The use of antiviral medications in veterinary practice is extremely limited. Most infections that are caused by viral infections are better prevented by vaccination. However, the following antivirals may be encountered in veterinary practice.

Trifluridine -- a pyrimidine analogue, used primarily for the treatment of feline ocular herpes. Only about 50% of cases respond.

Idoxuridine -- also a pyrimidine analogue, used for the same infection, dosing every 2 hours generally limits the usefulness of this agent.

Acyclovir -- Oral acyclovir is used for the treatment of feline herpes that is unresponsive to topical therapy. The dose is 200 mg q.i.d. Acyclovir may also be used in the treatment of Pacheco’s disease (parrot herpes).

Interferon -- this cytokine possess antiviral, anti-proliferative, and immunomodulatory actions. It is primarily used in the treatment of non-neoplastic feline leukæmia viral (FeLV) infections. The dose is 30 IU (1 ml) orally once daily for 7 days. A seven day drug holiday then follows, with 7 day on/off therapy alternating thereafter. Interferon is available as a 3,000,000 IU/ml solution. The pharmacist should prepare serial dilutions to acheive the appropriate concentration for use in cats (the dilutions may be frozen and stored for years, by certain references, and used to make subsequent preparations). Interferon may also be used as an appetite stimulant in dogs (the dose is 1 IU/10 lbs every other week) although this use has not been approved.

Many vaccines against both bacterial (Clostridial, Staphylococcal, Streptococcal) and viral diseases are available. These are all used on an as needed basis (i.e. when an outbreak occurs, all animals in the area are vaccinated).

Recommended Small Animal Vaccinations:
Canine

Recommendation	Disease	Puppy	Adult	Booster
Required	Rabies	3 months and 1 year	2 doses, 1 year apart	every 3 years or by local ordinance
Highly recommended	Distemper (MLV)	2-4 months	2 doses, 1 month apart	annual
"	Adenovirus	"	"	"
"	Parainfluenza	"	"	"
"	Parvovirus (MLV)	"	1 dose	"
Recommended	Bordatella bronchiseptica	6-8 weeks and 10-12 weeks	2 doses, 2-4 weeks apart	"

 

Feline

Recommendation	Disease	Kitten	Adult	Booster
Required	Rabies	3 months and 1 year	2 doses, 1 year apart	every 3 years or by local ordinance
Highly recommended	Panleukopænia (MLV)	9 and 12 weeks	2 doses, 3 to 4 weeks apart	annual
"	Respiratory complex, herpes virus, calicivirus	"  (Also available as topical or nasal spray for shelters,	"  pounds, and catteries)	"
"	Feline Leukæmia Virus (FeLV)	9 and 12 weeks	2 doses, 3 to 4 weeks apart	"  (Indoor, adult cats, optional)
Recommended	Feline Infectious Peritonitis (FIP)	16 and 20 weeks	"	"

 
 

Selected Veterinary Viral Disease States -- For many of these diseases, the prognosis is poor and treatment is primarily supportive. Euthanasia is often the final treatment in these diseases.

Small Animal
Rabies -- Acute Viral Encephalomyelitis -- Mortality near 100%, Rabies presents in three distinct phases.
Prodromal Phase -- this phase may or may not be observed. The animal stops eating and drinking and will often seek solitude, similar to many other disease states.

Excitive Phase -- this phase may be absent or it may predominate. This is the "furious" form of rabies that is often characterised as "mad-dog". The animal becomes violently aggressive.

Paralytic Form -- The animal develops paralysis of throat and jaw muscles with increase salivation (drooling). Bites are uncommon during this phase of rabies.

Canine Distemper (Hardpad Disease) -- Paramyxovirus (related to human measles) -- characterised by a biphasic fever, leukopænia, GI and respiratory catarrh, pulmonary lesions, neurologic complications (muscle spasms, chorea, paralysis, and convulsions), and hyperkeratosis of the footpads.

Canine Parvovirus -- Presents as two forms, either myocarditis or enteritis. The myocarditis presents primarily in pups. The enteritis presents as anorexia, lethargy, dehydration, vomiting, and bloody diarrhœa. The animal will often either recovery quickly or die.

Feline Panleukopænia (Feline Distemper) -- Parvovirus. This disease has a high mortality rate (60-90% death within 5-7 days). It presents as pyrexia and anorexia progressing to diarrhœa, vomiting, and dehydration.

Feline Leukæmia (FeLV) -- While cats with FeLV may live for a long time with no apparent distress, they exhibit a marked predisposition to neoplasias (especially lymphosarcoma), peritonitis, anæmias, enteritis, and abortion.

Feline Infectious Peritonitis (FIP) -- Coronovirus. Animals exhibit fever, conjunctivitis, respiratory tract infection, and diarrhœa. FIP may present as either wet (ascites, pleural effusion) which is more common or dry (granulomatous lesions in the CNS and eye). Mortality is near 100%.

Large Animal Viral Diseases
Equine Encephalomyelitis -- Arboviruses (alphaviruses), transmitted by mosquitoes. There are three variants on this disease, Eastern (EEE), Western (WEE), and Venezualan (VEE). All three may present with fever, impaired vision, irregular gait, wandering, depressed reflexes, pendulous lower lip, and head pressing.

Foot and Mouth Disease (Hoof and Mouth) -- Rhinovirus (enterovirus). Animals exhibit lip-smacking, drooling, shaking and kicking, and the formation of vesicles on the nose, mouth, between toes, bottom of the foot, and on the udder/teats. Mortality is 100% and spread of the infection can be rapid.

Bluetongue (MLV) -- Insect transmitted orbivirus. Produces dyspnœa, hyperæmia, pyrexia, lameness, and a swollen, cyanotic tongue.

Rinderpest -- Morbillivirus. Livestock present with fever, anorexia, depression, diarrhœa, oculonasal discharge, and cheesy, necrotic lesions on the oral mucosa.

Mad Cow Disease (Bovine Spongiform Encephalopathy, BSE) -- The exact causative agent of this disease is not known. It was thought to be viral, but current theories and evidence support an unconventional or slow virus or prion as being the causative agent. BSE was first diagnosed in Great Britain in 1986. Since that time, over 150,000 cattle have died, with a peak 34,000 cases in 1989 and as many as 15,000 in 1996. It is very similar to scrapie in sheep and similar diseases in minks and pigs. It is also very similar to two human diseases, kuru which occurs only in the cannibal tribes of Papua New Guinea and Creutzfeldt-Jakob Disease.

BSE presents as apprehensive behaviour that progresses to aggression and frenzy with kicking during milking, ataxia, decreased milk yield, incoordination, hypermetria, falling, generalised paresis, tremors, fasciculations, and emaciation. The intense pruritus that is observed in scrapie does not occur with BSE. Necropsy findings are confined to the CNS where large vacuoles cause the brain to resemble a sponge. (This characteristic is common to BSE, scrapie, kuru, Creutzfeld-Jakob, and other similar diseases.) The first initial exposure is thought to have been through food that was infected with contaminated sheep by-products.

Creutzfeld-Jakob disease is a subacute spongiform encephalopathy of man. Contamination occurs via transplant, contaminated electrodes, or contaminated drugs that are derived from infected human or animal sources. It presents as dementia, self-neglect, apathy, irritability, sleep disturbances, myoclonus associated with sensory stimuli. It may have a 15 year incubation period. The myoclonus typically appears within 6 months of the onset of symptoms and death occurs within 3-12 months.

There have been only 10 diagnosed cases of BSE spreading to man, through contaminated beef, with 8 deaths. No new cases have been reported since 1989, due to stricter controls and a massive extermination programme. However, the Ministry of Agriculture and the Ministry of Health of Great Britain indicate that due to the long latency, additional cases could appear.