Hematological profile of healthy Pantaneiro horses

Valores do hemograma em cavalos sadios da raça Pantaneiro

Abstract

Determinaram-se os valores do hemograma de 187 eqüinos sadios da raça Pantaneira. Para a composição de seis grupos experimentais consideraram-se a faixa etária e o sexo. Verificaram-se 6,2± 1,2 a 8,9± 2,3 hemácias/µl (x10(6)), 32,0± 4,0 a 37,0± 2,8% de volume globular (VG), 11,5± 1,0 a 12,8± 1,6g de teor de hemoglobina/dl, 11,0± 3,2 a 17,0± 2,8 leucócitos/µl (x 10³), 4,9± 1,8 a 7,5± 1,5 neutrófilos segmentados/µl (x 10³) e 5,2± 2,0 a 8,6± 2,0 linfócitos/µl (x 10³). Observaram-se valores mais baixos na contagem de hemácias, e VG e valores mais altos do volume globular médio (VGM) em cavalos castrados (acima de 25 meses de idade). As contagens de leucócitos e neutrófilos segmentados em potros com até oito meses de idade apresentaram valores mais elevados que os encontrados em animais acima dos 25 meses de idade. Constatou-se que não houve influência do sexo nos parâmetros analisados.

eqüino; raça Pantaneira; hemograma

horses; Pantaneiro breed; hematological profile

eqüino; raça Pantaneira; hemograma

COMMUNICATION COMUNICAÇÃO

Hematological profile of healthy Pantaneiro horses

Valores do hemograma em cavalos sadios da raça Pantaneiro

C.R. Ribeiro^I; J.J. Fagliari^I; P.D. Galera^II; A.R. Oliveira^III

^IFaculdade de Ciências Agrárias e Veterinárias - UNESP – Jaboticabal, SP

^IIFaculdade de Agronomia e Medicina Veterinária - UnB – Brasília, DF

^IIIUniversidade de Cuiabá – Cuiabá, MT

^{Endereço para correspondência (corresponding address)}

Keywords: horses, Pantaneiro breed, hematological profile

RESUMO

Determinaram-se os valores do hemograma de 187 eqüinos sadios da raça Pantaneira. Para a composição de seis grupos experimentais consideraram-se a faixa etária e o sexo. Verificaram-se 6,2± 1,2 a 8,9± 2,3 hemácias/µl (x10⁶), 32,0± 4,0 a 37,0± 2,8% de volume globular (VG), 11,5± 1,0 a 12,8± 1,6g de teor de hemoglobina/dl, 11,0± 3,2 a 17,0± 2,8 leucócitos/µl (x 10³), 4,9± 1,8 a 7,5± 1,5 neutrófilos segmentados/µl (x 10³) e 5,2± 2,0 a 8,6± 2,0 linfócitos/µl (x 10³). Observaram-se valores mais baixos na contagem de hemácias, e VG e valores mais altos do volume globular médio (VGM) em cavalos castrados (acima de 25 meses de idade). As contagens de leucócitos e neutrófilos segmentados em potros com até oito meses de idade apresentaram valores mais elevados que os encontrados em animais acima dos 25 meses de idade. Constatou-se que não houve influência do sexo nos parâmetros analisados.

Palavras-chave: eqüino, raça Pantaneira, hemograma

Pantaneiro horse is small in size (averaging= 137.7cm), docile, and rustic, having characteristics developed over the course of four centuries of natural selection in the Pantanal region of Mato Grosso, Brazil (Beck, 1985; Santos et al., 1995; Miserani et al., 2002). They are descendents of Andalucian and Lusitano horses of the Iberian peninsula (Cothran et al., 1998). The characteristics of Pantaneiro horses differ from those of other breeds due the need to adapt to the Pantanal environment. During its evolution, the Pantaneiro horse lost its aesthetic beauty and took advantage of zootechnical characteristics targeted for function. It developed a straight and tall frame, similar to that of a mule, conferring a tolerance to immersion in water for prolonged periods. Historically, this breed is used for working (e.g., cattle handling); however, currently, it is also being used for sporting due to notable physical capacity (Beck, 1985; Santos et al., 1995).

There is a vast literature with regard to hematological normal values for horses. Most of these are adult and athletic and whose physical conditioning and nutritional and hygienic management differ from the majority of the equine population, mainly with respect to the Pantaneiro breed (Lumsden et al., 1980; Tyler et al., 1987; Rose and Rodgson, 1994; Noronha et al., 2000; Feldman et al., 2000; Cunha et al., 2008).

Riding long distances, a type of endurance test that submits the animal to exercise of low intensity and long duration, has become a popular form of equestrian activity in the Pantanal region of Mato Grosso, Brazil (Ribeiro et al., 2004). Therefore, the knowledge of reference values for the hematological profile of healthy Pantaneiro breed horses, both males and females, of different ages, has become of extreme importance.

This study included 187 Pantaneiro horses bred in the Pantanal region of Mato Grosso, Brazil. They were clinically healthy and negative for infectious equine anemia after examination. The horses were reared in ranches and farms that furnished satisfactory nutritional and sanitary conditions. Feed management involved the use of native pastures consisting of Axonopus purpusii, Reimarochloa brasiliensis, Hymenachne amplexicaulis, Setaria geniculata, and Pontederia cordata and cultivated pastures of mainly Panicum maximum var. Tanzânia, Andropogon gayanus kunth, and Hyparrhenia rufa with water ad libitum. Those animals were kept in large-area pastures and were periodically submitted to sanitary management (e.g., worming, vaccination, and blood sampled for serological tests for infectious equine anemia) or kept in paddocks close to the center of the property, especially the pregnant mares, foals, stallions, and castrated males that were used in daily work and sport activities.

The horses were distributed into six experimental groups as follows: group I - 30 animals, males and females, aged up to eight months; group II - 30 males aged from nine to 24 months; group III - 28 females aged from nine to 24 months; group IV - 36 pregnant females; group V - 33 non-castrated adult males (stallions); group VI - 30 castrated adult males (geldings).

A single 10ml blood sample was collected from the animals after a routine physical examination to confirm their healthy state (Speirs, 1997). They were obtained from the jugular vein, using tubes with EDTA¹. A differential cell count was performed on slides of blood smears after staining - Diff-Quick® (Feldman et al., 2000).

Erythrocyte and leukocyte counts were carried out using a Neubauer chamber (SPEIRS, 1997). Hemoglobin concentration was determined by the cyanomethemoglobin method, with spectrophotometric readings at 540nm². Packed cell volume was determined by the microhematocrit method. RBC indexes, mean corpuscular volume (MCV), and mean corpuscular hemoglobin concentration (MCHC) were calculated according to standard formulas (Feldman et al., 2000).

The obtained values were submitted to statistical analysis using the SAS program (User’s , 1985), which determined the means, standard deviations, coefficients of variation, and extreme limits and performed an analysis of variance. Tukey’s test was employed at a level of significance of P<0.05 to compare the differences between the means.

Table 1 presents the results of the red blood cell count, packed cell volume, hemoglobin concentration, the RBC indices MCV and MCHC, leukocyte count, numbers of segmented neutrophils, band neutrophils, lymphocytes, eosinophils, monocytes and basophils. Because of the wide variation in the obtained values for eosinophils, monocytes, and basophils, the means and minimum and maximum values are listed in Table 1.

It was noted that at 25-months-old, values were lower for RBC count and PVC and higher for MCV in castrated horses (group VI) in comparison with the other groups, regardless of gender. Castrated horses (group VI) were employed in daily work and were maintained on the same nutritional regimen as the other groups, which suggests a possible nutritional deficiency and/or higher energy demand in this group of animals.

According to the findings described in the literature for other breeds, the obtained erythrocyte parameters were lower (Lumsden et al., 1980; Noronha et al., 2000). However, the present data are similar to the values described in sequential studies that showed a broad review of the published works, establishing reference values for hematological parameters for English Thoroughbred, Arabian, and Quarter-horse breeds, among others (Mullen and Hopes, 1979; Rose and Rodgson, 1994; Feldman et al., 2000).

The WBC and segmented neutrophils of foals younger than eight-month-old (Group I) showed higher values than those found in animals older than 25-month-old. WBC diminished as age advanced; however, gender had no influence. Some factors can be postulated as causes of such occurrence, among these, subclinical parasitism. The obtained WBC indexes were higher than those described in the literature for other breeds (Mullen and Hopes, 1979; Lumsden et al., 1980; Rose and Rodgson, 1994; Feldman et al., 2000). However, it should be noted that hematological parameters are influenced by various factors, including the time of sampling, diet, temperament of the horse, and conditioning and physical activities as well (Rose e Rodgson, 1994).

Under the imposed experimental conditions, it was noted that the mean values of the RBC indexes increased with age up to 24 months, and then declined. The values of the WBC indexes decreased as the animals became older. Gender did not influence on the examined parameters.

ACKNOWLEDGEMENTS

The authors express gratitude to the FAPEMAT (Fundação de Amparo à Pesquisa de Mato Grosso) for the financial support, and the ABCCP (Associação Brasileira de Criadores do Cavalo Pantaneiro), and the Hospital Veterinário da Universidade de Cuiabá (UNIC) for technical support.

Recebido em 28 de agosto de 2007

Aceito em 25 de fevereiro de 2008

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Publication Dates

• Publication in this collection
  12 June 2008
• Date of issue
  Apr 2008