27 December 2015

Feline Idiopathic Cystitis (FIC)

One of the main reasons cats are taken to the vet is urinary tract issues, namely, the cat is using the litterbox frequently with little urine produced, or the cat is peeing outside of the box somethimes with blood.  These are the warning signs that the might have a bladder infection, bladder stones, bladder cancer, etc., or it may be suffering from feline idiopathic cystitis (FIC).

A note on acronyms:  In the early 1980s, this was usually termed FUS -- feline urological syndrome.  Thanks to an article in a 1984 journal, it became FLUTD -- feline lower urinary tract disease.  It has also been refered to as LUTS -- lower urinary tract signs and IC -- interstitial cystitis, which was borrowed from human medicine.  I will refer to it as the new preferred term -- FIC.

FIC strikes males and females equally, although males are by far more likely to become obstructed than females.  Risk factors seem to include stress, excess body weight, lack of activity, and multicat homes.

With humans, there are two types -- ulcerative and non-ulcerative.  With cats, almost all are non-ulcerative, and so, biopsies of the bladder are not recommended for cats suspected of having FIC.

The actual cause of FIC is unknown.  There seems to be no clear link between any virus and FIC.  There seems to be some connection with bacteria, namely cats with FIC are at increased risk of bacterial UTI.  The neurons assocaited with the bladder are larger and more sensitve in FIC cats than in normal cats.  Abnormalities in the hpothalamus, pituitary, and adrenal axis have been observed in cats with FIC.  Many cats with FIC also suffer from various other diseases leading researchers to wonder if FIC is a single disease or an expression of a larger disease process which effects other organs also.  One important "cause" is early kittenhood adversity, such as being orphaned or starved.

Diagnosing FIC is by exclusion of other diseases.  (The accompanying diagram shows most of the other possibilities.)  There is no clear diagnostic test, although researchers have found some biomarkers which seem to be linked to FIC.  Abdominal xrays are suggested since 20% with some type of urinary tract issue have crystals.

Treatment involves both drugs and environmental changes.  Narcotic pain-killers are recommended during a FIC period, whereas NSAIDs are not because of decreased blood flow to the kidneys.

The main treatment is modification of the cat's evironment to decrease stress.  An interesting question to help identify stress triggers is at http://indoorpet.osu.edu .  Increased water intake is seen as important, but using acidifying foods is not.  If the cat is fat, a safe diet needs to be undertaken.  Feliway may or may not be useful with FIC cats, but it was discussed and there is research on using it with these cats.  No drug, such as antidepressives, have been found useful.

Summarized from "Feline Idiopathic Cystitis", Jodi L. Westropp and C. A. Tony Buffington, pp.518-525 in Consultations in Feline Internal Medicine, v.7, 2015.

26 December 2015

Urinary Tract Infection in Cats

When a cat repeatedly visits the litter box, like 5 times in 10 minutes, or begins to pee outside the litter box, with even a drop or two of blood, one likely cause is a urinary tract infection.

There are several related medical problems that are related and must be clearly distinguished if treatment is to be successful.  They are:  bladder stones, urethral plugs in males, idiopathic cystitis, plus some other causes.  The key to determining IF it is a UTI is a urinalysis.  The urine specific gravity will help determine if the help distinguish upper urinary tract infection, associated diseases (e.g. CRF), or lower urinary tract infection.  A urine culture will determine the bacteria involved.  In more complicated cases, bloodwork, xrays, thyroid tests, and even an ultrasound may be needed.

The likey cause of most UTI's is bacteria spreading from the external opening up into the bladder and then even on to the kidenys.  Few infections seem to begin from blood into the kidneys, except in cases of trauma or urinary tract obstruction.  33-50% of all bacteria is E. coli.  25-33% are one of the many strains of Staph or Enterococci.  The remaining are a mix of 8+ bacteria.  In about 75% of the cases, only one bacteria is responsible for the infection, with 20% of the cases having 2 different species involved.  There is also the slim chance that a fungal infection can be the cause.

The standard treatment is antibiotics.  The first-line options are amoxicillin are trimethoprim-sulfadiazine.  Second-line option is nitrofurantoin.  Other antibiotics can be used, but many seem to be resistent to Enterococci.  Interestingly, the article says about clavamox "not established where there is any advantage over amoxicillin alone", which is intersting because clavamox is often seen as the go-to antibiotic.  Also of interest is the comment on cefovecin (Convenia) "Should only be used in situations where oral treatment is problematic" and it goes on to explain that the long duration interfers then with any post-treatment cultures for over 21 days.

In simple cases, treatment with antibiotics is for 10-14 days, with symptoms lessening in 48 hrs.  Sadly, simple UTI's are rare.  More complicated cases involving CKD or diabetes should be treated for 4-6 weeks.  Reinfection and relapse can occur.

The article also mentions alternative treatments, including cranberry extracts, D-mannose, methenamine hippurate, and probiotics.  Sadly there are no feline studies on any of these products.  Do note that methenamine is "poorly tolerated by feline patients".

Summarized from "Urinary Tract Infections", Shelly Olin and Joseph W. Bartges, pp 509-517, in Consultations in Feline Internal Medicine, v.7, 2015.

25 December 2015

Feline Uroliths

80% of all bladder stones (uroliths) in cats are either struvite or calcium oxalate. The remaining 20% are formed from a variety of minerals, each type occuring very rarely, and so I will focus on the two main types.
Struvite crystals form when the urine is not acid enough. These crystals come in two forms, sterile and infection-induced. The sterile form is just precipitated minerals from the urine. They are common in cats 1-8 yrs old, in both male and female. Diets low in magnesium, phosphate, and protein can lead to their dissolving. Prevention includes lowering the urine pH, decreasin urine specific gravity, and decreasing dietary magnesium, ammonium, and phosphates. Increased water consumption also helps prevent formation.
The infection-induced struvite crystals tend to form in very young or older cats. A bacterial infection in the bladder releases urease which then leads to the formation of the crystalline nidus (seed-crystal). The treatment of these crystals is much the same as sterile struvite crystals, except that antibiotics should be used while the dissolution food is being fed. The reason for this is the bacteria trapped in the stone are released as the stone is dissolved and can cause UTI or further stone formation. Antibiotics should continue for 2 weeks past when the stone no longer is visible on xrays or ultrasounds. Prevention of infection-induced struvite crystals does not require any change in diet -- only thorough treatment of any UTI.
Calcium oxalate crystals form when urine is too low in pH. Various medical conditions such as hypercalcemia is associated with an increase risk in calcium oxalate stones. These stones can not be dissolved by diet and must be physically removed. Prevention is treatment of any contributing medical condition and increasing fluid consumption.
In the photo, Photo A shows a typical sterile struvite crystal which is nicely round and smooth. Photo B shows 3 infection-induced struvite crystals -- note that they are smooth but geometrically shaped. Photo C shows a calcium oxalate crystal with typical spikes.
Based on "Update on feline Urolithiasis" by Amanda Callens and Joseph W. Bartges, pp. 499-508, in Consultations on Feline Internal Medicine, v7, 2015