Low heels are the most common hoof conformational abnormality seen in both the front and hind feet of horses. A low/negative distal phalanx angle in the front feet has been associated with palmar heel injuries but only recently has the significance of low/negative angles in the hind feet received attention. A study including a greater number of horses more representative of the UK horse population would be useful to UK equine practitioners. Our null hypothesis was that the plantar distal phalanx angle does not differ between horses with and without hindlimb lameness. For this prospective case-controlled study, horses presenting for orthopaedic complaints underwent a complete lameness assessment. The plantar distal phalanx angulation (PDPA), the angle between a line parallel to solar surface contacting the ground and the solar margin of the distal phalanx, was calculated from lateromedial radiographs. Horses were included in the study if hindlimb lameness was definitively localised by diagnostic anaesthesia. Student's t-tests and multivariable linear regression models were used for statistical analysis. One hundred and eighty-two horses met the inclusion criteria, 132 with hindlimb lameness and 50 controls. The mean left PDPA for HLL group was À1.0°vs. +1.8°for the controls. The mean right PDPA for HLL group was À1.1°vs. +1.4°in controls (both P<0.001). Lameness was most frequently localised to the stifle (59% of horses), followed by the distal tarsal joints and the proximal suspensory region. A limitation of the study was that the control group included some forelimb lame horses. It was concluded that horses with hindlimb lameness, including lameness localised to the stifle, were more likely to have negative PDPAs. While Pezzanite et al. (2019) previously reported a relationship between negative/neutral PDPA and tarsal/metatarsal lameness, this study is the first to find a relationship to stifle lameness, which may reflect differences in the populations of horses examined. Further kinematic studies are required to determine whether it is a cause or effect relationship.

SummaryMonorchidism describes the complete absence of one testis and is rare in horses. This study reports the clinical findings in 10 horses diagnosed as monorchids by standing laparoscopy or exploratory laparotomy. Hospital records for all horses undergoing cryptorchidectomy (2000–2016) in four centres were reviewed from which horses diagnosed with monorchidism were identified. Surgery was by either standing flank laparoscopy or an inguinal exploration and subsequent exploratory laparotomy under general anaesthesia. Ten horses were diagnosed as monorchids, five by laparoscopy (one bilateral laparoscopy) and five by laparotomy. Nine horses had a normally descended scrotal testicle, which was also removed at surgery. The right testicle was absent in three horses, and the left testicle was absent in seven horses. Anatomical findings were recorded in each case; the vaginal process was present in all horses, ductus deferens and epididymis were present in 80% of horses and the ligament of the tail of the epididymis and testicular vessels were present in 50% of horses. Laparoscopy allowed easy identification of spermatic structures enabling a prompt diagnosis of monorchidism. In conclusion, when monorchidism occurs, most other associated spermatic structures are likely to be present. A diagnosis of true monorchidism is reliant on hormonal testing and absence of testicular tissue on histopathology and so some of these horses may strictly be somewhere on the spectrum of testicular degeneration. This information is particularly useful in the surgical situation when it is not clear whether the testicle is present or not.

Low heels and negative plantar angles in the hind feet are the most common hind foot conformational abnormality. A causal relationship has been demonstrated between these conditions and hindlimb lameness. It is important these abnormalities are recognised during thorough orthopaedic examinations, so they can be quantified with radiography and appropriately treated with therapeutic farriery to restore optimal hoof conformation, balance and function. This is an essential part of a holistic approach to treating horses with hindlimb lameness. Farriery intervention for these abnormalities involves returning the plantar half of the foot to a load-sharing plane between the frog and heels, restoring phalangeal alignment and providing increased ground surface plantar to the centre of rotation of the distal interphalangeal joint.

A five-month-old Connemara foal presented for acute-onset, severe left forelimb lameness with fever, neutrophilia and an elevated serum amyloid A concentration. Radiographs were suspicious of septic physitis of the proximal humerus. CT identified a large defect involving the central portion of the subchondral bone plate of the glenoid and a sequestered bony fragment within the defect, which were not seen radiographically. CT findings were consistent with septic epiphysitis and sequestrum formation, which had significant implications on available treatment options. The foal was given a poor prognosis for returning to soundness so was subject to humane euthanasia.