Hair is one widely used alternative matrix for endocrine studies. Not only can it maintain hormone content during storage for long periods of time, but its collection also induces little to no stress. Noninvasive techniques have broadened the opportunities for endocrine research, particularly regarding wild animals. Despite its advantages, many sources of variation may affect the steroid concentration found in hair, such as body location harvested, fur color, reproductive status, and sex. Thus, domestic species, such as the dog, are an excellent and approachable model for understanding this variability. For such, we addressed diverse sources of variation in testosterone concentrations from 24 domestic dogs (Canis lupus familiaris) of the Poodle breed of various colors and neuter status, and from both sexes. The variation comprised the comparison between 2 different matrices (blood vs hair); 2 different extraction storage methods (refrigerator vs freezer); 3 body regions (head, torso, and limbs); 3 coat colors (black, brown, and white); different neuter status (intact vs castrated males) and, finally, sex. Our results showed no correlation between blood and hair testosterone concentrations. Additionally, we did not find differences related to the storage method, body region, or coat color. There were differences in concentration between males and females, but not between females and castrated males. We discuss hair testosterone levels exhibited reasonable stability, and we present practical applications for both domestic and wildlife animals.

头发是用于内分泌研究的一种广泛使用的替代基质。它不仅可以在长时间存储期间保持激素含量，而且其收集也几乎不引起压力。非侵入性技术扩大了内分泌研究的机会，尤其是在野生动物方面。尽管有其优点，但许多变异来源可能会影响头发中类固醇的浓度，例如收获的身体部位，毛皮的颜色，生殖状况和性别。因此，诸如狗之类的家养动物是理解这种变异性的极佳且易于接近的模型。为此，我们研究了24只家犬（Canis lupus friendlyis）睾丸激素浓度变化的多种来源）两种颜色和中性状态的贵宾犬品种，并且来自两性。变化包括2种不同矩阵（血液与头发）之间的比较。2种不同的提取存储方法（冰箱与冰柜）；3个身体部位（头部，躯干和四肢）；3种外套颜色（黑色，棕色和白色）；不同的中性状态（完整男性与cast割男性）以及最终的性别。我们的结果显示血液和头发的睾丸激素浓度之间没有相关性。此外，我们没有发现与储存方法，身体部位或肤色有关的差异。男性和女性之间的集中度有所不同，但是女性和cast割的男性之间没有差异。我们讨论毛发睾丸激素水平表现出合理的稳定性，并且我们为家畜和野生动物提供实际应用。