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Biomedical subjects

J J Vermunt

Publications and source records attributed to J J Vermunt.

31 records · Page 2Linked to original sources
PubMed1994

Observations on three outbreaks of Leptospira interrogans serovar pomona infection in lambs.

Sickness and deaths associated with leptospirosis were reported in three lamb flocks in the Manawatu region. The clinical, pathological and serological features of Leptospiru interrogans serovar pomona infection are described. The mucous membranes of affected animals were pale and jaundiced. Haemoglobinuria, haemoglobinaemia and centrilobular hepatocellular necrosis were also consistent findings. All clinically sick lambs had very high titres in the microscopic agglutination test for L. pomona. Circumstantial evidence of pigs being the source of infection was found in one of the three cases.

Journal Article↗
PubMed1992

"Subclinical" laminitis in dairy cattle.

In dairying countries worldwide, the economic importance of lameness in cattle is now recognised. Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders such as white zone lesions, sole ulcer, and heel horn erosion. The existence of subclinical laminitis was first suggested in the late 1970s by Dutch workers describing the symptoms of sole haemorrhages and yellowish-coloured, soft sole horn. In an attempt to clarify some of the confusing and often conflicting terminology, the literature on laminitis is reviewed. Disturbed haemodynamics, in particular repeated or prolonged dilation of arteriovenous anastomoses, have been implicated in the pathogenesis of both equine and bovine laminitis. Some characteristics of the vascular system of the bovine claw which may be of importance in the pathophysiology of the subclinical laminitis syndrome are therefore discussed. Clinical observations suggest that subclinical laminitis is a multifactorial disease. The different factors that are or may be involved in its aetiology vary in complexity and severity according to the management protocol of the animals. The possible involvement of subclinical laminitis in claw lesions is assessed.

Journal Article↗
PubMed1992

A macroscopic study of the vascular system of the bovine hind limb claw.

The vascular organisation of the hind limb claws from clinically normal cattle was studied using plastic corrosion casts. The proper digital artery ran dorsodistally within the interdigital space and gave off a bulbar branch to the bulb, a plantar branch to the axial aspect of the wall and sole, and a coronary artery to the coronary margin and proximal wall. The artery entered the distal phalanx at the axial foramen, coursed through the nutrient canal as the terminal arch, and emerged at the abaxial foramen to anastomose with branches of the bulbar artery. During its interosseous course, the terminal branch gave off 6-8 primary branches which provided the arterial supply to the coronary margin, axial and abaxial wall, white zone and sole. The dorsal proper digital vein and axial and abaxial proper plantar digital veins drained all venous blood from the claw. Each of these large veins arose from numerous smaller veins which joined to form the venous networks of the coronary margin, wall, sole and bulb. A large arched vein passed through the coronary cushion and formed a connection between the superficial coronary venous plexus and the intra-osseous plexus of the distal phalanx. The axial and abaxial proper plantar digital veins were connected by a vessel through the bulbar cushion. At the same level, the axial proper plantar digital veins of the lateral and medial claw were connected to each other by a large vessel through the interdigital space, situated just proximal to the distal interdigital ligaments. This resulted in the presence of a complete distal venous arch along the plantar aspects of both claws. The parietal collecting veins drained most of the venous blood from the sole, white zone and wall, and connected directly to the venous plexuses of the coronary margin and bulb. Valves occurred commonly in medium and larger calibre veins throughout the claw.

Journal Article↗
PubMed1992

A scanning electron microscopic study of the vascular system of the bovine hind limb claw.

The vascular organisation of the hind limb claws of clinically normal cattle was studied using scanning electron micrographs of plastic corrosion casts. The microvasculature of the dermal papillae and lamellae was demonstrated. A consistent vascular pattern was observed in the dermal papillae of the periople, coronary margin, sole and bulb. Ultrastructurally, the papillar vasculature consisted of a central artery and vein surrounded by a fine network of interconnected capillaries and venules. Arteriovenous anastomoses, connecting the central artery and vein, and peripherally situated arteriovenous loops were recognised in the terminal papillae of the white zone only. Arteriovenous anastomoses, focal enlargements and distension of the capillary bed were located within the interior half of the dermal lamellae. Numerous arteriovenous anastomoses were present throughout the entire dermis of the claw and were situated predominantly at the base of the dermal papillae and lamellae. The anastomoses and focal capillary enlargements may influence the blood flow in normal conditions and may play a significant role in the pathophysiology of bovine laminitis and sole ulceration.

Journal Article↗
PubMed1991

Evaluation of subclinical laminitis in a dairy herd and observations on associated nutritional and management factors.

The hind claws of 10 heifers, 10 second-calf cows, and 10 mature cows in the University of Saskatchewan's dairy herd were examined on four consecutive occasions, four and two months before calving, at calving, and two months after calving. A high prevalence of haemorrhages was observed in the sole of the claws, and these lesions were most prevalent near calving; the haemorrhages were detected in the heifers up to four months before calving. After calving, the haemorrhages tended to disappear rapidly from the claws of the heifers, but no such recovery was evident in the second calvers and mature cows. A scoring system for sole haemorrhages was developed, and the different scores were linked with sole ulcer (pododermatitis circumscripta), toe ulcer, white zone lesions, and heel erosion. Factors associated with nutrition and management, such as rapid rearing (average daily weight gain from birth to breeding greater than 800 g), the sudden introduction into the dry group after they had been confirmed pregnant, confrontation by dominant cows, and housing on concrete in a cubicle system appeared to play a role in the occurrence of haemorrhages in the claws of heifers well before calving.

Age Factors↗
PubMedDate not supplied

Predisposing factors of laminitis in cattle.

Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders. Despite intensive study, both by experiment and by clinical observation, knowledge of the precise aetiology and pathogenesis of bovine laminitis is still incomplete. It is often hypothesized that changes in the micro-circulation of the corum (dermis) of the bovine claw contribute significantly to the development of laminitis; arteriovenous anastomoses (AVAs) playing a crucial role. Many factors have been implicated as contributing causes of laminitis in cattle; the disease has a multifactorial aetiology. The cause of laminitis should be considered as a combination of predisposing factors leading to vascular (AVAs in particular) reactivity and inhibition of normal horn synthesis. Nutrition, disease, management and behaviour appear to be closely involved in the pathogenesis of bovine laminitis. The major factors predisposing to laminitis in cattle, as reported or suggested in the literature, are reviewed, including systemic disease, nutrition (barley grain, protein, carbohydrate and fibre), management (housing, bedding and exercise), calving, season, age, growth, genetics, conformation and behaviour.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Structural characteristics of the bovine claw: horn growth and wear, horn hardness and claw conformation.

Claw quality is the product of horn characteristics, claw shape and anatomy and physiology of the inner structure. This paper aims to review some of the different approaches that have been employed to evaluate claw quality. The various factors that may influence horn growth and wear are reviewed, including physiological, seasonal, nutritional, environmental, management and anatomical aspects. Horn hardness is similarly described. Claw conformation is discussed, commencing with a brief outline of the various methods used to determine claw shape and size, followed by an account of some of the factors that influence claw conformation. The clinical importance of claw conformation in cattle is considered with particular reference to lameness, longevity and production traits. Finally, the prospect of improving claw quality by selection of bulls based on claw measurements is reviewed.

Animals↗
PubMedDate not supplied

Lesions associated with subclinical laminitis of the claws of dairy calves in two management systems.

Claws of ten 6 to 7-month-old dairy calves in two management systems were examined for lesions associated with subclinical laminitis. Sole haemorrhages were found only in claws of calves maintained out of doors. No significant differences in number and severity of haemorrhages were found between left and right or lateral and medial claws, but haemorrhages were more frequent and more severe in hind claws than in front claws (P < 0.05). More haemorrhages of greater severity were present in the white zone at the toe than in all other areas of the weight-bearing surface combined (P < 0.05). No lesions of interdigital dermatitis and heel horn erosion were found in either indoor-housed or outdoor-housed calves. All calves kept indoors on deep bedding developed overgrown claws.

Animal Husbandry↗