Guinea pigs were introduced to Europe from South America and were originally used as experimental animals and later as pets. Guinea pigs are exclusive herbivores whose diet is based on plant food origin with a high fiber content. The guinea pig caecum is the primary site of fermentation in which vitamin B and essential amino acids are synthesized with the help of microorganisms. Coprophagy enables the intake of vitamin B and optimized protein utilization. The aim of this study was to describe the current knowledge of guinea pigs diet, an overview of pathological conditions caused by feeding errors and the prevention of their occurrence. Vitamin C is essential for this species and deficiency of vitamin C manifests as scurvy. In addition to hypovitaminosis C, meal composition plays an important role in the prevention of other diseases and pathological conditions such as malocclusion, cecal impaction, bloat, pregnancy toxemia, tooth abscess and soft tissue calcification. Proper nutrition in the treatment of certain pathologies is also important. Anorexic guinea pig is always considered an emergency case and such individuals should be force-fed with specially designed mixtures to preserve digestion and prevent gut dysbiosis. As the physiological gut microflora is extremely sensitive to changes, it is always important to use safe antibiotics for treatment to avoid enterotoxemia with a potential lethal outcome.