Medicinal plants used for traditional veterinary in the Sierras de Córdoba (Argentina): An ethnobotanical comparison with human medicinal uses

This study was based on the peasant population of the hills and intermontane valleys of the regions of Calamuchita and Paravachasca (Santa María and Calamuchita Departments) and complemented with surveys carried out in settlements near the town of La Calera, all in the area of the Sierras de Córdoba in Central Argentina, located to the southwest and west of the capital city of Córdoba (Figure 1).

Today, the population of the area is highly heterogeneous, as different groups have settled there. "Criollo" peasants now live side-by-side with immigrants from the last century, as well as city dwellers who have come from Córdoba city and other urban centres. As in other places in Central Argentina the local "Criollo" culture arose as an heritage combination of aborigines and Spaniards or their descendants, after the conquest and foundation of the city of Córdoba in 1573 following a strong Jesuit influence. Between the 19^th and 20th Centuries, the European influence, mainly Spanish and Italian, was reinforced as a consequence of the immigration waves. As a consecuence of this historical process, traditional indigenous knowledge, still relative to medicine was practically invisibilized, if not extinct, remaining almost vestigial in their contributions to the current local peasant culture. This study was particularly performed with the native population of farmers and livestock, mainly goat and cattle smallholders. Depending on the economy of the households, cows and horses, mainly, and also goats, sheeps and dogs, receive attention and are treated by traditional veterinary medicine. Although in recent decades become in a progressive depeasantization process, their main economical income are still based on activities such as breeding and selling cattle, tourism-linked services (like horse rental, selling regional products, medicinal herbs, sausages and cheese); recently, in many cases they are also wage earners. Due to environmental shrinkage (related to the advance of monoculture, increasing urbanization, bush fires and loss of native forests), the availability and thus the reliance on the use of plant resources has been significantly reduced among the native local people. The multiple origin of their knowledge, a synthesis between vestigious indigenous lore and European beliefs (traced back to the time of the Spanish Conquest in the 16th Century and reinforced by European immigrants in the last two centuries), explains the similarity to folk medicine found in other Argentinean regions, and the likeness of features found in the traditional Hispanic-European medicine. Also, previous ethnobotanical studies in human medicine carried out in this region describe the validity and entrenchment of traditional healings and folk medicine, mentioning the use of more than 190 medicinal species, most of them natives [17, 21].

The climate in the region is mainly semi-humid in summer with maximum temperatures ranging between 28-36°C, and semi-dry in winter with minimum temperatures of 8-14°C. The annual rainfall varies between 700-900 mm with values decreasing to the west and increasing with altitude [22]. The flora comprises the 'Espinal' province and the 'Chaco Serrano' district belonging to the 'Chaco' province, with vegetation alternating between xerophytic plants, shrubs and high pastures. The most frequently found plants are Prosopis alba, Prosopis nigra, Aspidosperma quebracho-blanco, Celtis tala, Celtis iguanaea, Acacia caven, Geoffraea decorticans, Lithraea molleoides, Zanthoxylum coco, Kageneckia lanceolata. Among the aromatic and medicinal shrubs, there is a predominance of Lippia turbinata, Aloysia gratissima, Mintosthacys mollis, Baccharis crispa and Baccharis articulata [23, 24].

Fieldwork was carried out as part of an ethnobotanic regional study in which 64 informants (35 women and 29 men) were interviewed about medicinal plants used in veterinary medicine during 2001-2004, 2006 and 2010. The age of the informants ranged from 26 to 88 (X = 61.6 ± 12.8 years). Based on techniques commonly used in ethnobiology and ethnography -as participant observation and open and semi-structured interviews- [25, 26], we obtained information on the traditional practices of diagnosis and healing, focusing on the veterinary uses given to plants (part of the plant used, method of preparation and administration, etc.). Interviews were recorded on tapes and registered in field notebooks. Plants speciemens were collected in the company of the informants and their vernacular names were registered. They were then identified by the authors, and herbarium specimens were deposited in the herbarium of the Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba under the acronym ACOR, and in the herbarium of the Botanical Museum (IMBIV), acronym CORD. All the information was systematized in a database of medicinal plants which comprises medicinal uses in human diseases obtained in a larger ethnobotanical study developed in the region. Over 45 hours of taped records are deposited at the first author's address. Before being interviewed the peasants were briefed on the research project and its academic objectives. Conversations with specialists and inhabitants were based on a common objective: to increase knowledge regarding natural remedies and develop educational materials of local interest, as suggested in the guidelines of the International Society of Ethnobiology Code of Ethics [27].

Non-parametric statistic was used to evaluate differences in medicinal plant knowledge, use, and valorization by local people using INFOSTAT software [28]. U-Mann Whitney and Kruskal-Wallis tests were used to compare differences between gender and occupation of the informants, respectively (p < 0.05). The Spearman rank correlation was used to analyze medicinal plant knowledge and uses in relation to age (p < 0.05). These tests were the most appropriate because the data did not have normal distribution. A comparison between traditional veterinary medicine and previous human medicine studies developed in the region [17, 21] was performed by analyzing the percentages of common species and uses, and by considering Sorensen's Similarity Index.

Regarding ethnobotanical knowledge, 42 informants (65% from a total of 64) knew at least one application in veterinary medicine. An average of 2,95 ± 4,16 (Mean ± S.D.) medicinal uses were mentioned (with a maximum of 20 uses per informant), or 4.97 ± 4.37 when only considering people who cited at least one medicinal use. These highly reduced and variable values in the amount of medicinal uses, especially compared to those mentioned for human medicine as stated ahead, evidence a heterogenous knowledge restricted to certain informers. There are significant differences in the number of uses mentioned between genders (Table 1), with a greater number of applications mentioned by men (Mann-Whitney test, p < 0.05). This table also shows that there are significant differences in the knowledge of medicinal plants according to the occupation of the interviewees (Kruskal-Wallis test, p = 0.01), with most uses described by cattle breeders, followed by livestock workers and healers. This shows that veterinary ethnomedicine knowledge is strictly related to people working with livestick in first place, and to a second degree to healing practices, which in many cases do not only use plants but also symbolic-ritualistic practices like "curing by word" or "by footprints", as described in more detail below. However, most of the interviewed healers were specialized in human medicine, and although some did specialize in animals, very few treated both humans and animals.

There is no correlation between the total number of medicinal plants known and used by the informants and their age (Spearman correlation test, r = -0.03, p > 0.5). It is noticeable that, unlike what is usually evidenced in ethnobotanical studies, veterinary knowledge is not restricted to or more relevant in elderly people in this study area. However, in this case it was found to be restricted to people specialized in livestock.

A total of 127 medicinal uses corresponding to 70 plant species with veterinary importance belonging to 39 botanical families were gathered and documented in this research.

Table 2 lists the plant species in alphabetical order according to their Latin name. Each plant is presented with its corresponding botanical identity, herbarium sample number, local name, and medical applications, indicating the part used, form of preparation and mode of administration, Specific uses or recipes are indicate in cases where the application is referred to a particular type of animal. Finally, it details identical or similar uses in traditional human medicine recorded in the same region.

From a botanical point of view, the species used in veterinary medicine are mostly represented by shrubs, subshrubs and herbaceous species; trees creepers and non vascular forms are less frequent (Figure 2). The use of native wild species is relevant in most cases, as well as the use of some wild introduced species, and both categories surpass the use of cultivated plants. This, together with the wide range of uses given to the native flora of the area, reveals the excellent knowledge and integration peasants have of their surroundings, as well as their great capacity to satisfy their own therapeutic requirements using local plant resources.

The Asteraceae family is the most commonly used and species-rich family in this study and also the most representative in the medicinal flora of the Province of Cordoba [29]. It is followed by Lamiaceae (by their number of species), and Malvaceae, Solanaceae, Zygophyllaceae, Rutaceae and Verbenaceae (according to their number of uses and species) (Figure 3). Considering the ratio between the number of uses and number of species (N° uses/N° sp.), the Aquifoliaceae and Lythraceae families head the list with Ilex paraguariensis and Heimia salicifolia, respectively. As in other human ethnomedicine studies we carried out in the region, a significant proportion of these medicinal species are aromatic, especially those belonging to the Lamiaceae, Rutaceae and Verbenaceae families, or have known active substances, as in the case of Solanaceae [18‐20]. Moreover, according to Moerman et al. [30], Asteracaeae, Lamiaceae, Malvaceae and Solanaceae are some of the most intensely used families for human medicine in different regions of the world. The results obtained in this regional study, would allow extending Moerman's hypothesis of an existence of a global pattern of human knowledge and selection of medicinal plants to the field of veterinary medicine.

Among the species with the greatest number of medical applications we find "contrayerba" (Trixis divaricata ssp. discolor) with six applications; "duraznillo" (Cestrum parqui), "quiebrarado" (Heimia salicifolia), "yerba mate" (Ilex paraguariensis), "jarilla" (Larrea divaricata), "poleo" (Lippia turbinata), "malva" (Malva parviflora, Malva sylvestris), "tabaco" (Nicotiana tabacum), "llantén" (Plantago major) and "ruda" (Ruta chalepensis), each of which have four applications; and finally "ajo" (Allium sativum) and "altamisa" (Tanacetum parthenium) with three different uses.

Based on the consensus of the interviewed subjects, the following applications were the most popular: the use of "ligas" (Ligaria cuneifolia and Tripodanthus flagellaris) for treating placental retention, the use of "polvillo del diablo" (Calvatia cyathiformis and probably other undocumented Gasteromycetes) and "espinillo" (Acacia caven) for healing wounds and sores and the symbolical application of "maíz" (Zea mays) for treating animal distemper.

Although this study is not part of a research program on bioactive compounds, there are phytochemical references on some of the plants listed in this article, especially in those with greater consensus of use or with major number of medicinal uses. For example, Calvatia cyathiformis has been reported as a good edible species in Britain, North America and Nigeria; in human medicine it is often used as a haemostatic and is also known to inhibit the formation of tumours [31]. Furthermore, pharmaceutical research has led to the isolation of several steroids from these fungi [32‐34]. Antiproliferation, inmunomodulator activity and induction of apoptosis has been described for Ligaria cuneifolia [35, 36]. Although its oxytoxic effects have not been corroborated, it could be related to its high concentration of tyramine that induces toxicity and high blood pressure [37]. The use of Acacia caven as an antiseptic, cicatrizant and vulnerary has been described in different ethnomedical studies and a great variety of known active components and substances have been identified in this species [38, 39]. However, to the present day studies on its biological activity have only corroborated its effects on a few fungi [40]. Likewise, as mentioned in the review of Goleniowski et al. [40], biological activity has been detected in extracts from plants with less consensus of use among the inhabitants, but that are used in traditional recipes. For example, antibiotic activity has been described for Aloysia gratissima and Lippia turbinata (used for treating wounds and sores), antifungal activity has been mentioned for Conyza bonariensis (used in cases of diarrhoea), and anticancer and antibiotic activity have been described for Larrea divaricata.

Regarding the number of species used for differents medicinal applications (Table 3), the most relevant are those used as cicatrizants (for treating wounds and injuries; sores and ulcers; mastitis, and others) followed by plants used for digestive disorders, ostheomuscular disorders and parasitosis.

The commonest ways of preparing veterinary plant formulations are decoctions and infusions in water (62%), followed by macerations (6%), direct application (5%) and smoke baths (4%). In general, the whole plants or some of the aerial parts are used (71%). Most preparations are administered externally (60%), either in washes, compresses or by friction, while concoctions for internal use, such as drinks and inhalations, are used to a lesser extent (40%). This contrasts with the most common forms of administration in human medicine for the same study area and population, where 80% of the preparations are for internal use in forms of infusion and decoctions [17, 21].

Regarding the plant parts used (Table 4), peasants usually harvest the aerial parts (42% of the cases, 34 spp.) or leaves (27.7% uses, 17 spp.), followed by roots (6.3% uses, 4 spp.) and whole plants (5.4% uses, 4 spp.), which entails a mild to moderate impact on the conservation of these resources. In general, the inhabitants only use the aerial parts of native medicinal species like Minthostachys verticillata, Trixis divaricata subsp. discolor, Baccharis crispa and Equisetum giganteum that are prioritized for conservation according to a study conducted at regional level [41], using the roots only in a few special cases (T. divaricata). Furthermore, in some cases (Minthostachys verticillata, for example) the local people take particular care when harvesting specimens.

In addition to the aforementioned plants, many other preparations, concotions and applications involving the most varied ingredients are also used for therapeutic practices. These are described in Table 5, together with a list of ailments (with their vernacular names) that afflict the animals.

An important topic in animal health is the presence of toxic plants. Furthermore, it is also particularly interesting for the discovery of new bioactive natural products [42]. Veterinarians generally believe that intoxication of livestock by consumption is a significant problem in the region, especially for cattle coming from other places. Local animals are also affected, but only in times drought and subsequent shortage of pastures during spring regrowth, or in cases of overgrazing. Likewise, cases of intoxication by the consumption of buds, particularly of "duraznillo" (Cestrum parqui), may occur when animals seek shelters or remain in enclosures during prolonged rainy periods. While references on this topic give account of more than a hundred potentially toxic plants in Argentina [43], only a dozen were reported by the local people and documented in this paper. The plants were categorized by the informers according to the frequency of intoxication as follows:

When diagnosing an animal's health the inhabitants consider their "countenance", particularly when they appear sad or have drooping ears, symptoms that usually indicate illness. A characteristic trait of traditional veterinary therapy is the inclusion of biomedical concepts, humoral or Hippocratic notions and traditional Spanish medical features in its explanation. There are a diversity of criteria associated with different etiologies assigned to the affections of animals that regulate the prescription of remedies. Thus, bleedings and incisions used for treating distemper are practices historically related to Hippocratic-Galenic or humoral medicine, based on the notion of the regulation of body fluids. Similarly, diseases originated by an imbalance due to excessive heat or cold are treated with plants from the opposite category, in other words cold or hot plants, to re-establish the balance. Although references to this therapeutic criterion for animal diseases are not as frequent as for humans, the explanations indicate that the Hippocratic opposite principle is a still valid in traditional veterinary therapy. For example, loss of blood from a castration predisposes animals to getting "cold" with the consequent risk of the animal suffering from "pasmo"; hence, the prescribed treatments are based on rubdowns with oil, ashes, kerosene, and other "hot" ingredients. Likewise, plants like "peperina" (Minthostachys verticillata), "contrayerba" (Trixis divaricata ssp. discolor) and "ruda" (Ruta chalepensis) are considered "hot" remedies. Some historical aspects of these principles, together with a detailed analysis of this therapeutic criterion in the traditional medicine of Argentina, particularly in Córdoba, can be found in other studies carried out by our group [16, 19‐21, 44] and other authors [45‐49].

As described for popular Spanish medicine [50], and observing its influence in Criollo veterinary medicine, the inhabitants of this area also involve Christian symbolism in their therapies, as in the case of applications or incisions made in the shape of a cross to cure eye or digestive affections. In addition to the wide range of plant pharmacopoeia and popular remedies mentioned above, traditional therapies include religious-ritualistic practices involving prayers, formulas and representations regarding planetary influence and other notions, mostly inherited from traditional Hispanic-Christian medicine. In this sense, the inhabitants assiduously use the following types of treatments:

Several authors claim that ethnomedical practices are largely the same for animals and people, whether in the form of administration of the materia medica, in the materials themselves, or in surgical, mechanical, behavioural, or medical religious practices [2, 10, 15, 51]. Schillhorn van Veen [51], in an historical and current analysis based on the similarities of both types of medicines, suggested the convenience and application of a broader one-medicine concept integrating animal and human medicines, and the need, in a contemporary context, of a more responsive, safe and effective healthcare system that responds to social changes such as the interest in non-conventional medicines. In general terms, and in accordance with these studies, almost all the plants and some of the medicinal applications used for traditional veterinary practices in the "sierras de Córdoba" have also been described in the local popular human medicine, revealing a remarkable similarity. In fact, and regarding the plant parts used and ways of application, there are not many differences between human and animal therapies [15, 17, 52]. Also, most of the species with the greatest number of medical applications in traditional veterinary medicine (Trixis divaricata ssp. discolor; Larrea divaricata, Malva parviflora, Malva sylvestris, Plantago major, Ruta chalepensis and Tanacetum parthenium) coincide with the twenty species with the greatest number of uses in human medicine [17, 21].

A deeper analysis, as shown in Table 6, shows that although the veterinary medicine seems a subset of the human medicine, it presents certain distinct features. This is evident when regarding the number of medicinal taxons involved. Although almost all the species used (98.6%) in veterinary medicine are part of the domestic human ethomedicine, the values of the similarity index (S = 0.53) reveal a group of species that are only used in human medicine (probably because it involves a wider spectrum of affections that are irrelevent in animals). This difference increases when considering the number of medicinal uses with only 45.7% common uses, while the rest are exclusively used for treating of animal affections (especially in cases which have no correspondance with human affections such as myasis, udder infection, "tasca"). The first analysis evidences a considereable difference in the medicinal plant corp, which becomes still more evident considering the low value of the index of similarity of uses (S = 0.13). This allows us to hypothesize that the applications in veterinary medicine were originated based on the human medical ethnobotany, followed by particular applications tested specifically for this ambit. These tests required selecting part of the available plant biodiversity, and used it in the quest of applications destined specifically to animal affections.