Paratuberculosis in sheep and goats: Pathogenesis, diagnostic findings, and control strategies

Paratuberculosis (PTB), also known as Johne's disease, is a chronic contagious granulomatous disease of a wide variety of animals. It is caused by Mycobacterium avium subsp. paratuberculosis. This review summarizes the pathogenesis, clinical, hematobiochemical, sonographic, pathologic findings, and approaches to treatment and control of PTB in sheep and goats. Decreased appetite, weight loss, and changed fecal consistency were reported in sheep and goats with PTB. Clinical disease in sheep and goats is generally observed in those 2-4 years old. Other findings may include anorexia, coat roughness, and depression. The recorded hematological changes included neutropenia, leukocytosis, erythrocytosis, and increased hematocrit percent and hemoglobin concentration. Serum changes included hypocalcemia, hypoalbuminemia, hypomagnesemia, hypoproteinemia, and increased activity of creatine kinase. An overall increase in the intestinal mucosa thickness was detected on sonography in goats with PTB. Corrugation and folding of the intestinal mucosa may be also imaged in goats with PTB. However, the remarkable enlargement of the mesenteric lymph nodes is the most important finding. In sheep, postmortem findings included thickened intestinal walls, folding and corrugation of intestinal mucosa especially close to the ileocecal junction. Edematous and enlarged ileocecal and mesenteric lymph nodes may be observed. In goats, necropsy findings included enlargement of the mesenteric lymph nodes and thickened walls of the small intestines with folded and corrugated mucosa. No successful therapy of PTB in sheep and goats has been reported. The control of PTB in sheep and goats can be achieved by vaccination. In conclusion, early detection and eradication programs of PTB should be implemented more effectively for the control of PTB in sheep and goats. More research should be directed toward a vaccination program of PTB in these species.