Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

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Chapter | 8 Porphyrins and the Porphyrias
phenylhydrazine poisoning, a type of porphyrinuria has
been observed that has some of the characteristics of erythropoietic
porphyria of humans and cattle ( Schwartz et al. ,
1952 ). A hepatic form can be produced with sedormid
(allylisopropylacetylcarbamide) ( Schmid and Schwartz,
1952 ), dihydrocollidine ( Granick and Urata, 1963 ), or
hexachlorobenzene.
B . Erythropoietic Porphyrias
1 . Bovine Congenital Erythropoietic Porphyria
a . Introduction
One of the characteristic findings in bovine congenital
erythropoietic porphyria (CEP) is a reddish brown discoloration
of the teeth and bones. Discolorations of this type
have been observed in cattle at slaughter since the turn of
the century, and these cattle are presumed to have had the
disease. The first living cases were encountered in South
Africa in a herd of grade Shorthorn cattle. Since then,
CEP has been reported in cattle in Denmark ( Jorgensen
and With, 1955 ), the United Kingdom ( Amoroso et al. ,
1957 ), the United States ( Rhode and Cornelius, 1958 ),
and Jamaica (Nestal, 1958). The disease has been seen
primarily in Holsteins with a few cases in Shorthorns and
Jamaican cattle.
The simple Mendelian autosomal recessive heredity of
the disease was established by the study of the genealogy
of the affected cattle and by breeding experiments. The
affected homozygotes are characterized by discoloration of
the teeth and urine, photosensitivity of the light areas of the
skin, and generalized lack of condition and weakness. The
condition is present at birth, and severely affected calves
must be protected from sunlight if a state of health is to be
maintained.
The predominant symptoms of teeth and urine discoloration
and the photosensitization of the severely affected
animal are readily apparent, and a tentative diagnosis can be
confirmed by the orange-red fluorescence of the teeth and
urine when examined with near ultraviolet light or a Woods
lamp. The symptomatology of affected animals, however,
may vary from minimal to severe and with age and season.
The discoloration of the teeth may vary in the same breed,
being more pronounced in the young and less apparent
in the older animals. Porphyrin deposits are heavily concentrated
in the dentine so the occlusal surfaces should
also be examined. If porphyrins are present, the discoloration
and the fluorescence of the dentine will be readily
detected.
The degree of photosensitization will vary with the
amount of porphyrin deposition in the dermis, coat color,
density of the coat, and extent of exposure to sunlight. The
photosensitization may be so slight as to escape detection.
At times, loss of condition may be the only outward symptom
for which the veterinarian is called. Marked variations
in the urinary excretion of the porphyrins also occur.
These may range from minimal to thousands of micrograms
in the same animal so that the urine color may vary
widely. The variations observed in this disease indicate the
dynamic state of flux of porphyrin metabolism in the living
animal, and the porphyrin deposits constitute a part of this
dynamic state.
b . Distribution of Porphyrins
Some normal values for the porphyrins in animals are
given in Table 8-4 . These values are to be considered as
best approximations obtained from a relatively few animals.
The figures, however, indicate the very low concentrations
of the free porphyrins normally found in the
body. Thus, the finding of porphyrins in greater than trace
amounts is always significant. Porphyrin concentrations in
porphyric cows and calves are given in Table 8-5 ( Kaneko
and Mills, 1970).
TABLE 8-4 Reference Values for Porphyrin Concentrations a
Urine ( k g/dl) Feces ( k g/g) RBC ( k g/dl cells) Plasma ( k g/dl) Bone Marrow
( k g/dl cells)
Species URO b COPRO COPRO PROTO COPRO PROTO COPRO PROTO URO COPRO PROTO
Cow 1.09 0.92 4.06 1.96 3.12 0.96 0.75 0.30 Trace Trace Trace Trace 1 5 100
0.80 1.60 2.05 6.15 1.11 4.28 0.15 1.25
Pig
c
104 118
Rabbit
c
25 41 25 c 2.6 83.3 Trace 4.5 87.5
Dog 50 c 50 c 35.0
a
References: Cow; Jorgensen (1961); Watson et al . (1959); Kaneko and Mills (1970). Pig: Cartwright and Wintrobe (1948). Rabbit: Schmid et al . (1952). Dog: Schwartz et al . (1960).
b
Abbreviations: URO uroporphyrin; COPRO, coproporphyrin; PROTO, protoporphyrin.
c
Micrograms per day.