Introduction

Blood transfusion between human beings has been occurring since the XVII century; however, the safe use of this resource only became possible after the XX century (Hosgood 1990). The technological advancement allowed recent discoveries in transfusional therapy, such as the use of blood components and the control of transmissible diseases. There has been an increasing interest on this type of therapeutic modality in Veterinary Medicine; however, it is of utmost importance to maintain a quality standard when using this practice. There are few specialized hemotherapy services in Brazil. The importance of establishing blood donation programs that would benefit not only the receptor, but also the donor's sanity, minimizing the occurrence of short-and long-term adverse reactions is well known. In human Medicine, blood donation programs have been widely promoted and there is a constant concern about the donors' maintenance of health. In Veterinary Medicine, the transfusional practice appeared in the mid-50s (Hosgood 1990). The concept of blood donation in small animals is a relatively new one, which implies in the higher difficulty to find voluntary blood-donor dogs. Although there is a large number of animals that need blood components, the owners present a certain refractory attitude to the act of submitting their animals to blood donation. The following criteria are adopted at the program of blood donor dogs: the animals must weigh > 27 kg, have a docile disposition, age between 1 and 8 years (Schneider et al. 1995, Haldane et al. 2004) and negative results for the following diseases: Lyme, Ehrlichiosis, Dirofilariasis (Heartworm Disease), Brucellosis and Leishmaniosis (Lucas et al. 2004). They must also have undergone control for ectoparasites in addition to up-to-date vermifugation and vaccines. The maximum volume that a dog can donate without iron supplementation is 1618 mL/kg every 21 days (Abrams-Ogg 2000.). However, with iron supplementation, the dog can donate, on average, 22 mL/kg of blood every 21-28 days (Harrel et al. 1995).There are few studies related to the health monitoring of dogs that donate blood on a regular basis and the literature data on the hematological assessment is scarce. The regular physical examinations and blood assessment is one of the forms of control that seem to present good efficacy in evaluating possible interferences with the health of the donor animal. Thus, the objective of the present study was to monitor the erythrocyte parameters in dogs that donate blood every two months, through a complete blood count (CBC) every time the animal donated blood, with emphasis on hematocrit levels, for a period of 1 year.

Materials and Methods

The clinical and laboratory follow-up of 100 blood-donor dogs was carried out for a period of one year. The criteria adopted for the selection were: minimum body weight of 27 kg; age between 1 and 8 years; up-to-date vermifugation and vaccines; negative screening results for Ehrlichia canis, Dirofilaria immitis, Borrelia burgdorferi, Brucella canis and Leishmania sp. The animals did not present alterations at the physical examination. The blood was collected through the venepuncture of the jugular, after local asepsis. The donated blood volume was 450 mL for all dogs, regardless of the weight, every two months. The dogs were not sedated during the procedure. A control CBC was performed before the first donation and thereafter, the CBC were carried out every two months, according to the donations. The results were analyzed through the two-way Analysis of Variance (ANOVA), followed by Tukey's test.

Results

The donor dogs' age varied from 1 and 6 years. Most of the dogs belonged to the following breeds: Labrador, Doberman and Pit Bull. No significant variations were observed regarding hematocrit levels of the donor animals, for the one-year period (p = 0.10 FRIEDMAN, post-DUNN's test). There were no complications during the blood collection procedures.

Discussion and Conclusions

In our laboratory, the blood-donor dog program is established according to Abrams-Ogg et al. 2000. However, regarding the interval between donations and the volume of collected blood, for the benefit of the dogs' owners and lower levels of stress for the dogs, the donation occurs every two months and the volume collected is around 450 ml, regardless of the donor's weight without iron sulphate supplementation. Previous studies indicate the collection of approximately 16-18 ml (15-20% of the blood volume) of blood for each kilogram of weight of the donor. According to the formula: Estimated blood volume (liters) = 0.08-0.09 X Body weight (kg), an animal weighing 30 kg has a total blood volume of approximately 2.6L. The collected volume in our laboratory (450ml) comprehends approximately 16% of the total blood volume of the donor. It is known that a dog takes around 1 day to replace in circulation 1% of the circulation erythrocyte mass (Rebar et al. 2003), that is, the volume donated by each animal takes on average 16-21 days to be fully replaced by the body. This period of organic re-adaptation can vary from animal to animal and, therefore, the safety interval is increased between donations to one or two additional weeks, totaling an interval between donations that can vary from 21-28 days. Although the literature indicates this interval and volume for blood collection in a healthy dog, no studies have reported the long-term follow-up of blood donor dogs. In the present study, the follow-up of the erythrocyte levels of the animals that donate blood every 2 months for a period of one year, did not show any significant variations, thus indicating that blood donation, carried out according to the previously established criteria (Schneider et al.1995, Haldane et al. 2004, Lucas et al. 2004) and adapted in our laboratory, does not impair hematopoiesis.

References

1.  Hosgood G. 1990. Blood transfusion: A historical review. Journal American Veterinary Medical Association. 197: 998-1000.

2.  Schneider A. 1995. Blood components. The Veterinary Clinics of North America--Small Animal Practice. 25:1245-1261.

3.  Haldane S, Roberts J, Marks SL, Raffe M. R 2004. Transfusion medicine. Compendium of Continuing Education for the Practicing Veterinarian. 26:502-518.

4.  Lucas RL, Lentz KD, Hale AS. 2004. Collection and preparation of blood products. Clinical Techniques in Small Animal Practice. 19:55-62.

5.  Abrams-Ogg A. 2000. Practical blood transfusion, p. 263-307. In: Day MJ, Mackin A & Littlewood JD. BSAVA Manual of Canine and Feline Haematology and Transfusion Medicine. 1st ed. British Small Animal Veterinary Association, Quedgeley.

6.  Harrel KA, Kristensen AT. 1995. Canine transfusion reactions and their management. Veterinary Clinics of North America--Small Animal Practice. 25:1333-1364.

7.  Rebar HA, Macwilliams SP, Feldman FB, Metzger LF, Pollock HVR, Roche JA. 2002. Guide to Hematology in Dogs and Cats. 1st edition. Teton NewMedia. p. 39.