VetInfo Digest       August 2004

 

Table of Contents:

Lower Urinary Tract Disorders:

 

cystitis/urethritis

incontinence

bladder stones

bladder cancer

blood in the urine for other reasons

 

OTC Medications We Use

 

This Month's Note:

Michal and I have once again had serious problems this month keeping up due to computer virus attacks. Completely different viruses managed to infect her work computer and the network at my office. This took several days to correct in both cases. It is awfully frustrating to have to spend time retrieving data and repairing damaged computers instead of answering questions from subscribers or organizing the information on the web site. We know that you don't have much influence over virus writers but if you ever do get the chance to discourage one from this kind of malicious mischief, please do!

Pfizer, the manufacturers of Revolution (Rx), used for heartworm prevention, flea control and a few other more minor problems, has written a letter to veterinarians stating that there may be some efficacy problems with Revolution when used for heartworm prevention. It is approximately 90% effective in the field based on their letter. This seems lower than the other heartworm prevention medications, although in all fairness I'm not sure their effectiveness has actually been studied. If you are using Revolution for heartworm prevention you might want to talk to your vet about this recent information.

 

The Urinary System

There are some disorders and body systems for which diagnosis and treatment are difficult, even for veterinarians. The urinary system, from the kidneys to the urethra, is one of these body systems. Well documented diagnostic and treatment information is either unknown or ignored by many veterinarians when treating urinary system disorders. There are some understandable reasons for this, including severely conflicting opinions among specialists in urinary disease as to most appropriate treatments or the best ways to reach a diagnosis for several disorders affecting the urinary system. I am not a specialist in any field and sometimes I do not feel qualified to discern who is correct when specialists disagree. However, I can read statistics and evaluate the design of research projects reasonably well, so it is possible to figure out some of the well proven diagnostic and therapeutic information. Please keep in mind that the information presented in this issue of the VetInfo Digest in regards to lower urinary tract disease is simply my best effort to sort out fact from fiction.

The most common lower urinary system disorders in both species are probably bladder inflammation or infections (cystitis), followed by chronic renal failure in cats and bladder stones in dogs. There are many other disorders that affect the urinary system, though. Making a concerted effort to reach a diagnosis, whenever possible, is worthwhile in urinary system disorders as many of these become chronic or recurrent illnesses.

Cystitis and Urethritis.

Cystitis is inflammation or infection of the urinary bladder. This is an important distinction, because infection must be treated with appropriate antibiotic or antifungal medications while inflammation will not respond to these medications. The probability of infection versus inflammation varies between dogs and cats and between males and females of both species, as well.

Urethritis is inflammation or infection of the urethra, the tube that carries urine from the urinary bladder to the end of the penis or the opening in the vagina. In male cats the urethra has a very small diameter at the penis and this can lead to urinary blockages at this site. It is possible to have urethritis without cystitis and visa versa but most of the time these conditions occur simultaneously, at least to some degree, so it is easiest to discuss them together.

A male cat with cystitis or urethritis has a very low probability of having infection as the cause of the condition. It is estimated that less than 1% of male cats who have urinary tract discomfort or blockage actually have an infection. Despite this, it is very common for these cats to be treated with antibiotics. There are a number of reasons for this but almost all of them have to do with the veterinarian's reaction to the client's perceived needs rather than to the disease process itself.

I think that a lot of veterinarians feel that if they don't dispense antibiotics and the problem turns out to be an infection, even though that is a rare event, they will be viewed as incompetent or sued by the client.

The other reason that veterinarians dispense antibiotics is that there isn't much else they can do for these cats. Antibiotics have become the placebo medication in veterinary medicine for urinary tract disease in male cats.

About half of male cats who have urinary tract inflammation have excessive crystal formation in the urine which leads to inflammation of the bladder or the urethra. There are several causes of this condition in cats but a major contributor is the relatively low water consumption and strong ability to concentrate urine in cats. Concentrated urine is just more prone to forming crystals. The most common type of crystal formed are referred to as struvite, MAP or triple phosphate crystals. These crystals dissolve in acid urine so most cats foods are now formulated to acidify urine. Dilution of the urine is also helpful so increasing the amount of moisture that the cat takes in its diet or by drinking water is helpful. The simplest way to increase water consumption is to switch from dry cat food to canned cat food or an appropriate home made diet.

It is important to point out that just having crystals in the urine, even a lot of crystals, does not guarantee that problems will occur or confirm that crystal formation is the problem if inflammation and crystals are present at the same time. In addition it is very important to understand that crystal formation occurs very quickly in urine after it is collected. In as short a time as a half hour there can be significant "after the fact" crystal formation which does not reflect the actual amount of crystal formation in the cat's bladder. When attempting to discern between inflammation from crystal formation, infection and other causes it is important whenever possible to obtain urine directly from the cat's bladder with a needle and syringe and to culture the urine for bacteria and then examine it immediately for crystal formation and other information it can provide.

Cystitis in female cats is more likely to be from infection, usually bacterial infection. The most common source of the bacteria is fecal contamination of the vaginal region of the female cat, making E. coli a common cause of infection. Even though infection is more common in female cats it still only causes about 20% of the cases of cystitis in female cats. Female cats also get crystal formation, just like male cats. The irritation from the crystals tends to produce signs of cystitis such as urinating frequently, urinating blood tinged urine, quitting the use of the litter pan or a general lethargy. These signs usually last a few days to a week or so and then clear up. They may repeat on a frequent basis, though.

Both male and female cats get a condition in which mucus formation and severe inflammation can occur in the bladder or urethra. In male cats this can lead to blockages that are referred to as mucus plugs. Whenever a male cat is blocked it is important to attempt to retrieve at least a small amount of the material causing the blockage so that it can be examined to determine if it is formed of crystals or mucus. The University of Minnesota has a long standing research project involving analyzing these blockages (and also bladder stones) for free. There is no known successful treatment for this condition and it does not usually respond to urinary acidification diets.

Cats sometimes develop a form of cystitis that is currently being referred to as chronic interstitial cystitis. This may be a severe form of the mucus forming cystitis/urethritis or it may be a separate entity. It affects female cats more often than male cats. It produces painful urination, often blood tinged, that lasts for a few days to a week or so and then goes away, with or without treatment. The underlying cause of this condition is not known with certainty but Dr. Osborne at the University of Minnesota is pretty convinced that this is a viral illness. There is no known treatment that works consistently and quickly to end the urinary tract discomfort. On the other hand, it does usually clear up on its own in a few a days and the time interval between attacks seems to lengthen as time goes on. This condition is not responsive to antibiotics but despite this most cats with it are treated with antibiotics. It is important to perform urine cultures on female cats with signs of cystitis whenever possible to try to differentiate between the possible causes of cystitis. This can be quite difficult to accomplish in practice, though. Cats with cystitis tend to urinate when even a small amount of urine collects in the bladder, due to the discomfort. This makes it very hard to find a time when it is easy to get urine from the bladder. Sometimes we have to keep cats in the clinic for the whole day just to be able to catch them at a time when there is enough urine in the bladder to do a good urinalysis and urine culture.

It is possible to culture urine that has been collected by "free catch", or in a cup or other container but the culture results are badly skewed by the presence of bacteria in the vagina and how quickly bacteria can multiply in urine. A negative culture in these circumstances is still useful but a positive culture is much harder to interpret There are corrective schemes, utilizing the numbers of bacterial colonies grown, that help to differentiate between bacterial growth from normal bacteria in the vagina or on the skin but these schemes are not as accurate as obtaining the urine by drawing it directly from the bladder. This is an easy procedure in cats. We can almost always get urine from the bladder if it is moderately full without anesthesia and in most cases without any protest from the cat.

Urinalysis is helpful in diagnosing cystitis. While the white blood cell indicator on many urine test strips doesn't work well for dog and cats the red blood cell indicators do. Having blood in the urine is very common when cystitis is present. High urine pH can help point towards a urinary tract infection, although alkaline urine can occur for other reasons.

If urine is not concentrated or has sugar in it, this should prompt a search for other diseases that can cause these changes. High protein levels in the urine sometimes occur when cystitis is present but this is also not a sure sign of infection since it can occur for other reasons. Even though the white blood cell portion of urine test strips doesn't work well, if white blood cells are seen on microscopic examination in any significant numbers this is a very reliable sign that infective cystitis is present.

Female dogs are prone to cystitis from bladder infection. This is even more likely if the female dog or cat is incontinent (can't control urination), has diabetes or has hyperadrenocorticism (Cushing's disease). Most cases of cystitis in female dogs involve bacterial infection but fungal infections are reported to be fairly common when female (or male) dogs have diabetes. It is reasonable to assume that cystitis in a female dog is infectious on the first visit and then to look for other causes if the problem recurs. While many vets are overcautious about prescribing antibiotics for cats with cystitis, veterinarians seem to be under cautious when it comes to prescribing antibiotics for cystitis in dogs. Most of the specialists who study cystitis think that it is best to give antibiotics for approximately 20 days on the first bout of cystitis, in the hopes of really clearing the problem up so that it doesn't become a chronic problem. It is best if the antibiotic is chosen based on a culture of the urine but it is a little harder to get a good culture sample from a dog -- not a lot harder, but just enough to put off veterinarians from attempting the cystocentesis (withdrawing urine with a needle and syringe) procedure.

When cystitis returns quickly after antibiotics are withdrawn in female dogs it is best to look for underlying causes for the infections pretty thoroughly. Blood work to rule out problems like diabetes and hyperadrenocorticism is a good idea, especially if there are other signs of these conditions such as increased drinking and urinating. X-rays to rule out bladder stones is also a good idea, especially when lab work is normal. A good physical exam to rule out inflammation around the vaginal folds, vaginal abnormalities and other anatomical defects that might make it easier for urine to pool or to back up into the bladder can help in ruling out underlying causes for the infections. If none of these conditions is found it may be that antibiotic choice was not appropriate or that antibiotics were not used long enough. It can take months to completely eliminate bacterial infection from the bladder in some female dogs. Checking for negative urine cultures at least three days after stopping the antibiotics is a good idea. Antibiotics should be resumed if bacterial growth occurs.

Male dogs with cystitis also have a higher tendency to have urinary infections than male cats. Male dogs also have a higher tendency to have prostate infections (prostatitis) than male cats. It can be a little difficult to differentiate between prostate infections and cystitis but some general guidelines can be helpful. Prostatitis is unusual in neutered males. If urine can be withdrawn from the bladder and it looks relatively normal while urine that is seen while the dog is urinating (or collected afterwards) looks like it has blood in it or is not clear then prostate infection in an intact male dog is more likely. In addition, the prostate gland tends to be enlarged when it is infected, which is often possible to determine by rectal palpation, X-rays or ultrasound examination.

When it seems clear that cystitis is the problem and not prostate infection in male dogs the procedures for treating the infection are similar to those in female dogs. In male dogs it is important to look for potential causes of urine retention, such as stones lodged in the urethra, and to rule out possible underlying diseases as these contribute more frequently to cystitis in male dogs since it is harder to contaminate the bladder with bacteria due to the location of the prepuce away from the rectum and its longer length. Male dogs do have a bone, the os penis, inside the penis near the end of the penis. This bone has a hard fixed diameter that is frequently smaller than the diameter of any stones that escape from the bladder, making it very important to check for stones in this location when male dogs are having difficulty urinating.

Urine culture and sensitivity testing is not a common procedure in veterinary medicine, despite the frequency with which cystitis occurs. When it is done, it is often done with urine collected "free catch" or with a catheter rather than being collected directly from the urinary bladder with a needle and syringe. This is one of the major downfalls in accurate diagnostic testing in veterinary medicine. Urine culture helps to ensure that antibiotics are not used inappropriately and can help to determine the underlying cause of cystitis. If urine cultures are negative it is important to look for something else.

Sensitivity testing is the process of determining what antibiotics will kill the bacteria that is cultured. It is sometimes expensive to do urine cultures depending on the laboratory charges and the difficulty in obtaining the urine. There is always some hesitancy to stick needles through the body wall and into the bladder, despite the knowledge that this almost never results in injury or infection but this fear is not justified compared to the benefits that result from the procedure. In our practice we are not aware of a single incidence of infection or traumatic damage to a urinary bladder or other internal organ after numerous cystocentesis procedures. If your dog or cat has recurrent bouts of cystitis it is very important to have urine culture done at some point in the diagnostic process.

There are some points it is critical to keep in mind about urine culture:

Before leaving the topic of urethritis and cystitis it is important to point out one final thing. Male dogs and cats who can not urinate can die within a very short period of time. This is true for female dogs and cats , too, but in the entire time I have been in practice I have seen one female dog with a urethral blockage not due to cancer and one female cat with a complete urinary blockage and this was due to cancer. If your dog or cat is trying to urinate but is not able to produce urine this is a true emergency situation. If your usual vet can not see you within an hour or two, go to another veterinary hospital. If your veterinarian refers emergencies to an emergency clinic go to the emergency clinic. This is not a time to wait for an appointment to see a more familiar veterinarian.

Incontinence

Incontinence is the inability to retain urine voluntarily so that urination times are controlled. This is easily confused with cystitis and frequently is confused with it. A careful review of when urination occurs usually makes it possible to differentiate between cystitis and incontinence but it is still better to run enough laboratory work to be relatively certain that incontinence is the problem. In addition, some diseases that increase the need to urinate can appear to be incontinence and these should be ruled out by lab work, as well.

Incontinence is common in spayed female dogs of any age and older intact female dogs. It is uncommon in cats of both sexes and male dogs. In most cases of incontinence urination will occur when the dog is laying down, sleeping or otherwise relaxed. Most dogs are not incontinent if they are active. The exception to this is incontinence due to nerve damage rather than hormonal changes. There is usually no blood in the urine. The dog often seems unaware that urination occurred.

Incontinence in female dogs will usually respond to treatment with estrogen compounds, usually diethylstilbestrol (DES) or to phenylpropanolamine (PPA). Most veterinarians start treatment with PPA as it is thought to have less potential for adverse side effects. If this is not successful the DES will usually help. If neither medication helps then it is necessary to consider causes other than hormonal imbalance as the cause of the incontinence. If you reach this point it is usually better to consider referral to a veterinary internal medicine specialist or even a veterinary neurologist because testing for nerve deficits, improperly positioned ureters and other uncommon causes of incontinence is not something the average practice does on a routine basis. If your vet is experienced at handling these problems there is no reason not to let him or her do so but don't hesitate to ask for referral to a specialist if things are going well.

Bladder Stones (Cystoliths, Uroliths)

Bladder stones are a fairly common cause of frequent urination, difficulty urinating and blood in the urine. The cause of bladder stones varies significantly between dogs and cats and even between breeds of dogs, so it is important to keep the species and breed in mind when bladder stones are found.

In cats MAP or struvite bladder stones form in sterile urine. These stones find it easiest to form in alkaline urine. This is another reason that urine acidifying diets are commonly used in cats. Unfortunately, the other common stone in cats, calcium oxalate bladder stones, like to form in acidic urine. Calcium oxalate bladder stones have become much more common in cats over the last ten years or so, which roughly correlates with the time that most cat foods went to the slightly acidic form. These stones also form most commonly in sterile urine. Infection may occur due to irritation from the stones breaking down the cat's normal immune system responses but these are usually secondary infections.

In dogs struvite bladder stones almost always occur in infected urine. This makes these stones more common in female dogs and also offers a way to avoid the stones -- keeping the urine from becoming or staying infected will prevent future stone formation. This does involve keeping a very close eye on urinary behavior and reporting any problems promptly to your veterinarian.

In both dogs and cats it is possible to dissolves struvite stones, in many instances, using specialized diets. The most common diet used for this purpose is s/d (tm) made by Hills. The diet doesn't always work but it works well enough to make it worth a try after the type of stone present has been identified. It is not a good idea to try the diet prior to stone analysis, since acidifying diets can make calcium oxalate stones more likely to form.

Other types of stones do occur in dogs and cats. Urate bladder stones are common in Dalmatians due to an inability to fully break down urates. Cholesterol stones can occur in dogs and stones of mixed origin (starting as calcium and ending up struvite or other combinations) also occur. It is important to have bladders stones analyzed after they are removed from the bladder to determine the type of stone that is present. This helps in crafting a plan to prevent recurrence of the stones, if that is possible. This is another service that the University of Minnesota Urology Lab offers for free (your vet may charge you for preparation and shipping of the specimen).

In many cases it is necessary to remove bladder stones surgically. In some cases it is possible to remove them using a procedure referred to as hydropropulsion, which consists of using water pressure to flush the stones from the bladder. This technique works pretty well in female dogs but is not as likely to help a male dog as there is a limit to the size of stones that fit through the bone in the penis. Hydropropulsion must be done under anesthesia so it is not risk free but it may be a better alternative for females with stones small enough to be passed through the urethra. It may not be necessary to remove all bladder stones. Sometimes a solitary stone forms or a small number of large stones form which are obviously not going to be passed but which do not appear to be causing problems, either. It is probably acceptable to monitor these types of stones without removing them if no signs of infection or discomfort are seen. Monitoring does have to be done carefully, though. If infection does develop over time it can become very severe since the stones give the bacteria a surface to grow on and a place to hide from antibiotics and natural defenses.

It can be very difficult to be certain that all bladder stones have been removed when attempting to remove them surgically. This is especially true in male dogs. It is important to try to ensure that no stones remain using postoperative or post hydropropulsion radiographs (for stones that show up on X-rays). Even this doesn't always eliminate the possibility of a stone remaining. We recently did surgery to remove bladder stones from a male dog and took X-rays after the surgery. We could not see any stones on the X-rays. Unfortunately, two stones were still present, because the dog could not urinate the next day and they were visible on X-rays at that time. We had to go back to surgery to remove the remaining stones. A male dog should be able to urinate with a nearly normal urine stream after bladder stones are removed. If he can't, you need to contact your vet as soon as possible.

Dogs and cats with diabetes and dogs with hyperadrenocorticism (Cushing's disease) need to be monitored very carefully for signs of cystitis as it occurs very frequently in patients with these diseases. In the case of diabetes cystitis due to fungal infection is not uncommon and has to be considered as a possible diagnosis, especially when antibiotics are not effective or are only partially effective in alleviating the signs of cystitis. About 40% of pets with diabetes will develop at least one case of cystitis and at least 25% of pets with Cushing's disease will have cystitis during the illness. In some dogs the only sign of Cushing's disease noted prior to diagnosis is chronic or intermittent cystitis. These disorders are more common in middle aged and older dogs and cats.

Bladder Cancer

Bladder cancer occurs in dogs more commonly than cats but it does occur in both species. It is most common in dogs over ten years of age. When cancer is present it is not uncommon for any signs of cystitis is causes, such as blood in the urine, to clear up if antibiotics are used. In most cases the signs reappear almost immediately after the antibiotics run out. If a diagnosis is not made and antibiotics are used repeatedly their effect will eventually be lessened.

It is often possible to diagnose bladder cancer by obtaining a urine sample and using a centrifuge to produce a sediment of cells and other heavier than water material that can be examined microscopically. Cells affected by cancer are fairly easy to recognize when transitional cell carcinomas, the most common type of bladder cancer, is present.

There often seems to be a higher level of discomfort when bladder cancer is present than when simple cystitis is present. Dogs often have subtle signs of a severe illness, such as gradual weight loss, reluctance to play or to participate in normal activities and in some cases lameness or weakness that doesn't seem to relate to orthopedic problems.

Blood in the Urine for reasons other than lower urinary tract disease

The presence of blood in the urine usually indicates that lower urinary tract disease is present. However, blood can be present in the urine if there is a bleeding disorder, in some forms of kidney damage, due to trauma, including trauma to the penis or vaginal regions.


In addition, there are some conditions in which the urine looks like it has blood in it but actually doesn't. Severe internal bleeding can lead to the presence of blood break down products in the urine that are red to purple in color even if whole blood isn't leaking into the urine. Heartworm disease in its end stages causes breakdown of the blood and produces urine that is often called "port wine" in color, sort of a deep purple-red color. Severe exertion or intolerance of exertion in some individuals can lead to breakdown of muscles and produce urine with a red to purple color, as well. When the signs seem to suggest something more than urinary tract disease it is a good idea to remember that blood can occur in the urine for a number of reasons and to look for other causes.

 

Over the Counter Medications That We Use

In the formulary lists for dogs and cats in the subscriber section of the web site (www.vetinfo.com/subscriber.html) there is a fairly complete list of medications that work well for pets, including most of the over the counter medications. Despite this, a number of subscribers have written to ask me which OTC medications I find useful. It occurred to me that it may be hard to determine from the formularies which medications can be purchased over the counter, so I am going to provide a list of some of them in this issue of the VetInfo Digest along with very brief indications for their use. The dosages are usually available in the formularies but it is always best to check with your vet before using any medication because even OTC medications can interact with other medications or be inappropriate for pets with certain conditions. Next month I'll try to cover some of the available herbal remedies and "nutriceuticals".

Aspirin -- this is one of my favorite medications. It is inexpensive, it works pretty well for arthritis pain and it is reasonably safe if used appropriately. It can cause gastrointestinal ulcers or discomfort. Use only with your vet's advice in cats!

Chlorpheniramine maleate (Chlortrimeton Rx): this antihistamine works well in some cats for itchiness or nasal congestion. Do not use combination cold remedies containing this and acetaminophen!

Clemastine (Tavist tm): antihistamine that helps alleviate itchiness in about 10 to 15% of dogs

Dextromethorphan - this is an ingredient in lots of cough medications and it works pretty well. It is important not to use a combination medication with acetaminophen (Tylenol tm) in it for cats.

Diphenhydramine (Benedryl tm): this antihistamine works well for about 10% of dogs with itchiness

Hydrocorticosone creams- these are useful in some dogs with allergic otitis or hot spots as a way of controlling itchiness. We like to put it on the inside of the ear flap of dogs with allergic ear inflammation.

Ivermectin (Ivomec 1% tm) - We use this medication for treatment of demodectic mange and sometimes sarcoptic mange. It is available as a cattle medication OTC and is sometimes much less expensive for clients to buy from agricultural supply stores. It is critical that you have your vet's advice on dosing!!

Ketoprofen (Orudis KT tm) -- this is a pretty potent non-steroidal anti-inflammatory medication that is useful for some dogs with occasional pain from arthritis or joint injury. Do not use it for more than a week.

Loperamide (Immodium AD)- this is useful in controlling diarrhea in pets.

Naphazoline (Clear Eyes Ophthalmic Drops tm)-- these are soothing for dogs with eye irritation from allergies, in some cases

Neomycin and Triple Antibiotic Ointments -- these first aid type creams are useful for minor injuries in pets as well as in people.


Pepto-Bismal (tm)-- Many people like this medication for minor stomach upsets. It has been reformulated to include salicylates so it should be used with caution, or not at all in cats. I included this one even though we don't really use it much. I like loperamide better for diarrhea.

Phenylephrine (Neosynephrine Rx) - the pediatric nasal drops are helpful in limiting congestion in small kittens and even older cats who have upper respiratory disease

Pyrantel Pomoate (many formulations): this is the dewormer that is safest for roundworms and hookworms. Try to look for this ingredient rather than just buying any deworming medication.

Tetracycline ophthalmic ointment (Terramycin tm)- this is an OTC eye ointment that is pretty safe to use and is very helpful for kittens and cats with gunky eyes.

Stridex Pads (tm) - These seem to help with canine and feline acne and Schnauzer comedone syndrome.

 

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The opinions expressed in this newsletter are those of Michael Richards, DVM., author.

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