Page 196 - Problem-Based Feline Medicine

188 PART 4 CAT WITH URINARY TRACT SIGNS

Cats with chronic renal failure may or may not have Bacteriology.
3
clinical signs, and pyuria and bacteriuria may not be ● Quantitative bacterial cultures ≥ 10 /ml of urine
obvious on examination of the urinary sediment. obtained by cystocentesis indicate urinary tract
infection.
Cats with urinary tract infection are rarely systemically
● Aerobic cultures and antimicrobial susceptibility
affected.
testing are indicated in cats with pyuria (>5
● Clinical signs of fever, lethargy, dehydration,
WBC/hpf) or elevated urine pH (>6.5) whether
anorexia, vomiting, polydipsia, polyuria, weight
or not bacteriuria is seen.
loss, anaemia are consistent with renal involve-
● Fungal cultures are indicated if blastospores (yeast)
ment and indicate ascending pyelonephritis.
or hyphae are seen in the urine.
Capillaria infestation is usually reported in cats over 8
Blood tests.
months of age and produces minimal clinical signs, but
● Leucocytosis and elevated serum urea and creati-
recurring bouts of hematuria and dysuria have been
nine levels indicate renal involvement in lower uri-
observed.
nary tract disease.
Encephalitozoon infestation may lead to renal failure.
Radiology.
● Plain and contrast radiography may help to identify
Diagnosis
some predisposing causes of urinary tract infec-
Urinalysis. tions, as well as, determine the chronicity of the
● If the urinary bladder is empty, cats can be given infection (thickened bladder wall, bladder fill
normal saline (70 ml/kg) subcutaneously, and blad- capacity).
der fill monitored. Alternatively, frusemide (1
mg/kg) intravenously can be used. Animals with Differential diagnosis
acute lower urinary tract infection are usually pollak-
iuric, so several attempts to collect urine may be nec- Non-obstructed idiopathic LUTD. Some cats diag-
essary throughout the day. nosed as having bacterial cystitis/urethritis often repre-
● Hematuria (>5 RBC/hpf), pyuria (>5 WBC/hpf) sent with a recurrence of lower urinary tract disease
and proteinuria (>3.5 g (35mg)/kg/day) or increased with sterile urine during or after appropriate antimicro-
protein/creatinine ratio >1.0 (N.B protein and creati- bial therapy. These cats have non-obstructed idiopathic
nine values must be converted to mg/dl and μmol/L, LUTD with secondary bacterial infection and can only
respectively to calculate the ratio) indicate inflam- be identified by reoccurrence of signs associated with
mation of the urinary tract. If bacteria are also seen sterile urine.
or cultured, then the inflammatory process is due to
or complicated by bacteria. If bacteria are not seen Treatment
under light microscopy, it does not mean that an
The principal objectives in the treatment of urinary
infection is not present as they, especially cocci, are
tract infection are to eliminate the infectious agent, cor-
not always readily visualized.
rect the predisposing cause, if possible, and prevent the
● White blood cell casts or granular casts indicate
recurrence of infection.
renal tubular involvement as in pyelonephritis.
White blood cell casts appear as tubular struc- Eliminate the infectious agent.
tures composed of white cells and Tamm–Horsfall ● For bacterial infections.
mucoprotein. These may degenerate and form – Antimicrobial drugs, selected on the bases of
granular casts, which are indistinguishable from bacterial sensitivity, should be used at appropri-
degenerated renal tubular epithelial casts. ate doses for 14 days for acute urinary tract
● Blastospores (yeast) or hyphae (Aspergillus spp.) in infection and for 28 days for chronic or recur-
urine indicate fungal infection. rent urinary tract infection.
● Capillaria ova (bipolar) or Encepalitozoon spores – Antimicrobial drugs often effective include
can be seen in the urine. Heavy infestations of sulfa-trimethoprim, enrofloxacin and amoxi-
C. feliscati may be associated with proteinuria. cillin with clavulinic acid.