Cultivation and Maintenance of Sphaerophorus necrophorus Part I: An Anaerobic Medium for Aerobic Incubation

Out of 185 media formulated and studied for the growth of Sphaerophorus necrophorus, ten were selected for intensive investigation. Their ability to promote growth was compared photometrically. Medium 156 made up of Brewer's thioglycollate broth, yeast extract, L-cystine, and ascorbic acid, was found to yield a very heavy growth. The viability of S. necrophorus was maintained indefinitely by weekly subcultures. When not subcultured, all isolates remained viable for fifteen weeks and some isolates for 30 weeks at 37°C.

Twenty-nine isolates were tested. No variation in maximum growth was noticed.

Medium 156 is an optimum medium for S. necrophorus. It can be incubated aerobically without interfering with maximum growth. The medium does not deteriorate when stored for at least 12 weeks at room temperature.

     

Day-blindness in three dogs: clinical and electroretinographic findings

A 6-month-old Rhodesian ridgeback-cross, a 6-year-old Chihuahua and a 12-month-old Australian cattle dog were presented to the authors with a history of colliding with obstacles in daylight. Ophthalmic examination was normal and all three dogs successfully negotiated obstacle courses in dim light. In daylight the dogs became suddenly blind and repeatedly collided with obstacles. Elecroretinography (ERG) revealed no retinal activity to high frequency (30 Hz), bright intensity blue light retinal stimulation by any dog, confirming cone dysfunction. Achromatopsia has previously been recorded in Alaskan malamutes and miniature poodles. This clinical case series illustrates the characteristic behavioral presentation and the electroretinographic findings of severe day-blindness and demonstrates that this condition may exist in other breeds of dogs.     

Isolates of Verticillium dahliae Pathogenic to Crucifers Are of at Least Three Distinct Molecular Types

ABSTRACT Diverse isolates of the soilborne wilt fungi Verticillium dahliae and V. albo-atrum were studied to understand the nature and origins of those infecting cruciferous hosts. All isolates from cruciferous crops produced microsclerotia, and the majority produced long conidia with a high nuclear DNA content; these isolates were divided into two groups by amplified fragment length polymorphism (AFLP) analysis. One group could be subdivided by other criteria such as rRNA sequences and mitochondrial DNA restriction fragment length polymorphism (RFLP) analysis. Two crucifer isolates were short spored and had a low nuclear DNA content. The results are consistent with the crucifer isolates being interspecific hybrids. The long-spored isolates are best regarded as amphihaploids (or allodiploids) with the AFLP groups probably each representing separate interspecific hybridization events. The short-spored crucifer isolates appear to be derived from interspecific hybrids and are here called 'secondary haploids'. Molecular evidence suggests that one parent in the crosses was similar to V. dahliae. The other parent of the amphihaploids seems to have been more similar to V. albo-atrum than to V. dahliae, but was distinct from all isolates of either species so far studied. The implications for the taxonomy of crucifer isolates are discussed and the use of the name V. longisporum, proposed elsewhere for just some of these isolates, is discouraged.     

Effects of monoamines formed in the cecum of horses on equine digital blood vessels and platelets

OBJECTIVE: To determine in vitro vasoactive potency of monoamines formed in the cecum and found in the systemic circulation of horses. SAMPLE POPULATION: Segments of digital blood vessels obtained from 6 healthy mixed-breed horses and ponies euthanatized at an abattoir and platelets isolated from 4 healthy ponies. PROCEDURE: Paired rings of digital artery and vein from the same horse were examined, and isometric tension was recorded. Concentration-response curves for tryptamine (TRP), tyramine (TYR), phenylethylamine (PEA), isoamylamine (IAA), and isobutylamine (IBA) were obtained. Vasoconstrictor mechanisms were investigated for TRP and TYR by the use of antagonists. Washed platelets loaded with [3H]-5-hydroxytryptamine (5-HT) were incubated with monoamines; the amount of radioactivity displaced after 30 minutes was estimated. RESULTS: TRP, TYR, and PEA were potent constrictors of arteries and veins, with TRP and TYR being more potent in veins than arteries. Constrictions induced by TYR were inhibited by benextramine (alpha-antagonist) and nisoxetine (neuronal-uptake blocker), whereas TRP responses were inhibited by ketanserin (5-HT receptor antagonist). All 5 amines displaced 5-HT from platelets with the order of potency being TYR > TRP > PEA > IAA > IBA. CONCLUSIONS AND CLINICAL RELEVANCE: Amines from the equine cecum cause digital vasoconstriction. The most potent (TRP and TYR) cause selective venoconstriction. Tyrosine activates predominantly alpha-adrenoceptors through the release of neuronal norepinephrine, whereas TRP activates 5-HT receptors. All amines tested released 5-HT from platelets. Amines formed in the cecum and released into the systemic circulation warrant additional investigation as trigger factors for digital ischemia and subsequent laminitis.     

Tenosynovitis of the digital flexor tendon sheath and annular ligament constriction syndrome caused by longitudinal tears in the deep digital flexor tendon: a clinical and surgical report of 17 cases in warmblood horses

REASONS FOR PERFORMING STUDY: Inflammation of the digital flexor tendon sheaths is a chronic and nebulous condition often unresponsive to medical and surgical treatment. OBJECTIVES: To evaluate the incidence of longitudinal tears (LT) as the underlying cause of chronic tenosynovitis and annular ligament constriction syndrome (ALCS) in warmblood horses. METHODS: The records of 25 horses with chronic tenosynovitis and ALCS in which tenoscopical inspection of the digital flexor tendon sheath (DFTS) was performed between 1999-2000 were reviewed. Of 25 horses, 17 were diagnosed with an LT in the deep digital flexor tendon (DDFT). All horses had a history of distension of the DFTS and/or signs of an ALCS. All cases presented typical signs of a chronic inflamed DFTS on ultrasonography and 11 horses showed ultrasonographic changes (echogenic material or an irregular outlining) at the lateral or medial border of the DDFT. The diagnosis of LTs of the DDFT was established in all cases by tenoscopy. Surgical treatment consisted of removal of the torn collagen fibrils using a mechanical resector and decompressing the fetlock canal by a transection of the palmar annular ligament (PAL) using a hook knife under tenoscopic control. RESULTS: Ten horses became sound and resumed their previous level of work, 3 horses remained lame, 4 horses returned to previous level of work but needed intrasynovial treatment of the DFTS and reduced competition frequency to remain sound. CONCLUSIONS: Horses presented with chronic inflamed DFTS and/or ALCS might suffer from LTs in the DDFT; however, the diagnosis cannot be established with absolute certainty using only ultrasonography. Longitudinal tears should be suspected if ultrasonographic changes are present lateral or medial to the border of the DDFT but tenoscopical examination of the tendon sheath is essential to establish an accurate diagnosis and an effective treatment. POTENTIAL RELEVANCE: The presence of these LTs might explain why some cases of chronic tenosynovitis of the digital flexor tendon sheath and/or ALCS do not respond on surgical transection of the PAL alone without tenoscopy.     

Hematogenous septic arthritis in the dog: results of five patients treated nonsurgically with antibiotics

This retrospective study evaluates the effectiveness of nonsurgical treatment using antibiotics to treat hematogenous septic arthritis in five dogs. Giant-breed dogs were over-represented, with all dogs <1 year of age. Synovial fluid cultures were positive in all cases, with common bacterial species isolated that included Streptococcus B-haemolytic spp., Pasteurella multocida, and Staphylococcus intermedius. Dogs treated with appropriate duration and selection of antibiotics had clinical resolution with no residual deficits. This report and a previous clinical report demonstrate that hematogenous septic arthritis can be successfully treated nonsurgically with antibiotic therapy.     

Effect of short-chain fatty acids on contraction of smooth muscle in the canine colon

OBJECTIVE: To determine effects of short-chain fatty acids (SCFA) on canine colonic smooth muscle. SAMPLE POPULATION: Colonic tissue obtained from 14 healthy dogs. PROCEDURE: Short-chain fatty acid (SCFA; acetate, propionate, and butyrate; 1 to 100 mmol/L)-induced contractions were compared with responses obtained with acetylmethylcholine (AMCh; 10(-4) mol/L). Roles of enteric neurons, cholinergic receptors, calcium stores in the sarcoplasmic reticulum, and extracellular calcium in the SCFA-induced responses were investigated by incubating muscle strips with tetrodotoxin (1 micromol/L), atropine (1 micromol/L), ryanodine (10 micromol/L), nifedipine (1 micromol/L), ethylene glycol-bis (beta-aminoethylether)-N,N,N',N'-tetra-acetate (EGTA; 0.1 mmol/L), or an extracellular calcium-depleted (zero extracellular calcium) solution prior to the addition of propionate or butyrate. RESULTS: Incubation with SCFA elicited isometric stress responses (0.25 to 2.15 x 10(4) N/m2) in colonic longitudinal smooth muscle. Maximal responses to butyrate and propionate (50 mmol/L) were 37 and 23%, respectively, of the maximal AMCh response. Acetate was least effective in stimulating contractile responses. Tetrodotoxin and atropine did not affect SCFA-induced contractions. Nifedipine and zero extracellular calcium solution abolished responses to butyrate and propionate, whereas EGTA attenuated (> 60%) but did not abolish those responses. Ryanodine did not affect SCFA-induced contractile responses. The SCFA did not affect colonic circular smooth muscle. CONCLUSIONS AND CLINICAL RESPONSE: The SCFA stimulate longitudinal but not circular colonic smooth muscle contractions via a direct effect on smooth muscle. The mechanism of the SCFA effect appears to involve the influx of extracellular calcium. These findings may account for some of the effects of fiber on canine colonic motility [corrected].     

Effect of immunosuppressive doses of cyclosporine on pancreatic beta cell function in pigs

OBJECTIVE: To evaluate whether immunosuppressive doses of cyclosporine (CsA) have an adverse effect on the liver, kidney, and pancreatic beta cells of pigs. ANIMALS: 8 juvenile 8-week-old Landrace X Large White crossbred pigs. PROCEDURE: CsA (100 to 140 mg/kg) was administered orally to euglycemic pigs to reach whole blood trough concentrations of approximately 1500 ng/mL. To determine pancreatic beta cell function, plasma C-peptide and insulin concentrations were measured in response to i.v. administration of glucose, glucagon, arginine, and oral administration of glucose. Effects on liver and kidney were determined by monitoring serum measurements of liver function and serum creatinine concentrations, respectively. RESULTS: Plasma concentrations of C-peptide were significantly lower in euglycemic CsA-treated pigs, compared with control pigs, following i.v. administration of glucose, glucagon, arginine, and oral administration of glucose. Furthermore, the glucose clearance rate was decreased in euglycemic CsA-treated pigs, compared with control pigs. Serum creatinine concentrations and 4 of 7 serum measurements of liver function were not adversely affected by CsA administration. Serum concentrations of bilirubin and albumin were significantly increased, and serum alanine aminotransferase activity was significantly decreased in CsA-treated pigs, compared with control pigs. Histologic evaluation of liver and kidney sections revealed no pathologic findings in CsA-treated or control pigs. CONCLUSIONS AND CLINICAL RELEVANCE: In our study, immunosuppressive doses of CsA caused an impairment of porcine pancreatic beta cell function, but did not have toxic effects on the kidney. However, on the basis of changes in serum bilirubin and albumin concentrations and alanine aminotransferase activity, subclinical toxic effects on the liver did occur when immunosuppressive doses of CsA were administered.     

Rickettsial infection in farmed Atlantic salmon in eastern Canada

The cause of death in a postsmolt, Atlantic salmon population with elevated levels of mortalities was investigated. Diagnosis of a rickettsia-like organism was based on gross pathology, histopathology, differential staining, electron microscopy and fluorescent antibody tests. The course of the infection and response to treatment are discussed. This is the first reported occurrence of salmon rickettsias in the Atlantic coast of North or South America.