FROM FERTILIZATION TO FOALING TO WEANING


ile water or saline. An ovum pick type probe or a microconvex 7.5–10-mHz ultrasound probe is disin- fected, rinsed with distilled water and 70% alcohol, and the probe is secured into a vaginal probe hous- ing. Sterile lubricant is applied to the probe, and the probe housing is lubricated with sterile lubri- cante and held guarded by the sterile, lubricated, gloved hand of the veterinarian. Mares are placed in a stocks and sedated with


20 mg acepromazine,f detomidine hydrochlorideg (0.01–0.02 mg/kg IV), and butorphanol tartrateh (0.01–0.02 mg/kg IV) and administered hyoscine bu- tylbromidei (0.1 mg/ kg, IV) to relax the rectum. The mare’s tail is wrapped, rectum emptied, and convention transrectal ultrasound examination per- formed using a linear probe to identify the ovary and area on the ovary or ovaries of interest. It is essen- tial to identify the ovary to be biopsied and the region of the ovary to be biopsied. The perineum is prepared and cleansed as if for breeding or artificial insemination. Following sedation, caution must be taken so the mare’s head does not drop onto the door of the stocks resulting in asphyxiation and collapse. The assembled covered or disinfected probe housing or unit is lubricated and inserted, using a sterile gloved hand and arm, into the vagina and positioned at the vaginal fornix lateral to the cervix, ipsilateral to the ovary to be sampled. The operator then re- moves their hand from the vagina and inserts their arm in the rectum, removes any manure, locates the ovary or ovaries to be biopsied and manipulates and positions the ovary adjacent to the ultrasound probe in the vagina. The ovary is often manipulated cra- nial into the abdomen and then flipped up over the broad ligament for this purpose. The entry point to the needle tract should be kept covered either by a sterile plastic cover, or using a sterile towel during this manipulation to prevent contamination. The ovary is carefully examined using ultrasound. The probe housing containing the ultrasound probe is manipulated along with the ovary so the region of the ovary to be biopsied is transected by an on- screen needle track. The biopsy instrument should be placed on a ster-


ile field and handled using sterile gloves from this point forward. The biopsy instrument is cocked by pulling back on the handle resulting in an audible click. The biopsy needle tip and side of the biopsy needle tip is then lightly lubricated using a sterile lubricant.e The biopsy needle is inserted carefully into the prepared needle channel of the probe hous- ing and advanced until it meets resistance in the front of the vagina. At this time the veterinarian supporting the ovary through the rectum against the vaginal wall must hold the ovary steady and firmly against the vaginal probe. A biopsy needle guide may or may not be used. The ovary must be positioned so the region to be biopsied is accessible, such as with the biopsy track bisecting the area of interest. The depth needed to reach the target area in the ovary is assessed by evaluating the centime-


ter marks on the ultrasound image. The biopsy needle is then inserted into the ovary at approxi- mately that depth using a controlled stabbing mo- tion and real time visualization of the biopsy needle movement. The biopsy needle is advanced by hold- ing the shaft of the biopsy needle near the needle port or retracted along the track into the target area of the ovary with consideration for which biopsy method will be applied. The handle of the biopsy instrument may be problematic to use for position- ing the biopsy needle, as it may be accidentally fired. The authors recommend that only the side of the needle should be used for positioning. Therefore, when placing the biopsy needle into the area of interest, the authors recommend avoid handling the end of the instrument. An unplanned firing of the needle may puncture the rectum or the veterinari- an’s hand in the rectum. The biopsy needle is guided into the target area by visualizing the bright echo produced by reflections generated from the di- amond scoring on the needle tip. The technique for ovarian biopsy must be chosen.


In what the authors call the two-step method, the veterinarian views the area of interest in the ovary and advances the biopsy needle tip under direct visualization to just behind the biopsy location. The needle tip is advanced to the first stop into the exact location to be biopsied by gentle pressure on the handle of the instrument and it is moved slightly to fill the notch on the biopsy needle. The biopsy instrument operator’s hand is removed from holding the side of the needle to the handle. The instru- ment is then fired by firmly pushing on the end of the instrument. An audible click will be heard. The firing motion advances the cutting sheath over the notch which captures the tissue in the notch. Using this two-step method, the biopsy needle tip does not advance when firing, rather the cutting sheath moves and closes over the notched portion of the needle to capture the sample. Alternatively, the other choice of technique called the one-step procedure is to advance the biopsy needle to the perimeter of the tissue of interest and fire the in- strument in one motion. With this method, the needle advances as the handle is pushed and sheath then cut. Note that the biopsy needle should not be held during firing with either method as this pre- vents the cutting sheath from advancing. The one-step technique advances the needle and


the cutting sheath at the same time, which results in a 2-cm advancement of the tip, and this must be accounted for during needle placement. This is why the needle tip is positioned behind the area to the biopsied. The sample should now be captured in the specimen notch of the needle. The biopsy instrument is then withdrawn. The biopsy instrument is moved to a sterile field


for removal of the biopsy core. The biopsy needle is recocked and an audible click should be heard. The needle tip is advanced to the first stop by gentle pressure on the end of the instrument to expose the


AAEP PROCEEDINGS  Vol. 65  2019 55


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