Читать книгу Animal Behavior for Shelter Veterinarians and Staff - Группа авторов - Страница 126

The nervous system of the gastrointestinal (GI) tract and the central nervous system are linked in a bidirectional manner by the sympathetic and parasympathetic pathways, resulting in what is referred to as the brain–gut axis. Due to this interrelationship, chronic stress can have profound effects on the enteric nervous system (ENS). Severe life stressors have been associated with several GI tract conditions in humans (Bhatia and Tandon 2005), and the effects in animals are just now being explored. Chronic stress has been demonstrated to decrease gastric emptying, increase intestinal contractility, increase gut permeability, reduce water absorption in the gut, disrupt normal electrolyte absorption, and increase the colonic inflammatory response (Bhatia and Tandon 2005). Many gastrointestinal conditions such as chronic diarrhea and vomiting may be closely associated with stress. However, when presented with an animal with GI signs, the possibility of internal parasites and infectious organisms must also be ruled out. Newer polymerase chain reaction (PCR) tests can be helpful in ruling out some of these conditions. It is important to always keep in mind that nothing precludes an animal from having GI distress from multiple etiologies; therefore, both infectious causes and stress may need to be addressed.

Disruptions in the microbiome have been shown to play a role in anxiety and depression in many species (Foster and Neufeld 2013). In addition, studies in laboratory animals have shown that when young developing animals do not have normal gut microbiomes, they develop an exaggerated stress response and a dysregulated HPA axis (Sudo et al. 2004). Minimal work has been done on the role of the gut microbiome on behavior in dogs, but some limited research suggests that dogs demonstrating aggressive behavior may have distinctly different populations of gut bacteria compared to dogs that do not show aggression (Kirchoff et al. 2019; Mondo et al. 2020). More research is needed to identify what constitutes a healthy gut microbiome and how to adjust an “unhealthy” gut before we can apply what we have learned to companion animal care. Once again, the impact of stress on normal development and general health is clear and reminds us that it must not be overlooked.

Behavioral signs that may be associated with gastrointestinal disease include polyphagia, hyperphagia, polydipsia, coprophagia, and grass and plant eating. Oral behaviors such as frequent licking of surfaces (not self‐licking), sucking, pica, gulping, and lip‐smacking behaviors may all be associated with gastrointestinal disorders. However, some partial motor seizures may also be associated with similar behaviors. Many gastrointestinal disorders can manifest with unusual behavioral signs. In one recent study where 19 dogs were examined due to frequent surface‐licking behaviors, 14 of the dogs were determined to have some form of gastrointestinal disease (Bécuwe‐Bonnet et al. 2012). These included conditions such as delayed gastric emptying, irritable bowel syndrome, gastric foreign body, pancreatitis, and giardiasis, to name a few. The unusual behavior of fly biting, considered by some to be a compulsive disorder, has even been found to be associated with gastrointestinal conditions such as gastroesophageal reflux (Frank et al. 2012).