Adrenocorticotropin-containing neoplastic cells in a pars intermedia adenoma in a horse

Pituitary-dependent hyperadrenocorticism was diagnosed in a 14-year-old Arabian mare with chronic weight loss, hirsutism, polyuria, and polydipsia. The mare had a stress leukogram, glucosuria, and consistent hyperglycemia. Plasma glucose concentrations were resistant to suppression by insulin. Plasma cortisol concentrations were within normal limits, but did not respond to dexamethasone suppression and had an exaggerated response to ACTH stimulation. At necropsy, a chromophobe adenoma of the pars intermedia of the pituitary gland was found. The zona fasciculata of the adrenal cortex and the pancreatic islets of Langerhans were hypertrophied. An immunohistologic staining technique was used to demonstrate ACTH-containing neoplastic cells in the pituitary mass. These cells released ACTH and other peptides that initiated the chain of endocrinologic events leading to clinical disease.     

Bilateral renal dysplasia with nephron hypoplasia in a foal

Bilateral renal dysplasia and nephron hypoplasia was diagnosed in a Quarter Horse foal with clinical signs of lethargy, convulsions, and diarrhea. Laboratory evaluation revealed anemia, hypoproteinemia, leukopenia, hyponatremia, hypochloremia, and hyposmolality. The foal also had high concentrations of serum creatinine, BUN, and phosphorus. Evaluation of urinary indices revealed a high ratio of urinary gamma-glutamyl-transferase activity to concentration of creatinine, as well as a high fractional clearance ratio of sodium and potassium. Intravenous treatment with saline solution (0.9% NaCl) and antimicrobials provided only temporary resolution of some of the abnormalities. Diagnosis was partly established by histologic evaluation of renal tissue obtained via an ultrasonographically guided biopsy and was confirmed at necropsy. Pathologic changes in the kidney were unique in that the size of the kidneys, along with the appearance and number of glomeruli, were essentially normal despite marked hypoplasia of nephron tubules in the medulla.     

A large cyst in the distal femur of a horse

A 10-year-old Warmblood gelding presented with a left hindlimb lameness. Diagnostic analgesia located the lameness to the stifle. Radiography showed an unusually large cyst in the distal femur. Diagnostic arthroscopy of the stifle did not reveal any significant abnormalities. An extra-articular transcortical approach to the cyst was performed for drainage, curettage, and provision of an autologous, cancellous bone graft, gentamicin-impregnated collagen fleeces and injectable steroid. The horse returned to a higher level of competitive dressage than prior to surgery. This report describes a large cyst in the distal femur of a horse.     

Pyelonephritis associated with renal failure in a horse

A 20-year-old gelding with weight loss and generalized weakness that progressed gradually over a 3-month period was diagnosed as having pyelonephritis caused by Staphylococcus aureus infection. Abnormal laboratory findings included high values for BUN, creatinine, potassium, and calcium, and depletion of sodium. Determination of glomerular filtration rate and effective renal plasma flow indicated a severe decrease in renal filtration and perfusion.     

Management of a transverse fracture in the distal phalanx of a horse.

A yearling horse was presented with a septic, transverse fracture in the frontal plane of the distal phalanx. The fracture fragment was surgically removed from the parent bone via the sole. The foot was managed by corrective farriery and the horse was able to be ridden for pleasure.     

Fractures of the distal phalanx in the horse

Fractures of the distal phalanx are an important cause of lameness referrable to the foot. Depending on the fracture configuration and articular involvement, conservative or surgical treatment may be required. Fractures of the distal phalanx have been divided into six categories based on fracture configuration. Discussion of clinical features, management, and prognosis for horses with distal phalangeal fractures is presented for each fracture type.     

Prolonged, continuous distal limb cryotherapy in the horse

REASONS FOR PERFORMING STUDY: The recommended duration of cryotherapy in horses is currently extrapolated from human medicine. Prolonged, continuous cryotherapy (days rather than minutes) may be of therapeutic value if it is safe and well tolerated. OBJECTIVES: To evaluate the effect of prolonged, continuous application of ice and water to the equine distal limb. METHODS: A slurry of ice and water was applied to the right forelimb of 4 Standardbred horses for 48 h. Hoof temperature, ambient temperature and ice boot temperature were logged continuously and clinical observations recorded every 2 h. Lameness examinations were performed prior to application and 1 week, 6 months and 1 year after removal of the ice boot. RESULTS: Continuous cryotherapy was well tolerated and resulted in marked cooling of the treated foot. No significant variation in clinical parameters was noted, and no lameness or gross pathology noted in the treated limbs at any examination period. CONCLUSIONS: The continuous application of ice and water is a safe and effective means of cooling the equine distal limb. The extremely low, constant temperatures achieved may be of benefit in the management of various distal limb conditions. POTENTIAL RELEVANCE: Providing clinicians and research workers with a potent therapeutic/prophylactic modality for disorders of the equine distal limb.     

Clinical course of renal adenocarcinoma associated with hypercupraemia in a horse

A four-year-old shire mare with haematuria, colic, terminal weight loss and an abdominal mass had a large unilateral renal adenocarcinoma. Clinical signs were monitored for 11 months. Increased serum copper concentrations were measured on two occasions. Hypercupraemia is discussed as a possible paraneoplastic change.     

Use of magnetic resonance imaging to diagnose distal sesamoid bone injury in a horse

CASE DESCRIPTION: A 5-year-old Appaloosa mare was examined for severe left forelimb lameness of 4 months' duration. CLINICAL FINDINGS: Lameness was evident at the walk and trot and was exacerbated when the horse circled to the left. Signs of pain were elicited in response to hoof testers placed over the frog of the left front hoof, and a palmar digital nerve block eliminated the lameness. Radiographs revealed no abnormalities, but magnetic resonance imaging (MRI) revealed increased bone density in the medullary cavity of the distal sesamoid (navicular) bone in the proton density and T2-weighted images and a defect in the fibrocartilage and subchondral bone of the flexor cortex. TREATMENT AND OUTCOME: Because of the absence of improvement after 4 months and the poor prognosis for return to soundness, the mare was euthanatized. An adhesion between the deep digital flexor tendon and the flexor cortex defect on the navicular bone was grossly evident, and histologic evaluation revealed diffuse replacement of marrow trabecular bone with compact lamellar bone. Changes were consistent with blunt traumatic injury to the navicular bone that resulted in bone proliferation in the medullary cavity. CLINICAL RELEVANCE: Use of MRI enabled detection of changes that were not radiographically evident and enabled accurate diagnosis of the cause of lameness. Navicular bone injury may occur without fracture and should be considered as a differential diagnosis in horses with an acute onset of severe unilateral forelimb lameness originating from the heel portion of the foot.     

Treatment of a subchondral cystic-like lesion in the distal scapula with a translesional bone screw in a horse

A 2-year-old French Warmblood stallion was presented for lameness investigation. The diagnostic procedures identified the reason for lameness as being a subchondral cystic-like lesion (SCL) in the glenoid cavity of the scapula. The horse was surgically treated with a translesional 4.5 mm cortical bone screw inserted through the SCL under radiographic guidance. Sixty days after surgery, the horse was sound and the SCL showed significant radiographic signs of healing. Radiographs obtained 180 days after surgery showed further radiographic healing, with the SCL presenting a radiodensity similar to the surrounding bone. At 4 years post-operative follow-up, the horse is sound and competing successfully as a 6-year-old in Concours de Saut International (CSI) competitions.     

Ultrasonographic examination of the caudal structures of the distal antebrachium in the horse

Evaluation of the caudal distal antebrachium using ultrasound is a very useful diagnostic procedure for identification of soft tissue abnormalities in flexor structures of the equine limb. In this article we describe how ultrasonographic imaging may be used to complement radiography of the carpus in evaluating horses that present with peri‐carpal swelling and/or lameness localised to the carpal region. Ultrasonographic examination assists with the identification or exclusion of significant injuries to muscular, tendonous and ligamentous structures within the distal antebrachium and enables practitioners to proceed with appropriate therapeutic and rehabilitation plans for the immediate benefit for their patients while also recognising pathology that could progress to cause long‐term, chronic lameness issues without aggressive and effective intervention.