Hypervitaminosis A in the cat: a case report and review of the literature

A case of hypervitaminosis A with secondary entrapment and compression of the left brachial plexus nerve roots is described. A 9-year-old male castrated domestic shorthair, fed a home-made diet based on raw pork liver, was submitted for examination for a left forelimb lameness that evolved to paralysis over a 2-month period. Clinical examination revealed a flaccid paralysis and atrophy of all left forelimb muscles. An ipsilateral Horner's syndrome was also noted. Radiological examination of the cervical and thoracic spine showed massive new bone formation at the ventral aspect of the second cervical to sixth thoracic vertebra. The diagnosis of hypervitaminosis A was made, based on the clinical and radiographic findings, as well as the determination of serum vitamin A concentration, which was 630 microg/dl, three times above the upper normal limit for this species. Despite the unfavourable initial prognosis, the cat progressively regained function of the affected limb approximately 6 months after the diet was changed to a commercial canned food.     

Bilateral, hypertrophic neuritis of the brachial plexus in a cat: magnetic resonance imaging and pathological findings

A 9-year-old Burmese cat was presented for investigation of a subacute onset of bilateral forelimb paresis. Magnetic resonance imaging of the cervico-thoracic vertebral column and brachial plexus revealed a bilaterally symmetrical, severe and diffuse swelling of the spinal nerves forming the caudal part of the brachial plexus. Histopathology of the abnormal nerve roots, spinal nerves and brachial plexi showed inflammatory and marked proliferative changes with similar features to that of hypertrophic neuritis of man. Hypertrophic neuritis in man is a rare, tumor-like, chronic inflammatory peripheral nerve disorder of unknown origin most frequently involving the brachial plexus.     

MAGNETIC RESONANCE IMAGING AND ULTRASONOGRAPHY IN THE DIAGNOSIS OF A MALIGNANT PERIPHERAL NERVE SHEATH TUMOR IN A DOG

A 9-year-old male neutered mixed breed dog had a two-month history of progressive left thoracic limb lameness. There was electromyographic evidence of denervation potentials in all muscles of this limb. In magnetic resonance images a multilobulated, hyperintense mass was visible caudal to the middiaphysis of the left humerus on T-2 weighted images. The mass, which was isointense with surrounding tissue on T1 weighted images, extended proximally towards the brachial plexus. The mass was also visible as a fusiform structure of mixed echogenicity sonographically, although fine-needle aspiration performed at this time was nondiagnostic. A malignant peripheral nerve sheath tumor was diagnosed histopathologically.     

Concurrent Fusarium chlamydosporum and Microsphaeropsis arundinis infections in a cat

A 7-year-old cat was presented initially with multiple draining sinuses on the metatarsal region of its right hindlimb. Another lesion had appeared at the same time on the fifth proximal interphalangeal joint of the left forelimb. Histopathological examination of a biopsy from the right hindlimb lesion revealed chronic pyogranulomatous inflammation associated with yeast-like bodies and septate mycelia; a fungus was cultured on conventional media but not identified further. Culture of a swab collected from the left forelimb lesion demonstrated a pigmented fungus, also not characterised further. Although there was initially a favourable response to ketoconazole (Nizoral, Janssen-Cilag Pty. Ltd) and beta-lactam therapy, the infection in the hind limb relapsed subsequently, and Fusarium chlamydosporum was cultured from deep biopsy specimens. Clinical improvement followed debridement and itraconazole (Sporanox, Janssen-Cilag Pty. Ltd; 100 mg orally once daily), however amputation of the limb represented the best chance for a cure. The cat made an uncomplicated recovery following surgery and remained well for five months until the lesion on the left forelimb recurred. Amputation of the distal fourth digit was then performed, and the resected tissue submitted for culture. The dematiaceous fungus Microsphaeropsis arundinis was subsequently cultured. The cat remained well for several months, until a further F. chlamydosporum infection developed on the body wall. This was excised 7 months ago, and no lesions have recurred in this area. Importantly, this is the first reported case of M. arundinis infection in a mammalian host.     

Nerve sheath tumours in the dog and cat

Schwannomas were diagnosed in twelve dogs and five cats at Massey University Small Animal Clinic and Hospital over a 15-year period (1977-92). A further two feline cases were reported at the Batchelar Animal Health Laboratory. In six dogs, the tumour involved nerves of the brachial plexus. Clinical signs observed in these dogs were forelimb lameness, muscle wasting and pain on movement of the affected limb or neck. Hindlimb paresis was observed in two dogs. Surgical excision of the brachial plexus tumour was attempted in one dog, leading to an 8-month remission of signs. In one dog, the tumour involved the sacral nerves, and in two dogs the cranial nerves were affected. Three dogs had skin nodules. Seven of the twelve affected dogs were destroyed. In five cats, the tumours developed on the carpus, tarsus or interdigital area of a forelimb or hindlimb as a slowly developing nodular lesion. In the other two cats, the site of the tumour was the flank and the lateral thigh respectively. Surgical excision of the tumour was successful in three cats.     

A novel technique of ultrasound-guided brachial plexus block in calves

An interventional ultrasound technique to increase the safety of surgical treatment of the calf forelimb was tested. First, the brachial plexus was evaluated using ultrasonography and then 2% lidocaine was injected under ultrasound guidance. Ultrasonically, the brachial plexus appeared as multiple hypoechoic areas surrounded by a hyperechoic rim or a hyperechoic structure characterised by multiple discontinuous lines. It was located between the omotransverse muscle and axillary artery and vein. The sensitive effect in the forelimb was seen mainly in the area supplied by the musculocutaneous nerve, indicating successful blockage in the nerve plexus. Out of the eight forelimbs, the motor effect was observed in seven forelimbs. These results suggest the clinical feasibility of ultrasound-guided brachial plexus block in bovine medicine, although further studies are needed to examine various approaches, including the sites of needle insertion and the appropriate volume and dosage of anaesthetic.     

Postanesthetic Neuropathy/Myopathy in the Nondependent Forelimb in 4 Horses

Postanesthetic lameness in the form of myopathy or neuropathy is a well-known complication associated with equine general anesthesia and is most often reported in the dependent limb of horses treated in lateral recumbency. The aim of this case series was to report clinical data of 4 horses treated under general anesthesia in lateral recumbency and that developed postanesthetic neuropathy/myopathy in the nondependent forelimb. With anti-inflammatory and analgesic medical treatment, locomotor problems associated with neuropathy/myopathy resolved after 12–24 hours in all cases. The pathogenesis remains unclear. A first hypothesis may be the decreased hydrostatic pressure in limb vessels elevated above the level of the heart, and consequent reduction of muscle perfusion. Second, abduction and/or endorotation of the upper forelimb may have caused injury to the brachial plexus. Therefore, positioning of the nondependent forelimb should be done judiciously and may be the subject of further research.     

Appendicular arterial tumor embolization in two cats with pulmonary carcinoma

A 13-year-old neutered male Persian cat and an 11-year-old neutered female Persian cat were examined because of an acute onset of lameness. In both cats, conscious proprioception and reflexes were diminished in the affected limb. In 1 cat, no blood flow was detected in the left brachial artery with a Doppler ultrasonic flow detector, whereas blood flow in the right brachial artery was easily documented. In the other cat, the right femoral pulse was not palpable. Neither cat had any echocardiographic evidence of cardiac disease. In both cats, treatment was primarily supportive. One cat died, and the other was euthanatized. At necropsy, lung lobe consolidation was seen. Microscopically, there was multifocal infiltration of the lung parenchyma with cuboidal to columnar neoplastic epithelial cells. Neoplastic epithelial cells of similar morphology were identified in nodular masses in sections of muscle, and intravascular tumor emboli were identified obliterating small and large arterioles. Immunohistochemical staining of pulmonary and muscular tissue for pan-cytokeratin antigen revealed intense cytoplasmic staining of neoplastic cells. Staining for factor VIII-related antigen confirmed that clusters of neoplastic cells represented intravascular emboli. Clinical signs in the cats were attributed to arterial occlusion by tumor emboli.     

Gait analysis in a cat with scapular luxation and contralateral forelimb amputation

This report describes the use of a pressure-sensitive walkway to evaluate an uncommon case of a cat with dorsal luxation of the left scapula and an amputated right forelimb. The findings suggest that limb amputation induced load redistribution mostly to the contralateral forelimb despite the scapular luxation.     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF PERIPHERAL NERVE SHEATH TUMORS OF THE CANINE BRACHIAL PLEXUS IN 18 DOGS

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.     

Sub‐acute and chronic MRI findings in bilateral canine fibrotic contracture of the infraspinatus muscle

A six‐year‐old, 30‐kg female German pointer dog was presented for examination with a history of pre‐existing right‐forelimb lameness and more recent (3 months) persistent lameness in the left‐forelimb. Physical examination revealed mild left‐forelimb lameness and a mild circumduction movement. There were no signs of pain or crepitation detected during manipulation of the shoulders, but the animal was unable to fully flex both glenohumeral joints. Magnetic resonance imaging, using fast recovery fast spin echo T2‐weighted and fat saturated proton density sequences, revealed abnormal heterogeneous hypointensity in the right infraspinatus muscle and a heterogeneous hyperintense area in the left infraspinatus muscle. Surgical treatment consisting of a bilateral infraspinatus tenectomy resulted in improved limb function. Histopathological examination demonstrated tissue changes in the right infraspinatus, characterised by myofibre degeneration and fibrosis, compatible with a chronic degenerative process, while changes in the left infraspinatus muscle were characterised by variable degrees of fibre degeneration, haemorrhage and interstitial oedema.     

Osteolysis of the radius and ulna induced by a circumferential foreign body in a cat

CASE DESCRIPTION: A 1-year-old neutered male cat was examined because of a 6-month history of recurrent swelling and draining wounds affecting the craniomedial aspect of the distal portion of the left forelimb. CLINICAL FINDINGS: No lameness or neurologic deficits were evident. Examination of craniocaudal and lateromedial radiographic views revealed nonprogressive circumferential osteolysis and a mildly radiopaque, ring-shaped foreign body surrounding the radius and ulna. TREATMENT AND OUTCOME: During surgery, a tight elastic band surrounded by a thick fibrous tissue capsule was found encircling the limb. Microbial culture yielded a Staphylococcus sp that was susceptible to clindamycin. Follow-up monitoring via telephone communication with the owners 1.5 years after removal of the foreign body indicated that the cat had healed with no recurrence of drainage. CLINICAL RELEVANCE: Pressure osteolysis of the bones of the forelimb can be caused by a circumferential foreign body without associated neurologic abnormalities or lameness.     

ULTRASONOGRAPHIC ANATOMY OF THE BRACHIAL PLEXUS AND MAJOR NERVES OF THE CANINE THORACIC LIMB

A technique for ultrasonography of the brachial plexus and major nerves of the canine thoracic limb is described based on examination of five canine cadavers and three healthy dogs. The ventral branches of the spinal nerves that contribute to the brachial plexus are identifiable at their exit from the intervertebral foramina. These nerves may be followed distally, cranial to the first rib, until they form the brachial plexus. The musculocutaneous, ulnar, and median nerves are identified on the medial aspect of mid‐humerus and followed proximally to the axillary region and distally to the elbow. The radial nerve, formed by multiple nerve components, is seen on the mediocaudal aspect of the humerus. Nerves appear as hypoechoic tubular structures with an internal echotexture of discontinuous hyperechoic bands, surrounded by a thin rim of highly echogenic tissue. Improved understanding of the ultrasonographic anatomy of the brachial plexus and its main branches supports clinical use of this modality.     

Dorso-medial ante-brachiocarpal luxation with radio-ulna luxation in a domestic shorthair

An 8-year-old domestic shorthair was admitted with non-weight bearing left forelimb lameness. Examination and radiographs revealed dorso-medial ante-brachiocarpal luxation with palmar luxation of the distal radio-ulnar joint. Primary repair was performed and stabilised using an arthrodesis wire and type Ia Kirschner-Ehmer (K-E) external skeletal fixator (ESF). The cat regained excellent pain-free limb function by 14 weeks with only minor reduction in range of movement. This is the first case report of a cat with distal radio-ulnar joint luxation associated with ante-brachiocarpal luxation. Primary repair of carpal luxation in the cat should be considered before arthrodesis.     

Cinematographic analysis of the gait of lame horses V: Fibrotic myopathy

A horse with fibrotic myopathy of the semitendinosus muscle of the right hind limb was studied. Observation of the horse in movement showed that protraction of the affected limb terminated abruptly and the hoof was slapped down on the ground. High speed cinematography with computer-aided analysis of the film was used to analyze the gait in greater detail. The results showed that the right hind limb approached the ground almost vertically making impact toe-first, whereas the left hind limb was moving forward relative to the ground when it made heel-first impact. Significant differences were recorded in the sequence and placement of the limbs on the 2 diagonals. The hind limb preceded the forelimb at impact on both diagonals, but at lift-off the lame right hind limb preceded the left forelimb, whereas the sound left hind limb lifted off later than the right forelimb. The distance between the diagonal limb pair during the stance phase was shorter for the left diagonal (left fore-right hind limb pair) than for the right diagonal (right fore-left hind limb pair) (P<0.01). The suspension following the left diagonal was longer than that following the right diagonal (P<0.01).     

MALIGNANT SCHWANNOMA OF THE BRACHIAL PLEXUS IN A DOG

A 4-year-old Labrador bitch was presented for veterinary examination with a history of lameness and muscle atrophy of the left forelimb. On clinical examination a painful mass was detected medial to the left shoulder joint. Radiographs of the shoulder showed mineralisation of this mass. Exploratory surgery revealed a tumour involving the radial nerve, axillary nerve and the trunk of the median and ulnar nerves. Histopathologic diagnosis was a malignant Schwannoma.     

Evaluation of short-term limb function following unilateral carbon dioxide laser or scalpel onychectomy in cats

OBJECTIVE: To evaluate short-term postoperative forelimb function after scalpel and laser onychectomy in cats. DESIGN: Randomized, prospective study. ANIMALS: 20 healthy adult cats. PROCEDURES: Cats were randomly assigned to the laser (n = 10) or scalpel (10) onychectomy group. Unilateral left forelimb onychectomy was performed. In the scalpel group, a tourniquet was used during surgery and a bandage was applied after surgery. Pressure platform gait analysis was performed prior to and 1, 2, 3, and 12 days after onychectomy. Peak vertical force (PVF), vertical impulse, and the ratio of the PVF of the left forelimb to the sum of the remaining limbs (PVF ratio) were used as outcome measures. RESULTS: The laser onychectomy group had significantly higher ground reaction forces on days 1 and 2 and significantly higher PVF ratio on day 12, compared with the scalpel group. Similarly, significant differences were found in change in ground reaction forces on days 1 and 2 and the PVF ratio on day 12, compared with day -1. No cats required rescue analgesia during the course of the study. One cat in the laser group had signs of depression and was reluctant to walk on day 2 after surgery, had physical examination findings consistent with cardiac insufficiency, and was euthanized. CONCLUSIONS AND CLINICAL RELEVANCE: Cats had improved limb function immediately after unilateral laser onychectomy, compared with onychectomy with a scalpel, tourniquet, and bandage. This improved limb function may result from decreased pain during the 48 hours following unilateral laser onychectomy.     

ULTRASONOGRAPHIC EVALUATION OF BRACHIAL PLEXUS TUMORS IN FIVE DOGS

Five dogs with unilateral thoracic limb lameness, neurologic deficits, muscle atrophy, and pain, or a combination of these signs, were examined using ultrasonograghy. Large, hypoechoic tubular masses that displaced vessels and destroyed the normal architecture were found in each dog. The affected axilla of each patient was then imaged with computed tomography or magnetic resonance to fully assess the extent of the masses. We describe the use of ultrasound in screening patients for brachial plexus tumors.     

Hematogenous metastasis of embryonal rhabdomyosarcoma originating from skeletal muscle in a young dog.

An 8-month-old, intact male Golden Retriever with a history of left forelimb lameness for 2 months was presented to the Veterinary Medical Teaching Hospital of Konkuk University (Seoul, Korea). Results of a physical examination revealed a mass in the left axillary region. A thoracic radiography showed an osteolytic lesion in the scapula and the presence of a soft tissue density from the thoracic wall to the scapula. A computerized tomography revealed a mass invading into the scapula, and small nodules in the lung that suggested metastasis. At necropsy, a pale-yellow, irregular, firm, 8 x 10 x 5 cm mass extended from axillary region and destroyed the scapular. In addition, small nodules were noted in the lung. On microscopic examination, the mass consisted of round-to-oval cells, with eccentrically located hyperchromatic nuclei and eosinophilic cytoplasm in fibromyxoid stroma. Tumor cells were observed in blood vessels in the primary mass. Tumor cells strongly expressed vimentin, desmin, and myoglobin. In phosphotungstic acid-hematoxylin staining, cross-striations were detected in rhabdomyoblasts. In periodic acid-Schiff reaction, only a few cells were detected. The diagnosis was primary rhabdomyosarcoma of the appendicular muscle of a young dog. The tumor presumably originated in the skeletal muscle of the limb, invaded into the adjacent scapular bone, and metastasized to the lung.     

AGE-RELATED CHANGES IN THE ULTRASOUND APPEARANCE OF THE NORMAL FELINE PANCREAS

In humans, pancreatic hyperechogenicity and duct dilation are reported as normal aging changes. Similar changes have been reported with pancreatitis in the cat. We attempted to determine if aging changes occur in the ultrasound appearance of the normal feline pancreas. The pancreas of 84 normal (based on history, physical exam, biochemical profile, and feline trypsin-like immunoreactivity and pancreatic lipase immunoreactivity concentrations) cats of varying ages was scanned. Pancreatic width at the left limb and body, pancreatic duct diameter at left limb and body, and pancreatic echogenicity compared with liver and surrounding fat were noted and compared with age and body weight. Lower and upper limits of the 95% reference intervals for pancreatic left limb width were 2.6 and 9.5 mm, and 3.5 and 8.5 mm for the pancreatic body width. There was no significant difference in pancreatic width between the left limb and body. Lower and upper limits of the 95% reference interval for the diameter of the pancreatic duct at the left limb and body were similar, and were 0.65 and 2.5 mm. There was a weak but significant linear correlation between pancreatic duct diameter and age, with increasing pancreatic duct diameter with increasing age. There was no correlation of pancreatic width with age, and no correlation of pancreatic echogenicity with age or body weight. Based on this study, feline pancreatic size and echogenicity do not change with age. Pancreatic duct diameter increases slightly with age and should not be used as a sole indicator of pancreatitis in the geriatric cat.