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Summary This report describes a 4-month-old Quarter Horse filly with an ectopic ureter. The filly presented with signs of urinary incontinence, which had been present since birth. Computed tomography (CT) examination and cystoscopy confirmed a diagnosis of a unilateral ectopic ureter. A nephrectomy of the left kidney was performed and renal function was closely monitored post operatively. The filly was treated for abdominal chylous effusion as a post operative complication. The filly survived to discharge from the hospital, and maintained normal urinary function at 12 months post operatively.

Summary The case reported here describes a rare presentation of necrotising, emphysematous oesophagitis and gastritis in a horse presenting for signs of anorexia, dysphagia and ptyalism. Radiography of the retropharyngeal region revealed intramural gas within the cranial oesophagus. Further diagnostic evaluation supported an ante mortem diagnosis of emphysematous oesophagitis with concurrent septic pleuritis and peritonitis. Post mortem findings confirmed an emphysematous, necrotising oesophagitis and gastritis with a Clostridium sp. transmural infection. To our knowledge, this case describes the first recorded ante mortem diagnosis of emphysematous oesophagitis with concurrent gastritis in the horse.

Summary The immunotherapeutic efficacy of specific immune plasma was evaluated in pony foals infected experimentally with Rhodococcus equi. Viable R. equi were aerosolised into the right caudodorsal lung of 10 foals at seven days of age. Immune plasma, produced by repeated parenteral administration of viable R. equi to an adult donor gelding, was harvested and frozen. Group 1 (4 foals) and Group 2 (6 foals) foals received lactated Ringer's solution and immune plasma, respectively, at seven and nine days post infection. Clinical signs, haematological alterations, immune responses and thoracic radiographs were monitored throughout the study. All foals were destroyed and complete post mortem examinations were performed. All foals developed pneumonia as evidenced by clinical and radiographic alterations. Immune plasma had no significant effect on survival rate, length of survival, temperature response or peripheral blood concentrations of leucocytes, neutrophils or fibrinogen. Enzyme-linked immunosorbent assay values for R. equi-specific antibody and serum concentrations of IgG were significantly greater in Group 2 foals following treatment with immune plasma. Post mortem examination of three Group 1 and four Group 2 foals, destroyed because of terminal disease, revealed severe pyogranulomatous pneumonia. The two surviving Group 2 foals were free of gross pulmonary lesions and had minimal microscopic scar formation three months post infection; whereas the one surviving Group 1 foal had a large, encapsulated, caseonecrotic pulmonary mass three months post infection. This study demonstrates that the parenteral administration of R. equi immune plasma to foals seven days after experimental infection with R. equi does not alleviate the clinical signs nor alter the course of disease.

Summary Reasons for performing study: Prognosis of Rhodococcus equi pneumonia can be challenging because the course of the disease is often insidious and overt clinical signs are subtle. Early diagnosis is considered desirable because it may offer the chance of more successful implementation of treatment and, thereby, improved outcome. Serological tests have previously failed to be accurate for early detection or diagnosis. Measurement of serum amyloid A (SAA) prior to and at the time of clinical signs was therefore chosen in order to assess its potential clinical use. Objective: To determine whether SAA concentrations differentiate foals affected with R. equi pneumonia from unaffected foals, either prior to the onset of disease or at the time of onset of clinical signs. Hypothesis: SAA concentrations are significantly higher among foals that develop R. equi pneumonia than in foals from the same environment that remain clinically unaffected. Methods: Serum samples were obtained from 212 foals 7–14 days and 196 foals 21–28 days post partum, and from affected foals and age-matched controls at the time of onset of signs of pneumonia. SAA concentration was determined for each sample. Results: There were no significant differences between SAA concentrations of foals with R. equi and clinically unaffected foals during the 2 periods of examination or at the time of onset of clinical signs of R. equi pneumonia. Conclusions: Concentrations of SAA are variable among foals with R. equi pneumonia and cannot be used reliably either as an ancillary diagnostic tool or to screen for early detection of disease during the first month post partum. Potential relevance: Bimonthly monitoring concentration of SAA is not useful as a screening test for early detection of R. equi pneumonia and does not facilitate diagnosis of this disease when used according to the protocol of this study.

Summary Streptococcus equi ssp. equi infection in the horse, or strangles, commonly results in abscessation of the submandibular, submaxillary or retropharyngeal lymph nodes. Although this classical presentation of strangles is associated with a low mortality rate, complications and sequlae may worsen the prognosis and increase mortality rates. This article reviews sequelae and complictions of S. equi ssp. equi infection in the horse, including guttural pouch empyema, bastard strangles and immune mediated diseases such as purpura haemorrhagica, myopathies and myocarditis.

Summary The case reported here represents an atypical presentation of bastard strangles in an 18-year-old Arab mare. The horse initially presented for progressive neck pain characterised by reluctance to lateral and ventroflexion of the neck. Subsequent diagnostics revealed a subscapular abscess and aspirates of the mass cultured positive for Streptococcus equi ssp. equi. Surgical drainage and debridement of the abscess was performed under general anaesthesia. Six months post surgery, the mare had made a complete recovery.

Summary The case of a horse with a subchondral bone cyst in the lateral slope of the intermediate humeral tubercle is presented. Diagnosis was complicated by the unusual location and subsequent challenge in imaging the cyst. Endoscopic debridement resulted in a good outcome.

Summary A commercially available pulse oximeter was evaluated in anaesthetised foals to determine its accuracy for estimating arterial haemoglobin saturation (SaO2). Five different transducer/transducer attachment site (TIAS) combinations were evaluated; 1–3) a fingertip transmission transducer attached to the foal's ear, lip and tongue, 4) an adhesive transmission transducer positioned on the foal's ear and 5) a forehead reflectance transducer placed on the ventral aspect of the foal's tail-base. Eight normal, Quarter Horse foals (age 5–10 days) were studied while under general anaesthesia. Alterations in arterial carbon dioxide tension (PaCO2) were produced by changing the level of ventilation. At each level of ventilation, alterations of arterial haemoglobin saturation (SaO2) were produced by varying the inspired fraction of oxygen (FIO2). At each level of ventilation and each level of FIO2, arterial blood samples were obtained for blood gas analysis while pulse oximeter readings were recorded simultaneously for each TTAS combination. Arterial blood oxygen saturation (SaO2) was calculated from arterial blood gas values and the equine blood oxygen dissociation curve. Pulse oximeter readings from each TTAS combination were compared with SaO2 values with linear regression analyses. Bias and precision values were determined and the sensitivity and specificity of each TTAS combination for detecting desaturation (SaO2

An intrathoracic esophageal pulsion diverticulum causing repeated episodes of esophageal obstruction in a Morgan weanling colt was diagnosed by endoscopy, positive contrast radiography, and pleuroscopy. Surgical excision of the diverticulum alleviated clinical signs, and the horse was able to resume a normal diet by day 6. After 9 months the colt remains asymptomatic.