Age, segment, and horn disease affect expression of cytokines, growth factors, and receptors in the epidermis and dermis of the bovine claw.

The aim of this study was to examine changes in RNA expression for growth factors, cytokines, and receptors in epidermal-dermal tissues of the bovine claw relative to host age, claw segment, and disease state of the horn. Epidermal-dermal tissues were collected from the coronary, wall, sole, and bulb segments of 8- to 9-mo-old Holstein fetuses, normal adult cows, and adult cows with sole ulceration. Anatomic and pathologic characteristics were determined in tissues stained with eosin and hematoxylin, and RNA expression levels were evaluated using real-time, quantitative PCR. In normal tissues, certain RNA expression levels were clearly affected by host age: 290.0-, 610.0-, 53.4-, and 8.1-fold greater expression of granulocyte-macrophage colony stimulating factor was observed in fetal coronary, wall, sole, and bulb segment relative to adult tissues, respectively. A claw segment effect was also observed in that IL-1alpha expression was greater (1.59-fold) in the normal adult wall relative to the coronary segment, and IL-18 expression was greater (16.2-fold) in the normal adult sole compared with the coronary segment and 2.88 greater in the fetal sole relative to the bulb segment. Sole ulceration was associated with hemorrhage, thrombosis, inflammation, and striking increases in IL-1beta, IL-18, and inducible nitric oxide synthase, and with less dramatic, albeit measurable, changes in IL-1 type I receptor, IL-1 receptor antagonist, and tumor necrosis factor-alpha. Amidst striking increases in keratinocyte growth factor receptor (i.e., 21.0-fold, 10.4-fold, 0, and 21.6-fold in the coronary, wall, sole, and bulb segments, respectively), a concomitant decrease occurred in keratinocyte growth factor (i.e., 0.80-, 0.54-, 0.56-, and 0.72-fold, respectively). The results demonstrated changes in disease state and, to a lesser extent, claw segment and were accompanied by alterations in the RNA expression of several cytokines, growth factors, and receptors present in the normal claw.

Tissue predilection sites and effect of dose on Mycobacterium avium subs. paratuberculosis organism recovery in a short-term bovine experimental oral infection model.

The objective of this study was to develop a short-term experimental infection model for Mycobacterium avium subsp. paratuberculosis (MAP) in cattle, using small oral doses of organisms. Specifically, the effect of dose size was evaluated, as well as specific tissue predilection sites for recovery of MAP. Oral doses as low as 1.5 x 10(6) CFU reliably produced infection that could be detected 3 weeks following infection. Detection of infection required culture of multiple intestinal samples (jejunum and ileum) for MAP. Histological examination did not permit detection at this early stage. Results from this study suggest intestinal mucosa, rather than tonsil, as the primary portal of entry for MAP. The experimental infection model described here is useful for studying the early effects of preventive and therapeutic interventions for paratuberculosis in cattle.

Incidence of polysaccharide storage myopathy in draft horse-related breeds: a necropsy study of 37 horses and a mule.

Skeletal muscle samples from 38 draft horse-related animals 1-23 years of age were evaluated for evidence of aggregates of glycogen and complex polysaccharide characteristic of equine polysaccharide storage myopathy (EPSSM). Cardiac muscle from 12 of these horses was also examined. Antemortem serum levels of creatine kinase (CK) and aspartate aminotransferase (AST) from 9 horses with EPSSM and 5 horses without EPSSM were compared. Skeletal muscle from 17 horses contained inclusions of periodic acid-Schiff (PAS)-positive, amylase-resistant complex polysaccharide. Similar inclusions were also present in the cardiac muscle of 1 horse. A vacuolar myopathy with aggregates of PAS-positive, amylase-sensitive glycogen was seen in 8 other horses, and these findings are also considered diagnostic for EPSSM. Antemortem serum activities of CK and AST were often higher in EPSSM horses than in horses without EPSSM. Using the presence of amylase-resistant complex polysaccharide as the criterion for diagnosis of EPSSM, the incidence in this population was 45%. Inclusion of horses with aggregates of glycogen but no amylase-resistant complex polysaccharide as representative of the range of pathologic findings in horses with EPSSM resulted in a 66% incidence in this population.

Vertical migratory behavior of the infective third-stage larvae of Oesophagostomum dentatum.

The vertical migratory behavior of third-stage infective larvae (L3i) of Oesophagostomum dentatum was investigated using upright truncated agarose cones and equivalent conical depressions in agarose. Geotactic response varied with the age of the infective larvae. Four-day-old L3i showed no preference for the sloping surfaces of either indented or upright cones, while the 8-day-old L3i showed a positive geotactic reaction, migrating down the sloping surface of the depressions.

Effect of sodium bisulfate on skin and hooves of horses.

OBJECTIVE: To evaluate the safety of sodium bisulfate for use in horse barn environments by determining its irritant effect on skin and hooves. ANIMALS: 6 female mixed-breed ponies. PROCEDURE: Sodium bisulfate was applied to clipped intact skin of 6 ponies to evaluate its irritant effect after single (48 hours) and repetitive (6 h/d for 10 days) applications; similar areas of skin were used as untreated control sites. In addition, sodium bisulfate was applied to the sole of both front hooves of each pony and covered with wet gauze, and the entire hoof was covered with adhesive tape for 48 hours. RESULTS: Contact with moistened sodium bisulfate for 48 hours had no effect on pony skin. Contact with sodium bisulfate for 6 hours on 10 consecutive days did not cause gross changes but did cause mild to moderate microscopic changes including epidermal necrosis, hyperkeratosis, capillary congestion, edema, and diffuse mixed inflammatory cell infiltrate. All changes were limited to the epidermis and superficial dermis. Gross changes in hoof sole, signs of lameness, and increase in digital pulse pressure or pulse intensity were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Duration of contact with sodium bisulfate in this study was in excess of that expected under typical husbandry conditions. Despite this fact, gross changes in skin and hooves were not detected. Microscopic lesions were confined to the epidermis and superficial dermis. Results suggest that contact with sodium bisulfate under these conditions is safe.

Pulmonary aspergillosis in horses: 29 cases (1974-1997).

OBJECTIVE: To analyze medical records and identify factors that veterinarians can use to prevent pulmonary aspergillosis in horses or that would enable them to diagnose it as early as possible. DESIGN: Retrospective study. ANIMALS: 29 horses. PROCEDURE: Medical records were reviewed for horses with pulmonary aspergillosis diagnosed on the basis of characteristic postmortem findings. Information on history, clinical signs, disease progression, and postmortem findings was obtained. RESULTS: 25 of 29 (86.2%) horses had primary (n = 20) or secondary (5) disease compatible with loss of integrity of the gastrointestinal (GI) tract. The remaining 4 horses had a non-GI tract disorder; only 1 of these 4 had clinical signs associated with the respiratory tract (i.e., pleuropneumonia). Although 22 (75.9%) horses had various signs of respiratory tract disorders, an antemortem diagnosis of Aspergillus pneumonia was made in only 1 horse and was suspected in only 1 other. Fungal organisms were seen histologically in tissues other than the lung in 12 (41.4%) horses. CLINICAL IMPLICATIONS: Horses with enteritis, colitis, typhlitis, or other diseases of the GI tract that result in mucosal compromise, and horses with clinical signs of respiratory tract disease, particularly if the horse's condition is unresponsive to treatment with antimicrobial agents; should be considered at high risk of having pulmonary aspergillosis. Immunosuppression from debilitating disease may also predispose horses to aspergillosis. Because invasive pulmonary aspergillosis can be difficult to diagnose, clinicians should be aware of clinical and epidemiologic settings in which this disease would develop.

Hydrops amnii in a mare.

A multiparous pregnant Welsh Pony mare was examined because of anorexia, dyspnea, and a large abdomen. Ultrasonography of the uterus revealed an excessive amount of amniotic fluid surrounding the fetus. Transabdominal ultrasonography permitted differentiation of hydrops amnii from hydrops allantois. The mare aborted a 7-month-old fetus with brachygnathia and a large, edematous umbilical cord. Hydrops amnii, an excessive accumulation of amniotic fluid in the amniotic cavity, is most commonly reported in cattle and sheep.

Hepatic encephalopathy associated with paratuberculosis in a goat.

A 3-year-old pregnant Nubian goat that was examined because of weight loss, weakness, and change in attitude was determined to be infected with Mycobacterium paratuberculosis. Signs of depressed attitude, trembling, and ataxia were consistent with hepatic encephalopathy, which was confirmed by detection of hyperammonemia. These signs were consistent with histopathologic lesions in the liver and brain. Changes in energy balance and the hypoproteinemia that often develop in goats with paratuberculosis may lead to fat infiltration of the liver, hepatic insufficiency and, ultimately, hepatoencephalopathy.

Aortic root disease in four horses.

Clinical findings in 4 horses with aortic root disease are described. Three of the horses had aneurysms of the right aortic sinus, and in 2 of the 3, the aneurysm ruptured, creating a fistula between the aorta and right ventricle. One of these horses had had a murmur since birth, and the aortic sinus aneurysm may have been a congenital anomaly. In a second horse, the aneurysm may have been an acquired condition that developed secondary to chronic aortic regurgitation. Another horse had a large subendocardial hematoma associated with dissection of blood from the aorta to the interventricular septum because of a tear in the aortic root near the right aortic sinus. Ventricular ectopy and signs of abdominal pain were the most common initial signs in these horses.

Use of imipramine hydrochloride for treatment of urospermia in a stallion with a dysfunctional bladder.

An 8-year-old stallion was evaluated because of recurrent urinary tract infections and chronic intermittent urospermia. After extensive diagnostic testing, it was hypothesized that the stallion had a reflex dyssynergia of the bladder and urethral sphincter. Initial attempts to manage the urospermia included semen fractionation, semen collection after voluntary urination, and use of semen extenders. None of these efforts reliably yielded a quality ejaculate. Administration of imipramine hydrochloride (1.2 mg/kg of body weight, PO, 4 hours prior to semen collection) was initiated in an attempt to enhance bladder neck closure during ejaculation. This treatment, combined with voluntary urination prior to ejaculation, resulted in ejaculates containing little or no urine. Using this protocol, 19 of 20 mares bred during the subsequent 2 years became pregnant. By the third year, the bladder dysfunction had progressed, and the urospermia was no longer manageable. Bladder catheterization, followed by manual expression of the bladder per rectum, were necessary prior to each semen collection to obtain a urine-free ejaculate. Three-and-a-half years after initial examination, transitional cell carcinoma of the bladder with metastasis was identified, and the stallion was euthanatized. It is not known whether the transitional cell carcinoma was related to the dysfunctional bladder. Imipramine hydrochloride did not eliminate, but did reduce, the frequency and degree of urospermia in the affected stallion for approximately 2 years.

West Nile Flavivirus Polioencephalomyelitis in a harbor seal (Phoca vitulina).

A 12-year-old male harbor seal presented with progressive signs of neurologic dysfunction including head tremors, muzzle twitching, clonic spasms, and weakness. Lesions included polioencephalomyelitis with glial nodules, spheroids, neuronophagia, ring hemorrhages, and a few neutrophils. Neurons, fibers, and glial nodules were multifocally colonized with intracytoplasmic West Nile flavivirus antigens that were demonstrated using indirect immunohistochemical analysis. Flavivirus on cultured cells also was isolated and was identified by use of monoclonal antibodies and reverse transcriptase-polymerase chain reaction analysis. Clinical signs of disease and lesion morphology and distribution were similar to those of equine West Nile virus infection. Similar to horses, alpacas, humans, dogs, and reptiles, seals can be dead-end hosts of West Nile virus.

Myosin heavy chain composition in normal and atrophic equine laryngeal muscle.

The myosin heavy chain (MHC) composition of a given muscle determines the contractile properties and, therefore, the fiber type distribution of the muscle. MHC isoform expression in the laryngeal muscle is modulated by neural input and function, and it represents the cellular level changes that occur with denervation and reinnervation of skeletal muscle. The objective of this study was to evaluate the pattern of MHC isoform expression in laryngeal muscle harvested from normal cadavers and cadavers with naturally occurring left laryngeal hemiplegia secondary to recurrent laryngeal neuropathy. Left and right thyroarytenoideus (TA) and cricoarytenoideus dorsalis (CAD) were obtained from 7 horses affected with left-sided intrinsic laryngeal muscle atrophy and from 2 normal horses. Frozen sections were evaluated histologically for degree of atrophy and fiber type composition. MHC isoform expression was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of muscle protein. Histologic atrophy was seen in all atrophic muscles and some right-sided muscles of 3 affected horses, as well as the left TA of 1 normal horse. Fiber type grouping or loss of type I muscle fibers was observed in the left-sided laryngeal muscles in all but 1 affected horse, as well as in the right muscles of 2 affected horses, and the left TA of 1 normal horse. SDS-PAGE showed 2 bands corresponding to the type I and type IIB myosin isoforms in the CAD and TA of the 2 normal horses. Affected horses demonstrated a trend toward increased expression of the type IIB isoform and decreased expression of the type I isoform in atrophic muscles. This study confirmed the presence of histologic abnormalities in grossly normal equine laryngeal muscle, and it demonstrated an increased expression of type IIB MHC with a concurrent decreased expression of type I MHC in affected muscles. Evaluation of muscle fiber changes at the cellular level under denervated and reinnervated conditions may aid in assessing future strategies for reinnervation or regeneration of atrophic laryngeal muscle.

Morbilliviral dermatitis in seals.

A juvenile female hooded seal (Cystophora cristata) and a juvenile male harp seal (Phoca groenlandica) stranded separately on the New Jersey (USA) coast and were taken to a marine mammal rehabilitation center. Both were lethargic and emaciated, had dermatitis, and died. Histologic skin lesions in the seals were similar and consisted of epidermal and follicular epithelial hyperplasia, hyperkeratosis, degeneration, and necrosis. The most distinctive finding was extensive syncytial zones bounded superficially by hyperkeratosis and deeply by hyperplastic basal cells. Eosinophilic intracytoplasmic inclusion bodies were present in epithelial cells. Morbilliviral antigen was demonstrated in the skin lesions by immunohistochemistry. Phocine distemper virus was detected in the skin by reverse transcription polymerase chain reaction and a phocine distemper virus-specific probe using the Southern blot technique. This is the first report of morbilliviral dermatitis in marine mammals.

The pathology of spontaneous paratuberculosis in the North American bison (Bison bison).

Gross and histopathologic examinations were performed on 70 North American bison (Bison bison) from a Mycobacterium avium paratuberculosis culture-positive herd. The bison examined were part of a breeding herd totaling 2,800 animals. Eight of 70 (11%) animals had gross findings of intestinal mucosal thickening, and 16 of 70 (23%) of the animals had enlarged mesenteric lymph nodes. Histologic lesions compatible with Johne's disease were diagnosed in 30 of 70 (43%) bison on the basis of the demonstration of noncaseating granulomatous inflammatory infiltrates and of one or more acid-fast bacilli characteristic of Mycobacterium avium paratuberculosis. A suspicious diagnosis of Johne's disease was obtained in 11 of 70 (16%) bison on the basis of the observation of noncaseating granulomatous inflammatory infiltrates without demonstrable acid-fast bacteria. Twenty-nine of 70 (41%) animals were assessed as histologically paratuberculosis free. Histologic results were compared to Johne's disease tests such as culture, serology, and polymerase chain reaction, which were performed on some of the cohort animals.