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Biomedical subjects

N R Perkins

Publications and source records attributed to N R Perkins.

12 recordsLinked to original sources
PubMed1997

Prevalence of fetal maldispositions in equine referral hospital dystocias.

A retrospective investigation was performed to determine the population characteristics of horses presented for dystocia at 2 equine referral hospitals and the types of fetal maldispositions among these horses. The study population consisted of a similar number of Thoroughbreds (25%), Standardbreds (24%) and draft horses (22%). Most of the current literature pertaining to equine obstetrics is based on a predominately draft horse population (63%). The latter population appeared to have more transverse presentations (P = 0.06), possibly because of the higher number of draft mares. In our study, 43% (6/14) of the transverse presentations occurred in draft breeds. Furthermore, 18% of the draft mare dystocias (6/33) were transverse presentations whereas only 8% (6/73) of the 2 major light breeds (Thoroughbred n = 3; Standardbred n = 3) had transverse presentation dystocias. Despite the significant breed differences between the 2 populations (P < 0.001), the prevalence of all other fetal maldispositions was not different from those previously reported. Severe dystocia was often multifactorial, with 86% of cases involving malposture and over half (58%) of these involving more than one extremity. Head and/or neck deviation were a major reason for referral. In 30% of cases malposition was a factor, and abnormal presentation was involved in 24% of referrals.

Age Factors↗
PubMed1995

Cesarean section.

Cesarean section has become a common surgical procedure and there is a tendency for both veterinarians and their clients to regard it as routine. It is important to remember, however, that a cesarean section entails major abdominal surgery, with inherent risks, irrespective of the prevailing conditions or personnel involved.

Anesthesia↗
PubMed1994

Reproductive emergencies in the mare.

This article briefly reviews the clinical management of emergency conditions likely to be encountered by veterinarians responsible for the reproductive health of mares. The article discusses rectal tears, breeding injuries, uterine torsion, placental hydrops, and prepubic tendon rupture. A major component discusses a recommended approach to dystocias, and the management of such complications as uterine rupture and prolapse and postpartum hemorrhage. Management of retained fetal membranes and septic metritis is addressed.

Animals↗
PubMed1994

Reproductive emergencies in the stallion.

Topics addressed in this article include complications of castration, scrotal and inguinal hernias, torsion of the spermatic cord, traumatic injuries to the external genitalia, and posthumous collection of spermatozoa. A concise overview of the clinical management of emergency cases is provided.

Animals↗
PubMed1993

Pulsatile secretion of luteinizing hormone and progesterone in mares during the estrous cycle and early pregnancy.

Existence of ultradian variation in serum progesterone concentration and the relation between progesterone and luteinizing hormone (LH) secretory patterns were investigated in nonpregnant and pregnant mares. Blood samples were taken every 15 minutes for a 24-hour period on day 8 of the estrous cycle and day 18 of pregnancy, respectively. Progesterone and LH concentrations were determined by radioimmunoassay. Progesterone was secreted in pulsatile manner in nonpregnant and pregnant mares. Luteinizing hormone also was secreted in a pulsatile manner in both groups of mares. There was little temporal relation between LH and progesterone pulses in either pregnant or nonpregnant mares.

Activity Cycles↗
PubMed1992

Uterine torsion and uterine tear in a mare.

A 15-year-old Standard-bred mare was examined because of signs of abdominal discomfort in late gestation. Palpation per rectum revealed tight broad ligaments above and below the uterus, with the right broad ligament running across the top of the uterine body down toward the left, ventral side of the abdomen. A diagnosis of counterclockwise uterine torsion was made and surgical correction was approached via a left, flank laparotomy with the horse standing. The uterus was repositioned and a uterine tear encompassing 180 degrees of the uterine surface was found in the lateral, uterine body just cranial to the cervix. A live colt was delivered vaginally after uterine repositioning and the laparotomy incision was closed. The uterine tear was then repaired via a blind, vaginal approach. The mare was discharged 10 days after surgery. Repair per vaginum of a uterine tear is presented as an alternative treatment in cases for which the tear is recent, abdominal contamination is minimal, and the tear is easily accessible from the vaginal approach.

Animals↗
PubMed1990

Pathways of lymph flow from superficial tissues in the legs of horses.

Pathways of peripheral lymph flow from the legs in horses were studied with casts, and with light and electron microscopic techniques. Although lymph nodes in horses occur in large groups, each lymph vessel draining from the periphery appeared to terminate on a single node within a group. The larger branches of each vessel divided either on the node surface or after penetrating into the node, and 25 to 60 terminal afferent vessels entered either the subcapsular, medullary or trabecular sinuses. Numerous initial efferent lymphatics arose either within the medulla, or at its surface, and they often coalesced to form an anastomosing network on the node surface. Almost all of the one to four efferent lymphatics that left the vicinity of the node terminated on other nodes, usually within more centrally placed groups. This arrangement may aid in the amplification and propagation of immune responses initiated in primary nodes.

Animals↗
PubMed1989

Pathways between lymph vessels and sinuses in lymph nodes: a study in horses.

The pathways through which lymph flows from terminal afferent lymphatics to the lymph sinuses, and from the sinuses to initial efferent lymphatics, were studied in horse lymph nodes by using Microfil casts and electron microscopy. Terminal afferent lymphatics are continuous with the subcapsular sinus through oval holes, about 3 microns wide, along their length, and through larger openings near their end. Other terminal afferents penetrate into the node within trabeculae and are supported by processes across the lumen. They connect with trabecular and medullary sinuses through oval or round holes, generally 20-30 microns across. Some of these have processes, similar to the luminal strands of the adjacent sinuses, extending across them, apparently providing reinforcement. Initial efferent lymphatics receive lymph from medullary sinuses through holes which are similar to those in afferent lymphatics, though more common, especially near the origin of the vessel. Initial efferents within the medulla appear to be supported by the luminal strands of the surrounding medullary sinuses. It seems likely that these strands, like the trabeculae which surround the penetrating afferent lymphatics, may help to keep the lymphatic vessels open as the node swells while draining an area of infection.

Animals↗
PubMed1985

Effect of development of the ovine forestomachs on the anatomy of portal vessels and on the intrahepatic distribution of portal blood.

The two main tributaries of the ovine portal vein are the splenic vein, which carries blood mainly from the spleen and forestomachs, and the cranial mesenteric vein. In newborn lambs, these veins are of similar size and they converge at an angle of about 120 degrees. Blood which is carried from the intestines in the cranial mesenteric vein is not completely mixed with that from the splenic vein and it is preferentially distributed to the right side of the liver. As the fore-stomachs develop, the splenic vein becomes relatively larger than the cranial mesenteric and its direction of flow becomes oriented more caudally. Thus in the portal vein of sheep, blood in the cranial mesenteric vein meets a larger volume of blood flowing in almost the opposite direction from the splenic vein. As a result, the extent of mixing of blood in the portal vein of adult sheep is much greater than in young lambs.

Animals↗
PubMedDate not supplied

Determinants and utility of the anion gap in predicting hyperlactatemia in cattle.

The objectives of this study were to investigate the determinants of the anion gap (AG) in cattle and to evaluate the utility of AG in detecting hyperlactatemia in sick neonatal calves and adult cattle. The AG was calculated as AG = ([Na+] + [K+])-([Cl-] + [HCO-3]), with all values in mEq/L. The AG of healthy neonatal calves (n = 16) was 29.6 +/- 6.2 mEq/L (mean +/- SD), and the blood L-lactate concentration ranged from 0.5 to 1.2 mM/L. The AG was significantly (P < .05) correlated with serum phosphate (r = .66) and creatinine (r = .51) concentrations. The AG of neonatal calves with experimentally induced diarrhea (n = 16) was 28.6 +/- 5.6 mEq/L, and the blood L-lactate concentration ranged from 1.1 to 2.9 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .67), serum phosphate concentration (r = .63), creatinine concentration (r = .76), and blood pH (r = -.61). The AG of adult cattle with abomasal volvulus (n = 41) was 20.5 +/- 7.8 mEq/L, and the blood L-lactate concentration ranged from 0.6 to 15.6 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .60), serum phosphate concentration (r = .71), creatinine concentration (r = .65), albumin concentration (r = .47), total protein concentration (r = .54), blood pyruvate concentration (r = .67), and blood pH (r = -.41) but not plasma beta-OH butyrate concentration. The results indicate that the AG in cattle is only moderately correlated with blood L-lactate concentration and is similarly correlated with serum phosphate and creatinine concentrations in neonatal calves and adult cattle, as well as with serum albumin and total protein concentrations in adult cattle. Anion gap determination is of limited usefulness in predicting blood L-lactate concentration in sick cattle, whereas the correlation between AG and serum creatinine concentration in sick cattle suggests that an increased AG should alert the clinician to the potential presence of uremic anions.

Abomasum↗