Infectious Diseases
Brucella canis
Cause: Bacteria of the Brucella sp. are well known for causing infertility in dogs. B. canis is the most common of the brucellosis-causing bacterial strains found in dogs and, as such, is routinely screened for by serological testing as part of the breeding management plan.
Symptoms: Males infected with Brucella canis are sterile and asymptomatic for disease. Epididymitis (refer to testicular infections) with epididymal swelling occurs 3 to 5 weeks after the dog becomes infected but may only be evident upon palpation of the scrotum. Morphologic abnormalities of the sperm become detectable by 5 weeks after infection. Eventually, atrophy of the testicles becomes apparent in chronically affected dogs.
Diagnosis: Diagnosis of B. canis is by serological testing and concurrent blood cultures. Limitations to serological testing for B. canis, however, do exist and typically occur with use of the rapid slide agglutination test (RSAT) or the tube agglutination test which may result in false-positives or false-negatives. False-positives should be suspected if a dog is asymptomatic or concurrent blood cultures drawn at the same time as serological samples are negative for bacterial growth. Follow-up assessment with the agar-gel immunodiffusion (AGID) test will rule-out the possibility of false-positive results. False-negatives will occur if serological testing is conducted within a 4 week period after the dog has initially contracted B.canis. Therefore, all negative tests should be confirmed by repeat testing 30 days from the first test before considering a dog to be free of infection. Dogs may also become infected with other strains of Brucella sp. that typically infect livestock. Dogs with symptoms consistent with brucellosis but that have negative serological testing for B. canis and have a history of exposure to livestock may harbor one of the other strains such as B. abortus, B. suis, and B. melitensis. Since serological tests for B. canis will not cross-react with these other Brucella sp., dogs suspected of carrying an alternate strain of Brucella should be tested specifically for these other strains.
Treatment and Prognosis: Though B. canis is most often conceived as being transmitted from dog to dog during the actual act of copulation, the primary mode of transmission actually occurs via oronasal contact with infected body fluids. Therefore, spread of infection is not limited to breeding contact and as such, once introduced into a breeding kennel, the highly infectious B. canis will quickly spread through the population. Long-term, multiple treatments with antibiotics may assist in controlling symptoms and extent of infection within an individual dog, however, antibiotic treatment has limited efficacy for cure and the dog will remain potentially infectious to other dogs. As such, infected dogs should be neutered and removed from the breeding kennel environment to prevent spread to other breeding dogs. Retesting should be performed 6 months following completion of the antibiotic regimen to assess treatment efficacy. The alternative for controlling spread of B. canis is euthanasia of all confirmed-infected dogs.
Mycoplasmas and Ureaplasmas
Cause: These organisms are of the Mycoplasmataceae family and normally inhabit the canine urogenital and nasopharyngeal tracts. If, however, there is an increase in the number of these organisms in comparison to the other common organisms also inhabiting the male urogenital tract, then there is often an increase in incidence of infertility, testicular infections and prostatitis.
Symptoms: Males infected with Mycoplasma or Ureaplasma demonstrate fertility problems with or without evidence of testicular infection, prostatitis, or scrotal swelling. Infection leads to inflammatory processes that create an abnormal environment for production of spermatozoa. Additional effects on sperm may include alteration of sperm motility, interference of normal sperm metabolism by which the sperm recognizes the ova, impairment of ova-penetrating ability, and inducing autoimmune damage to the sperm.
Diagnosis: Culture of semen samples for the purpose of identifying an increased proportion of Mycoplasma or Ureaplasma growth compared to growth of other microorganisms which normally inhabit the urogenital tract provides a method of diagnosis for infection.
Treatment and Prognosis: Antibiotic treatment for a minimum of 10 to 14 days is used for the purpose of eradicating infections with Mycoplasma and Ureaplasma. Some Mycoplasma strains are resistant to the standard Erythromycin treatment and may require therapy with Tylosin, which offers a broader spectrum for elimination of the various Mycoplasma strains. Semen cultures are typically repeated after completion of therapy to ensure complete elimination of the infectious organisms. Dogs infected with Mycoplasma or Ureaplasma should not be used for breeding until antibiotic treatment is completed and follow-up cultures confirm that the dog is no longer a carrier. Stud dogs should not be allowed to naturally breed bitches suspected of carrying Mycoplasma or Ureaplasma. When the bitches' status is unknown, breeding by artificial insemination is the safest procedure.
Brucella canis
Cause: Bacteria of the Brucella sp. are well known for causing infertility in dogs. B. canis is the most common of the brucellosis-causing bacterial strains found in dogs and, as such, is routinely screened for by serological testing as part of the breeding management plan.
Symptoms: Males infected with Brucella canis are sterile and asymptomatic for disease. Epididymitis (refer to testicular infections) with epididymal swelling occurs 3 to 5 weeks after the dog becomes infected but may only be evident upon palpation of the scrotum. Morphologic abnormalities of the sperm become detectable by 5 weeks after infection. Eventually, atrophy of the testicles becomes apparent in chronically affected dogs.
Diagnosis: Diagnosis of B. canis is by serological testing and concurrent blood cultures. Limitations to serological testing for B. canis, however, do exist and typically occur with use of the rapid slide agglutination test (RSAT) or the tube agglutination test which may result in false-positives or false-negatives. False-positives should be suspected if a dog is asymptomatic or concurrent blood cultures drawn at the same time as serological samples are negative for bacterial growth. Follow-up assessment with the agar-gel immunodiffusion (AGID) test will rule-out the possibility of false-positive results. False-negatives will occur if serological testing is conducted within a 4 week period after the dog has initially contracted B.canis. Therefore, all negative tests should be confirmed by repeat testing 30 days from the first test before considering a dog to be free of infection. Dogs may also become infected with other strains of Brucella sp. that typically infect livestock. Dogs with symptoms consistent with brucellosis but that have negative serological testing for B. canis and have a history of exposure to livestock may harbor one of the other strains such as B. abortus, B. suis, and B. melitensis. Since serological tests for B. canis will not cross-react with these other Brucella sp., dogs suspected of carrying an alternate strain of Brucella should be tested specifically for these other strains.
Treatment and Prognosis: Though B. canis is most often conceived as being transmitted from dog to dog during the actual act of copulation, the primary mode of transmission actually occurs via oronasal contact with infected body fluids. Therefore, spread of infection is not limited to breeding contact and as such, once introduced into a breeding kennel, the highly infectious B. canis will quickly spread through the population. Long-term, multiple treatments with antibiotics may assist in controlling symptoms and extent of infection within an individual dog, however, antibiotic treatment has limited efficacy for cure and the dog will remain potentially infectious to other dogs. As such, infected dogs should be neutered and removed from the breeding kennel environment to prevent spread to other breeding dogs. Retesting should be performed 6 months following completion of the antibiotic regimen to assess treatment efficacy. The alternative for controlling spread of B. canis is euthanasia of all confirmed-infected dogs.
Mycoplasmas and Ureaplasmas
Cause: These organisms are of the Mycoplasmataceae family and normally inhabit the canine urogenital and nasopharyngeal tracts. If, however, there is an increase in the number of these organisms in comparison to the other common organisms also inhabiting the male urogenital tract, then there is often an increase in incidence of infertility, testicular infections and prostatitis.
Symptoms: Males infected with Mycoplasma or Ureaplasma demonstrate fertility problems with or without evidence of testicular infection, prostatitis, or scrotal swelling. Infection leads to inflammatory processes that create an abnormal environment for production of spermatozoa. Additional effects on sperm may include alteration of sperm motility, interference of normal sperm metabolism by which the sperm recognizes the ova, impairment of ova-penetrating ability, and inducing autoimmune damage to the sperm.
Diagnosis: Culture of semen samples for the purpose of identifying an increased proportion of Mycoplasma or Ureaplasma growth compared to growth of other microorganisms which normally inhabit the urogenital tract provides a method of diagnosis for infection.
Treatment and Prognosis: Antibiotic treatment for a minimum of 10 to 14 days is used for the purpose of eradicating infections with Mycoplasma and Ureaplasma. Some Mycoplasma strains are resistant to the standard Erythromycin treatment and may require therapy with Tylosin, which offers a broader spectrum for elimination of the various Mycoplasma strains. Semen cultures are typically repeated after completion of therapy to ensure complete elimination of the infectious organisms. Dogs infected with Mycoplasma or Ureaplasma should not be used for breeding until antibiotic treatment is completed and follow-up cultures confirm that the dog is no longer a carrier. Stud dogs should not be allowed to naturally breed bitches suspected of carrying Mycoplasma or Ureaplasma. When the bitches' status is unknown, breeding by artificial insemination is the safest procedure.
