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→Diagnosis
Uraemia is a complex disorder that affects multiple organ systems and produces a variety of clinical syndromes:
Uraemia is a complex disorder that affects multiple organ systems and produces a variety of clinical syndromes:
====Gastro-intestinal Disease====
====Gastro-intestinal Disease====
*'''Oral ulceration''' - This occurs especially at the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|fauces]] of the mouth and on the margins of the [[Oral Cavity - Tongue - Anatomy & Physiology|tongue]]. Halitosis is often a feature of this syndrome as the lesions become secondarily infected with oral bacteria such as ''[[Fusobacterium necrophorum]]''. In severe cases, there may be extensive subepithelial necrosis and sloughing of the tip of the tongue. The lesions are often very painful and contribute to the anorexia often observed in animals with chronic kidney disease. Excessive dental calculus may be evident in animals with chronic kidney disease on oral examination.
*'''[[Gastric Ulceration - all species|Gastric ulceration]]''' - This occurs for three main reasons. First, urea crosses lipid membranes freely and enters the gastro-intestinal lumen of azotaemic animals. The urea is degraded to ammonia by bacterial urease and the ammonia irritates the intestinal mucosa. This is compounded by damage to the blood vessels of the gastric submucosa by the fibrinoid necrosis that is a common feature of uraemia. Elevated serum concentrations of gastrin (which is normally metabolised in the kidney) also lead to excessive production of gastric acid from parietal cells in the stomach. Animals with gastro-duodenal ulceration may show '''anorexia''', '''vomiting''', '''haematemesis''' and [[Peritonitis - Cats and Dogs|'''peritonitis''']] and '''haemorrhage''' if the ulcers perforate. Hypergastrinaemia may also cause incompetence of the pyloric sphincter of the stomach, permitting relfux of irritant bile into the stomach. Similar processes result in the development of '''uraemic colitis'''.
*'''[[Peritonitis - Cats and Dogs|Uraemic peritonitis]]''' - This is a form of chemical [[peritonitis]] that results from inflammation of the small mesothelial blood vessels.
====Respiratory Disease====
====Respiratory Disease====
*'''[[Pulmonary Oedema|Pulmonary oedema]]''' - Damage to the small vessels of the pulmonary vasculature may result in the development of vasogenic pulmonary oedema and pleural effusion with dyspnoea, tachypnoea and coughing.
====Electrolyte and Acid/Base Imbalances====
====Electrolyte and Acid/Base Imbalances====
*'''Electrolyte imbalances''' - The failure to excrete phosphate through the damaged kidneys results in hyperphosphataemia. This electrolyte complexes with calcium and also prevents the activation of vitamin D (dihydroxycholecalciferol), resulting in hypocalcaemia. This hypocalcaemia directly stimulates the production of parathyroid hormone (PTH) to try to maintain normal blood calcium levels and, in ~10% dogs with renal failure, hypercalaemia may develop due to an alteration in the set-point at which PTH is secreted. In the remaining 90%, calcium is mobilised from bone causing '''secondary renal hyperparathyroidism''' with resorption of bone, pathological fractures and fibrous osteodystrophy of the bones of skull ('rubber jaw').
*'''Metastatic mineralisation''' - The presence of excessive blood concentrations of phosphate leads to metastatic calcification in multiple tissues, particularly the rugae of the gastric mucosa, the pulmonary parenchyma and the heart.
*'''Metabolic acidosis''' - The kidney plays a vital role in the regulation of the normal acid/base balance.
====Cardiovascular Disease====
====Cardiovascular Disease====
*'''Atrial rupture''' - Mineralisation of the atria reduces their normal compliance and renders them susceptible to rupture. The resultant haemopericardium is often fatal as it causes acute cardiac tamponade.
*'''[[Arrhythmias Overview|Arrhthymias]]'''
====Haematological Disease====
====Haematological Disease====
*'''Thrombocytopathia''' - The reduction in platelet function occur due to multiple alterations in normal [[Thrombocyte|thrombocyte]] metabolism.
*'''Anaemia''' - This occurs because the diseased kidenys produce less erythropoietin than normal and the uraemic toxins (especially PTH) decrease the lifespan of existing red blood cells. Erythrocytes may also be damaged as they pass along inflamed vessel walls, a form of microangiopathic haemolysis. Chronic gastro-intestinal haemorrhage may also result in iron deficiency.
====Neuromuscular Disease====
====Neuromuscular Disease====
*'''Neurological disease''' - The presence of extremely high concentrations of urea and creatinine may induce '''reduced conciousness''' or '''uraemic seizures''' and this is usually a terminal event. PTH has also been implicated in the development of uraemic encephalopathy, possibly due to alterations in calcium pumps. Animals may enter a so-called '''twitch-convulsive''' state where they suffer concurrent tremors, myoclonus and seizures. Peripheral neuropathies may contribute to the reduced hindlimb function that is commonly ascribed to hypokalaemic myopathy.
*'''Neurological disease''' - The presence of extremely high concentrations of urea and creatinine may induce '''reduced conciousness''' or '''uraemic seizures''' and this is usually a terminal event. PTH has also been implicated in the development of uraemic encephalopathy, possibly due to alterations in calcium pumps. Animals may enter a so-called '''twitch-convulsive''' state where they suffer concurrent tremors, myoclonus and seizures. Peripheral neuropathies may contribute to the reduced hindlimb function that is commonly ascribed to hypokalaemic myopathy.