Ex-vivo articular cartilage removal from equine proximal interphalangeal joints using cannulated drill bits

OBJECTIVE

This report evaluates the use of 4.5- and 5.5-mm cannulated drill bits for articular cartilage removal from the proximal interphalangeal joints of equine cadaver limbs.

ANIMALS

Limbs from 8 equine cadavers, all with normal proximal interphalangeal joints.

PROCEDURE

Proximal interphalangeal joints of 32 limbs from 8 equine cadavers were drilled using either 4.5- or 5.5-mm cannulated drill bits. Pastern joints were then disarticulated, and intra-articular drilling was evaluated by visual inspection.

RESULTS

Post-drilling evaluation revealed complete intra-articular drilling occurred in all 32 joints.

CONCLUSION

Canulated 4.5- and 5.5-mm drill bits resulted in consistent accurate intra-articular drilling in the proximal interphalangeal joint of horses.

CLINICAL RELEVANCE

Cannulated drill bits provided an effective and consistent modality for articular cartilage removal with potential for improved accuracy of articular drilling and applications in minimally invasive proximal interphalangeal joint arthrodesis.

Treatment of temporohyoid osteoarthropathy in horses with a basihyoid-ceratohyoid disarticulation technique: 6 cases (2018-2019)

OBJECTIVE

To describe a technique for basihyoid-ceratohyoid disarticulation (BCD) in standing sedated horses affected by temporohyoid osteoarthropathy (THO) and report outcomes for horses that underwent the procedure.

ANIMALS

6 client-owned horses.

PROCEDURES

Electronic medical records of a veterinary teaching hospital were searched to identify horses that underwent BCD for treatment of THO from 2018 to 2019. Signalment, clinical data, use of the horse, and complications were recorded. Follow-up data obtained by telephone interview with owners included the clinical outcome and time to improvement after surgery, any persistent clinical signs, horse's activity level before onset of clinical signs and after BCD, subsequent use of the horse, and whether they would pursue the same treatment again.

RESULTS

All horses tolerated the procedure well, with no complications and improved neurologic function after BCD. Five of 6 horses had a reported activity level equal to or greater than that prior to having signs of THO. Three of 3 horses with acute ataxia prior to BCD reportedly had full resolution of this sign; 3 of 4 horses with facial nerve deficits prior to BCD had mild residual facial nerve deficits at follow-up. All owners indicated they would pursue BCD again.

CONCLUSIONS AND CLINICAL RELEVANCE

The BCD procedure was performed safely in this sample of THO-affected horses that were sedated while standing, avoiding risks associated with general anesthesia and resulting in no adverse effects such as iatrogenic injury to neurovascular structures.

Effects of head position on internal and external carotid pressures in standing sedated horses

The effects of head position on internal carotid artery (ICA) and external carotid artery (ECA) pressures in standing sedated horses were evaluated in this study. The common carotid artery (CCA) was catheterized in 6 horses using an ultrasound-guided technique to facilitate placement of a pressure transducer within the ICA and ECA at the level of the guttural pouch. Transducer position was confirmed by endoscopic visualization. Mean arterial pressure (MAP) was measured with horses in both a head-up and head-down position. The dorsal metatarsal artery was catheterized as a control. Maintaining a head-up position decreased MAP in both the ICA (median: 75.21 mmHg) and ECA (median: 79.43 mmHg), relative to the head-down position (ICA median: 104.65 mmHg; ECA median: 102.26 mmHg). Mean arterial pressure in the dorsal metatarsal artery was not affected by head position. The head-up position resulted in lower arterial pressures in both the ICA and ECA (P = 0.03) compared with the head-down position in standing sedated horses.

The Use of Pneumatic Impact Lithotripsy in a Laparoscopic Retrieval Pouch for Removal of Large Cystoliths in Two Female Horses

Two mares, aged 15 and 21 years, were examined because of urinary incontinence, intermittent hematuria, and urine scalding. On admission of both horses, physical parameters were within normal limits and urine scalding of the skin at the ventral perineum was noted. Transrectal palpation and cystoscopy revealed a large type I cystolith (>10 cm) with associated hyperemia and focal ulceration of the bladder mucosa. In horse 1, hemogram, serum biochemical analysis, and renal ultrasound were not performed because of owner finances. In horse 2, results from hematological and serum biochemical analysis were unremarkable and renal ultrasonography did not reveal any abnormalities. Pneumatic impact lithotripsy in a laparoscopic retrieval pouch was performed under cystoscopic guidance after caudal epidural anesthesia, with the horses standing and under sedation. A laparoscopic retrieval device was passed alongside a flexible endoscope into the urinary bladder and the cystolith was manipulated into the pouch. A customized single stainless-steel rod scaler attached to an air compressor was used for fragmentation of the cystolith contained within the retrieval pouch. Lithotripsy time was 42 minutes for horse 1 and 31 minutes for horse 2. Both horses were released from hospital the day of surgery. Both horses were continent and voided normal streams of urine for the duration of the follow-up periods of 27 and 19 months for horse 1 and horse 2, respectively. Pneumatic impact lithotripsy in a laparoscopic retrieval pouch provided a time-efficient and minimally invasive surgical treatment option for removal of large cystoliths in mares.

A Standing Percutaneous Technique for Proximal Interphalangeal Joint Arthrodesis in Twelve Horses (2014-2017)

OBJECTIVES

 This report describes the use of a minimally invasive standing pastern arthrodesis technique for the treatment of osteoarthritis in horses and documents its clinical outcome in 12 horses.

MATERIALS AND METHODS

 Medical records and radiographs of horses diagnosed with proximal interphalangeal joint osteoarthritis that underwent standing pastern arthrodesis using transarticular screws were reviewed. Follow-up information for determination of outcome was obtained via phone interview with the owners.

RESULTS

 Twelve horses (15 limbs) were included in the study. Radiographical findings revealed severe osteoarthritis in 12/15 limbs and moderate osteoarthritis in 3/15 limbs. Follow-up information was available for 11/12 cases (13/15 limbs). Phone surveys with the owners revealed that 8/11 horses were performing at their previous activity level or higher. Two horses remained lame. One horse developed a surgical site infection and was euthanatized. The average time for horses to return to their previous level of activity was 6.5 months (range: 1-18 months).

CLINICAL SIGNIFICANCE

 Stabilization of the proximal interphalangeal joint in horses with moderate-to-severe osteoarthritis can be performed using this minimally invasive standing technique. This procedure can be performed safely and provides a similar outcome when compared with other described techniques.

Comparison of incisional bursting strength of 2-strand continuous crossing and simple continuous patterns for closure of the equine linea alba

The objective of this study was to assess and compare the bursting pressure and mode of failure of a 2-strand continuous crossing suture pattern and a simple continuous suture pattern for closure of the equine linea alba. No difference in bursting strength or mode of failure was found between the 2 suture patterns.

Morcellation for testes extraction in horses undergoing standing laparoscopic cryptorchidectomy

The major objective of this study was to describe the use of morcellation for standing laparoscopic cryptorchidectomy in 30 client-owned horses. A second objective was to describe a laparoscopic-assisted standing scrotal technique for removal of a descended testis in unilateral cryptorchids. Morcellation for extraction of abdominal testes is effective, efficient, and well-tolerated. Morcellation enabled safe and straightforward extraction of testes from the abdomen through an approximately 13- to 20-mm incision using a 2-portal technique. No incisional or morcellator-related complications occurred. Our laparoscopic-assisted standing scrotal technique for removal of a descended testis in unilateral cryptorchids entails intra-abdominal sealing and transection of the spermatic cord under laparoscopic viewing and subsequent removal of the testis through a scrotal incision. This technique enabled the surgeon to confirm hemostasis after transection of the spermatic cord and allowed tension-free removal of the descended testis. No intra-operative or incisional complications were encountered.

Emerging asymmetric interactions between forage and predator fisheries impose management trade-offs

A size and trait-based marine community model was used to investigate interactions, with potential implications for yields, when a fishery targeting forage fish species (whose main adult diet is zooplankton) co-occurs with a fishery targeting larger-sized predator species. Predicted effects on the size structure of the fish community, growth and recruitment of fishes, and yield from the fisheries were used to identify management trade-offs among the different fisheries. Results showed that moderate fishing on forage fishes imposed only small effects on predator fisheries, whereas predator fisheries could enhance yield from forage fisheries under some circumstances.

Telephone communication in emergency cases: a training program for veterinary students

The purpose of this project was to evaluate the incorporation of a telephone communication exercise into the junior surgery laboratory at Washington State University. Subjectively, the communication component seemed to encourage greater student preparedness and participation or ownership of cases in the surgical laboratory. Simulated clients were asked to score students on specific tasks and give any specific feedback. Students evaluated themselves on identical material. Areas of communication most likely to result in disparity of scores between the client's evaluation and the student's self-assessment were related to the patient's aftercare. Student survey results were consistently positive in regard to the value of the telephone communications exercise. Communication training in the veterinary curriculum could benefit from identifying opportunities to further integrate client communication experiences into other courses or laboratory experiences.

Comparison of endotracheal intubation techniques in llamas

This study evaluated a retrograde orotracheal intubation technique and compared it to the traditional normograde intubation technique used in llamas. Oral anatomical features, which can impair visualization of the epiglottis and laryngeal structures, and the production of excessive salivary secretions make it difficult to establish an airway under emergency conditions. Normograde intubation involves placing a stylet through the mouth into the trachea and advancing the endotracheal tube over the stylet into the trachea. For retrograde intubation, a nested trochar with cannula is placed into the cervical trachea and a stylet is advanced through the cannula and out the mouth. The endotracheal tube is advanced over the stylet back into the trachea. Our evaluation of both techniques found no statistical difference in time to place the stylet or endotracheal tube; however, fewer attempts were needed to place the tube using the retrograde technique. We found the retrograde technique to be a viable option for intubating llamas.

INJURY OF THE COLLATERAL LIGAMENTS OF THE DISTAL INTERPHALANGEAL JOINT DIAGNOSED BY MAGNETIC RESONANCE

We describe the clinical, imaging, and necropsy findings of two horses with severe injury of the collateral ligaments of the distal interphalangeal (DIP) joint diagnosed using magnetic resonance (MR) imaging. In MR images it was possible to examine the collateral ligaments of the DIP joint from the origin at the middle phalanx to the insertion on the distal phalanx. Both horses in this report had abnormal high signal intensity within the collateral ligaments of the DIP joint, and one horse had abnormal high signal intensity within the bone of the distal phalanx on short tau inversion recovery (STIR) and T2-weighted imaging sequences. High signal intensity on STIR and T2-weighted images represents abnormal fluid accumulation indicative of inflammation, within ligament, tendon, or bone on these imaging sequences. Abnormalities were confirmed on necropsy in both horses. Injury of the collateral ligaments of the DIP joint should be considered as a source of pain in horses with lameness localized to the foot.

Evaluation of Arthrocentesis Site Bacterial Flora before and after 4 Methods of Preparation in Horses with and without Evidence of Skin Contamination

OBJECTIVE

To evaluate the effectiveness of four methods of povidone-iodine preparation on skin bacterial flora of arthrocentesis sites, in horses, with and without evidence of skin contamination.

STUDY DESIGN

Prospective randomized study.

ANIMALS

Twenty-four adult horses.

METHODS

Horses were assigned to either the clean or contaminated group based on housing environment and visual evidence of contamination. Using a moist sterile swab, microbial culture samples were obtained from the skin over the distal interphalangeal joints immediately before and after preparation. Each site was aseptically prepared with 1 of 4 povidone-iodine techniques: 10-minutes scrub, 5-minutes scrub, three 30-second scrubs, or commercial one-step iodophor surgical solution. Colony forming units (CFUs) were determined for each sample, 24 hours after inoculation, on blood agar plates.

RESULTS

Mean (+/-SD) pre-scrub CFUs/mL was significantly higher in the contaminated group (9588.33+/-1223.65) compared with the clean group (4489.00+/-3842.03) (P<.01). After preparation of the arthrocentesis sites, there were no significant differences in post-scrub CFUs/mL among the 10 minutes (mean clean, 46.00+/-64.36; mean contaminated, 28.67+/-18.04), 5 minutes (mean clean, 84.17+/-109.80; mean contaminated, 40.33+/-44.52), three 30 seconds povidone-iodine scrubs (mean clean, 95.50+/-172.29; mean contaminated, 46.67+/-56.94), or application of a commercial one-step iodophor surgical solution (mean clean, 102.17+/-161.78; mean contaminated 117.67+/-143.78); or between the clean (81.96+/-131.69) and contaminated groups (58.33+/-85.90) (P<.01).

CONCLUSIONS

Preparation of the distal interphalangeal joint arthrocentesis site with each of these techniques significantly reduces the bacterial flora to a similar level for arthrocentesis in horses with and without evidence of skin contamination. Clinical Relevance- Aseptic preparation of the skin over the distal interphalangeal joint may be accomplished with any of these techniques.

Use of magnetic resonance imaging for identifying subchondral bone damage in horses: 11 cases (1999-2003)

OBJECTIVE

To assess the use of magnetic resonance (MR) imaging for identifying subchondral bone damage in the distal limbs of horses.

DESIGN

Retrospective study.

ANIMALS

11 horses.

PROCEDURE

Medical records of horses with lameness and subsequent evidence of subchondral bone damage as determined by MR imaging were reviewed. Severity and duration of lameness, results of diagnostic local anesthesia and diagnostic testing, surgical and necropsy findings, and treatment were recorded. Outcome was determined by follow-up information obtained from the owner or referring veterinarian.

RESULTS

Lameness was localized by physical examination and diagnostic local anesthesia. Lameness was localized to the metacarpophalangeal or metatarsophalangeal joint in 4 horses, distal interphalangeal joint in 5 horses, and tarsocrural joint in 2 horses. The duration of lameness ranged from 2 weeks to 20 months. Magnetic resonance imaging of the affected joints revealed abnormal fluid accumulation within the subchondral bone. None of the abnormalities observed by MR imaging were detected by radiography. Subchondral bone damage was diagnosed in all horses. Arthroscopy of the affected joint was performed in 4 horses. Communication with the articular surface of the affected bone was suspected on the basis of results of MR imaging in 4 horses and was confirmed by arthroscopy in 1 horse and by necropsy in 1 horse.

CONCLUSIONS AND CLINICAL RELEVANCE

Magnetic resonance imaging was useful for providing a diagnosis when other imaging techniques did not definitively identify the cause of lameness. Subchondral bone damage was clearly identified by MR imaging and should be considered as a cause of lameness in horses in which radiographic findings are unremarkable.

The effect of implanting gentamicin-impregnated polymethylmethacrylate beads in the tarsocrural joint of the horse

OBJECTIVE

To determine the effect of intra-articular gentamicin-impregnated polymethylmethacrylate (PMMA) beads inserted in the equine tarsocrural joint on the synovial fluid, synovial lining, and cartilage, and to determine the peak and sustainable gentamicin concentrations in synovial fluid and plasma.

STUDY DESIGN

Pharmacokinetic, cytologic, and histologic study of the effect of gentamicin-impregnated PMMA on normal equine tarsocrural joints.

ANIMALS

Five healthy adult horses.

METHODS

Gentamicin-impregnated PMMA bead strands (3 strands each of 40 beads, with each strand containing 100 mg gentamicin) were surgically inserted into one radiographically normal tarsocrural joint in 5 horses. Each horse had both joints flushed with 1 L of lactated Ringer's solution before bead administration. Synovial fluid total protein concentration, white blood cell (WBC) count, gentamicin concentration, synovial histology, cartilage integrity, and cartilage glycosaminoglycan (GAG) concentrations were determined.

RESULTS

Gentamicin concentration (mean +/- SEM peak concentration, 27.9 +/- 2.27 microg/mL) occurred in the first 24 hours and remained above 2 microg/mL for 9 days. Gentamicin concentrations in control joints and the plasma remained below detectable levels. The synovial fluid WBC count for treated joints was increased compared with control joints for 72 hours, but was similar at day 6. The synovial protein concentration in gentamicin-treated joints remained increased for 21 days. Synovium in treated joints had diffuse synovitis, whereas control joints had less fibrovascular proliferation. Superficial cartilage erosion was present in all treated joints. There was no difference in the GAG content of treated and control joint cartilage.

CONCLUSIONS

Short-term implantation of gentamicin (300 mg)-impregnated PMMA beads can provide therapeutic levels of gentamicin (>2 microg/mL) in the normal tarsocrural joint for 9 days; however, gentamicin-impregnated PMMA beads induce synovitis and superficial cartilage erosion.

CLINICAL RELEVANCE

Temporary intra-articular administration of antibiotic-impregnated PMMA may be an effective way to treat septic joints that require constant high concentrations of antibiotics.

Animal group forces resulting from predator avoidance and competition minimization

A new model to explain animal spacing, based on a trade-off between foraging efficiency and predation risk, is derived from biological principles. The model is able to explain not only the general tendency for animal groups to form, but some of the attributes of real groups. These include the independence of mean animal spacing from group population, the observed variation of animal spacing with resource availability and also with the probability of predation, and the decline in group stability with group size. The appearance of "neutral zones" within which animals are not motivated to adjust their relative positions is also explained. The model assumes that animals try to minimize a cost potential combining the loss of intake rate due to foraging interference and the risk from exposure to predators. The cost potential describes a hypothetical field giving rise to apparent attractive and repulsive forces between animals. Biologically based functions are given for the decline in interference cost and increase in the cost of predation risk with increasing animal separation. Predation risk is calculated from the probabilities of predator attack and predator detection as they vary with distance. Using example functions for these probabilities and foraging interference, we calculate the minimum cost potential for regular lattice arrangements of animals before generalizing to finite-sized groups and random arrangements of animals, showing optimal geometries in each case and describing how potentials vary with animal spacing. Copyright 1999 Academic Press.