PARAKERATOSIS IN DOMESTIC ANIMALS
Zinc is an essential component of many enzyme systems, including those related to protein and carbohydrate metabolism, and is essential for maintaining a healthy coat and skin.Zinc is normally absorbed from the intestine at approximately 20-30% efficiency and competes with copper, iron and calcium for absorption.
Zinc deficiency may occur because of inadequate intake or availability, malabsorption or increased rates of loss from the organism.Decreased zinc availability has been seen in certain dog foods containing excessive levels of phytate which inteferes with zinc absorption.Zinc deficiency is mainly seen in dogs and pigs, sometimes in ruminants and horses.
Ruminal parakeratosis refers to hardening of ruminal papillae and is associated with feeding a high-concentrate diet to ruminants. So what does the rumen tell us about parakeratosis?
A low pH and increased volatile fatty acid (VFA) production in the rumen causes lesions that eventually cause the rumen papillae to keratinise (harden) and clump together.
In ruminants, the forestomach consists of the rumen, reticulum and omasum. The internal surface (cutaneous mucous membrane) of the forestomach forms papillae, or folds, that are characteristic for each division. Rumen papillae vary in size and shape e.g. the mucosa of the reticulum has a honeycomb structure, while the omasum has broad longitudinal folds called leaves.
The ruminal stratified squamous epithelium is composed of four distinct layers with multiple functions . The stratum basale and stratum spinosum have functional mitochondria that contribute to the metabolic functions of the ruminal epithelium such as the production of ketones from short-chain fatty acids. The stratum granulosum is characterised by junctional complexes called desmosomes, acting as the permeability barrier of the ruminal epithelium.intestinal stratified squamous epithelium.
What does the rumen tell us about parakeratosis?
When a ruminant is fed dietary grains, the production of VFA increases, and the rumen adapts by increasing the size of the papillae to maximise the surface area for fatty acid absorption. Under certain circumstances when the papillae increase in size, some papillae harden due to excessive epithelial proliferation with keratinisation – also known as parakeratosis. These papillae adhere together and form bundles that entrap food particles and bacteria . The abnormal epithelium and clusters of papillae decrease the efficiency of VFA absorption, causing poorer feed efficiencies.It is speculated that causes of parakeratosis other than chronic acidosis include feed pelleting, a lack of roughage, and deficiencies of vitamin A and zinc.
Cure and prevention
Clinical signs of ruminal parakeratosis are often vague and difficult to pinpoint without a visual (macroscopical) confirmation of the lesions. Clinical signs include reduced feed intake, poor production, laminitis, liver abscesses, and diarrhoea. Clinically affected animals can be treated for acidosis to decrease the incidence of ruminal parakeratosis but the prognosis is poor.
Ruminal parakeratosis can rather be prevented by proper adaptation to concentrate rations, by proper feed bunk management (especially after rain or periods where animals stand without feed), the use of ionophores to decrease the number of lactic acid-producing bacteria, and provision of adequate fiber in the ration.
The key take-home message is to prevent ruminal acidosis. This will ensure that rumen papillae and microbes will stay healthy and effective and production will be optimised.
Clinical signs
Pigs present with a disease called parakeratosis which appears as circumscribed reddened papules and plaques, thick crusting and scaling, fissures along ventral abdomen and medial thighs. Sometimes the condition is generalised and pigs may show mild lethargy, anorexia and depression. The skin lesions may resemble those caused by Staphylococcus hyicus however this usually occurs in younger piglets.
There is commonly secondary bacterial dermatitis which can complicate the diagnosis.
In dogs, a marginal deficiency may result solely in skin changes which are very noticeable to the owner. Zinc-responsive dermatosis is commonly seen in Siberian Huskies and Alaskan Malamutes and is characterised by scales and crusts around mouth, chin, eyes, joints, prepuce, scrotum and vulva.
In rapidly growing puppies, there will be scaly plaques on the skin, nasal planum and foot pads.
Canine zinc deficiency has also been described as producing ocular signs of mucopurulent exudation, blepharitis and keratitis.
Severe zinc deficiency will present as poor growth, anorexia, testicular atrophy and emaciation.
In ruminants, there is alopecia, crusts and scales on face, neck and distal extremities and mucocutaneous junctions. Low zinc status leads to lower quality milk and increased incidence of mastitis
In foals, zinc deficiency causes reduced growth rate, anorexia, cutaneous lesions on the lower extremities and alopecia.
Diagnosis
Clinical signs, skin biopsies and low serum levels of zinc and alkaline phosphatase will help to confirm a diagnosis.
Microscopically there is:
in pigs: parakeratosis, acantosis, pseudoepitheliomatous hyperplasia, hypergranulosis
in dogs: diffuse hyperkeratosis extending to follicles, superficial perivascular dermatitis with eosinophils
Treatment
Pigs: zinc should be supplemented in the diet and calcium corrected in case it is affecting zinc absorption. Rapid recovery will follow.
Dogs: in fast growing puppies few a zinc-deficient diet or excessive calcium or phytates, zinc should be supplemented and the diet corrected.
In adult dogs such as the Husky and Malamute, zinc should also be supplemented and this may have to continue indefinitely to avoid relapses. Sometimes intravenous supplementation is necessary initially.
In ruminants, zinc supplementation can increase reproductive performance by increasing conception rate. There is also an improvement in hoof hardness and less white line disease.
Foals usually respond well to zinc supplementation.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
Reference-On Request.
