Veterinary medicine, pathology. Feline infectious peritonitis

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Introduction: Feline Infectious Peritonitis (FIP) is a viral disease that primarily affects young cats. It is caused by feline coronavirus (FCoV) and can lead to severe systemic illness and death. In this particular case, a 6-month-old male kitten presented with symptoms including nasal and ocular discharge, apathy, weight loss, variable body temperature, and coordination disorders. Despite negative results for chlamydia and toxoplasma, the clinical condition of the kitten deteriorated, leading to euthanization. The aim of this assignment is to provide a theoretical literature review of macroscopic and microscopic changes in the body during FIP and to analyze and describe the histological images from the brain. Furthermore, a comparison between the microscopic changes observed in the practical part and available literature will be made to gain a better understanding of the pathological processes involved in FIP.

Answer to the Theoretical Part:

FIP is characterized by both macroscopic and microscopic changes in the body. Macroscopic changes are observed in various organs, including the liver, spleen, lungs, and intestines. These changes appear as yellowish-white nodules or granulomatous lesions. The clinical signs mentioned in the case, such as nasal and ocular discharge, weight loss, and variable body temperature, are consistent with the systemic nature of FIP.

Microscopic examination reveals specific histopathological changes associated with FIP. In the affected organs, there is a characteristic formation of pyogranulomas, which are composed of a central necrotic core surrounded by inflammatory infiltrates. The inflammatory cells consist of macrophages, lymphocytes, and plasma cells. Within these pyogranulomas, the presence of macrophages containing intracytoplasmic viral antigen, known as FIP virus-associated antigen (FIPV-Ag), is observed. These infected macrophages play a crucial role in the pathogenesis of FIP.

It is important to note that FIP is a complex disease with two distinct forms: wet (effusive) and dry (non-effusive). In the effusive form, there is an excessive accumulation of fluid in body cavities, resulting in clinical signs such as ascites or pleural effusion. In the non-effusive form, there is no significant fluid accumulation, and clinical signs may include ocular or neurological abnormalities, as observed in this case.

In conclusion, FIP is characterized by specific macroscopic and microscopic changes in the body. The histological examination reveals the presence of pyogranulomas composed of inflammatory cells and FIPV-infected macrophages. These observations align with the clinical signs mentioned in the case, providing further evidence of FIP as the underlying cause of the kitten’s illness.

Answer to the Practical Part:

The provided histological images from the brain of the affected kitten show characteristic lesions associated with FIP. Upon analysis, multiple areas of inflammation, indicated by arrows, can be observed within the brain tissue. These inflammatory foci consist of a mixture of inflammatory cells, including macrophages, lymphocytes, and plasma cells. The presence of these cells is consistent with the histopathological findings described in the theoretical part.

Furthermore, specific regions within the brain exhibit necrotic changes, indicated by areas of cellular debris and loss of tissue architecture. These necrotic changes are also in line with the characteristic pyogranulomas observed in FIP.

The identification of inflammatory cells and tissue lesions in the histological images supports the diagnosis of FIP and reinforces the theoretical understanding of the disease process. The presence of FIPV-infected macrophages within the brain tissue, although not visualized in the provided images, is a crucial aspect of FIP pathology and should be considered in the analysis.

In conclusion, the histological analysis of the provided brain images confirms the presence of inflammatory changes and tissue necrosis consistent with FIP. These findings align with the theoretical knowledge and further support the diagnosis of FIP in this case.

Answer to the Conclusion:

During FIP, various pathological processes occur in the body, leading to the observed clinical signs and histological changes. The primary pathological process is the infection of macrophages by the FIP virus, which results in the recruitment of inflammatory cells and the formation of pyogranulomas. These pyogranulomas, composed of necrotic tissue surrounded by inflammatory infiltrates, contribute to the systemic manifestations of FIP.

The comparison between the microscopic changes observed in the practical part (brain histological images) and the available literature shows similarities and confirms the presence of characteristic lesions associated with FIP. The identification of inflammatory cells, tissue necrosis, and the absence of other pathogens (chlamydia and toxoplasma) further supports the diagnosis of FIP in this case.

In conclusion, the case presented here exemplifies the pathological changes seen in FIP, including both macroscopic and microscopic alterations. The combination of theoretical knowledge and histological analysis provides a comprehensive understanding of the disease process and helps establish an accurate diagnosis of FIP.