The effect of cranial cruciate ligament insufficiency on caudal cruciate ligament morphology: An experimental study in dogs

OBJECTIVES: To investigate the effect of cranial cruciate ligament (CrCL) insufficiency on morphology of the canine caudal cruciate ligament (CdCL). STUDY DESIGN: In vivo experimental study. ANIMALS: Five adult foxhounds. METHODS: Two years after CrCL transection, the histologic appearance of CdCLs from CrCL-deficient and unoperated contralateral control (CrCL-intact) stifle joints were evaluated using light and transmission electron microscopy. RESULTS: CdCLs from CrCL-deficient joints had extracellular matrix changes, characterized by chondroid metaplasia and disruption of cell architecture. Percent of small-diameter fibrils in CdCLs from CrCL-deficient joints was significantly greater (P <.05) than that in CdCLs from CrCL-intact joints. Collagen fibril density in CdCLs from CrCL-deficient joints (41.09 +/- 5.39%) tended to be less than that in CdCLs from CrCL-intact joints (52.96 +/- 6.92%); however, this difference was not significant (P =.056). Mean eccentricity (ratio of minor to major diameters) of collagen fibrils was significantly (P <.0001) lower for CdCLs from CrCL-deficient joints (0.85 +/- 0.016) when compared with that for CdCLs from CrCL-intact joints (0.87 +/- 0.015). CONCLUSIONS: Significant alterations were found in the morphology of CdCLs from CrCL-deficient joints. These changes may be associated with repetitive microtrauma to the CdCL secondary to instability or enzymatic degradation in the hostile synovial environment of an unstable joint. CLINICAL RELEVANCE: Regardless of the cause, the switch to a predominantly small-diameter collagen fibril profile may reflect compromised material properties of the CdCL. This should be taken into account when considering surgical techniques that rely on the CdCL to stabilize CrCL-deficient stifles.     

Acute cortisol responses of calves to scoop dehorning using local anaesthesia and/or cautery of the wound

Objective To measure plasma cortisol responses in calves dehorned using a scoop after administration of local anaesthesia and/or cautery of the wounds.
Design A physiological study with controls.
Procedure There were six treatments: control handling with and without local anaesthesia, dehorning, dehorning after local anaesthesia, dehorning followed by wound cautery, and dehorning after local anaesthesia followed by wound cautery. Blood samples were taken before and after dehorning.
Results Dehorning caused an increase in plasma cortisol concentrations, which decreased a little to plateau values and then declined to pretreatment values 3 to 4 h after dehorning. The peak was smaller after local anaesthesia was administered but when its effects wore off, cortisol concentrations increased and thereafter were similar to those in the dehorned animals. The combination of local anaesthesia and cautery resulted in a plasma cortisol response similar to those in control calves with or without local anaesthesia.
Conclusions If plasma cortisol concentrations reflect the distress being experienced by the calves, then local anaesthesia reduces the acute distress for about 3 h after dehorning but not during the subsequent 3 to 4 h. Combining local anaesthetic and cautery prevented the significant increase in plasma cortisol following dehorning and may eliminate the acute distress caused by scoop dehorning.     

Management of inappetant sheep during export by sea

In the first of 2 experiments, a simulated voyage was conducted to examine the effects of various treatments on bodyweight change and feeding frequency of inappetant sheep at the end of lot-feeding (non-feeders). The treatments, applied during simulated shipping, were: normal quantities of feed and length of troughs; extra trough length; extra feed. Adult Merino wethers (n = 108) were used in each treatment. A voyage to the Middle East was then conducted to establish whether shipboard mortality could be reduced by separating non-feeders (n = 305) from feeders (n = 5,620) late in the feedlot hase and housing the groups separately aboard ship. A control group of non-feeders (n = 215) mixed with feeders (n = 5,732) was used for comparison. Bars (marker bars), containing a coloured dye, were attached to feed troughs to mark sheep that fed. Most non-feeders (82%) began eating when placed in shipping pens in both studies. However, there was no significant difference in percentage of sheep that fed between non-feeders given extra trough length or extra feed compared with non-feeders given standard management at any stage of simulated shipping. There was no significant difference in mean bodyweights between treatment groups on days 1, 8 and 15 of simulated shipping. Differences in bodyweight on d 22 were probably associated with different levels of gut fill. Death rates were not significantly different in separated and control groups (1.1%, 0.9%, P = 0.6) in the voyage of 14 d to the Middle East.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determination of Feeder Cell‐Based Cellular Niches Supporting the Colonization and Maintenance of Spermatogonial Stem Cells from Prepubertal Domestic Cat Testes

Recently, isolation and in vitro culture of putative spermatogonial stem cells (SSCs) in the domestic cat have been conducted. However, the cellular niche conditions that facilitate the establishment and long‐term maintenance of feline SSCs (FSSCs) have not been described. Therefore, we investigated the type of feeder cells used to stimulate colony formation and growth of FSSCs among the various factors in the FSSC niche. Spermatogonial stem cells isolated from feline testes were cultured on mitotically inactivated testicular stromal cells (TSCs) derived from cats, dogs and mice, and mouse embryonic fibroblasts (MEFs). The formation and growth of colonies derived from SSCs cultured on each type of feeder cell were identified at passage 0, and the morphology, alkaline phosphatase (AP) activity and expression of SSC‐specific genes in surviving colonies were investigated at passage 4. Among these diverse feeder cells, TSCs from cat showed the greatest colony formation, growth and maintenance of FSSCs, and SSC colonies cultured by passage 4 showed a typical dome‐shaped morphology, AP activity and expression of SSC‐specific genes (NANOG, OCT4, SOX2 and CD9). Accordingly, these results demonstrate that feline TSCs could be used as feeder cells to support the establishment and maintenance of SSCs from domestic cats.     

Correlative biomechanical and histologic study of the cranial cruciate ligament in dogs

The mechanical properties of the cranial cruciate ligament were determined, using unilateral bone-ligament-bone preparations from 65 dogs of various ages and body sizes. Tensile loading of the cranial cruciate ligament from 1 of each pair of stifle joints demonstrated a decrease in material properties (modulus, maximum stress, strain energy) with aging. The decreases in maximum stress and strain energy with age were significantly less (P less than 0.05 and P less than 0.05, respectively) in the cranial cruciate ligament from dogs weighing less than 15 kg, compared with those weighing 15 kg or more. The cranial cruciate ligament and remaining femorotibial ligaments were collected from the opposite stifle joints and examined microscopically. By 5 years of age, the cranial cruciate ligaments of dogs weighing greater than 15 kg consistently had microscopic evidence of degenerative disease (loss of ligamentocytes, metaplasia of surviving ligamentocytes to chondrocytes, and failure to maintain collagen fibers and primary collagen bundles) which progressed in severity with age. The caudal cruciate ligaments were similarly affected, although the degenerative changes were rarely as severe as in the cranial cruciate ligament. The collateral ligaments underwent minimal degeneration. Sex differences had no bearing on degeneration. The cranial cruciate ligaments in dogs weighing less than 15 kg generally had less severe alterations than those in heavier dogs, and the onset of the degenerative process was delayed by several years. Cranial cruciate ligaments removed from dogs after ligament failure not only had degenerative disease, but also had undergone unsuccessful attempts at repair. In contrast, fibrous repair was rarely present in intact ligaments of asymptomatic dogs with degenerative disease of the cranial cruciate ligament.     

Cardiopulmonary effects of reverse Trendelenburg position at 5° and 10° in sevoflurane-anesthetized steers

Objective

To assess the cardiopulmonary effects caused by reverse Trendelenburg position (RTP) at 5° and 10° in sevoflurane-anesthetized yearling steers.