Formaldehyde Vapor Levels in a Gross Anatomy Laboratory During Dissection of the Dog

Breathing zone formaldehyde vapor levels were measured in a veterinary gross anatomy laboratory during dissection of greyhound dogs. Measurements were conducted throughout the academic quarter during which dissection took place. Measurement was accomplished using 3 M Company formaldehyde monitors (# 3720). The overall mean time weighed average was 0.197ppm to which students and faculty were exposed a total of 72 hours.     

Interday variation in vertical ground reaction force in clinically normal Greyhounds at the trot.

OBJECTIVE: To determine the effect of interday variation on vertical ground reaction force variables in dogs. ANIMALS: 52 clinically normal Greyhounds of either sex weighing between 22 and 35 kg. PROCEDURE: Dogs were led at a trot across a floor-mounted force platform to determine vertical ground reaction force variables (peak [PFz] and impulse [IFz]) from hind limbs. Data were collected from each dog on 3 consecutive days. Variance components were estimated, using maximal likelihood to evaluate contributions of interday variation within dogs and variation attributable to dogs and repetitions. An ANOVA was used to test significance of interday variation within dogs and day within dog interactions. RESULTS: PFz, IFz, or both differed significantly from day to day for 29 of 52 dogs. Only PFz differed significantly among days for 16 dogs, and only IFz differed among days for 5 dogs. The PFz and IFz differed significantly from day to day in 8 dogs. Using ANOVA, the difference for PFz and IFz among days within dogs was significant. CONCLUSIONS: Effect of day within dog variation (interaction) should be considered as a component in statistical models in which data from 1 day are evaluated against data from the same subject on another day. We propose a statistical model that incorporates an accommodation for interday variation. Investigators should determine the factors that affect their studies, including the extent of interday variation, and compensate for the variation attributable to each factor in the statistical models used to analyze their data.     

A Paternal Fish Oil Diet Preconception Modulates the Gut Microbiome and Attenuates Necrotizing Enterocolitis in Neonatal Mice

Epidemiology and animal studies suggest that a paternal history of toxicant exposure contributes to the developmental origins of health and disease. Using a mouse model, our laboratory previously reported that a paternal history of in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increased his offspring’s risk of developing necrotizing enterocolitis (NEC). Additionally, our group and others have found that formula supplementation also increases the risk of NEC in both humans and mice. Our murine studies revealed that intervening with a paternal fish oil diet preconception eliminated the TCDD-associated outcomes that are risk factors for NEC (e.g., intrauterine growth restriction, delayed postnatal growth, and preterm birth). However, the efficacy of a paternal fish oil diet in eliminating the risk of disease development in his offspring was not investigated. Herein, reproductive-age male mice exposed to TCDD in utero were weaned to a standard or fish oil diet for one full cycle of spermatogenesis, then mated to age-matched unexposed females. Their offspring were randomized to a strict maternal milk diet or a supplemental formula diet from postnatal days 7–10. Offspring colon contents and intestines were collected to determine the onset of gut dysbiosis and NEC. We found that a paternal fish oil diet preconception reduced his offspring’s risk of toxicant-driven NEC, which was associated with a decrease in the relative abundance of the Firmicutes phylum, but an increase in the relative abundance of the Negativicutes class.     

The Apical Ligaments of the Penis of the Goat and Sheep

The penile apical ligaments of 13 goats and 8 sheep were dissected and described. Unlike the single apical ligament of the bull penis, both goats and sheep had one ligament on each side of the apex of the penis with no apparent connection over the dorsal surface. These lateral apical ligaments consisted of substantial connective tissue fibers that arose from the outer layers of the tunica albuginea and varied from 6.0 to 10.0 cm in length. The left apical ligament was longer and thicker than the right. The left apical ligament of the sheep penis was divided into a dorsal and a ventral branch. Both the goat and sheep possessed flattened perivenous ligaments that originated from the apical fascia and extended caudally along each side of the dorsal vein of the penis.     

A comparison of the efficiency of water and ethanol at removing formaldehyde from immersion fixed muscle tissues

The efficiency of water, ethanol solutions, isopropanol and ethylene glycol for extracting formaldehyde from fixed muscle tissue were compared. Similar samples of formalin preserved muscle were immersed in the test extraction fluids. After various storage periods the fluids were analyzed for formaldehyde content by sodium sulfite wet chemistry titration. The resulting data were compared by analysis of variance. Ethanol, isopropanol, ethylene glycol and water were found to be effective in extracting formaldehyde from formalin fixed tissue. The concentration of formaldehyde extraction by increasing concentrations of ethanol (20–40%) was linear. While 25 to 40% solutions of ethanol, 20% isopropanol and 25% ethylene glycol were significantly better at extracting formaldehyde, the actual percent formalin difference between water and the best extraction fluid (40% ethanol) was only 0.2% (2.43 versus 2.63%). This slight difference would hardly justify the added expense of using alcoholic or glycolic solutions solely for their extraction qualities. The problem of formaldehyde vapirs arising from embalmed tissue is associated with unbound and loosely bound formaldehyde. which can be removed by washing with various solutions. Precise methods for washing gross anatomical specimens are not discussed.     

LOW-FIELD MAGNETIC RESONANCE IMAGING OF THE CANINE STIFLE JOINT: NORMAL ANATOMY

Low-field magnetic resonance imaging (MRI) was performed on the stifle joints of four normal adult mongrel dogs using a 0.064 Tesla scanner. Markers were placed on each stifle joint to serve as reference points for comparing gross sections with the images. A T1-weighted sequence was used to image one stifle joint on each dog in the sagittal plane and the other stifle joint in the dorsal plane. The dogs were euthanized immediately following MRI and the stifle joints frozen intact. Each stifle joint was then embedded in paraffin, again frozen, and sectioned using the markers as reference points. On T1-weighted images, synovial fluid had low signal intensity (dark) compared to the infrapatellar fat pad which had a high signal intensity (bright). Articular cartilage was visualized as an intermediate bright signal and was separated from trabecular bone by a dark line representing subchondral bone. Menisci, fibrous joint capsule, and ligamentous structures appeared dark. In the true sagittal plane, the entire caudal cruciate ligament was often seen within one image slice. The patella was visualized as an intermediate bright signal (trabecular bone) surrounded by a low intensity signal (cortical bone). The trochlea and the intercondylar notch were difficult areas to analyze due to signal volume averaging of the curved surface of these areas and the presence of several types of tissues.     

Effects of bandage configuration on paw pad pressure in dogs: a preliminary study

Seven bandage configurations were placed on the right forepaw of six English pointer dogs to evaluate the effects that configurations have on reducing pad pressure. The "clam shell" configuration resulted in less pressure being applied to all palmar pad surfaces. For the major weight-bearing pad, a basic paw bandage with an intermediate compressible foam sponge that had a hole under the major weight-bearing pad, combined with a metal splint paw cup under the sponge, resulted in a significantly lower pressure recording than for other bandage configurations. Digital pads 3 and 5 had the greatest pressure in a basic bandage configuration. Based on pressures on these pads, a basic paw bandage with an intermediate compressible foam sponge under the major weight-bearing pad, with or without a metal splint paw cup under the sponge, helped elevate the digits to relieve pressure on them. Placing a foam sponge pad, with or without a splint paw cup under the palmar paw surface, also provided less pressure on these pads.     

Efficiency of phenoxyethanol at removing formaldehyde from immersion fixed muscle tissue

The propensities of several fluids for extracting formaldehyde from fixed muscle tissue were compared. Following formalin fixation, similar samples of muscle tissue were immersed in solutions of 0.5%, 1%, 2%, 4% phenoxyethanol, 40% ethanol, 25% ethylene glycol or water. Following storage periods of 4, 25, 50 or 100 days, the formaldehyde content of the fluids was determined by sodium sulfite titration. The solution containing 40% ethanol was clearly superior to the others. Solutions containing 2% or 4% phenoxyethanol were least effective and there was a significant inverse linear relationship between the concentration of phenoxyethanol and amount of formaldehyde extracted. This suggests that phenoxyethanol decreases the ability of water to extract formaldehyde from fixed tissues.     

Morphology of the Musculus articularis Genus in Dog with Description of Ectopic Muscle Spindles

The gross morphology of the musculus articularis genus and the location of muscle spindles at its point of insertion were studied in 18 adult dogs. The m. articularis genus was usually small and bipartite. From its originate on the cranial surface of the distal femur, it passed distally to terminate at the femoropatellar-joint capsule surface and extend into the synovial membrane. Although the m. articularis genus was usually composed of two parts, only a medial part was present in some dogs and was entirely absent in one specimen. Innervation to the m. articularis genus was provided by a branch of the femoral nerve. Muscle spindles were abundant in the termination of the muscle. Frequently, the spindles were not in contact with muscle fibres (dissociated). Muscle spindles were located in close proximity to the surface of the synovial membrane. Morphological adaptations of the m. articularis genus support its potential function as a monitor of joint movement rather than an extensor of the stifle joint.