Efficacy of non-antibiotic treatment options for digital dermatitis on an organic dairy farm.

The objective of this study was to evaluate the efficacy of two non-antibiotic treatment options for digital dermatitis (DD) on an organic certified dairy farm. A randomized clinical trial was conducted using 70 multiparous Holstein cows with an early DD lesion at a USDA certified organic dairy farm in Northern Colorado, USA. Cows were enrolled in the study based on the presence of early DD lesions (scores M1 and M2) and randomly assigned to one of three treatments: (1) topical application of copper sulfate and iodine (CUI); (2) topical application of honey and iodine (HOI); and (3) control subject to no treatment (CON). Cows were evaluated at enrolment and on days 3, 12, 28, and 120 post treatment for pain and lesion size and received a locomotion and a lesion score. Cure was defined as the transition from active to non-active stages (M1/M2 to M0 or M4). The formulations had variable effects on the treatment of DD. The cure rate was numerically higher for CUI on all follow up days. The proportion of cows experiencing pain on d3 after treatment was greater in CON, followed by HOI and CUI. However, this proportion increased in HOI during the follow up period. The CUI group had a greater reduction in lesion size and larger lesions persisted in HOI. Non-antibiotic treatment formulations were partially effective in the treatment of DD in organic dairy cows: The two non-antibiotic formulations resulted in an earlier transition to mature lesions compared with the control group. The CUI combination was the most effective treatment in reducing lesion size, pain, and lameness in affected cows. However, this combination had short-term efficacy, which did not persist throughout the duration of the study. The HOI combination produced only transient reduction in lesion size.

Effects of silymarin on p65 NF-κB, p38 MAPK and CYP450 in LPS-induced hoof dermal inflammatory cells of dairy cows.

BACKGROUND: Laminitis is considered as one of the most important causes of hoof lameness in dairy cows, which can lead to enormous economic losses. However, the etiology and pathogenesis of laminitis have not been clarified yet. Besides, it is of great significant to find alternative herbs for the prevention and treatment of dairy hooves to avoid the antibiotic abuse. In this study, the primary hoof dermal cells of dairy cows were isolated, the inflammatory model was induced by LPS, and treated with silymarin to find whether silymarin has protective effect on the inflammatory dermal cells. The viability of dermal cells, the levels of IL-1ß and TNF-α, the degree of p65 NF-κB and p38 MAPK phosphorylation, the expressions of CYP3A4 and CYP1A1 were measured. RESULTS: Hoof dermal cells of dairy cows were successfully isolated and cultured by tissue adherent culture method. Certain concentrations of LPS can increase the levels of IL-1ß and TNF-α, promote the phosphorylation of p65 NF-κB and p38 MAPK, and inhibit the mRNA expressions of CYP3A4 and CYP1A1. The optimal concentration for LPS to establish a hoof dermal cells inflammatory model was 10 µg/mL. Certain concentrations of silymarin can markedly decrease the secretions of IL-1ß and TNF-α, inhibit the phosphorylation of p65 NF-κB and p38 MAPK, and promote the mRNA expressions of CYP3A4 and CYP1A1 in LPS-induced dermal inflammatory model. CONCLUSIONS: LPS can be used for inducing the hoof dermal cells inflammatory model of dairy cows. Silymarin has protective effects on the LPS-induced inflammatory model.

Evaluation of the promoting effect of soluble cyclodextrins in drug nail penetration.

Soluble derivatives of ß-cyclodextrin (CD) have a high capacity to solubilise hydrophobic molecules and to interact with proteins and membrane component. As consequence CD derivatives shows a significant activity as drug absorption enhancers through different delivery routes, such as the oral, nasal, ocular or topical route. In this paper, the effect of two CD derivatives -methyl-ß-cyclodextrin (MBCD) and hydroxypropyl-ß-cyclodextrin (HPB)- on the structure and permeability of the nail plate has been studied using the drug model ciclopirox olamine. Results shows that MBCD and HPB interacting with the nail plate components, modifying their microporous structure and swelling characteristics. The ability of the cyclodextrins to interact with aromatic amino acids and to stabilise and unfold protein structures could be the most likely mechanisms responsible of the nail microstructure modifications. Aditionally CD allows to increase the soluble dose of ciclopirox olamine in aqueous lacquers made with poloxamer and N-acetylcysteine via the formation of high solubility complexes with the drug. Finally the studies of diffusion and penetration obtained using bovine hoof model confirm the enhancing effect of the cyclodextrins on the penetration and accumulation of the drug in the nail structure. Results shows the great potential of the CD for the elaboration of aqueous based nail lacquers containing hidrofobic drugs.

Comparison of effects of routine topical treatments in the milking parlor on digital dermatitis lesions.

Digital dermatitis (DD), an infectious bacterial disease affecting the feet of dairy cattle, can cause lameness and decrease milk production, fertility, and animal welfare. Current DD treatment typically involves routine hoof trimming and topical antibiotics. Several nonantibiotic commercial topical products are used for controlling DD lesions; however, there is limited or no evidence regarding their effectiveness. The objectives of this study were to evaluate 2 commercially available topical applications on their ability to (1) clinically cure active DD lesions to nonactive lesions and (2) prevent recurrence of active DD lesions. Ten farms were visited weekly. In the milking parlor, the hind feet of lactating cattle were cleaned and scored (M-stage scoring system). Cattle with DD lesions at the first visit were randomly allocated to 1 of 4 treatment groups: positive control (tetracycline solution), HealMax (AgroChem Inc., Saratoga Springs, NY), HoofSol (Diamond Hoof Care Ltd., Intracare BV, Veghel, the Netherlands), and a negative control (saline). All products were applied to lesions using a spray bottle. Tetracycline, HealMax, and HoofSol had a higher probability of clinical cure for active lesions compared with saline 1 wk after the first treatment (wk 1), with 69, 52, and 79% clinical cure of active lesions, respectively, compared with 34% with saline. At wk 7, the probability of clinical cure for active lesions was 10, 33, 31, and 45% of lesions treated weekly with saline, tetracycline, HealMax, and HoofSol, respectively (no difference among treatments). The substantial clinical cure with saline highlighted the potential importance of cleaning feet. In wk 1, treatment with saline, tetracycline, HealMax, and HoofSol resulted in a probability of recurrence of active DD lesions of 9, 11, 11, and 8%, respectively, with no product being superior to saline. After 7 wk, the probability of recurrence of active lesions was 5, 7, 6, and 6% for saline, tetracycline, HealMax, and HoofSol respectively, with no difference among groups in wk 7. These results provide alternatives to antibiotics for treatment of DD lesions and highlight the potential importance of cleaning feet in the milking parlor.

Analgesic effects of intraneural injection of ethyl alcohol or formaldehyde in the palmar digital nerves of horses.

OBJECTIVE: To determine analgesic effects of intraneural injection of ethyl alcohol or formaldehyde in the palmar digital nerves of horses. ANIMALS: 6 horses. PROCEDURES: Ethyl alcohol was injected in the medial palmar digital nerve of 1 forelimb, and formaldehyde was injected in the contralateral nerve. The lateral palmar digital nerve in 1 forelimb was surgically exposed, but not injected, and the contralateral lateral palmar digital nerve was not treated. For each heel, severity of lameness in response to experimentally induced heel pain (lameness score and peak vertical force), thermal reaction time, and heel skin sensitivity scores were recorded. Heel pain was experimentally induced by advancing a threaded bolt through a custom-made horseshoe to apply pressure to the palmar horned aspect of the hoof. Horses were followed up for 112 days, when a subset of nerves was sampled for histologic analysis. RESULTS: Alcohol and formaldehyde significantly reduced all measures of heel pain, and analgesia was evident over the 112 days of the study. Pastern circumference was significantly greater for formaldehyde-treated than for alcohol-treated limbs. Histologic evaluation showed preservation of nerve fiber alignment with an intact epineurium, loss of axons, axon degeneration, fibrosis, and inflammation in alcohol-treated and formaldehyde-treated nerves. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that intraneural injection of either ethyl alcohol or formaldehyde in the palmar digital nerves of horses resulted in substantial, but partial, heel analgesia that persisted for at least 112 days. No advantage of formaldehyde over alcohol was found, and formaldehyde resulted in greater soft tissue inflammation.

Effect of dietary nonstructural carbohydrate content on activation of 5'-adenosine monophosphate-activated protein kinase in liver, skeletal muscle, and digital laminae of lean and obese ponies.

BACKGROUND: In EMS-associated laminitis, laminar failure may occur in response to energy failure related to insulin resistance (IR) or to the effect of hyperinsulinemia on laminar tissue. 5'-Adenosine-monophosphate-activated protein kinase (AMPK) is a marker of tissue energy deprivation, which may occur in IR. HYPOTHESIS/OBJECTIVES: To characterize tissue AMPK regulation in ponies subjected to a dietary carbohydrate (CHO) challenge. ANIMALS: Twenty-two mixed-breed ponies. METHODS: Immunohistochemistry and immunoblotting for total AMPK and phospho(P)-AMPK and RT-qPCR for AMPK-responsive genes were performed on laminar, liver, and skeletal muscle samples collected after a 7-day feeding protocol in which ponies stratified on body condition score (BCS; obese or lean) were fed either a low-CHO diet (ESC + starch, approximately 7% DM; n = 5 obese, 5 lean) or a high-CHO diet (ESC + starch, approximately 42% DM; n = 6 obese, 6 lean). RESULTS: 5'-Adenosine-monophosphate-activated protein kinase was immunolocalized to laminar keratinocytes, dermal constituents, and hepatocytes. A high-CHO diet resulted in significantly decreased laminar [P-AMPK] in lean ponies (P = .03), but no changes in skeletal muscle (lean, P = .33; obese, P = .43) or liver (lean, P = .84; obese, P = .13) [P-AMPK]. An inverse correlation existed between [blood glucose] and laminar [P-AMPK] in obese ponies on a high-CHO diet. CONCLUSIONS AND CLINICAL IMPORTANCE: Laminar tissue exhibited a normal response to a high-CHO diet (decreased [P-AMPK]), whereas this response was not observed in liver and skeletal muscle in both lean (skeletal muscle, P = .33; liver, P = .84) and obese (skeletal muscle, P = .43; liver, P = .13) ponies.

A field evaluation of a footbathing solution for the control of digital dermatitis in cattle.

Footbathing is one of the most commonly used methods for controlling digital dermatitis (DD). A farm-based trial was undertaken using six dairy herds involving over 600 cubicle-housed Holstein-Friesian cattle. Split footbaths (length 2.2m) were used to compare the efficacy of two dips, namely, a positive control (5% copper sulphate) and a non-heavy metal-based proprietary dip. The dips were used from early January 2009 for a minimum of 103 days, bathing twice a day for 3 consecutive days every week, using one footbath (three herds) or two in line (three herds). The lesions of DD on the hind feet of cattle were scored by borescope while the animals were being milked, on three occasions (at approximately days 0, 55 and 110) and then compared both directly and by calculating the change in severity from the previous examination (when possible). Data from the 408 cows that had their feet examined for lesions on all three occasions were analysed separately. A reduction in lesion score was seen for both footbath products, but feet bathed in 5% copper sulphate improved more (OR=1.6, CI: 1.14-2.32; P<0.01), and, irrespective of solution, there was a significantly greater improvement in those herds where two footbaths were used (OR=3.39, CI: 2.07-5.19; P<0.001). Lesion improvement over time also increased with lactation number (OR=1.13, CI: 1.02-1.25; P<0.05).

Effectiveness of different regimens of a collective topical treatment using a solution of copper and zinc chelates in the cure of digital dermatitis in dairy farms under field conditions.

A controlled field trial was conducted to evaluate in dairy cattle the benefit provided by different regimens of a collective topical treatment using a solution of copper and zinc chelates to cure digital dermatitis (DD) compared with individual treatment alone, and further to investigate factors that could explain variations in the clinical cure of DD lesions over 6 mo. The study was conducted between November 2009 and October 2010 and involved 4,677 dairy cows from 52 French dairy farms on which DD was endemic. The farms were quasi-randomly allocated to 1 of 4 treatment regimens for 6 mo: no collective treatment (control), walk-through footbath during 4 consecutive milkings every 4 wk (FB/4W) or every 2 wk (FB/2W) and collective spraying during 2 milkings every 2 wk (CS/2W). For ethical and welfare reasons, all farmers also had to treat all detected active DD lesions with individual topical spraying of oxytetracycline. Digital dermatitis and leg hygiene were scored on all lactating cows during milking 7 times every 4 wk by 14 trained investigators. During these farm visits, data related to farm management were also collected. The curative effectiveness of collective treatments was assessed through a Cox survival frailty model as the probability of cure of an active DD lesion during at least 2 consecutive visits. The model was adjusted for farm and cow risk factors as well as initial DD prevalence. Monthly DD cure rates were 58, 55, 76, and 76% in the control, FB/4W, FB/2W, and CS/2W regimens, respectively. The spontaneous monthly cure rate for untreated active DD lesions was 61%. Hazard of cure of DD was increased by 1.28 and 1.41 when walk-through footbath and collective spraying, respectively, were applied over 2 d every 2 wk compared with the control regimen. Applying a walk-through footbath 2 d every 4 wk was not sufficient to improve the cure of DD compared with individual treatments alone. Three main factors were identified as speeding DD healing: cleanliness of the feet, initial small size of the DD lesion, and additional individual topical treatment. Grazing tended to speed DD healing. These results highlight the need of combining several control measures, including individual and collective topical treatments, and improving foot hygiene and the early detection of DD lesions to ensure a high cure rate and rapid curing of digital dermatitis on endemically affected farms.

Effectiveness of different footbathing frequencies using copper sulfate in the control of digital dermatitis in dairy cows.

Two experiments were conducted to test the effectiveness of different footbathing frequencies using CuSO4 in the control of digital dermatitis (DD) in groups of dairy cows with low and high DD prevalence in an endemically infected herd. During the study, groups of cows walked through allocated footbath solutions after milking on 4 consecutive milkings each week, 2 wk, or monthly, depending on treatment. The footbath solutions were changed either after 200 cows had passed through the footbath or within 24 h. All cows were scored weekly during milking for DD lesion stage on the hind feet using a 5-point nominal scale. A transition grade was assigned based on whether the DD lesions improved (1) or deteriorated or did not improve (0) from week to week, and was averaged for all cows in the group. Furthermore, from the longitudinal study data, all transitions between different DD lesion stages between the different time points were used in a discrete, first-order Markov chain (state transition matrix) model. In experiment 1, 70 Holstein-Friesian cows with DD lesions present on at least one of their hind feet were allocated to 1 of 2 footbath treatments for 14 wk: (1) 5% CuSO4 each week or (2) 5% CuSO4 every 2 wk. At the end of the study, no active DD lesions were observed in cows in either treatment group, but significantly more cows had no DD lesions (0.48 ± 0.097 vs. 0.24 ± 0.094) and fewer cows had lesions in the healing stage (0.52 ± 0.104 vs. 0.77 ± 0.090) for the weekly compared with the 2-wk footbathing regimen. The number of active DD lesions that the transition matrix model predicted over time was 3 and 8% for weekly and every 2 wk footbathing treatments, respectively. In experiment 2, 64 cows with no DD lesions on either of their hind feet were allocated to 1 of 2 footbath treatment regimens for 14 wk: (1) 5% CuSO4 every 2 wk or (2) 5% CuSO4 each month. At the end of the trial, significantly more cows had no DD (0.80 ± 0.088 vs. 0.65 ± 0.102) and fewer cows had DD lesions in the healing stage (0.20 ± 0.088 vs. 0.35 ± 0.102) in the every 2 wk regimen than in the monthly footbathing regimen. The number of active DD lesions that the transition matrix model predicted over time was low for both footbathing interventions (1 and 4%, respectively). Increasing the interval between footbaths does not appear the most appropriate mechanism for reducing CuSO4 usage.

Hydration and N-acetyl-l-cysteine alter the microstructure of human nail and bovine hoof: implications for drug delivery.

This work aimed to (a) characterize the microstructure and porosity of human nail and bovine hoof by mercury intrusion porosimetry and SEM image analysis, (b) study the effects of hydration and of N-acetyl-l-cysteine treatment on the microstructure of both membranes, and (c) determine whether the microstructural modifications were associated with changes in drug penetration measured by standard diffusion studies. Bovine hoof surface is more porous than nail surface although there were no differences between the mean surface pore sizes. Hydration and N-acetyl-l-cysteine increased the roughness and apparent surface porosity, and the porosity determined by mercury intrusion porosimetry of both membranes. Pore-Cor™ was used to generate tridimensional structures having percolation characteristics comparable to nail and hooves. The modeled structures were horizontally banded having an inner less-porous area which disappeared upon treatment. Treatment increased the predicted permeability of the simulated structures. Triamcinolone permeation increased significantly for hooves treated N-acetyl-l-cysteine, i.e., the membranes for which microstructural and permeability changes were the largest. Thus, microstructural changes determined via mercury intrusion porosimetry and subsequently modeled by Pore-Cor™ were related to drug diffusion. Further refinement of the technique will allow fast screening of penetration enhancers to be used in ungual drug delivery.

Curative effect of topical treatment of digital dermatitis with a gel containing activated copper and zinc chelate.

The efficacy of two topical treatments for painful ulcerative stage (M2) of bovine digital dermatitis (BDD) lesions was compared in a clinical trial conducted on five dairy farms in 2009 to 2010. The first treatment was a water-based gel with active components copper and zinc (Intra Hoof-fit gel [IHF]) and the second treatment was a topical chlortetracycline spray (CTC spray). The experimental unit for this study was the hindleg with the presence of a BDD lesion. Cure was defined as the transition of an M2 lesion into a healed (M0) or a non-painful chronic stage (M4) of BDD at D28. On day 0, cows with M2 BDD lesions were photographed and were treated with either IHF or CTC. Subsequently, feet were photographed and scored on D28. The cure rate of M2 BDD lesions treated with IHF at D28 was 0.92 (CI 0.84 to 0.96) and was significantly better than for M2 BDD lesions treated with CTC, which was 0.58 (CI 0.47 to 0.68).

Lamellar leukocyte infiltration and involvement of IL-6 during oligofructose-induced equine laminitis development.

Laminitis is known to involve deregulation of proteases and destruction of the lamellar basement membrane with the host inflammatory response also playing a role. Leukocyte infiltration has been well characterized in the black walnut model of laminitis induction, but not in carbohydrate induced models. Increased gene expression of multiple cytokines, including IL-6, has also been implicated in laminitis development. Using real time PCR, immunohistochemistry and zymography methods, we characterize leukocyte infiltration and IL-6 gene expression in oligofructose (OF) induced laminitis. As well, we use two in vitro models to investigate a role for IL-6 in protease regulation. Laminitis was induced in normal standardbred horses (n=5) by alimentary OF dosing and lamellar biopsies were obtained throughout the 48 h experimental period. Lamellar explants and keratinocytes were also isolated from clinically normal horses for in vitro experiments. We found infiltration of calprotectin-positive leukocytes (monocytes and neutrophils) at 18-24h post oligofructose dosing, while IL-6 gene expression was increased as early as 12h post dosing. Additionally, while we found that IL-6 did not cause significant BM damage in vitro, it did result in increased secreted proMMP-9 levels from lamellar explants. Thus, we find that leukocyte infiltration does occur during oligofructose-induced laminitis development, however, IL-6 gene expression in the lamellae may precede leukocyte infiltration. Additionally, we show IL-6 plays a role in increasing the level of proMMP-9 in vivo in a manner that does not involve keratinocytes.

Effects of topical nitroglycerine patches and ointment on digital venous plasma nitric oxide concentrations and digital blood flow in healthy conscious horses.

OBJECTIVE: To measure and compare palmar digital venous plasma nitric oxide (NO) concentrations and digital arterial blood flow after application of topical nitroglycerine (NTG). STUDY DESIGN: Experimental study. ANIMALS: Healthy adult horses (n=8). METHODS: Digital blood flow was measured by an ultrasonic Doppler flow probe surgically implanted around the medial palmar digital artery. Blood was collected from a catheter placed in the medial palmar digital vein for quantification of NO. NTG patches, NTG ointment or control patches were placed over the palmar digital vessels at the level of the fetlock. Two horses had an intra-arterial infusion of an NTG solution into the medial palmar digital artery in a pilot study. RESULTS: Digital arterial blood flow did not change significantly with application of the NTG patches, NTG ointment, or control patches. There were no statistically significant or biologically important changes in digital venous NO concentrations across time or between treated and control horses. In the pilot study, digital arterial blood flow and palmar digital venous NO concentrations increased with intra-arterial infusion of NTG. CONCLUSIONS: In clinically healthy horses, digital arterial blood flow and digital venous plasma NO concentrations did not change significantly with application of the NTG patches/ointment. These treatments are unlikely to have an effect on the digital vasculature of laminitic horses, however, further investigation is warranted. CLINICAL RELEVANCE: Although NTG patches have been used as a method of decreasing vasomotor tone and improving digital blood flow in horses with laminitis, this study provides evidence in healthy conscious horses that this treatment is not effective in altering digital blood flow.

Submural histopathologic changes attributable to peracute laminitis in horses.

OBJECTIVE: To describe submural histopathologic changes attributable to peracute laminitis in horses. ANIMALS: 20 adult horses. PROCEDURE: A concurrent-control design was used to compare laminar lesions in 10 horses subjected to carbohydrate-induced laminitis with laminar characteristics of 10 sex- and aged-matched control horses with normal feet. Horses in the treatment group were administered an overload of carbohydrate. Tissues were obtained by biopsy 4 to 8 hours after onset of lameness or 72 hours after administration of the carbohydrate overload when lameness did not develop. Sections were stained with H&E, Masson's trichrome, and periodic acid-Schiff stains. Histopathologic changes were analyzed to detect differences between groups and to correlate epidermal changes with severity and duration of lameness. RESULTS: Analysis indicated that dermal and epidermal lesions were evident despite lack of visible separation of the epidermal basement membrane, can be found in horses without detectable lameness, and were nonspecific and progressive following onset of lameness. Furthermore, severity and location of lesions were associated with severity and duration of lameness. CONCLUSION AND CLINICAL RELEVANCE: These observations are consistent with the concept that separation of the laminar epithelial basement membrane is a delayed step in the pathogenesis of acute laminitis, digital vascular hypoperfusion is an underlying cause for laminitis, and the potential for repeated episodes of subclinical laminitis may underlie the development of structural and mechanical changes consistent with chronic laminitis despite lack of clinical signs of acute laminitis.

Effect of dietary selenium source, level, and pig hair color on various selenium indices.

The first experiment evaluated the effects of feeding various levels of Se, two Se sources, and hair color on selenosis responses in growing-finishing pigs. The study conducted in two replicates was a 2 x 6 x 2 factorial arrangement in a split-plot design. Sodium selenite and Se-enriched yeast added at 0.3, 1, 3, 5, 7, and 10 ppm Se served as the main plot and pig hair color as the subplot. A total of 96 crossbred pigs were allotted and fed their treatment diets for a 12-wk period. White and dark (red or black) hair samples were collected from the dorsal-midline at the 4-, 8-, and 12-wk periods from one pig of each hair color from each treatment pen. Lower pig weights (P < 0.10) and daily gains (P < 0.05) occurred as dietary Se level increased when pigs were fed either Se source. Selenosis responses were somewhat more severe, when the inorganic Se source was fed. Alopecia and hoof separation were encountered after the 8-wk period when pigs were fed inorganic rather than organic Se. Plasma Se increased as dietary level increased (P < 0.01), when organic Se was provided (P < 0.01), and was higher (P < 0.05) when pigs were white-haired. A time x hair color x dietary Se level interaction (P < 0.05) occurred, in which hair Se concentration was higher in dark- than in white-colored pigs and increased as dietary Se level increased as the experiment progressed. The correlation coefficient between dietary Se level and hair Se concentration averaged 0.90 (P < 0.01). Cysteine was the amino acid in the highest concentration in hair, but this and other amino acids were not affected by Se level, Se source, or hair color. A second experiment was a 3 x 6 factorial arrangement in a split-plot design with three 9-mo-old gilts from each of the Yorkshire, Duroc, and Hampshire breeds to determine whether hair Se concentration differed by body location and breed. Hair samples were collected from the shoulder, back, rump, front-leg, belly, and hind-leg areas. Hair Se concentration was higher in red- and white-haired pigs and lower in black-haired gilts (P < 0.01). Higher hair Se concentrations (P < 0.05) occurred from the lower than from the upper body areas. Our results suggest that selenosis occurs at dietary levels > 5 ppm and that white-haired pigs exhibit alopecia sooner than dark-haired pigs. No difference in hair Se concentration occurred when diets were < 1 ppm Se, but as dietary Se level increased dark-haired pigs retained more Se in their hair than white-haired pigs.

Effect of a supplementary dietary evening primrose oil mixture on hoof growth, hoof growth rate and hoof lipid fractions in horses: a controlled and blinded trial.

The lipid chemistry of the normal equine hoof, together with the effect of oral supplementation with an evening primrose oil mixture (EPOM) on its growth, growth rate and lipid content was assessed in a controlled and blinded feeding trial at the Defence Animal Centre. Twelve horses were paired as closely as possible according to sex, age, weight, height and colour and then one from each pair was randomly allocated to treatment or control groups. The treatment group received 30 ml of oral EPOM/day, otherwise the nutrition and management regimes were the same for all horses. No significant differences (P > 0.05) were seen between treatment and control groups for hoof horn growth or growth rate. However, there was a significant difference (P < 0.05) in hoof horn growth within the treatment group only between weeks 4 and 8 after the start of supplementation. The stratum medium contained significantly higher amounts of cholesterol ester (P < 0.05), triglycerides (P < 0.001) and free fatty acids (P < 0.05) than the periople. The periople contained significantly higher levels of free cholesterol and phospholipid (P < 0.001) than the stratum medium of the hoof wall. There were no significant differences (P > 0.05) between treatment and control groups for any of the lipid fractions measured for the stratum medium from the clippings of the hoof wall. However, there were differences in perioplic lipid analysis with significant increases (P < 0.05) in cholesterol esters and partial glycerides and a significant reduction (P < 0.001) in free cholesterol in the treatment group following supplementation.

Pathology of experimentally induced chronic selenosis (alkali disease) in yearling cattle.

Prolonged oral exposure of cattle to elevated dietary selenium (Se) in forage and seleniferous plants in seleniferous areas of the western United States is associated historically with 2 clinical syndromes: alkali disease and "blind staggers." The potential for Se-induced disease in cattle and other species is considerable in areas with seleniferous shales, Se-accumulating plants, arid climates, and alkaline soils. These 2 Se-associated conditions were defined in the 1930s and 1940s, and the nosology of blind staggers is questionable. Seventeen yearling steers fed 0.15, 0.28, and 0.8 mg Se/kg body weight as selenomethionine or selenite for 120 days were euthanized and examined postmortem. Significant lesions were confined to 4 steers in the medium- and high-dose selenomethionine group and to 1 steer in the high-dose selenite group. Grossly, dystrophic hoof lesions developed in 2 steers, 1 of which had extensive separation of horn from lamellar and coronary epidermis and also lost hair from the tail switch. Histologically, tubules in the stratum medium of hooves from these 5 steers were replaced by islands of parakeratotic cellular debris, separated by more normal hoof matrix. Two of the 5 steers also had hyperplasia, acanthosis, parakeratosis, and disorganized germinal epithelium of varying severity in hoof epithelium, particularly at the tips of epidermal lamellae. These changes may distinguish the hoof lesions of chronic selenosis from those of chronic laminitis in cattle, in which dermal (chorial) changes predominate. In skin from the distal part of the tail of the animal that lost its switch, most follicles were atrophic and devoid of hairshafts and displayed dyskeratosis and mild superficial follicular keratosis. No significant lesions developed in tissues other than integument. Autometallographic staining for catalytic Se bonds in various tissues, including skin, liver, and kidney, revealed no positive staining of hair shafts; the correlation between stain intensity and dose group was poor. These findings indicate that dietary exposure for 4 months to 0.28 and 0.8 mg Se/kg in the form of selenomethionine and to 0.8 mg Se/kg in the form of sodium selenite reproduces in some cattle mild (subclinical) to severe (clinical) forms of alkali disease. No significant neurological, renal, or hepatic lesions developed, supporting the contention that blind staggers is caused by factors other than excessive dietary selenium.

Symmetrical lupoid onychodystrophy in dogs: a retrospective analysis of 18 cases (1989-1993).

A unique, symmetrical onychodystrophy is described in 18 dogs. A rather sudden onset of onychomadesis is followed by chronic onychodystrophy affecting all claws. Pain and lameness are recognized in half of the patients, but the dogs are healthy otherwise. Histopathologically, this disorder is characterized by hydropic and lichenoid interface dermatitis. Nine dogs were treated with a commercial, fatty-acid supplement and had good-to-excellent responses. Due to the clinicopathological characteristics of this disorder, the authors propose the name "symmetrical lupoid onychodystrophy."

Effect of photoperiod, testosterone, and estradiol on body mass, bifid claw size, and pelage color in collared lemmings (Dicrostonyx groenlandicus).

Collared lemmings undergo several photoperiod-mediated seasonal physiological changes. When exposed to short photoperiod, lemmings increase in size, develop a bifid claw, and molt to a white pelage. Previous data indicate that body mass, claw size, and pelage color are influenced by hormones of testicular origin, suggesting that, on a seasonal basis, changes in production of, or sensitivity to, testicular hormones may play a role in the development of the phenotype characteristic of the ambient photoperiod. The present study was designed to determine if the active testicular hormone(s) is testosterone (T) and/or estradiol (E2) and if seasonally changing physiological traits in female lemmings are also influenced by gonadal status. Fifty-day-old lemmings, reared in 22L:2D (long day), 16L:8D (intermediate day), or 8L:16D (short day), were either gonadectomized or sham operated and given either empty Silastic implants or implants containing T (4 or 10 mm; castrated males), E2 (4 mm undiluted or diluted 1:4 with cholesterol; ovariectomized females), the aromatase inhibitor ATD (androsta-1,4,6-triene-3,17-dione; 2 x 20 mm; intact animals of both sexes), or ATD plus a 10-mm T implant (castrated males). After a 6-week treatment period, changes in body mass, bifid claw width, pelage color stage, and serum prolactin (PRL) were assessed. The effects of gonadectomy and steroid treatment depended upon photoperiod. Whereas gonadectomy increased mass gained by both sexes under intermediate and short day, under long day only females showed the positive mass response to gonadectomy. Treatment with T and E2 reversed the effect of gonadectomy on body mass under intermediate day and decreased the amount of mass gained under short day. Treatment with ATD (males) and E2 (females) indicated that E2 was the hormone responsible for the tonic, inhibitory effect of the gonads on body mass in both sexes. Claw size was most sensitive to steroid manipulation in animals housed in long day, in which all treatments had a negative influence. Gonadectomy under short day resulted in the development of a whiter pelage in both sexes. The effect of gonadectomy on pelage in female lemmings, and its reversal by E2 treatment, may have been partially due to alteration of serum PRL.

Effect of methionine hydroxy analog supplementation on dairy cattle hoof growth and composition.

Fifty lactating Holstein cows were assigned randomly to one of two treatments, control and control plus approximately 30 g methionine hydroxy analog, and confined on concrete for 11 mo. The control diet consisted of sorghum silage and concentrate fed as a blended ration. Sulfur contents of dry matter were .12% and .16% for control and methionine hydroxy analog rations. Hoof growth and hardness were measured on front and rear right abaxial claws in the dorsal and lateral regions. Hoof growth rates were measured for four periods; summer-fall, fall-winter, winter-spring, and spring-summer, each 70 to 90 days. Hooves of cows fed methionine hydroxy analog grew faster than those of control cows during spring-summer in all regions. Variations of growth rates of hooves were seasonal and tended to follow variations in daily photoperiod. Wear rates were not affected significantly by treatment. Hooves of cows fed methionine hydroxy analog were softer in the top dorsal region at the end of winter-spring and in the dorsal toe region at the end of spring-summer. All other locations were not affected significantly by treatment. The toe region was harder than the top of the hoof. Cows fed methionine hydroxy analog had less cysteine and proline in hoof than control cows and greater percentages of methionine lysine, tyrosine, and glutamic acid. These results suggest that a decrease of disulfide bonding occurred in the hoof tissue of cows fed methionine hydroxy analog. Cows fed methionine hydroxy analog produced more actual milk, milk fat, and 4% fat-corrected milk during 180 days than did control cows.