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Biomedical subjects

M E Herrtage

Publications and source records attributed to M E Herrtage.

At least 19 recordsLinked to original sources

DNA marker C04107 for copper toxicosis in a population of Bedlington terriers in the United Kingdom.

The DNA microsatellite marker C04107, linked to the Bedlington terrier copper toxicosis locus, is used diagnostically in the USA to detect the disease allele. This marker has been typed in Bedlington terriers of known disease status in the United Kingdom, and it is concluded that it should be useful in eradicating the disease from the breed in the UK. The marker also identified a dog which had been diagnosed on the basis of a liver biopsy as having the disease, as being unaffected; a second liver biopsy confirmed that the dog did not have copper toxicosis.

Animals

Medical management of congenital portosystemic shunts in 27 dogs--a retrospective study.

Case records of 27 dogs with medically managed congenital portosystemic shunts were reviewed. Fourteen were followed up by telephone questionnaires to the owners. Age, breed, sex, clinical signs and blood results were similar to previous studies. Weight and quality of life were stable or improved on treatment in all cases. Total serum protein concentration and alanine aminotransferase and alkaline phosphatase activities fell significantly during treatment. Fourteen dogs were euthanased, four were lost to follow-up and nine remained alive. Mean survival time for the dogs euthanased was 9.9 months. Mean follow-up period for the dogs still alive was 56.9 months and all had survived more than 36 months from diagnosis. Surviving dogs with intrahepatic shunts had a significantly shorter follow-up period than dogs with extrahepatic shunts. Two prognostic indicators were identified, age at initial signs and blood urea concentration on presentation, both correlating with survival time. It was demonstrated that a significant proportion of dogs with portosystemic shunts managed medically have a good prognosis.

Animals

Hypocortisolaemia in a Labrador retriever.

A four-year-old Labrador retriever was presented with lethargy and exercise intolerance. Clinical examination was unremarkable. A subnormal cortisol response to adrenocorticotrophin hormone (ACTH) was demonstrated (plasma cortisol concentrations before and after administration of ACTH were both below the detection limit of the assay) but plasma aldosterone concentrations were within the normal range. Endogenous plasma ACTH concentrations were high, indicating primary adrenocortical disease. Following glucocorticoid supplementation at a replacement dose (prednisolone 0.1 mg/kg) the dog made a full clinical recovery.

Addison Disease

Hyperadrenocorticism in six cats.

The case records of six cats with hyperadrenocorticism presented to the Department of Clinical Veterinary Medicine, University of Cambridge, over an 11-year period were reviewed. Signalment and clinical signs were similar to previous reports but, in contrast to other reports, only three cats had diabetes mellitus on presentation. Abdominal radiographs revealed an adrenal mass in one case, obesity in all cases but no hepatomegaly. The adrenal glands were identified ultrasonographically in three out of six cases. Clinicopathological findings were non-specific. The diabetic cats had a significantly lower serum potassium concentration than the non-diabetic cats (P < 0.05). Results of adrenocorticotrophic hormone (ACTH) stimulation tests were supportive of a diagnosis of hyperadrenocorticism in the five cats in which they were performed. Five cats had pituitary-dependent hyperadrenocorticism (PDH) and one had an adrenal tumour. Differentiation between the two forms of hyperadrenocorticism was possible preoperatively in five out of six cats. Adrenal histopathology confirmed hyperplasia in four cats and adenocarcinoma in one cat. Three cats with PDH underwent bilateral adrenalectomy and two of these cats had low, flat ACTH stimulation tests postoperatively and survived for significant periods. The cat with an adrenal tumour underwent partial unilateral adrenalectomy, maintained a positive ACTH stimulation test postoperatively and was euthanased one week after surgery.

Adrenal Cortex Function Tests

Oesophageal injury associated with the administration of an anthelmintic bolus to calves.

Six of 18 calves from a suckler herd which were dosed with a sustained-release anthelmintic bolus, using appropriate equipment, developed clinical signs related to oesophageal perforation. Two died as a direct result of the injuries sustained, one required surgical removal of the paraoesophageal bolus and the remaining three were managed medically. The calves were in the approximate weight range advised by the manufacturers as suitable for dosing, but some were younger than the minimum recommended age. These animals were of a fractious nature having been relatively little handed.

Animals

Use of ultrasonography in the diagnosis of tracheal collapse.

Ultrasonographic imaging of the cervical trachea was performed with the neck in both a neutral and a hyperextended position in 10 dogs with tracheal collapse. Tracheoscopy was used to confirm a diagnosis of tracheal collapse. The ultrasound investigation was repeated in 10 dogs of similar size but without tracheal abnormality. The ultrasonographic findings of the affected dogs were compared with those of the normal group and showed an alteration in the shape of the tracheal lumen in the ventrodorsal projection. This study highlights the possibility of identifying changes in the shape of the tracheal lumen during ultrasound investigations as an aid to the diagnosis of tracheal collapse.

Animals

Thyroid-stimulating hormone and total thyroxine concentrations in euthyroid, sick euthyroid and hypothyroid dogs.

Canine thyroid-stimulating hormone (cTSH) was measured in a variety of clinical cases (n = 72). The cases were classified as euthyroid, sick euthyroid, hypothyroid or hypothyroid on nonthyroidal therapy on the basis of their history, clinical signs, laboratory results (including total thyroxine concentrations and, where indicated, thyroid-releasing hormone [TRH] stimulation tests) and response to appropriate therapy. Additional samples were taken during some of the TRH stimulation tests to measure the response of cTSH concentrations following TRH administration. A reference range (0 to 0.41 ng/ml) was calculated from the basal concentrations of cTSH in a group of 41 euthyroid dogs. Six of nine cases of confirmed hypothyroidism had basal cTSH concentrations above the reference range, whereas the remainder were within the normal range. One of these three remaining cases was a pituitary dwarf and did not show a rise in cTSH concentration following TRH stimulation. In contrast, only one of a group of six hypothyroid dogs that had been on non-thyroidal treatment within the previous four weeks had increased concentrations of basal cTSH. This study also found that five of a group of 16 dogs with sick euthyroid syndrome had increased cTSH concentrations. It was concluded that cTSH measurements are a useful additional diagnostic test in cases of suspected hypothyroidism in dogs but that dynamic testing is still required to confirm the diagnosis of hypothyroidism.

Animals

Role of chronic disseminated intravascular coagulation in a case of canine angiostrongylosis.

A dog whose major clinical signs suggested a coagulopathy, is described. The dog had a history of bleeding episodes and had a severe regenerative anaemia. By using specific factor assays, the coagulopathy was found to be due to a consumptive intravascular process that resembled chronic disseminated intravascular coagulation. Subsequent investigations identified Angiostrongylus vasorum as the cause.

Anemia

The molecular defect underlying canine fucosidosis.

Fucosidosis is a lysosomal storage disease which affects humans and English springer spaniel dogs. The disease is recessively inherited in both species and results from a deficiency of the enzyme alpha-L-fucosidase. We have recently cloned and sequenced the canine fucosidase gene (EMBL sequence admission number X92448 (cDNA) and X92671-X92678 (individual exonic data)). The gene spans 12 kb and consists of eight exons. SSCP based mutation analysis of affected animals was carried out on the coding region of this gene both with exonic primers, and intronic primer pairs for each exon. A 14 base pair deletion of the cDNA was identified at the 3' end of exon 1 in fucosidosis affected animals. Surprisingly, PCR based genomic cloning of DNA from these animals showed an identical deletion in this DNA, ending at the start of intron 1. This change causes a frameshift and, in consequence, 25 novel codons are transcribed in exon 2 before the first of two adjacent premature stop codons is encountered.

Animals

Use of ACTH stimulation tests to monitor the treatment of canine hyperadrenocorticism.

The case histories of 60 dogs with hyperadrenocorticism were reviewed. Fifty-four of the dogs were treated with mitotane at a mean daily dose rate of 48.8 mg/kg (range 25.6 to 84 mg/kg) for between four and 21 days. The mean weekly maintenance dose of mitotane was 48.8 mg/kg. An adrenocorticotrophic hormone (ACTH) stimulation test was performed before the treatment began, and in 30 cases at the end of the induction course, and the response to ACTH was measured at regular intervals thereafter. Nine of the treated dogs developed complete hypoadrenocorticism during treatment and required permanent mineralocorticoid replacement therapy. Twelve of the dogs had normal responses to an ACTH stimulation test before treatment, and the diagnosis of hyperadrenocorticism was based on the result of a low-dose dexamethasone suppression test. These 12 dogs had consistently lower cortisol levels before and after stimulation with ACTH and four of them developed complete hypoadrenocorticism. In general the clinical signs were well controlled when the cortisol levels were less than 105 nmol/litre before and after the stimulation test. Dogs in which the clinical signs recurred had cortisol levels between 210 and 580 nmol/litre after the test, a level which is within the normal pretreatment range. Twenty-seven of the treated dogs died and six of these deaths were attributable directly to the disease or therapy. The median survival time of the 54 treated dogs was 30 months; eight dogs died during the first 16 weeks of treatment, and the dogs which survived this period had a median survival time of 39 months (mean 50 months).

Adrenal Cortex Function Tests

Intracranial haemorrhage in a dobermann puppy with von Willebrand's disease.

Neurological examination of a lethargic, ataxic 12-week-old dobermann revealed decreased conscious proprioception in all its limbs. Haematological examination revealed a low platelet count. Cytological examination of a sample of cerebrospinal fluid revealed evidence of haemorrhage and chronic inflammation. The levels of von Willebrand's factor antigen were extremely low. Skull radiographs were consistent with mild hydrocephalus. Treatment resulted in little clinical improvement and the animal was euthanased. Post mortem examination of the brain revealed an internal hydrocephalus with haemorrhage into the ventricles. It was considered that the animal had suffered severe intracranial haemorrhage as a result of its low level of von Willebrand's factor antigen and that the bleeding may have been potentiated by the low platelet count.

Animals

Echocardiographic measurements of cardiac dimensions in normal ponies and horses.

Echocardiographic examinations were performed on 41 clinically normal small ponies, large ponies and horses. Using standardised two-dimensional (2-D) echocardiographic images to guide M-mode studies, the interventricular septal thickness, left ventricular internal dimension and left ventricular wall in systole and diastole, and aortic diameter in diastole were measured. Normal values for these echocardiographic dimensions were obtained across a wide range of bodyweights. Although there was a trend for echocardiographic dimensions to increase with bodyweight across the whole range of animals examined, little or no linear correlation was found between dimensions and bodyweight within the small pony, large pony and horse groups.

Aging

Von Willebrand's disease in dogs in the United Kingdom.

An assay for the measurement of von Willebrand factor antigen has been established. In a period of 18 months, 13 dogs have been identified as suffering from von Willebrand's disease. The affected animals had levels of von Willebrand factor antigen which ranged from undetectable to 43 per cent of normal. Factor VIII levels were also reduced. Haemorrhagic episodes were usually associated with trauma or surgery, and often required transfusion with fresh blood or plasma to arrest haemorrhage.

Animals

Recognition of 'trembler', a hypomyelinating condition in the Bernese mountain dog.

An account is given of a hypomyelinating condition, 'trembler', in the Bernese mountain dog. The condition is manifested clinically as a tremor of the limbs and head which becomes more intense with excitement or stress and which disappears with sleep. The tremor, which is first noticeable between two and eight weeks old, may persist throughout life but decline with age. Examination of plastic embedded tissue obtained post mortem from two, nine-week-old animals showed hypomyelination of the spinal cord. Preliminary examination of breeding data suggests that the condition may be inherited as an autosomal recessive.

Animals