A dog at the keyboard: using arbitrary signs to communicate requests

As a consequence of domestication, dogs have a special readiness for communication with humans. We here investigate whether a dog might be able to acquire and consistently produce a set of arbitrary signs in her communication with humans, as was demonstrated in ""linguistic"" individuals of several species. A female mongrel dog was submitted to a training schedule in which, after basic command training and after acquiring the verbal labels of rewarding objects or activities, she learned to ask for such objects or activities by selecting lexigrams and pressing keys on a keyboard. Systematic records taken during spontaneous interaction with one of the experimenters showed that lexigrams were used in an appropriate, intentional way, in accordance with the immediate motivational context. The dog only utilized the keyboard in the experimenter`s presence and gazed to him more frequently after key pressing than before, an indication that lexigram use did have communicative content. Results suggest that dogs may be able to learn a conventional system of signs associated to specific objects and activities, functionally analogous to spontaneous soliciting behaviors and point to the potential fruitfulness of the keyboard/lexigram procedure for studying dog communication and cognition. This is the first report to systematically analyze the learning of arbitrary sign production in dogs.

Two-Item Sentence Comprehension by a Dog (Canis familiaris)

Syntax use by non-human animals remains a controversial issue. We present here evidence that a dog may respond to verbal requests composed of two independent terms, one referring to an object and the other to an action to be performed relative to the object. A female mongrel dog, Sofia, was initially trained to respond to action (point and fetch) and object (ball, key, stick, bottle and bear) terms which were then presented as simultaneous, combinatorial requests (e. g. ball fetch, stick point). Sofia successfully responded to object-action requests presented as single sentences, and was able to flexibly generalize her performance across different contexts. These results provide empirical evidence that dogs are able to extract the information contained in complex messages and to integrate it in directed performance, an ability which is shared with other linguistically trained animals and may represent a forerunner of syntactic functioning.

Ultrastructural changes in the ovary cells of engorged Rhipicephalus sanguineus female ticks treated with esters of ricinoleic acid from castor oil (Ricinus communis)

Rhipicephalus sanguineus is a widely distributed tick species that has adapted to the urban environment, and the dog is its main host. This species is also known as a vector and reservoir of diseases caused by bacteria, protozoa, and viruses. Currently, acaricides of synthetic chemical origin have been widely and indiscriminately used, leading to the development of resistance to these products by ticks and causing damage to the environment. Thus, these issues have made it necessary to seek other forms of controlling these ectoparasites. R. sanguineus was artificially infested in host New Zealand White rabbits, which were divided into four treatment groups: control (CG1 and CG2) and treatment (TG1 and TG2) groups. TG1 and TG2 hosts were provided with feed supplemented with esters of ricinoleic acid from castor oil at a concentration of 5 g/kg of feed for 7 and 15 days. Afterward, the ovaries of the female ticks were removed for analysis by transmission electron microscopy. The results showed ultrastructural changes in the somatic and germ cells of ovaries from TG1 and TG2 females, particularly with respect to chorion deposition, a protective membrane of the oocyte, as well as in the transport process of vitellogenic materials via the hemolymph and pedicel cells. Moreover, the mitochondria were less electron-dense and had cristae that were more disorganized than the mitochondria from CG1 and CG2 individuals. Thus, this study demonstrated the action of esters on the ovaries of R. sanguineus, signaling the prospect of a way to control this ectoparasite without affecting nontarget organisms or the environment. Microsc. Res. Tech., 2012. (c) 2011 Wiley Periodicals, Inc.