Tissues Of Horses Research Articles

Histological evaluation of the equine larynx after unilateral laser‐assisted ventriculocordectomy

Trans-endoscopic laser surgery, such as unilateral laser-assisted ventriculocordectomy (LVC), has gained popularity in the treatment of RLN because a laryngotomy incision or general anaesthesia are not required. However, removal of the vocal fold and ventricle takes considerable laser energy and could cause collateral tissue damage, including injury to the adjacent laryngeal cartilages. To document the histological effects of laser surgery on laryngeal tissues in horses that have undergone LVC for the treatment of laryngeal hemiplegia (LH). Six horses were used: 4 with experimentally induced LH that had subsequently undergone LVC 6 months prior to euthanasia; and, 2 horses were used as controls. One of the control horses with naturally occurring LH was used to study the effect of neuropathy alone, whereas the other was subjected to euthanasia immediately following LVC to evaluate the acute effect of laser surgery. Using a band saw, each larynx was sectioned transversely at 5 mm intervals and evaluated histologically. Acutely, LVC caused thermal damage to adjacent soft tissues but did not affect the histology of the laryngeal cartilages. Six months after LVC, laryngeal cartilages were histologically normal and there was squamous metaplasia of the repaired laryngeal mucosa, resulting in restitution of the mucosal integrity. Using a diode laser in contact fashion at 20 W, LVC can be used to remove the laryngeal vocal fold and ventricle without causing laryngeal cartilage damage. Laryngeal chondritis is an unlikely consequence of LVC.

Expression of cyclooxygenase-1 and -2 in naturally occurring squamous cell carcinomas in horses

To assess expression of cyclooxygenase (COX)-1 and -2 in naturally occurring squamous cell carcinomas (SCCs) and the analogous normal tissues in horses. Tissue samples collected from 3 conjunctival, 2 vulvar, 4 preputial, and 5 penile SCCs during surgical excision in 14 horses and from corresponding body regions (conjunctiva [n = 5 horses], vulva [2], prepuce [3], and penis [3]) in 5 horses euthanized for reasons unrelated to neoplasia. Tissue samples were snap frozen in liquid nitrogen and stored at -80 degrees C until analysis. Protein was extracted from the frozen tissues, and western blot analyses were performed. Nonneoplastic and abnormal tissues from each body region were run on the same blot, and blots were run in triplicate. Molecular-weight markers and COX-1 and 2 ovine standards (positive control samples) were run concurrently on the gels; negative control samples were not used. All tissues, including the nonneoplastic and SCC tissues, expressed both COX-1 and -2 proteins. Results indicated that the expression of COX proteins in both nonneoplastic and SCC-affected tissues in horses is markedly different from that in other species. The reason for the potential benefit of COX-2 inhibitors in horses and other species is unknown. Further research needs to be performed to evaluate the efficacy of COX-2 inhibitors as cancer treatments in horses. Investigation of the mechanisms of tumor development in horses should be performed to increase understanding of this disease and ascertain how the mechanisms differ from those in other animals.

Neutrophil myeloperoxidase measurements in plasma, laminar tissue, and skin of horses given black walnut extract

To compare measurements of myeloperoxidase (MPO) in plasma, laminar tissues, and skin obtained from control horses and horses given black walnut heartwood extract (BWHE). 22 healthy 5- to 15-year-old horses. Horses were randomly assigned to 4 groups as follows: a control group given water (n = 5) and 3 experimental groups given BWHE (17) via nasogastric intubation. Experimental groups consisted of 5, 6, and 6 horses that received BWHE and were euthanatized at 1.5, 3, and 12 hours after intubation, respectively. Control horses were euthanatized at 12 hours after intubation. Plasma samples were obtained hourly for all horses. Laminar tissue and skin from the middle region of the neck were harvested at the time of euthanasia. Plasma and tissue MPO concentrations were determined via an ELISA; tissue MPO activity was measured by use of specific immunologic extraction followed by enzymatic detection. Tissues and plasma of horses receiving BWHE contained significantly higher concentrations of MPO beginning at hour 3. Laminar tissue and skin from horses in experimental groups contained significantly higher MPO activity than tissues from control horses. Concentrations and activities of MPO in skin and laminar tissues were similar over time. In horses, BWHE administration causes increases in MPO concentration and activity in laminar tissue and skin and the time of increased MPO concentration correlates with emigration of WBCs from the vasculature. These findings support the hypothesis that activation of peripheral WBCs is an early step in the pathogenesis of acute laminitis.

Novel findings regarding Glut-4 expression in adipose tissue and muscle in horses – A preliminary report

One of the hallmarks of insulin resistance is a reduction in glucose transporter-4 (Glut-4) expression in adipose tissue but not in skeletal muscle. However, while Glut-4 has been demonstrated in skeletal and cardiac muscles in horses it has not been demonstrated in adipose tissue. The initial objectives of the present study were: (1) to test the hypothesis that Glut-4 expression would vary between selected key skeletal muscles; (2) to test the hypothesis that it would also vary between representative adipose tissue depots, and (3) to see whether expression would be greater in adipose tissue compared to muscle. Glut-4 expression was determined by Western blot using samples obtained from post mortem biopsies obtained from four muscles (gluteus medius, semitendinosus, heart, and diaphragm), and four adipose tissues (subcutaneous, retroperitoneal, mesenteric, and omental) in three horses. There were no differences (P>0.05) in Glut-4 protein expression between the muscles sampled. Likewise there were no differences (P>0.05) in Glut-4 protein expression between fat depots. There was a significant difference (P=0.03) when pooled means for Glut-4 expression in muscle (58.8±2.5 densitometry units) were compared with adipose tissue (115.8±15.7). This difference in Glut-4 expression in these two tissues with distinctly different metabolic reasons for taking up glucose may warrant further investigation to see if there are more pronounced differences in Glut-4 expression in muscle and adipose tissue in various populations of horses.

Detection of equine herpesvirus-specific effector and memory cytotoxic immunity in the equine upper respiratory tract

Immunological protection of horses from equine herpesvirus-1 (EHV-1) infection and disease depends on the cooperation of virus-specific humoral and cellular immune responses. EHV-specific mucosal immunity may be an important component of such immune responses. This study demonstrates the induction of anti-EHV cytotoxic cellular immune responses in various mucosal and systemic lymphoid tissues associated with the upper respiratory tract (URT) of the horse. Four young horses (1–2 years of age) were inoculated intranasally with the Army 183 strain of EHV-1 and euthanized 1 week later. One untreated foal served as a non-infected control. Mucosa-associated tonsillar tissues, draining lymph nodes and PBMC were harvested. Virus-specific memory and effector cytolytic activity were individually assessed using 4 h chromium release assays, with and without in vitro restimulation with EHV-1, respectively. EHV-specific cytotoxic activity was detected ex vivo in several URT-associated mucosal lymphoid tissues of horses, particularly within the lining of the nasopharynx, a principal site of EHV-1 replication. This activity was also detected in the circulation of some horses 1 week post-challenge. Virus-specific memory cytotoxic activity was elevated in the circulation, and detectable in the draining lymph nodes of all horses following challenge infection.

Detection of the reemerging agent Burkholderia mallei in a recent outbreak of glanders in the United Arab Emirates by a newly developed fliP-based polymerase chain reaction assay

A polymerase chain reaction (PCR) assay targeting the flagellin P ( fliP)-I S 407A genomic region of Burkholderia mallei was developed for the specific detection of this organism in pure cultures and clinical samples from a recent outbreak of equine glanders. Primers deduced from the known fliP-IS 407A sequence of B. mallei American Type Culture Collection (ATCC) 23344 T allowed the specific amplification of a 989-bp fragment from each of the 20 B. mallei strains investigated, whereas other closely related organisms tested negative. The detection limit of the assay was 10 fg for purified DNA of B. mallei ATCC 23344 T. B. mallei DNA was also amplified from various tissues of horses with a generalized B. mallei infection. The developed PCR assay can be used as a simple and rapid tool for the specific and sensitive detection of B. mallei in clinical samples.

Determination of glutathione peroxidase and superoxide dismutase-like activities in equine spermatozoa, seminal plasma, and reproductive tissues

To determine glutathione peroxidase (GPX) and superoxide dismutase (SOD)-like activities in spermatozoa, seminal plasma, and reproductive tissues (ie, testis, epididymis, bulbourethral gland, prostate, vesicular gland, and ampulla) in horses. Seminal plasma from 17 stallions, spermatozoa from 5 stallions, and reproductive tissues from 3 stallions. Activity of GPX was determined by use of assays measuring oxidation of NADPH in the presence of exogenous glutathione, cumene hydroperoxide, and glutathione reductase. Activity of SOD-like enzymes was determined by use of the nitroblue tetrazolium assay. Mean GPX and SOD-like activities in seminal plasma were 1.3 +/- 0.1 nmol of NADPH oxidized/min/mg of protein and 29.2 +/- 6.6 U/mg of protein, respectively. Mean GPX activities in spermatozoa separated from seminal plasma by centrifugation and via Percoll gradient were 2.2 +/- 0.3 nmol and 6.1 +/- 1.3 nmol of NADPH oxidized/min/mg of protein, respectively. Mean SOD-like activity of spermatozoa separated by centrifugation was 58.6 +/- 22.3 U/mg of protein; SOD-like activity was not detected in Percoll-separated spermatozoa. Among reproductive tissues, the ampulla and prostate had the highest SOD-like activity, although this was not significantly different from activity in other tissues. Testes and spermatozoa from the cauda epididymis contained significantly more GPX activity than other tissues. Results suggest that although equine seminal plasma contains high SOD-like enzyme activity, spermatozoa have limited GPX and SOD-like activity. Enzymatic antioxidant activity in equine spermatozoa appears to be predominantly derived from seminal plasma adsorbed onto the plasma membrane. Removal of seminal plasma during semen processing may increase oxidative stress in equine-spermatozoa.

Infection of Immunodeficient Horses withSarcocystis neuronaDoes Not Result in Neurologic Disease

Equine protozoal myeloencephalitis is a progressive neurologic disease of horses most commonly caused by infection with the apicomplexan parasite Sarcocystis neurona. Factors affecting neuroinvasion and neurovirulence have not been determined. We investigated the pathogenesis of infection with S. neurona in horses with severe combined immune deficiency (SCID). Two immunocompetent (IC) Arabian horses and two Arabian horses with SCID were infected orally with 5 x 10(5) sporocysts of S. neurona. Four IC horses and one SCID horse were infected intravenously (i.v.) with 5 x 10(8) merozoites of the WSU-1 isolate of S. neurona. Despite prolonged parasitemia and persistent infection of visceral tissues (skeletal muscle, cardiac muscle, lung, liver, and spleen) as demonstrated by PCR and culture, SCID horses did not develop neurologic signs after oral or i.v. infection. S. neurona was undetectable in the neuronal tissues of SCID horses by either PCR, immunohistochemistry, or culture. In contrast, although parasitemia was undetectable in orally infected IC horses and of only short duration in i.v. infected IC horses, four of six IC horses developed neurologic signs. S. neurona was detectable by PCR and/or culture of neural tissue but not visceral tissue of IC horses with neurologic disease. Infected SCID horses are unable to clear S. neurona from visceral tissues, but the infection does not result in neurologic signs; in contrast, IC horses rapidly control parasitemia and infection of visceral tissues but frequently experience neuroinvasion and exhibit clinical signs of neurologic disease.

Detection of West Nile virus using formalin fixed paraffin embedded tissues in crows and horses: quantification of viral transcripts by real-time RT-PCR

Detection of West Nile virus using formalin fixed paraffin embedded tissues in crows and horses: quantification of viral transcripts by real-time RT-PCR

Quantitative measurement of essential and not essential metals in muscular, hepatic and renal tissue of horses by means of PIXE technique

Nowadays, the food safety and the related health risks for humans are a major issue. It has become a priority to ensure the health and well-being of the population through the better scientific understanding of the food intake influence. A frequently found harmful feature of human diet is the simultaneous presence in food stuff of both essential and toxic elements. A significant example of this situation is represented by horse meat. The aim of this survey is to evaluate the elemental content of muscular, hepatic and renal tissues of horses bred in different countries of the East of Europe and slaughtered in Italy. The studied population consisted of about 100 individuals; the sampling period, coinciding with the highest market request, was extended from November to March. Freeze dried tissues were pelletized and carbon coated prior to analysis. The samples were analyzed using Particle Induced X-ray Emission (PIXE) technique at the AN2000 van de Graaff accelerator of the INFN-National Laboratories of Legnaro. The accuracy of the results was verified using certified standard reference materials prepared and measured in the same experimental conditions. Results have highlighted the noble nutritional values of horse muscular tissue in terms of iron, zinc and calcium content. Cadmium was staidly identified in horse kidneys, with an average concentration of 257 μg/g on dried matter, while in liver it was sporadically present.

Characterization of experimental equine glanders

Considerable advances in understanding of the disease caused by Burkholderia mallei have been made employing a combination of tools including genetic techniques and animal infection models. The development of small animal models has allowed us to assess the role of a number of putative virulence determinants in the pathogenesis of disease due to B. mallei. Due to the difficulties in performing active immunization studies in small animals, and due to the fact that the horse is the target mammalian species for glanders, we have initiated experimental studies on glanders in horses. Intratracheal deposition of B. mallei produced clinical glanders with organisms being recovered from tissues of infected horses. The model should prove to be of considerable value in our ongoing studies on the pathogenesis and vaccine development for glanders.

Results of surgical treatment of colic in miniature breed horses: 11 cases.

To report on the outcome of surgical treatment of acute abdominal crises in miniature breed horses. Retrospective case series of miniature horses presented to the University Veterinary Centre, Camden with an acute abdominal crisis. Hospital records of all miniature horses that underwent ventral midline laparotomy for acute abdominal crisis between 1997 and 2001 were reviewed. The signalment, history, clinical signs, results of ancillary diagnostic procedures, location and type of intestinal lesion, treatment and outcome were retrieved from each case record. Long-term survival was determined by telephone interview of owners. Eleven miniature horses including five females and six males underwent ventral midline laparotomies for acute abdominal crisis during the study period. Ages ranged between 1 month and 19 years. Surgical findings included faecalith obstruction (seven horses), enterolith (one horse), strangulating lipoma of the descending colon (one horse), jejunal infarction (one horse), and caecal infarction (one horse). Long-term survival rate (minimum 12 months post surgery) was 55%. Six of eight horses with simple intraluminal obstructions survived, while the three horses with gastrointestinal lesions associated with vascular compromise were euthanased either at surgery (caecal infarction), or postoperatively, due to complications (strangulating lipoma of the descending colon, jejunal infarction). Postoperative complications in this study included impaction of the descending colon (two horses), diarrhoea (two horses), peritonitis (one horse), hyperlipaemia (two horses), incisional infection (two horses) and abdominal adhesions (one horse). Hyperlipidaemia was present in five of seven horses in which serum triglycerides were measured at presentation. Simple intraluminal obstructions of the large intestine were frequently encountered during exploratory laparotomy in miniature horses presented for acute abdominal crises, and their surgical treatment was associated with a good prognosis. In contrast, this study suggested that abdominal pain associated with vascular compromise of gastrointestinal tissues in miniature horses was associated with a poorer prognosis, consistent with reports in other horse breeds. Possible contributing factors to faecalith formation, including poor quality roughage, dental disease, and inadequate water consumption, should be recognised and avoided in miniature horses. Serum triglyceride concentrations should be measured in miniature horses presented for acute abdominal pain. If elevated, nutritional supplementation should be provided.

PATHOGENICITY OF A VENEZUELAN EQUINE ENCEPHALOMYELITIS SEROTYPE IE VIRUS ISOLATE FOR PONIES

The enzootic or endemic strains of Venezuelan equine encephalomyelitis (VEE) virus (ID, IE, IF, and II-VI) are considered avirulent. In 1993 and 1996, outbreaks of encephalitis occurred in the horse populations in the Chiapas and Oaxaca provinces of Mexico, respectively. In both instances, enzootic VEE virus subserotype IE was isolated from brain tissues of dead horses. The present study investigated the pathogenicity of the Chiapas viral isolate (NVSL VEE IE 93-42124) in ponies. Three ponies were inoculated intradermally with 4, 5, and 6 logs, respectively, of the NVSL VEE IE 93-42124 viral isolate. All ponies showed fluctuations in body temperature, encephalitis, and other signs of infection with VEE virus. Virus was isolated only from the blood of ponies from day 1 to day 3 postinfection. Microscopic examination of hematoxylin and eosin-stained tissue sections showed mild to moderate nonsuppurative encephalitis, perivascular cuffing by mononuclear cells, gliosis, and meningoencephalitis. Antibody (IgM) to VEE virus IE was unable to differentiate between various subserotypes of VEE I viruses (serotypes IAB, IC, ID, and IF). Virus neutralizing antibody titers to heterologous VEE I viruses were 10-100-fold less than those for NVSL VEE IE 93-42124 virus and Mena II, a human isolate of VEE IE virus. The study confirmed that NVSL VEE IE 93-42124 virus, which was isolated from a brain of a horse during an outbreak of VEE in Chiapas, Mexico, was pathogenic for ponies.

Effects of repeated biopsying on muscle tissue in horses.

The collection of muscle samples in horses to estimate their performance potential, adaptations to training and diagnosis of exertional myopathies is of increasing interest. This study was designed to examine whether repeated biopsying of the gluteus medius muscle at 7 week intervals alters morphology and muscle fibre variables in the sampling area. The gluteus had been biopsied 3 times previously, each biopsy separated by a 7 week interval. Seven weeks after the last biopsy, this study was initiated. Percutaneous needle biopsies were taken from left and right muscles at 2 depths (2 and 6 cm) and at 2 sites for each depth (22 and 25 cm from the tuber coxae) of 7 mature Thoroughbreds. The 22 cm site was located close (2 cm caudal) to an area of the muscle that had been biopsied previously. The 25 cm site was 5 cm apart from this area. A total of 52 samples were available for histology, electron microscopy and immunohistochemistry. The latter was used to study percentages, sizes and capillaries of muscle fibre types. Most muscle samples collected (75%) had normal morphology, but the remaining 25% showed signs of muscle repair. In some circumstances, they showed regenerative signs of complete muscle repair, while in others ineffective muscle repair (scar formation) was evident. Nevertheless, sufficient normal tissue was always available for measuring routine muscle variables. Samples collected 3 cm laterally apart showed large differences with regard to muscle fibre type variables examined. These results show that repeated muscle samples in intervals of 7 weeks do not have effects that would impair evaluation of muscle fibre variables for diagnosis of effectivity of conditioning programmes. Furthermore, they emphasise that the only way of keeping variations through sample collection technique small is to standardise all biopsying techniques accurately.

Magnetic resonance imaging application to live horse for diagnosis of tendinitis.

Six live horses with various stages of acute to chronic superficial digital flexor (SDF) tendinitis were examined using magnetic resonance imaging (MRI). In each case, MRI findings were compared to the corresponding ultrasonographic (USD) and histologic findings, to establish the usefulness of MRI. In the acute cases, lesions characterized by hemorrhage were well defined as high signal intensity on MRI and hypoechoic regions on USD. Chronic tendon fibrosis was slightly hyperechoic and difficult to distinguish from the normal tendon tissue around the original injury by using USD. In contrast, MRI visualized the chronic lesion as a low intensity signal, which could be distinguished from the black background of the normal SDF tendon tissue. This study clearly demonstrated MRI was the better imaging modality for the objective detection of chronic scar tissue in live horses. These findings, from living horses, suggest an advantage of MRI in the clinical application to diagnose tendinitis in cases where there is chronic scar tissue that is difficult to discern on USD.

Expression of interleukin-1beta in the digital laminae of horses in the prodromal stage of experimentally induced laminitis.

To study expression of interleukin-1beta (IL-1beta) in the digital laminae of horses in the prodromal stage of experimentally induced laminitis. 8 healthy adult horses with no signs of laminitis. Black walnut extract was administered via nasogastric tube to 4 horses, and water was administered to the remaining 4 (controls). Complete blood counts and physical examinations were performed every 30 minutes after administration of black walnut extract or water. General anesthesia was induced when total WBC count decreased by 30% in horses given the black walnut extract and 3 hours after water administration in control horses. The left forefoot was perfusion fixed with neutral-buffered 10% formalin, and paraffin-embedded sections of the digit were used for in situ hybridization with an equine-specific IL-1beta probe. IL-1beta mRNA expression was observed in perivascular cells of the small laminar venules and capillaries in all 4 horses given black walnut extract and in interstitial cells remote from the microvasculature in 1 of the 4. Other cellular components of the laminar tissue and cellular components of the digital arterioles and veins did not exhibit IL-1beta mRNA expression. Expression of IL-1beta mRNA was not detected in laminae from control horses. Results suggest that IL-1beta mRNA is expressed by perivascular cells in the laminar tissues of horses in the prodromal stage of experimentally induced laminitis. This provides evidence of an inflammatory process during the prodromal stage of laminitis, indicating that local digital proinflammatory cytokine expression may be an initiating factor in laminitis.

Concentrations of elastinolytic metalloproteinases in respiratory tract secretions of healthy horses and horses with chronic obstructive pulmonary disease.

To determine whether samples of tracheal epithelial lining fluid (TELF) obtained from horses have elastinolytic activity characteristic of metalloproteinases, to compare elastinolytic activity in TELF obtained from healthy horses and horses with chronic obstructive pulmonary disease (COPD), and to determine whether chemically modified tetracycline-3 (CMT-3) inhibits elastinolytic activity in TELF ANIMALS: 10 horses with COPD and 10 healthy control horses. Zymography and fluorometry were used to measure elastinolytic activity, and EDTA was used to inhibit elastinolytic activity and verify that the activity was attributable to metalloproteinases. Possible inhibition of elastinolytic activity with CMT-3 was studied in vitro. Elastinolytic activity was found in TELF obtained from all horses, and this activity was significantly higher in TELF obtained from horses with COPD than in TELF obtained from healthy horses. For all samples, EDTA and CMT-3 inhibited elastinolytic activity. Elastinolytic activity is detectable in TELF obtained from horses and seems to be attributable to metalloproteinases. Elastinolytic activity in TELF is significantly inhibited by CMT-3. Elastinolytic activity in TELF can be detected by means of zymography or fluorometry. Increased elastinolytic activity may reflect destruction of pulmonary tissue in horses with COPD. Chemically modified tetracyclines such as CMT-3 may provide an additional treatment possibility for horses with COPD.

Cadmium in organs and tissues of horses slaughtered in Italy

The cadmium content of muscle, liver, kidney and blood samples from 62 horses slaughtered in Italy was investigated. Cadmium was determined by graphite furnace atomic absorption spectrometry (GFAAS) after wet digestion of the samples. The mean and median contents of all samples were (on a fresh weight basis) 75 and 41 μgkg-1 for muscle, 2.46 and 2.10 mgkg-1 for liver, 20.0 and 13.5 mgkg-1 for kidney. The cadmium level in blood samples was always below 6 μgl-1. The cadmium concentrations in muscle, liver and kidney were found to be related to the life span of the specimens and increased with age. Females exhibited higher levels than males, but this difference was significant only in the case of muscle tissue. The geographical origin was recognized as the main factor influencing the cadmium content of the equine specimens analysed. The differences between horses coming from the three main breeding countries considered in this study (Poland, Lithuania, Hungary) were marked and statistically significant. The average intake of cadmium from equine meat was estimated for the general population and for population groups resident in areas with high consumption of this food item. While the cadmium intake from equine meat for the average consumer accounts for about 1% of the total cadmium intake estimated for Italy, in the latter case the enhanced consumption of equine muscle is often accompanied with the consumption of substantial quantities of equine liver and this may lead to high cadmium intakes.

Distribution of cells immunopositive for AM-3K, a novel monoclonal antibody recognizing human macrophages, in normal and diseased tissues of dogs, cats, horses, cattle, pigs, and rabbits.

The monoclonal antibody AM-3K, which was developed using human pulmonary macrophages as the immunogen, immunocytochemically labels most human macrophages except for blood monocytes and dendritic cell populations. AM-3K also shows cross-reactivity in some animal species. To evaluate the usefulness of AM-3K, the present study investigated the detailed distribution of AM-3K-immunopositive macrophages in normal and diseased tissues of dogs, cats, horses, cattle, pigs, and rabbits. Zamboni's solution-fixed, paraffin-embedded sections were the most available for the immunocytochemistry with AM-3K. In all animal species examined, AM-3K labeled most macrophages in splenic red pulp, lymph node sinuses and thymus, and tissue macrophages in the interstitium of various organs and sites such as the kidneys, lungs, heart, pancreas, intestines, and skin. Alveolar macrophages and perivascular microglial cells were also immunoreactive for AM-3K. Interestingly, Kupffer cells of dogs, cats, and horses were labeled for AM-3K, but those of cattle, pigs, and rabbits were not. Furthermore, in tumor tissues and inflammatory lesions such as liver fibrosis and encephalomalacia that were obtained from dogs, infiltrating macrophages were stained with AM-3K, but not all infiltrating macrophages reacted to AM-3K. In addition, only 30-50% of pulmonary and peritoneal macrophages obtained from cats and dogs were reactive for AM-3K. AM-3K did not react with blood monocytes, dendritic cell populations, and osteoclasts. These observations indicate that AM-3K specifically labels most exudate and tissue macrophages in the animal species examined. However, the expression of antigens recognized by AM-3K on macrophages may be dependent on differential maturation stages or different functions evoked by some conditions. AM-3K immunoreaction products were seen on the cytoplasmic membrane of macrophages by immunoelectron microscopy. AM-3K would be useful for detection of macrophage populations in the animal species examined here.

Correlation of clinical score, intrapleural pressure, cytologic findings of bronchoalveolar fluid, and histopathologic lesions of pulmonary tissue in horses with summer pasture-associated obstructive pulmonary disease

To correlate clinical score, intrapleural pressure, cytologic findings of bronchoalveolar lavage fluid (BALF), and histologic lesions of pulmonary tissue in horses affected with summer pasture-associated obstructive pulmonary disease (SPAOPD). 8 adult horses affected with SPAOPD and 6 adult horses without evidence of respiratory tract disease. Clinical score, change in intrapleural pressure (deltaPpl) during tidal breathing, results of cytologic examination and bacteriologic culture of BALF, and results of histologic examination of pulmonary parenchyma were evaluated. Clinical scores for SPAOPD-affected horses (median, 5.75; range, 4.0 to 7.5) were significantly greater, compared with clinically normal horses (median, 2.0; range, 2.0 to 3.0). Cytologic examination of BALF from SPAOPD-affected horses revealed predominantly nondegenerate neutrophils. Histologic lesions were identified throughout pulmonary tissue and included severe accumulation of mucus and neutrophils within the small airways, metaplasia of bronchiolar goblet cells, and mild peribronchial infiltrate. Histologic examination of specimens collected via percutaneous biopsy was predictive of disease and corresponded to findings at postmortem examination. Clinical score and deltaPpl were highly correlated with mucus accumulation in the airways of affected horses. Peribronchial inflammatory infiltrate correlated with percentage of neutrophils in BALF of affected horses. Clinical scoring and deltaPpl provided valid estimates of disease severity. Findings from cytologic examination of BALF of SPAOPD-affected horses varied, although, in most instances, it was diagnostically useful. Severe mucus accumulation in the airways was the most remarkable histopathologic finding in SPAOPD-affected horses. Examination of biopsy specimens collected from pulmonary parenchyma was consistently useful in diagnosing SPAOPD.