Effect of Four Antimicrobial Lavage Solutions on the Tarsocrural Joint of Horses

Three concentrations of povidone-iodine (0.1% w/v, 0.2% w/v, 0.5% w/v) and one concentration of chlorhexidine (0.5% w/v) were selected as antimicrobial joint lavage solutions. Through-and-through joint lavage was performed with one of these antimicrobial solutions on a tarsocrural joint of 12 horses. The contralateral tarsocrural joints (control limbs) were lavaged with a balanced electrolyte solution (BES). The effect of the lavage solution on the joints was evaluated with respect to lameness, foot flight pattern, soreness to joint palpation, articular and periarticular enlargement, and synovial fluid composition on Day 1,4, and 8 postlavage. On Day 8 postlavage, all horses were euthanized and the tarsocrural joints were examined.
All solutions induced a synovitis. Based on clinical assessment, synovial fluid protein levels, color, clarity, mucin clot forming ability, gross appearance of the joint at necropsy, and synovial membrane histologic evaluation, a similar, mild, transient, synovitis was induced by the BES and 0.1% povidone-iodine (PI) solution. The 0.2% PI solution induced a more prolonged neutrophilic response and poorer mucin clot forming ability in the synovial fluid as compared to the BES.
The 0.5% PI and 0.5% chlorhexidine solutions produced severe lameness, soreness to joint palpation, and limb enlargement. The elevated synovial fluid total protein content persisted significantly longer (p < 0.05) than the corresponding control (BES) solution. Histologic evaluation of the synovial membrane confirmed the presence of a moderate to severe neutrophilic synovitis in these treatment groups.     

Effects of Four Preparations of 0.05% Chlorhexidine Diacetate on Wound Healing in Dogs

Four chlorhexidine diacetate (CHD) antiseptic wound lavage preparations were evaluated in vivo to determine their effects on second intention wound healing in the dog in vitro to determine their relative antibacterial activity against Staphylococcus intermedius. Chlorhexidine was diluted to 0.05% in sterile water, 0.9% sodium chloride, lactated Ringers solution (LRS), and LRS that was allowed to form a precipitate with CHD. Control solutions included sterile water and LRS. There were no significant differences in wound contraction or epithelialization. All 0.05% CHD preparations provided 100% bacterial kill.     

Arthroscopic Examination of the Femorotibial Joints of Horses

A technique for satisfactory arthroscopic examination of the lateral and medial femorotibial joints of the horse is described. The entry portal is made between the middle and medial patellar ligaments with the horse on its back and the stifle flexed. This position allows easy access to view the intercondylar eminence of the tibia. From this reference point, examination of all but the most caudal and medial structures of the joints are possible by manipulating the sleeve and telescope and maintaining joint distention. In a series of 20 examinations, iatrogenic trauma was recognized only once.     

In Vitro and In Vivo Evaluation of Ferric-Hyaluronate Implants for Delivery of Amikacin Sulfate to the Tarsocrural Joint of Horses

Objective— To assess the antimicrobial elution characteristics, toxicity, and antimicrobial activity of amikacin‐impregnated ferric‐hyaluronate implants (AI‐FeHAI) for amikacin delivery to the tarsocrural joint of horses. Study Design— Experimental study. Sample Population— AI‐FeHAI implants, equine cartilage, and synovium, and horses (n=6). Methods— In vitro study: Five AI‐FeHAI were placed in saline solution with daily replacement until implant degradation. Eluent was tested for amikacin concentration and bioactivity. Synovial and cartilage explants were incubated in the presence or absence of AI‐FeHAI for 72 hours and subsequently assessed for morphology, viability, and composition. Synovial explants were incubated with Staphylococcus aureus in the presence or absence of AI‐FeHAI. Spent medium was cultured daily and explants were assessed for morphology and viability after 96 hours. In vivo study: AI‐FeHAI were placed in 6 tarsocrural joints. Standard cytologic analysis and amikacin concentration (SFAC) were determined in synovia obtained regularly for 28 days thereafter. Similar analyses were conducted after a single intra‐articular injection of amikacin 6 months later. Results— In vitro study: Amikacin concentrations exceeded 16 μg/mL and inhibited S. aureus growth for 8 days. AI‐FeHAI had no effect on cartilage explants. AI‐FeHAI eliminated bacteria from synovial explants. In vitro study: After AI‐FeHAI placement, SFAC was highest (140.78+63.81 μg/mL) at first sampling time. By 24 hours SFAC was <16 μg/mL. After intra‐articular injection, SFAC was the highest (377.91 ± 40.15 μg/mL) at first sampling time. By 48 hours SFAC was <16 μg/mL. Conclusions— A single intra‐articular amikacin injection demonstrated superior pharmacokinetics than AI‐FeHAI prepared as described. Clinical Relevance— AI‐FeHAI cannot be recommended for clinical use.     

Age Effects on Blood Gas,Spirometry, Airway Reactivity,and Bronchoalveolar Lavage Fluid Cytology in Clinically Healthy Horses

Background

Despite the increasing number of geriatric horses attended by veterinarians, there is a lack of understanding of aging‐related changes on the respiratory system of horses.

Objective

To identify aging‐related changes on the respiratory function and bronchoalveolar lavage fluid (BALF) cytology of horses.

Animals

Fifteen healthy young adult (2–11 years) and 16 healthy aged (≥20 years) horses.

Methods

The respiratory system was examined by measurement of arterial blood gases (ABG), use of respiratory inductive plethysmography (RIP) for assessment of breathing pattern and ventilatory parameters, histamine bronchoprovocation, and BALF cytology.

Results

No significant differences were detected with regard to values obtained by ABG or bronchoprovocation of young adult and aged healthy horses. In aged horses, there were significant differences in mean ± SD of the following parameters when compared to young horses: prolonged expiratory time (Te) measured by RIP (3.9 ± 1.5 s versus 3.0 ± 0.6 s), decreased percentage of alveolar macrophages (40.6 ± 11.3% versus 53.5 ± 9.6%), and increased percentage of lymphocytes (53.4 ± 9.5% versus 43.9 ± 11.0%). No correlations between airway reactivity and ventilatory parameters, ABG, or BALF cytology were found in this asymptomatic population.

Conclusions

These results suggest that aging does not cause changes in the results obtained by ABG, most RIP‐derived variables, and bronchoprovocation in the horse. A decreased percentage of macrophage and an increased percentage of lymphocytes in the BALF cytology may be expected in the asymptomatic geriatric horse and may be a result of aging.     

Morphometrical Study of Bony Elements of the Forelimb Fetlock Joints in Horses

There are many reports describing fractures in the bony elements of the equine fetlock joint and a few of these discuss possible relationships of these fractures to the mechanical loading of these bones. The likelihood of fracture must be related to the size and shape of bones involved, but information concerning the normal range in size and shape of these bones in horses is lacking. This study aimed to identify morphometrical variations of these bones within different groups of horses. Right and left metacarpal, proximal phalangeal and proximal sesamoid bones were collected from 10 Thoroughbreds (TB), five Standardbreds (SB) and eight Ponies (P) euthanized for non‐orthopaedic reasons. All bones were boiled, cleaned and dried. Dimensional parameters were measured using a custom‐built apparatus, calliper and plastic tape. The width and depth of the medial condyles of Mc3 were greater than the lateral condyles in all groups. The length to the lateral condyle was greater than the length to the medial condyle of Mc3, and the lengths of the lateral sides of the Mc3 and P1 bones were greater than the lengths of the medial sides in both forelimbs of all groups. The lateral sesamoids were similar to, or larger than, the medial sesamoids in all dimensions. There were some morphometrical variations in the bony elements of the equine fetlock joints in all groups.     

Secretoglobin and Transferrin Expression in Bronchoalveolar Lavage Fluid of Horses with Chronic Respiratory Disease

Background

Lower expression of secretoglobin and transferrin has been found in the bronchoalveolar lavage fluid (BALF) of a small number of horses with experimentally induced signs of recurrent airway obstruction (RAO) compared to healthy controls.

Hypothesis/Objectives

Secretoglobin and transferrin BALF expression will be similarly decreased in horses with naturally occurring clinical signs of RAO and in horses with experimentally induced clinical signs of RAO as compared to healthy controls and intermediate in horses with inflammatory airway disease (IAD).

Animals

Recurrent airway obstruction‐affected and control horses were subjected to an experimental hay exposure trial to induce signs of RAO. Client‐owned horses with a presumptive diagnosis of RAO and controls from the same stable environments were recruited.

Methods

Pulmonary function and BALF were evaluated from control and RAO‐affected research horses during an experimental hay exposure trial (n = 5 in each group) and from client‐owned horses (RAO‐affected horses, n = 17; IAD‐affected horses, n = 19; healthy controls, n = 5). The concentrations of secretoglobin and transferrin in BALF were assessed using Western blots.

Results

Naturally occurring and experimentally induced RAO horses had similar decreases in BALF transferrin expression, but secretoglobin expression was most decreased in naturally occurring RAO. Secretoglobin and transferrin expression were both lower in BALF of RAO‐affected horses than in IAD‐affected and control horses.

Conclusions and Clinical Importance

Secretoglobin and transferrin expression is decreased in BALF of RAO‐affected horses after both experimental and natural exposure. Secretoglobin and transferrin likely play clinically relevant roles in the pathophysiology of RAO, and may thus be used as biomarkers of the disease.     

Evaluation of Postoperative Peritoneal Lavage in Standing Horses for Prevention of Experimentally Induced Abdominal Adhesions

Objective —To evaluate the postoperative use of peritoneal lavage for prevention of experimentally induced intraabdominal adhesions in horses.
Study Design —Areas of serosal abrasion were created on the jejunum of 12 horses. Postoperatively, six horses had peritoneal lavage, and six horses did not (controls). The number of adhesions was determined at necropsy 2 weeks after surgery.
Animals or Sample Population—12 horses.
Methods —Five sites of jejunal serosal abrasion were created in each horse. A 32 French thoracic catheter was placed into the right ventral aspect of the abdomen before closure of the abdominal incision. Treated horses had abdominal lavage with 10 L of lactated Ringer's solution on four occasions, then catheters were removed from all horses 34 hours after celiotomy. Horses were necropsied at 2 weeks to quantify the number of intraabdominal adhesions.
Results —All control horses and one treated horse developed intraabdominal adhesions. The number of adhesions was significantly less ( P <.0293) in treated horses. No adverse inflammatory reactions appeared to be associated with repeated peritoneal lavage using lactated Ringer's solution or use of an abdominal drain.
Conclusions —Peritoneal lavage reduced the frequency of intraabdominal adhesions.
Clinical Relevance —When postoperative adhesions are likely to develop, postoperative peritoneal lavage may decrease the frequency of adhesion formation.     

Evaluation of 25%, 50%, and 67% Nitrous Oxide with Halothane-Oxygen for General Anesthesia in Horses

Twenty-five percent, 50%, and 67% nitrous oxide was administered to 12 horses anesthetized with halothane and oxygen. Compared to halothane-oxygen alone, there was no significant difference in heart rate, systolic, diastolic, or mean blood pressure values, arterial pH, PaCO2, or plasma bicarbonate values when nitrous oxide was included. A significant linear reduction in PaO2 values could be correlated with N2O:O2 concentrations. The halothane level required to maintain surgical anesthesia was reduced when nitrous oxide was administered, but it was not affected by changing the nitrous oxide concentrations. Nitrous oxide concentrations greater than 25% provide no additional reduction in halothane requirement and may be accompanied by PaO2 values that pose risk to the horse.     

Collateral Ligaments of the Tarsocrural Joint An Anatomic and Functional Study

Forty canine hock joints were used to study the anatomy and function of the medial and lateral tarsocrural collateral ligament complexes. Dissection of the ligaments was used to describe the anatomic arrangement, and location and tenseness in various positions. The component parts of the ligament complexes were evaluated for their contribution to stability of the tarsocrural joint. The medial and lateral tarsocrural collateral ligament complexes were composed of several components. The medial tibiotalar and lateral calcaneofibular short component parts were important static joint stabilizers in both flexion and extension. The long medial and lateral ligaments and the medial tibiocentral short component were less important in maintaining joint stability in flexion but were important in extension. The stability of the joint as a whole did not depend on any individual ligament component, but rather all components of the ligament complex, including the joint capsule and malleoli, acted together to stabilize the joint.     

Effects of Chlorhexidine Diacetate and Povidone-lodine on Wound Healing in Dogs

To correlate the results of an in vitro study with clinical response, the effects of 0.005 and 0.05% chlorhexidine diacetate and 0.1 and 1.0% povidone-iodine concentrations on wound healing were evaluated in five beagle dogs. Full-thickness skin wounds (2 X 2 cm) were irrigated once daily for 14 days with the antiseptic solutions or physiologic-buffered saline. Chlorhexidine diacetate 0.05% had significantly more bactericidal activity than povidone-iodine and saline, and both chlorhexidine diacetate concentrations had residual effects 6 hours after irrigation. Neither povidone-iodine nor saline had significant bactericidal activity. The percentages of unhealed wound area and wound contraction were calculated 7, 14, and 21 days after wounding. Healed wound area and contraction were similar in wounds treated with chlorhexidine diacetate and povidone-iodine. However, wounds treated with chlorhexidine diacetate had more healed wound area on days 7 and 14 and more contraction on days 7, 14, and 21 than saline-treated wounds. At the concentrations tested, chlorhexidine diacetate irrigations provided bactericidal activity and were more beneficial to wound healing than irrigations with saline alone. These results suggest that concentrations of chlorhexidine diacetate which are cytotoxic to tissue culture fibroblasts in vitro do not interfere with wound healing in vivo.     

In Vivo Investigation of Communication Between the Distal Intertarsal and Tarsometatarsal Joints in Horses and Ponies

The frequency of communication between the tarsometatarsal and distal intertarsal joints was investigated in 27 horses and 12 ponies. After the injection of diluted latex into the tarsometatarsal joints using the plantarolateral approach, the horses and ponies were walked for 200 meters. Latex was found in the distal intertarsal joints of 19 of 73 tarsi (26% communication) at necropsy. In 3 tarsi, latex was also found in the proximal intertarsal and tar-socrural joints.     

Effects of Bedding Material on the Lying Behavior in Stabled Horses

The objective of this study was to investigate the effect of straw, sawdust, coconut husk (husk), and coconut fiber (fiber) on the welfare of stable horses by observing their resting behavior. Twenty horses with ages ranging from 3 to 21 years were used at the Equine Research Institute of the Japan Racing Association, Utsunomiya, Japan. Five horses were allocated to each bedding condition. The behavior of each horse was recorded by video camera for 3 days and was continuously sampled from 17:00 to 05:00. The total duration, the number of bouts, and the mean and the maximum duration of bouts in standing rest, sternal lying, and lateral lying were calculated and analysed by the Kruskal-Wallis test and post hoc Steel-Dwass test. There was no difference in the standing rest and the sternal lying among beddings. Significant differences were observed in these values in the lateral lying among the different beddings (P<0.05). The values of the means of the total duration, the number of bouts, and the mean and the maximum duration of bout in the lateral lying were greater when husk was used as the bedding material than when sawdust were used (P<0.05). The results of the observations show that the new bedding materials would be as usable as straw. However, lateral lying was observed less frequently when sawdust were used as bedding; this indicates that use of sawdust as bedding material will decrease the welfare of stabled horses.     

Responses of Guinea-Pig Lung Parenchymal Strips to Tracheobronchial Lavage Fluid from Horses affected with Summer Pasture-Associated Obstructive Pulmonary Disease

The response of parenchymal strips from guinea-pig lungs to tracheobronchial lavage fluid (TBLF) collected from 8 normal horses and from 8 affected with summer pasture-associated obstructive pulmonary disease (SPAOPD) was determined. TBLF was collected during the summer (July) and winter (February) seasons. The serum/TBLF urea nitrogen ratio was used to standardize the mediator concentration in the TBLF. Four strips were used from each guinea-pig. The first strip did not receive any antagonist and served as the control. The second, third and fourth strips received antagonists of PGE2, LTD4 and PAF, respectively at 10–6 mol/L for 30 min. The tissues were then precontracted with a dose of histamine (10–5 mol/L) and their responses to 1 ml of TBLF were determined. The study showed that TBLF obtained in the summer from unaffected horses produced a significantly greater relaxation than that from the affected horses, whereas TBLF obtained in the winter from unaffected or affected horses did not cause a significantly different degree of relaxation. Among the antagonist-treated strips, only those exposed to the PGE2 blocker showed a significant reduction in the relaxation caused by TBLF obtained in the summer from SPAOPD horses. This suggests that PGE2 is an important mediator present in the summer in the TBLF from horses affected with SPAOPD.     

Transporting and Exercising Unconditioned Horses: Effects on Microflora Populations

The objective of this study was to determine if transportation and exercise stress in horses affect the microflora populations in the equine hindgut. Four horses were subjected to three transport periods (0, 3, and 6 hours) with a 7-d rest period between each transport. Horses were fed 0.91 kg/day of Purina Impact All Stages 12% and had ad libitum access to Cynodon dactylon (Coastal Bermudagrass) hay. Fecal samples were collected before (0 hours) and after (48 hours) transport. In addition, three horses underwent a different standardized exercise test with a 7-d rest period between each exercise. Standardized exercise test intensity was determined by heart rate to validate if the horse was in aerobic or anaerobic work. The protocol for fecal sample collection after exercise was the same as for transport. Prokaryotic community profiling was conducted by 16S metagenomic analysis. After DNA evaluation, differences were found in the microbiome at transport 0 hours and grouped transport 3 hours time 48 and transport 6 hours time 48 (PERMANOVA P = .037) where Bacteroidetes increased 48 hours after transport and Firmicutes decreased 48 hours after transport. Exercise microbial communities showed no difference in either alpha or beta diversity when compared with controls (0 hours). In the present study, difference in microflora may have resulted from stress duration of transport rather than stress duration of exercise.