Osteochondrodysplasia in Scottish Fold cats

OBJECTIVE: To better characterise the bone and joint problems which can develop in Scottish Fold cats. DESIGN: Retrospective study of cases seen in five veterinary clinics and radiographic survey of cats in a cattery. RESULTS: Six Scottish Fold cats (four castrated males, two spayed females) aged between 5 months and 6 years were presented for signs of skeletal disease including lameness, reluctance to jump, a stiff stilted gait, short misshapen distal limbs, swelling of plantar tarsometatarsal regions and short thick inflexible tails. A further four cases (one male, three females, 15 months to 11 years) were identified by radiographic screening of a cattery. A diagnosis of osteochondrodysplasia was based on characteristic radiological findings including irregularity in the size and shape of tarsal, carpal, metatarsal and metacarpal bones, phalanges and caudal vertebrae, narrowed joint spaces, and progressive new bone formation around joints of distal limbs with diffuse osteopenia of adjacent bone. A plantar exostosis caudal to the calcaneus was present in advanced cases. In all nine cases where pedigree information was available, affected cats allegedly originated from the mating of a Scottish Fold to a cat with normal ears. The severity and time of onset of physical signs, and rate of progression and extent of radiographic abnormalities, varied from case to case. Limited histological observations suggested the underlying problem may be an osteochondrodysplasia, related to inadequate cartilage maturation. Clinical signs were ameliorated by administration of pentosan subcutaneously in two of three cats in which it was trailed, and one of these also benefited from an oral glycosaminoglycan preparation. CONCLUSIONS: Clinical and radiological findings were ascribed to defective maturation and function of cartilage, particularly in the distal limbs, ears and tail. As all Scottish Fold cats suffered from osteochondrodysplasia of some degree, the best solution would be to avoid using fold-eared cats for breeding and instead use Scottish shorthairs.     

Osteochondrodysplasia in Scottish Fold cross-breed cats

Two Scottish Fold mixed cats are described in this report. Case 1 is a mixed Scottish Fold and Munchkin cat. Extremities of this cat resembled the Munchkin cat, while the ear pinna were folded forward like the Scottish Fold cat. Case 2 is a mixed Scottish Fold and American Curl cat. The ear pinna were curled caudally like the American Curl. Severe exostosis in the hind leg was observed in radiographs taken around one year of age in both cats. Both cats were dominant homozygous for c.1024G>T of the transient receptor potential vanilloid 4 gene, responsible for osteochondrodysplasia in the Scottish Fold cat. Cross breeding with Scottish Fold cats could produce unknown phenotypes, and should be avoided.     

Incomplete dominant osteochondrodysplasia in heterozygous Scottish Fold cats

This report describes an autosomal incomplete dominant pattern of inheritance for osteochondrodysplasia in the Scottish Fold cats. A three-generation pedigree was analysed. Cats with folded ears were mated with cats with normal ears. All cats with folded ears, which were presumably heterozygous for the mutated allele, developed osteochondrodysplasia in distal fore- and hindlimbs but not in other bones, including the tail in which bone deformity had been demonstrated in previous studies. The severity of the skeletal lesions of osteochondrodysplasia was different in each affected cat. Most of the cats with severe osteochondrodysplasia showed some clinical signs, but cats with mild disease were clinically unaffected. All Scottish Fold-related cats with folded-ear phenotype, even if heterozygotes, suffered from some degree of osteochondrodysplasia of the distal limbs.     

苏格兰折耳猫骨软骨发育不良的诊疗体会

苏格兰折耳猫骨软骨发育不良也称为苏格兰折耳猫骨营养不良,是影响骨骼生长和关节软骨形成、导致四肢远端和尾部畸形的一种遗传性疾病。一例疑似病例中患畜主要表现为双侧后肢跗关节处肿胀,有疼痛感,爪部、尾部变短、厚,弯曲不灵活。经血常规和影像学检查确诊为苏格兰折耳猫骨软骨发育不良。通过一段时间药物治疗,病情好转,后肢可以着地走路。     

Osteochondrodysplasia in bull terrier littermates

A four-month-old male bull terrier with an abnormal hindquarter gait was found to have changes suggesting nutritional secondary hyperparathyroidism, together with unusual large foci of non-ossified material in both femoral necks and similar smaller foci in metaphyses of several long bones. Abnormal cartilage was found in the one femoral neck examined at autopsy six weeks later, with features suggesting impaired vascular remodelling of cartilage due to failure of chondrocyte maturation. Similar clinical and radiographic abnormalities were found in three littermates (one male, two females), but not the dam. The status of six other littermates and the sire is unknown. The femoral neck lesions had healed in two pups re-examined eight months later, but some limb bones remained abnormal in shape. The abnormalities in affected pups suggested osteochondrodysplasia.     

Macrophakia in three cats

This report describes three cases of bilateral macrophakia in 3-, 5-, and 9-year-old cats, respectively. All cats were presented because of visual deficits. Ophthalmic examination revealed macrophakia (the vitreous was replaced by the lens) and retinal changes (tapetal hyper-reflectivity, attenuation of retinal vessels, and retinal folds) in all cats. In addition, bilateral subconjunctival orbital fat prolapse in one cat and microphthalmos in another cat were present. To confirm the ophthalmologic diagnosis of macrophakia, gross pathology examination in one cat and ultrasound examination in another cat were performed.     

Cutaneous cryptococcosis in three cats

Cutaneous cryptococcosis was diagnosed in 3 cats. No other organ involvement was found. One cat has remained healthy after surgical excision of the cryptococcal skin lesion. One cat was euthanatized after diagnosis. The third cat was treated successfully with a 5-month course of ketoconazole.     

Fat malassimilation in three cats

Three cats were thin despite eating well. Steatorrhoea was confirmed in each by 72-hour fat assimilation tests. Fat digestibility in all 3 increased twofold when the diet was supplemented with pancreatic enzymes, suggesting the possibility of exocrine pancreatic insufficiency. However, examination of stained faecal smears gave evidence of both maldigestion and malabsorption of fat, without maldigestion of starch, and only one case had indications of protein maldigestion. In the latter cat, fat digestibility normalised with pancreatic enzyme supplementation and exocrine pancreatic insufficiency was considered likely. However, at post-mortem examination enteropathy and pancreatitis, but not exocrine pancreatic insufficiency, were found. The cause of fat malassimilation in these cats was unknown. The evaluation of malassimilation in cats is difficult because investigative tests used in other species are either unsuitable or have not been evaluated in cats.     

Hemophilia A in three unrelated cats

Factor VIII deficiency, consistent with hemophilia A, was detected in 3 unrelated male domestic short-haired cats. Clinical history of each case differed and illustrated the spectrum of clinical manifestations of this disease in cats. Clinical expression of feline hemophilia A was similar to that of man and other animals, in which the degree of factor VIII deficiency tends to determine the severity and frequency of bleeding. All 3 cats had severe protracted bleeding after minor surgical procedures. Hemorrhage was eventually controlled in each case by transfusions of fresh whole blood.     

Intrathoracic tracheal avulsion in three cats

The surgical repair of complete intrathoracic tracheal avulsion in three cats is described. The initial presenting signs included dyspnoea, exercise intolerance and exertional cyanosis. Diagnosis was based upon the clinical signs, survey radiography and tracheal endoscopy. The ruptures were repaired via a right lateral thoracotomy made at the third or fourth intercostal interspace. Abnormal trachea was resected and a standard tracheal anastomosis was performed. Surgical results were considered excellent in all cases.     

Congenital tarsal hyperextension in three cats

CASE DESCRIPTION: 3 kittens were examined because of a malformation affecting the hind limbs, resulting in an inability to bear weight or ambulate normally. CLINICAL FINDINGS: 2 kittens were younger than 6 weeks of age, and 1 was 4 months of age at the time of initial examination. The congenital abnormality was characterized by severe tarsal hyperextension in which weight was borne on the cranial aspect of the tarsus, and the plantar surface of the metatarsus faced dorsally. In 2 kittens, the condition affected both hind limbs, and in the older kitten, the condition was unilateral. In the 2 kittens in which radiographs were obtained, no bone abnormalities were detected. Full-cylinder fiberglass casts were applied and changed weekly to accommodate growth. Owners administered physical therapy after final cast removal. TREATMENT AND OUTCOME: Conservative management involving external coaptation and physical therapy led to favorable results in all 3 cats. CLINICAL RELEVANCE: Although further studies are needed to determine the etiology of the disorder, affected kittens may be successfully treated with conservative management. Owners should be committed to the necessity for returning cats for serial cast changes, care for pressure sores, and administration of physical therapy after cast removal.     

Mitral valve stenosis in three cats

Two-dimensional and M-mode echocardiography were used to diagnose mitral stenosis in two cats with heart failure. This appeared to be related to mitral valve complex malformation. Ultrasound findings included thickened mitral valve leaflets with inhibited mobility, reduced mitral valve orifice size, abnormal upward (cranial) motion of the caudal mitral leaflet during diastole and severe left atrial enlargement. Colour-flow and spectral Doppler imaging helped characterise this condition. Colour-flow Doppler mapping showed turbulence and increased mitral filling velocity (aliasing) at the site of stenosis and related jets of mitral regurgitation. Spectral Doppler recordings showed increased diastolic mitral filling velocities with spectral broadening and prolonged pressure half-time. Mitral stenosis should be included in the differential diagnosis of cats with severe left atrial enlargement when congenital or acquired mitral valve disease is detected; it may represent an advanced form of mitral valve complex malformation in some cases.     

Monocytic leukemia in three cats.

Of 3 cats with monocytic leukemia, 1 responded favorably to treatment with cytosine arabinoside. With supportive therapy, it lived 78 days from the time of diagnosis, at which time it developed dyspnea and signs of toxicosis and died. The other 2 cats did not respond to treatment and died 4 and 16 days from time of diagnosis. Prior to death, they were bleeding from injection sites, and their blood had greater than 200,000 WBC/mm3. Necropsy of those 2 cats revealed extensive perivascular hemorrhagic infarcts within the cerebellum, medulla, and cerebrum.     

Idiopathic sterile pyogranuloma in three domestic cats

Pyogranulomatous inflammation has been extensively described in cats, in particular in cases of feline infectious peritonitis and also associated with Mycobacteria, Actinomyces, Nocardia, Rhodococcus and fungal infections. Idiopathic sterile pyogranulomatous dermatitis has also been described. In this case series we describe the clinical presentation, histopathology and outcome of three cases of feline idiopathic sterile steroid-responsive pyogranuloma with different presentation and different locations of the lesion, but with the common feature of having a mass with no superficial skin involvement.     

Benign cranial mediastinal lesions in three cats

Cranial mediastinal lesions were detected in three cats, associated with respiratory impairment (case one), spontaneous pneumothorax (case two) and myasthenia gravis (case three), respectively. On gross and histological examination, the first case was considered either a lymphangioma or a branchial cystic mass of the thymic region of the mediastinum; a cystic lesion was suggested by sonographic detection of multiple anechoic cavitations within a circumscribed mass, while fine needle aspiration cytology excluded lymphosarcoma. The second case was diagnosed histologically as a cystic thymoma, but the third case was not examined microscopically. The masses were amenable to surgical excision in the first two cats, while this proved unnecessary in the third case because of resolution following treatment with dexamethasone. Corticosteroid responsiveness was unhelpful in distinguishing between these benign lesions and lymphosarcoma, as in two cases there was a partial or complete response to dosing with prednisolone or dexamethasone. These cases are presented to emphasise that conditions other than lymphosarcoma can produce cranial mediastinal lesions in cats, and that the prognosis for surgical treatment of lymphangiomas, multilocular thymic cysts and cystic thymomas can be excellent.     

Acute tularemia in three domestic cats.

Acute Francisella tularensis infection in 3 domestic cats was presumptively diagnosed on the basis of clinical signs and lesions and confirmed by culturing or immunofluorescent demonstration of the organism. Clinical findings include marked signs of depression, oral/lingual ulceration, regional or generalized lymphadenomegaly, hepatosplenomegaly, panleukopenia with severe toxic change of neutrophils, and hyperbilirubinemia with bilirubinuria. Lesions found at necropsy included icterus, oropharyngeal and lingual ulceration, multiple foci of necrosis in lymph nodes, spleen, liver, and lung, and severe segmental or diffuse enterocolitis. Results of serologic testing for F tularensis was positive in only 1 of the 3 cats. The organism was cultured aerobically from several tissues, including aspirated bone marrow obtained before death in 1 cat. Results of an indirect fluorescent antibody test, performed on fresh and formalin-fixed tissues of all cats, were positive. Because of the severe clinical course, opportunity to evaluate therapeutic regimens was not possible. Until now, confirmed diagnosis of feline tularemia only has been made retrospectively, in instances when cats were suspected to have transmitted infection to human beings in whom the primary diagnosis was made. The findings in this report provide a basis for presumptive diagnosis that will help to minimize public health risk associated with this potentially fatal zoonotic disease.