Bites and Dog Viruses Flashcards
What are the most commmon sources of animal bites?
- Dog: most common cause of reported bites (80-90% of bites)
- Cat: second most common cause of reported bites (5-15% of bites)
- People: third most common cause of reported bites (2.3-23% bites reported by ER physicians)
What are the three dog breeds most associated with animal bites
- Staffordshire terrier (aka American Pit bull)
- Bullmastiff (Presa Canario)
- Rottweile
Major outcomes of animal bites
- infection
- trauma
- disfigurement with required surgical repair
- PTSD (selective mutism
How much does the average dog bite cost insurers
The average dog bite claim cost insurers $16,600 (USD)
Regulations applying to restricted dogs
- Must hold a restricted dog licence
- Must carry liability insurence (no less than $1 million dollars)
- Dog must be muzzled, leashed, and under control
No penalities if the resticted dog is provoked
Public Health
“the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals
Types of zoonoses
Zooanthroponosis (reverse zoonosis): transmission –man to animal
Anthropozoonosis: transmission animal to man
Animal Bites: A Brew of INfectious Organisms
Most bites from dogs and cats are polymicrobial (2-4 different or microorganisms isolated/wound)
- usually including 1 anaerobic organism per wound (38% cat bites/ 76% dog bites)
- Anaerobic: Bacteroides (Capnocytophaga canimorsus), Fusobacterium Peptostreptococcus
- Aerobic: Staphylococcus, Streptococcus, Pasteurella multocida
- Pasteurella multocida: normal flora of oral cavities (cats 70-90%; dogs 50-66%)
Pasteurella multocida
Pasteurella multocida: normal flora of oral cavities (cats 70-90%; dogs 50-66%)
- Cat bite wounds: 50-80%
- Dog bite wounds: 25%
- Cats: 24 hours following bite: swelling, pain,
Sequelae: septic (arthritis),
osteomyelitis, sepsis, pneumonia,
endocarditis and meningitis,
Death can occur in systemic injury
following untreated infection
Capnocytophaga canimorsus
Pathogen of dog bites
Found in oral cavity: 18% cats and 16% dogs
- Serious injury in immunocompromised patients infected with Capnocytophaga canimorsus
- Local infection, sepsis, myocarditis, meningitis, eye infections and pneumonia
- Rapid progression of disease can lead to death
True or False
Rabies, the tenth most fatal infectious disease on the planet
True
Rabies
Rabies rhabdoviridae
- Retrovirus
- Bullet shaped
- Can manifest as dumb or furious form
- ~100% death rate once sympotms show
Travels through the nervous system
What animals tend to manifest dumb or furious form rabies
Furious form: Cats, dogs, and horses
Dumb form: ruminants (Cows, sheep)
Incubation time of Rabies
1-12 months
Treatment of Rabies
1) clean wound immediately with soap/iodine solution and water
2) Human rabies immunoglobulin (once at the beginning of treatment) followed by vaccination
Prevention: vaccination
- Vaccines are available for dogs, cats, horses (i.e. Rabvac-3) and people (IMOVAX)
Paramyxovirus
- “Sloppy genetics”
- Relatively easy to transfer species
Canine Distemper
Paramyxovirus: Single stranded RNA virus
- Highly contagious: the second most important infectious disease affecting canines
- Affects domestic and wild cinines
- Also ferrets and rarely cats
- Resivoir in wild candids and domestic dogs
Common Paramyxoviruses
Mammals
- Rinderpest
- phocine distemper
- morbillivirus
- wild feline
Terrrestrial Carnivores
- Ferret (canine distemper)
- Procyonidae
- Viverridae
Avian
- Newcastle’s disease
Humans
- Nipah virus
- Measles
Transmission of canine distemper
- Aerosol (water droplets, nasal), other secretions urine, feces, ocular secretion…tears)
- Shared food and water bowls
- Transplacental (mother to fetus)
Highly contagious: shed 60-90 days carrier animals.
Survive in environment: 48 hours @ 25C and 14 days @ 5C
Pathenogenesis of Canine distemper
Pathogenesis (nervous, respiratory and lymphoid tissue)
- 24 hours following exposure (i.e. lungs), virus travels to lymphoid tissue (lymph nodes, spleen, tonsils) to replicate to large numbers (day 4-6)
- Travels to intestine and nervous tissue (day 8-9)
Clinical Signs of Canine Distemper
Clinical signs: up 70% dogs (subclinical), show very mild to no clinical signs and these dogs recover
- Acute form: high mortality- occurs within 14-21 days of exposure
- Respiratory signs and intestinal signs (1-3 weeks), hemorrhage, pneumonia, conjunctivitis (surrounding eye)
- Nervous tissue (inflammation, demyelination): paralysis, seizures (‘chewing-gum fits’), visual and vestibular changes
- Immunosuppression
- Chronic: skin thickening (seen with neurological signs), eye, lung, brain, gut, vision problems
White Matter Injury
Canine Distemper
White matter: axons
- Loss of axons myelin
- vacuolation
- Myelin helps ‘insulate’ the axon
- Needed for normal nerve signal transduction
Demyelination is an effect of Canine Distemper
History and effected species
Canine Adenovirus-1 (CAV-1)
Infectious canine hepatitis (ICH)
ICH was previous known as enzootic encephalitis of foxes was first seen in dogs 1930
- Infects: dogs, wild canids (fox, wolf, coyotes), Ursidae (bears)
- Infections widespread (Europe, NA, Australia)
- Member of adenovirus (DNA virus)
- Infects/replicates liver, kidney and endothelial cells (cells that line blood vessels endothelial cells)
Transmission and Mortality
Canine Adenovirus-1 (CAV-1)
Infectious canine hepatitis (ICH)
- Transmission: animal-animal contact-saliva, urine, feces, respiratory droplets, or indirect (environment)
- Animals shows signs of illness: 4-9 following exposure
- Mortality 10-30% in naïve animals
Clinical Signs
Canine Adenovirus-1 (CAV-1)
Infectious canine hepatitis (ICH)
- High fever (>40C; dog normal 37.5-39.5)
- Depressed, inappetent, vomiting and diarrhea
- Abdominal pain (enlarged sore liver), hemorrhagic diathesis (‘tendency to bleed’), epistaxis (nose bleed), congested or pale mucous membranes (dark red or white gums)
- Neurological signs: seizures
- Blue eye: surviving acute episode (immune complex disease)
Blue Eye Syndrome
Immune complex disease
- bilateral corneal opacity
- Anterior uveitis
They literally have blue eyes
- Some animals that survive Canine Adenovirus get this
- Scarred over corneas
- The whole uvia is getting inflamed
Occurs when antibodies that the animal makes from the antigen binds, but transfers to other tissues (type 3 Sensitivity)
- This is usuallly the kidney
- In this case, it causes Blue Eye
- Can occur after infection
Infectious tracheobronchitis
(kennel cough)
- Highly infectious disease; often self limiting, Pathogens usually infect respiratory epithelium
- Cause mainly by Canine Adenovirus-2 and Parainfluenza virus (paramyxovirus) and often associated with Bordetella bronchiseptica and Mycoplasma species
- Dry cough, but in complicated events (puppies, immunocompromised dogs) will lead to bronchopneumonia
Why use CAV-2 in vaccine (protect against CAV-1) when CAV-1 is much more pathogenic the dog (and should be better protection)
It negates the risk of developing blue-eye (using canine adenovirus-1 has the chance of causing it)
Parvovirus
Parvovirus: small virus non-enveloped single stranded DNA virus (Latin parvus:small)
- Affects domestic and wild canids (wolves and foxes)
- Relatively new disease: identified late 1970’s and spread worldwide by 1978
Almost identical to feline panluekopenia virus
Needs actively mitotic cells (dividing cells) to replicate
Shedding and Enviromental Resistance
Parvovirus
- Shed by infected or carrier dogs and shedding can last 2 weeks.
- Can last in the environment 5-9 months and thus is very difficult to eradicate
- Keep unprotected animals away from areas that may have parvovirus exposure
What are the three forms of Parvovirus?
- Intestinal Form
- Cardiac
- Neurlogical
Intestinal Form Parvovirus
Stage 1:
- Virus uptake orally: dissemiates to all lymphoid tissues and destroys them
- Dog becomes immunocompromised
Stage 2:
- Infects and destroys intestical epithelium (especially progenitors cells in the crypts)
Up to 91% fatality if unvaccinated animal is not treated
Parvovirus: Heart
Parvovirus will infect heart muscle of growing puppies
- Can cause massive cell death and lead to heart failure, often within the first 2 months of life
Parvovirus: injured intestine
Pin-point (petechial) hemorrhages
- “drill though intestinal tract”
Slough mucosa:(mucosal casts)
Parvovirus: Heart- myocardial necrosis
Will cause necrosis of heart cells (cardiomyocytes)
- This will kill the animal
Mostly infects very young puppies
Parvovirus: Brain (relatively uncommon)
Inflammation and necrosis of the brain
Similar effect to Feline parvovirus
- Only effects very young puppies
- Like a few days old
Management for all viruses
Dogs (parvovirus)
- Vaccination: best form of prevention
- Keep animals away from contaminated areas and disinfect premises
- Commercial virucidal products or 5% bleach diluted (1:20 parts)
- Intensive hospitalization and veterinary care with intestinal form
- Cardiac form and neurological form: treatment is often unrewarding (if severe)
