In the present study, twelve male dogs ranging from 2-7 years of age with a mean age of 5.25±0.49 years comprising of 4 non-descripts, 2 pugs, 2 dalmatians, 2 spitz, 1 doberman cross and 1 shih-tzu were included. All the dogs were presented with clinical signs of urinary obstructions such as inappetance, depression, dysuria, stranguria and hematuria which are also in accordance with the case report presented by Rani et al., (2011).
Catheterisation was attempted with hydropropulsion using an appropriate sized urinary catheter for all the dogs in both the groups. After unsuccessful attempts of dislodging the urethral calculi decision was made to remove the calculi surgically with urethrotomy procedure.
There was no significant difference (P<0.05) in hematological values within and between the groups except in WBC counts.The reduction in WBC levels could be attributed to the reduced inflammatory changes at the urethra because of the low immunogenicity of collagen stent (Lin et al., 2006).
A significant difference was noticed in the BUN and creatinine values (P<0.01) within both the groups I and II between pre-operative and 14th
day of post-operative evaluation. In this study, the elevated BUN and creatinine values during pre-operative evaluation might be due to post-renal azotemia caused by obstructive urolithiasis which then gradually reduced to normal reference range after relieving the obstruction caused by the calculi through urethrotomy.
A significant difference (P<0.05) was observed in phosphorus values within the group I and a highly significant difference (P<0.01) in group II from pre-operative to 14th
day of post-operative evaluation.
Severity of renal damage would have resulted in a significant difference (P<0.01) in serum sodium and potassium values within both the groups I and II . A reduced renal function due to obstructive urolithiasis, disrupted the sodium-potassium homeostasis during pre-operative and 0 post-operative days.
There was no significant difference in the urethral diameter between and within the groups I and II on pre-operative and post-operative radiographic assessments which indicated that there was no urethral stricture formation post-operatively in both the groups (Table 1,2).
Table 1: Radiographic assessment of Group I.
Table 2: Radiographic assessment of Group II.
It could be inferred that use of collagen stent in urethra might have reduced the incidence of urethral stricture post-operatively after urethrotomy in dogs (Fig 6). This is in accordance with the findings of Jia et al., (2015).
Fig 6: Urethral lumen diameter radiographic assessment.
All the animals in both the groups I and II were confirmed with urethral calculi pre-operatively on ultrasonographic examination. In the present study, ultrasound was not only used to identify and locate the calculi but also to check the collapse, migration and absorption of the collagen stent placed inside the urethra by using different echogenicity between the urethral tissue and collagen matrix post-operatively on days 0, 3, 7 and 14 (Table 3).
Table 3: Mean±S.E. of pain score assessment of Group I and Group II (n=6).
In addition, Colour flow Doppler was used to check for urethral blood flow post-operatively. Stent collapse was noticed when an increased pressure was exerted on the ultrasound probe over the urethrotomy site while a gentle pressure negated the collapse of collagen stent. Absorption of collagen stent was identified by the absence of difference in echogenicity of the collagen matrix to the surrounding urethral and connective tissue. There was no stent absorption, migration or stent collapse on days 0 and 3 in all the animals in group II. However, there was a partial absorption of collagen stent observed in all the animals in group II on post-operative day 7. Complete absorption of collagen urethral stent was observed on day 14 in all the animals in group II. There was no stent migration or stent collapse observed on any of the post-operative day in all the animals in group II which could be attributed to the inclusion of the collagen matrix in the suturing of urethra which prevented the stent migration post-operatively which was similar in findings with Hill et al. (2014)
Bile salts and bile pigments were found in urine sample in 50% of the animals in group I and 33.33% of animals in group II pre-operatively. Blood was found in urine samples of 83.33% of animals in both groups I and II pre-operatively. Blood was also found in all the animals in both the groups I and II on the 7th day post-operative urinalysis and absent in all the animals in both the groups I and II on 14th
day post-operative urinalysis (Fig 7 and 8).
Fig 7: Urinalysis chart Group I.
Fig 8: Urinalysis chart Group II.
The presence of protein, bile salts and bile pigments in the urine pre-operatively could be attributed to the renal damage which compromised the glomerular filtration and tubular reabsorption which led to excess excretion of protein, bile salts and bile pigments. The presence of blood in urine in the pre-operative period could be due to the over distension of the urinary bladder, haemorrhage during cystocentesis or capillary damage at glomerular level. Presence of blood in urine on day 7 which might be due to the surgical procedures that receded on day 14 urinalysis upon bladder and urethral healing.
Subjective evaluation of the surgical wound
Subjective evaluation of the wounds from urethrotomy surgeries from group I and group II (Fig 9-14). There was no significant difference in the pain score between the groups I and II. However, a significant difference (P<0.01) was observed in pain score within the group I and group II. The pain was reduced to permissible levels in both the groups by day 14 of post-operative care (Table 4).
Table 4: Ultrasonographic assessment of urethrotomy of Group II.
Fig 9: Group I-urethrotomy-Post-operative evaluation of surgical wound on day 3.
Fig 10: Group I-urethrotomy-Post-operative evaluation of surgical wound on day 7.
Fig 11: Group I- urethrotomy-Post-operative evaluation of surgical wound on day 14.
Fig 12: Group II-urethrotomy-Post-operative evaluation of surgical wound on day 3.
Fig 13: Group II-urethrotomy-Post-operative evaluation of surgical wound on day 7.
Fig 14: Group II-urethrotomy-Post-operative evaluation of surgical wound on day 14.