Biomedical subjects
Publications and source records attributed to G S Allan.
Peritoneopericardial diaphragmatic hernia is a common incidental finding in cats and is rarely symptomatic. The case report described herein presented with dyspnoea secondary to incarceration of hepatic cysts within the pericardial space of a cat with a peritoneopericardial diaphragmatic hernia.
Feline joint disorders are often overlooked, possibly because cats are extremely agile and appear to cope with pathologic changes within their joints better than their canine counterparts. There is a growing awareness that osteoarthritis occurs more frequently than previously anticipated in cats, and recently we have seen the emergence of hip dysplasia as an entity of concern in some purebred cats. There are also several poorly understood conditions that affect the joints of cats, such as synovial osteochondromatosis, that invite further study. In recent years we have seen an expansion in the knowledge of immune-mediated and infectious arthropathies and their inter-relationship with infective agents. This article describes the radiographic changes seen in many of the currently recognized joint disorders of domestic cats.
Between 1990 and 1997 vegetative endocarditis was diagnosed in six neutered cats (three males, three females) aged between 3 and 9 years. Two cats were purebred (one Persian and one Tonkinese), the remaining four being domestic short haired cats. The diagnosis was made using echocardiography (five cases) or at necropsy (one case). Concurrent involvement of the aortic and mitral valve was noted in four cats, the aortic valve alone was affected in one case, and the tricuspid valve in another. A likely microbiological diagnosis was obtained in three cats: a Bartonella species in two cats based on positive blood culture and a Streptococcus species in one cat based on Gram stain of valve lesions at necropsy. In another cat, Gram-positive cocci were demonstrated histologically in tricuspid vegetations. Invariably, cats had signs of congestive heart failure (left-sided in five cats, right-sided in one), and this was the major factor contributing to mortality in four cases. Signs referable to sepsis were prominent in only two patients. Appropriate medical therapy, consisting of antimicrobials and drugs to treat congestive heart failure, resulted in survival for 5 and 11 months, respectively, in two cases. The other cats died within 2 weeks of diagnosis, including two which received aggressive treatment in hospital.
Intra-abdominal cryptococcosis was diagnosed in two young dogs. The first, an entire male border collie, was presented with vomiting. An abdominal mass detected during physical examination proved to be cryptococcal mesenteric lymphadenitis on exploratory laparotomy. The second dog, a female neutered giant schnauzer, was presented with neurological signs suggestive of encephalopathy. Intestinal cryptococcal granulomas were detected in an extensive diagnostic investigation which included abdominal ultrasonography. The gastrointestinal tract was considered the most likely portal of entry for cryptococcal organisms in both cases. Both dogs were treated using surgery and multiagent antifungal chemotherapy. The first case succumbed despite therapy, while the second dog was treated successfully as gauged by return to clinical normality and a substantial decline in the cryptococcal antigen titre which continued to fall after cessation of treatment.
Mycobacterium thermoresistibile was isolated in pure culture from ultrasound-guided pulmonary aspirates taken from a young cat with severe, chronic, pyogranulomatous pneumonia. Thoracic radiography and ultrasonography before therapy demonstrated severe diffuse alveolar disease. Twelve months combination therapy with doxycycline, rifampicin and clarithromycin resolved the infection. Thoracic radiographs taken at the completion of therapy showed multifocal pulmonary mineralisation. M thermoresistibile has been infrequently reported as a human or animal pathogen. This is the first reported pulmonary infection by M thermoresistibile in a cat and documents the successful treatment of the organism in a feline patient.
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.
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Rickets was diagnosed in six 14-week-old racing greyhound littermates presented with musculoskeletal disease. Physical findings included listlessness, profound muscle weakness, lameness, lateral bowing of the antebrachii and focal hard swellings proximal to the tarsi and carpi. Radiological findings included generalised osteopenia, axial and radial thickening of growth plates, and "cupping' of the adjacent metaphyses; the distal ulnar growth plates were most severely and consistently affected. The diagnosis was confirmed by demonstrating subnormal concentrations of 25-hydroxycholecalciferol in serum samples collected at admission. The pups' diet consisted of an inexpensive generic kibble formulated for adult dogs, porridge, milk, pasta, minced beef, vegetables and a small quantity of calcium carbonate powder. The pups were successfully treated by feeding a nutritionally complete, vitamin D-containing ration formulated for growing pups. Bilateral growth retardation of distal ulnar physes occurred as a sequel in one pup.
A cervical esophageal stricture was corrected in a dog by creation of a traction diverticulum. Although abnormal esophageal motility persisted in the portion of the esophagus cranial to the stricture, the clinical effects of the stricture were ameliorated by the simple surgical procedure.
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Thoracic radiographs demonstrated a needle-like foreign body within the myocardium of a three-year-old male labrador retriever examined for an unrelated illness. Six months later the dog became lethargic and inappetent. The original foreign body had not moved, and a second needle was present in the stomach. Laparotomy and gastrotomy revealed a sewing needle which had perforated the lesser curvature of the stomach and was migrating cranially. An organised fibrous band extended through the diaphragm, and it is suspected that the original myocardial foreign body had migrated from the stomach by this route.
Megaesophagus attributable to lead toxicosis was diagnosed in a 3-year-old spayed domestic shorthair cat. The cat regurgitated when it was distressed by handling, and there was clinical evidence of laryngeal and pharyngeal dysfunction. The cat had macrocytic regenerative anemia, but did not have normoblastosis or basophilic stippling of RBC. The megaesophagus, pharyngeal/laryngeal dysfunction, and anemia resolved with calcium EDTA treatment.
A 16-week-old female Rottweiler was examined because of labored breathing and abdominal distention. Ascites, hepatomegaly, and pleural effusion were detected during physical and radiographic examinations. Selective angiography revealed a stenotic lesion at the junction of the caudal vena cava and the right atrium. A fibrous diaphragm with a pin-hole orifice was observed at surgery. Clinical signs of disease resolved after successful removal of the membranous obstruction.
The infective juveniles of Trichostrongylus colubriformis can survive exposure to 0% relative humidity after desiccation at higher relative humidities. During rehydration there is a lag phase before recovery. The infective juveniles are thus capable of anhydrobiosis. Removal of the sheath does not affect desiccation survival but does affect the duration of the lag phase. Morphological changes during the lag phase are described. The appearance of birefringence in the muscle cells during the anomalous shrinkage which occurs during the lag phase is considered to reflect physiological changes necessary for the recovery of normal muscle function.
1. All free-living stages of the nematode parasite of sheep, Trichostrongylus colubriformis Giles, survived exposure to freezing temperatures in contact with water, with the exception of the first-stage juvenile (J1). The third-stage juvenile (J3) was the most resistant stage. The order of relative survival of the different stages was different from that of the lowest F50 (the temperature at which 50% froze), suggesting that an ability to supercool was not the only determinant of survival. 2. The F50 was shown to be a good measure of the degree of supercooling and to extend greatly the lower size limit of organisms that could be measured. 3. The J3 uses a freeze-avoiding strategy by supercooling when in air or covered by liquid paraffin. In water it uses a mixture of freeze-avoiding and freeze-tolerant strategies, with a proportion of the population surviving freezing caused by exogenous ice nucleation. 4. Removal of the J3 sheath results in a shift from freeze avoidance to freeze tolerance, with an overall reduction in survival. A major function of the sheath may be to reduce the probability of exogenous ice nucleation.
A 12-month-old, desexed female Cocker Spaniel had intermittent bilateral foreleg lameness which was due to panosteitis of the radius and ulna. The disease was in the active 'middle' state. Endosteal and periosteal new bone formation was demonstrated by histological examination and accounted for the diffuse osteosclerotic appearance of the radial and ulnar diaphyses seen on radiographs.
Yearling heifers overfed protein, calcium and phosphorus with a feed recommended for high producing dairy cows developed osteopetrosis and skeletal malformations as a result of retarded bone resorption. Histologic and electron microscopic examinations showed that C cell hyperplasia was also present. The presence of C cell hyperplasia and osteopetrosis supported the diagnosis of hypercalcitoninism. Clinically unaffected heifers were studied by serum chemistry after 1 to 1.5 months on the same diet at age 6 months and after 3 months on an optimal diet to learn whether they showed evidence of hypercalcitoninism as expressed by retarded bone resorption and/or hypercalcitoninemia. The data indicated that bone resorption was retarded and that serum gastrin was elevated in the heifers without skeletal malformations while on the high calcium feed. The heifers were isocalcitoninemic. The data suggested that overfeeding calcium was sufficient to produce hypercalcitoninism but the rate of calcitonin secretion had not exceeded the rate of removal of calcitonin from blood by binding to tissue receptors and by metabolic degradation. Since calcitonin is rapidly removed from blood, hypercalcitoninism may occur without concomitant hypercalcitoninemia.