Comparative cell morphology in the peripheral blood film from exotic and native animals

Haematological investigation is an important part of disease diagnosis. This is particularly so when investigating individual animal disease. It may also be important when investigating diseases in groups of animals, but the opportunity to perform necropsies to directly detect diseases processes often diminishes its usefulness. Haematological investigation is essentially similar for all species. The presence of nucleated erythrocytes and thrombocytes in nonmammals requires alteration of haemoglobin measurement and cell counting. In addition, it may cause some confusion in identification of cells in peripheral blood films. Examination of blood films is an important component of haematological investigation and provides useful information on erythroid, leukocytic and platelet/thrombocytic alterations. Interpretation of alterations is essentially similar for all species. However, cell identification can at times be difficult. There are five basic leukocytes in all species: neutrophil (mammals) or heterophil (nonmammals), eosinophil, basophil, lymphocyte and monocyte. In nonmammals it may be difficult at times to distinguish between heterophils and eosinophils. In addition, lymphocytes may be confused with thrombocytes. However, a common-sense approach to the examination of the peripheral blood film will minimise this confusion.

Temporal effects of 3 commonly used anticoagulants on hematologic and biochemical variables in blood samples from macaws and Burmese pythons

BACKGROUND

Few studies have been done to evaluate anticoagulants for use with blood samples from birds and reptiles. Heparin currently is the most commonly used anticoagulant in practice, but may adversely affect blood cell staining and quantitation.

OBJECTIVE

The purpose of this study was to evaluate the effects of lithium heparin, K3-EDTA, and sodium citrate, with and without the addition of albumin, on hematologic variables in macaw (Ara sp) and python (Python molurus bivittatus) blood samples.

METHODS

Blood samples from 10 macaws and 10 Burmese pythons were collected in heparin-coated syringes and placed into tubes containing either lithium heparin, K3-EDTA, or sodium citrate with and without the addition of 0.25 mL of a 22% bovine serum albumin solution. Cell lysis was determined by counting the number of lysed cells/200 WBCs in Wright's-Giemsa-stained blood smears and by qualitative evaluation of pink plasma in microhematocrit tubes. A CBC was done after 3, 12, and 24 hours of storage at 4 degrees C in anticoagulant-containing tubes and results were compared with those obtained at 0 hour for the heparin-coated syringe sample. A biochemical panel also was done at each time point in similarly stored lithium-heparin samples.

RESULTS

Hemolysis was significantly increased in citrated samples from both macaws and pythons beginning at 12 hours. At 24 hours, 19 of 30 (63%) macaw samples in all anticoagulants had >100 lysed cells/200 WBCs. There were no significant differences in hematologic values in samples from pythons collected in heparin or EDTA at any time point. No significant differences were found in the number of lysed cells or in other hematologic data in samples with albumin. Glucose concentration decreased and potassium concentration increased significantly over time in heparinized blood samples.

CONCLUSIONS

Based on the results of this study, whole blood samples anticoagulated with lithium heparin or EDTA should be evaluated within 12 hours (macaws) or 24 hours (pythons) of collection and stored at 4 degrees C for best results. Citrate should be avoided as it may result in increased cell lysis. The addition of albumin does not prevent cell lysis.

Secretory phospholipase A2 activity in the normal and kainate injected rat brain, and inhibition by a peptide derived from python serum

The present study aimed to elucidate sPLA(2) activity in the normal and kainate-lesioned hippocampus using selective inhibitors of sPLA(2). In normal rats the highest levels of sPLA(2) were observed in the hippocampus, pons, and medulla, followed by the cerebral neocortex and caudate nucleus. After intracerebroventricular kainate injections an increase in total PLA(2) activity was observed in the rat hippocampus. Using a selective sPLA(2) inhibitor 12-epi-scalaradial, sPLA(2) activity was found to be significantly increased by 2.5-fold on the side of the intracerebroventricular injection compared to the contralateral side. A peptide P-NT.II, derived from the amino acid sequence of "PLA(2)-inhibitory protein," discovered in the serum of the reticulated python, also showed potent sPLA(2) inhibitory activity in homogenates from the kainate-injected hippocampus. These results show that there is a high level of sPLA(2) activity in the normal hippocampus, pons, and medulla oblongata, and that the level increases further in the hippocampus after kainate-induced excitotoxic injury. The increased PLA(2) activity was inhibited by P-NT.II, indicating a potential use of this peptide as a PLA(2) inhibitory agent in the brain.

Functional site of endogenous phospholipase A2 inhibitor from python serum

The functional site of 'phospholipase A2 inhibitor from python' (PIP) was predicted based on the hypothesis of proline brackets. Using different sources of secretory phospholipase A2 (sPLA2s) as enzyme, and [3H]arachidonate-labelled Escherichia coli as substrate, short synthetic peptides representing the proposed site were examined for their secretory phospholipase A2 (sPLA2) inhibitory activity. A decapeptide P-PB.III proved to be the most potent of the tested peptides in inhibiting sPLA2 enzymatic activity in vitro, and exhibited striking anti-inflammatory effects in vivo in a mouse paw oedema model. P-PB.III inhibited the enzymatic activity of class I, II and III PLA2s, including that of human synovial fluid from arthritis patients. When tested by ELISA, biotinylated P-PB.III interacted positively with various PLA2s, suggesting that the specific region of PIP corresponding to P-PB.III, is likely to be involved in the PLA2-PLI interaction. The effect of P-PB.III on the peritoneal inflammatory response after surgical trauma in rats was also examined. P-PB.III effectively reduced the extent of postsurgical peritoneal adhesions as compared to controls. sPLA2 levels at seventh postoperative day in the peritoneal tissue of P-PB.III-treated rats were also significantly reduced (P < 0.05) in comparison to those of the untreated controls. The present results shed additional insight on the essential structural elements for PLA2 binding, and may be useful as a basis for the design of novel therapeutic agents.

Increased blood oxygen affinity during digestion in the snakePython molurus

Many snakes exhibit large increases in metabolic rate during digestion that place extensive demands on efficient oxygen transport. In the present study,we describe blood oxygen affinity following three weeks of fasting and 48 h after feeding in the Burmese python (Python molurus). We also report simultaneous measurements of arterial blood gases and haematological parameters. Arterial blood was obtained from chronically implanted catheters,and blood oxygen-dissociation curves were constructed from oxygencontent measurements at known oxygen partial pressure(PO2) values at 2% and 5% CO2. Arterial pH remained constant at approximately 7.6 after feeding, but digestion was associated with an approximately 6 mmol l-1 increase in [HCO3-], while CO2 partial pressure(PCO2) increased from 2.21±0.13 kPa in fasted animals to 2.89±0.17 kPa at 48 h after feeding. Blood oxygen affinity in vivo was predicted on the basis of pH in vivoand the blood oxygen-dissociation curves obtained in vitro. The blood oxygen affinity in vivo increased during digestion, with P50 values decreasing from 4.58±0.11 kPa to 3.53±0.24 kPa. This increase was associated with a significant decrease in the red blood cell [NTP]/[Hb4] ratio (relationship between the concentrations of organic phosphates and total haemoglobin) and a significant decrease in mean cellular haemoglobin content, which is indicative of swelling of the red blood cells. Our data for blood oxygen affinity and arterial oxygen levels, together with previously published values of oxygen uptake and blood flows, allow for a quantitative evaluation of oxygen transport during digestion. This analysis shows that a large part of the increased metabolism during digestion is supported by an increased venous extraction, while arterial PO2(PaO2) and haemoglobin saturation do not vary with digestive status. Thus, we predict that venous PO2 (PvO2) is reduced from a fasting value of 5.2 kPa to 1.6 kPa during digestion.

Preliminary single-dose pharmacokinetics of marbofloxacin in ball pythons (Python regius)

Pharmacokinetics of marbofloxacin in two male and four female adult ball pythons (Python regius) was determined after i.v. and p.o. administration of a single dose. Using a crossover design, each snake was given a single 10 mg/kg dose of marbofloxacin i.v. and p.o. Blood samples were collected prior to and 0.5, 1, 1.5, 3, 6, 12, and 24 hr after marbofloxacin administration. Marbofloxacin was quantitated by use of liquid chromatography-mass spectrometry. Following p.o. administration, marbofloxacin had a peak plasma concentration (Cmax) of 9.40 microg/ml and a time to Cmax (Tmax) of 9.0 hr. Based on the plasma pharmacokinetics generated in this study and pending any further studies to evaluate potential toxicity and multi-dose pharmacokinetics, we suggest a dosage for marbofloxacin in ball pythons of 10 mg/kg p.o. at least every 48 hr, depending on the sensitivity of the pathogen and as a basis for further research.

SEASONAL INFLUENCE ON HEMATOLOGIC VALUES AND HEMOGLOBIN ELECTROPHORESIS IN BRAZILIAN BOA CONSTRICTOR AMARALI

As ectothermic animals, snakes depend exclusively on the environment for proper temperature maintenance, which may greatly influence their activity. Twenty-five adult Boa constrictor amarali snakes maintained in captivity were used to determine the influence of seasons on their hematologic values and electrophoretic profile of hemoglobin. A complete blood cell count (CBC) and examination for hemoparasites were performed in the summer and winter of 2004. Hemoglobin was stored for later electrophoresis. Significant differences (P < 0.05) were obtained in RBC, WBC, lymphocyte, thrombocyte, and monocyte counts, demonstrating the importance of the period of the year in the interpretation of reference values in these animals. Two snakes were detected with blood parasites (Hepatozoon sp.) in the winter and four in the summer, although it appears that their presence did not cause any significant alterations in the CBC. The electrophoretic analysis of the samples demonstrated two-four hemoglobin bands in this species.

Generation of [Ala1,Thr6]bradykinin in the plasma of a snake, the reticulated python

Incubation of heat-denatured plasma from the reticulated python, Python reticulatus with trypsin generated bradykinin-like immunoreactivity which was detected by radioimmunoassay using an antiserum raised against mammalian bradykinin. The primary structure of python bradykinin was established as Ala-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg. This amino acid sequence contains two substitutions (Arg1-->Ala and Ser6-->Thr) compared with mammalian bradykinin. Treatment of python plasma with glass beads under conditions previously shown to generate [Thr6]bradykinin in the plasma of a turtle and an alligator did not generate bradykinin-like immunoreactivity. The data indicate that the plasma of a lepidosaur contains a kininogen but, unlike the plasma of chelonians and crocodilians, does not contain a prekallikrein activator related to Factor XII.

BoaγPLI: Structural and functional characterization of the gamma phospholipase A2 plasma inhibitor from the non-venomous Brazilian snake Boa constrictor

Plasma in several organisms has components that promote resistance to envenomation by inhibiting specific proteins from snake venoms, such as phospholipases A2 (PLA2s). The major hypothesis for inhibitor's presence would be the protection against self-envenomation in venomous snakes, but the occurrence of inhibitors in non-venomous snakes and other animals has opened new perspectives for this molecule. Thus, this study showed for the first time the structural and functional characterization of the PLA2 inhibitor from the Boa constrictor serum (BoaγPLI), a non-venomous snake that dwells extensively the Brazilian territory. Therefore, the inhibitor was isolated from B. constrictor serum, with 0.63% of recovery. SDS-PAGE showed a band at ~25 kDa under reducing conditions and ~20 kDa under non-reducing conditions. Chromatographic analyses showed the presence of oligomers formed by BoaγPLI. Primary structure of BoaγPLI suggested an estimated molecular mass of 22 kDa. When BoaγPLI was incubated with Asp-49 and Lys-49 PLA2 there was no severe change in its dichroism spectrum, suggesting a non-covalent interaction. The enzymatic assay showed a dose-dependent inhibition, up to 48.2%, when BoaγPLI was incubated with Asp-49 PLA2, since Lys-49 PLA2 has a lack of enzymatic activity. The edematogenic and myotoxic effects of PLA2s were also inhibited by BoaγPLI. In summary, the present work provides new insights into inhibitors from non-venomous snakes, which possess PLIs in their plasma, although the contact with venom is unlikely.

Reproductive state and water deprivation increase plasma corticosterone in a capital breeder

Plasma corticosterone (CORT) concentrations fluctuate in response to homeostatic demands. CORT is widely recognized as an important hormone related to energy balance. However, far less attention has been given to the potential role of CORT in regulating salt and water balance or responding to osmotic imbalances. We examined the effects of reproductive and hydric states on CORT levels in breeding Children's pythons (Antaresia childreni), a species with substantial energetic and hydric costs associated with egg development. Using a 2 × 2 experimental design, we examined how reproduction and water deprivation, both separately and combined, impact CORT levels and how these changes correlate with hydration (plasma osmolality) and energy levels (blood glucose). We found that reproduction leads to increased CORT levels, as does dehydration induced by water deprivation. The combined impact of reproduction and water deprivation led to the largest increases in CORT levels. Additionally, we found significant positive relationships among CORT levels, plasma osmolality, and blood glucose. Our results provide evidence that both reproductive activity and increased plasma osmolality can lead to increased plasma CORT in an ectotherm, which could be explained by either CORT having a role as a mineralocorticoid or CORT being elevated as part of a stress response to resource imbalances.

Disposition of enrofloxacin and its metabolite ciprofloxacin after intramuscular injection in juvenile Burmese pythons (Python molurus bivittatus)

Eleven juvenile Burmese pythons (Python molurus bivittatus) weighing 0.75-1.75 kg were randomly divided into two groups. Blood samples were obtained through surgically placed anterior carotid artery cannulas. Six pythons received a single i.m. injection of enrofloxacin at 5 mg/kg. Blood samples were obtained at 0.5, 1, 3, 6, 12, 24, 48, 72, and 96 hr postinjection. A mean (+/- SD) maximal plasma concentration of 1.66 (+/- 0.42) micrograms/ml was measured at 5.75 hr postinjection. The harmonic mean half-life was calculated to be 6.37 hr. The second group of five snakes received enrofloxacin at 5 mg/kg i.m. s.i.d. for 5 days. Blood was collected immediately before each injection and at 6 hr after each injection. Over the 5-day period, there was a stepwise increase in mean trough plasma concentrations of enrofloxacin. Clinically effective peak plasma enrofloxacin concentrations were attained after the first injection but did not significantly increase during the sampling period. Pharmacokinetic data were assessed against minimum inhibitory concentrations of enrofloxacin for Pseudomonas ssp. isolates in snakes obtained from historical data at the Veterinary Medical Teaching Hospital, University of Florida. Enrofloxacin should be administered at 10 mg/kg i.m. every 48 hr when treating Pseudomonas ssp. infections in juvenile Burmese pythons. Treatment of infections of more enrofloxacin-sensitive gram-negative bacteria could be achieved with the administration of an initial i.m. dose of 10 mg/kg followed by 5 mg/kg every 48 hr.

Amikacin pharmacokinetics and the effects of ambient temperature on the dosage regimen in ball pythons (Python regius)

The serum concentration of amikacin following intracardiac and i.m. administration of amikacin (3.48 mg/kg) in 12 ball pythons (Python regius) housed at 25 degrees C and 37 degrees C was studied. Blood samples were collected by cardiocentesis at intervals up to 144 hr after administration of amikacin. Drug concentration-versus-time curves following intracardiac administration at both temperatures best fit a two-compartment open model. For snakes housed at 37 degrees C, the extrapolated time 0 concentration (mean +/- SD) was 17.64 +/- 3.5 micrograms/ml with a median elimination half-life of 4.5 days. The maximum concentrations were 11.98 +/- 1.67 micrograms/ml and 13.87 +/- 2.61 micrograms/ml for snakes housed at 25 degrees C and 37 degrees C respectively. There were no significant pharmacokinetic differences among the snakes housed at 25 degrees C and 37 degrees C. Model-independent parameters were area under the curve, 69,900 +/- 0.011 micrograms.min/ml, apparent volume of distribution at steady state, 410 +/- 106 ml/kg, clearance, 0.036 +/- 0.009 ml/min/kg, and mean residence time, 3,530 +/- 273.7 minutes. Mean serum amikacin concentrations did not reach the recommended therapeutic peak concentrations for mammals (25 micrograms/ml). In addition, the amikacin serum concentration did not fall below the recommended therapeutic trough concentrations (2 micrograms/ml) by 6 days. The serum amikacin concentrations were efficacious based on the area under the curve. Therefore, amikacin (3.48 mg/kg) administered i.m. to ball pythons should produce maximum serum concentrations against most pathogenic bacteria. In this study, it would have taken another half-life, or 4.5 days, before trough concentrations of 2 micrograms/ml were achieved. To prevent accumulation, a one-time administration of amikacin may be appropriate.

Laboratory reference values for a group of captive Ball Pythons (Python regius)

OBJECTIVE

Laboratory reference values, including hematologic and serum biochemical variables, and oropharyngeal bacteria flora, were determined in a group of captive Ball Pythons (Python regius).

ANIMALS

20 adult Ball Pythons, weighing between 700 and 1,510 g, were allowed to acclimate at the recommended temperature range for the species (25 C night-time, up to 30 C daytime), then were evaluated for internal parasites and treated with appropriate medication prior to the start of the study.

PROCEDURE

Hematologic values determined included WBC, hemoglobin, hematocrit, plasma protein, and differential cell count. Clinical biochemical analysis included determination of glucose, uric acid, calcium, phosphorus, total protein, alanine transaminase, alkaline phosphatase, and aspartate transaminase values. In addition to blood values, oropharyngeal swab specimens of the mouth were submitted for culture to determine the species of bacteria found in this population. Descriptive statistics were calculated for each hematologic and clinical biochemical value. Mean, SEM, and ranges were calculated.

RESULTS

Hematologic values were similar to those reported in other snake species, except the hematocrit, which was lower. Clinical biochemical values different from those of other species were alkaline phosphatase activity, which was lower, and calcium and phosphorus concentrations, which were lower than values in other species. Bacteria isolated from the oropharynx were principally gram-negative organisms.

CONCLUSION

Reference intervals reported in this study are important for establishing a database for comparative studies of Ball Pythons in other locations and under different husbandry conditions.

CLINICAL RELEVANCE

Accumulated laboratory reference values will assist veterinarians in assessing the health status of Ball Pythons.