowledge, there are no data available yet on the clinical findings of alpacas with hyper- or hypofructosaminemia. Hence, the aim of the current study is to characterize and compare clinical and laboratory findings as well as the outcome of hospitalized alpacas with PF concentrations within, above, and below the reference interval (RI). Further, the final diagnoses in alpacas with abnormal PF concentrations are characterized.
Methods
Data collection
In 125 alpacas presented as patients to a veterinary teaching hospital from January 2022 through January 2023, routine plasma samples were collected during the initial clinical examination and consecutively analyzed for fructosamine in the clinic’s own laboratory using the Cobas Mira Plus (Roche Diagnostics Corp) with a Fruktosamin kit (Labor + Technik Eberhard Lehmann GmbH).18 As the clinic’s own references were not available, the RI for fructosamine from Dawson et al16 was used for interpretation. The alpacas were divided into 3 groups depending on their PF concentration: hypofructosaminemia (PF < 252 µmol/L; “fructosamine low” [FL]; 15.2%; n = 19), normofructosaminemia (PF = 252 to 425 µmol/L; “fructosamine normal” [FN]; 74.4%; n = 93), and hyperfructosaminemia (PF > 425 µmol/L; “fructosamine high” [FH]; 10.4%; n = 13).1 Further data of these animals were assessed in the initial examination of the animals and were compared between the 3 groups: sex (male, female); age at presentation (days), with the age also expressed as the categorial variable “crias” (< 1 year; n = 20) and adult animals (≥ 1 year; n = 102), but age information was not available for 3 animals, and these were not included in the analyses where age was a factor; bodyweight (BW; kilograms); duration of hospitalization (days); rectal temperature (RI, 38.0 to 38.9 °C19); respiratory rate (1/min; RI: adults, 15 to 30; crias, 20 to 3019); heart rate (1/min; RI: adults, 60 to 80; crias, 70 to 10019); body condition score (BCS; RI, 2.5 to 3.520); PCV (L/L; RI, 0.22 to 0.4521); WBC count (109/L; RI, 7.1 to 18.621); lymphocytes (109/L; RI, 1.1 to 5.521); neutrophils (109/L; RI, 3.5 to 11.721); band neutrophils (109/L; RI, 021); eosinophils (109/L; RI, 0.1 to 4.321); basophils (109/L; RI, 0 to 0.421); monocytes (109/L; RI, 0 to 1.021); glucose (mmol/L; RI, 5.50 to 7.9416); TP (g/L; RI, 58 to 7316); albumin (g/L; RI, 28 to 43 16); globulin (g/L; RI, 22 to 3416); albumin-to-globulin (A:G) ratio (0.9 to 1.716); and fructosamine-to-albumin (F:A) ratio (µmol/g; no RI available). The neutrophil-to-lymphocyte ratio (NLR) was calculated according to the following formula: (neutrophils + band neutrophils + metamyelocytes + myelocytes)/lymphocytes (RI, 0.5 to 2.9 22).
Clinical examination of the animals was performed in accordance with the clinic’s routine protocol: measurement of rectal temperature was done with a digital thermometer, and respiratory rate and heart rate were determined by auscultation. Assessment of the BCS in our clinic has been described in detail elsewhere.23 Blood samples were taken from the jugular vein of the animals24 (EDTA, Monovette 9 mL K3E; lithium-heparin, Monovette 9 mL LH; Sarstedt AG & Co KG), plasma was centrifuged for 15 minutes at 2,000 X g within 30 minutes after sampling, and the supernatant was transferred to a new tube and stored at −20 °C until further processing. The measurement of hematologic parameters was performed according to the routines of the clinic’s laboratory25 by using manual standard methods (centrifugation of PCV, photometrical measurement of Hb with cyan solution, counting of WBCs in a counting chamber, and differentiation of 200 cells in a blood smear). The same table-top analyzer (Cobas Mira Plus; Roche Diagnostics Corp) was used for all measurements of plasma concentrations of glucose, TP, and albumin with commercially available kits (glucose kit, Gesamt-Eiweiß kit, and albumin kit; Labor + Technik Eberhard Lehmann GmbH). Globulins were calculated by subtracting albumin from TP. The A:G ratio was calculated by dividing albumin by globulin. The F:A ratio was calculated by dividing fructosamine by albumin. Fecal samples of the animals were processed as described before,1 and the amount of the shed gastrointestinal nematode (GIN) eggs was determined microscopically after flotation in saturated saline solution (GIN-Score). The severity of the infestation with GINs was evaluated semiquantitatively (no, low grade, medium grade, high grade, severe).1,26 The duration of hospitalization (days) and the outcome (discharged, died, euthanized) were indicated for each animal. The final diagnoses were only evaluated for FL and FH and divided into clinical diagnoses, etiological diagnoses, and pathological diagnoses.
The study was approved by the ethics committee of the University of Veterinary Medicine Hannover (approval code: TiHo_EA_14_02-25). Written informed consent was obtained from all animal owners.
Statistical analysis
Statistical analyses were performed with standard software (SAS Enterprise Guide, version 7.1; SAS Institute Inc). Descriptive statistics were expressed as median, minimum, and maximum. Normal distribution was tested using the Shapiro-Wilk test. For the comparison of 2 groups, the t test was used for parameters with normally distributed data (Shapiro-Wilk test, P ≥ .05); otherwise, the Mann-Whitney U test was used. Differences of numerical parameters between 3 groups (FL, FN, and FH) were tested either with a 1-way ANOVA (Shapiro-Wilk test, P ≥ .05) or the Kruskal-Wallis test (Shapiro-Wilk test, P < .05). A t test with Bonferroni correction was used upon the ANOVA as a post hoc test. The Kruskal-Wallis test was followed by pairwise comparisons with the Wilcoxon test with correction according to the Dwass–Steel–Critchlow-Fligner method. A P value < .05 was considered significant. The analysis was performed for all animals and separated into crias and adult alpacas. Since there was only 1 cria in the FH group, only FL and FN were compared in the crias. For the FL and FN groups, the difference between adult alpacas and crias was tested.
By using the above-mentioned RIs, numerical clinical and laboratory diagnostic data were expressed as diagnoses (for example, hypothermia or lymphocytosis), which were presented as contingency tables to compare FL with FN, FH with FN, and FL with FH. The following categorical parameters (no/yes, unless otherwise indicated) were considered: age (adult/cria), sex (female/male), released home, hypothermia, normothermia, hyperthermia, bradypnea, normopnea, tachypnea, bradycardia, normocardia, tachycardia, BCS decreased, BCS normal, BCS increased, GIN, PCV decreased, PCV normal, PCV increased, leukopenia, leukocytes normal, leukocytosis, neutropenia, neutrophils normal, neutrophilia, band neutrophils, eosinopenia, eosinophils normal, eosinophilia, basophilia, monocytosis, NLR decreased, NLR normal, NLR increased, hypoglycemia, normoglycemia, hyperglycemia, hypoproteinemia, normoproteinemia, hyperproteinemia, hypoalbuminemia, normoalbuminemia, hyperalbuminemia, hypoglobulinemia, normoglobulinemia, hyperglobulinemia, A:G ratio decreased, A:G ratio normal, and A:G ratio increased.
The 2-sided Fisher exact test (FET) was used for testing data clustered into categories. The FET is similar to the χ2 test, but this test can also be used when a cell in the contingency table has a value of < 5. A P value of < .05 was assumed to be statistically significant in each case. The OR and its 95% CI were calculated for the contingency tables for which a P value of < .05 was obtained.
Results
The results for 102 adult alpaca (FL, n = 11; FN, n = 79; and FH, n = 12) and 20 crias (FL, n = 8; FN, n = 11; and FH, n = 1) were included. The age of another 3 FN alpacas was not known. The results for variables of interests were compiled, and descriptive statistics were compared between groups (Supplementary Tables S1–S6). Statistical comparisons of adults and crias can be found in Supplementary Table S7. The results of contingency tables of categorical parameters and the results of the FET as well as the OR and the CI are given in Supplementary Tables S8 to S16. Relevant results are further described in the following sections.
Demographic parameters
Overall, median age was significantly (P < .01) younger for alpacas in the FL group (568 days; range, 4 to 4,065 days) versus the FN (1,505 days; range, 3 to 6,657 days) or FH (1,756 days; range, 10 to 3,666 days) groups (Supplementary Tables S1 and S4). However, when adult alpacas and crias were considered separately, no statistical difference in median age was detected across groups of adults (P = .31) or crias (P = .59). Hypofructosaminemia was more frequently identified in crias (8 of 20 [40%]) than in adult alpacas (11 of 105 [10%]). For adults, the odds of being in the FL group were lower than being in the FN group (FET; OR, 0.19 [95% CI, 0.06 to 0.68]; P < .01) but higher than being in the FH group (FET; OR, 8.73 [95% CI, 0.93 to 81.49]; P < .05).
In terms of sex, no significant difference could be shown between the groups.
Clinical parameters
Bodyweight and BCS were significantly lower in the FL group (BW: 35.0 kg; range, 4.3 to 70.0 kg; BCS: 2.0; range, 1.0 to 3.0) than in the FH (BW: 59.0 kg; range, 7.7 to 110.0 kg; BCS: 3.0; range, 1.5 to 5.0) and FN groups (BW: 58.0 kg; range, 6.3 to 107.0 kg; BCS: 3.0; range, 1.0 to 5.0; Supplementary Tables S1 and S4). For animals with a BCS > 2.5, the odds of being in the FL group were lower than being in the FN group (FL-FN: FET; OR, 0.10 [95% CI, 0.03 to 0.32]; P < .001). When considering BW of the adult alpacas separately, as this parameter was significantly lower for the crias due to their smaller body size (Supplementary Table S3), a lower median BW was observed in the adult alpacas of the FL group (n = 11; 43.0 kg; range, 22.8 to 70.0 kg) compared to the FH (n = 12; 59.0 kg; range, 35.0 to 110.0 kg; P < .001) and the FN groups (n = 69; 63.0 kg; range, 21.0 to 106.0 kg; P < .01; Supplementary Tables S2 and S5).
There was no difference in the weight of the crias between the FL (n = 7; 9.7 kg; range, 4.3 to 36.0 kg) and FN groups (n = 8; 16.8 kg; range, 6.3 to 30.0 kg; P = .39). Animals with deviations in PF further showed more frequent deviations of heart rate (Supplementary Table S3). The odds of being in the FL or FH group were higher than being in the FN group for animals that revealed no normocardia (FL-FN: FET; OR, 10.63 [95% CI, 2.29 to 49.36]; P < .001; FH-FN: FET; OR, 7.79 [95% CI, 1.63 to 37.30]; P < .01). This finding was also significant for the adults but not for the crias (Supplementary Tables S11, S12, S14, and S15).
The comparison of adults and crias revealed a significantly higher heart rate in crias in the FN group (Supplementary Tables S2, S3, and S7).
No differences were found in the GIN-Score of the adult animals, but the GIN-Score of the hypofructosaminemic crias was lower than that of the normofructosaminemic crias (P = .04; Supplementary Tables S3 and S6). Adult alpacas with hyperfructosaminemia more often revealed hyperthermia (3 of 9 [33.3%]) than adults with normofructosaminemia (3 of 74 [4.1%]; FET; OR, 0.12 [95% CI, 0.02 to 0.70]; P = .03; Supplementary Table S12). However, this was not observed in the crias (Supplementary Table S15). No statistical differences were identified for the respiratory rate.
Hematological parameters
Among the hematological parameters, median PCV was significantly (P < .001) lower for alpacas in the FL group (0.20 L/L; range, 0.05 to 0.30 L/L) versus the FN (0.28 L/L; range, 0.06 to 0.39 L/L) or FH (0.33 L/L; range, 0.23 to 0.44 L/L) groups (Supplementary Tables S1 and S4). Comparable results were obtained after splitting the adults (Supplementary Tables S2 and S5). While a similar trend was observed when comparing crias with hypo- (0.26 L/L; range, 0.20 to 0.30 L/L) and normofructosaminemia (0.29 L/L; range, 0.22 to 0.39 L/L), this turned out to be not significant (P = .06; Supplementary Tables S3 and S6). There were more anemic alpacas in the FL group (8 of 11 [72.7%]) than in the FN group (9 of 84 [10.7%]; FET; OR, 0.15 [95% CI, 0.05 to 0.46]; P < .01; Supplementary Table S8).
Furthermore, there were alterations in the WBC count depending on the fructosamine group: leukopenia was more frequently observed in alpacas in the FH group (5 of 8 [62.5%]) than in the FN group (9 of 83 [10.6%]; FH-FN: FET; OR, 0.17 [95% CI, 0.05 to 0.64]; P = .01; Supplementary Table S9).
Alpacas with hypo- (5 of 19 [26.3%]) or hyperfructosaminemia (4 of 9 [44.4%]) were more likely to have neutropenia than those with normofructosaminemia (7 of 85 [8.2%]). The odds of an animal in the FL or FH group not having neutropenia were lower than for those in the FN group (FL-FN: FET; OR, 0.23 [95% CI, 0.06 to 0.83]; P = .03; FH-FN: FET; OR, 0.19 [95% CI, 0.05 to 0.76]; P = .03; Supplementary Tables S8 and S9). However, after splitting into age groups, similar findings were not observed the crias, for the adults only for the comparison FH-FN (Supplementary Tables S11, S12, S14, and S15). In the crias, on the other hand, associations between fructosamine and the lymphocyte count were found: in the FL group, 50% of the crias (4 of 8) showed deviations in the lymphocyte count, whereas no changes in the lymphocyte count were found in the FN group (0 of 11 [0%]; FL-FN: FET; OR, 3.75 [95% CI, 1.62 to 8.70]; P = .02; Supplementary Table S14).
No statistical differences were found between the compared groups for the other investigated hematological parameters (Supplementary Tables S1–S6).
Significantly higher lymphocytes and lower eosinophils were found in the crias compared to the adults in the FN group (Supplementary Tables S2, S3, S7).
Biochemical parameters
Animals in the FL group had significantly (P < .01) lower median plasma concentrations of TP (53.0 g/L; range, 27.2 to 63.4 g/L), albumin (31.0 g/L; range, 15.1 to 40.5 g/L), globulin (21.0 g/L; range, 12.1 to 29.9 g/L), and F:A ratio (6.27; range, 5.59 to 9.48) than the animals of the FN (TP: 65.5 g/L; range, 44.9 to 86.5 g/L; albumin: 38.8 g/L; range, 24.3 to 48.8 g/L; globulin: 27.1 g/L; range, 13.4 to 59.4 g/L; F:A ratio: 8.51; range, 6.48 to 13.55) or FH (TP: 71.4 g/L; range, 55.3 to 88.7 g/L; albumin: 40.6 g/L; range, 30.0 to 48.9 g/L; globulin: 28.3 g/L; range, 21.7 to 47.5 g/L; F:A ratio: 12.40; range, 9.90 to 21.20) groups; no differences were found for the A:G ratio (Supplementary Tables S1 and S2).
Differentiated by age, however, there was no statistical difference in plasma globulin in the adult alpacas (P = .09), whereas crias in the FL group had less globulin (14.0 g/L; range, 12.1 to 22.9 g/L) than crias in the FN group (21.5 g/L; range, 13.4 to 36.5 g/L; P < .01; Supplementary Tables S2, S3, S5, and S6). More animals in the FL group were affected by hypoproteinemia (17 of 19 [89.5%]; FET; OR, 0.01 [95% CI, 0.002 to 0.05]; P < .001), hypoalbuminemia (7 of 19 [36.8%]; FET; OR, 0.08 [95% CI, 0.02 to 0.31]; P < .001), and hypoglobulinemia (10 of 19 [52.6%]; FET; OR, 0.21 [95% CI, 0.07 to 0.59]; P < .01) than in the FN group (7 of 85 [8.2%], 4 of 87 [4.6%], and 17 of 74 [23.0%], respectively; Supplementary Table S8). However, there were no statistical differences in the FET for TP, albumin, globulin, and A:G ratio between the FN and FH groups (Supplementary Table S9).
Crias had significantly (P = .04) higher median plasma albumin concentrations in the FL group (37.0 g/L; range, 15.1 to 40.5 g/L) and significantly higher plasma globulin concentrations in the FL (14.0 g/L; range, 12.1 to 22.9 g/L; P < .01) and FN (21.5 g/L; range, 13.4 to 36.5 g/L; P < .01) groups than adults (albumin FL: 30.0 g/L; range, 21.3 to 36.5 g/L; globulin FL: 26.0 g/L; range, 14.9 to 29.1 g/L; globulin FN: 27.5 g/L; range, 17.4 to 59.4 g/L; Supplementary Tables S2, S3, and S7), which resulted in a higher A:G ratio in the crias than in the adults (adults’ FL: 1.30; range, 0.83 to 1.55; crias’ FL: 2.39; range, 1.25 to 2.95; adults’ FN: 1.39; range, 0.41 to 2.19; crias’ FN: 2.00; range, 1.23 to 2.58; FL, P < .01; FN, P < .001). Animals with hypofructosaminemia and concomitant hypoalbuminemia (7 of 19 [36.8%]) had a median BCS of 1.0 (range, 1.0 to 2.0), which was significantly lower (P < .01) than in the animals with hypofructosaminemia and normal plasma albumin (12 of 19 [63.2%]), where the BCS was 2.0 (range, 1.5 to 3.0).
For plasma glucose, there was no difference between the FL (adults: 7.9 mmol/L; range, 5.6 to 10.2 mmol/L; crias: 8.4 mmol/L; range, 4.2 to 18.6 mmol/L) and FN groups (adults: 9.1 mmol/L; range, 4.2 to 37.3 mmol/L; crias: 8.6 mmol/L; range, 6.7 to 27.6 mmol/L) in both adult alpacas (P = .10) and crias (P = .97), but animals in the FH group (all animals: 21.3 mmol/L; range, 8.4 to 31.1 mmol/L) had significantly (P < .001) higher plasma glucose concentrations than animals in the FN and FL groups (Supplementary Tables S1–S7).
More animals in the FH group (13 of 13 [100%]) showed hyperglycemia than animals in the FN (66 of 93 [71.0%]; FH-FN: FET; OR, 1.20 [95% CI, 1.09 to 1.32]; P = .04) or FL group (9 of 19 [47.4%]; FH-FL: FET; OR, 2.44 [95% CI, 1.48 to 4.04]; P < .01; Supplementary Table S8). Plasma glucose did not differ between adults and crias in the FN (P = .47) and FL (P = .39) groups (Supplementary Table S7).
Outcome
In total, 91 of 125 alpacas (72.8%; FN, 74 of 93 [79.6%]; FL, 9 of 19 [47.4%]; FH, 8 of 13 [61.5%]) were released from the hospital. While animals with hypofructosaminemia had higher odds of not being released (FL-FN: FET; OR, 4.33 [95% CI, 1.54 to 12.15]; P < .01; Supplementary Table S8), there were no numerical differences between the groups in the deceased animals (total, 18 of 125 [14.4%]; FN, 13 of 93 [14.0%]; FL, 3 of 19 [15.8%]; FH, 2 of 13 [15.4%]). However, a large proportion of the animals with deviations in initial PF were euthanized due to poor prognosis during hospitalization (total: 16 of 125 [12.8%]; FN, 6 of 93 [6.5%]; FL, 7 of 19 [36.8%]; FH, 3 of 13 [23.1%]).
The duration of hospitalization did not differ (P = .98) between the groups (FL: 5 days; range, 1 to 60 days; FN: 5 days; range, 1 to 47 days; FH: 6 days; range, 1 to 30 days) after splitting into adults and crias (Supplementary Tables S1–S6).
Diagnoses in alpacas with hypo- or hyperfructosaminemia
In some animals, more than 1 condition was diagnosed. Most diagnoses were clinical diagnoses; etiological diagnoses were only determined for individual animals depending on the performed diagnostic tests in each case. Pathological-anatomical or pathological-histological diagnoses were made in the animals that died or were euthanized and underwent necropsy. The final diagnoses, other than disorders of glucose metabolism, are shown in Table 1. The diagnoses of the animals in the FH group varied, with enteritis, gastric ulcers, and pneumonia each being mentioned twice. Among the animals in the FL group, an increased incidence of anemia (8 of 19 [42.1%]) and cachexia (6 of 19 [31.6%]) was observed in addition to various other diagnoses. One animal in the FH group was free of clinical signs, a dam (age, 1,756 days) that was admitted as a companion to its sick cria. Three of the alpacas in the FL group were free of clinical signs: a dam (age, 972 days) that was admitted as a companion to its sick cria as well as 2 crias, 1 (age, 26 days) as a companion to the sick dam and the other (age, 4 days) that had previously been noticed as dull but turned out to be clinically healthy at the clinic.
Final diagnoses other than disorders of glucose metabolism in alpacas with hyperfructosaminemia (FH; n = 13) and hypofructosaminemia (FL; n = 19) that were presented at a veterinary teaching hospital in Northern Germany from January 2022 through January 2023.
| Final diagnosis | No. of animals | Type of diagnosis |
|---|---|---|
| FH | ||
| Enteritis | 2 | P |
| Gastric ulcers | 2 | P |
| Pneumonia | 2 | C, P |
| Chorioptic mange | 1 | C, E |
| Colic | 1 | C |
| Myiasis | 1 | C |
| Peritonitis | 1 | P |
| Pododermatitis | 1 | C |
| Puerperal disorder | 1 | C |
| Salmonellosis | 1 | E |
| Thoracic tumor mass | 1 | C |
| FL | ||
| Anemia | 8 | C |
| Cachexia | 6 | P |
| Chorioptic mange | 3 | C, E |
| Diarrhea of unknown cause | 2 | C |
| Haemonchosis | 2 | C, E |
| Candidatus Mycoplasma haemolamae | 1 | E |
| Clostridiosis | 1 | E |
| Alveolitis with osteolysis | 1 | P |
| Eimeria macusaniensis | 1 | E |
| Enteritis | 1 | P |
| Esophageal impaction | 1 | E |
| Gastric ulcers | 1 | P |
| Meningitis | 1 | P |
| Recumbency and convulsions of unknown cause | 1 | C |
The diagnosis of "cachexia" was based on the necropsy findings.26 Therefore, this diagnosis could only be determined in those alpacas that underwent necropsy (n = 12). All alpacas with cachexia (6 of 12 necropsied alpacas [50%]) were in the FL group. Four necropsied alpacas without cachexia were in the FH group, but there were also 2 necropsied alpacas in the FL group without cachexia.
Discussion
After characterizing the clinical and laboratory findings from alpacas with either hypo- or hyperfructosaminemia, we identified differences concerning age, BW, BCS, PCV, and Hb as well as plasma glucose, TP, albumin, and globulin. Plasma fructosamine seems to be useful to distinguish chronic from acute hyperglycemia in alpacas.1 All animals in the FH group exhibited hyperglycemia, which can be classified as chronic hyperglycemia. Nevertheless, hyperglycemia was also observed in 10 of 19 animals in the FL group (52.6%) and 66 of 93 animals in the FN group (71.0%), which can be classified as acute hyperglycemia in these cases.1 The alpacas with deviations in PF in the present study were assigned to different final diagnoses. In the FH group, the final diagnoses varied, whereas in the FL group, anemia (8 of 19) and cachexia (6 of 19) dominated among other diagnoses. Anemia and poor nutritional status are major problems in the veterinary care of SACs and are diagnosed in a high proportion in the initial clinical examination in the alpacas presented at our clinic.27 There can be many reasons for anemia in alpacas, including blood loss or trace element deficiencies; the most common cause of severe anemia in alpacas is infection with Haemonchus contortus.28 However, it is not possible to identify a clear cause of anemia in every case. Moreover, cachexia is diagnosed in approximately every third SAC that undergoes necropsy (75 of 223 [33.6%]).29 Cachexia is usually associated with other conditions, and since it is usually a chronic process, it is difficult to identify a clear cause of cachexia in the pathological examination.29 In the present evaluation, a decreased BCS was observed more often in animals with hypofructosaminemia compared to individuals with PF concentrations within the RI. In both the adults and crias, the median BCS in the FL group was 1 score point lower than in the FN group (2.0 vs 3.0). Data from the aforementioned llamas from a previous study18 also indicated that a lower BCS was associated with lower PF. This association of BCS and fructosamine is also known from other species, like cattle,30 cats,31 or even elephants.32 In adults, the lower BCS of the FL group was also reflected in BW: animals with hypofructosaminemia had a median weight of 43.0 kg, 20 kg less than the animals with no deviations in PF (P = .02) and 16 kg less than the median weight of the animals with hyperfructosaminemia (P = .03). A positive correlation between BW and fructosamine has also been described for lambs33 and cats.31
Since poor nutritional status in alpacas often remains undetected for longer periods of time,4,29 it would be important to examine the nutritional status of the animal in more detail when hypofructosaminemia, which may be due to both prolonged hypoglycemia or hypoproteinemia, is diagnosed. The previous evaluation1 of the 125 alpacas showed a moderate positive correlation of fructosamine and glucose (r = 0.49; P < .001) as well as fructosamine and albumin (r = 0.50; P < .001) and a weak positive correlation of fructosamine and TP (r = 0.36; P < .001) but no significant correlation between fructosamine and globulin in the adult alpacas.1 However, crias revealed a significant moderate correlation of fructosamine and globulin (r = 0.65; P < .01) but no significant correlation between fructosamine and glucose. Crias further revealed moderate positive correlations of fructosamine and albumin (r = 0.54; P = .02) and TP (r = 0.69; P < .01).1 These results of the correlation analysis were presented in a more differentiated way through the group comparisons: while glucose showed no difference between FL and FN in both adults (P = .11) and crias (P = .97), the plasma glucose concentration in the adults with FH was significantly higher than FL (P < .001) and FN (P < .001). For TP and albumin, however, there was a difference between FL and FN (P < .001) as well as FH (P < .001) but not between FN and FH (P = .53). Globulins had to be considered differently by age. However, crias revealed lower globulins in both the FL (P < .01) and FN groups (P < .01), which might be attributed to lower immunoglobulins in the crias.34 While there was no difference between groups in adults (P = .09), crias with FL had lower plasma globulins than crias with FN (P < .01). These findings indicate that hyperfructosaminemia in alpacas is more likely due to increased plasma glucose, whereas hypofructosaminemia is more likely due to decreased plasma proteins.
In dogs and cats, hypofructosaminemia is closely associated with hypoalbuminemia and hypoproteinemia.13 According to Thoresen and Bredal,14 fructosamine in dogs can be used to assess the duration of hypoalbuminemia. If hypoalbuminemia and hypofructosaminemia are concurrently present, it can be assumed that the hypoalbuminemia had already persisted for more than a week, whereas normal albumin and concurrent hypofructosaminemia indicate recovery from hypoalbuminemia or hypoglycemia.14 If these conditions are applied to the alpacas from this study, 7 of the 19 alpacas with hypofructosaminemia and concomitant hypoalbuminemia would be considered to have prolonged hypoalbuminemia. The median of the BCS in these animals was 1.0 (range, 1.0 to 2.0), which was significantly lower (P < .01) than in the animals with hypofructosaminemia and normal plasma albumin, where the BCS was 2.0 (range, 1.5 to 3.0). This would support the hypothesis that the animals with both low plasma albumin and fructosamine were suffering from a chronic condition. The relationship between fructosamine and albumin can also be expressed as a F:A ratio.35 According to Agenäs et al,35 the F:A ratio can be used to detect undernutrition in cattle with high sensitivity and specificity. However, Strydom et al,36 who also investigated the F:A ratio in cattle, did not classify this as an accurate parameter to indicate undernutrition. In the alpacas presented here, the F:A ratio was significantly different between the groups (P < .001), with FL < FN < FH. These differences could be explained by the fact that the differences in fructosamine are caused by differences in albumin, globulins, or glucose. In the animals with hyperfructosaminemia, hyperproteinemia or hyperalbuminemia played only a minor role (3 of 12 animals each); hyperglobulinemia was not observed at all. All of those animals with hyperfructosaminemia also showed hyperglycemia. In the animals with hypofructosaminemia, however, only 1 animal was identified with hypoglycemia, whereas 17, 12, and 10 of 19 animals showed hypoproteinemia, hypoalbuminemia, and hypoglobulinemia, respectively. These findings turned out to be statistically significant in the FET (Supplementary Table S3). Nonetheless, these results must be considered in the context that plasma glucose levels can greatly fluctuate.
Infections with GINs, especially haemonchosis, play a major role in the veterinary care of SACs.37–39 The results from small ruminants suggest that PF is also closely related to the severity of endoparasitosis.31,40 In the present study, no differences in the GIN-Score between the groups were detected in the adults; the higher GIN-Score in the crias with normofructosaminemia compared to hypofructosaminemia remains unclear. In the clinic, many presented animals are dewormed just before presentation, which could bias the findings. However, the potential of fructosamine for parasite management in SACs should be investigated in further studies. A correlation between PF and PCV as well as Hb was already observed in clinically healthy llamas,18 but the relationship could not be clearly clarified there. In the alpacas in the present study that were suffering from 1 or more conditions, it could be assumed that hypofructosaminemia and concurrent anemia are both related to the poor nutritional status of the animals.27 The previous study1 already showed and discussed a weak positive correlation (r = 0.38; P < .001) between PF and PCV. Other hematological findings that stood out in animals with abnormal PF concentrations were leukopenia and neutropenia. Neutropenia is a sign of acute inflammatory processes and occurred more often in the FL and FH groups compared to the FN group. These findings indicate that the determination of PF might be a supportive parameter to detect inflammatory conditions in alpacas.
In summary, deviations in PF in alpacas reflect serious conditions, which is most evident in the outcome. Of the hospitalized alpacas with PF within the RI, a higher percentage were released home than those with hypo- or hyperfructosaminemia. In alpacas with hypofructosaminemia, anemia and cachexia were frequently found among the final diagnoses. Common findings in hypofructosaminemic animals were decreased BCS and decreased BW as well as hypoproteinemia, hypoalbuminemia, and anemia. Crias were significantly more likely to have hypofructosaminemia than adult alpacas. All alpacas with hyperfructosaminemia were hyperglycemic but showed no deviations with regard to plasma proteins. These animals had different final diagnoses. Our findings suggest that hyperfructosaminemia in alpacas is associated with hyperglycemia, whereas hypofructosaminemia is associated with decreased plasma proteins and poor nutritional status.
Supplementary Materials
Supplementary materials are posted online at the journal website: avmajournals.avma.org.
Acknowledgments
The authors would like to thank Frances Sherwood-Brock for her assistance with the linguistic correction.
Disclosures
The authors have nothing to disclose. No AI-assisted technologies were used in the composition of this manuscript.
Funding
Funded by the Open Access Publication Fund of the University of Veterinary Medicine Hannover, Foundation.
ORCID
M. G. Wagener https://orcid.org/0000-0003-3366-8579
References
- 1.↑
Kiene F, Buchallik-Schregel J, Röhrig P, et al. The measurement of plasma fructosamine as a diagnostic tool to improve the interpretation of plasma glucose and proteins in alpacas (Vicugna pacos). Sci Rep. 2024;14:22264. doi:10.1038/s41598-024-73399-4
- 2.↑
Cebra CK, Tornquist SJ, Van Saun RJ, Smith BB. Glucose tolerance testing in llamas and alpacas. Am J Vet Res. 2001;62(5):682–686. doi:10.2460/ajvr.2001.62.682
- 3.↑
Van Saun RJ. Nutrient requirements of South American camelids: a factorial approach. Small Rumin Res. 2006;61(2–3):165–186. doi:10.1016/j.smallrumres.2005.07.006
- 4.↑
Van Saun RJ. Nutritional requirements and assessing nutritional status in camelids. Vet Clin North Am Food Anim Pract. 2009;25(2):265–279. doi:10.1016/j.cvfa.2009.03.003
- 5.↑
Armbruster DA. Fructosamine: structure, analysis, and clinical usefulness. Clin Chem. 1987;33(12):2153–2163. doi:10.1093/clinchem/33.12.2153
- 6.↑
Reusch CE, Liehs MR, Hoyer M, Vochezer R. Fructosamine: a new parameter for diagnosis and metabolic control in diabetic dogs and cats. J Vet Intern Med. 1993;7(3):177–182. doi:10.1111/j.1939-1676.1993.tb03183.x
- 7.↑
Kaneko JJ. Carbohydrate metabolism and its diseases. In: Kaneko JJ, Harvey JW, Bruss ML, eds. Clinical Biochemistry of Domestic Animals. 5th ed. Academic Press; 1997:45–81.
- 8.↑
Miller E. Long-term monitoring of the diabetic dog and cat: clinical signs, serial blood glucose determinations, urine glucose, and glycated blood proteins. Vet Clin North Am Small Anim Pract. 1995;25(3):571–584. doi:10.1016/S0195-5616(95)50054-3
- 9.↑
Crenshaw KL, Peterson ME, Heeb LA, Moroff SD, Nichols R. Serum fructosamine concentration as an index of glycemia in cats with diabetes mellitus and stress hyperglycemia. J Vet Intern Med. 1996;10(6):360–364. doi:10.1111/j.1939-1676.1996.tb02081.x
- 10.↑
Sorondo ML, Cirio A. Evaluation of the serum fructosamine test to monitor plasma glucose concentration in the late-pregnant sheep. Anim Prod Sci. 2011;51(7):662–666. doi:10.1071/AN10244
- 11.
Sorondo ML, Cirio A. Evaluation of the serum fructosamine test to monitor plasma glucose concentration in the transition dairy cow. J Dairy Res. 2009;76(2):173–178. doi:10.1017/S0022029908003750
- 12.↑
Yatoo MI, Deepa PM, Mandal RSK, et al. Prevalence of subclinical diabetes in a commercial flock of dairy goats in India and its interaction with milk quality. Small Rumin Res. 2015;132:1–11. doi:10.1016/j.smallrumres.2015.09.012
- 13.↑
Pattullo KM, Kidney BA. Reference point: exploring fructosamine beyond diabetes mellitus. J Am Vet Med Assoc. 2014;244(11):1268–1277. doi:10.2460/javma.244.11.1268
- 14.↑
Thoresen S, Bredal W. An evaluation of serum fructosamine as a marker of the duration of hypoproteinaemic conditions in dogs. Vet Res Commun. 1998;22(3):167–177.
- 15.↑
Bildfell RJ, Löhr CV, Tornquist SJ. Diagnostic sampling and gross pathology of new world camelids. Vet Clin North Am Food Anim Pract. 2012;28(3):577–591. doi:10.1016/j.cvfa.2012.07.001
- 16.↑
Dawson DR, DeFrancisco RJ, Mix SD, Stokol T. Reference intervals for biochemical analytes in serum and heparinized plasma and serum protein fractions in adult alpacas (Vicugna pacos). Vet Clin Pathol. 2011;40(4):538–548. doi:10.1111/j.1939-165X.2011.00361.x
- 17.↑
Richter M, Grest P, Spiess B. Bilateral lipid keratopathy and atherosclerosis in an alpaca (Lama pacos) due to hypercholesterolemia. J Vet Intern Med. 2006;20(6):1503–1507. doi:10.1111/j.1939-1676.2006.tb00775.x
- 18.↑
Wagener MG, Kiene F, Buchallik-Schregel J, Röhrig P, Ganter M. Fructosamine in llamas (Lama glama) is associated with sex, body condition score, and hematologic and serum parameters. Am J Vet Res. 2024;85(10):ajvr.24.05.0140. doi:10.2460/ajvr.24.05.0140
- 19.↑
Whitehead C. Diseases in camelids 1: common presentations. In Pract. 2013;35(6):317–324. doi:10.1136/inp.f3641
- 20.↑
Wagener MG, Ganter M, Leonhard-Marek S. Body condition scoring in alpacas (Vicugna pacos) and llamas (Lama glama) – a scoping review. Vet Res Commun. 2024;48(2):665–684. doi:10.1007/s11259-023-10275-y
- 21.↑
Dawson DR, DeFrancisco RJ, Stokol T. Reference intervals for hematologic and coagulation tests in adult alpacas (Vicugna pacos). Vet Clin Pathol. 2011;40(4):504–512. doi:10.1111/j.1939-165X.2011.00359.x
- 22.↑
Hajduk P. Haematological reference values for alpacas. Aust Vet J. 1992;69(4):89–90. doi:10.1111/j.1751-0813.1992.tb15558.x
- 23.↑
Wagener MG, Ganter M. Body condition scoring bei Neuweltkamelen. Prakt Tierarzt. 2020;101:684–696. doi:10.2376/0032-681X-2020
- 24.↑
Gauly M, Maier H, Trah M. Blutentnahmetechnik und Referenzwerte relevanter klinisch-chemischer Blutparameter bei Neuweltkameliden. Tierarztl Umsch. 1998;53:751–754.
- 25.↑
Wagener MG, Grossmann T, Stöter M, Ganter M. Die hämatologische untersuchung bei lamas und alpakas. Prakt Tierarzt. 2018;99:481–493. doi:10.2376/0032-681X-18-10
- 26.↑
Neubert S, Puff C, Kleinschmidt S, et al. Gastric ulcers in alpacas—clinical, laboratory, and pathological findings. Front Vet Sci. 2022;9:877257. doi:10.3389/fvets.2022.877257
- 27.↑
Wagener MG, Neubert S, Punsmann TM, Wiegand SB, Ganter M. Relationships between body condition score (BCS), FAMACHA-score and haematological parameters in alpacas (Vicugna pacos), and llamas (Lama glama) presented at the veterinary clinic. Animals (Basel). 2021;11(9):2517. doi:10.3390/ani11092517
- 28.↑
Wagener MG, Marahrens H, Ganter M. Anaemia in South American camelids – an overview of clinical and laboratory diagnostics. Vet Res Commun. 2024;48(2):633–647. doi:10.1007/s11259-023-10274-z
- 29.↑
Neubert S, Puff C, Kleinschmidt S, et al. Pathological findings in South American camelids presented at a farm animal clinic in Northern Germany (2005–2021). Vet Res Commun. 2024;48(4):2121–2134.
- 30.↑
Roche JR, Macdonald KA, Schütz KE, et al. Calving body condition score affects indicators of health in grazing dairy cows. J Dairy Sci. 2013;96(9):5811–5825. doi:10.3168/jds.2013-6600
- 31.↑
Gilor C, Graves TK, Lascelles BDX, Thomson AE, Simpson W, Halpern DS. The effects of body weight, body condition score, sex, and age on serum fructosamine concentrations in clinically healthy cats. Vet Clin Pathol. 2010;39(3):322–328. doi:10.1111/j.1939-165X.2010.00227.x
- 32.↑
Norkaew T, Brown JL, Bansiddhi P, et al. Body condition and adrenal glucocorticoid activity affects metabolic marker and lipid profiles in captive female elephants in Thailand. PloS One. 2018;13(10):e0204965. doi:10.1371/journal.pone.0204965
- 33.↑
Stear MJ, Eckersall PD, Graham PA, McKellar QA, Mitchell S, Bishop SC. Fructosamine concentration and resistance to natural, predominantly Teladorsagia circumcincta infection. Parasitology. 2001;123(pt 2):211–218. doi:10.1017/S0031182001008253
- 34.↑
Bravo PW, Garnica J, Fowler ME. Immunoglobulin G concentrations in periparturient llamas, alpacas and their crias. Small Rumin Res. 1997;26(1–2):145–149. doi:10.1016/S0921-4488(96)00965-0
- 35.↑
Agenäs S, Heath MF, Nixon RM, Wilkinson JM, Phillips CJC. Indicators of undernutrition in cattle. Anim Welf. 2006;15(2):149–160. doi:10.1017/S0962728600030232
- 36.↑
Strydom S, Agenas S, Heath MF, Phillips CJC, Rautenbach GH, Thompson PN. Evaluation of biochemical and ultrasonographic measurements as indicators of undernutrition in cattle. Onderstepoort J Vet Res. 2008;75(3):207–213. doi:10.4102/ojvr.v75i3.96
- 37.↑
Ballweber LR. Ecto- and endoparasites of new world camelids. Vet Clin North Am Food Anim Pract. 2009;25(2):295–310. doi:10.1016/j.cvfa.2009.02.003
- 38.
Neubert S, von Altrock A, Wendt M, Wagener MG. Llama and alpaca management in Germany—results of an online survey among owners on farm structure, health problems and self-reflection. Animals. 2021;11(1):102. doi:10.3390/ani11010102
- 39.↑
Edwards EE, Garner BC, Williamson LH, Storey BE, Sakamoto K. Pathology of Haemonchus contortus in new world camelids in the southeastern United States: a retrospective review. J Vet Diagn Invest. 2016;28(2):105–109. doi:10.1177/1040638716628587
- 40.↑
Heath MF, Connan RM. Interaction of ostertagia and nematodirus species in sheep and the potential of serum fructosamine determination in monitoring gastrointestinal parasitism. Res Vet Sci. 1991;51(3):322–326. doi:10.1016/0034-5288(91)90085-3
