BRIEF COMUNICATION

Hematological parameters in shortnose guitarfish Zapteryx brevirostris Müller and Henle, 1841 (Chondrichthyes, Rhinobatidae)

 

Parámetros hematológicos en guitarra shortnose Zapteryx brevirostris especies Müller y Henle, 1841 (Chondrichthyes, Rhinobatidae)

 

Nathalia Barreto B,1 MV, Daniela Ferrer MV,2 Ph.D, Paula Baldassin,3 Ph.D, Denise Bobany M,2* M.Sc.

1Veterinary Medical autonomous.
2University Center Serra dos Orgãos – UNIFESO - Center of Science for Health - Course of Veterinary Medicine - Estrada da Prata s/n -Teresópolis – RJ –Brasil – CEP: 25.976-340.
3Veterinary Medical from Aquário de Ubatuba – Rua Ponciano Eugênio Duarte, 203 – Ubatuba -SP – Brasil – CEP: 11680-000.

*Correspondence: debobany@gmail.com

Received: October 2014; Accepted: March 2015.

ABSTRACT

Objective. In view of the deficiency of information in the area of clinical pathology of elasmobranchs, mainly of the physiological parameters, the aim of this work was to study hematological parameters of the Zapteryx brevirostris species. Materials and methods. Four specimens apparently healthy of Zapteryx brevirostris ; three females and a male were used. These animals are all pertaining ones to the Aquarium of Ubatuba, São Paulo (Brazil). Results. The obtained average of hematological values for the Zapteryx brevirostris were: Red Blood Cells were - 0.96 x 106/µL, Packed Cell Volume - 24.3% and White Blood Cells - 36.8 x 103/µL. Conclusion. Although the small N, which decreases the accuracy, this research has scientific value because the situation of vulnerability of Zapteryx brevirostris , suggesting other studies.

Key words: Clinical Pathology, elasmobranchs, hematology (Source: DeSC, BVS).

RESUMEN

Objetivo. En vista de la carencia de información en el área de patología clínica de los elasmobranquios, especialmente en lo que respecta a los parámetros fisiopatológicos, el objetivo de este trabajo fue el de obtener parámetros de la hematología de la especie Zapteryx brevirostris . Materiales y método. Cuatro animales clínicamente saludables de Zapteryx brevirostris ; tres hembras y un macho fueron utilizados, todos procedentes del Acuario de Ubatuba, S. P. Resultados. Los valores promedio de hematología para el Zapteryx brevirostris fueron: glóbulos rojos - 0.96 x 106/ µL, volumen de los hematíes - 24.3 % y glóbulos blancos 36.8 x 103/ µL. Conclusiones. A pesar de la pequeña N, que disminuye la precisión, la investigación tiene valor científico debido a que Zapteryx brevirostris es una especie vulnerable; sugiriendo otros estudios..

Palabras clave: Elasmobranquios, hematología, patología clínica (Fuente: DeSC, BVS).

INTRODUCTION

Brazil has extraordinary richness related to marine animals. However, little is known about the biology of each one of its forms, mainly regarding aspects of the disease in these animals and about the interactions between pathogens and hosts in natural environments.

The study of rays is of ecological interest because the invasion of man in the sea, so predatory, has caused great impact on the marine ecosystem, interfering not only in reproduction and survival of the rays, but also of countless beings to live there. The appreciation of the study of species in danger of extinction or vulnerable is of great importance for the ecological balance (1).

The Elasmobranchs are of great importance in the trophic chain, by the fact that they are animals of top or near the top of the marine food chain, and the decrease in its abundance can cause imbalance in trophic interactions within the community (2).

Only two genera of rays are found in the Brazilian coast, Zapteryx and Rhinobatos being that the genus Rhinobatos contains two species: Rhinobatos horkelli and Rhinobatos percellens, while the genre Zapteryx contains a single species: Zapteryx brevirostris , named commonly by “lane-viola short guy” or “banjo” (2,3).

It should be remembered that the species Zapteryx brevirostris is already considered vulnerable, as stated on the red list of Endangered Species, from 2006, the IUCN (International Union for Conservation of Nature and Natural Resources), and it takes 14 years to be able to have its population doubled (2).

Meet the blood values in order to obtain a better assessment of the State of health of animals is so important to the veterinary practitioner as are the history and physical examination of the animal, contributing to the diagnosis of possible changes caused by disease or other environmental factors.

Hematological tests are considered, although routines are still rare for fish. The few published works, mainly about the rays, are old, and the variables used in the studies as climate, geographic distribution, eating habits, destruction of natural habitats among others may have changed a lot since the preparation of same. These works provide fickle results regarding nomenclature, cellular differentiation, maturation and functioning of blood cells of fishes (4- 5).

Second Hrubec and Smith (4) hematological techniques used to mammals are generally applicable to fish with slight modifications and Stoskopf (6) reports that, until recently, the Hematology of fish was considered a technique post mortem.

The blood sample can be obtained by different ways; however, the caudal vein is used more often, even with the possibility of obtaining a sample straight from the heart (4).

The blood of rays easily suffers hemolysis, and therefore should be transferred immediately to a tube containing anticoagulant. The best results are obtained with 1 to 3 mL of blood in the syringe (4).

There are controversies regarding the type of anticoagulant to be used in the blood sample. A solution that combines two anticoagulant compounds, heparin and EDTA that seems to be more effective with Elasmobranch blood than either compound used individually (6).

Occasionally, if the fish is stressed, and the fish are very sensitive to manipulation, blood can clot even with the presence of blood thinner, and may not be visible in the tube, but preventing the correct count of thrombocytes and leucocytes (4).

Hrubec and Smith (4) state that the erythrocyte may vary with the different environments that the fish live and the water quality conditions, although these changes are not well characterized.

According to Smith et al (6), the count of leukocytes in hemocytometer is the best method to determine the total count of leukocytes of fish by eliminating the interference of the erythrocytes nucleus.

The aim of study was to investigate hematological parameters of Shortnose Guitarfish (Zapteryx brevirostris ), evaluating the techniques of collection and staining.

MATERIALS AND METHODS

Study location. This study was done with animals housed since April 2007 in the Aquarium of Ubatuba, northern coast of São Paulo- Brazil, Latitude -23.4509, Longitude -45.0647, Altitude 2 m and the Koeppen Classification climate: Af.

Animals in the study. Four animals were used of the Zapteryx brevirostris species being three females and one male.

Procedures performed. Although adults, animals had small sizes and weighed less than a pound each, therefore, due to low body weight was only possible withdrawal of 0.1 ml of blood for carrying out the examinations, contradicting the Hrubec and Smith (4) indication. The blood sample was collected by venipuncture, using a 1 ml syringe (syringe of insulin BD brand) and a needle 13 x 4.5 mm, of the ventral part of the tail, where is located the caliber caudal vein, as indicate Hrubec and Smith (4) and Smith et al (6). The animal was placed in a box containing saltwater and oxygenation and the whole procedure was done with the animal contained physically without using any anaesthetic drug as can be seen in figures 1A- 1B. This procedure causes stress, which can affect the results obtained.


Figure 1. A. Blood collection of a male specimen of the Zapteryx brevirostris species obtained of the caudal vein. B. Ideal place for venipuncture.

 

Immediately after venipuncture, blood was transferred to an eppendorf (Axygen) containing ethylene diamino-acid tetra-acetic acid (EDTA) (EDTA Vacutainer 26 BD). After the homogenization of blood with anticoagulant and the identification of eppendorf, the samples were processed in two locations: the entire count held in Newbauer Chamber (Boeco Germany) was made in the Aquário de Ubatuba and packed cell volume was sent in a private lab of the city, called MedLabor.

The eritrogram, with determination of red blood cell (hemocytometer) and packed cell volume (microhematocrit) was done using standard techniques and the leucogram, with determination only of white blood cell using the technique developed by Smith et al (6).

Ethical aspects. This study was approved by the Ethics Committee in dealing with Animals of UNIFESO, at the ordinary meeting held on 30/03/2007.

RESULTS

The results obtained for hematological values of one male and three females of the species Zapteryx brevirostris relative to Red Blood Cell (RBC), Packed Cell Volume (PCV) and White Blood Cells (WBC) are described in tables 1 and 2 respectively.

Table 1. Hematological Parameters values of an exemplary male of the Zapteryx brevirostris species.

 

Table 2. Hematological Parameters values of two females of the Zapteryx brevirostris species

The results of the means for hematological values of species Zapteryx brevirostris pertaining to red blood cell, packed cell volume and white blood cell are described in table 3.

 

Table 3. Hematological Parameters values for mean, standard deviation and range (minimum- maximum) in Zapteryx brevirostris (n = 3).

The animal’s blood number 1 (female) has undergone coagulation immediately after contact with blood thinner, so that animal was not considered in the statistical analysis of the data. During the procedure of collecting the blood sample on this copy it was observed that the same exhibited signs of stress, which may have caused the clotting of the extracted sample.

The use of the anticoagulant EDTA proved to be effective in its purpose when they were used in blood samples collected from specimens of species Zapteryx brevirostris , with exception of the animal n° 1.

DISCUSSION

The average values of red blood cell for Zapteryx brevirostris found in this work was 0.96 x 106/ mm3 with standard deviation of 0.48, less than reported by Rodrigues et al (7) which was of 0.343 x 106/ mm3 with standard deviation of 0.058. If compared with other species of the same genus, as in the case of Rhinobatos horkelli, this difference increases, because the average red blood cell is 0.303 x 106/ mm3, with standard deviation of 0.066. In addition to this fact, the averages found by the authors are also not within the values of the lower limit and upper limit described in this work, which are respectively 0.4 x 106/ mm3 and 1.5 x 106/mm3 for red blood cell.

The value of the packed cell volume found on this work was 24.3% with a standard deviation of 5.1 while Wilhelm Filho et al (8) reported a packed cell volume value for the sort Zapteryx brevirostris of 19.0% with standard deviation of 5.7. Brito (9) studying 53 specimens of four species of the genus Potamotrygon have found an average of 21.5% with standard deviation between 0,81 and 4,6 and Rodrigues et al (7) described a mean value for the packed cell volume of species Rhinobatos percellens of 20.5% and standard deviation of 0.5, greater than the value reported by Wilhelm Filho et al (8) to the packed cell volume 19.0% and standard deviation of 5.7 of species Zapteryx brevirostris . However, the averages of the values of packed cell volume (19.0% and 20.5%) cited by the authors are within the values of the range reported in this work are of 18.6% for the lower bound and 30.1% for the upper bound.

The average values for the white blood cell were not cited by any of the authors studied, thus the mean values found in this work, 36.8 x 103/ µL for white blood cell average, standard deviation of 9.03 and the range of 26.6 x 103/ µL for lower limit and 47.0 x 103/ µL for upper bound cannot be analyzed once are unpublished values for this hematological parameters for the species of rays.

Due to the low number of animals from Aquarium of Ubatuba available for the study, which decreases the accuracy, the hematological findings of Zapteryx brevirostris in this research should be considered as preliminary.

The reference ranges reported in this study are of scientific importance, due to the fact that the Zapteryx brevirostris be in a situation of vulnerability, and can be used to aid in the management of aquarium stingrays and to create a baseline for health monitoring of the Zapteryx brevirostris wild.

The results show that further studies should be made to better techniques of data collection and standardization of hematological parameters.

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