The learning process for an adequate implementation of new procedures includes the translation of the clinical knowledge to the use of novel technologies. One of my favorite activities during the visit to the Dairy Farm, is the inspection on the udder structures through ultrasonography. Ultrasonography procedures can support the diagnosis of udder infections and gland abnormalities that were detected at the milking parlor and help to address these disorders with appropriate treatment approaches, considering the information regarding the extension of the damage that imaging can provide.
In the dairy cow, ultrasonography of a healthy udder reveals a parenchyma that is homogeneous with a granular appearance (1) given by the lactiferous alveoli, connective tissue, and myoepithelial cells, together with the visualization of milk ducts and blood vessels. Moving down toward the base of the teat we should visualize the gland cistern, characterized by anechoic and large lactiferous ducts divided by several echogenic septa of connective tissue.
To get started, I suggest looking for cows without history of mastitis in a way that I can assess the above definition of a normal ultrasonography of the mammary gland. In figure 1a, the uniform parenchyma demonstrates no echogenic changes compatible with physical trauma nor infection in the gland. Also, small lactiferous ducts were visualized. Figure 1b presents a visual inspection of the gland cistern, about 2 inches up from the teat base. Here, echogenic and uniform structures surrounding the cisterns with some anechoic milk volume were observed. In addition to the images, palpation and clinical inspection of the udder and milk did not show alterations, so ultrasonography supported and provided more information to make me more confident that this cow had a healthy udder.
Figure 1. Sonogram of the udder obtained with the Easi-Scan ultrasound system. A) Longitudinal section of a healthy mammary gland taken on the left-rear quarter at approximately 12 inches proximal to the base of the teat. Granular and uniform parenchyma was visualized, together with lactiferous ducts (withe arrow) and skin and connective tissue (red arrow). B) Transversal section of a healthy gland cistern with the white arrow showing connective tissue septa dividing the cisterns (red arrow).
Now, let’s turn over to a cow diagnosed with mastitis by examination of the milk at the milking parlor. Here I start with a visual inspection of the quarter checking signs of inflammation (redness, heat, swelling, and pain). The right-rear quarter appeared slightly enlarged and during milk inspection some flakes were evident. There were no signs of pain or heat at palpation. For the ultrasound assessment, I focused on the same points described in figure 1. The imaging findings on the quarter clinically diagnosed with mastitis included enlarged blood vessels and lactiferous ducts (Figure 2a), together with heterogeneous parenchyma characterized by hyperechoic spots surrounding blood vessel or lactiferous ducts (Figure 2b) which may correspond to cell infiltration, pus, or gas formation (1).
Figure 2. Longitudinal section of the right-rear quarter clinically diagnosed with mastitis. A) White arrows show dilatation of blood vessels or lactiferous duct because of the inflammatory response. B) White arrows show non-uniform parenchyma with hyperechoic spots.
A good practice in the examination of mastitis through ultrasonography is to perform a mirror evaluation on the same ultrasound points in the other quarters. The udder is supported by a complex system of suspensory ligaments that separates the left and right halves of the udder and a thin membrane that separates front and rear quarters (1), which keeps quarter parenchyma isolated from each other. Figure 3 shows imaging of the left-rear quarter compatible with the definition of a normal glandular parenchyma.
Figure 3. Longitudinal section of the left-rear quarter. Homogeneous granular parenchyma was visualized; no enlarged blood vessels or lactiferous ducts were detected.
The use of ultrasonography may support not only the diagnosis of mastitis (1, 4) but also of respiratory (2) and digestive (3) diseases. A valuable point of the ultrasound images for the evaluation of the mammary gland is the estimation of the severity of the damage in the tissue evidenced by the presence of fibrosis into the gland parenchyma, the gland cistern, and the teat, pus spots and the enlargement of the lactiferous ducts.
(1) Franz S., M. Floek and M. Hofman-Parisot. 2009. Ultrasonography of the Bovine Udder and Teat. Vet Clin Food Anim 25: 669-6685.
(2) Ollivet T. and Buczinski S. 2016. On-Farm Use of Ultrasonography for Bovine Respiratory Disease. Vet Clin Food Anim 32: 19-35.
(3) Braun, U. 2016. Ultrasonographic Examination of the Reticulum, Rumen, Omasum, Abomasum and liver in calves. Vet Clin Food Anim 32: 85-107.
(4) Condino M.P., T. Ajito, K. Sato, K. Hyakutake, K. Suzuki and K. Taguchi. 2012. Milk-flow, ultrasonographic, thelescopic and histopatological characteristics of the teat in cows with toxic mastitis. Res Vet Sci 93: 865-871.