Francis Verschooten

Estimates of regional cerebral blood flow and 5-HT2A receptor density in impulsive, aggressive dogs with 99mTc-ECD and 123I-5-I-R91150

Impulsive aggression in dogs has an important impact on human public health. Better insight into the pathophysiology of this phenomenon could lead to more adequate diagnosis and treatment. Indirect in vivo research on peripheral body fluids and post-mortem studies in impulsive animals and humans indicate a deficient serotonergic system in general and disturbances in the serotonin-2A (5-HT2A) receptor in particular. In this study, brain perfusion and the 5-HT2A receptors were examined in impulsive, aggressive dogs, in comparison with a group of normally behaving animals. In order to decide which dogs to include in this study, owners were asked to describe the general behaviour of the dogs, the circumstances in which aggression occurred and their conduct during aggressive acts. Finally, 19 dogs were retained for this study, showing, according to different behavioural specialists, disinhibited dominance aggression. Functional imaging studies were performed on all these dogs. Single-photon emission tomography (SPET) was used to measure regional brain perfusion using technetium-99m labelled ethyl cysteinate dimer (ECD). The 5-HT2A receptor binding properties were investigated using the selective radioligand iodine-123 labelled 5-I-R91150. A significant increase in uptake of the 5-HT2A radioligand was noted in all cortical areas. No significant alterations were found in regional cortical perfusion, indicating that the increased binding index was not a consequence of increased tracer delivery. This study supports a role for the serotonergic system in canine impulsive aggression.

Navicular disease in the horse: the effect of controlled intrabursal corticoid injection.

Summary In horses with clinical signs of navicular disease without radiographic signs (CND) and horses with clinical and radiographic signs of navicular disease (C/RND) injection of corticoids into the bursa podotrochlearis was controlled by indirect and instant fluroscopy. The horses were rested for about three days after the injection and were allowed almost full work immediately thereafter. Injections were made in 161 horses during a ten-year period and longterm evaluation was possible in 148 horses by means of mostly a questionnaire or by re-examination. In 19.5% of these horses the injection had no effect at all and in 80.4% of the horses an immediate result was obtained: the effect of the injection lasted less than one month in 14.1%, one month in 6% and two months and more in 60%. The injection is not a cure for navicular disease, but may render a horse quickly serviceably sound for quite a long period. In the meantime it is a diagnostic test to localize pain in ND. If corrective shoeing and or medication with isoxsuprine is ineffective, intrabursal treatment should be tried before neurectomy. In unilateral ND, a clinically silent ND on the other leg may be activated when only the affected side is treated intrabursally and the horse worked thereafter. Abuse of intrabursal corticoid injection is possible in the horse business and the veterinarian shouldbe responsible in the application of the technique.

The use of magnetic motor evoked potentials in horses with cervical spinal cord disease

The aim of this study was to investigate the use of magnetic motor evoked potentials as an ancillary diagnostic test in horses with cervical cord lesions. Transcranial magnetic stimulation was performed in 12 ataxic horses and the results of the evoked responses were compared to those found in normal horses. The latency and peak-to-peak amplitude of the potentials in the 12 ataxic horses were significantly different from those measured in normal horses. The configuration of the abnormal potentials was also polyphasic. Normalisation of the evoked potentials occurred in none of the horses, presented after a period of clinical improvement. These findings demonstrate that the technique is also able to detect lesions in horses with subtle clinical signs of incoordination. Magnetic transcranial stimulation is a valuable ancillary test to assess the integrity of the motor tracts. The technique is painless and safe and shows good sensitivity to detect lesions along the descending motor pathways.

Biodistribution and displacement studies of the selective 5-HT2Areceptor antagonist 123I-5-I-R91150 in the normal dog

There is increasing interest in mapping receptors in vivo by using functional imaging modalities such as single photon emission tomography (SPET) and positron emission tomography (PET). Since SPET is a more accessible functional imaging modality than PET and, overall, it is more economical, radioligands suitable for this technique are in greater demand. Recently, 123I-5-I-R91150, a radioligand with high selectivity and affinity for 5-HT2A receptors in the brain, was introduced for SPET. This study reports on the whole-body distribution and brain uptake of the selective 123I-5-I-R91150 ligand in four normal dogs. The frontal to cerebellar ratio of uptake in time was determined in three dogs. Time-activity curve of venous blood was determined in one dog. Maximal global brain uptake was found at 10-60 min post-injection. Higher brain uptake was noted in the frontal cortical areas compared to the cerebellum. The frontal-cerebellar ratio reached the highest values at 90-180 min. Reversibility and pharmacological selectivity of ligand binding was demonstrated through displacement and blocking studies with the 5-HT2A receptor antagonist ketanserin. This study demonstrates that the specific 5-HT2A iodinated ligand can be used for imaging and semi-quantification of the 5-HT2A receptors in the canine brain in vivo by using SPET.

Conservative and surgical treatment of tibial fractures in cattle

Ninety-five cattle with tibial fractures, all but one with a uni-lateral fracture, were examined between 1990 and 1994. The feasibility of repairing the fracture was assessed radiographi-caily, also taking into account the bodyweight and value of the animal. Twenty-two cattle were slaughtered. Conservative treatment with stall confinement and/or a splint or cast was applied in 18 cases, with satisfactory results in eight of them (44 per cent). They were fattened to normal bodyweight, but they all had a severe deformity of the affected leg. In 55 ani-mals, the fractures were fixed externally with Steinmann pins and methylmethacrylate bridges under image-intensi-fied fluoroscopy. Ten of them could not bear weight on the affected leg and were slaughtered before the pins were removed. In the remaining 45 animals the pins were removed after a mean (sd) period of 71 (14) days. Four ani-mals re-fractured the affected leg shortly after the pins were removed and six others were slaughtered prematurely because of inadequate weight bearing. The results were suc-cessful in 35 cases (64 per cent). Slight deviations of the affected leg and/or the contralateral leg were often observed. The overall survival rate of the cattle with tibial fractures was 45 per cent.

A review of the human and veterinary literature on local anaesthetics and their intra-articular use. Relevant information for lameness diagnosis in the dog.

Lameness in dogs is often a diagnostic challenge. In many cases it is difficult to determine the exact localisation of lameness because of the absence of palpable changes, or because of unreliable pain response due to high pain tolerance, stress or aggression of the dog. In horses and humans, intra-articular administration of local anaesthetics is commonly used for diagnostic purposes. In this review, information from human and veterinary studies on different local anaesthetic agents and their application for diagnostic intra-articular anaesthesia is given. Based on this information, a protocol for diagnostic intra-articular anaesthesia in the dog can be developed and evaluated in future studies.

Results of conservative treatment of osteochondrosis of the tibiotarsal joint in the horse

Summary The present study relates to 146 horses (Warmbloods and Standardbreds) exhibiting tibiotarsal joint distension and radiographic signs of OCD. Conservative treatment included normal box rest or a less intense training program together with a low energy diet. Follow-up time ranged from 6 months to 5 years and was acquired from a question-naire addressed to the owners. Localization of the lesion in the joint did not seem to play an important part in the clinical symptoms. A final evaluation was achieved in 96 horses. Sixty percent of the Warmbloods and 18% of the Standardbreds performed normally. Eighteen percent of the Standardbreds performed beyond level as opposed to 10% of the Warmbloods. Forty-one percent of the Standardbreds and 7% of the Warmbloods (66% with additional femoral ridge involvement) performed badly. Finally, 23% of the Standardbreds and 23% of the Warmbloods could not perform because problems (not related to the OCD of the tibiotarsal joint) developed during the follow-up period. If the performance problems which were not related to OCD of the tibiotarsal joint were excluded, good results were obtained in 80% of the Warmbloods, compared to only 23% of the Standardbreds. Therefore, systemic arthroscopic treatment of tarsal OCD is questionable in Warmbloods, in contrast with Standardbreds.

Diagnostic intra-articular anaesthesia of the elbow in dogs with medial coronoid disease

OBJECTIVE Assessment of the effect of intra-articular anaesthesia on lameness caused by medial coronoid disease. METHODS This study included 90 dogs that were evaluated for the complaint of unilateral forelimb lameness. All dogs were suspected of having an elbow problem for which orthopaedic examination and radiographs showed inconclusive findings. Following a short sedation, mepivacaine was injected intra-articularly to determine whether lameness was caused by a suspected elbow problem. This effect was compared with the final diagnosis based on computed tomography and arthroscopy. RESULTS Out of 90 dogs, 78 (87%) dogs had an improvement of lameness after injection of the local anaesthetic, which confirmed the elbow joint as the primary source of lameness. A positive response was seen in all types of medial coronoid lesions. A false negative result was observed in 12 dogs (13%). CLINICAL RELEVANCE Medial coronoid disease is represented by different types of pathologic lesions including chondromalacia, fissures, fragments, and medial compartment disease. Diagnosis may be difficult because of limited clinical or radiographic signs or a combination of both. Intra-articular anaesthesia can be a helpful diagnostic tool to localize the problem by eliminating pain and reducing lameness to a great extent in all types of coronoid lesions.

Evaluation of two sedation protocols for use before diagnostic intra-articular anaesthesia in lame dogs

OBJECTIVES To assess the influence of two sedation protocols on the degree of lameness in dogs. METHODS Fifty lame dogs were allocated to one of two sedation protocols. Group ACPM (acepromazine + methadone; n=25) was sedated with acepromazine and methadone. Group MED (medetomidine antagonised with atipamezole; n=25) was sedated with medetomidine and reversed with atipamezole. Each dog was evaluated for lameness before and after sedation using videotapes. Four experienced clinicians allocated global lameness scores before and after sedation to each dog using a numerical rating scale. RESULTS In 80% of the dogs in group ACPM and in 72% in group MED lameness was not affected by the sedation. In 12% of the dogs in group ACPM and 20% of the dogs in group MED the observers noticed an increase of lameness of 1 or 2 degrees on a scale of 0 to 10. In 8% of the dogs in both groups lameness decreased with 1 degree. CLINICAL RELEVANCE A possible diagnostic test for investigation of obscure lameness is intra-articular anaesthesia. Sedation is necessary to allow intra-articular injection. This study provided evidence that the effect of sedation with the proposed protocols on the degree of lameness is negligible.

Soft tissue metastasis of an osteosarcoma of the humerus in a four-legged patient.

1. Forrest LJ, Thrall DE. Bone scintigraphy for metastasis detection in canine osteosarcoma. Vet Radiol Ultrasound 1994; 35:124–130. 2. Daniel GB, Avenell JS, Young K, Mason GL, Hahn KA. Scintigraphic detection of subcutaneous metastasis in a dog with appendicular osteosarcoma. Vet Radiol Ultrasound 1996; 37: 146–149. Kathelijne Peremans (✉) Department of Medical Imaging, Faculty of Veterinary Medicine, University of Ghent, Salisburylaan, 133, 9820 Merelbeke, Belgium e-mail: kathelijne.peremans@rug.ac.be Image of the month