Mark Collett

Dr. Mark Collett

Massey University, New Zealand
orcid

Research Focus & Metrics

Academic Career Length

47Years (1980-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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25 August 2008 in Journal of Veterinary Internal Medicine
Verified
Journal Article
Open access
PDF file
MWM D Willard
M D Willard
JMJ. Mansell
J. Mansell
GFGeoff Fosgate
Geoff Fosgate
MGM. Gualtieri
M. Gualtieri
DOD. Olivero
D. Olivero
RWR.J. Washabau
R.J. Washabau
Background: The quality of histopathology slides of endoscopic biopsies from different laboratories varies, but the effect of biopsy quality on outcome is unknown. Hypothesis: The ability to demonstrate a histologic lesion in the stomach or duodenum of a dog or cat is affected by the quality of endoscopic biopsy samples submitted. More endoscopic samples are needed to find a lesion in poor-quality tissue specimens. Animals: Tissues from 99 dogs and 51 cats were examined as clinical cases at 8 veterinary institutions or practices in 5 countries. Methods: Histopathology slides from sequential cases that underwent endoscopic biopsy were submitted by participating institutions. Quality of the histologic section of tissue (inadequate, marginal, adequate), type of lesion (lymphangiectasia, crypt lesion, villus blunting, cellular infiltrate), and severity of lesion (normal, mild, moderate, severe) were determined. Sensitivity of different quality tissue samples for finding different lesions was determined. Results: Fewer samples were required from dogs for diagnosis as the quality of the sample improved from inadequate to marginal to adequate. Duodenal lesions in cats displayed the same trend except for moderate duodenal infiltrates for which quality of tissue sample made no difference. Gastric lesions in dogs and mild gastric lesions in cats had the same trend, whereas the number of tissue samples needed to diagnose moderately severe gastric lesions in cats was not affected by the quality of tissue sample. Conclusions and Clinical Importance: The quality of endoscopically obtained tissue samples has a profound effect on their sensitivity for identifying certain lesions, and there are differences between biopsies of canine and feline tissues.

10 July 2000 in Journal of the South African Veterinary Association
Verified
Journal Article
Open access
PDF file
MCMark Collett
Mark Collett
A questionnaire, designed to obtain qualitative information on a number of variables concerning canine babesiosis (biliary fever) in South Africa, was sent to 510 veterinary practices in late 1993. Of the 157 practices that responded, all were presented with cases of babesiosis and most were situated in Gauteng, the Western Cape and KwaZulu-Natal. Apart from the Western Cape, a winter-rainfall region, the prevalence of babesiosis cases in dogs was highest in summer. Most of the respondent practices treated between 1000 and 5000 sick dogs that included 100 to 500 babesiosis cases each year. Respondents identified cerebral babesiosis, enterorrhagia, 'red' or haemoconcentrated babesiosis, acute renal failure and pulmonary babesiosis or 'shock lung', amongst others, as the most prevalent forms of complicated ('atypical') babesiosis. Diminazene, imidocarb and trypan blue were the most popular antibabesials. Trypan blue was most often used in shocked patients, whereas diminazene and imidocarb were preferred when there was a high parasitaemia in the absence of shock. At least 19 antibabesial treatment regimens were used in practices. These comprised the use of single doses of antibabesial drugs; split doses with repeat injections, and combined drug variations, some of which are undesirable due to possible sterilisation of Babesia infection or potential toxicity. Side-effects were most commonly associated with imidocarb use. Ninety-six percent of respondents used supportive treatment (e.g. corticosteroids, vitamins and 'liver support') in all cases of babesiosis. The use of blood transfusion as supportive treatment varied according to practice and severity of the case. Most practices never cross-matched blood to be transfused, and transfusion reactions were rare. Diminazene was most frequently incriminated in cases where drug 'resistance' or relapses occurred. Cerebral and 'red' cases resulted in high mortality. Treatment of babesiosis costs the dog-owning public in South Africa more than R20 million each year. Information on the distribution and possible complicating role of Ehrlichia canis was obtained. Development of a vaccine was the first research priority identified.

1 October 2000 in New Zealand Veterinary Journal
Verified
Journal Article
Closed access
RJR.D. Jolly
R.D. Jolly
FAF.J. Allan
F.J. Allan
MCMark Collett
Mark Collett
TRT. Rozaklis
T. Rozaklis
VMV.J. Muller
V.J. Muller
JHJ.J. Hopwood
J.J. Hopwood
Aim: To investigate the nature of a progressive ataxia in a New Zealand Huntaway dog. Methods: The affected dog was examined clinically before being humanely killed and necropsied. Selected tissues were submitted to light and electron microscopy and to biochemical analyses. Results: The histological lesions were interpreted as indicative of one of the forms of mucopolysaccharidosis type-III (dMPS-III), a lysosomal storage disease. Biochemically there was a deficiency of heparan sulphamidase. All the heparan sulphate chains had non-reducing-end glucosamine-N-sulphate residues. Conclusion: The disease is dMPS-IIIA (Sanfilippo syndrome). An autosomal recessive mode of inheritance can be provisionally assumed from the nature of this disease in other species.

1 January 2010 in Journal of Veterinary Internal Medicine
Verified
Journal Article
Open access
PDF file
MWM D Willard
M D Willard
GMG.E. Moore
G.E. Moore
BDB.D. Denton
B.D. Denton
MDM.J. Day
M.J. Day
JMJ. Mansell
J. Mansell
RWR.J. Washabau
R.J. Washabau
Background: Prior studies failed to detect significant association between hypoalbuminemia and small intestinal lesions. Hypothesis: Use of pictorial templates will enhance consistency of interpathologist interpretation and identification of intestinal lesions associated with hypoalbuminemia. Animals: Tissues from 62 dogs and 25 cats examined as clinical cases at 7 referral veterinary practices in 4 countries. Methods: Retrospective, observational study. Histopathology slides from sequential cases undergoing endoscopic biopsy were examined by 4 pathologists by pictorial templates. Changes for 9 microscopic features were recorded as normal, mild, moderate or severe, and 2‐ and 4‐point scales were tested for consistency of interpretation. Logistic regression models determined odds ratios (OR) of histologic lesions being associated with hypoalbuminemia while κ statistics determined agreement between pathologists on histologic lesions. Results: There was poor agreement (κ=−0.013 to 0.3) between pathologists, and institution of origin of slides had effect (κ= 1.0 for 3 of 4 lesions on slides from Institution 5) on agreement between pathologists on selected histologic features. Using 2 point as opposed to 4‐point grading scale increased agreement between pathologists (maximum κ= 0.69 using 4‐point scale versus maximum κ= 1.0 using 2‐point scale). Significant association (P= .019– .04; 95% OR = 3.14–10.84) between lacteal dilation and hypoalbuminemia was found by 3 pathologists. Conclusions and Clinical Importance: Substantial inconsistency between pathologists remains despite use of pictorial template because of differences in slide processing. Distinguishing between mild and moderate lesions might be important source of the disagreement among pathologists.

29 March 2014 in Journal of Agricultural and Food Chemistry
Verified
Journal Article
Closed access
MCMark Collett
Mark Collett
BSBryan L. Stegelmeier
Bryan L. Stegelmeier
BTBrian A. Tapper
Brian A. Tapper

31 March 2006 in Small Ruminant Research
Verified
Journal Article
Closed access
DWD.M. West
D.M. West
WPWilliam E. Pomroy
William E. Pomroy
MCMark Collett
Mark Collett
FHF.I. Hill
F.I. Hill
ARA.L. Ridler
A.L. Ridler
RPR.S. Pattison
R.S. Pattison