Proximal hindlimb flexion in the horse: Effect on movement symmetry and implications for defining soundness

Reasons for performing the study: Flexion tests are a common tool during the prepurchase and clinical lameness examination, yet studies quantifying the effect of flexion, apart from distal forelimb flexion in sound horses, are sparse. Objectives: To investigate the effect of proximal hindlimb flexion on perceivable and measurable changes in movement symmetry in horses with objective movement symmetry falling within the margins of ‘sound’. Methods: Thirteen horses, selected based on objective movement symmetry, were instrumented with inertial sensors on left and right tuber coxae and over the os sacrum. Vertical movement symmetry was quantified at trot before and after proximal hindlimb flexion, with a repeat of flexion after 5 min. Video recordings of the horses were assessed visually. Results: Proximal hindlimb flexion introduced additive changes in movement symmetry to the individual baseline movement, with a tendency towards smaller effects with increasing stride number. The main systematic effect was a decrease in upward movement of the os sacrum following mid‐stance of the flexed limb and an increase in upward movement following mid‐stance of the nonflexed limb, also manifesting in a ‘hip hike’ of the flexed limb; these findings reflected increased movement asymmetry following flexion. Depending on individual baseline asymmetry, flexion can also increase movement symmetry. Conclusions: Proximal hindlimb flexion can exacerbate subtle asymmetry when performed carefully. Variation in measured symmetry following flexion within and between horses showed that the individual response to flexion is highly variable. Potential relevance: Proximal hindlimb flexion may elevate the asymmetry of a slightly lame limb above the threshold for visibility, thus assisting in the clinical gait examination. Further work is needed to examine the causes for a positive response to flexion and possible differences between sound and lame horses as well as horses of different athletic disciplines.     

Molecular phylogenetic analysis of Onchocerca lupi and its Wolbachia endosymbiont

The morphology of Onchocerca lupi, responsible for canine ocular onchocercosis, is unique within the genus. Earlier analyses of the 5S ribosomal RNA gene spacer region sequence of the parasite and the 16S ribosomal RNA gene sequence of its Wolbachia endosymbiotic bacteria (Rickettsiales) supported the morphological and biological arguments that O. lupi is a distinct species. However, the exact phylogenetic position of O. lupi and its endosymbiont could not be unambiguously determined. Herein we report analyses based on the mitochondrial cytochrome oxidase I (COI) gene of the filarial species and the Wolbachia surface protein (wsp) and the bacterial cell-cycle ftsZ genes of their wolbachiae. Our results indicate that O. lupi separated from other Onchocerca spp. early in evolution. This is in line with the previous morphological analysis demonstrating that O. lupi is an atypical Onchocerca species showing both primitive and evolved characters. The phylogenetic trees generated for the COI sequences of filariae and the wsp and ftsZ sequences of their wolbachiae were congruent with each other, which supports the hypothesis that nematodes and their Wolbachia endobacteria share a long co-evolutionary history.     

Use of human intravenous immunoglobulin in dogs with primary immune mediated hemolytic anemia

Immune mediated hemolytic anemia (IMHA) in dogs is a severe disease with a high mortality rate. As human immunoglobulin (HIG) was reported to be beneficial for the treatment of IMHA in dogs we examined the influence of HIG on the course of the disease in our dogs with IMHA. Of 22 dogs with primary IMHA 9 dogs received in addition to routine immunosuppressive therapy HIG at a dose of 0.19 to 0.68 g/kg (median 0.35 g/kg), 13 dogs did not receive HIG (-HIG group). Both groups were similar in terms of age, weight, the presence of autoagglutination, spherocytosis, positive Coombs' test, icterus and pigmenturia. The lowest hematocrit measured during the disease was significantly lower in the +HIG group compared to the -HIG group and dogs in the +HIG group received significantly more transfusions than those of the -HIG group. This is an indication for more severe disease signs of the +HIG group dogs. Although mortality during hospitalization and the time from hospital admission to release or death was not significantly different between the two groups, we interpret this similar course of the IMHA despite more severe signs of the +HIG group dogs as a potential positive effect of the HIG therapy.     

Antigen-specific IgG(T) responses in natural and experimental cyathostominae infection in horses

Equine clinical larval cyathostominosis is caused by simultaneous mass emergence of previously inhibited larvae from the mucosa of the colon. Clinical signs include diarrhoea, colic, weight loss and malaise, and in up to 50% of cases, the disease results in death. Cyathostominae spend a large part of their life cycle as larval stages in the intestinal mucosa. Definitive diagnosis is difficult due to the lack of diagnostic methods for pre-patent infection. In the present study, the enzyme-linked immunosorbent assay (ELISA) was used to investigate isotype responses to larval cyathostominae somatic antigen. Measurement of anti-larval IgG(T) responses appeared to have the most immunodiagnostic potential. An increase in IgG(T) response was detected to crude larval antigen by 5 weeks post-infection (PI) in individual infected ponies. Subsequently, IgG(T) responses to larval and adult somatic extracts were examined by Western blotting using sera from experimentally-infected horses and helminth-naive animals (n=6). Two antigen complexes, designated A and B, in larval somatic antigen were recognised specifically by the infected animals by 7 weeks PI. Sera taken from 23 endemically-infected animals, whose cyathostominae burdens had been enumerated, were also used to identify putative diagnostic antigens. Eighteen horses had positive mucosal worm burdens (range 723-3,595,725) and all but two of these animals had serum IgG(T) antibody specific to either complex. Moreover, IgG(T) responses specific to antigen complexes A and B were absent in all five parasite negative horses that were tested. Serum IgG(T) responses to either of the two complexes were identified in five clinical cases tested. IgG(T) responses to adult antigen somatic extracts were more heterogeneous, with no clear pattern between experimentally-infected ponies and helminth-free controls. The results indicate that increases in serum IgG(T) to mucosal larvae occur in the pre-patent period and that two antigenic complexes within somatic preparations of these stages have immunodiagnostic potential.     

Effects of feeding ergovaline on lamb performance in a heat stress environment

Lambs exposed to a heat-stressed environment (33 degrees C, 50% relative humidity) were used in three experiments to determine whether ergovaline (EV) is the primary toxin involved in fescue toxicosis. The first study evaluated the effects of feeding diets containing increasing levels of endophyte-infected tall fescue seed (E+) and decreasing levels of endophyte-free tall fescue seed (E-). The second and third study evaluated the response to a diet that contained synthetic EV added to an E- diet and the response to a diet containing endophyte-infected ryegrass seed (R+) with an elevated concentration of EV. In Exp. 1, lambs were fed diets of: 1) 10% E- and 0% E+, 2) 5% E- and 5% E+, or 3) 0% E- and 10% E+. Increasing the percentage of E+ in the diet resulted in a linear decrease (P < 0.01) in feed intake (as-fed basis), skin temperature, thermocirculation index (TCI), and serum prolactin. Body weight gain also decreased (P < 0.06). Respiratory rate and core body temperature were not affected by the 5 or 10% E+ diets. In Exp. 2, lambs were fed diets that contained: 1) 10% E-, 2) 10% E- with synthetic EV added at a level equivalent to the 10% E+ diet, or 3) 10% E+. Feed intake (as-fed basis), body weight gain, and skin temperature did not differ for lambs fed the E- and EV diets. The EV diet elicited a decrease (P < 0.05) in TCI and prolactin compared with the E- diet. The TCI for lambs fed EV did not differ (P > 0.10) from the E+ lambs; however, serum prolactin was lower (P < 0.05) for lambs on the E+ diet than for those fed EV. Core body temperature was not affected (P > 0.10) by feeding EV or E+ fescue seed in Exp. 2. In Exp. 3, lambs were fed diets that contained: 1) 10% E-, 2) 3.24% R+ and 6.76% E-, which added an equivalent amount of EV to E+ diets but reduced concentrations of other ergot alkaloids, or 3) 10% E+. Lambs fed the E+ diet and maintained at 33 degrees C had lowered feed intake (as-fed basis), skin temperature, and TCI compared with lambs fed the E- or R+ diets (P < 0.05). Lambs fed the E+ diet had increased rectal temperatures and lowered serum prolactin compared with lambs on the R+ diet (P < 0.05). Lambs on the R+ diet had a greater rectal temperature and lower serum prolactin than lambs on the E- diet (P < 0.05). These results suggest that EV is a fescue toxin; however, other alkaloids might work synergistically with EV, causing the full expression of fescue toxicosis.     

Recurrent fever as the only or predominant clinical sign in four dogs and one cat with congenital portosystemic vascular anomalies

Fever is not considered a typical clinical sign in animals with portosystemic vascular anomalies (PSVA). In a time period of 8 years, PSVA was diagnosed in 23 cases (20 dogs, 3 cats) at the Animal Hospital of the University of Zurich. Of these, recurrent fever was the only, the predominant or an early sign in 5 animals. Fever and associated unspecific clinical signs like lethargy, inappetence, and reluctance to move were present for weeks to months before the final diagnosis of PSVA was made. It was the lack of typical and well-known signs of PSVA that obscured and delayed the diagnosis. Therefore, PSVA should be included in the differential diagnosis of animals with fever of unknown origin (FUO).     

Congenital cardiac diseases in dogs: a retrospective analysis

In a time period of 6 years, 158 congenital cardiac defects were diagnosed in 146 dogs at the Clinic for Small Animal Medicine University of Zurich. In respect to all dogs with cardiac disease, these were 23.5% of the cases. Most common defects were subaortic stenosis (SAS, 31.5%), pulmonic stenosis (PS, 23.3%), ventricular septal defect (VSD, 14.4%), patent ductus arteriosus (PDA, 13.7%) and tricuspid dysplasia (TD, 7.5%). Complex defects were found in 8.2% of the dogs. Although single dogs per breed were affected by various defects, some breed-related tendencies could be observed. We found PS more numerously in boxers and Jack Russell Terriers whereas SAS, VSD and TD were also found in breeds reported to be predisposed. Congenital cardiac defects are an important clinical entity, and knowledge of prevalence is helpful when considering the differential diagnosis and for making a tentative diagnosis in an individual case.     

Chemoattraction and chemorepulsion of Strongyloides stercoralis infective larvae on a sodium chloride gradient is mediated by amphidial neuron pairs ASE and ASH, respectively

Depending on its concentration, sodium chloride acts as either an attractant or a repellant to the infective larvae (L3i) of Strongyloides stercoralis. On a concentration gradient, L3i are attracted to 0.05 M NaCl, but repelled by 2.8M. To test the hypothesis that amphidial neurons ASE and ASH might mediate attraction and repulsion, respectively, these neurons, and control neurons as well, were ablated in hatchling larvae with a laser microbeam. After the larvae attained infectivity (L3i), they were tested on a NaCl gradient. When placed at low salinity, 73.5% of normal controls migrated "up" the gradient, while 26.4% crawled randomly. In contrast, only 20.6% of ASE-ablated L3i migrated "up" the gradient, while 79.4% migrated randomly. Ablation-control ASK-ablated L3i (58.8%) migrated "up" the gradient while 41.1% crawled randomly. When placed at a region of high salinity, 100% of normal control L3i migrated "down" the gradient, whereas 62.5% of ASH-ablated L3i migrated randomly, the remaining 37.5% migrating "down" the gradient. In sharp contrast with ASH-ablated L3i, 94.1% of ablation-control larvae, i.e. ASK-ablated L3i, migrated "down" the gradient. Migration behavior of ASE- and ASH-ablated L3i was significantly different (P < 0.001) from that of ASK-ablated L3i and normal controls. It is noteworthy that 87.5% of ASE-ablated L3i that failed to exhibit chemoattractive behavior were actively chemorepelled from high salinity. Also, 70.0% of ASH-ablated L3i that failed to be chemorepelled from high salinity were capable of chemoattractive behavior, indicating that the worms had retained their behavioral responses except for those associated with the targeted neurons.     

Analysis of differential protein expression in Actinobacillus pleuropneumoniae by Surface Enhanced Laser Desorption Ionisation--ProteinChip (SELDI) technology

Actinobacillus pleuropneumoniae (APP) is the aetiological agent of porcine pleuropneumonia. An increased understanding of its molecular basis of pathogenicity and vaccine development will be facilitated by the availability of sequence data from a complete genome which, by analogy to other bacteria, is predicted to encode many proteins in the molecular mass range 3-20kDa. However, conventional techniques to study bacterial protein expression, such as SDS-PAGE and 2-dimensional electrophoresis, typically focus on the 15-200kDa range. In this study we have evaluated Surface Enhanced Laser Desorption Ionisation-ProteinChip (SELDI) technology for the analysis of protein expression, in particular those of <20kDa, of APP grown under different environmental conditions. Cytoplasmic/periplasmic and outer membrane protein fractions were obtained from the APP wildtype serotype 1 strain 4074 grown in Brain Heart Infusion (BHI) broth (+different concentrations of NAD), BHI containing pig serum or defined medium. Optimum conditions for SELDI profiles included a sample size of 1 microg and the use of sinapinic acid as the energy absorbing matrix. In the <20kDa range, the SELDI profiles obtained from wild-type bacteria grown in rich medium plus 33-66% pig serum were most similar to those grown in defined medium. The SELDI profiles of extracts of the wild-type and of an rpoE mutant were similar although there were clear differences. The results suggest that SELDI is a useful complementary approach to conventional proteomic analytical methods with APP, and presumably other bacterial pathogens, being particularly suited for analysis of proteins in the <20kDa mass range.