Earl M. Gaughan

Cryptorchidism in North American cattle: Breed predisposition and clinical findings

The authors analyzed data collected over 26 years from 143 cryptorchid bulls admitted to 23 North American veterinary schools. Breed was found to be a risk factor. The medical records of 41 cryptorchid cattle were also obtained, and the physical examination findings, method of diagnosis, and surgical management were recorded. Polled Hereford and Shorthorn cattle were at significantly greater risk for cryptorchidism; however, polled cattle were not at an increased risk for cryptorchidism. Cryptorchidism was most commonly diagnosed by external palpation of the superficial inguinal rings and by palpation per rectum. Unilateral cryptorchidism appears to be more common than bilateral cryptorchidism. The incidence of cryptorchidism was 69% for the left testis and 31% for the right testis. Sixty-six percent of the retained testes were located in the inguinal canal. Cryptorchidectomy was performed through an inguinal, paramedian or flank approach in 26 bulls. Cryptorchidism appears to be rare in bovine bulls admitted to North American veterinary schools, with 1.7 cases per 1,000 bull admissions. We suggest that cryptorchidism be considered an inherited trait in the Shorthorn and Polled Hereford breeds.

Arthroscopy in Food Animal Practice

Arthroscopy can be an effective technique for diagnosis and treatment of various orthopedic disorders in cattle, including septic arthritis and osteochondrosis. Cost of equipment and surgery may be prohibitive for some individuals, yet the techniques of arthroscopic surgery are proven efficacious when applied to cattle. Arthroscopic techniques may also be quite useful in the evaluation and treatment of the same disorders in sheep, goats, and camillids. The technology remains the same and applicability rests with financial constraints and the physical aspects of specific species and joints. We speculate that arthroscopy would be quite useful for exploration and treatment of the larger joints and other selected joints of these species.

Exercise Intolerance in Endurance Horses

Endurance competition requires synchronism and development of metabolic and musculoskeletal systems. An understanding of the existence of performance-limiting factors may permit the detection of exercise intolerance that could lead to performance failure, fatigue, and exhaustion. New concepts for assessment of fitness have increased the understanding of individual capacities and deficiencies and the interaction of the different systems involved in exercise.

The effect of intra‐articular methylprednisolone acetate and exercise on equine carpal subchondral and cancellous bone microhardness

Dorsal carpal osteochondral injury is a major cause of lameness in horses undergoing high intensity training. Intra-articular corticosteroid treatment is used commonly to manage exercise-associated articular pain, but its use remains highly controversial in the equine athlete. This project, therefore, aimed to compare the mechanical properties of intra-articular MPA and diluent-treated middle carpal subchondral and cancellous bone in horses undergoing a short-term treadmill exercise programme. It was hypothesised that subchondral and cancellous bone mechanical properties are influenced by intra-articular administration of methylprednisolone acetate (MPA). Eight 2-year-old female horses had MPA or diluent administered into contralateral middle carpal joints at 14 day intervals, for a total of 4 treatments per horse. Horses underwent a standard treadmill exercise protocol until euthanasia (Day 70). Standard sites were located on the dorsal aspect of third, radial and intermediate carpal bones. Osteochondral samples from each test site were divided into subchondral bone and cancellous bone portions. These were dried, resin-embedded and gold-coated. Microhardness measurements were obtained at each test site. No significant effect of intra-articular treatment was detected. At each site, cancellous bone trabecular struts had an 18-19% higher microhardness value than the overlying subchondral bone. These findings indicate that intra-articular administration of MPA at this dose has no effect on subchondral or cancellous bone adaptation to short-term exercise and, therefore, on the propensity of carpal bones to injury. Further investigation into the calcified cartilage layer, effect of different corticosteroid preparations and diffusion of medication are required.

Dental Surgery in Horses

Dental surgery is most often directed at removal of diseased or injured teeth by the least invasive method possible. Some procedures available can preserve traumatized or infected teeth. Complications of dental surgery are well documented and often encountered by veterinary surgeons. Principles of debridement, curettage, lavage and ventral drainage combined with appropriate medicinal management can reduce complications and lead to successful outcome after dental surgery.

Skeletal Origins of Exercise Intolerance in Horses

Skeletal origins of exercise intolerance and performance failure can reside in multiple tissues. Diagnosis of injury that results in an ability to continue to exercise, yet inefficiently do so, requires familiarity with evaluation of subtle lameness and often with the specific demands of the different equine sports. Imaging is usually vital to diagnosis development and understanding of lesion influences on locomotion. Therapy is lesion dependent. Return to competitive exercise and performance is dictated by an understanding of skeletal tissue response to injury, rational progressive treatment, and a controlled reintroduction of exercise demands.

Diagnostic Approach to Exercise Intolerance in Racehorses

The diagnostic approach to the exercise intolerant racehorse depends on sound, fundamental steps to allow complete examination of the entire horse in a logical, time-efficient fashion. Availability of referral diagnostic modalities should not overshadow the need for collecting a clinical history or performing a complete physical examination. The diagnostic approach to exercise intolerance can be divided into a few basic steps. The first step, conducted without the horse, is a thorough discussion about the horse with the trainer and/or owner. Many clinical histories are complex and therefore following a predetermined pattern is helpful. Racing ability, general health history, historic problems with the major body systems including the musculoskeletal, respiratory, cardiovascular, and neurologic systems should be reviewed. The next step of the examination is conducted in the stall. A complete physical examination is required. The practitioner should pay close attention to the body systems that most frequently harbor causes of exercise intolerance. Before evaluating the horse for lameness, endoscopy of the upper airway should be performed. The final step is conducted outside the stall: completion of the lameness and neurologic examination or an exercise trial followed by further diagnostic tests such as a serum chemistry profile, bronchoalveolar lavage, or imaging studies. Decision for referral is best made after the physical examination is completed and capability for further diagnostics is exhausted.