Bites and Dog Viruses Flashcards by Grace Smith

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)

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What are the three dog breeds most associated with animal bites

Staffordshire terrier (aka American Pit bull)
Bullmastiff (Presa Canario)
Rottweile

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Major outcomes of animal bites

infection
trauma
disfigurement with required surgical repair
PTSD (selective mutism

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How much does the average dog bite cost insurers

The average dog bite claim cost insurers $16,600 (USD)

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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

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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

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Types of zoonoses

Zooanthroponosis (reverse zoonosis): transmission –man to animal

Anthropozoonosis: transmission animal to man

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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%)

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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

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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

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True or False

Rabies, the tenth most fatal infectious disease on the planet

True

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Rabies

Rabies rhabdoviridae
- Retrovirus
- Bullet shaped
- Can manifest as dumb or furious form
- ~100% death rate once sympotms show

Travels through the nervous system

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What animals tend to manifest dumb or furious form rabies

Furious form: Cats, dogs, and horses

Dumb form: ruminants (Cows, sheep)

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Incubation time of Rabies

1-12 months

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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)

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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?

1. Intestinal Form 2. Cardiac 3. 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)

1. **Vaccination**: best form of prevention 2. Keep animals away from contaminated areas and disinfect premises 3. 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)