Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
Bila CG, Perreira CL, Gruys E.Horses on several farms in Mozambique were inadvertently fed with a concentrate containing 69 ppm monensin. The horses developed acute signs of toxicity and several died. The animals were depressed, anorectic and paretic before death. Epistaxis was observed in 1 case. Petechial haemorrhages were present in the muscles, heart, lungs, gastrointestinal tract and spleen in 3 horses necropsied. No significant histopathological cardiac and skeletal muscle lesions were seen, except in 1 case, in which there was focal loss of myofibrils.
Borges LM, Oliveira PR, Lisboa CL, Ribeiro MF.The objective of this study was to investigate some aspects of horse resistance to natural infestations of Anocentor nitens and Amblyomma cajennense over a 2-year period. Free-living stages of A. nitens were used to evaluate the influence of season of the year on horse resistance. Every 2 weeks, 10 selected engorged females, weighing 150-329 mg, were removed from naturally infested horses and were individually placed into glass tubes closed with a cotton stopper, and maintained in an incubator. The biological parameters evaluated varied according to the season of the year, i.e., reproductive e...
Nie GJ, Wenzel JG, Johnson KE.An artificial insemination dose for mares consisting of 500 million progressively motile spermatozoa is considered "standard" by most clinicians. However, little information is available directly comparing pregnancy outcome among methods of evaluating and selecting spermatozoa for insemination. The objective of this study was to determine if the method of spermatozoal evaluation and selection influences fertility as measured by pregnancy outcome. Mares were inseminated with 100 or 500 million spermatozoa that were selected for progressive motility, normal morphology, hypoosmotic swelling or ab...
Ellison SP, Omara-Opyene AL, Yowell CA, Marsh AE, Dame JB.A gene encoding a major 29 kDa surface antigen from Sarcocystis neurona, the primary causative agent of equine protozoal myeloencephalitis (EPM), was cloned, sequenced, and expressed as a recombinant protein. A cDNA library was prepared in the expression vector lambda ZAP from polyA+mRNA isolated from S. neurona merozoites cultivated in vitro. Random sequencing of 96 clones identified a clone of an abundant transcript having a translated amino acid sequence with 30% identity to the 31-kDa surface antigen of Sarcocystis muris cyst merozoites. Southern blot analysis indicated that the correspond...
Gehring R.The Veterinary Pharmacovigilance Centre received 59 reports of suspected adverse drug reactions during the period January 1998 - February 2001. The number of reports received increased after the establishment of a formal procedure for recording and responding to reports. The number of reports received per species was: dogs 19, cats 15, cattle 7, sheep/ goats 6, chickens 4, pigs 3, horses 2 and giraffe 1. Many different types of adverse reactions were reported, including lack of efficacy, hypersensitivity, inappropriate use of products by non-veterinarians, known adverse effects and adverse eff...
Bell NJ, Thomas S.An aged female donkey developed a severe, localised, suppurative panniculitis secondary to a skin wound. Bacterial culture of swabs taken from the wound gave a profuse growth of multi-drug-resistant Pseudomonas aeruginosa, a profuse growth of Escherichia coli and a moderate growth of beta-haemolytic Streptococcus species. The lesion did not respond to conventional medical and surgical treatment and continued to progress. Six applications of sterile larvae (maggots) of the common greenbottle, Lucilia sericata, were used to debride the wound successfully.
Tryland M.In December 1801, the first vaccination against smallpox in Norway took place. Vaccine material came from Denmark, England, Ireland, and other countries; it was also obtained from a few local cowpox cases. What mattered was the effect, not the origin. Several reports indicate that variola virus itself, the cause of smallpox, was also used for human vaccination after passages through cows and horses. A vaccine institute for production of vaccine in calves was established in Kristiania in 1891. Cowpox was once a rare disease in cattle, but a total of 70,985 bovine cases were reported between 188...
Hagen SJ, Latypov RF, Dolgikh DA, Roder H.Time-resolved spectroscopic studies of unfolded horse iron(II) cytochrome c have suggested that the imidazole side chains of His26 and His33 bind transiently to the heme iron on microsecond time scales, after photodissociation of a carbon monoxide ligand from the heme. Our studies of four variants of cytochrome c (horse wild type, horse H33N, horse H33N/H26Q, and tuna wild type), unfolded in guanidine hydrochloride at pH 6.5, demonstrate that these side chains are responsible for the observed microsecond spectral changes. As His33 and then His26 are eliminated from the horse wild-type sequence...
Popot MA, Bobin S, Bonnaire Y, Delahaut PH, Closset J.Insulin-like growth factor-I (IGF -I) is likely to be an indicator of somatotropin (ST) administration in the horse. To investigate the different ways ST administration may be detected, the following aspects of IGF -I concentrations in plasma were studied: (i) the daily variation; (ii) variation following a treadmill test; (iii) concentrations at rest and after exercise; and (iv) concentrations in plasma from two young horses and two adults treated with methionyl equine somatotropin (e ST). In the population of horses at rest, IGF -I mean concentration (SEM) was 261 (104) ng ml(-1). In post ra...
Tamzali Y, Guelfi JF, Braun JP.Plasma fibrinogen is widely used in horse practice as an unspecific positive marker of inflammatory diseases; it is also lowered in disseminated intravascular coagulation. Three fibrinogen measurement methods--Millar's heat-denaturation in a microhaematocrit tube, automated reader for heat-denaturation, and chronometric measurement of clot formation after addition of excess thrombin-were compared by means of Passing-Bablock's regression and Bland-Altman difference plots, in blood plasma of 30 clinically healthy and 57 diseased horses. Correlations between the three techniques were excellent (r...
Machida N, Tanaka Y, Taya K, Nakamura T.A case of congenital ovarian interstitial cell hamartoma in a thoroughbred foal that died of apparent nutritional myopathy (white-muscle disease) 14 h after birth is described. An incidental finding at necropsy was a pale brown, mushroom-shaped, pedunculated mass (6 x 4 x 3 cm) attached to the left ovary. On the cut surface, the mass had a peripheral rim of dense parenchyma (3-5 mm wide), surrounding a pale gelatinous core. Histologically, the mass consisted of a peripheral zone of densely packed large cells that were quite similar, morphologically, to fetal ovarian interstitial cells, and a c...
Viitanen M, Bird J, Makela O, Schramme M, Smith R, Tulamo RM, May S.The purpose of this study was to investigate biochemical changes in synovial fluid in navicular disease, and to establish if synovial fluid from the distal interphalangeal joint (DIP) could be used diagnostically to assess alterations in the synovial fluid of the navicular bursa. Cartilage oligomeric matrix protein (COMP), total glycosaminoglycans (GAG), hyaluronan (HA), metalloproteinases 2 and -9 (MMP-2 and MMP-9) and total protein (TP) levels were determined in synovial fluids obtained from 18 navicular bursae and 35 DIP -joints from animals suffering from navicular disease, and the same sy...
Hatanaka H, Iourin O, Rao Z, Fry E, Kingsman A, Stuart DI.The Gag polyprotein is key to the budding of retroviruses from host cells and is cleaved upon virion maturation, the N-terminal membrane-binding domain forming the matrix protein (MA). The 2.8-A resolution crystal structure of MA of equine infectious anemia virus (EIAV), a lentivirus, reveals that, despite showing no sequence similarity, more than half of the molecule can be superimposed on the MAs of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV). However, unlike the structures formed by HIV-1 and SIV MAs, the oligomerization state observed is not trimeric...
Jeannotte ME, Slavić D, Frey J, Kuhnert P, MacInnes JI.Twenty-four Actinobacillus suis isolates obtained from several species of non-porcine mammals were compared to the representative porcine strains, ATCC 15557 (serotype O1) and H89-1173 (serotype O2), by O serotyping, DNA fingerprinting, PCR amplification of apxICA, apxIICA and apxIIICA toxin genes and by rrs (16S rRNA) gene sequencing. Only two strains, both equine, reacted with O1 antiserum while two others, one canine and the other feline, reacted with O2 antiserum. One equine strain reacted weakly with both antisera. No amplification of apx genes was found with the non-porcine O1 or the "no...
Yildirim AO, Lämmler Ch, Weiss R.Seven group B streptococcal cultures isolated from three horses reacted with group B-specific antiserum, were CAMP positive, pigmented and showed the typical biochemical properties of Streptococcus agalactiae. The identification could be confirmed by PCR amplification of the 16S rRNA gene and a subsequent RsaI restriction pattern typical for S. agalactiae. In addition, the isolates were identified by amplification of species specific parts of the 16S rRNA gene, the 16S-23S rRNA intergenic spacer region and by amplification of the CAMP-factor (cfb) gene. Six isolates could be classified as sero...
Simpson CM, Lumsden JM.A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed laterome...
Ito M, Itou T, Sakai T, Santos MF, Arai YT, Takasaki T, Kurane I, Ito FH.Brain samples from different animal species including humans: five vampire bats, 14 cattle, 12 dogs, 11 cats, two horses, one pig, one sheep and three humans collected from various geographical regions of Brazil were found to be positive for rabies by means of the fluorescent antibody test (FAT) and the mouse inoculation test (MIT). The brain samples were retested for rabies by means of the reverse transcription and polymerase chain reaction (RT-PCR) with 2 primer sets (P1/P2 and RHNI/RHNS3), which amplified full or partial regions on the nucleoprotein (N) gene of the rabies virus, respectivel...
Ito S, Hobo S, Eto D, Sato H.To evaluate a hypothese that use of bronchoalveolar lavage (BAL) for early treatment of pneumonia would improve their prognosis by reducing bacterial numbers and excessive numbers of neutrophils in the lung, initial experiences with BAL in the diagnosis and treatment of pneumonia were performed in 36 racehorses that became ill within 24 hr of long distance travel (1,200-1,600 km, 26-32 hr) by road. Comparisons were made of the outcomes of the 36 horses and those of 42 horses (81.0% recovered, 50.0% returned to racing) treated for transport associated pneumonia without BAL. The total amount of ...
Ohmura H, Hiraga A, Aida H, Kuwahara M, Tsubone H.To investigate the effects of repeated atropine injection on heart rate (HR) variability in resting Thoroughbred horses, two microg/ kg of atropine as parasympathetic nervous blockade was injected intravenously every 6 min to a total of 8 microg/kg after intravenous administration of 0.2 mg/kg of propranolol as sympathetic nervous blockade. We recorded electrocardiograms and obtained the HR, then evaluated variation in HR from the power spectrum in terms of low frequency (LF, 0.01-0.07 Hz) power and high frequency (HF, 0.07-0.6 Hz) power. Administration of atropine decreased parasympathetic ne...
Hudson NP, Mayhew IG, Pearson GT.Intracellular microelectrode recordings were made from smooth muscle cells in cross-sectional preparations of equine ileum, superfused in vitro. Membrane potential oscillations and spike potentials were recorded in all preparations, but recordings were made more readily from cells in the longitudinal muscle layer than from cells in the circular layer. The mean (se) resting membrane potential (RMP) of smooth muscle cells in the longitudinal muscle layer was -51.9 (1.2) mV, and the membrane potential oscillations in this layer had a mean amplitude of 4.8 (0.4) mV, a frequency of 9.0 (0.1) cycles...
Figueras F, Castelo-Branco C, Pons F, Sanjuán A, Vanrell JA.The aim of the present study was to determine whether assignment to continuous estrogen-progestin therapy is more effective in protecting against bone loss than assignment to a sequential regimen. Methods: A total of 104 postmenopausal women were randomly assigned to one of two groups of treatment, Conjugated Equine Estrogens and Medroxyprogestin without interruption (continuous group) and Conjugated Equine Estrogens over 25 days with Medroxyprogestin beyond the 14th day (sequential group). Bone mineral density (BMD) was measured at inclusion, 12 and 24 months later by dual energy X-ray absorp...
Rols MP, Tamzali Y, Teissié J.Sarcoids are skin spontaneous tumours detected in horses. It can be cured by chemotherapy by using cisplatin. A multisequence treatment must be performed. Problems are present due to the poor diffusion of the hydrophilic product in the tumours. Electropulsation is known to drastically enhance the effect of antitumoral drugs in vivo. Taking into account the very successful results of the group in Ljubljana (Slovenia), we started a research clinical program where electropulsation was applied after local cisplatin injection. The size of sarcoids is large (several centimeters). A specially designe...
Meehan M, Kelly SM, Price NC, Owen P.The major cell wall-associated protein of the equine pathogen Streptococcus equi subsp. equi is a fibrinogen-binding protein (FgBP) which binds horse fibrinogen and equine IgG-Fc avidly through residues located in the N-terminal half and central regions of the molecule, respectively. The molecule is a major virulence factor for the organism and displays protective potential. In the present study, we use circular dichroism spectroscopy to investigate the secondary structure of the protein and show through the analysis of a panel of recombinant FgBP truncates that the C-terminal portion of FgBP ...
Uzun M, Karkhan A, Kopar A.Analysis of the blood protein system was used to study the genetic composition of Arabian horses. Biochemical markers of eight polymorphic loci (Tf, Al, Es, AlB, Gc, Hb, PGD, and PGM) were electrophoretically identified in blood samples. A total of 43 phenotypes were identified for these polymorphic systems. The Tf, Hb, and Es loci appeared to be more polymorphic than the other loci studied. Statistically significant differences between the observed and expected genotypic frequencies were found for the PGD and PGM loci (P < 0.05 and P < 0.01, respectively). Individual allele frequencies,...
Sod GA, Riggs LM, Mitchell CF, Martin GS.To compare in vitro monotonic biomechanical properties of an axial 3-hole, 4.5 mm narrow locking compression plate (ELCP) using 5.0 mm locking screws and 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (ELCP-TLS) with an axial 3-hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP-TLS) for equine proximal interphalangeal (PIP) joint arthrodesis. Methods: Experimental. Methods: Cadaveric adult equine forel...
Esser AF, Tarnuzzer RW, Tomlinson S, Tatar LD, Stanley KK.Lack of hemolytic activity of horse serum is an inherent property of horse C9. To understand the molecular reasons for this deficiency we have cloned C9 cDNA from a horse liver cDNA library and have sequenced the cDNA yielding the complete coding sequence for horse C9. Purification of C9 from horse plasma and microsequencing established the N-terminus of the mature protein and verified that the correct horse C9 cDNA clone had been isolated. The deduced amino acid sequence corresponds to a mature protein of 526 amino acids that is 77% identical to human C9. It has the same domain structure as h...
Kern JR, Cardellina JH.Anemonin, the dilactone of cyclobutane-1,2-diol-1,2-diacrylic acid derived from the cyclodimerization of protoanemonin, a known blistering agent, was isolated from Clematis hirsutissima, a plant used by the Nez Perce and Teton Sioux nations as a horse stimulant.
Patton ME, Andrews FM, Bogers SH, Wong D, McKenzie HC, Werre SR, Byron CR.Ileus is a common life-threatening problem in horses, and currently available treatments may be ineffective. The purpose of this study was to determine whether bit chewing, a form of sham feeding, decreases the gastric emptying time (GET), small intestinal transit time (SITT), and total orocecal transit time (OCTT) in clinically normal horses in a prospective crossover study. Nine healthy horses were acclimated and fed a standardized diet. Following 24 h of fasting, self-contained video endoscopy capsules and acetaminophen were administered into the stomach via a nasogastric tube. Each horse u...
Jones I, Madej A.Microtitre plates were coated with antiserum against oestradiol-17 beta-6-(O-carboxymethyl)-oxime bovine serum albumin raised in sheep. The plasma samples (0.2-1.0 ml) were extracted with peroxide-free diethyl ether prepared daily by treatment with Al2O3. The enzyme conjugate was prepared by coupling oestradiol-17 beta-6-(O-carboxymethyl)-oxime to horse-radish peroxidase. The conjugate was chromatographed on a Sephadex G-25 column. The standard curve ranged from 0.37 to 18.40 fmol/well of oestradiol-17 beta. The amount of oestradiol-17 beta causing a 50% reduction of maximum binding was 4.4 fm...
Silver IA, Eisinger M.We have examined the possible regulatory role of epidermal cell extract(s) (ECE) on skin cells, namely fibroblasts and keratinocytes, both in vivo and in vitro with particular reference to modification of scar formation. In an experimental wound model in pigs, it was found that extracts of cultured human and pig keratinocytes stimulated replication of epidermal cells and their migration from wound edges and remnants of hair follicles and sebaceous glands, together with hair growth, but at the same time suppressed fibroblast proliferation in the dermis. Sections of healing skin wounds that had ...
Thieme K, Mesquita L, Lieberth S, Dancker C, Doherr MG, Eule JC.There is limited knowledge regarding the safety and accuracy of ultrasound-guided retrobulbar nerve blocks in horses. The aim of this study was to compare these parameters between blind and ultrasound-guided injection techniques for the dorsal retrobulbar nerve block in horses. Methods: Equine cadaver heads were used to inject the retrobulbar space with contrast medium (CM). Injections were performed either blindly based on anatomic landmarks (blind group, n = 44) or under ultrasonographic guidance (US-group, n = 44), equally divided between an experienced and unexperienced operator. Needl...
Dirks E, de Heus P, Joachim A, Cavalleri JV, Schwendenwein I, Melchert M, Fuehrer HP.A 23-year-old pregnant warmblood mare from Güssing, Eastern Austria, presented with apathy, anemia, fever, tachycardia and tachypnoea, and a severely elevated serum amyloid A concentration. The horse had a poor body condition and showed thoracic and pericardial effusions, and later dependent edema and icteric mucous membranes. Blood smear and molecular analyses revealed an infection with . Upon treatment with imidocarb diproprionate, the mare improved clinically, parasites were undetectable in blood smears, and 19 days after hospitalization the horse was discharged from hospital. However, 89 ...
Elnady FA, Sheta E, Khalifa AK, Rizk H.Endoscopy of the upper respiratory tract (URT) is one of the minimally invasive techniques used for diagnosis and treatment of diseases in horses. Training in the use of an endoscope follows an apprenticeship approach, with extensive practice needed to help achieve effective skills acquisition. The use of live animals for training presents the risk of injury to both the animal and the trainee. The increased number of students and practitioners, a shortage of facilities, and limited time available from expert clinicians add more challenges to the training process. In this work, we focused on th...
Muir WW, Sams RA, Hubbell JA, Hinchcliff KW, Gadawski J.To determine the effects of IV administration of enalaprilat on cardiorespiratory and hematologic variables as well as inhibition of angiotensin converting enzyme (ACE) activity in exercising horses. Methods: 6 adult horses. Methods: Horses were trained by running on a treadmill for 5 weeks. Training was continued throughout the study period, and each horse also ran 2 simulated races at 120% of maximum oxygen consumption. Three horses were randomly selected to receive treatment 1 (saline [0.9% NaCl] solution), and the remaining 3 horses received treatment 2 (enalaprilat; 0.5 mg/kg of body weig...
Bergstrom TC, Sakai RR, Nieto JE.A mare was euthanized because of gastric rupture secondary to complete duodenal obstruction by 2 bezoars located in the pylorus and proximal duodenum. Infrared spectroscopy showed that the bezoars were composed of psyllium. The mare had been receiving treatment with a pelleted psyllium product at 4 times the recommended dosage. Veterinarians should be aware that treatment of colic in horses with pelleted psyllium products could be associated with gastric impaction. Rupture gastrique catastrophique secondaire à des pharmacobézoards de psyllium en boulettes chez un cheval. Une jument a été e...
Sabaté D, Homedes J, Salichs M, Sust M, Monreal L.In horses, it has been demonstrated that suxibuzone (SBZ) has a lower gastric ulcerogenic effect than phenylbutazone (PBZ). However, no field trials have been reported comparing the efficacy of the drugs in alleviating lameness. Objective: To compare the therapeutic effect of SBZ to that of PBZ when administered orally in lame horses. Acceptability of both products was also compared. Methods: Lame horses (n = 155) were used in a multicentre, controlled, randomised and double-blinded clinical trial. Horses were treated orally with either SBZ or PBZ at equivalent therapeutic dosages. PBZ was giv...
Coleman MC, Walzem RL, Kieffer AJ, Minamoto T, Suchodolski J, Cohen ND.Lipoproteins are water-miscible macromolecules enabling the transport of lipids in blood. In humans, altered proportions of lipoproteins are used to detect and classify metabolic diseases. Obesity and obesity-related comorbidities are common in horses. The pathophysiology of obesity is poorly understood and likely multifactorial. Development of new diagnostic tests to identify horses at risk of developing obesity to implement preventative measures is critical; however, a necessary first step to accomplish this goal is to improve our understanding of the pathophysiology of disease. Thus, the ob...
Merriam JG.There is a lot of room for us to become the central source of medical information regarding shoeing and lameness in our own practice area. This takes a good bit of effort and a real "outreach" to client and farrier. It can be done with the one tool we are best at--the acquisition and careful dispensing of information that we can put together regarding the health of the foot. Such information includes the following: 1. Radiographically guided hoof trimming and shoeing. 2. Ultrasonography. 3. Digital radiography. 4. Thermography. 5. Nutritional and health counseling. Become the "local" expert in...
Ababneh M, Ababneh H, Shidaifat F.Phospholipase A2 (PLA2) is a key enzyme for biosynthesis of PGF2α. Real-time RT-PCR and immunohistochemistry were used to determine transcription and cellular distribution of cytosolic PLA2 (cPLA2) in the equine endometrium during the oestrous cycle and early pregnancy. Endometrial biopsy and blood samples were collected from cycling mares on days (d) 8, 11, 15 and 18 (oestrus) (Day 0 = Day of ovulation; n = 5 for each day) and from pregnant mares (n = 4) on d15. Except for mares on d18 and some cyclic mares (n = 2) on d15 with low progesterone (P₄) concentrations (< 3.18 nm), P₄ conce...
Hernández-Vidal G, Jeffcott LB, Davies ME.A polyclonal antiserum raised in sheep against human cathepsin B was tested for specificity and cross-reactivity with the horse homologue by SDS-PAGE and Western blotting, prior to being used for immunolocalization of the enzyme in equine articular cartilage. In Western blots, the antiserum recognized the 30 kDa single chain and 25 kDa heavy chain of the mature enzyme in purified bovine cathepsin B, and corresponding bands at 32 and 27 kDa in equine chondrocyte and fibroblast lysates. This antiserum was then used to compare the expression and distribution of cathepsin B in normal and dyschondr...
Fontes KFLP, Silva-Júnior LC, Nascimento SA, Chaves DP, Pinheiro-Júnior JW, Freitas AC, Castro RS, Jesus ALS.A codon-optimized equine infectious anemia virus p26 gene was fused to a maltose-binding protein (MBP) and expressed in Escherichia coli for use as an antigen in agar gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA) for diagnosis of equine infectious anemia. An analysis of analytical sensitivity and specificity showed that the antigen MBP-p26rec reacted positively with a reference World Organization for Animal Health serum and demonstrated no cross-reaction against sera from vaccinated animals in either test. The diagnostic characteristics were evaluated and presented e...
Farrar RG, Klei TR.Strongylus edentatus was successfully cultured in vitro to the fourth larval stage (L4). Some growth continued for periods of 40-50 days at which time reductions in viability were observed in some of the culture systems tested. Various combinations of media, sera, buffers and organ explant cultures were tested. All cultures were incubated at 37 C in an atmosphere of 95% air and 5% CO2. Larvae underwent growth and differentiation to the L4 in all medium-serum combinations with and without organ explant cultures. Development and growth did occur but viability was reduced to insignificant levels ...