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Uroliths (Bladder Stones) Uroliths (bladder stones)“are abnormal mineral salt
concretions found in the urinary tract,” (Dennison et al. 2007 ; see also Berenyi
1972 ). Several factors including such as such as suboptimum temperatures, acute or
chronic infl ammatory conditions, dehydration, or purine-rich (animal protein) diets
seems to be responsible for their development. Of course, the phenomenon is species
dependent. Kidney stones in reptiles may be 100 % monosodium urate, or they may
be calcium oxalate (from feeding a diet high in plant foods containing oxalate), or
calcium phosphate (Kaplan 1997 ). The biochemistry of their formation is briefl y
described by Kaplan ( 1997 ) that monosodium urate is the form in which uric acid
usually presents in the blood. Both substances are largely insoluble in water.
The phenomenon of hyperuricemia develops when the serum concentration of
either free uric acid or urate salts is elevated. One of the characteristic marks of this
disease is so called tophi, the crystals which may circulate through the blood or
even the synovial fl uid. Finally, tophi can be observed in tissues, organs and joints
throughout the body. Crystals of monosodium urate affect gout, however the
pseudogout, another acute infl ammatory state, is caused by crystals other than
sodium urates (Kaplan 1997 ).
Of course, urine supersaturation with respect to uric acid can determine the
formation and development of uric acid uroliths. However, how this supersaturation
can occur? One of possible ways is related to urease-producing microorganisms,
which are responsible for corresponding infection. In this case, the mechanism can
be described as follow: “These bacteria split urea, leading to an increase in urinary
ammonia concentration and pH, which favors precipitation of struvite crystals,”
(Dennison et al. 2007 ). Relatively uncommon in marine mammals, uroliths are most
frequently reported in cats and dogs where they are generally in the form of struvite
and calcium oxalate (Dennison et al. 2007 ). However, two calculi were found in the
urogenital sinus of a 70 kg female sand tiger shark ( Odontaspis taurus ). The calculi
were white in color, rough on the surface, and spherical in shape. Crystallographic
examination revealed that they were composed of struvite (80 %) and calcium
phosphate (15 % carbonate apatite). Approximately 5 % of the stone matrix consisted
of blood and protein; a distinct bacterial nidus was not present microscopically
(Walsh and Murru 1987 ).
Reports concerning fi ndings of uroliths in marine mammals include urate
nephrolithiasis in a harbour seal ( Phoca vitulina ) (Stroud 1979 ; Greig et al. 2005 ) and
in a river otter ( Lontra canadensis ) (Grove et al. 2003 ); struvite penile urethrolithiasis
in a pygmy sperm whale ( Kogia breviceps ) (Harms et al. 2004 ); urinary calculus in
pygmy killer whale Feresa attenuate (Zerbini et al. 1997 ); two cases of calcium
carbonate nephrolithiasis in West Indian manatee ( Trichechus manatus ) (Moliner
2005 ; Keller et al. 2008 ); and urate calculi in bottlenose dolphins ( T. truncatus )
(Miller 1994 ; Venn-Watson et al. 2010a ; Schmitt and Sur 2012 ).
Uroliths of the uric acid origin have been previously reported in several species
of odontocetes. Usually, they have been located primarily in the ureter or kidneys of
these animals (Miller 1994 ; Reidarson and McBain 1994 ; Townsend and Ringway
1995 ; Boehm et al. 1997 ). Probably, the biggest struvite-based stone was observed in
3 Biocomposites and Mineralized Tissues
Uroliths (Bladder Stones) Uroliths (bladder stones)“are abnormal mineral salt
concretions found in the urinary tract,” (Dennison et al. 2007 ; see also Berenyi
1972 ). Several factors including such as such as suboptimum temperatures, acute or
chronic infl ammatory conditions, dehydration, or purine-rich (animal protein) diets
seems to be responsible for their development. Of course, the phenomenon is species
dependent. Kidney stones in reptiles may be 100 % monosodium urate, or they may
be calcium oxalate (from feeding a diet high in plant foods containing oxalate), or
calcium phosphate (Kaplan 1997 ). The biochemistry of their formation is briefl y
described by Kaplan ( 1997 ) that monosodium urate is the form in which uric acid
usually presents in the blood. Both substances are largely insoluble in water.
The phenomenon of hyperuricemia develops when the serum concentration of
either free uric acid or urate salts is elevated. One of the characteristic marks of this
disease is so called tophi, the crystals which may circulate through the blood or
even the synovial fl uid. Finally, tophi can be observed in tissues, organs and joints
throughout the body. Crystals of monosodium urate affect gout, however the
pseudogout, another acute infl ammatory state, is caused by crystals other than
sodium urates (Kaplan 1997 ).
Of course, urine supersaturation with respect to uric acid can determine the
formation and development of uric acid uroliths. However, how this supersaturation
can occur? One of possible ways is related to urease-producing microorganisms,
which are responsible for corresponding infection. In this case, the mechanism can
be described as follow: “These bacteria split urea, leading to an increase in urinary
ammonia concentration and pH, which favors precipitation of struvite crystals,”
(Dennison et al. 2007 ). Relatively uncommon in marine mammals, uroliths are most
frequently reported in cats and dogs where they are generally in the form of struvite
and calcium oxalate (Dennison et al. 2007 ). However, two calculi were found in the
urogenital sinus of a 70 kg female sand tiger shark ( Odontaspis taurus ). The calculi
were white in color, rough on the surface, and spherical in shape. Crystallographic
examination revealed that they were composed of struvite (80 %) and calcium
phosphate (15 % carbonate apatite). Approximately 5 % of the stone matrix consisted
of blood and protein; a distinct bacterial nidus was not present microscopically
(Walsh and Murru 1987 ).
Reports concerning fi ndings of uroliths in marine mammals include urate
nephrolithiasis in a harbour seal ( Phoca vitulina ) (Stroud 1979 ; Greig et al. 2005 ) and
in a river otter ( Lontra canadensis ) (Grove et al. 2003 ); struvite penile urethrolithiasis
in a pygmy sperm whale ( Kogia breviceps ) (Harms et al. 2004 ); urinary calculus in
pygmy killer whale Feresa attenuate (Zerbini et al. 1997 ); two cases of calcium
carbonate nephrolithiasis in West Indian manatee ( Trichechus manatus ) (Moliner
2005 ; Keller et al. 2008 ); and urate calculi in bottlenose dolphins ( T. truncatus )
(Miller 1994 ; Venn-Watson et al. 2010a ; Schmitt and Sur 2012 ).
Uroliths of the uric acid origin have been previously reported in several species
of odontocetes. Usually, they have been located primarily in the ureter or kidneys of
these animals (Miller 1994 ; Reidarson and McBain 1994 ; Townsend and Ringway
1995 ; Boehm et al. 1997 ). Probably, the biggest struvite-based stone was observed in
3 Biocomposites and Mineralized Tissues