Antibody-containing cells and specialised epithelial cells in the bovine teat

Tissue from the ends of teats of dry, periparturient and lactating cows were studied using light and electron microscopy. Accumulations of infiltrating leucocytes mainly in the folds of the distal rosette of the teat cistern (Furstenberg's rosette) were detected; plasma cells predominated. The latter were classified by the type of immunoglobulin (Ig) which they synthesised. Plasma cells synthesising IgG1 were found to be the major antibody producing cell type of the teat. Neither the number of stromal plasma cells present nor the class of Ig which they synthesised was significantly altered by changes in mammary gland secretory activity. Scanning electron microscopy revealed areas of epithelium of Furstenberg's rosette that contained cells differing in surface characteristics from epithelial cells of adjacent areas of the teat cistern.     

Distribution of immunoglobulin-bearing leukocytes in bovine mammary tissue infected chronically with Staphylococcus aureus

Mammary parenchymal and test end tissues from cows with chronic Staphylococcus aureus mastitis were examined to determine the distribution of immunoglobulin (Ig) G1- and IgG2-bearing leukocytes. Leukocytes bearing IgG2 predominated in S. aureus infected quarters, with highest numbers observed at the Furstenberg's rosette followed by streak canal and parenchymal tissue areas. Significantly more IgG1- and IgG2-bearing leukocytes were observed at the Furstenberg's rosette and significantly more IgG2-bearing leukocytes were observed at the streak canal of S. aureus infected quarters compared to uninfected quarters. Receptors for cytophilic IgG on neutrophils and macrophages may increase efficiency of phagocytosis and improve the antimicrobial effectiveness of these cells in treat end tissues.     

Blood flow to the distal part of the teat (mammary papilla) of lactating dairy cows

Relative blood flow to tissues of the distal part of the teat (mammary papilla) in 5 lactating dairy cows was determined, using 15-microns nonradioactive carbonized microspheres. Highest relative blood flow occurred in the epithelial region (zone A) of the teat canal (papillary duct) which comprised both teat canal epithelium and papillated portion of the stratum papillare. Blood flow to these tissues was more than 4 times greater than blood flow to equivalent tissues of the mucosal rosette. The high rate of metabolic activity indicated by this relatively high blood flow may be required to support secretion of antimicrobial substances and continual synthesis of epithelial cells to replace those lost during milking.     

Scanning electron microscopy-aided observations on and therapy of teat canal infections

An examination of teat canal swabs established that 51 teat canals out of 68 quarters of machine-milked cows were colonized by Staphylococcus aureus. Only 31 of these quarters yielded milk from which S. aureus could be cultured, and 6 out of the 31 produced milk containing somatic cell counts in excess of 500 000/ml. No inhibitory substances could be detected in milk samples 12 h after 10 mg of sodium cloxacillin had been deposited in the test canal on 1-4 successive occasions. Teat canal swabs and milk sample cultures of the same quarters became and remained bacteriologically negative for at least a week after the last treatment. Six quarters, which according to the International Dairy Federation criteria were suffering from subclinical mastitis, became negative after local teat canal therapy. Scanning electron micrographs of one infected teat canal revealed the presence of cocci in depressions and crevices on the epithelial surface, suggesting that such cocci are not always flushed out into milk samples. Teat canal therapy should make a marked contribution to the control of bovine mastitis.     

Changes in the bovine teat canal during the nonlactating period and early lactation, as measured by teat canal impressions.

Changes in dimensions of impressions of the lumen of the teat canals of 13 cows were examined at 17 intervals during the nonlactating period and early lactation. Impressions were made of teats of 2 diagonally opposed quarters of each cow, using dental impression material. Impression length was measured and cross sections of the impressions at the proximal (distal to Furstenburg rosette), distal (proximal to the teat orifice), and middle (midway between the 2), portions of the teat canal were prepared. Cross sections were photographed and enlarged, and circumference and area were determined by use of planimetry. Effects of making repeated impressions during the nonlactating period and early lactation on new infection rates and somatic cell counts were also assessed. Mean length of teat canal impressions decreased between days 0 and 3 of involution and during the prepartum periods. Depending on the level from which they were taken, cross-sectional areas of impressions tended to increase or increased significantly during the period of involution and again in the prepartum period. Significant changes in cross-sectional area were not observed during early lactation. Changes in circumference of proximal, middle, and distal cross sections followed trends similar to area measurements, but were more variable and differences were less statistically significant. On the basis of our findings, we suggest that heightened susceptibility to new infection during mammary involution and the prepartum period may be attributable, in part, to changes in the patency of the teat canal. Making impressions repeatedly throughout the nonlactating period and early lactation did not affect the number of new intramammary infections.     

Effects of different teat inserts on wound healing of experimentally incised streak canal in non-lactating cattle

The recurrence of reduced milk flow is a common sequela after placement of teat inserts in the streak canal as a treatment for teat injury. We evaluated the effects of three types of commercial teat inserts on wound healing. Thirty-two normal streak canals of eight cows were incised longitudinally using a teat knife. Then, a wax-bougie, silicone self-retaining cannula, and catgut teat dilator were placed in each cow for 7 days. No insert was placed on the remaining teat as a control. Histopathological examination revealed that granulation polyps with squamous metaplasia developed in the area around the rosette of Furstenberg in most teats in which silicone cannulas and catgut teat dilators were placed, whereas the controls and the teats with wax-bougies healed with less tissue reaction. This study suggests that the placement of irritating inserts, such as a silicone cannula and catgut teat dilator, interfere with wound healing.     

Teat tip reconstruction by supernumerary teat autotransplantation in cattle

OBJECTIVE: Evaluation of use of a supernumerary teat as a pedicle graft to repair experimental teat tip damage in cattle. STUDY DESIGN: Experimental study. ANIMALS: Mature, non-gravid hybrid cows with > or =1 supernumerary teat. METHODS: The main teat and adjacent supernumerary teat were examined for patency by ultrasound with a 8 MHz linear array transducer. The tip of the main teat was resected at the junction of cistern and canal. The supernumerary teat was partially resected semi-circumferentially at the cranial aspect of the base to maintain vascular supply and transplanted by end-to-end anastomosis. The pedicle of the supernumerary teat graft was amputated in stages starting at 14 days, again at 16 days and separated at 18 days. Reconstructed teat patency was evaluated at intervals by ultrasonography and confirmed at 50 days by histopathology. Repeated measures ANOVA was used to compare the measurements of luminal diameter between days; significance was set at P<.05. RESULTS: All reconstructed teats were patent. Decreased luminal diameters were detected at 25, 32, 39, and 46 days by ultrasonography. On histopathology, granulation and epithelial (mucosal) proliferation contributed to luminal reduction. CONCLUSIONS: In this experimental model of an acute damage to a teat tip, supernumerary teat grafting was successfully used to restore teat anatomy. CLINICAL RELEVANCE: Supernumerary teat pedicle grafting may be considered as a salvage technique for reconstruction of a damaged bovine teat in cows that have an adjacent patent supernumerary teat. Function of the reconstructed teat in a lactating cow remains unknown.     

Studies of endotoxin-induced neutrophil migration in bovine teat tissues, using indium-111-labeled neutrophils and biopsies.

Neutrophil migration through bovine teat tissues into the teat cistern, after endotoxin infusion into the teat cistern, was determined in vivo by 2 experimental procedures, indium-111 labeling of blood neutrophils, and obtaining multiple biopsy specimens from the teat cistern tissues. In both experiments, the number of leukocytes in the teat cistern flushing samples was continuously measured. A lag phase of approximately 1 hour was required between endotoxin infusion into the teat cistern and the first observed neutrophil accumulation in the teat tissues. The rate of neutrophil accumulation in the teat tissues was highest between postinfusion (PI) hours 1 and 2, and the accumulation process ceased after PI hour 3. Neutrophils migrated toward the epithelium, and intraepithelial neutrophils were observed beginning approximately 2 hours after infusion, which coincided with the first influx of cells into the teat cistern. The cell influx into the teat cistern increased continuously up to PI hour 3, peaked between PI hours 3 and 5, and was close to preinfusion value at PI hour 22. Use of indium-111-labeled neutrophils in the study of the inflammatory process provides a reliable noninvasive method to quantify cell migration in vivo. Use of biopsies allows quantification of the number of cells in different tissue areas, but has the disadvantage of being invasive. These 2 procedures complement each other, and could be of use in future studies of the local inflammatory process.     

Effects of teat cistern mural biopsy and teatoscopy stab versus longitudinal incision with or without tube implant on incisional healing in lactating dairy cattle

Effects of teat cistern mural biopsy and full-thickness stab and longitudinal incisional healing were evaluated experimentally on clinically normal teats in 12 lactating dairy cattle. Each teat on each cow was assigned by Latin-square design to 1 of 4 surgical interventions: (I) teatoscopy only; (II) teatoscopy, stab incision, and mural biopsy; (III) longitudinal incision and mural biopsy; and (IV) longitudinal incision, mural biopsy, and tube implantation. Teatoscopy was done with a 4-mm OD arthroscope introduced through the teat canal and attached to a television camera. Teatoscopy was quicker to perform and provided a more detailed videotaped examination of the teat and gland cistern, compared with gross inspection through a longitudinal incision. In intervention-II cows, the Ferris-Smith biopsy instrument jaws introduced through a longitudinal 1-cm midteat stab incision were easy to visualize and manipulate accurately. Stab incisions closed with only 1 or 2 skin sutures healed without complications in all 12 teats. On palpation, stab incisions were significantly (P less than 0.01) less thick than longitudinal incisions at 8 weeks and were microscopically indistinguishable from the normal tissue. However, in 24 teatoscopically examined teats, 9 (38%) had microscopic evidence of teat canal injury and 12 (50%) of the quarters developed mastitis. This was attributed to trauma resulting from introduction of the arthroscope through the teat canal. Intervention III yielded satisfactory results with the least complications. All 12 longitudinal incisions healed by primary intention, and all teats remained patent. Mastitis developed in 4 (33%) quarters. Intervention IV caused considerable complications associated with the tube implant and no improvement in biopsy site healing, compared with interventions II and III. Eleven longitudinal incisions healed by primary intention. One incision dehisced, 2 (17%) tube implants dislodged, 2 (17%) became obstructed proximally, and irritations of the mucous membrane developed in 2 teats proximally and in 6 teats distally. Mastitis developed in 6 (50%) quarters. Longitudinal incisions healed with moderate submucosal fibrosis. All sutured incisions had multifocal microgranulomata in which suture material was in various stages of degradation. At 8 weeks, localized teat wall thickening could be detected at incisional and biopsy sites, but did not obstruct milk flow. Excessive granulation tissue was at the biopsy sites (72 total) at 2 weeks, and at this time, the sites were partially covered by metaplastic squamous epithelium. However, by 8 weeks, 71 (98%) of the areas were replaced by fibrous tissue with minimal protrusion into the teat cistern.     

Milk flow and udder health in cows after treatment of covered teat injuries via theloresectoscopy: 52 cases (2000-2002)

OBJECTIVE: To determine milk flow, somatic cell counts (SCCs), and the incidence of clinical mastitis in cows that had undergone theloresectoscopy for treatment of teat stenosis caused by mucosal detachment in the region of the streak canal or Fürstenberg's rosette. DESIGN: Retrospective study. ANIMALS: 52 cows with teat stenosis that were treated via theloresectoscopy. PROCEDURE: Medical records of eligible cows were reviewed. Additional data regarding milking ease, SCC, development of clinical mastitis of the affected gland, and whether the cow remained in the herd were collected via owner-completed questionnaires. RESULTS: 49 of 52 questionnaires were completed. At referral, teat sinusitis was diagnosed in 29 of 52 cows. Milk flow was normal in 38 of 41 treated teats at discharge and in 24 of 40 during the next lactation. Thirteen of 49 cows were culled during the next lactation because of abnormal udder health. High SCC and teat sinusitis at referral and development of clinical mastitis during the 10-day period after surgery resulted in high SCCs in the remainder of the current lactation. The incidence of clinical mastitis during the remainder of the current and during the next lactation was higher in cows that had teat sinusitis at the time of surgery, compared with those that did not. CONCLUSIONS AND CLINICAL RELEVANCE: Teat stenoses resulting from mucosal lesions in the region of the streak canal or Fürstenberg's rosette may be successfully treated via theloresectoscopy. Inflammation of the teat sinus and gland at the time of surgery may adversely affect udder health.     

Tuberculin elicited cellular immune response in the lactating bovine mammary gland vaccinated intramammarily with Mycobacterium bovis

The development of a local antigen-specific sensitivity was monitored histologically and in secretions of the bovine mammary gland. Three cows in mid-lactation were immunized by injecting 50 microliter of a killed Mycobacterium bovis vaccine into the dorsal secretory tissue of the rear mammary glands; two cows served as unvaccinated controls. Ten weeks after vaccination, all cows were challenged by intramammary infusion of 1.0 microgram tuberculin in 5 ml phosphate-buffered saline (PBS). Three quarters of each cow received tuberculin at 72, 48, and 24 hours before slaughter; a control quarter received PBS at 72 hours. Vaccinated cows exhibited an intense, local cellular reaction to tuberculin in teat-end tissues at all times post infusion; PBS-infused glands were normal. A moderate leukocyte response in parenchymal tissues adjacent to the gland cistern of tuberculin-infused quarters was observed, but deep parenchymal tissues were normal; no effect on milk yield was found. Tuberculin-infused quarters exhibited histological responses in teat cisternal tissues similar to those in delayed-type hypersensitivity reactions. Leukocytic accumulation was primarily macrophages and lymphocytes with few neutrophils. Erythema was observed in the distal half of the cistern, and fibrin deposits were found in subepithelial connective tissues. The epithelium, although distended with leukocytes, was intact and numerous mitotic figures were present. Unvaccinated cows showed no response to challenge. Results demonstrated a marked and specific cellular response in sensitized cows to challenge with tuberculin.     

Immunoglobulins, lysozyme and lactoferrin in the teat and udder of the dry cow during endotoxin-induced inflammation.

Immunoglobulins (Ig) and antibacterial proteins like lysozyme and lactoferrin are components of the humoral defence against infections. Changes in Ig, lysozyme and lactoferrin concentrations during endotoxin-induced inflammation in the test cistern and udder quarter of the dry cow were studied. Surgical closure of the passage between teat and udder cisterns enabled studies of reactions in the teat cistern without interference of the mammary gland. After endotoxin infusion, IgG1, IgG2, lysozyme, and to some extent IgM, increased in the teats and udder quarters, and were positively correlated with changes in somatic cell counts. No significant changes were observed in IgA or lactoferrin. The origin and significance of Ig, lysozyme and lactoferrin in the bovine teat and udder are discussed. Ig probably originated both from serum and from local plasma cells, while leukocytes appeared to be the source of lysozyme during inflammation. Secretory epithelium appeared to be the source of lactoferrin. Support for this theory was the almost total absence of lactoferrin in teat cistern samples.     

Effects of Staphylococcus aureus mastitis on bovine mammary gland plasma cell populations and immunoglobin concentrations in milk

Bovine mammary tissue and milk samples were examined to determine effects of chronic Staphylococcus aureus mastitis on the humoral immune response. Parenchymal and teat end tissues from lactating bovine mammary glands were stained immunohistochemically to determine distribution of immunoglobulin (Ig) G1-, IgG2-, IgA-, and IgM-producing plasma cells. Numbers of all Ig-producing plasma cells tended to be higher in tissues from S. aureus infected quarters compared with controls, but most differences were not statistically different. Numbers of IgG1-producing plasma cells at the Furstenberg's rosette area of infected quarters were significantly (P less than 0.05) higher than uninfected quarters. There were no significant differences in concentrations of Ig isotypes in milk from S. aureus infected and uninfected quarters. Data suggest that the antigenic effect of chronic S. aureus infection on the humoral immune response of the bovine mammary gland is minimal. Persistency of S. aureus infection may result, in part, from suboptimal stimulation or immunosuppression of the mammary immune system.     

Inflammatory reactions in the teat and udder of the dry cow

The inflammatory reactions in the teat and udder of the dry cow were studied by total and differential somatic cell counts (SCC) and by measuring bovine serum albumin, N-acetyl-beta-D-glucosaminidase (NAGase), plasminogen and plasmin. The teat and udder cisterns were surgically separated from each other in two udder quarters of each cow. Salmonella endotoxin was infused in one teat cistern and one udder quarter, and saline was infused in one teat cistern and one udder quarter. The inflammatory response was followed by several samplings post infusion. The reactions in the dry udder quarters were mainly in line with the results of similar studies in lactating glands. The differential SCC and the NAGase results were, however, somewhat different. The teats were capable of a strong inflammatory response. Reactions different from those seen in the glands were observed with regard to permeability changes and NAGase. The experimental model used showed promising results and is suitable for further studies of the inflammatory process.     

Radiographic method for anatomic study of the teat canal: characteristics related to resistance to new intramammary infection during lactation and the early dry period.

An in vivo radiographic method to determine teat canal anatomy has shown that resistant quarters had teat canals with a smaller diameter than that of susceptible quarters. The length of the teat canal did not appear to be related to resistance to new intramammary infections. These findings relate to new infection caused by Aerobacter aerogenes, Streptococcus agalactiae, and Staphylococcus aureus. Quarters guarded by teat canals with larger diameter were less resistent to new infection during both lactation and the early dry period compared with quarters guarded by teat canals with small diameter.     

The susceptibility of bovine udder quarters colonized with Corynebacterium bovis to experimental infection with Staphylococcus aureus or Streptococcus agalactiae.

Twenty bovine udder quarters colonized with Corynebacterium bovis SR6 and 20 uncolonized quarters were challenged by inoculation of Staphylococcus aureus Newbould 305 (ATCC 29740) into the teat cistern. The percentage of infection in quarters colonized with C. bovis (50%) was significantly lower than that in controls (100%). By similar challenge no significant difference was observed between the percentage of infection with Streptococcus agalactiae ATCC 27956 in 33 quarters colonized with C. bovis (70%) compared to 33 controls (87.9%). A total of 37 quarters colonized with C. bovis and 37 control quarters were challenged with Staph. aureus Newbould 305 (ATCC 29740) and Maxi (ATCC 27543) and Strep. agalactiae (ATCC 27956) by exposure of the teat orifice. The percentage of teat ducts colonized with C. bovis which became infected with either pathogen was not different from that for controls.     

Bovine serum albumin and cell counts in the diagnosis of subclinical udder infection

Summary

Puncture of the milk cisterns was performed in 120 bacteriologically positive quarters of forty‐seven lactating dairy cows on three farms. This method was used to determine whether the existing infection was an infection of the teat canal or one of the udder. The results were related to the concentration of bovine serum albumin (BSA) and the cell count in the milk. Of the bacteriologically negative quarters, both BSA levels (in 91 per cent of the quarters the BSA concentration was 0.20 mg. per ml. of milk or less) and cell counts (92 per cent contained less than 500,000 cells per ml. of milk) were low. In cases of udder infection with primary pathogenic bacteria there was a marked increase in cell count (90 per cent more than 500,000 cells per ml. of milk), whereas the increase in BSA was rather small (51 per cent still contained 0.20 mg. BSA per ml. of milk or less). While the difference in cell counts of milk from quarters with udder infections and teat canal infections with primary pathogenic bacteria was significant, the difference between the BSA levels of these two groups was not. Therefore, the cell count supplies more reliable information than does the BSA level of the milk. Of all infections, 23 per cent were found to be infections of the teat canal.     

Experimental colonization of the bovine teat duct with Corynebacterium bovis and the effect on milk somatic cell counts.

Colonization with Corynebacterium bovis was established in 59 of 64 (92%), 58 of 59 (98%) and 19 of 34 (56%) of uninfected bovine mammary quarters following inoculation of 83.3 X 10(4) colony-forming units (CFU) of the organism into the teat cistern, 4.7 X 10(3) CFU 5 mm into the teat duct or by exposure of the teat orifice to a milk culture containing 1.6 X 10(7) CFU/mL respectively. Mean somatic cell counts for foremilk samples from 122 quarters were significantly higher after colonization with C. bovis (145,900/mL) compared to before exposure (130,900/mL).     

Endoscopic, pathologic-anatomic and histologic findings in the bovine teat. 2. Changes in the area of Fürstenberg's rosette

In the present study endoscopically diagnosed changes of the Fürstenberg's rosette were examined histologically. For this purpose the teats of 200 slaughtered cows were inspected. In 19 cases proliferations in the region of the Fürstenberg's rosette were found. Additionally, tissue samples were taken from the Fürstenberg's rosette of 26 cows which showed milk flow disorders due to stenoses of this part of the teat. Teats of slaughtered cows as well as biopsy specimens were fixed in 5% formaldehyde and embedded in paraffin and in plastic. All specimens were stained according to H.E., Giemsa and Turnbull, respectively. Histologically, the proliferations of the Fürstenberg's rosette consisted of fibrovascular tissue (granulation tissue) covered by keratinized squamous epithelium (teat canal epithelium) in eleven cases. In the other cases double-layered cuboid epithelium (cisternal epithelium) was found additionally. The formation of granulation tissue and deposition of blood pigment was observed exclusively in areas covered by stratified epithelium. Therefore a traumatic lesion of the teat canal was supposed to be the cause of the histological findings. In contrast to several reports in the literature, however, no indications of an inversion of the teat canal epithelium were found. On the basis of these findings, the hitherto assumed idea of pathogenesis of proliferations of the Fürstenberg's rosette was modified and a new pathogenesis pattern was developed.     

A study of the development of endotoxin-induced inflammation in the bovine teat.

Endotoxin-induced local inflammation was studied by frequent samplings in a bovine teat cistern model, which provides a unique possibility for in vivo studies of reactions in the teat without interference from the mammary gland. A rapid inflammatory response of rather short duration was elicited after endotoxin administration. An initial increase in the concentrations of bovine serum albumin and N-acetyl-beta-D-glucosaminidase, indicating a disturbance in the epithelial integrity, was observed between 1 and 1.5 h post infusion (p.i.). Approximately 0.5 h later, the first influx of leukocytes, mainly neutrophils, appeared. The neutrophils tended to enter the teat cistern in several peaks occurring between 2.5 and 5 h p.i. The sampling procedure decreased the accumulation of cells by approximately 40%, which was probably due to the removal of inflammatory mediators at an early stage. The parallel use of 2 teats instead of 1 had no major influence on the inflammatory process. This teat cistern model and the experimental procedure used should be suitable for further studies of the development of local inflammation.