Not so ‘Fantastic Four’ viral diseases in canines

Dr Diksha Kandpal
Know more about the four most common viral diseases in dogs – rabies, canine parvovirus, canine distemper, and infectious canine hepatitis. Find out signs and symptoms and best treatment options to keep your furry friends safe and healthy.

Viral diseases are caused by viruses which are widespread in occurrences and vary with the intensity of their virulence. Viruses are the microorganism which requires a host organism to survive and are unable to do so in their absence. Viruses have a wide range of host including humans and animals. The increased incidences of viral disease have become a concern for humans as well as animals. Viral diseases most commonly encountered in dogs include – canine distemper (CD), infectious canine hepatitis (ICH), parvovirus infection, and rabies.

Deadly canine parvo virus (CPV)
Parvovirus is a viral disease caused by canine parvovirus (CPV) in dogs. The disease generally affects young dogs of age between six weeks to six months of age. The virus occurs in two different forms –

• Intestinal – which is characterized by vomiting, foul smelly bloody diarrhea, anemia, pale mucus membrane weight loss, and lack of appetite

• Cardiac – a less common form, which affects the heart muscles of very young puppies.

The virus enters the body through the mouth as the puppy cleans itself or eats food off the ground or floor and the common entry point of infection being through fecal-oral route. There is a 3–7 day incubation period before the puppy seems obviously ill. The virus starts replicating in the pharyngeal lymph tissue and from there the infection spreads in the bod. In the blood the white blood cells are destroyed leading to reduced immunity.

The virus sets up infection in the intestine, normal intestine possesses finger-like projection referred to as villi. The viral agent destroys the villi of the intestine thereby affecting absorption of nutrients in the intestine causing diarrhea. With reduced immunity and heightened diarrhea, there occurs a loss of intestinal barrier which allows secondary bacterial organism to invade the living system. Bloody diarrhea and vomiting might lead to extreme fluid loss and dehydration in your pet.

The course of illness is also highly variable depending on the infectious dose of the virus. The clinical signs usually develop from 3 to 5 days following infection and typically persist for 5–7 days. The morbidity and mortality vary according to the age of the animals and the severity of the infection. Puppies can die suddenly of shock as early as after two days of illness.

The second form of CPV is cardiac syndrome, or myocarditis, which can affect puppies under age of 3 months. Acute heart failure with respiratory distress occurs in pups between 4 and 8 weeks of age. Sub-acute heart failure occurs in older pups, usually aged 8 weeks or more. Most pets die due to cardiogenic shock. However, if the pet survives it will suffer from chronic myocardial and circulatory complications.

Treatment & prevention of CPV
Puppies admitted with severe hypovolemia need reestablishment of their circulating volume in 1–2 hours. Balanced isotonic crystalloid solution (eg, Lactated Ringers) is the fluid of choice for initial restoration and rehydration. Proper antibiotic therapy is given to reduce the secondary bacterial invasion. However, the disease is fatal and to reduce the occurrence of disease proper and complete vaccination is necessary.

Danger of canine distemper (CD)
Canine distemper is a viral disease caused by moribili virus. It is also known as CD, old dog encephalitis, Carre’s disease, and hard pad disease. The disease is characterized by presence of biphasic fever accompanied with eye and nasal discharges, loss in appetite, diarrhea, circling movement, seizures, and thickening of the foot pad in animals. The virus enters the body through inhalation of droplets from infected animals. After gaining entry the virus multiplies in the respiratory tract and establishes infection in tonsils and bronchial lymph node. Widespread circulation of the virus occurs through the bloodstream establishing infection in different organs. The virus has grave affects on the nervous system leading to encephalitis, seizures, and circling movement along with twitching of muscles, and convulsions

Treatment & prevention of CD
Treatment is generally symptomatic and supportive to correct the fluid imbalance, to control nervous signs, and to limit the secondary bacterial invasion. Broad spectrum antibiotics, balanced electrolyte solution, antipyretics, analgesics, and anticonvulsants are used to limit the disease. Unfortunately in cases with nervous symptoms the treatment of disease is quite unsuccessful. In certain cases with multisystem involvement the pet might overcome the ailments related to respiratory and gastrointestinal symptoms with prompt car. However, the nervous signs may persist lifelong.

As the disease could prove to be fatal, the only way to protect your pets is to complete the vaccination. If you have a puppy, make sure he gets his first vaccination at six to eight weeks of age. Be sure to keep him away from any possibly infectious dogs or environments until he is finished with his vaccinations at four or five months old. Also, routine cleaning and disinfecting the kennel will ensure that the virus is not present in your pet’s living environment. Pet parents should follow the vaccination schedule, and those whose pets have CD should ask their vets for lifestyle changes for a happy and prolonged life.

Perils of infectious canine hepatitis (ICH)
ICH is a viral disease of unvaccinated young canines caused by canine adenovirus (CAV). The disease is also called as blue eye disease because of the cloudiness in the eye. It is characterized by pale mucus membranes, jaundice/ icterus, vomiting, and in certain cases clouding in eye is also noticed. Ingestion of urine, feces, or saliva of infected dogs is the main cause of infection. The infection initially sets up in tonsil and peyer’s patches in the intestine. The virus then spreads to other organs through blood circulation. The target organ for the disease is liver and the infectious agent damages the liver and kidney to cause hemorrhages. In certain cases cloudiness of eye or corneal opacity is observed due to immune complex formation.

ICH occurs in dogs with a more prolonged course of disease. Puppies with CAV-1 encephalitis may show signs of circling, vocalization, head pressing, ataxia, and blindness. Ocular complications are observed in around 20 percent of affected dogs.

Treatment & prevention of ICH
Treatment of the disease is symptomatic and supportive and is aimed to correct the electrolyte imbalance and fluid loss and to minimize secondary bacterial infection. Broad spectrum antibiotic therapies are given. In certain cases of severely ill dogs, blood transfusion or plasma administration is suggested. For better control of the disease proper vaccination is suggested.

Rabies
Rabies is also known as mad dog in animals and hydrophobia in case of humans. It is caused by lyssa virus. Rabies is a highly fatal viral infections of the central nervous system (CNS), affecting all the warm-blooded animals. The transmission of disease occurs by the bite of an infected/carrier animal who inoculate the virus into the wounds.

An effective treatment for viral diseases is yet not found and only supportive symptomatic therapies are given to lessen the adverse impact on pets. The only way possible to reduce the occurrences of such fatal disease is to have proper vaccination in both domestic and stray animals. There are many vaccines available either monovalent (single) or polyvalent (combination) that can be used for effective vaccination there by reducing disease occurrence. Stray animals are more exposed to such viral agents and play role in communicating diseases to the domestic animals, therefore stray animals should also be vaccinated.

(Dr Diksha Kandpal is from GB Pant University of Agriculture and Technology, Pantnagar Uttrakhand)