Objective—To investigate gene expression of the major proteolytic systems and growth regulators in skeletal muscle of horses with myopathy associated with pituitary pars intermedia dysfunction (PPID).
Animals—14 horses with PPID-associated myopathy and 7 healthy control horses.
Procedures—Horses with PPID and controls were age matched (15 to 28 years old). Muscle biopsy specimens were collected from both groups and processed for RNA and cDNA extraction. Validation of the most stable housekeeping genes for skeletal muscle was performed and used to compare gene expression of the following proteolytic systems: cysteine aspartate protease–dependent systems (caspases), lysosomal-dependent systems (cathepsins), non–lysosomal calcium protease–dependent systems (calpains), and ubiquitin-proteasome–dependent systems (ubiquitins). Gene expression of negative regulators of muscle growth (myostatin and inflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α) was also determined.
Results—No significant difference between groups was detected in expression of the major proteolytic systems except for m-calpain, which was greater in horses with PPID. No differences in gene expression of myostatin and interleukin-1β, interleukin-6, and tumor necrosis factor-α were detected between groups.
Conclusions and Clinical Relevance—Greater expression of m-calpain may suggest that calpains play an important role in development of muscle atrophy in horses with PPID. However, because posttranslational events may alter protein activation, inactivation, and functions not studied here, other mechanisms of muscle atrophy cannot be excluded.
OBJECTIVE To compare clinical findings and short-term outcome for horses with intestinal entrapment in the gastrosplenic ligament (GLE) with those of horses with intestinal entrapment in the epiploic foramen (EFE).
DESIGN Retrospective case-control study.
ANIMALS 43 horses with GLE (cases) and 73 horses with EFE (controls).
PROCEDURES Medical records of horses examined because of colic at a veterinary teaching hospital between 1992 and 2012 were reviewed. Signalment was extracted from medical records for all horses with colic (colic population), and additional information regarding colic history, clinical findings, treatments, and outcome was extracted from the records of horses in which GLE or EFE was diagnosed during surgery or necropsy. Signalment was compared between the colic population and the case and control populations. Clinical findings and short-term outcome were compared between the cases and controls.
RESULTS The proportions of middle-aged horses and geldings in both the case and control groups were greater than those in the colic population. Mean heart rate and blood and peritoneal fluid lactate concentrations in horses with EFE were significantly greater than those for horses with GLE. The proportion of horses that underwent surgery and were discharged from the hospital (short-term survival rate) did not differ between the GLE (22/25 [88%]) and EFE (29/34 [85%]) groups.
CONCLUSIONS AND CLINICAL RELEVANCE Compared with the colic population, results suggested middle-aged geldings might be predisposed to GLE and EFE. The short-term survival rate was similar between the GLE and EFE groups even though horses with EFE had more severe systemic derangements than did horses with GLE.
To assess the diagnostic value of plasma and peritoneal fluid procalcitonin concentrations for identification of horses with strangulating intestinal lesions.
65 horses with signs of colic of intestinal origin and 10 healthy (control) horses.
For each horse, plasma and peritoneal fluid samples were obtained for a CBC and determination of total protein, procalcitonin, and lactate concentrations. Signalment and clinicopathologic findings were compared among control horses and horses with strangulating and nonstrangulating intestinal lesions.
Mean ± SD plasma (274.9 ± 150.8 pg/mL) and peritoneal fluid (277 ± 50.6 pg/mL) procalcitonin concentrations for horses with colic were significantly greater than the mean ± SD plasma (175.5 ± 46.0 pg/mL) and peritoneal fluid (218.8 ± 48.7 pg/mL) procalcitonin concentrations for control horses. Mean procalcitonin concentration in peritoneal fluid, but not plasma, differed significantly between horses with strangulating lesions and those with nonstrangulating lesions. A peritoneal fluid procalcitonin concentration ≥ 281.7 pg/mL had a sensitivity of 81%, specificity of 69%, positive predictive value of 56.7%, and negative predictive value of 87.9% for detection of strangulating lesions.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that peritoneal fluid procalcitonin concentration, when evaluated in conjunction with other clinicopathologic results, might be a sensitive indicator of intestinal ischemia and facilitate early identification of horses that require surgery to address a strangulating lesion.
OBJECTIVE To evaluate the use of a laparoscopic specimen retrieval pouch for removal of intact or fragmented cystic calculi from standing horses.
DESIGN Retrospective case series.
ANIMALS 8 horses (5 geldings and 3 mares) with cystic calculi.
PROCEDURES Physical examination and cystoscopic, ultrasonographic, and hematologic evaluations of urinary tract function were performed for each horse. A diagnosis of cystic calculus was made on the basis of results of cystoscopy and ultrasonography. Concurrent urolithiasis or other urinary tract abnormalities identified during preoperative evaluation were recorded. Horses were sedated and placed in standing stocks, and the perineum was aseptically prepared. Direct access to the urinary bladder was gained in geldings via perineal urethrotomy or in mares by a transurethral approach. Calculi were visualized endoscopically, manipulated into the retrieval pouch, and removed intact or fragmented (for larger calculi).
RESULTS For 4 geldings and 1 mare, fragmentation was necessary to facilitate calculus removal. Mean duration of surgery was 125 minutes, and trauma to the urinary bladder and urethra was limited to areas of hyperemia and submucosal petechiation. No postoperative complications were encountered for any horse. When lithotripsy was required, the retrieval pouch provided an effective means of stabilizing calculi and containing the fragments for removal.
CONCLUSIONS AND CLINICAL RELEVANCE Use of the laparoscopic specimen retrieval pouch was an effective, minimally traumatic method for retrieving cystic calculi from standing horses. The pouch protected the urinary bladder and urethra from trauma during calculus removal and allowed for stabilization, containment, and fragmentation of calculi when necessary.
OBJECTIVE To assess incidence of incisional infection in horses following management with 1 of 3 protective dressings after exploratory celiotomy for treatment of acute signs of abdominal pain (ie, colic) and determine the risk of complications associated with each wound management approach.
DESIGN Prospective, randomized, controlled study.
ANIMALS 85 horses.
PROCEDURES Horses were assigned to 3 groups. After standardized abdominal closure, a sterile cotton towel (group 1) or polyhexamethylene biguanide–impregnated dressing (group 2) was secured over the incision site with 4 or 5 cruciate sutures of nonabsorbable monofilament, or sterile gauze was placed over the site and secured with an iodine-impregnated adhesive drape (group 3). Demographic and clinicopathologic data, intraoperative and postoperative variables, and development of complications were recorded and compared among groups by statistical methods. Follow-up information was collected 30 and 90 days after surgery. Incidence and odds of incisional complications were calculated.
RESULTS 75 horses completed the study. Group 3 typically had dressing displacement necessitating removal during anesthetic recovery; dressings were in place for a mean of 44 and 31 hours for groups 1 and 2, respectively. Purulent or persistent serosanguinous incisional discharge (ie, infection) was detected in 11 of 75 (15%) horses (2/24, 0/26, and 9/25 from groups 1, 2, and 3, respectively). Odds of incisional complications were significantly greater for group 3 than for groups 1 or 2.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that risk of infection after celiotomy for treatment of colic is lower for incisions covered with sterile towels or polyhexamethylene biguanide–impregnated dressings secured with sutures than for incisions covered with gauze secured with iodine-impregnated adhesive drapes.
Objective—To evaluate clinical findings, underlying causes, and short-term outcome associated with hemoperitoneum in horses.
Design—Retrospective case series.
Animals—67 horses with hemoperitoneum.
Procedures—Medical records of horses with hemo-peritoneum (excluding postoperative abdominal hemorrhage) from 1989 through 2004 were analyzed. Information obtained included history, signalment, physical examination findings, diagnostic test results, and short-term outcome.
Results—Breed distribution was 28 Thoroughbreds, 13 Arabians, 10 Quarter Horses, 5 Warmbloods, 3 Appaloosas, and 1 each of 8 other breeds. There were 40 mares, 23 geldings, and 4 stallions. Median age was 12 years (range, 1 month to 40 years). Signs of abdominal discomfort were the primary complaint in 79% of horses. Clinical findings included shock (60%) and pale mucous membranes (60%). Median heart rate was 76 beats/min (range, 30 to 216 beats/min), median respiratory rate was 30 breaths/min (range, 8 to 92 breaths/min), median Hct was 31% (range, 10.5% to 73.0%), and total protein concentration was 5.8 g/dL (range, 3.3 to 8.7 g/dL). Cause of hemoperitoneum was attributed to trauma (25.4%), neoplasia (17.9%), uterine artery rupture (13.4%), mesenteric injury (11.9%), disseminated intravascular coagulopathy (6.0%), other causes (3.0%), and idiopathic causes (22.4%). Fifty-one percent of horses survived to hospital discharge, 37% were euthanized, and 12% died. Poor short-term outcome was significantly associated with high respiratory rate and certain underlying causes.
Conclusions and Clinical Relevance—Hemoperitoneum is an infrequent but important cause of abdominal discomfort in horses. Predominant underlying causes were trauma, neoplasia, and idiopathic causes. Identification of underlying cause is important because of its association with outcome.
OBJECTIVE To determine the maximum concentration (Cmax) of amikacin and time to Cmax (Tmax) in the distal interphalangeal (DIP) joint in horses after IV regional limb perfusion (IVRLP) by use of the cephalic vein.
ANIMALS 9 adult horses.
PROCEDURES Horses were sedated and restrained in a standing position and then subjected to IVRLP (2 g of amikacin sulfate diluted to 60 mL with saline [0.9% NaCl] solution) by use of the cephalic vein. A pneumatic tourniquet was placed 10 cm proximal to the accessory carpal bone. Perfusate was instilled with a peristaltic pump over a 3-minute period. Synovial fluid was collected from the DIP joint 5, 10, 15, 20, 25, and 30 minutes after IVRLP; the tourniquet was removed after the 20-minute sample was collected. Blood samples were collected from the jugular vein 5, 10, 15, 19, 21, 25, and 30 minutes after IVRLP. Amikacin was quantified with a fluorescence polarization immunoassay. Median Cmax of amikacin and Tmax in the DIP joint were determined.
RESULTS 2 horses were excluded because an insufficient volume of synovial fluid was collected. Median Cmax for the DIP joint was 600 μg/mL (range, 37 to 2,420 μg/mL). Median Tmax for the DIP joint was 15 minutes.
CONCLUSIONS AND CLINICAL RELEVANCE Tmax of amikacin was 15 minutes after IVRLP in horses and Cmax did not increase > 15 minutes after IVRLP despite maintenance of the tourniquet. Application of a tourniquet for 15 minutes should be sufficient for completion of IVRLP when attempting to achieve an adequate concentration of amikacin in the synovial fluid of the DIP joint.
To determine the median time to maximum concentration (tmax) of amikacin in the synovial fluid of the tarsocrural joint following IV regional limb perfusion (IVRLP) of the drug in a saphenous vein of horses.
7 healthy adult horses.
With each horse sedated and restrained in a standing position, a 10-cm-wide Esmarch tourniquet was applied to a randomly selected hind limb 10 cm proximal to the point of the tarsus. Amikacin sulfate (2 g diluted with saline [0.9% NaCl] solution to a volume of 60 mL) was instilled in the saphenous vein over 3 minutes with a peristaltic pump. Tarsocrural synovial fluid samples were collected at 5, 10, 15, 20, 25, and 30 minutes after completion of IVRLP. The tourniquet was removed after collection of the last sample. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median maximum amikacin concentration and tmax were determined.
1 horse was excluded from analysis because an insufficient volume of synovial fluid for evaluation was obtained at multiple times. The median maximum synovial fluid amikacin concentration was 450.5 μg/mL (range, 304.7 to 930.7 μg/mL), and median tmax was 25 minutes (range, 20 to 30 minutes). All horses had synovial fluid amikacin concentrations ≥ 160 μg/mL (therapeutic concentration for common equine pathogens) at 20 minutes after IVRLP.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that, in healthy horses, maintaining the tourniquet for 20 minutes after IVRLP of amikacin in a saphenous vein was sufficient to achieve therapeutic concentrations of amikacin in the tarsocrural joint.
Case Description—A 15-year-old Quarter Horse gelding and a 26-year-old Thoroughbred gelding were evaluated because of hematuria of 4 to 6 days' duration following prolonged oral administration of phenylbutazone.
Clinical Findings—The horses had received either treatment with phenylbutazone for 3 months or intermittent long-term phenylbutazone treatment prior to development of hematuria. Each horse was systemically stable but had orthopedic or neurologic problems. Clinicopathologic findings included normochromic normocytic anemia in both horses and hypoalbuminemia and high BUN concentration in 1 horse. In both horses, urinalysis revealed proteinuria and RBCs, but no evidence of WBCs or bacteria. Ulceration and hemorrhage of the urinary bladder with no evidence of uroliths were observed via cystoscopy. Gastric ulceration along the margo plicatus was observed via gastroscopy.
Treatment and Outcome—For each horse, phenylbutazone treatment was discontinued and a synthetic prostaglandin (misoprostol) was administered. The hematuria resolved, and results of a follow-up CBC, serum biochemical analysis, urinalysis, and cystoscopy 25 or 30 days after cessation of phenylbutazone treatment were unremarkable in both cases.
Clinical Relevance—Given the known adverse effects of NSAID treatment in several species, phenylbutazone and its metabolites were suspected to have caused ulceration of the urinary bladder, resulting in hematuria, in the 2 horses. A definitive cause of urinary bladder ulceration was not confirmed in these cases; however, resolution of ulceration after discontinuation of phenylbutazone treatment and administration of synthetic prostaglandins and exclusion of other causes suggested an association between phenylbutazone administration and ulcerative cystitis in these horses.
Objective—To determine effects of cisapride and 5-hydroxytryptamine (5-HT) on the jejunum of horses.
Sample Population—Jejunal muscle strips from 8
Procedure—Muscle strips were suspended in isolated
muscle baths. Isometric stress responses to 5-HT
and cisapride, with and without specific antagonists,
Results—Muscle strips incubated with atropine and
tetrodotoxin responded to 5-HT and cisapride with an
increase in contractile force. The 5-HT caused a concentration-dependent increase in contractile amplitude,
with a maximum response (Emax) of 1,151 ± 214
g/cm2 and a molar concentration that induces contractile
force equal to 50% of maximum response
(EC50) of 0.028 ± 0.002 µM. Prior incubation with the
5-HT2 antagonist ketanserin decreased the Emax (626
± 147 g/cm2) and potency (EC50, 0.307 ± 0.105 µM) of
5-HT. Prior incubation with the 5-HT3 antagonist tropisetron
decreased the efficacy (Emax, 894 ± 184
g/cm2) to 5-HT. Cisapride also caused a concentrationdependent
increase in contractile amplitude, with an
Emax of 331 ± 82 g/cm2 and an EC50 of 0.302 ± 0.122
µM. Prior incubation with ketanserin decreased the
Emax (55 ± 17 g/cm2) and potency (EC50, 0.520 ± 0.274
µM) of cisapride.
Conclusion and Clinical Relevance—Stimulatory
effects of 5-HT and cisapride on circular smooth muscle
of equine jejunum are mediated primarily through
a noncholinergic effect. The effects of 5-HT are mediated,
at least partially, by 5-HT2 and 5-HT3 receptors,
whereas the effects of cisapride are mediated primarily
by 5-HT2 receptors. This may impact treatment of
horses with postoperative ileus. (Am J Vet Res