Vet. Pathol. / 5: 676-6 78 ( 1978)
Hydronephrosis Caused by Urinary Lithia sis in a New Zea land White Rabbit ( Oryctolagus cuniculus) K. J . LEE, W . D. JOHNSON, C. M. LANG a nd R . D. HARTSHORN
Spo nta neo us hyd ron eph rosis in the rabbit has not been report ed , altho ugh the condi tion occurs in studies on terat ogeny [5, 6]. In rabb it urine crys tals composed of ammo nium magn esium ph osphat e (triple phosp hat e), ca lcium ca rbonate monoh ydrate, or anhy dro us ca lciu m car bo na te or all th ree [3] are foun d in relat ively large amou nts, but there has been no report of ur inar y calc uli. Crysta lline ma terial identified as car bonate apatite (a com ponent of urinary ca lculi in man [7]) occas iona lly has been seen in sectio ns of tissue from th e kidneys of norm al ra bbits [2]. Fo ur ad ult ma le New Zealand white ra bbits were used in a study to measure seru m q uinin e an d an tipy rine after phot oth erap y. All result s were withi n the ra nge of biologic var iability. Shor tly after the study was co mpleted, however, one of the rabbits ha d peri odi c ep isodes of anorexia and a grad ua l weig ht loss (from 5.2 to 3.2 kilograms with in 2 months). By palp ation the left kidn ey was judged to be abou t thr ee times the size of th e righ t one. The left ureter was pal pable. Serum crea tin ine was 5.4 mg/ l00 ml (no rma l range, 0.5 to 1.0 milligram). T he rabbit was killed an d autopsied . Macroscopi c lesion s were confined to th e urinary tract. T he left kidney weighed 87.25 grams . Th e dil at ed pelvis was filled with 30 milliliters of blood -t inged ur ine that con tained yellow gra nular mat er ial (fig. I). T he di stal thi rd of th e left ureter was occl uded by two round stones, having a com bined weight of 0.8 grams. Proxim al to this obs truc tion, the ur eter was dil ated to a diam eter of about I cen time ter. T he right kidn ey was no rmal in size and weighed 23.82 grams. T he cortex had a dep ressed circu lar ring, perpendicular to the long axis of the kidn ey, at the level of the hilus. Alt ho ugh the pelvis was no t en large d, it contained sma ll round calc uli (fig. 2). No stones were found in the right ureter. T he ca lcu li from the right kidney an d the left ure ter were composed primarily of phosp ha tes and ca lcium car bona te. Microscop ic exam ina tion of the left kidney showe d fibroplasia an d a loss of nephron s in the cortex; th e remai ning tubules were dilated . T he left ure ter was ulcera ted, and th e mucosa had been rep laced with fibrous con nective tissue. The righ t kidney had a few widely scattered areas of interstitial fibrosis. In the area of co rtica l de pression the nep h rons were rep laced by fibro us connective tissue, which had ca used the contraction of the capsu lar surface. In most species, urinary calcu li form in the pelvis of the kidney. In our rabbi t, two calculi beca me lodged in left ureter ; they obst ructe d the normal flow of urine and produ ced severe hyd ronephrosis . Little is known about the chem ical changes responsible for ur inary lith iasis. Herb ivores, unlike carnivores and omnivores, usu ally have an alka line ur ine (pH 8.0 to 9.0) beca use of the large amo unt of alka line carbonate in th e plant ash of their normal diet [I] . At a pH of 8.5 to 9.5, calci um ca rbonate an d ph osph at e crys ta ls ten d to precipitate from th e urine . Becau se ur ine was not co llected during th e drug me ta bolism study, we can not rul e out the possibility that the drug ca used an increase in the ur inar y pH. No urinary pro blem s, however, were seen in the other rab bits in the study; we have found sa bulous calcu li in the blad de rs of rabb its not used in stu dies on dru g meta bo lism . 676
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Brief Communication
677
Fig. I: U rina ry tract. Enlarged left kidney (L), 4.5 em d iam eter at hilu s, a nd left ure ter (a rrow). Right kidney normal in size but has depressed band (a rrow) oppos ite hilus. Fig. 2: Opened ur inary tra ct fro m figure 1. Enlarged left ren al pelvis and calculi in left ureter (wide arrow) and in pelv is of right kidn ey. Band in right kidn ey (na rrow arrow).
Downloaded from vet.sagepub.com at UNIV OF GEORGIA on June 5, 2015
67H
Br ie f Co m m u n icatio n
Althou gh the sta bility of supe rsat urated urine depends o n che mica l factors, most studies on urolithiasis have cente red o n the mech a nism s of stone forma tion rathe r th a n o n th e pre cipitating ca uses. These ca uses include infection, metabolic di sord ers, hormon al a nd nutritional imbalan ce, a nd inadeq uate wat er inta ke [4]. An y of th ese co ndi tio ns co uld ha ve been respon sibl e for sto ne for ma tion in th is ra bbit but a t th e tim e of death no ne see me d to be a primar y fac tor. References
2 3 4 5 6
7
BOYD, C .' A Te xtb ook of Path ology Structure a nd Function in Disease, pp. 943-994, 8th ed .; Lea & Fe biger, Phil ad elphia, 1970 FLATT, R. E.; CARPENTE R, A.B.: Identificati on of crys ta lline ma teri al in kid neys of ra bbits. Am J Vet Res 31:2247- 2250, 1970 FLATT, R.E.; CARPENTER, A.B.: Identificati on of crysta lline material in urin e of ra bbits. Am J Vet Res 32:655- 658, 1971 J unn , K .V.F .; KENNED Y, P.c.: Path ology of Dom estic A nima ls, pp . 322- 326, 2n d ed .; Academic Press, New York , 1970 MARKAM, J .K .; EMMERSON, J.L.; OWEN, N .V.: Terat ogeni cit y stud ies of methad on e HCl in ra ts a nd rabbits. Na ture (Londo n) 233:34 2-343, 1971 N OLEN, G.A.; BUEHLER, E.V.: The effects of di sodium etid ron at e re prod uc tive fu nc tion s a nd embryogenc y of albino rat s a nd N ew Ze aland rabbits. To xicol Appl Ph a rm acol 18:548- 561, 1971 PRIEN, E.L.; PRIEN, E.L., J r.: Co m pos ition a nd struc ture of urin ar y sto ne. Am J Med 45:654- 672, 1968
Requ est reprints from D r. Kap J . Lee, Depa rtment of Co m pa ra tive Medi cin e, Co llege of Medicine , T he Milt on S. He rsh ey Medi cal Center of T he Pennsylv ani a Stat e U nive rsity, Hershey, PA 17033 ( USA).
Downloaded from vet.sagepub.com at UNIV OF GEORGIA on June 5, 2015
Hydronephrosis Caused by Urinary Lithia sis in a New Zea land White Rabbit ( Oryctolagus cuniculus) K. J . LEE, W . D. JOHNSON, C. M. LANG a nd R . D. HARTSHORN
Spo nta neo us hyd ron eph rosis in the rabbit has not been report ed , altho ugh the condi tion occurs in studies on terat ogeny [5, 6]. In rabb it urine crys tals composed of ammo nium magn esium ph osphat e (triple phosp hat e), ca lcium ca rbonate monoh ydrate, or anhy dro us ca lciu m car bo na te or all th ree [3] are foun d in relat ively large amou nts, but there has been no report of ur inar y calc uli. Crysta lline ma terial identified as car bonate apatite (a com ponent of urinary ca lculi in man [7]) occas iona lly has been seen in sectio ns of tissue from th e kidneys of norm al ra bbits [2]. Fo ur ad ult ma le New Zealand white ra bbits were used in a study to measure seru m q uinin e an d an tipy rine after phot oth erap y. All result s were withi n the ra nge of biologic var iability. Shor tly after the study was co mpleted, however, one of the rabbits ha d peri odi c ep isodes of anorexia and a grad ua l weig ht loss (from 5.2 to 3.2 kilograms with in 2 months). By palp ation the left kidn ey was judged to be abou t thr ee times the size of th e righ t one. The left ureter was pal pable. Serum crea tin ine was 5.4 mg/ l00 ml (no rma l range, 0.5 to 1.0 milligram). T he rabbit was killed an d autopsied . Macroscopi c lesion s were confined to th e urinary tract. T he left kidney weighed 87.25 grams . Th e dil at ed pelvis was filled with 30 milliliters of blood -t inged ur ine that con tained yellow gra nular mat er ial (fig. I). T he di stal thi rd of th e left ureter was occl uded by two round stones, having a com bined weight of 0.8 grams. Proxim al to this obs truc tion, the ur eter was dil ated to a diam eter of about I cen time ter. T he right kidn ey was no rmal in size and weighed 23.82 grams. T he cortex had a dep ressed circu lar ring, perpendicular to the long axis of the kidn ey, at the level of the hilus. Alt ho ugh the pelvis was no t en large d, it contained sma ll round calc uli (fig. 2). No stones were found in the right ureter. T he ca lcu li from the right kidney an d the left ure ter were composed primarily of phosp ha tes and ca lcium car bona te. Microscop ic exam ina tion of the left kidney showe d fibroplasia an d a loss of nephron s in the cortex; th e remai ning tubules were dilated . T he left ure ter was ulcera ted, and th e mucosa had been rep laced with fibrous con nective tissue. The righ t kidney had a few widely scattered areas of interstitial fibrosis. In the area of co rtica l de pression the nep h rons were rep laced by fibro us connective tissue, which had ca used the contraction of the capsu lar surface. In most species, urinary calcu li form in the pelvis of the kidney. In our rabbi t, two calculi beca me lodged in left ureter ; they obst ructe d the normal flow of urine and produ ced severe hyd ronephrosis . Little is known about the chem ical changes responsible for ur inary lith iasis. Herb ivores, unlike carnivores and omnivores, usu ally have an alka line ur ine (pH 8.0 to 9.0) beca use of the large amo unt of alka line carbonate in th e plant ash of their normal diet [I] . At a pH of 8.5 to 9.5, calci um ca rbonate an d ph osph at e crys ta ls ten d to precipitate from th e urine . Becau se ur ine was not co llected during th e drug me ta bolism study, we can not rul e out the possibility that the drug ca used an increase in the ur inar y pH. No urinary pro blem s, however, were seen in the other rab bits in the study; we have found sa bulous calcu li in the blad de rs of rabb its not used in stu dies on dru g meta bo lism . 676
Downloaded from vet.sagepub.com at UNIV OF GEORGIA on June 5, 2015
Brief Communication
677
Fig. I: U rina ry tract. Enlarged left kidney (L), 4.5 em d iam eter at hilu s, a nd left ure ter (a rrow). Right kidney normal in size but has depressed band (a rrow) oppos ite hilus. Fig. 2: Opened ur inary tra ct fro m figure 1. Enlarged left ren al pelvis and calculi in left ureter (wide arrow) and in pelv is of right kidn ey. Band in right kidn ey (na rrow arrow).
Downloaded from vet.sagepub.com at UNIV OF GEORGIA on June 5, 2015
67H
Br ie f Co m m u n icatio n
Althou gh the sta bility of supe rsat urated urine depends o n che mica l factors, most studies on urolithiasis have cente red o n the mech a nism s of stone forma tion rathe r th a n o n th e pre cipitating ca uses. These ca uses include infection, metabolic di sord ers, hormon al a nd nutritional imbalan ce, a nd inadeq uate wat er inta ke [4]. An y of th ese co ndi tio ns co uld ha ve been respon sibl e for sto ne for ma tion in th is ra bbit but a t th e tim e of death no ne see me d to be a primar y fac tor. References
2 3 4 5 6
7
BOYD, C .' A Te xtb ook of Path ology Structure a nd Function in Disease, pp. 943-994, 8th ed .; Lea & Fe biger, Phil ad elphia, 1970 FLATT, R. E.; CARPENTE R, A.B.: Identificati on of crys ta lline ma teri al in kid neys of ra bbits. Am J Vet Res 31:2247- 2250, 1970 FLATT, R.E.; CARPENTER, A.B.: Identificati on of crysta lline material in urin e of ra bbits. Am J Vet Res 32:655- 658, 1971 J unn , K .V.F .; KENNED Y, P.c.: Path ology of Dom estic A nima ls, pp . 322- 326, 2n d ed .; Academic Press, New York , 1970 MARKAM, J .K .; EMMERSON, J.L.; OWEN, N .V.: Terat ogeni cit y stud ies of methad on e HCl in ra ts a nd rabbits. Na ture (Londo n) 233:34 2-343, 1971 N OLEN, G.A.; BUEHLER, E.V.: The effects of di sodium etid ron at e re prod uc tive fu nc tion s a nd embryogenc y of albino rat s a nd N ew Ze aland rabbits. To xicol Appl Ph a rm acol 18:548- 561, 1971 PRIEN, E.L.; PRIEN, E.L., J r.: Co m pos ition a nd struc ture of urin ar y sto ne. Am J Med 45:654- 672, 1968
Requ est reprints from D r. Kap J . Lee, Depa rtment of Co m pa ra tive Medi cin e, Co llege of Medicine , T he Milt on S. He rsh ey Medi cal Center of T he Pennsylv ani a Stat e U nive rsity, Hershey, PA 17033 ( USA).
Downloaded from vet.sagepub.com at UNIV OF GEORGIA on June 5, 2015
