then opened and pushed into the organ. Once in position, the jaw of the biopsy forceps is closed firmly to collect a small sample (1–2 cm) of tissue (Figures 24.2 and 24.3).Figure 24.2 Collection of an ovarian biopsy.
Bleeding can be controlled with an electrosurgical forceps. The ovary and/or uterus should be observed for at least 3–4 minutes to ensure that all bleeding has stopped prior to removing the instruments from the abdomen. Another option is to use a hernia stapling device to staple the capsule of the ovary back together.
The biopsy sample is then placed into fixative solution (i.e., 10% formalin). The container should be labeled with the name of the mare, collection date, and other pertinent information.Figure 24.3 Removal of an ovarian biopsy sample.
The fixed biopsy specimen can then be submitted to a pathology laboratory.
The instruments are withdrawn and the skin incision site is sutured closed.
Postoperative care may include administration of a non‐steroidal anti‐inflammatory drug, such as flunixin meglumine (1.0 mg/kg IV), and, as needed based on the individual clinical case, administration of antimicrobial agents. The horse should be examined periodically after the conclusion of the procedure to monitor comfort level as well as localized swelling, pain, heat, or discharge at the incision sites.
Further Reading
1 Caron JP. 2009. Equine laparoscopic surgery: here to stay? Eq Vet Educ 21(6): 301–2.
2 Caron JP. 2012. Equine laparoscopy: equipment and basic principles. Compend Contin Educ Vet 34(3): E1–E7.
3 Fisher AT, Jr. 2001. Equine Diagnostic and Surgical Laparoscopy. Philadelphia: WB Saunders.
4 Hendrickson DA. 2012a. A review of equine laparoscopy. ISRN Vet Sci 2012: article ID 492650.
5 Hendrickson DA. 2012b. Diagnostic techniques. In: Ragle CA (ed.). Advances in Equine Laparoscopy. Ames, IA: Wiley Blackwell, pp. 83–91.
25 Evaluation of the Mammary Gland
Patrick M. McCue
Equine Reproduction Laboratory, Colorado State University, USA
Introduction
The mammary gland plays a key role in allowing the fetus to survive outside the uterus. It is responsible for providing the neonate with colostral antibodies critical to survival and supplies nutrition to the foal during the first few months of life. The equine mammary gland is located high in the inguinal region of the mare. The equine mammary gland is divided into left and right halves by a connective tissue septum, each with a glandular body and teat. The glandular portion of each half is further divided by fibroelastic capsules into cranial and caudal lobes. Each of the two teats serves a cranial and caudal lobe of mammary tissue and has two teat orifices (Figure 25.1).
Abnormalities of the equine mammary gland include agalactia, premature lactation, inappropriate lactation, and mastitis. Less common issues include abscessation, neoplasia, and trauma.
Figure 25.1 Mammary gland of a mare. Note the two teat orifices visible on the end of the right teat.
Equipment and Supplies
Exam glove, alcohol swabs, sterile container (red top tube, urine cup, etc.), culture transport system, glass microscope slides, cytology stain, microscope, ultrasound.
Techinque
A visual assessment of the mammary gland should be performed initially. Udder size, shape, and symmetry should be assessed and related to the reproductive status of the mare (non‐pregnant, late‐term pregnant, postpartum, post‐weaning, etc.).
The pregnant mare’s udder will increase in size over the last 4–6 weeks of gestation. Nulliparous mares may not have much udder development until 1–2 weeks prior to parturition or even not until parturition. Fescue toxicosis should be ruled out in cases of poor udder development.
Foals born to mares with abnormally large teats may have difficulty nursing due to an inability to form a proper suction. These foals should be watched closely for adequate ingestion of milk and weighed daily to ensure intake.
A manual examination of the udder should be performed next. A hot, swollen, painful quarter is consistent with acute mastitis (Figure 25.2). In addition, edema may be present cranial to the udder in affected mares (Figure 25.3). Edema may also be present in normal mares near foaling as the blood vessels to the udder develop, due to the position of the in utero foal decreasing venous return and due to mare inactivity in late pregnancy.
Mares with inappropriate lactation or galactorrhea, such as may occur secondary to pituitary pars intermedia dysfunction, often have a small to moderate amount of mammary secretion produced in all four quarters and the overall gland is not hot or painful (Figure 25.4). Sometimes, normal, older multiparous mares may have large teat or gland cisterns that fill with secretions without active lactation or pregnancy.Figure 25.2 Enlargement of the right rear quarter of a mare secondary to mastitis.Figure 25.3 Edema cranial to the udder in a mare with mastitis.Figure 25.4 Enlargement of the entire udder in a mare with galactorrhea secondary to pituitary pars intermedia dysfunction.
Mammary fluid should be expressed and the character of the fluid assessed. Mastitic fluid is typically thick, white to slightly yellow in color (Figure 25.5), and may be blood tinged.
A cytologic evaluation of the mammary fluid may be indicated if mastitis or neoplasia is suspected. Mare milk produced during normal lactation and mammary secretion from a non‐pregnant, non‐foaling mare with inappropriate lactation should not have a large number of white blood cells on cytology. In contrast, white blood cells are abundant in mares with mastitis (Figure 25.6).
The teat should be cleaned of dirt/debris and the end disinfected with an alcohol swab prior to expression of milk for bacteriological culture (see Chapter 106).
