The effect of postsurgical pain on attentional processing in horses.

OBJECTIVE: To investigate the effect of postsurgical pain on the performance of horses in a novel object and auditory startle task. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty horses undergoing different types of surgery and 16 control horses that did not undergo surgery. METHODS: The interaction of 36 horses with novel objects and a response to an auditory stimulus were measured at two time points; the day before surgery (T1) and the day after surgery (T2) for surgical horses (G1), and at a similar time interval for control horses (G2). Pain and sedation were measured using simple descriptive scales at the time the tests were carried out. Total time or score attributed to each of the behavioural categories was compared between groups (G1 and G2) for each test and between tests (T1 and T2) for each group. RESULTS: The median (range) time spent interacting with novel objects was reduced in G1 from 58 (6-367) seconds in T1 to 12 (0-495) seconds in T2 (p=0.0005). In G2 the change in interaction time between T1 and T2 was not statistically significant. Median (range) total auditory score was 7 (3-12) and 10 (1-12) in G1 and G2, respectively, at T1, decreasing to 6 (0-10) in G1 after surgery and 9.5 (1-12) in G2 (p=0.0003 and p=0.94, respectively). There was a difference in total auditory score between G1 and G2 at T2 (p=0.0169), with the score being lower in G1 than G2. CONCLUSIONS AND CLINICAL RELEVANCE: Postsurgical pain negatively impacts attention towards novel objects and causes a decreased responsiveness to an auditory startle test. In horses, tasks demanding attention may be useful as a biomarker of pain.

Unilateral and bilateral laparoscopic ovariectomy of mares by electrocautery.

Twelve horses underwent standing laparoscopic ovariectomy using electrocoagulation and fine dissection as the only means of achieving haemostasis of the severed ovarian pedicle. Four mares had bilateral ovariectomy performed as a treatment for aggressive behaviour thought to be associated with the oestrous cycle. Eight mares had unilateral ovariectomy performed for removal of a granulosa thecal cell tumour (GCT). Electrocoagulation provided an effective means of haemostasis in both normal and pathological ovaries. Only one case (removal of a GCT) had mild haemorrhage following electrocoagulation, necessitating the need for the application of endoscopic clips to achieve haemostasis. Six of the horses developed minor wound complications (none of them requiring any additional treatment). Long-term follow-up information showed complete resolution of abnormal behaviour in all eight horses with GCTs, but in one of the four horses with normal ovaries the aggressive behaviour had not been completely resolved.

Study of crib-biting and gastric inflammation and ulceration in young horses.

Nineteen young horses that had recently started to perform the stereotypy of crib-biting were compared with 16 non-stereotypic horses for 14 weeks. After initial observations of their behaviour and an endoscopic examination of the condition of their stomachs, the horses were randomly allocated to a control or an antacid diet At the start of the trial, the stomachs of the crib-biting foals were significantly more ulcerated and inflamed than the stomachs of the normal foals. In addition, the faecal pH of the crib-biting foals (6.05) was significantly lower than that of the normal foals (6.58). The antacid diet resulted in a significant improvement in the condition of the horses' stomachs. The crib-biting behaviour declined in most of the foals, regardless of their diet, but tended to decline to a greater extent in the foals on the antacid diet.

Squamous cell carcinoma of the urethral process in a horse with hemospermia and self-mutilation behavior.

A 14-year-old Arabian stallion was examined because of acute hemospermia. The stallion was used in an artificial breeding program and had a 6-year history of low-grade hemospermia and a 4-year history of self-mutilation behavior. During previous examinations, minor irritation of the urethral process was identified as the source of the bleeding. Physical examination revealed a mucosal ulceration in the distal portion of the urethra. Histologic examination of a biopsy specimen from this area revealed low-grade squamous cell carcinoma. The urethral process was excised, and the hemospermia resolved. Frequency of self-mutilation behaviors also decreased after surgery, suggesting that there may have been a link between irritation of the urethral process and development of self-mutilation behavior.

Prevention of crib-biting: a review.

Crib-biting is a common oral stereotype. Because of perceived deleterious effects on the health and appearance of subjects the prevention of crib-biting is regularly attempted. The resourcefulness of horses in satisfying their motivation to perform this behaviour often frustrates owners' efforts at prevention. This paper reviews the efficacy and observable consequences of attempting to prevent crib-biting by a variety of methods. These include attempts to prevent the grasping of objects, to interfere with air-engulfing and to introduce punishment for grasping and neck-flexion. Other approaches include the use of surgery, acupuncture, pharmaceuticals, operant feeding and environmental enrichment. A remedy that is effective for every crib-biter remains elusive. We conclude that, rather than concentrating on remedial prevention, further research should be directed at establishing why horses crib-bite and how the emergence of crib-biting can be avoided.

Ovarian torsion associated with granulosa-theca cell tumor in a mare.

A 12-year-old Morgan mare was examined because of stallion-like behavior of 45 days' duration. Palpation per rectum and transrectal ultrasonographic examination revealed a large left ovary with multiple cystic areas and crepitus. A granulosa-theca cell tumor was suspected. During hospitalization for further evaluation of the affected ovary, the mare developed signs of abdominal pain. Exploratory surgery revealed a large left ovary, which was black with a necrotic and friable surface, and a 720 degrees clock-wise torsion of the ovarian pedicle. Torsion was corrected, and oophorectomy was performed. The mare recovered satisfactorily from surgery. Histologic diagnosis was granulosatheca cell tumor with marked diffuse necrosis. To our knowledge, torsion of the ovarian pedicle has not been reported in the veterinary literature. However, it is not uncommon in women. Ovarian torsion seems to develop in association with neoplasia, cysts, and ovarian hyperstimulation syndrome. Ovarian torsion should be considered as a differential diagnosis for mares with a known ovarian pathologic change such as neoplasia or abscess if signs of abdominal pain are evident.

The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies.

Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minutes before detomidine administration which was immediately before the administration of tolazoline or saline (time [T] = 0), and at 5, 30, and 60 minutes after injections of tolazoline or saline (T = 5, 30, and 60 minutes, respectively). Compared with heart rate at T = 0, tolazoline antagonism increased heart rate 45% at 5 minutes. There was no difference in heart rate between treatments at 30 minutes. Blood pressure remained stable after tolazoline, while it decreased over time after saline. Compared with concentrations at T = 0, tolazoline antagonism of detomidine in awake ponies resulted in a 55% increase in cortisol at 30 minutes and a 52% increase in glucose at 5 minutes. The change in free fatty acids was different for tolazoline and saline over time. Free fatty acids decreased after detomidine administration. Free fatty acids did not change after saline administration. After tolazoline administration, free fatty acids increased transiently. Tolazoline tended to decrease sedation and analgesia at 15 and 60 minutes postantagonism. Antagonism of detomidine-induced physiological and behavioral effects with tolazoline in awake ponies that were not experiencing pain appears to precipitate a stress response as measured by cortisol, glucose, and free fatty acids. If antagonism of an alpha-agonist is contemplated, the potential effect on hormones and metabolites should be considered.