ISRAEL JOURNAL OF
VETERINARY MEDICINE
TUBE CYSTOTOMY FOR TREATMENT OF URETHRAL CAL
OBSTRUCTION IN PET PIGS
Vol. 58 (4) 2003
O. Harari
Capital District Animal Emergency Clinic, Albany, NY and Kinderhook Animal Hospital a
Center, Kinderhook, NY.
Introduction
Miniature pigs have become popular household pets in the United States
in recent years, and present their owners and veterinarians with interesting
challenges.
Historically, domestic pigs have been treated by large animal veterinarians
clinics. The Vietnamese pot-bellied pigs are mostly household pets, and are
presented to the small animal practitioner by their owners who expect the
same standards of treatment that companion animals receive.
The urinary calculi syndrome (including urethral obstruction in males
accompanied by unsuccessful attempts to urinate and urinary bladder
rupture) occurs in miniature pigs. The incidence of cystic calculi may be the
same as in other pigs, but the frequency of urethral blockage is higher due to
the small urethral diameter, especially in barrows. (V. K. Chandna, personal
communication). The causes of the induction of urethral calculi and
obstruction are similar to those in the males of other species, and are
associated with early castration age, nutrition, urine pH, and bacterial cystitis.
Pigs presented for unsuccessful attempts to urinate pose both diagnostic
and therapeutic challenges. They may seem comfortable, will frequently
continue to eat, and may not become azotemic in the early stages of the
obstruction. In addition, it may be difficult to perform an abdominal palpation
to detect an unexpressible urinary bladder, and abdominal radiographs
usually show intestinal content superimposed on the bladder, and are
therefore difficult to interpret.
The pigs are often difficult to restrain because of their physique, strength,
and vocalization capabilities, and urinary catheterization of an
unanesthetized patient is very difficult because of the urethral anatomy.
Perineal urethrostomy has been performed for treatment of this syndrome
with partial success. Preventive and therapeutic measures to deal with
urethral obstruction in pet pigs have been given some attention, but no
thorough information is currently available. The literature describes surgical
procedures that may be beyond the scope of the general practitioner, without
the benefits of an academic or veterinary teaching hospital environment. (1).
The cases presented here were treated by tube cystotomy, a surgical
procedure well documented and widely used in small ruminants with urethral
obstruction. (2). The anesthesia protocol, surgical technique, and the post-
operative care vary slightly from that described for small ruminants, but
generally, the approach is essentially the same.
Case 1
A 7 month-old castrated male, pet pot-belly pig, weighing 14 Kg, was
presented for intermittent straining and poor appetite of two days duration.
The pig was admitted for physical examination and observation. It
exhibited a good appetite, a bright, alert, and responsive attitude, could
defecate normally but made unsuccessful attempts to urinate. The BUN was
5-15 mg/ml (AZOSTIX®, Bayer Corp., Elkhart, IN 46515, USA. Normal
range: 5-10 mg/ml), and abdominal palpation revealed an enlarged urinary
bladder. Cystocentesis resulted in collection of amber-colored urine. No
urinalysis was performed due to financial constraints.
Based on the history and findings, it was determined that the pig could be
experiencing lower urinary tract obstruction, and surgical intervention was
indicated.
Anesthesia: The pig was pre-anesthetized with Glycopyrrolate (RobinulV), 0.01 mg/ kg IM, followed by Telazol (Tiletamine HCL and Zolazepam
HCL), 2.28 mg/kg IM.
Once induced, anesthesia was maintained with Isoflurane at 1.5-2% and
oxygen via a mask. IV catheter (Abocath, 24g X 0.75 inch) was placed in the
right ear vein, and Lactated Ringers solution was administered at a rate of 60
ml/hr during the operation.
The pig was placed in dorsal recumbency, and the ventral abdomen and
right flank were surgically prepped.
Surgery: A right para-preputial incision was made to approach the caudal
abdominal structures. The urinary bladder was identified against the body
wall, and exteriorized carefully. The bladder was very large, full, firm, and
with a thin hemorrhagic wall. A small incision was made into the ventralapical bladder wall, and amber-colored, turbid urine was aspirated. The
bladder was irrigated with physiological saline solution and normograde
hydropulsation applied. Only a minimal flow of saline-urine was established
through the tip of the penis/preputial opening. The bladder wall was sutured
with 3-0 PDS.
A stab incision was made through the skin at the caudal right flank, and
the tip of a Foley balloon catheter (20 French) was introduced into the
subcutaneous space. The catheter was tunneled a short distance before
entering the abdominal cavity. An intact site at the right lateral bladder wall
was isolated, and the tip of the Foley catheter inserted into the bladder via a
puncture incision. The catheter balloon was inflated and the catheter was
secured in the bladder by a purse string suture (3-0 PDS) in the bladder wall.
At the skin exit site, mild traction was applied on the distal portion of the
catheter to position the urinary bladder closer to the body wall. The Foley
catheter was secured to the exit site with a purse string suture (2-0 Ethilon).
The abdominal muscular wall and peritoneum incision was closed with 2-0
PDS (single interrupted pattern), sub-cutaneous layer with 3-0 PDS
continuous pattern, and the skin with skin staples.
The Foley catheter was left open, and taped to the body dorsum.
Postoperati
ve care: IV fluid
flow was
maintained until
the pig was
ambulatory and
the IV catheter
lost patency.
Antibiotic
therapy was
initiated with
TrimethiprimSulfa (Primor),
22 mg/Kg PO, q
24 h, for 10
days.
Dietary
management
was aimed to
achieve urinary
acidification.
The pig ate
feline c/d
willingly. Two
Uroeze tablets
were crushed
and mixed in
Feline C/D (Hills
Pet Nutrition Inc.
Topeks, KS 66601,
U.S.A.) q 8 h.
The Foley
catheter was
remained open
for 4 days
postoperatively.
It was then
capped for
successive 2030 minutes
trials while urine
flow from the
preputial
opening was
monitored.
Fig 1: The pig in case 1, one day postoperatively
Normal urine stream from the preputial opening was observed 5 days
postoperatively. The catheter was then maintained capped for 24 hours. The
pig continued to urinate normally, the catheter was deflated and removed.
Follow-up: At time of suture and staple removal the pig was eating and
urinating normally. Recommendation was made to continue dietary
management to acidify the urine. (Lamb finisher pallets - Blue Seal, Feline or
Canine C/D supplements).
Three months after treatment, the pig was given to another owner and was
lost for follow-up.
Case 2
A 2 year-old castrated male pot-bellied pig, weighing 57 kg, was
presented for inability to urinate for one day. The only significant observation
on physical exam was stranguria.
Anesthesia: The pig was pre-anesthetized with glycopyrrolate (Robinul-V)
0.01mg/kg IM. Anesthesia was induced and maintained with isoflurane (1.54%) and oxygen via a mask.
The pig was placed in dorsal recumbency, and the ventral abdomen and right
flank were surgically prepped.
Surgery: The caudal abdomen was explored via a para-preputial incision.
The urinary bladder was distended but appeared healthy.
A tip of a Foley catheter was inserted first through the right flank skin,
tunneled subcutaneously, entered the abdomen and then into the urinary
bladder lumen through small stab incisions. The catheter balloon was inflated
and secured in the bladder lumen with a purse string suture (3-0 PDS) in the
bladder wall, and to the body wall with purse string suture (2-0 PDS), after
applying gentle traction on the distal catheter to position the urinary bladder
close to the body wall. Additional butterfly tape was sutured to the body wall
with 2-0 Ethilon, dorsal to the catheter exit site. The ventral abdominal
incision was closed with 2-0 PDS single interrupted pattern (muscle wall and
sub-cutaneous tissues) and surgical staples (skin).
The catheter was taped to the body wall, and remained open to allow urine
flow.
Laboratory: Urinalysis (urine sample collected during surgery) indicated
specific gravity of 1.020, pH 8.0, Protein: +100 mg/dl (normal, below 6) and
Blood: +250 Ery/µl (normal, below 5) (Chemstrip® 9). Urine sediment
demonstrated: rbc >100/hpf, wbc 2/hpf, bladder epithelial cells 0-2/hpf, triple
phosphate crystals 2-5/hpf and numerous bacterial rods.
Postoperative care: Antibiotic therapy was initiated with penicillin G
procaine 31,580 units/Kg IM. Furacin dressing was applied to the drain exit
site. Once fully recovered from anesthesia, dietary management for urinary
acidification was initiated with Uroeze tablets, 30 tablets daily, divided into
multiple feedings. Oral antibiotics therapy was continued with Primor
(Trimethiprim-Sulfa) tablets, 42 mg/kg, PO, q 24 h for the first day, then 21
mg/kg, PO, q 24 h, for 14 days.
Four days postoperatively the owner reported difficulty in administering the
medications. The pig began to vomit, showing discomfort associated with the
pelvic limbs, and no observed urine flow from the preputial opening. The
catheter was kept open, and was capped intermittently to allow assessment
of urethral urine flow.
Urinalysis indicated: S. G. of 1.016, pH of 8, Protein: trace, Blood:
50ery/µl, Urine sediment demonstrated: Bladder epithelial cells 2/hpf, rbc 2/hpf, wbc - 2/hpf, Calcium oxalate crystals 1/hpf, and numerous bacterial
rods and cocci.
Treatment protocol was modified as followed: Single injection of Azimycin
(Penicillin G Procaine in Dihydrostreptomycin sulfate solution with
Dexamethasone and Chlorpheniramine maleate) 0.09 ml/Kg IM. Oral
antibiotics were changed to Amoxicillin chewable tablets, 11 mg/Kg PO, q 12
h, for 10 days.
Bladder irrigation solution consisting of 200 ml physiological saline solution,
10 ml gentomycin sulfate 50 mg/ml, 5 ml dexamethasone 2 mg/ml, and 50 ml
of white vinegar was prepared. The owner was instructed to infuse 60 ml of
the solution into the bladder twice daily, and cap the Foley catheter opening
for 1-2 hours following the infusion.
Three days following initiation of the treatment, the owner reported the pig
was urinating normally.
Follow-up: Two weeks postoperatively the catheter and skin staples were
removed uneventfully. A telephone, call ten months after surgery revealed
that the pig was alive and well.
Discussion
The surgical procedure described in these cases presents the general
practitioner with the option of treating lower urinary tract obstruction in pet
pigs with a relatively conservative approach. Most alternative surgical
techniques (low urethrotomy without urethral closure, perineal urethrostomy,
and urethropreputial anastomosis) involve an invasive approach into the
urethra and are associated, unfortunately, with an increased risk of stricture
formation, urethral scarring, and predisposition for reobstruction.
The theory behind the tube cystotomy approach is that, by diverting urine
flow through the balloon-catheter, we allow bladder emptying until the urinary
bladder is capable of eliminating the urethral obstruction.
By minimizing the pressure in the bladder, the urethra is “at rest”, urethral
spasms are relieved, and the urethral calculi are allowed to pass. The use of
non-steroidal anti-inflammatory and anti-spasmodic drugs may assist in the
achievement of this therapeutic goal.
Urinary acidification and antibiotic therapy are believed to play a role in
dissolving the calculi by affecting their size and density. When needed and
possible, direct infusion of the bladder with an acidifying mixture through the
balloon catheter, seems to result in a rapid, positive response.
Special considerations in surgical procedures in pet pigs include: their drug
sensitivity; different responses to injectable anesthetic administration and
anesthetic doses due to thick subcutaneus fat, the high ulcerogenic potential
of drugs like banamine (Flunixin meglumine). The delicate nature of their
tissues during surgical handling; their laryngeal anatomy and high tendency
to develop laryngeal spasms, causing difficulties in endo-tracheal intubation,
and the risk of anesthesia-induced malignant hyperthermia.
Possible complications include failure of the Foley catheter to remain patent;
failure of the calculi to pass; destruction of the catheter due to chewing by a
second pig, causing premature deflating of the balloon and exit of the
catheter from the bladder; and urethral rupture.
LINKS TO OTHER ARTICLES IN THIS ISSUE
References
1. 1. Mann, F. A., Cowart, R. P., McClure, R. C. and Constantnescu, G.
M.: Permanent urinary diversion in two Vietnamese pot-bellied pigs by extra
pelvic urethral or urethropreputial anastomosis. JAVMA, 205(8); 1157-1160,
1994.
2. S. Fubini: Tube Cystotomy in Small Ruminants. In: Proceedings of the
104th Annual Meeting of NYSVMS, p.160, 1994.