Juvenile foxes (Vulpes spp.) are vulnerable to a spectrum of health issues that can adversely affect their survival and development. These include infectious diseases, nutritional deficiencies and traumatic injuries. Comprehensive knowledge of the clinical presentation and management of these conditions is essential for veterinarians. In contrast to many other wildlife species, foxes are not covered by the Wildlife Acts of 1976 to 2012, meaning that ownership of foxes does not require a licence.
The aim of this article is to aid veterinary practitioners in efficiently handling cases involving juvenile foxes, with a principal emphasis on ensuring the welfare of these highly intelligent animals.
Common health issues in juvenile foxes
Infectious diseases
Canine adenovirus
Foxes have the potential to serve as carriers of viruses that affect domestic dogs. Infectious canine hepatitis (CAV-1) is sporadically observed in the UK’s indigenous fox population. Clinical manifestations of this disease range from anorexia, rhinitis, haemorrhagic diarrhoea, jaundice, hyperexcitability, seizures, paralysis, coma and death.
The prognosis for a fox displaying clinical signs of infectious canine hepatitis is guarded. Even if recovery ensues, viral shedding in urine may persist for up to six months post-infection. Due to the considerable risk of transmission, euthanasia is often considered advisable (Thompson et al., 2010).
Canine distemper virus
Canine distemper virus (CDV) is a highly contagious viral disease that affects a range of carnivores, including juvenile foxes. Respiratory symptoms include dry/moist coughing and nasal discharge, while gastrointestinal signs consist of vomiting and diarrhoea. Neurological manifestations range from tremors to seizures and paralysis. Ocular signs, such as conjunctivitis, are also common.
Diagnosis is confirmed through polymerase chain reaction (PCR) analyses of blood, cerebrospinal fluid and tissue samples, as well as histopathological examination showing characteristic inclusion bodies (Deem et al., 2001; Rossiter, 2001).
Parvovirus
Parvovirus represents a notable viral pathogen that induces acute haemorrhagic gastroenteritis in juvenile foxes. Manifestations of this disease encompass severe haemorrhagic diarrhoea, vomiting and marked dehydration. The resilience of parvovirus in the environment poses challenges to control measures. Diagnosis entails assessing clinical symptoms alongside PCR and enzyme-linked immunosorbent assay (ELISA) analyses of faecal samples (Decaro et al., 2007).
Sarcoptic mange
Sarcoptic mange, caused by the mite Sarcoptes scabiei, results in intense pruritus, alopecia and skin thickening due to hyperkeratosis (Figure 1). Juvenile foxes are particularly susceptible because of their immature immune systems.
Diagnosis is confirmed through skin scrapings and microscopic identification of mites. This condition is often associated with secondary bacterial infections due to the compromised skin barrier (Bornstein et al., 2001).
Endoparasites
Toxocara canis and Uncinaria stenocephala are the prevalent parasites observed in foxes in the UK.
Young cubs are at the highest risk of exhibiting clinical symptoms and should receive anthelmintic treatment (Smith et al., 2003). Treatment typically consists of deworming medications, such as pyrantel or fenbendazole.
Nutritional deficiencies
Calcium deficiency is commonly observed in juvenile foxes raised in captivity and provided with an unbalanced diet. Clinical manifestations comprise skeletal anomalies, such as osteopenia and pathological fractures, as well as dental irregularities and hypocalcaemic tetany.
Another deficiency is hypovitaminosis A, which is characterised by nervous disturbances (including xerophthalmia, head tilting and abortions). The growth of deficient animals while good at first, declined in the late stages. The minimum vitamin A requirement necessary to prevent the occurrence of the nervous symptoms in growing pups lies between 15 and 25 I. U. per kilogram of body weight per day (Sedgwick , 1942).
Traumatic injuries
Many of these animals are diagnosed with fractures and other injuries, including head trauma, which can result in traumatic brain injury (TBI) and lead to neurological and behavioral disorders. Additionally, infections secondary to injuries, such as abscesses and parasitic infestations, are also frequently observed (Kuo et al., 2018).
Bite wounds commonly result in abscess formation, potentially leading to cellulitis and septicaemia. Beta-haemolytic Streptococci are frequently isolated from these wounds, necessitating appropriate antimicrobial therapy. An amoxicillin/clavulanate combination can be used as a first-line treatment option at 8.75mg/kg SID (SC or IM) or 12.5 to 25mg/kg BID (orally) for a minimum of seven days. Infected wounds may progress to secondary toxic liver damage or haemolysis, resulting in severe jaundice and indicating the need for immediate euthanasia (Barrat et al., 1985).
Entanglement or snare injuries often result in pressure necrosis and reperfusion injury. In these situations, it is crucial to thoroughly examine the fox’s oral cavity, as attempts to disentangle themselves may result in oral injuries (Barrat et al., 1985).
Diagnostic approaches to common health issues in juvenile foxes
Clinical examination
A comprehensive clinical examination (Figure 2) is fundamental to successfully triaging any wildlife case. This includes evaluating vital signs and body condition and looking for specific symptoms, such as respiratory distress, neurological deficits or dermatological lesions. Detailed history-taking and observing behaviour are also crucial components of the diagnostic process (Sykes and Greene, 2012).
Knowing the precise location where a fox is discovered is critical for rehabilitators, as it allows them to release the animal back into its native area. This is especially vital for cubs as they are frequently brought in by the public under the mistaken belief that they are injured or orphaned. These cubs should be immediately returned to their original site and monitored the next morning to confirm that the mother has returned to care for them.
A fox’s resting heart rate is typically around 125bpm, though this may be elevated due to the stress of the examination. Their normal rectal temperature ranges from 39°C to 40°C.
Diagnostics
When diagnosing issues in juvenile foxes, laboratory diagnostics are indispensable for identifying specific pathogens and assessing overall health. Complete blood counts (CBC), biochemical profiles and serological tests (eg PCR and ELISA) are essential for diagnosing infectious diseases. Blood chemistry panels can also reveal underlying metabolic or organ dysfunctions (Hartmann et al., 2015).
Blood sampling is ideally performed via the jugular or cephalic veins (Figure 3) and can be conducted on a conscious animal if properly restrained. The indications for routine bloodwork are similar to those for domestic dogs.
Behavioural considerations when treating and diagnosing juvenile foxes
Juvenile foxes often face emotional challenges, such as fear and anxiety, in clinical settings. Therefore, frequent hiding, excessive vocalisation and aggression are often seen. Establishing a safe, calm atmosphere, minimising stress caused by handling and offering opportunities for behavioural enrichment can help address these concerns. In more severe instances, midazolam might be used to alleviate anxiety and enable smoother treatment processes.
Clinical management strategies for common health issues in juvenile foxes
Although no drugs are specifically licensed for use in foxes, the general guideline is to treat foxes with the same drugs and dosages as domestic dogs. Preferably, oral medications administered with food should be used, as they minimise handling and reduce stress. (Comprehensive drug doses are beyond the scope of this article but are available in veterinary formularies and wildlife-specific textbooks.)
Antiviral and antibacterial therapy
For viral infections such as CDV, supportive care is crucial. This includes fluid therapy (Figure 4), nutritional support and managing secondary bacterial infections with appropriate antibiotics. Antiviral treatments may be used in some cases, although they are not universally effective. For parvovirus, intensive supportive care, including intravenous fluids and broad-spectrum antibiotics, is essential to manage dehydration and prevent secondary infections (Sykes and Greene, 2012).
Antiparasitic treatment
Sarcoptic mange is treated with antiparasitic medications, such as selamectin (15mg for juvenile foxes weighing up to 2.5kg) administered topically and applied at monthly intervals until a negative skin scrape is obtained (Couper, 2016). Antiparasitic medications can also be used to treat fleas, ear mites and roundworms. Supportive treatments include anti-inflammatory medications and medicated baths to alleviate pruritus and promote skin healing (Bornstein et al., 2001).
Nutritional management
Providing a balanced diet rich in essential vitamins and minerals is critical for juvenile foxes. Formulated diets and dietary supplements (eg Welpi) can help achieve nutritional balance. The protein requirement for optimal nitrogen retention in a fox pup aged 50 to 161 days exceeds 40.7 percent in the dry diet. However, a protein level of 28 percent in the diet has been shown to support rapid growth, similar to higher protein intakes. For fox pups aged 162 to 259 days, the recommended protein allowance in their diet on a dry matter basis should range from 19 to 25 percent (Figure 5) (Harris et al., 1951).
Feeding foxes is straightforward, as cubs readily consume canine milk replacer (Figure 6). In captivity, it’s important to mimic the natural process of cubs transitioning from milk to solid foods, which typically begins at around four weeks of age. Encouraging independent feeding as early as possible is essential. Therefore, practitioners should introduce proprietary puppy food and chopped day-old chick starting at four weeks of age. Weaning the cubs can occur at six weeks (Couper, 2016).
Husbandry
Additional heat should be offered to any animals experiencing shock, as well as to young cubs under four weeks of age. Cubs younger than two weeks old are incapable of regulating their body temperature.
Be sure to provide a hiding area for the fox and ensure all enclosures are suitably covered. It is crucial to minimise unnecessary contact with cubs to prevent imprinting. Ideally, they should be housed with other cubs of similar age whenever possible.
Conclusion
Addressing the myriad health challenges faced by juvenile foxes is crucial for their survival and overall welfare. These challenges, ranging from infectious diseases to traumatic injuries and nutritional deficiencies, necessitate prompt and effective management through clinical examination, diagnostic testing and suitable medical or surgical interventions.
Continuous research efforts and advancements in veterinary practices are paramount to elevate the standard of care and ensure the conservation of these vulnerable animals.
