Research Paper for the Pet Technician Certificate :
Module 3 -Infectious Disease
Owner: Alice Lam
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Symptoms include fever, eyes discharge, running nose, vomit and diarrhea, dehydration, excessive salivation, coughing and/or labored breathing, loss of appetite, weight loss, hardening of the footpads and nose, seizures of any part of the body, in particular, the developing of “chewing gum fits”.
Another lasting symptom commonly is enamel hypoplasia. Puppies, especially, might suffer damage to the enamel of teeth that are not completely formed or those that have not yet grown through the gums, as a result of the virus killing the cells responsible for the production of tooth enamel. Teeth affected tend to erode quickly.
The animal may also show signs of sensitivity to light, coordination disorder, prolonged circling, increased sensitivity to sensory stimuli such as pain or touch, and deterioration of motor capabilities. Sometimes, it may cause blindness and paralysis.
HOW THE CARRIER STATE DEVELOPS
The virus first enters the bronchial lymph nodes and tonsils 2 days after exposure, then the blood stream on the 2nd or 3rd day. A first round of acute fever tends to begin around the 3rd to 8th day, which is often accompanied by a low white blood cell count, especially of lymphocytes, as well as low platelet count. These signs may go unnoticed or be accompanied by loss of appetite, may or may not be accompanied by anorexia, running nose, and discharge from the eye. This first round of fever typically recedes rapidly within 96 hours, and then a 2nd round of fever begins around the 11th or 12th day and lasts around a week.
Gastro-intestinal and respiratory signs may follow and are usually complicated by bacterial infections. Overgrowth of the skin of the footpads (“hardpad” disease) and hardening of the nose may be seen.
This is called the Mucosal Phase.
Neurological signs will then gradually appear. These may include seizures in the form of : 1) localized involuntary twitching and seizures of a muscle or group of muscles, such as in the leg or face, 2) slight or complete paralysis, often most noticeable in the hind limbs as failure of muscle coordination, followed by weakness and paralysis in all 4 legs, and 3) the development of chewing-gum fits.
The seizures become more frequent and severe as the disease progresses. The dog may fall on its side and paddle its legs. Involuntary urination and defecation sometimes occur.
This is the Neurologic Phase.
Younger puppies or dogs with weak immunity often die during the mucosal phase while stronger ones may have relatively mild mucosal signs and may not be apparent until reaches the neurologic phase.
WHAT ARE THE CIRCUMSTANCES THAT MAKE THE CARRIER ANIMAL INFECTIOUS TO OTHER ANIMALS
CDV spreads in 6 to 22 days after exposure, through aerosol droplets and contact with infected bodily fluids. The time between infection and disease is 3-8 days for first fever to appear and 14 to 18 days for full infection is noted.
It is with this long incubation period that stray animals lacking vaccinations are more susceptible to the virus and be the host to spread to the community. The typical distemper suspect is a rescue dog or a pet shop puppy, usually with questionable vaccination history or an as yet incomplete vaccination series, or dogs or puppies which has been housed with other rescue dogs. Puppies from three to six months old are particularly susceptible. Puppies and dogs that have not received their shots can then be easily infected.
Moreover, an infection of CDV may or may not be noticeable as the symptoms may be mild with few or even no signs, or the attack comes strong at a late stage when the patient is already suffering from acute health conditions and showing neurological signs, which may not come until several weeks or months later. Infected dogs with no signs at all may be spreading the infectious virus for months without being discovered.
HOW THE DISEASE IS SPREAD
The Canine Distemper Virus (CDV) transmission must involve dog to dog contact or at least contact with extremely fresh infected body secretions. The infected dog typically infects other dogs via coughing infected respiratory secretions though the virus is shed in most other body secretions including nasal and ocular secretions, faeces and urine. It can also be spread by food and water contaminated with these fluids. The virus enters the new host via the nose or mouth and promptly begins to replicate.
WHAT MEASURES CAN BE TAKEN TO MINIMISE THE SPREAD TO OTHER ANIMALS IN THE SAME HOUSEHOLD?
Infected animals should be quarantined from other dogs for several months due to the length of time the animal may shed the virus.
The virus is destroyed in the environment by routine cleaning with disinfectants, detergents, or drying.
It does not survive in the environment for more than a few hours at room temperature (20–25°C), but can survive for a few weeks in shady environments at temperatures slightly above freezing.
It, along with other labile viruses, can also persist longer in serum and tissue debris.
Vaccination is the best available prevention for canine distemper. Puppies should be vaccinated when they are 6 weeks old and then at 2- to 4-week intervals until they are 14 to 16 weeks old. Annual revaccination has been suggested because of the breaks in neurologic distemper that can occur in stressed or diseased dogs or those with weakened immune systems.
