Objective—To determine ultrasonographic abnormalities
in dogs with hyperammonemia.
Animals—90 client-owned dogs with hyperammonemia.
Procedure—Ultrasonography of the abdominal vessels
and organs was performed in a systematic way.
Dogs in which the ultrasonographic diagnosis was a
congenital portosystemic shunt were included only if
they underwent laparotomy or necropsy. Dogs in
which the abdominal vasculature appeared normal
and dogs in which the ultrasonographic diagnosis was
acquired portosystemic shunts and portal hypertension
were included only if liver biopsy specimens
were submitted for histologic examination.
Results—Ultrasonography excluded portosystemic
shunting in 11 dogs. Acquired portosystemic shunts
were found in 17 dogs, of which 3 had arterioportal
fistulae and 14 had other hepatic abnormalities.
Congenital portosystemic shunts were found in 61
dogs, of which 19 had intrahepatic shunts and 42 had
extrahepatic shunts. Intrahepatic shunts originated
from the left portal branch in 14 dogs and the right
portal branch in 5. Extrahepatic shunts originated
from the splenic vein, the right gastric vein, or both
and entered the caudal vena cava or the thorax.
Ultrasonography revealed splenic-caval shunts in 24
dogs, right gastric-caval shunts in 9 dogs, splenic-azygos
shunts in 8 dogs, and a right gastric-azygos shunt
in 1 dog.
Conclusions and Clinical Relevance—Results suggest
that ultrasonography is a reliable diagnostic
method to noninvasively characterize the underlying
disease in dogs with hyperammonemia. A dilated left
testicular or ovarian vein was a reliable indicator of
acquired portosystemic shunts. (J Am Vet Med Assoc
Objective—To determine size and weight of the pituitary
gland and associations between pituitary gland
size and weight and sex and age in horses without
clinical signs associated with pituitary pars intermedia
adenoma (PPIA) and horses and ponies with PPIA.
Animals—Pituitary glands from 100 horses without
clinical signs of PPIA and 19 horses and 17 ponies
Procedures—Pituitary glands were weighed, measured,
and examined histologically by use of H&E
stain. Masson trichrome and periodic acid-Schiff staining
were used, when appropriate. Histologic lesions
in the pars intermedia, pars distalis, or both were classified
as no significant lesions, single or multiple
cysts, focal or multifocal hyperplasia, single or multiple
microadenomas, and adenoma. Relative pituitary
weight (RPW) was calculated as pituitary weight
(grams) divided by body weight (grams).
Results—There was an age-related increase in the
presence of pituitary lesions in the pars distalis and
pars intermedia in geldings, mares overall, and nonpregnant
mares. Mean (± SD) RPW in horses with
PPIA was not significantly different from ponies with
PPIA (15 ± 5.9 X 10–6 and 16 ± 7.2 × 10–6, respectively).
Maximum pituitary weight in a horse with PPIA was
13.9 g (RPW, 2.9 × 10–5). Plasma glucose concentration
was positively correlated with RPW in ponies
Conclusions and Clinical Relevance—Pituitary
lesions may be a factor in horses with insulin resistance
and laminitis before development of clinical
signs of PPIA. Ovarian steroids may be involved in the
pathogenesis of lesions in the pars intermedia. (Am J
Vet Res 2004;65:1701–1707)