Dog Infectious Diseases Lecture Notes PDF

Lorraine Corriveau, DVM, DABVP(Canine and Feline Practice), DABLS Identify canine infectious diseases that can be prevented through vaccination Explain risk factors associated with acquiring infectious diseases Explain screening tests available to diagnose infectious diseases in dogs List the AHAA c...

Lorraine Corriveau, DVM, DABVP(Canine and Feline Practice), DABLS Identify canine infectious diseases that can be prevented through vaccination Explain risk factors associated with acquiring infectious diseases Explain screening tests available to diagnose infectious diseases in dogs List the AHAA canine vaccination protocols Describe the clinical signs of the infectious diseases Explain pathogenesis of the infectious diseases Vaccination protocols should be individualized based on risk factors, lifestyle, and life stage Credit: 2017 AAHA Canine Vaccine Guidelines-updated 2/2018 Canine Distemper +Parvovirus +Adenovirus-2 +/- Parainfluenza *Leptospirosis *B. bronchoseptica Rabies Canine Influenza H3N8+ H3N2 Lyme – Vaccination Modified Live (MLV) – Attenuated strain of virus Recombinant – Use viral DNA that expresses the protein that immunizes Administered subcutaneously (SQ) Includes: Adenovirus (hepatitis), Parvovirus, +/- Parainfluenza Vaccination series – >16 weeks old 2 vaccinations, 2-4 weeks interval 1 year booster, then every 3 years – < 16 weeks old Start as early as 6 weeks and finish > 16 weeks – High risk environments may benefit from final dose btw 18-20 wks 2-4 weeks interval Transmission – Viral shedding in feces – Aerosol droplets Clinical Signs – Coughing, fever, nasal discharge, seizures, neurologic signs such as involuntary muscle twitching and chewing movements of the jaw, vomit/diarrhea, hyperkeratosis of foot pads and nasal epithelium, enamel hypoplasia Risk Factors – Young animals in shelters, breeding kennels, dog parks, doggie day care Diagnosis Should be considered a ddx in any febrile condition in dogs w/ multisystemic manifestations Testing – Real time PCR – Immunofluorescent assay Conjunctival, tracheal, vaginal swaps, footpad biopsy Buffy coat of blood Urine sediment Bone marrow – Antibody titers or ELISA CSF compared to peripheral blood – Histologic lesions Pathogenesis - Paramyxovirus – Initially replicates in lymphatic tissue of respiratory tract – Infects all lymphatic tissue – Moves to epithelium of GI, respiratory, and urogenital systems – Invades optic and CNS nerves – Virus passes through bodily fluids Treatment – Symptomatic and supportive Broad spectrum antibiotics Balanced fluids Parenteral nutrition Antipyretics, analgesics, anticonvulsants Good nursing care – Unfortunately acute neuro presentation often progressive and so recovery unsuccessful Vaccination – MLV or recombinant 3 strains 2a, 2b, and 2c – Administered SQ – Puppy series: Begin at 6-8 weeks Every 2-4 weeks until >16wk – High virus pressure environments Maternal antibodies – last longer when prevalence higher – Genetic non-responders – purebred dogs Must do antibody test to ensure dog is immunized Testing – Viral PCR, electron microscopy, virus isolation – Fecal antigen IDEXX SNAP – does not cross react with MLV Tests for surface protein antigen of CPV Schultz RD, Larson LJ, Lorentzen LP. Effects of modified live canine parvovirus vaccine on the SNAP ELISA antigen assay. Paper presented at: International Veterinary Emergency Critical Symposium; September 18–21, 2008; Phoenix, AZ. Transmission – Direct and indirect contact Food and water bowls Leashes and collars Toys Hands and clothing of people who touch CPV infected dogs Pathogenesis – Virus destroys hematopoietic progenitor cells – Leukopenia and neutropenia – Infection in puppies chronic hepatitis – Vascular damage/thrombocytopenia Hemorrhages Coagulopathies Clinical signs – Fever, lethargy, weight loss, anorexia – Acute kidney failure – Jaundice – Abdominal discomfort – Vomiting/diarrhea Testing - antibody vs organism in tissues – Serology ELISA: Canine Leptospira spp. antibody –Qualitative positive or negative test –Detects antibodies to LipL32, a membrane protein found on pathogenic leptospires. –False positive in recently vaccinated dogs Testing – Serology MAT: Microscopic agglutination –False positive with vaccination –Slower test than PCR. –Follow up test may need to be performed –Inconclusive if given antibiotics before test Testing – PCR Test blood and urine simultaneously for bacterial DNA Need to perform test before antibiotics – False negative test Most useful during early stage of disease 7-14 days post infection – urine tests positive – Blood test may or may not be positive Dogs with chronic disease, tests could be negative False positive – rare – Culture of blood, urine, or tissue specimens is the only method to definitively identify the infecting serovar Blood may be cultured early in the clinical course urine is more likely to be positive 7–10 days after clinical signs appear Culture is rarely positive after antibiotic therapy has begun. Zoonotic Transmission – Enter body via mucus membranes: eyes, nose, mouth, skin – Multiply in the host’s bloodstream – Move to kidneys and other tissue to keep multiplying – Pass from kidneys to the urine and environment (water, soil) Vaccination – Adenovirus type 2 (protects for type 1) – Included in the DHPP vaccine – MLV or recombinant – Begin series at >= 6 weeks until 16 weeks old – Adults = Series of 2 vaccinations, 2-4 weeks apart – 1 year vaccination, then every 3 years Other Hosts – Foxes, wolves, coyotes, bears, lynx – Can be asymptomatic – Prevent outbreaks by vaccination Pathogenesis/Transmission – Ingestion of urine, feces, saliva – Travels to Peyer’s patches and tonsillar crypts Enters the bloodstream Disseminates to liver, kidney, spleen and lungs – Shed virus in urine for 6 months after recovery Clinical signs – Incubation period: 4-9 days – – – – – – – – Fever, anorexia, thirst Paresis, ataxia, blindness Enlarged tonsils Conjunctivitis Ocular and nasal discharge Seizures from forebrain damage Death 25% of recovered dogs develop bilateral corneal opacity Diagnosis – Difficult to differentiate from Distemper – Young dogs – Acute onset of bleeding – Acute onset of illness – Marked leukopenia – “Blue Eye” corneal cloudiness (Adenovirus-1) Immune complex reaction – Testing: ELISA, serology, PCR, virus isolation, Immunoflorescence, intranuclear inclusion bodies in liver Treatment – Symptomatic and supportive Limit secondary bacterial inf Support fluid and electrolyte balances Control hemorrhagic tendencies Vaccine – Included in the distemper vaccine and intranasal Bordetella – One of the pathogens of Infectious Tracheobronchitis or CIRD (canine infectious respiratory disease) complex – Boosters every 2-4 weeks until over 15 weeks old – Indicated in dogs that go to grooming, boarding, dog parks – Bordetella bronchoseptica: intranasal vs. injection vs. intraoral Transmission – Excreted from the respiratory tract for 2 weeks after infection Incubation period 3-10 days – Transmitted through the air and fomites – Highly contagious Clinical signs – Cough (dry or moist) – Nasal discharge – Low grade fever – Lethargy – Anorexia Diagnosis – Based on clinical signs of a cough suddenly developing 5-10 days after exposure to affected dogs – Thoracic radiography may be warranted to determine severity Treatment – Symptomatic for viral parainfluenza – Antibiotics of choice for Bordetella (used sparingly) SMZ/TMP Doxycycline/tetracycline Quinolones – Cough suppressant Vaccination – Killed – 3 months of age and older – State law dictated – Only veterinarians can administer the vaccine or if under direct supervision – In Indiana, first vaccine is for 1 year, then every 3 years Transmission – Saliva via bite wound – Saliva entering skin through a cut, eyes, mouth, nose – High risk pet include dogs that live outside or interact with wildlife Clinical signs – Anxiety – Confusion – Partial paralysis – Excitation – Agitation – Aggression – Hypersalivation – Difficulty swallowing Vaccination – 2 injections 2-4 weeks apart, then annually – Three types Killed whole cell bacterin OspA and OspA+C- adjuvanted Recombinant Osp A – Non-adjuvanted Chimeric Osp C + recombinant Osp A – adjuvanted Dogs at risk – Lyme disease is present nationwide Northeast, upper Midwest, Pacific coast – Active dogs that hike in the woods – Dogs that play in fields – Dogs that spend time in the yard Transmission – Ixodes spp. (deer tick) Nymphs (spring) Adults (spring & fall) – Ticks carry Borrelia burgdorferi – Tick takes a blood meal -> attach for 24-48 hours -> bacteria moves to salivary glands -> injects B. burgdorferi -> joints, organs, neural tissue Clinical signs – Fever – Lethargy – Shifting leg lameness – Arthritis/swollen joints – Anorexia – Lymphadenomegaly Diagnosis – Based on many factors – Persistence of antibodies Lyme Quant C6 – C6 peptide on the VisE surface protein of Borellia – Long incubation periods – Protein-losing nephropathy Lyme nephritis – Hypoalbuminemia – Edema – Renal failure Treatment – 4 weeks of antibiotic doxycycline 10mg/kg PO q 12 hr* Beta-lactams – amoxi/clavamox - 20mg/kg PO q 8 hr Prevention – – – – Tick avoidance Prompt removal of tick Tick preventives +/- vaccination Vaccination – Killed vaccine – Adjuvanted – 2 injections 2-4 weeks apart, annually Transmission – Direct contact – Indirect contact – Contaminated surfaces – H3N8 sheds 24 hours – 10 days post infection – H3N2 sheds can intermittently shed up to 24 days Clinical signs – Sneezing – mild form – Coughing – 5-8% can lead to pneumonia – Nasal discharge – Fever – Anorexia – 10-20% subclinical infection, but still infective Diagnosis – Nasal/pharyngeal swabs for PCR testing if ill for