Tylosin-responsive chronic diarrhea in dogs.

Fourteen dogs had shown chronic or intermittent diarrhea for more than 1 year. Diarrhea had been successfully treated with tylosin for at least 6 months but recurred when treatment was withdrawn on at least 2 occasions. Tylosin-responsive diarrhea (TRD) affects typically middle-aged, large-breed dogs and clinical signs indicate that TRD affects both the small and large intestine. Treatment with tylosin eliminated diarrhea in all dogs within 3 days and in most dogs within 24 hours. Tylosin administration controlled diarrhea in all dogs, but after it was discontinued, diarrhea reappeared in 12 (85.7%) of 14 dogs within 30 days. Prednisone given for 3 days did not completely resolve diarrhea. Probiotic Lactobacillus rhamnosus GG did not prevent the relapse of diarrhea in any of 9 dogs so treated. The etiology of TRD, a likely form of antibiotic-responsive diarrhea (ARD) is unclear. The following reasons for chronic diarrhea were excluded or found to be unlikely: parasites, exocrine pancreatic insufficiency, inflammatory bowel disease, small intestinal bacterial overgrowth, enteropathogenic bacteria (Salmonella spp., Campylobacter spp., Yersinia spp., or Lawsoni intracellularis), and Clostridium perfringens enterotoxin and Clostridium difficile A toxin. A possible etiologic factor is a specific enteropathogenic organism that is a common resident in the canine gastrointestinal tract and is sensitive to tylosin but difficult to eradicate. Additional studies are required to identify the specific cause of TRD.

Hereditary sterilizing short-tail sperm defect in Finnish Yorkshire boars.

A new infertility syndrome has recently been described in Finnish Yorkshire boars. Typical for the syndrome is total akinesia and severe tail malformation of the spermatozoa. Morphometric analysis was performed on semen smears from 20 affected and 18 control boars and on testicular tissue sections from 5 affected and 4 control boars. Semen morphometry revealed that, in affected boars, the length of the sperm tails was only 33% of that of the controls (15.4 microm vs. 47.0 microm, P < 0.0001). Typical for the spermatozoa of affected boars was also an abundant frequency of proximal cytoplasmic droplets (72.4% vs. 6.9%, P < 0.0001), whereas no major sperm-head abnormalities were recorded. In the testicular tissue samples, viewed at light microscopic level, the volume densities of seminiferous tubules or interstitium did not differ. The most characteristic change in the seminiferous epithelium of the affected boars was a reduced number of elongated spermatids. Densities of Sertoli cells and Leydig cells between affected and control boars did not differ. The ultrastructure of testicular tissue from affected boars showed severe alterations in the assembly of the midpiece and tail of the spermatozoa. As well, a typical finding in the seminiferous epithelium of affected boars was conspicuous deposition of lipid droplets. The pathogenesis of this syndrome severely affects spermiogenesis and motility. Spermatozoa have malformed, short tails, which never become motile. This syndrome is not manifested in the structure or function of other ciliated cells in the affected animals.