The effects of sex and age on phytohaemagglutinin skin-testing of deer

Abstract

AIM: To determine if there are sex- or age-related differences in the increase in skinfold thickness in response to the mitogen phytohaemagglutinin (PHA) in red deer.

METHODS: One dose of 250 µg PHA was injected intradermally in the right side of the neck, and phosphate buffered saline (PBS) was injected at a second site as a control, in 110 (51 males and 59 females) captive Iberian red deer (Cervus elaphus hispanicus), ranging in age from 21 months to a5 years. Skinfold thicknesses were measured immediately before and 72 h following injection.

RESULTS: There was a significant effect of gender on the average increase in skinfold thickness; males had greater increases (8.8 (SEM 0.57) mm) than females (4.23 (SEM 0.39) mm) after correcting for other confounding variables. No age-related differences were evident, but differences between sexes were more marked with increasing age.

CONCLUSIONS AND CLINICAL RELEVANCE: Effects of gender, probably due to differences in energetic and reproductive constraints in red deer, should be taken into account when interpreting skinfold-test data, both in ecology and in the control of tuberculosis (Tb). Males tend to have a thicker skin than females, so skinfold increase relative to the thickness of the skin, rather than skinfold increase per se, should be used as a more appropriate measure of skinfold increase. This may also have clinical relevance in the interpretation of tuberculin skin testing.

KEY WORDS:

• Cellular immunity
• Cervus elaphus
• mammalian immune response
• wildlife bioindicators
• phytohaemagglutinin skin test

Acknowledgement

Funding was provided for this project by Fondo Europeo de Desarrollo Regional, Instituto de Investigación y Tecnología Agraria y Alimentaria (Grant RTA03-074); and Ministerio de Educación y Ciencia (Grant AGL2005-07401), Madrid, Spain. This study involved collaboration between the University of Castilla-La Mancha (foundation) and Grupo Santander-Fundación Marcelino Botín, Santander, Spain; and Y Fierro and the UCLM, Ciudad Real, Spain. We wish to thank the students and colleagues at Instituto de Investigación en Recursos Cinegéticos for their help with the laboratory and field work.