Assessment of apoptosis in epidermal lamellar cells in clinically normal horses and those with laminitis

OBJECTIVE: To determine and compare the number, type, location, and distribution of apoptotic epidermal cells in the laminae of clinically normal horses and horses with laminitis. SAMPLE POPULATION: Formalin-fixed samples of digital lamellar tissue from 47 horses (including clinically normal horses [controls; n = 7], horses with acute [4] and chronic [7] naturally acquired laminitis, and horses with black walnut extract-induced [11] or carbohydrate overload-induced [18] laminitis). PROCEDURE: Blocks of paraffin-embedded lamellar tissues were stained for DNA fragmentation with the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) technique. Differential immunohistochemical staining for caspases 3 and 14 were used to confirm apoptosis. RESULTS: The number of TUNEL-positive epidermal cells per 0.1 mm of primary laminae was significantly greater in the acute laminitis group than in the other groups. In the acute laminitis group, there were 17 and 1,025 times as many TUNEL-positive basal layer cells and keratinocytes, respectively, compared with the control group. Apoptosis of TUNEL-positive basal layer cells was confirmed by results of caspase 3 immunohistochemical staining. The TUNEL-positive keratinocytes did not stain for caspases 3 or 14. CONCLUSIONS AND CLINICAL RELEVANCE: The large number of apoptotic basal layer cells detected in the lamellar tissue of horses with acute naturally acquired laminitis suggests that apoptosis may be important in the development of acute laminitis. The role of the large number of TUNEL-positive keratinocytes detected in the interface of primary and secondary epidermal laminae of horses with acute laminitis remains to be elucidated.     

Evaluation of a bladder tumor antigen test as a screening test for transitional cell carcinoma of the lower urinary tract in dogs

OBJECTIVE: To evaluate the veterinary version of the bladder tumor antigen (V-BTA) test as a screening test for transitional cell carcinoma (TCC) of the lower urinary tract of dogs. ANIMALS: 229 client-owned dogs. PROCEDURE: Urine samples from dogs were shipped overnight to a single laboratory to facilitate testing within 48 hours of collection by use of the V-BTA rapid latex agglutination urine dipstick test. Groups of dogs included the following: 1) dogs with TCC of the lower urinary tract, 2) healthy control dogs, 3) unhealthy control dogs with non-TCC urinary tract disease, and 4) unhealthy control dogs without urinary tract disease. Test sensitivity and specificity were calculated by use of standard methods. Logistic models were developed to assess the effect of disease status, test conditions, urine composition, and signalment on the performance of the V-BTA test. RESULTS: A total of 229 urine samples were analyzed, including 48 from dogs with suspected (n = 3) or confirmed (45) TCC. Test sensitivities were 88, 87, and 85% for all dogs with (suspected and confirmed) TCC, dogs with confirmed TCC at any site, and dogs with confirmed TCC of the urinary bladder, respectively. Test specificities were 84, 41, and 86% for healthy control dogs, unhealthy control dogs with non-TCC urinary tract disease, and unhealthy control dogs without urinary tract disease, respectively. The test performed slightly better on centrifuged urine samples than on uncentrifuged urine samples. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that the V-BTA test is useful in screening for urinary tract TCC in dogs.     

Comparison of 2 endothelin-receptor antagonists on in vitro responses of equine palmar digital arterial and venous rings to endothelin-1

The goals of this study were to determine the concentration-response (C-R) relationship of endothelin-1 (ET-1), compare 2 ET-receptor antagonists and determine the antagonist concentrations that block the vasomotor effects of ET-1, and compare the effectiveness of ET-1 and previously studied vasoconstrictors in equine palmar digital arterial and venous rings in vitro. Vessel rings from 8 nonlaminitic horses were placed in Tyrode's solution, 1 side fixed to the floor of an organ bath and the other side fixed to a force-displacement transducer. Two separate studies were conducted: (I) incubation with a single ET-receptor antagonist (PD142893 or PD145065 at a concentration of 10(-7), 10(-6), or 10(-5) M), followed by determination of an ET-1 C-R curve (using concentrations of 10(-10) to 10(-6) M) for medial vessel rings; and (II) comparison of ET-1 with norepinephrine and histamine (10(-10) to 10(-6) M) and comparison of contractile responses of medial and lateral vessel rings. In study I, ET-1 administration caused pronounced and sustained concentration-dependent contraction of vessel rings; these contractile responses were decreased by 10(-5) M PD142893 and were completely blocked by 10(-5) M PD145065. Venous rings had greater apparent maximum contraction in response to ET-1 than arterial rings. In study II, the relative sensitivity of norepinephrine was found to be equivalent to that of ET-1, whereas that of histamine was lower. No significant differences were observed between responses of medial versus lateral vessel rings. Thus, ET-1 is a potent vasoconstrictor of equine palmar digital arteries and veins, and the ET-receptor antagonist PD145065 is more effective than PD142893 in inhibiting these contractile effects in vitro.     

The immune response to dietary antigens and its influence on disease susceptibility in farm animals

Transient hypersensitivity reactions of the intestinal immune system to dietary antigens result in increases in enterocyte turnover and villous atrophy. These changes occur in the intestine of the post weaned piglet and precede the proliferation of E. coli and the development of post-weaning diarrhea. We therefore postulated that a transient cell mediated immune response to dietary antigens may increase susceptibility to disease. The interaction of dietary and microbial antigens upon the gut immune system has been investigated in mice and pigs and it has been shown that both exert powerful regulatory effects upon each other.