Clinical Mastitis in Small Ruminants Referred to a Veterinary Teaching Hospital: 23 Cases

Abstract

Clinical mastitis in small ruminants is usually seen with an incidence of less than 5% and most cases, especially with hyperacute evolution, are not referred for hospital care. During the 5-year survey, 16 goats and 7 sheep, totaling 23 small ruminants, met the inclusion criteria with a definitive diagnosis of clinical mastitis. Clinical signs ranged greatly among cases, varying from septic state in hyperacute cases, and enlarged, pendulous udder associated with chronic pain and abnormal gait in chronic cases. Microbiological culture revealed a wide array of bacterial pathogens, including Staphylococcus aureus, Escherichia coli, Streptococcus spp., and Pasteurella spp. In vitro antimicrobial susceptibility profiles varied greatly among bacteria isolates, ranging from sensitive to all tested antimicrobials to a multi-resistant profile. Pathological features included hyperemia and dark red areas of necrosis in the skin, marked hyperemia of the affected gland at the cut surface, lactiferous ducts and gland cisterns filled by cloudy or suppurative fluid, abscesses, and hardness of the mammary gland parenchyma. This retrospective study highlights the multifactorial nature and clinical variability of mastitis in small ruminants, demonstrating its significant impact on animal health, welfare, and production.

Keywords: goat; intramammary infection; mastectomy; sheep; systemic disturbances.

Figure 1

Clinical aspects of the affected mammary glands of small ruminants with mastitis. (A) Goat. Redness and red-black areas in the skin of the teat and udder. (B) Goat. Asymmetry of the udder due to unilateral enlargement of the left gland.

Figure 2

Gross pathological alterations in the mammary tissues of small ruminants with mastitis. (A) Goat. Hyperemia in the skin of the udder and a dark area of necrosis affecting the teat. (B) Goat. Marked hyperemia of the affected parenchyma. (C) Sheep. Lactiferous sinus filled with a white-cloudy inflammatory fluid. (D) Sheep. An abscess within the parenchyma close to the teat cistern.

Figure 3

Histological findings in the mammary tissues of small ruminants with mastitis. (A) Goat. Marked hyperemia of interstitial vessels in the mammary lobes and inflammatory infiltrate filling alveoli (H&E, bar = 250 μm). (B) Goat. Alveolar epithelial degeneration, necrosis, and numerous neutrophils fill alveoli (H&E, bar = 50 μm). (C) Sheep. Interstitial mononuclear inflammatory infiltrate within mammary lobes (H&E, bar = 100 μm). (D) Severe lymphocytic inflammatory infiltration surrounding mammary alveoli (H&E, bar = 25 μm).