Diseases of the Urinary System

By | June 23, 2010

Bladder Stones

Solids can appear in the urine for a variety of reasons and at locations from the kidney, down the ureter to the bladder; they may also form in the bladder and pass down the urethra to be voided as urination. They range from sandy (sabulous) material to large concretions of urinary calculi or stones and may become lodged at any point in the urinary system. Stones are apparent within the bladder itself; occasionally they remain in the kidney or in the urethra, particularly in males, and are then unable to pass beyond the os penis.

Solids in the urine usually grow around a tiny nucleus of material; eventually they become large single stones or a collection of smaller ones, causing local inflammation and some degree of obstruction, partial or complete. Further inflammation results, with discomfort or pain and more urinary stasis, which again increases the size of the solids. Dogs with bladder stones characteristically pass small, frequent amounts of urine as if unable to completely evacuate their bladders. There is often evidence of blood in the urine and there may be pain or obvious difficulties on urination. In small dogs, such as Miniature Dachshunds, or dogs as large as Corgis, it may be possible to feel calculi in the bladder, or to hear them rattle when gently moved.

Urinary calculi can sometimes be dispersed by dietary means, but veterinary help is always urgently needed. Surgical removal, although a major operation into the bladder or urethra, is not too difficult, but preventing a recurrence is often the most problematic aspect of post-operative treatment. Urinary tract infection must be eliminated, and every effort should he made to prevent solids from coming out of solution. Some calculi (phosphate) are more soluble in acid urine, others (oxalate and urate) in alkaline urine, and attempts to alter the acidity/alkalinity of the urine may be advisable, under veterinary guidance.

Another preventive measure consists in keeping the urine dilute. This can be’ achieved by feeding canned food wetter with the addition of water, possibly with added salt to stimulate thirst and increased water intake.

Calculi

Calculi are stones which result from solids coming out of solution in abnormal situations. Although calculi can occur in the gut, gall bladder, and salivary ducts, the most common sites are in the urinary system. Another common site for calculi is the urethra of male dogs as it passes through a channel in the os penis. A stone may become too large to pass through the restricted outlet, and surgical intervention becomes an emergency.

Cystitis

Inflammation of the bladder is usually the result of bacterial infection. The female urinary tract affords an easier entry for bacteria than in males, and cystitis is therefore more common in bitches. The effects of an inflamed bladder are frequent passing of small amounts of often blood stained, rather foul- smelling urine. Cystitis is almost always present when calculi form in the urinary tract, and the symptoms are similar. The animal may have difficulty in passing urine, usually because of pain. All cases of cystitis need urgent attention, particularly where there is urinary retention.

Other causes of cystitis are bladder tumours, which are relatively rare, and injuries following traffic accidents. In the latter case, blood is usually evident in the urine, but provided infection can be prevented and the injuries are not great. prospects of recovery are usually good. Radiography is needed to assess the extent of the damage. Techniques which introduce air into the bladder and the application of dyes to show the passage of urine through the urinary tract are widely used in the investigation of bladder disorders.

Treatment with antibiotics is lengthy and urine samples must be taken for several weeks.

Hematuria

Blood in the urine is usually the result of physical injury, urinary calculi or infectious disease. In bitches the blood passed during oestrus or otherwise arising from the womb needs to be distinguished from blood arising in the urinary system.

Hematuria accompanies some forms of poisoning; it can also be a manifestation of cystitis and not immediately obvious because blood in the urine is often broken down and merely seen as discoloration. Diagnostic tests are necessary to determine the cause of hematuria.

Harvest Mites

These parasites proliferate in certain localities in Britain. The larvae of Trombicula autumnale, the harvest mite, appear as small reddish-orange specks on the feet of dogs. just visible in good light, they cause severe irritation between the toes, their only indication being the dog’s continual attention to its feet by licking, chewing, and biting. Harvest mites are fairly easily controlled with careful use of medicated shampoos containing insecticidal agents. Only if secondary infection is introduced does other medical treatment become necessary.

Lice

Heavy infestation of these parasites shows as marked irritation, particularly around the head and neck; some types of lice live on blood and can cause anemia in young puppies. Lice are just visible, but more easily controlled than parasites, such as fleas, which spend part of their cycle away from the dog. Repeat applications of medicated shampoo are effective in most cases.

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