Background
Obstructive urolithiasis is the most common condition of the urinary system in dogs. This may be due to infection, certain deficiencies and mineral imbalances. Sometimes the calculi get lodged at all the three positions i.e. kidney, urinary bladder and urethra and are difficult to manage. In such unusual cases radiographic and ultrasonographic observations are variable. The cystoliths and urethroliths may produce different image than the original during ultrasonography due to acoustic interface. Similarly the image of nephroliths can also be different. Present study was carried out to record these changes of appearance of nephroliths, cystoliths and urethroliths on radiograph as well as on ultra sonogram and how to manage such type of unusual cases of obstructive urolithiasis by medicinal and surgical methods.

1 Results and Discussion
The dogs started passing urine immediately after the surgery and all dogs made an uneventful recovery. The cases of obstructive urolithiasis are considered emergency cases in all domestic animals. In large animals diagnosis and evacuation of urine from the urinary bladder through rectum is comparatively easier as compared to small animals. In dogs and cats, radiography and ultrasonography are the only diagnostic methods in cases of obstructive urolithiasis (Kyles et al., 2005; Sharma et al., 2005). Radiography is being used to detect the presence of urethroliths and cystoliths for the last many years but now a day’s ultrasonography is also in use to detect the occurrence of urethroliths, cystoliths and nephroliths. The ultrasonographic appearance of shape of calculi is different from that of radiography. These observations were made in ten dogs. The shape of cystoliths in different dogs is variable and resemble to that of shape of eclipsed moon. The position of small calculi was sometime difficult to detect on ultrasonogram both in urinary bladder and urethra due to acoustic interface which is much easier to locate on radiograph. The ultrasonographic image of the os-penis is also observed to be different from that of radiograph. It can be depicted in form of thin lines on ultrasonogram. Most interesting feature of change in interface is observed in case of nephroliths. The nephroliths are much easier to be seen on ultrasonogram as compared to radiograph. Therefore the shape of calculus on ultrasonogram will depend on the density of surrounding tissue i.e. fluid or soft tissue. The change in urine density can also be seen by ultrasonography.

The treatment for presence of calculus in urinary system is carried out by both methods i.e. surgical and medicinal. The urethroliths and cystoliths are best managed by surgical methods (Kyles et al., 2005). In present study also it was observed that after surgical removal of calculus from urethra and urinary bladder the recovery of dogs was uneventful. The nephroliths can be managed by medical management also (Caraza, 2005) i.e. by using lithotripsy (Davidson et al., 2003), and dietary management (van Metre et al., 1996). In this study also the nephroliths were successfully managed by providing oral urinary antiseptics such as cystone. From this study it can be concluded that the use of fluid, antibiotics, analgesics, anti-inflammatory drugs, B-complex, oral urinary antiseptics i.e. cystone tablets after surgery were found to be useful for control of recurrence of lodgment of any calculus in urinary system. In dogs radiography is observed to be better diagnostic technique than sonography in cases of cystoliths and urethroliths. The sonography is comparatively better technique than radiography for nephroliths. The change of urine density in urinary bladder can be better observed by sonography.

2 Materials and Methods
Ten dogs, seven male and three female between age group of 5~7 years were admitted to the teaching veterinary hospital with the history of difficulty in urination. In these dogs, initially there was dribbling of blood tinged urination from the urethral orifice but in later stages either the urination was drop wise or there was complete stoppage of the urination. Several drugs such as diuretics, antibiotics, anti-inflammatory, B-complex and fluids were tried by the local veterinarians but there was no response. There was frequent vomition and constipation also. These dogs were dull, depressed and dehydrated. Polyethylene catheter was tried through urethra to take the urine out but it could not be passed. Immediately these dogs were referred for radiographic and ultrasonographic examinations. Blood was also collected and sent for laboratory examination. Hematology revealed mild anemia in these cases. There was increase in TLC, DLC and Packed Cell Values. Biochemical evaluation showed increase in values of Blood Urea Nitrogen, Serum Creatini¬ne, and SGOT and SGPT.

Radiographic reports indicated multiple cystoliths and urethroliths. In three male and two female dogs there was a single large sized calculus present in the center of the urinary bladder (Figure 1) while there was no calculus present in the urethra. In three other cases, there was unusual big calculus in the centre and many small calculi at the bottom of the urinary bladder. In these dogs almost entire urethral passage was occupied by the small calculi present in multiple rows (Figure 2).

Figure 1 Big cystolith

Figure 2 Multiple urethropliths

Ultrasonographic picture of the kidney, urinary bladder and urethra showed presence of cystoliths, urethroliths and nephroliths (Figure 3). The nephroliths could not be seen by radiography. A hyperechoic half moon shaped image of the cystolith was observed in the urinary bladder surrounded by the hypoechoic area. Density of the urine was appeared cloudy. The shape and size of cystoliths were observed to be changed due to acoustic interface (Figure 4). The urethroliths could not be seen clearly on ultrasonogram and the image of the os penis could be seen as a thin line (Figure 5).

Figure 3 Nephroliths

Figure 4 Cystoliths

Figure 5 Urethroliths

3 Surgical Management
Dogs were immediately prepared for aseptic surgery. Xylazine @ 1~2 mg/kg and ketamine @ 3~5 mg/kg were combined for induction as well as maintenance of anaesthesia. Skin was incised posterior to os-penis and urethra was opened to remove calculi. All the calculi could not be removed through this incision site. Urethrotomy was done at three different sites to remove rows of multiple calculi. These calculi are shown in the picture (Figure 6). A polyethylene catheter was passed from penile urethra to urinary bladder after clearance of urethra from calculi. Urethra, overlying muscles and skin were closed in routine manner.

Figure 6 Gross appearance of Urethroliths

To remove cystoliths, para-median cystotomy was done. The abdominal cavity was opened parallel to penis through para-median incision (Figure 7).

Figure 7 Paramedian cystotomy incision

Urinary bladder was taken out through this incision. Cystotomy was done to remove multiple calculi of different shapes and size. The shape of the calculi varies from oval, rectangular to round (Figure 8). The surface of these calculi was from smooth to granular. Cystorrhaphy was done to close the incision after removal of calculi. Peritoneum, muscles and skin were repaired in routine manner. Postoperatively, the dogs were administered full course of antibiotics, analgesics, anti-inflammatory drugs along with fluid and B-complex. Oral urinary antiseptic cystone was given for 20 days. Antiseptic dressing of the surgical wounds was followed up to 14 days daily till removal of the skin sutures.

Figure 8 Gross apprearance of Cystoliths

References
Caraza J.D.A., 2005, Medical management of the urinary retension, In 30^th world congress of the World Small Animal Veterinary Association held on May 11-14 at Mexico

Davidson E.B., Ritchey J.W., Higbee R.D., Lucroy M.D., and Bartels K.E., 2003, Laser lithotripsy for treatment of canine uroliths, Vet. Surg., 33(1): 56-61
http://dx.doi.org/10.1111/j.1532-950x.2004.04002.x

Kyles A.E., Hardie E.M., Wooden B.G., Adin C.A., Stone S.A., Gregory C.R., Mathews K.G., Cowgill L.D., Vaden S., Nyland T.G. and Ling G.V., 2005, Clinical, clinicopathologilogic, radiographic and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1982-2002), J. Am. Vet. Med. Assoc., 226(6): 932-936
http://dx.doi.org/10.2460/javma.2005.226.932 PMid:15786996

Sharma A.K., Mogha I.V., Singh,G.R., Amarpal and Aithal H.P., 2005, Haemato-biochemical changes in cases of obstructive urolithiasis in dogs, Indian J.Vet. Surg., 26(1): 65-66

van Metre D.C., House J.K., Smith B.P., George L.W., Angelos S.M., Angelos J.A. and Fecteau G., 1996, Obstructive urolithiasis in ruminants: Medical treatment and urethral surgery, Comp. Cont. Ed. Pract.Vet., 18(3): 317-328