Zoonotic Disease in Dogs

There are a number of diseases which can be passed from animals to humans. One such disease is bacterial in nature, methicillin resistant staphylococcus aureus (MRSA) while the other is viral (rabies). Additionally, both of these diseases can be fatal to either or both hosts, MRSA being the more treatable with some degree of success. 

In the case of rabies, treatment options and the degree of success therein is dependent upon the stage to which the disease has progressed in at least one host, and if the appropriate treatment is begun early enough. The vital importance of immediate medical assistance is emphasized for anyone who has been bitten by an animal, whether that animal is visibly rabid or not. Emphasis is placed on the importance of getting the animal tested if it is available for testing and the willingness to submit to treatment in the event the animal is not available for testing. 

In the case of MRSA (methicillin resistant staphylococcus aureus) or MRSP (methicillin resistant staphylococcus pseudintermedius) in animals, is treatable in both animals and humans if it is identified and treated as early as possible. This zoonotic disease can also be fatal if not treated in an appropriate and timely manner, especially if the host suffers from a weakened immune system. Medical attention should be sought as soon as the earliest symptoms begin to appear so that the bacterial offender can be identified and treated quickly.

Zoonotic disease is defined as a disease that can be passed from animals to humans. This communication can occur in various ways, all of which involve infiltration of bacteria or viruses into various types of tissue in the body, whether transferred from animal to human or vice versa.

Rabies 

• Extreme behavior changes like restlessness or apprehension, both of which could be worsened by aggression
• Your pet could go from friendly to irritable, or from excitable to docile, or may snap or bite any type of stimulus attacking other animals, humans and even inanimate objects
• He may bite, lick or chew at the site where he was bitten
• Fever may be present at this stage
• Sensitivity to light, touch and even sound will present and increase as virus progresses
• He may eat unusual things
• His eating habits and patterns may change
• Your dog may hide in dark places
• Paralysis of throat and jaw muscles causing foaming at the mouth
• Disorientation
• Lack of coordination and/or staggering as a result of the paralysis of the hind legs
• Loss of appetite
• Weakness
• Seizures
• Sudden death

MRSA, MRSP, MRSS

The MRSA infection can take several forms and medical designations depending on the organism responsible for the infection. 

• Skin infections
• Abscesses or boils
• Wound infections
• Ulcerations of the skin
• Blisters filled with pus or mucus
• Scaling
• Hypopigmentation (loss of color)
• Hair loss

Additionally, some people, as well as some animals can be carriers of the bacteria (called colonizations) without necessarily becoming sick.

Types

Rabies

The various types of rabies are designated by the animal which is the host or the source of the infection:

• Canine - dogs and coyotes
• Skunk
• Raccoon
• Fox
• Feline
• Bat

Two other types are also referred to in an attempt to describe the degree of progression or the principal manifestations:

• Furious rabies describes animals with pronounced aggression
• Dumb or paralytic rabies describes animals with minimal behavior changes and whose principal manifestation is paresis or paralysis

MRSA, MRSP, MRSS

• MRSA - methicillin resistant staphylococcus aureus 
• MRSP - methicillin resistant staphylococcus pseudintermedius
• MRSS is also an acronym for a related disease known as methicillin resistant staphylococcus schleiferi

Rabies

• Rabies is caused by lyssaviruses in the rhabdovirus family
• These viruses are generally transmitted via the saliva from an animal bite
• This bite can come from any carnivore, such as dog, coyote, skunk, rabbit, fox raccoon, feline or bat. 
• After exposure it can be from 2 to 8 weeks before the symptoms appear
• Once the symptoms appear, they progress to death
• Records show that most rabies cases in dogs generally develop within a period of 21 to 80 days after the initial exposure
• The rabies virus travels through peripheral nerves to the spinal cord, then up to the brain

MRSA, MRSP, MRSS

These infections are all methicillin resistant staphylococcus aureus bacteria in origin. They are designated with similar names and all share these causes:

• They are bacterial in nature and the bacteria are normally found on skin and in nasal passages of both humans and some animals
• The bacteria are not common in all animals
• These infections can be transmitted by direct contact with infected individuals
• Contaminated environments
• Invasion of recent medical procedures (surgical sites and wounds)
• Exposure to staphylococcus aureus via skin to skin contact
• Both people and animals can carry MRSA on their skin or in their noses and not have any visible signs of sickness

The diagnosis of rabies can be difficult especially for those cases found in areas in which rabies is not very common. Unfortunately, the early stages can be confused with other illnesses being that some diseases share the aggressiveness and some of the other symptoms experienced in those early rabid stages. 

Laboratory testing will provide confirmation and this testing is vitally important. The lab will need to do tests on the animal’s brain to confirm the presence of the rabies virus. Unfortunately, the only way to do this is to euthanize the affected animal and send the remains for lab testing. 

For the MRSA and associated infections, identification of the offending organism is generally done by using a swab to collect fluid specimens from the infected area and sending the swab to a laboratory for pathological review. The veterinarian or primary care doctor will carefully do this as she examines the injury site. Once the responsible bacteria has been identified, an appropriate treatment plan will be developed which will include an antibiotic administration either orally or by injection to treat the infection.

The National Association of State Public Health Veterinarians (NASPHV) has recommended that any unvaccinated cat, dog or ferret that has been exposed to rabies be euthanized immediately. If the owner refuses or is otherwise unwilling to do so, the animal should be placed in strict isolation (this means no human or animal contact) for 6 months and vaccinated against rabies one month before release. In the case of vaccinated domestic animals who have been exposed to rabies, they recommend that the currently vaccinated animal be revaccinated immediately and then closely monitored for 45 days. Euthanization is the ultimate resolution for any of these animals in the event that the symptoms and signs progress unless the disease resultant death of the animal occurs.

Unlike rabies, if your pet has contracted MRSA, MRSP or MRSS infection, it is not necessary to euthanize or otherwise get rid of the animal. You should discuss the situation with your veterinarian and human health care provider for the options available. It is important to note here that, since colonization of the bacteria on the skin of animals and humans alike is a factor, the actual source of the infection may actually be a member of your household. The treatments for these infections varies. Skin infections are generally treated with topical cleaning agents and antibiotic ointments and more serious infections are treated with oral and injectable antibiotic medications.

Rabies has the highest case fatality rates of any infection disease. As a result, when a person is exposed to an animal who is suspected of having rabies, it is vital that the risk of possible transmission of rabies be carefully and thoroughly evaluated. Any domestic dog, cat or ferret who is otherwise healthy, whether vaccinated or not, and who exposes a person should be confined for 10 days. This exposure can be any biting or other type of deposit of saliva in a fresh wound or on a mucous membrane. 

• Vaccinate your animals against rabies and keep up with the boosters
• Monitor all outside activities for both pets and people
• Always keep your pet on a leash when outdoors and maintain strict control at all times
• Maintain a constant vigilance against uninvited wildlife coming into contact with your pet and your family members 

With MRSA, resolution of the infection at the local site is expected, based upon the overall health of the person or animal and the condition of their immune system. But once the infection is healed, the host who has been treated can become a carrier for the rest of their lives. This doesn’t necessarily mean that future infections are guaranteed but only that the risk is higher. Extra precautions for wound care may be recommended especially for those individuals, animal and human alike, whose overall general health puts them at risk for future infections. Keep in close contact with your veterinarian and human health care provider for continued care.