Diseases and Parasites

Diseases & Parasites Health Protocols • The greatest impact on disease management is determined by the measures directly taken to prevent and treat disease. • Develop a standard (and preferably written) health protocol. • Define goals & outline specific means of ensuring the objectives are achieved. • SOP for: identifying, examining, separating and treating sick animals; administration of routine health procedures and schedules (vaccinations, deworming, castration, etc.); and general husbandry procedures. How vaccines work: • Passive Immunization How vaccines work: • Active Immunization How vaccines work: • Passive Immunization – Brief period of protection – Antibody absorption one time only • Active Immunization – Prolonged period of protection – Boosting of protective response by additional exposure Vaccination • All horses should be vaccinated for diseases that are prevalent in the area. • Not all diseases can be vaccinated against. • Vaccines are not 100% effective for disease prevention. • Vaccination protocols should be reviewed annually. Who, What, Where, When, Why….. • • • • • • Eastern Encephalitis Western Encephalitis Venezuelan Encephalitis West Nile Encephalitis Influenza Equine Herpes Virus – Respiratory – Abortion • • • • • • Rabies Streptococcus equi (strangles) Potomac Horse Fever (Neorickettsia risticii) Clostridium botulinum Equine Protazoal Myelitis (EPM) Equine Viral Arteritis • Tetanus – Tetanus toxoid – Tetanus antitoxin Currently there are equine vaccines available for: • Tetanus – formalin-inactivated, adjuvanted toxoid – Tetanus antitoxin for passive immunity (high risk) • Arboviruses – Eastern (EEE)-75% Mortality – Western (WEE)-30% Mortality – Venezuelan Viral Encephalomyelitis (VEE) – 40-90% Mortality – West Nile Virus (WNV) - killed or modified live EEE 2007 Cases West Nile Virus 2007 Cases Currently there are equine vaccines available for: • Influenza, many different strains : injection / intranasal • Equine Herpevirus – EHV-1 - abortion, respiratory, and neurological disease – EHV-4 - respiratory disease Currently there are equine vaccines available for: • Strangles : injection of killed bacterin / intranasal vaccine • Rabies : injection of killed virus Uncommon Vaccines Given • Potomac Horse Fever : killed rickettsia • Equine protozoal Myelitis (EPM): killed protozoan • Botulism : killed vaccine (toxoid) – licensed for prevention of Shaker Foal Syndrome (Kentucky & mid-Atlantic state) • Equine Viral Arteritis • Anthrax • Endotoxemia • Rotavirus EQUINE VIRAL ARTERITIS – Fever – Edema (or swelling especially in the legs, genitals and around the eyes), – Abortion – Nasal discharge, – Skin rash (localized or generalized) – Loss of appetite. • EVA IS A VIRUS, ONCE CONTRACTED, THERE IS NO direct treatment for it. Treatment is focused on alleviating symptoms to ease the horse’s recovery. Equine Viral Arteritis • • • Caused by equine arteritis virus (EAV). Not usually lethal to adult horses. Transmission – Aerosol – Venereal – Indirect (urine, AI, feces, vaginal secretions) • • • Once infected recover within a few weeks. They shed the virus and become immune, but will test seropositive the rest of their lives. Horses exposed to EVA, including mares bred to EVA-positive stallions, must be properly quarantined to prevent the spread of the virus. Horses and semen testing positive for EVA may not be allowed to be exported to other countries. Before vaccinating, discuss the risks with your veterinarian Vesicular Stomatitis • Caused by a virus • Transmitted by insect vectors • Primarily affects horses, cattle, and swine but other susceptible species include camelids, wildlife, sheep, goats, and humans Vesicular Stomatitis • Vesicles that rupture produce ulcers • Salivation, anorexia, and weight loss secondary to oral lesions • Lameness with coronary band lesions • Horses: upper surface of the tongue, surface of the lips and around nostrils, corners of the mouth and the gums. • Recovery in around 2 weeks. • Complication: loss of production and mastitis in dairy herds due to secondary infections, lameness in horses. Should You Vaccinate? • How serious is this disease? • How well does the vaccine work? • What is the frequency and seriousness of the side effects of the vaccine? • Does protecting the horse also protect other horses or the horse owner from contracting the disease? • Does vaccination result in persistence of the disease in the population? • Does the vaccine create a diagnostic enigma or cause export restrictions? • Does the vaccine create export or transport restrictions Vaccine EEE/WEE* West Nile Virus* Rabies* Tetanus* Pleasure or Show Pregnant Mare Pasture Horse Boarding Facility Weanling (> 6 mo) Frequency Annual X X X X X X X X X X X X X X X May/Sept Annual Annual X X X X +/Atlantic states High rate of X X X X +/- X X X X X +/- X +/+/+/+/- Herpes (Rhino) Influenza Strangles Q 6 months Q 6 months Annual April/June PHF EPM Botulism +/- Maternal Protect High rate of Risk Assessment • Boarding & training facilities have a high volume of horses with a rapid turnover rate. • Breeding farms have a high number of horses with a high turnover rate. • Farm & ranch settings have working horses that remain in the same facility until sold or deceased. • High performance horses have a high workload & are exposed to many other horses from different backgrounds General Farm Practices Breeding Farms • Foaling represents a significantly higher disease risk period for both the mare and the foal. • During late gestation the mare’s immune system is reduced. • The neonatal foal has limited immune capabilities for many months. General Farm Practices Breeding Farms • Provide a clean, hygienic foaling environment. • Disinfect the navel soon after birth. • Ensure every foal ingests an adequate amount of quality colostrum. • Test the foal for adequate blood IgG levels. • Limit contact between very young foals and older animals. General Farm Practices Weaning • One of the greatest periods of stress & disease. • Stall or small paddock results in increased stocking density, enhancing the transmissibility of disease. • Ideally, the mare is removed and the foal is left in familiar surroundings. – Limits the exposure of the foal to new pathogens. • Increased disease susceptibility. • Four main factors: decreased nutrient absorption, poor teeth, decreased immune response and age-related disease. – Decreased absorption of phosphorus, vitamins, and protein. General Farm Practices Geriatric Horses • Antibody response to vaccination is decreased and T cell function is lowered. • Prone to develop age-related disorders such as liver failure, kidney disease, tumors, and anemia. Suspected Case of Infectious Respiratory Disease Establish Biosecurity Perimeter Communicate the Plan Attempt Diagnosis Equine Herpes Virus-1 Influenza Strep. Equi. Equine Viral Arteritis Suspected Case of Infectious Neurologic Disease Establish Biosecurity Perimeter Communicate the Plan Attempt Diagnosis EHV-1 Rabies WEE/EEE/VEE Botulism WNV Suspected Case of Infectious Diarrheal Disease Establish Biosecurity Perimeter Communicate the Plan Attempt Diagnosis Salmonellosis Potomac Horse Fever Clostridiosis PARASITES • Strongyles (bloodworms) • Ascarids (roundworms) • Bots • Pinworms • Strongyloides (threadworms Signs of Parasitism • Dull, rough hair coat • Lethargy • Wt. Loss • Coughing &/or nasal discharge • Tail rubbing • Colic • Summer sores • • • • • Depression Anorexic Unthriftiness Diarrhea Resistance to bit MANAGEMENT FOR CONTROL OF INTERNAL PARASITES • • • • • Proper manure disposal Pastures Feed Water Drug control What to know about dewormers • • • • What parasites they kill What stages of parasites they kill Egg reappearance period Safety in young or pregnant animals Benzimidazoles (fenbendazole, oxibendazole, mebendazole) • Effective against strongyle adults (fenbendazole 2x/5 day will get migrating and encysted larvae), round worms, pin worms • Small strongyles may be resistance to these drugs • Suppress egg production 4 wks Tetrahydropyrimidine (pyrantel pamoate) • Effective against adult round worms, strongyles, and pinworms. • Can be given as daily low dose, but has been associated with small strongyle resistance • Suppress egg counts 4 wks Macrocyclic Lactones (ivermectin and Mocidectin) • Effective against round worms, strongyles, bots, and pinworms – fenbendazole at higher doses will kill a higher percentage of roundworms • Moxidectin will kill encysted small strongyle larvae